Technical Report published by

Technology Deployment Program

Western Federal Lands Highway Division

Federal Highway Administration

610 East 5th St.

Vancouver, WA 98661

For more information 

or additional copies contact:

Amit Armstrong, Ph. D., P.E. 

Phone: 360.619.7668

Fax: 360.619.7846

Amit.Armstrong@fhwa.dot.gov

RR cover v3.indd 1 
ROADSIDE REVEGETATION

AN INTEGRATED APPROACH TO ESTABLISHING NATIVE PLANTS

Report Number: FHWA-WFL/TD-07-005

Technology Deployment Program

Western Federal Lands Highway Division

Federal Highway Administration

610 East 5th St.

Vancouver, WA 98661

Technology Deployment Report
intentionally left blank
Technical Report Documentation Page

1. Report No.

 FHWA-WFL/TD-07-005

2. Government Accession No. 3. Recipient’s Catalog No.

4. Title and Subtitle

Roadside Revegetation: An Integrated Approach To 

Establishing Native Plants

5. Report Date

 November 2007

6. Performing Organization Code

7. Author(s)

David E. Steinfeld, Scott A. Riley, Kim M. Wilkinson, 

Thomas D. Landis, Lee E. Riley

8. Performing Organization Report No.

9. Performing Organization Name and Address

 Umatilla National Forest

 U.S. Forest Service

 2517 S.W. Hailey Ave.

 Pendleton, OR 97801

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

12. Sponsoring Agency Name and Address

 Federal Highway Administration

 Western Federal Lands Highway Division

 610 East 5th St.

 Vancouver, WA 98661

13. Type of Report and Period Covered

Final Report 2007

14. Sponsoring Agency Code

 HFL-17

15. Supplementary Notes

 Technical Editing: Amit Armstrong, Ph.D., P.E.

Copy Editing: Sarah Wasill, Kathleen Gabriel

 Layout Design: Diane Pearse

 COTR: Amit Armstrong, Ph.D., P.E.

This project was funded under the FHWA Federal Lands Highway Technology 

Deployment Initiatives and Partnership Program (TDIPP) and Coordinated 

Technology Implementation Program (CTIP).

16. Abstract

Native plants are a foundation of ecological function, aff ecting soil 

conservation, wildlife habitat, plant communities, invasive species, and water 

quality. Establishing locally-adapted, self-sustaining plant communities can also 

support transportation goals for safety and effi ciency. 

Past obstacles to establishing native plant communities on roadsides have 

been technical, informational, and organizational. Eff ective strategies and practical 

techniques for revegetating the disturbed conditions with limited resources must 

be made available to practitioners. Multiple disciplines, ranging from engineering 

to soil science, ecology, botany, and wildlife science, must be able to work 

cooperatively, not in isolation. 

This report off ers an integrated approach to facilitate the successful 

establishment of native plants along roadsides and other areas of disturbance 

associated with road modifi cations. It guides readers through a comprehensive 

process of: 1) initiating, 2) planning, 3) implementing, and 4) monitoring a roadside 

revegetation project with native plants.

17. Key Words

REVEGETATION, NATIVE PLANTS, ROAD 

DESIGN, ROAD CONSTRUCTION

18. Distribution Statement

 No restriction. This document 

is available to the public from the 

sponsoring agency at the website 

http://www.wfl .fhwa.dot.gov/td/.

19. Security Classif. (of this report)

Unclassifi ed

20. Security Classif. (of this page)

Unclassifi ed

21. No. of Pages

424

22. Price

 $0.00

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
SI* (MODERN METRIC) CONVERSION FACTORS

APPROXIMATE CONVERSIONS TO SI UNITS

Symbol When You Know Multiply By To Find Symbol 

LENGTH

in inches 25.4 millimeters mm 

ft feet 0.305 meters m 

yd yards 0.914 meters m 

mi miles 1.61 kilometers km

AREA

in2 square inches 645.2 square millimeters mm2 

ft2 square feet 0.093 square meters m2

yd2 square yard 0.836 square meters m2 

ac acres 0.405 hectares ha 

mi2 square miles 2.59 square kilometers km2

VOLUME

fl oz fl uid ounces 29.57 milliliters mL 

gal gallons 3.785 liters L 

ft3 cubic feet 0.028 cubic meters m3

yd3 cubic yards 0.765 cubic meters m3

NOTE: volumes greater than 1000 L shall be shown in m3

MASS

oz ounces 28.35 grams g 

lb pounds 0.454 kilograms kg 

T short tons (2000 lb) 0.907 megagrams (or “metric ton”) Mg (or “t”)

TEMPERATURE (exact degrees)

°F Fahrenheit 5 (F-32)/9 Celsius °C

or (F-32)/1.8

ILLUMINATION

fc foot-candles 10.76 lux lx 

fl foot-Lamberts 3.426 candela/m2 cd/m2

FORCE and PRESSURE or STRESS 

lbf poundforce 4.45 newtons N 

lbf/in2 poundforce per square inch 6.89 kilopascals kPa

APPROXIMATE CONVERSIONS FROM SI UNITS

Symbol When You Know Multiply By To Find Symbol

LENGTH

mm millimeters 0.039 inches in 

m meters 3.28 feet ft 

m meters 1.09 yards yd 

km kilometers 0.621 miles mi 

AREA

mm2 square millimeters 0.0016 square inches in2

m2 square meters 10.764 square feet ft2

m2 square meters 1.195 square yards yd2

ha hectares 2.47 acres ac 

km2

 square kilometers 0.386 square miles mi2 

VOLUME

mL milliliters 0.034 fl uid ounces fl oz 

L liters 0.264 gallons gal 

m3 cubic meters 35.314 cubic feet ft3

m3 cubic meters 1.307 cubic yards yd3

MASS

g grams 0.035 ounces oz 

kg kilograms 2.202 pounds lb 

Mg (or “t”) megagrams (or “metric ton”) 1.103 short tons (2000 lb) T 

TEMPERATURE (exact degrees)

°C Celsius 1.8C+32 Fahrenheit °F

ILLUMINATION

lx lux 0.0929 foot-candles fc 

cd/m2 candela/m2 0.2919 foot-Lamberts fl 

FORCE and PRESSURE or STRESS

N newtons 0.225 poundforce lbf 

kPa kilopascals 0.145 poundforce per square inch lbf/in2

* SI is the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of 

ASTM E380. (Revised March 2003)
ROADSIDE REVEGETATION:

AN INTEGRATED APPROACH TO ESTABLISHING NATIVE PLANTS

TABLE OF CONTENTS

 List of Acronyms

1 Introduction 1

 1.1 Introduction 1

 1.2 The ecological eff ects of roads 1

 1.3 Objectives of this report 5

 1.4 Scope 5

 1.5 Approach 6

 1.6 How this report is organized 8

 1.7 Summary 12

2 Initiation Part One: Cooperators and Processes for Road Projects 13

 2.1 Introduction 13

 2.2 Preliminary tasks of initiation 13

 2.3 The process of road development 16

 2.4 Next steps 19

3 Initiation Part Two: Road Plans and Terminology 20

 3.1 Introduction 20

 3.2 Reading plans 20

 3.3 Interpreting engineering views for revegetation planning 23

 3.4 Understanding technical concepts and terminology 24

 3.5 Next steps 24

4 Planning Phase One: Orient 29

 4.1 Introduction 29

 4.2 Step one – Defi ne revegetation objectives 30

 4.3 Step two – Defi ne and map revegetation units 31

 4.4 Step three – Locate and describe reference sites 34

 4.5 Step four – Defi ne desired future conditions (DFCs) 40

 4.6 Next steps 42

5 Planning Phase Two: Assess Site 43

 5.1 Introduction 43

 5.2 Water input 45

 5.3 Available water storage and accessibility 50

 5.4 Water loss 64

 5.5 Nutrient cycling 70

 5.6 Surface stability 88

 5.7 Slope stability 101

 5.8 Weeds 109

i
 5.9 Pests 115

 5.10 Human interface 119

 5.11 Inventory site resources 122

 5.12 Phase two summary and next steps 124

6 Planning Phase Three: Vegetation Analysis 125

 6.1 Introduction 125

 6.2 Vegetation assessments 125

 6.3 Develop species lists for the project 126

 6.4 Identify target plant requirements 130

 6.5 Next steps 145

7 Planning Phase Four: Integrate and Strategize 146

 7.1 Introduction 146

 7.2 Finalize revegetation units and DFCs 146

 7.3 Integrate and develop revegetation strategies 147

 7.4 Select a revegetation strategy 147

 7.5 Assemble the revegetation plan 148

 7.6 Next steps 148

8 Revegetation Plan Example 155

9 Implementation 171

 9.1 Introduction 171

 9.2 Review plans with construction engineer 171

 9.3 Review treatment details and timelines 172

 9.4 Develop contracts 174

 9.5 Install treatments 175

 9.6 Keep good records 180

 9.7 Carry out quality assurance 180

 9.8 Implement early maintenance and monitoring 182

 9.9 Conclusion 182

10 Implementation Guides 183

 10.1 Soil and site treatments 183

 10.1.1 Fertilizers 184

 10.1.2 Tillage 195

 10.1.3 Mulches 201

 10.1.4 Topsoil 215

 10.1.5 Organic matter amendments 220

 10.1.6 Lime amendments 228

 10.1.7 Benefi cial soil microorganisms 231

 10.1.8 Topographic enhancements 244

 10.2 Obtaining plant materials 248

ii 10.2.1 Collecting wild seeds 248
 10.2.2 Collecting wild cuttings 256

 10.2.3 Collecting wild plants 265

 10.2.4 Nursery seed production 271

 10.2.5 Nursery cutting production 281

 10.2.6 Nursery plant production 286

 10.3 Installing plant materials 301

 10.3.1 Seeding 301

 10.3.2 Hydroseeding 311

 10.3.3 Installing cuttings 326

 10.3.4 Installing plants 333

 10.4 Post installation care of plant materials 345

 10.4.1 Introduction 345

 10.4.2 Animal protection 345

 10.4.3 Shade cards 347

 10.4.4 Tree shelters 348

 10.4.5 Irrigation 351

11 Monitoring and Management 358

 11.1 Introduction 358

 11.2 Revisit project objectives and DFCs 359

 11.3 Develop monitoring strategy and protocol(s) 359

 11.4 Record data and observations 362

 11.5 Evaluate data and apply any corrective measures 362

 11.6 Organize, fi le and report project results 365

 11.7 Share lessons learned 365

 11.8 Roadside maintenance and management 365

 11.9 Conclusion 365

12 Monitoring Protocols 366

 12.1 Introduction 366

 12.2 Soil cover protocol 367

 12.3 Species cover protocol 371

 12.4 Species presence protocol 372

 12.5 Plant density protocol 373

 12.6 Plant attributes protocol 374

 12.7 Sampling area design 375

 12.8 Sample size determination 380

 12.9 Statistical analysis using confi dence intervals 384

 12.10 Summary 394

13 Summary 395

 Bibliography 396

iii
LIST OF ACRONYMS:

AASHTO – American Association of State Highway and Transportation Offi cials 

AMF – Arbuscular mycorrhizal fungi, formerly called endomycorrhizae

AOSA – Association of Offi cial Seed Analysts 

AOSTA – Association of Seed Technologists Association

AWHC – Available Water-Holding Capacity 

BFM – Bonded Fiber Matrix

BLM – Bureau of Land Management

CCE – Calcium Carbonate Equivalent

CEC – Cation Exchange Capacity 

CRF – Control-Release Fertilizers 

COTR – Contracting Offi cer’s Technical Representative 

DEQ – Department of Environmental Quality

DFC – Desired Future Condition

DGRC – Dorena Genetic Resource Center 

DOT – Department of Transportation

EA – Environmental Analysis

EMC – Ectomycorrhizal Fungi

EPA – U.S. Environmental Protection Agency 

ECRM – Erosion Control Revegetative Mats 

ET – Evapotranspiration Rate

FHWA – Federal Highway Administration

FS – U.S. Forest Service

GIS – Geographic Information System 

LCL – Lower Confi dence Limit 

HWY – Highway

IBDU – Isobutylidene Diurea

IRVM – Integrated Roadside Vegetation Management

MTDC – Missoula Technology Development Center 

NAPT – North American Profi ciency Testing 

NEPA – National Environmental Policy Act 

NPDES – National Pollutant Discharge Elimination System 

NRCS – Natural Resources Conservation Services 

OM – Organic Matter

OHV – Off -Highway Vehicle

PAM – Polyacrylamides 

PIR – Project Identifi cation Report

PLS – Pure Live Seed 

PMS – Plant Moisture Stress 

PVC – Polyvinyl Chloride

RECP – Rolled Erosion Controlled Products

RGP – Root Growth Potential 

ROW – Right-of-Way

RQD – Rock Quality Design Index 

SME – Saturated Media Extract 

SMP – Shoemaker-McLean-Pratt buff er

SRI – Soil Resource Inventory 

STA – Seal of Testing Assurance 

TAWHC – Total Available Water-Holding Capacity 

TEUI – Terrestrial Ecological Unit Inventory 

TMECC – Test Methods of the Examination of Compost and Composting

TRM – Turf Reinforcement Mats 

TZ – Tetrazolium Test

UCL – Upper Confi dence Limit 

USDA – U.S. Department of Agriculture

USFS – U.S. Forest Service

UTM – Universal Transverse Mercator

WFLHD – Western Federal Lands Highways Division iv
intentionally left blank

v
intentionally left blank

vi
Figure 1.1 – Beginning 

revegetation with native 

species on scenic highway to 

Mt. Bachelor, OR.

Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring

& Management 

Summary

1

1 INTRODUCTION

1.1 INTRODUCTION

Integrating societal goals for safe, effi cient transportation with goals for ecological health is a 

crucial issue that is receiving increased attention (Forman and others 2003; NRC 2005). Today, 

most road projects involve modifi cations to existing roads rather than new construction (NRC 

2005). As roads are modifi ed or updated section by section, a tremendous opportunity presents 

itself to remedy the oversights of the past, mitigating environmental impacts and improving 

conditions for healthy ecosystems.

Native plants are a foundation of ecological function, aff ecting soil conservation, wildlife habitat, 

plant communities, invasive species, and water quality. Establishing locally-adapted, selfsustaining plant communities can also support transportation goals for safety and effi ciency.

Protecting existing native vegetation during construction and establishing native plants on 

roadsides following disturbance is key to integrating road systems into natural systems. 

Past obstacles to establishing native plant communities on roadsides have been technical, 

informational, and organizational. Eff ective strategies and practical techniques for revegetating 

the disturbed conditions with limited resources must be made available to practitioners. Multiple 

disciplines, ranging from engineering to soil science, ecology, botany, and wildlife science, 

must be able to work cooperatively, not in isolation. Finally, improved interagency cooperation 

and planning processes that consider ecological eff ects at every step are necessary.

This report off ers an integrated approach to facilitate the successful establishment of native 

plants along roadsides and other areas of disturbance associated with road modifi cations. 

It guides readers through a comprehensive process of: 1) initiating, 2) planning, 3) implementing, 

and 4) monitoring a roadside revegetation project with native plants.

1.2 THE ECOLOGICAL EFFECTS OF ROADS

The ecological eff ects of roads are widespread. The road system of the United States is over 

4 million miles long, paved roadways covering roughly 0.5% of the total land area of the country 

(NRC 2005). The total road corridor (paved road plus roadside or right-of-way) covers over 1% of 

the nation’s surface, an area equal to the size of South Carolina (Forman and Alexander 1998). 

If unpaved roads are also included, the percentages dramatically increase. The ecological eff ects 

of roads extend into a zone far beyond the edge of the pavement, with impacts including habitat 

fragmentation, wildlife mortality, noise and chemical pollution, disruption of hydrologic cycles 

and water quality, increased erosion, and the potential creation of transportation corridors for 

noxious and invasive weeds that can invade adjacent lands. With these considerations, the 

estimate is that 15% to 20% of the United States is ecologically impacted by roads (Forman 

and Alexander 1988). The enormous challenge of understanding and mitigating the ecological 

eff ects of roads deserves attention and dedication on local, regional, and national scales.
Figure 1.2 – Most existing roads 

were constructed prior to 1970, 

before ecological health became a 

widespread concern.

Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring 

& Management

Summary

2

1.2.1 Past Oversights

Much of the existing road network was designed and constructed prior to the 1970s, before 

ecological health became a widespread concern among American citizens and before 

ecological science had evolved to address large-scale issues (Forman and others 2003). 

Safety and effi ciency were the primary goals of transportation programs in the past, and the 

ecological impacts were largely overlooked in road planning, construction, and maintenance 

eff orts. The impacts of roads on natural systems (habitat fragmentation, interruption of 

natural fl ows of water, and disturbances to animals, plants, soils, and other resources) were 

not well understood or considered. Lack of awareness about these factors led to a largely 

antagonistic perception of the relationships between natural systems and road systems. 

For example, without eff ective revegetation of the road disturbance with desirable plants, 

undesirable vegetation encroaches on the roadway. Undesirable vegetation can disrupt safety 

and visibility, leading to expensive and potentially hazardous maintenance measures. Confl icts 

with neighboring land uses could result if corridors for invasive weeds are established or if 

vegetation control measures are viewed as a health or safety concern by the community. These 

are all issues that arise when integration of ecology and road design is not considered during 

road construction or modifi cation. Eventually, poorly integrated natural processes can threaten 

the function and structural integrity of the road itself, leading to premature deterioration of the 

road’s infrastructure (Berger 2005).

1.2.2 Present Awareness

For over twenty years, the ecological eff ects of roads have been increasingly recognized by the 

Federal Highway Administration and by state and county transportation agencies (NRC 2005). 

Today, road eff ects on ecology are major concerns among private citizens, land management 

agencies, and the transportation community. Attempting to integrate ecological concerns into 

all phases of road design and construction processes is an emphasis. For example, legislation 

in some areas now requires road modifi cation and construction projects to restore aquatic 

connectivity; fi sh passages have been built to reconnect natural water fl ows under roads. Other 

projects have dealt with roads that were deemed particularly dangerous to endangered species. 

These roads are being made more permeable to wildlife, greatly reducing losses by improving 

habitat connectivity, ensuring better visibility for drivers and animals, and creating safer 

underpasses or overpasses for wildlife (Forman and others 2003). Eff orts to limit inappropriate 

road expansion and to obliterate unnecessary roads remain important. Where modifi cation 

and increased capacity are needed, ecological health, safety, and effi cient transport should 

not be seen as mutually exclusive goals. Understanding roadside environments, how they 

interface with adjoining lands, and how to minimize environmental impacts has become a 

key focus of the Federal Highway Administration (Fekaris 2006). Given political will and proper 

levels of attention, integration of environmental concerns with transportation can result in 

signifi cant gains.
Figure 1.3 – Most road projects today 

do not involve building new roads, 

but rather modifying or obliterating 

existing roads. This photo shows recently 

planted trees on an obliterated section of 

highway in Oregon.

Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring

& Management 

Summary

3

1.2.3 Trends in Road Construction

Roads are widespread, fairly permanent fi xtures 

on the landscape and in the culture of the United 

States. Given current trends, road networks 

are expected to persist and expand over time. 

Current modifi cations predominantly involve 

updating infrastructure to increase capacity and 

to improve safety, including widening roads, 

replacing bridges, and reducing or altering 

curves and grades to make the road safer for 

motorists (NRC 2005). The opportunity to 

integrate ecological goals with transportation 

was largely overlooked when the road networks 

were originally constructed. However, as the 

nation’s roads are being updated and modifi ed, 

the opportunity cannot be ignored. While 

attempts to integrate ecological factors are 

positive, much of the potential for improved 

integration is still largely unrealized. This has 

been due, in part, to a shortage of practical 

information and the absence of an integrated 

approach to the challenge. The question is, 

what can be done to balance societal desires for 

safe, effi cient transport with requirements for a 

healthy environment? In other words, what can 

be done to help road systems function better 

with natural systems?

1.2.4 Challenges and Opportunities

The fact that the nation’s road networks are in varying states of updates, repairs, and maintenance 

presents an opportunity to improve road systems so that they integrate better with natural 

systems. Planners and practitioners strive to understand detrimental eff ects associated with 

roads and how to mitigate them by minimizing the ecological footprint of roads and maximizing 

potential ecological benefi ts. Many groundbreaking resources have emerged to support these 

eff orts. Road Ecology: Science and Solutions (Forman and others 2003) places the challenges into 

comprehensive frameworks, illuminating goals and principles for an ecological approach to 

transportation issues. Multiple intervention points are identifi ed to help road systems function 

better with natural systems, integrating transportation goals for safety and effi ciency with 

approaches to protect water, soil, vegetation, wildlife, and aquatic life. The Federal Highway 

Administration published a landmark book called Roadside Use of Native Plants (Harper-Lore and 

Wilson 2000) that brought the issue of native plant communities on roadsides to the forefront, 

highlighting the importance of native plants and their ranges of use. The National Research 

Council of the National Academies of Science built on the frameworks identifi ed in Forman and 

others (2003) in their publication, Assessing and Managing the Ecological Impacts of Paved Roads

(2005). Processes and procedures within the Federal Highway Administration, state departments 

of transportation, and other agencies are being improved for better integration.

In addition to these advances and other publications directly related to roads, many advances 

in the fi eld of restoration ecology have distilled essential principles applicable to severely 

degraded sites (e.g., Munshower 1994; SER 2004; Clewell and others 2005; Claassen 2006). 

Also vegetation specialists within many federal agencies have come to consensus about what 

truly defi nes a “native” plant and have developed seed collection, transfer, and propagation 

guidelines to ensure that locally adapted materials are used for optimum results (WithrowRobinson and Johnson 2006). In both the public and private sectors seed and plant producers 

and installers have been developing innovative methods to meet unique site conditions.

While the publications above assess the best available conceptual and theoretical information, 

each also recognizes extensive needs for further work, particularly in developing practical 

approaches to integrating ecological needs with transportation goals. Central to ecosystem 

function is native vegetation (SER 2004). However, much of the pertinent information related to 
Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring 

& Management

Summary

4

protecting and establishing native plants on roadsides has been scarce, scattered, unexamined, 

or not translated into practice. This report is intended to bridge some of the informational, 

technical, and organizational gaps to facilitate successful roadside revegetation with native 

plants. An integrated approach is off ered to support both planners and fi eld-based practitioners 

in successfully revegetating roadsides and obliterated roads with native plant communities.

1.2.5 Why Revegetate Roadsides With Native Plants?

Long-term economic and ecological advantages can be gained by establishing desirable 

native plant communities on roadsides (Berger 2005). Desirable vegetation can support safety 

goals by reducing headlight glare, reinforcing the road alignment, serving as crash barriers, 

protecting view planes and visibility, controlling snow drifts, and reducing wind speeds 

(Forman and others 2003). Vegetation can improve the experience of the road user by creating 

natural beauty and diversity along the roadside. A self-sustaining native plant community 

on a roadside stabilizes slopes, protecting water and soil quality. Also, the establishment of 

healthy native plant communities is often the best long-term defense against invasive and 

noxious weeds. Maintenance costs for managing problematic vegetation are reduced, as is the 

pollution and controversy that sometimes results from roadside herbicide use (Berger 2005). 

Establishing healthy roadside vegetation can also help sequester carbon dioxide, one of the 

factors responsible for global climate change (Palumbo and others 2004).

Using desirable vegetation supports every aspect of the goals identifi ed as Best Management 

Practices by the transportation community for road design. These include goals to:

 · Produce a safe, cost eff ective, environmentally friendly, and practical road design that is 

supported by and meets the needs of the users; 

 · Protect water quality and reduce sediment loading into water bodies; 

· Avoid conflicts with land use; 

 · Protect sensitive areas and reduce ecosystem impacts; 

 · Maintain natural channels, natural stream fl ow, and passage for aquatic organisms; 

 · Minimize ground and drainage channel disturbance; 

 · Control surface water on the road and stabilize the roadbed driving surface;

 · Control erosion and protect exposed soil areas; 

 · Implement needed slope stabilization measures and reduce mass wasting; 

 · Avoid problematic areas; and 

 · Stormproof and extend the useful life of the road (Keller and Sherar 2003 p.3).

Clearly, the goals of safe and efficient transportation and the goals of establishing and protecting 

native vegetation overlap; when properly integrated, native vegetation supports road objectives. 

At the same time, considering vegetation as part of road planning processes aids in minimizing 

and mitigating the ecological footprint of roads during and after construction. Native plants can 

provide wildlife habitat and improved connectivity for the length of the road (Forman and others 

2003). Understanding vegetation and forage preferences, and careful design that accounts 

for visibility and safety, can guide animals to safe passageways for travel while minimizing 

dangerous interactions with vehicles. The presence of birds and small animals can be enhanced 

when appropriate plant species are established. Processes that work for roadside revegetation 

are also applicable to the process of obliterating roads where roads are no longer needed.

Despite the potential benefi ts, many past attempts at roadside revegetation have not 

succeeded. Although revegetation was considered important, some eff orts emphasized 

seeding of exotic plants; these species were perceived as cheap, readily available, and easy to 

establish on disturbed sites. This practice has not been eff ective or self-sustaining; either the 

exotic grasses spread to become problematic weeds, or failed to persist because they were not 

locally appropriate species. Once established, exotics may preclude reintroduction of desirable 

natives. In other cases, little consideration was given to establishing roadside vegetation 

during or after construction; if vegetation was considered, it was often as an afterthought. 

A short-term approach to revegetating roadside disturbances often predominated past eff orts, 

while eff orts toward long-term development of native plant communities did not receive 

adequate consideration. The ineff ectiveness of revegetation eff orts in the past has resulted 
Figure 1.5 – Past shortcomings can often 

be attributed to a lack of an integrated 

approach and proper coordination. 

This photo shows an area recently 

revegetated with native plants that has been 

sprayed with herbicide.

Figure 1.4 – Steep slopes are often diffi cult 

to revegetate and many past attempts at 

roadside revegetation did not succeed. 

Inexpensive and readily-available exotic 

plants either failed to establish or became 

weeds. Integration of revegetation 

techniques into road planning and 

implementation increases the chances 

of success.

Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring

& Management 

Summary

5

in such problems as erosion and sediment loading, aff ecting soil and water quality. Visually, 

unvegetated road disturbances diminish the experience of the road user and economically 

translate into high costs associated with ongoing maintenance.

Past shortcomings may be attributed to past approaches. Past approaches were often piecemeal, 

lacking the cooperation and coordination of disciplines necessary to fully integrate native 

vegetation into the road planning and construction processes. Revegetation specialists typically 

worked in isolation from engineers, and sometimes even the biological specialists (soil scientists, 

botanists, wildlife biologists) failed to coordinate their knowledge and eff orts. Success will 

require both practical and technical information and a systematic, comprehensive approach.

1.3 OBJECTIVES OF THIS REPORT

This report brings theoretical and practical information to bear on the challenge of revegetating 

roadsides with native plants. Written by and for fi eld-based practitioners and planners, it 

synthesizes a comprehensive, holistic approach that can be utilized to eff ectively revegetate 

roads. Given the unique ecological factors at play on each project, the report is not prescriptive, 

but rather provides principles and a step-by-step process for practitioners to use in the fi eld to 

generate and implement their own locally-appropriate, context-sensitive revegetation plan. 

Examples and proven strategies are off ered to serve these goals. Topics covered include how to:

 · Improve interagency cooperation in order to think ecologically about road modifi cations 

and make revegetation an integral part of road design;

 · Coordinate information and eff orts to bring multiple disciplines like soil science, 

botany, ecology, wildlife science, and engineering together for a holistic approach 

to revegetation;

 · Integrate goals for native vegetation establishment with transportation goals for safety, 

function, and effi ciency;

 · Mitigate harsh, drastically disturbed conditions of road disturbance areas to enable 

native plants to establish through natural colonization and/or active replanting; and

 · Apply a step-by-step planning, implementation, and monitoring process, including 

mid-course corrections, to overcome potential pitfalls, resulting in cost-eff ective, 

successful establishment of native plants.

1.4 SCOPE

The complexity of ecologically-sensitive road design, implementation, and maintenance will 

require increasing cooperation from multiple sectors of society and multiple fi elds of practice 

and expertise. This report should be of interest not only to fi eld-level practitioners and planners 
Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring 

& Management

Summary

6

in both public and private sectors, but also to transportation and planning professionals, land 

managers, policy-makers, owners and operators of roads on county, state, and federal scales, 

and concerned citizens. Any agency or organization involved in altering, developing, operating, 

maintaining, or decommissioning roads will fi nd this publication useful. The report is especially 

intended to serve fi eld-based practitioners and planners of diverse backgrounds whose goal is 

to establish locally appropriate, low-maintenance native plant communities on roadsides.

Because integration of multiple sources of expertise is necessary for eff ective long-term 

revegetation, this report does not assume that the reader has a particular specialized 

background. Rather, the “revegetation specialist” addressed in the text may have a background 

in botany, ecology, soil science, engineering, biology, or other related areas of study. It is 

generally recommended that one practitioner be in charge of all the aspects of the revegetation 

project. This “revegetation specialist” will probably involve one or more other specialists during 

the planning process, depending on the project’s complexity. The report states where specifi c 

expertise is required (genetics, soil diagnosis, and so on). In all cases, the input and cooperation 

of the individuals and agencies involved with the road project is assumed. Key milestones for 

communication and integration between engineers and non-engineers are highlighted.

The approach in this report is applicable to any type of road-related project that involves 

disturbances to soil and vegetation. Revegetation of roadsides adjacent to dirt, gravel, and 

paved roads would involve similar processes, although diff erences in scale and intensity 

of eff orts would be required. This report applies to new construction or reconstruction and 

modifi cations of existing roadways. The principles and practices will also be applicable in 

revegetating other drastically disturbed sites with similar limiting factors to roadsides, such as 

gas, oil, or powerline rights-of-way, mine reclamation projects, and so on.

This report focuses on opportunities for intervention during road construction or modifi cation. 

Long-term maintenance and management of established roadsides is discussed briefl y, with 

references to related management practices and guidelines such as Integrated Roadside 

Vegetation Management (IRVM) (Berger 2005). Roads must be made more permeable to natural 

fl ows of water, animals, and plants if the road disturbance is to heal and not expand. Eff orts to 

improve habitat connectivity and road permeability, as well as storm water drainage and created 

wetlands, can be supported by the revegetation practices described in this report. However, 

specifi c mitigations for these important topics are beyond the scope of this publication. Also 

beyond the scope are the myriad other potential ecological and social issues that aff ect, and 

are aff ected by, the engineering and transportation planning processes. Issues of social justice 

and community planning are not addressed. Larger policy-making and planning procedures 

are also beyond the scope of this report.

1.5 APPROACH

The establishment of native plant communities in order to re-initiate natural processes of 

succession is a cornerstone of most ecological restoration work (Dorner 2002). Eff ective 

revegetation on highly disturbed roadsides aims to initiate or accelerate processes of 

natural succession following disturbances. Three aspects are generally considered: 1) health 

(the functional processes of the ecosystem); 2) integrity (species composition and community 

structure); and 3) sustainability (resistance to disturbance and resilience) (Clewell and others 

2005). While restoring plant communities to a pre-disturbance state is not a goal (or even a 

feasible idea) on highly disturbed roadsides, each of the above three ecosystem aspects can 

be improved with appropriate roadside revegetation practices. Establishing reference sites, or 

natural models for the desired recovery process, is key to identifying and overcoming limiting 

factors and accelerating succession by establishing native plants.

Native species play an important role in ecosystem development. If native species can colonize 

and become established on a disturbance, the processes of succession, including soil genesis and 

nutrient cycling, are initiated (Brown and Amacher 1999). In most cases, native plants are established 

on roadsides through seeding or planting, although sometimes passive revegetation (natural 

colonization) is possible where native seed banks are nearby and limiting factors are mitigated.

1.5.1 What is the “Roadside”?

In this report, the term “roadside” refers to any area of disturbance associated with road 

maintenance, modifi cation, or construction, including waste areas and source pits associated 
Figure 1.6 – The establishment of native 

plant communities is the cornerstone of 

ecological restoration.

Figure 1.7 – “Roadside” refers to disturbed 

areas resulting from road construction, 

modifi cation, or improper maintenance.

Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring

& Management 

Summary

7

with construction. The roadside includes the sides of the road corridor beyond the paved road 

(shoulders and verges), including impacted or maintained roadside areas within the right-ofway (ROW). The roadside area to be considered is sometimes narrow, but sometimes extends 

several hundred feet or more beyond the edge of the road surface, depending on the project. 

In some situations, revegetation eff orts may encompass areas beyond the ROW that are 

aff ected by or aff ect the road. The area where the revegetation specialists will be focusing their 

eff orts is usually dependent on two factors: ownership of the ROW and surrounding lands, and 

areas of disturbance (construction footprint). Most roadsides represent drastically disturbed 

environments, where soil may be severely compacted and consist of a mixture of subsoil 

and parent material. Benefi cial microorganisms, nutrients, and organic matter necessary to 

sustain plant growth may be absent or severely depleted. Often, slopes can be very steep and 

inaccessible, exposed to the erosive eff ects of wind and water. These environments represent a 

revegetation challenge of high intensity and magnitude.

1.5.2 What are Native Plants?

“Native plants,” as defi ned in this report, are locally-adapted, genetically appropriate native plant 

materials (Withrow-Robinson and Johnson 2006). These plants are best suited evolutionarily to 

the local conditions, and generally require less maintenance and persist longer than non-local 

species. When properly established, they form plant communities with the potential to be selfsustaining and self-perpetuating over time, requiring little or no input from humans to persist. 

Recent Policies Mandating Native Plants for Revegetation

Many land management agencies have policies mandating the use of native plants as the 

fi rst choice in revegetation eff orts. For example, the USDA Forest Service has the following 

policies in place applicable to road projects on Forest Service lands:

1) National Native Plant Materials Policy: “Native plant materials are the fi rst choice 

 in revegetation...” (USFS 2005)

2) BAER Manual (FSM 2523): “...when practical, use genetically local sources of native 

species...” (USFS 2003)

3) National Fire Plan Strategy: “...promote the establishment of local sources of native 

seed and other plant material...” (USFS/USDI 2001)

4) R6 Revegetation Policy: “...use local native plants to the extent practicable...” 

(USFS 2004)

5) NW Forest Plan; Interior Columbia Basin Ecosystem Management Project: “...maintain 

and restore native species and ecosystems...” (USFS/USDI 1994; USFS 2006)

6) Federal Register Notices: “...promote the use of native plant materials in revegetation 

for restoration and rehabilitation... native plant materials are the fi rst choice in 

revegetation for restoration and rehabilitation eff orts.” (FRN 2006)
Figure 1.8 – Roadsides are often 

drastically disturbed and infertile 

environments with no topsoil, severe 

compaction, and a lack of benefi cial 

microorganisms. They include 

obliterated roads and borrow sites as 

shown in this photograph.

Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring 

& Management

Summary

8

Challenges to establishing native plants on roadsides are signifi cant, partially due to 

diffi culties in obtaining appropriate materials. However, the technological capacity of native 

plant propagation and outplanting eff orts in both private and public sectors has increased 

signifi cantly in the past decade. Innovative stocktypes and application methods have made 

roadside revegetation more eff ective. Recent policy mandates from many federal agencies that 

manage roads now require the use of native plant materials as the fi rst choice in revegetation 

eff orts, thereby making roadside revegetation an important and expanding frontier for native 

plant suppliers. 

1.5.3 Goal-Oriented, Context-Sensitive, and Integrated

The overall approach in every aspect of this report is: 1) goal-oriented, 2) context-sensitive, 

and 3) integrated (Clark and others 2001). The goals of establishing and protecting native plant 

communities are considered along with transportation goals, including safety, effi ciency, and 

cost-eff ectiveness for the life of the road. This is not an idealistic approach; while recognizing 

that resources are limited and conditions are degraded, the approach is technically and 

economically feasible and still enables roads to integrate with ecological processes.

Sensitivity and appropriateness to the local context is an essential part of successful 

revegetation. This report is intended to facilitate the process of developing locally appropriate, 

context-sensitive prescriptions on a project-by-project basis, integrating top-down and 

ground-up information to meet the specifi c challenges at hand. For this reason, the report does 

not provide cookbook-type “recipes” or specifi c prescriptions. For example, no one-size-fi ts-all 

seed mix exists for roadside revegetation. Any information source emphasizing generalized 

prescriptions should be treated with suspicion. The process and tools needed to arrive at 

context-sensitive solutions are not diffi cult to apply; by following the steps outlined in this 

report, practitioners will be able to generate the information they need. 

The approach integrates multiple disciplines and the eff orts of multiple agencies and 

participants from both private and public sectors in a comprehensive process for eff ective 

revegetation with native plants. The report was written with inputs from specialists in soil 

science, botany, ecology, plant pathology, environmental management, and engineering, and 

is based on experiences in revegetating a range of diverse projects in the Pacifi c Northwest. 

The principles and methods used are broadly applicable nationwide.

1.6 HOW THIS REPORT IS ORGANIZED

The process of roadside revegetation consists of four stages: 1) initiation, 2) planning, 

3) implementation, and 4) monitoring and management. In Initiation, the revegetation specialist 

must gain an understanding of the agencies and cooperators involved in order to develop key 

relationships and navigate through the decision-making process. Synchronizing timelines for 

revegetation with road planning and construction is essential to ensure that conservation and 

revegetation is an integral part of the process. The Initiation chapters also help the reader to 

eff ectively interpret engineered road plans and communicate using standard terminology. 

The Planning chapters guide the reader through the process of understanding project objectives, 

assessing the site, designing mitigating treatments, strategizing revegetation procedures, and 

creating a revegetation plan. The Implementation chapters provide information on how to 
Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring

& Management 

Summary

Figure 1.9 – The project cycle consists of four phases: initiation, planning, implementation, and 

monitoring/management.

The

Project

Cycle

Initiation

Adapt

and

Improve

Initiation

of

Future Projects

Monitoring/

Management

Implementation

Planning

9

make the project unfold in the fi eld, including coordinating contracts, budgets, and schedules. 

Implementation Guides provide practical “how-to” information for working with soil and site 

treatments, obtaining plant materials, installing plant materials, and caring for plants in the 

fi eld. Finally, the Monitoring chapters describe how to assess the overall eff ectiveness of the 

revegetation project to contribute to adaptive management and future knowledge, and to 

correct any shortcomings in order to achieve project objectives. A summary of the process is 

provided in Figure 1.9 and Table 1.1. 

1.6.1 Initiation Overview

Eff ective roadside revegetation requires not only technical skills, but an ability to cultivate 

relationships and navigate the decision processes so a project will run smoothly. Road 

construction, alteration, or decommissioning involves a variety of land management agencies, 

programs, and regulations. The process of initiating a project is discussed in two parts. Initiation 

Part One orients the reader to learn about agency procedures for the organizations involved 

with road projects. Timelines, budgetary issues, and interface opportunities are outlined to 

enable the revegetation specialist to integrate revegetation eff orts with the overall process 

of road planning and construction. Attending meetings and coordinating with key contacts 

within agencies are important tasks in the early stages of the project.

Initiation Part Two provides the revegetation specialist with information to understand 

the current project site conditions, as well as predict the future condition of the project site 

following road construction. The revegetation specialist will become familiar with reading and 

interpreting road plans and understanding terminology. This ability enables the specialist to 

communicate eff ectively about engineering plans, contribute fully to minimizing the adverse 

environmental impacts, and ensure that revegetation is an integral part of the eff orts.

1.6.2 Planning Overview

Planning forms the foundation of future work. The Planning section of the report guides 

the reader through a comprehensive, holistic process culminating in the production of a 

revegetation plan. The process of planning is organized into four phases.

Phase One involves defi ning four essential aspects of the project: 1) the project objectives; 

2) the management areas (revegetation units); 3) the models (reference sites ); and 4) the specifi c 

goals for each revegetation unit (desired future conditions, DFCs). Defi ning these steps requires 

a preliminary assessment of site characteristics, including vegetation, climate, and soil.
Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring 

& Management

Summary

10

Table 1.1 – Overview of Roadside Revegetation Report.

Section Chapter Goal Tasks

Initiation 

Part One

Chapter 2

Understand 

cooperators 

and 

decision 

processes

Set up recordkeeping

Identify cooperators: Who is involved?

Defi ne cooperator processes, timelines, and 

milestones

Defi ne objectives: What is the project trying to 

accomplish?

Initiation 

Part Two

Chapter 3 Understand 

road 

plans and 

terminology

Read and interpret road construction plans

Understand key concepts and terminology

Planning 

Phase One

Chapter 4

Orient to 

the project

Determine revegetation objectives

Defi ne revegetation units

Select reference sites

Defi ne the desired future conditions

Planning 

Phase Two

Chapter 5

Assess site

Identify limiting factors

Consider mitigating measures for limiting factors

Assess site resources

Planning 

Phase Three

Chapter 6

Analyze 

vegetation

Complete vegetation assessment

Create a comprehensive species list

Defi ne plant communities and successional processes

Determine which species and groups of species will 

be used on the project

Identify target plant requirements

Create menu of potential stocktypes and plant 

establishment methods

Planning 

Phase Four

Chapter 7

Integrate 

and 

strategize

Finalize revegetation units and DFCs

Integrate survey information and develop potential 

revegetation strategies

Compare and select revegetation strategies

Assemble revegetation plan

Chapter 8 Example 

plan

Example revegetation plan

Implementation Chapters 

9 and 10

Implement

Review plans with construction engineer

Review revegetation treatment details and timelines

Develop contracts

Install treatments

Keep good records

Carry out quality control

Implement early maintenance and monitoring

Monitoring &

Management

Chapters 

11 and 12

Monitor, 

evaluate, 

correct, 

improve

Revisit project objectives and DFCs

Develop monitoring strategy and protocols

Record data and observations

Evaluate data and apply any corrective measures

Organize and fi le project results

Share lessons learned
Roadside

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Introduction

Initiation

Planning

Implementation

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Summary

11

Phase Two defi nes site attributes and limiting factors. Factors critical for plant establishment, 

such as soil and climate, are assessed. Obstacles to revegetation, as well as available resources, 

are examined. A fi eld investigation of each revegetation unit describes the site in depth and 

reveals how site characteristics will either support or limit achieving the DFCs. Based on the 

determination of limiting factors, a menu of possible mitigating measures for assuring plant 

establishment (short-term) and plant community development (long-term) is developed.

Phase Three matches plant species, genetic sources, stocktypes, and planting methods to 

the environmental conditions of the site. The vegetation is surveyed and analyzed. From 

a comprehensive list of species and plant communities present on the reference sites, the 

revegetation specialist determines which species are best adapted to the site and best suited to 

revegetation needs. Options for sources, stocktypes, and application methods are considered 

in order to achieve the desired results.

Phase Four combines all elements into a comprehensive strategy for revegetation. The possible 

options for site mitigation and revegetation methods are compared and considered, and the 

most promising are selected. Choices will be based on site factors and plant needs, and on 

other considerations, such as costs and availability of materials and services. There are always 

several ways to meet the revegetation objectives, and diff erent options are considered in Phase 

Four. When preferred strategies have been selected, budgets and schedules are developed 

and recommendations are compiled and presented in the Revegetation Plan.

1.6.3 Implementation Overview

Implementation involves coordinating and cooperating with diff erent contractors and 

agency personnel before, during, and after construction of the road. Treatments for soils and 

site conditions, obtaining plant materials, and installing and caring for plants are part of the 

implementation process. These chapters will help the reader to review plans with engineers, 

fi nalize treatment details and timelines, and develop the contracts necessary to successfully 

carry out the treatments. Keeping good records and carrying out quality assurance and 

early maintenance activities are essential aspects of the implementation phase. In all cases, 

coordinating the revegetation work with road construction or modifi cation processes is a 

major challenge, and a key opportunity to improve conditions for native plants.

Implementation Guides are short sections illustrating how to implement and/or contract for 

a particular treatment or mitigation measure. Guides are provided for: 1) working with soil/site 

treatments, 2) obtaining plant materials, 3) installing plant materials, and 4) caring for plants.

1.6.4 Monitoring and Management Overview

Monitoring is necessary to determine if goals defi ned at the outset of the project have been 

met. Scope, methods, and parameters for monitoring are determined on a project-by-project 

basis. These must be developed so that suffi cient and meaningful information is obtained 

effi ciently and interpreted properly. Keeping written records throughout the process of 

roadside revegetation is essential to evaluate each project.

Monitoring continues several years after implementation, providing a chance to assess 

eff ectiveness and correct any shortcomings. In the Planning section, project objectives 

describe an overall vision for the project. The desired future conditions refi ned the objectives 

into specifi c, measurable goals for the project site. Monitoring is an opportunity to evaluate the 

eff ectiveness of the revegetation eff orts as they relate to objectives and goals. 

Monitoring is essential for adaptive management of the project. Adaptive management is a 

systematic approach to good management guided by a process of regularly assessing and 

learning from what works and does not work on a project. As a project develops, monitoring 

can be used to assess progress and plan any necessary corrections.

When statistical methods will be necessary, Monitoring Protocols describe statistical sampling 

design, data collection techniques, and analysis methods for quantifi able parameters to 

determine success of roadside revegetation projects.

Revegetating roadsides with native plant communities is a developing fi eld. Practitioners 

are encouraged to share lessons learned, including successes and failures, to improve the 

knowledge base for future work.
Figure 1.10 – Native roadside 

revegetation in Glacier National Park. 

Photo by Tara Luna.

Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring 

& Management

Summary

12

1.7 SUMMARY

Balancing ecological health with safe and effi cient transportation is an enormous challenge. 

To protect environmental health and sustain the native plant communities of roadsides, 

conservation and revegetation eff orts must be an integral part of road design and construction. 

The process of roadside revegetation requires communication, interdisciplinary practice, and 

interagency cooperation. This report guides the reader through a comprehensive process for 

initiating, planning, implementing, and monitoring a project in order to successfully establish 

and perpetuate native plant communities on roadsides. It is hoped that this report will advance 

the science and technology of this fi eld and lead practitioners to more successful projects.
Roadside

Revegetation

Introduction

Initiation

Part I

Planning

Implementation

Monitoring

& Management 

Summary

13

2 INITIATION PART ONE: COOPERATORS AND PROCESSES 

FOR ROAD PROJECTS

2.1 INTRODUCTION

Incorporating ecological thinking into all aspects of road design, construction, modifi cation 

and maintenance is a goal of the transportation community (NRC 2005; Forman and others 

2003). The Federal Highway Administration, state departments of transportation, and other 

federal, state, and county agencies that work with roads seek to meet this goal. One way this 

goal is being addressed is to integrate issues of native plant revegetation (including protection 

of existing vegetation) into the larger design and construction processes of road projects. 

Considering revegetation in isolation from, or as an appendix to, the larger road project is a 

trend of the past that often resulted in failure. Instead, revegetation planning is now an integral 

part of road planning.

To ensure successful integration of revegetation issues with the overall road project, as the 

revegetation specialist and a fi eld-based practitioner you need to defi ne the cooperators 

and agencies involved, know how their processes and timelines work, and get involved at 

the appropriate times and with the appropriate people. You should expect to be involved in 

planning and construction processes whenever soil and vegetation disturbances are planned. 

Agency schedules, milestones, and budgetary issues must be defi ned to eff ectively synchronize 

the revegetation eff orts with road development and construction.

Road projects may be administered from local, state, or federal levels, or sometimes from a 

combination of all three levels. In terms of timing, road projects can be complex and span many 

years, whereas other projects are streamlined and quick. It is beyond the scope of this manual 

to cover all the specifi c procedures and processes for every agency involved in road projects. 

This chapter, however, provides an overview to successfully navigate the various processes for 

your project. Your involvement and input is important from the inception of a project through 

completion. The earlier you can get involved, the more input you will have. The preliminary 

steps for initial involvement are:

 · Set up recordkeeping.

 · Identify cooperators: Who is involved?

· Define cooperator processes, timelines, and milestones.

· Define objectives: What is the project trying to accomplish?

This chapter provides an overview of each of these steps, followed by a discussion of typical 

road development processes which include key points of involvement.

2.2 PRELIMINARY TASKS OF INITIATION

Roadside revegetation is a complex process, involving many agencies and individuals. A single 

revegetation specialist should be appointed to coordinate the planning, implementing, and 

monitoring/adaptive management of the revegetation aspects of the road project. You may 

enlist specialists from other natural resource disciplines to help with the revegetation planning 

so that expertise in botany, soil science, engineering, hydrology, wildlife biology, geology, and 

ecology is available for the project as necessary. You should be the coordinator of the technical 

and organizational aspects of the revegetation project, as well as the contact between 

revegetation eff orts and the other aspects of road planning and construction.

2.2.1 Initiate Recordkeeping

When initiating a project, it is important to set up a good system for keeping records and 

documenting the progress. Starting a diary with regular entries of meetings and site visits is a 

good, basic start. As the project progresses, narratives, data, photos, contracts, specifi cations, 

and other information will need to be organized and stored. The diary can begin to serve as 

a case history for the project. The information will be invaluable when implementing and 

later assessing the project. For now, start a folder in the computer (to include all e-mails and 

electronic documents) and a folder in the fi ling system for hardcopies, plan drafts, notes, and 

a daily journal.
Roadside

Revegetation

Introduction

Initiation

Part I

Planning

Implementation

Monitoring 

& Management

Summary

14

2.2.2 Identify Cooperators and Agencies: Who is Involved?

The process for road development will vary depending on the location of the road, which roadrelated programs and agencies are involved, and the complexity of the project. Interagency 

cooperation will almost always be part of the process. You must identify the agencies 

and individuals involved in the road construction project and their respective roles and 

responsibilities. It is especially important to identify: 1) who is the land owning agency, 2) who 

maintains the road, 3) who will be carrying out the road construction project, and 4) who is 

funding the project. All agencies and individuals involved have the responsibility to abide by 

rules and regulations as they work with the road.

2.2.3 Defi ne Cooperator Processes, Timelines, and Milestones

Once you have identifi ed the cooperators, you need to understand their processes, timelines, 

and milestones so that you can be involved with the right people at the right time. The 

timing, responsibilities, and, most important, processes associated with each agency will vary. 

While this may seem complicated, many agencies have a procedural manual that describes 

how a project is carried out from conception to completion, defi ning the timelines, milestones, 

roles and responsibilities, terminology, and how funding works. Locate these documents and 

agency manuals and use them. Initial meetings are also an ideal time to clarify these processes, 

when you fi rst begin working with agency personnel.

Each agency has certain approvals and procedural activities, including some that involve 

fulfi lling environmental regulations. You need to defi ne these activities and determine how 

your work fi ts with them. The steps in the approval process are often important milestones 

for the agency, and must be understood so that you can be part of decisions while there is still 

room for your input. Defi ning appropriate roles is essential so that you can coordinate with the 

proper people, follow protocols, and avoid duplicating eff orts.

Many variables aff ect the overall timelines from inception to construction. Timelines vary 

depending on the complexity of the project, the amount of controversy involved, and the 

availability of funds. Some projects take less than two years, while some can take over ten 

years. In all cases, the earlier you can get involved in the process, the better opportunities you 

will have to develop your plan and acquire the materials and support you need. This chapter, 

Figure 2.1, the agency procedural manuals, and your contacts within agencies can help you 

develop your own schedule and contact list specifi c to your project. Reviewing Figure 2.1 with 

the assigned road project engineer and discussing milestones, timelines, procedures, budgets, 

and roles is an eff ective approach to getting yourself oriented to the complex process of 

road development.

2.2.4 Defi ne Objectives: What is the Project Trying to Accomplish?

Once you understand the agencies and processes for each phase of the project, you need 

to understand how your work relates to the overall objectives of the project. Objectives can 

be found in the programming documents that originally identifi ed the need for the project. 

These objectives often center around improving safety or updating the road infrastructure. 

Phase One of the planning process (See Chapter 4) describes how to identify the objectives of 

the road project and translate them into specifi c goals for revegetation.

Environmental protection and maximizing the ability of the roadside to regenerate native 

vegetation will be one goal. The revegetation specialist should be involved when disturbances 

to soil and vegetation are planned. You are the key link to understanding the potential 

disturbances that might be caused and how to best minimize or mitigate them. Your input can 

help planners because you will know what types of disturbances can be feasibly revegetated 

with native plants. If a disturbance to soil and vegetation will not allow for revegetation, 

alternatives to that type of disturbance will need to be considered. Your input is crucial for 

assessing potential strategies and alternatives. The project objectives also help you determine 

the types of native vegetation that are most appropriate for your work. Are you working in 

a wildlife corridor? Is it a scenic drive? Is it an ecologically sensitive area with more intensive 

recovery needed? Are the slopes very steep?
Roadside

Revegetation

Introduction

Initiation

Part I

Planning

Implementation

Monitoring

& Management 

Summary

Environmental

Clearances & Approvals

Preliminary Road

Construction Plans

Project

Programmed

Project

Inception

Intermediate Road

Construction Plan

Final Road 

Construction Plan

Contract Award

Owner Agency

Acceptance

Maintenance Construction Road Project Development Programming Planning and

Periodic Meetings

with Construction

Final Monitoring

Report

Special Contract

Requirements

Contracts for

Plant Materials

Regular Construction 

Meetings

Implementation 

Tasks Begin 

Preliminary

Revegetation Plan

Revegetation

Planning Begins

Final Revegetation

Plan

Initiation Monitoring / Management Planning

Implementation

-1

0

1

2

3

4

5

6

7

8

-2

Revegetation

Aspect

Timeline

(Years)

Road

Project

15

Figure 2.1 – Coordinating revegetation with the larger processes of road construction is 

essential. While the timelines and agencies involved will vary, this fi gure illustrates some of the 

key opportunities for communication and integration.

Recognize that safety, effi ciency, and protecting and enhancing environmental health are 

all important priorities in road projects. While safety concerns may at times limit what is 

appropriate in roadside revegetation (e.g., tall trees along a roadside may be a desirable 

choice environmentally, but not from a safety or visibility standpoint), these concerns should 

not be viewed as an impediment to successfully revegetating roadsides. Instead, you simply 

need to be aware of how your revegetation work can complement safety objectives. Gain an 

understanding of safety issues, particularly regarding visibility and the ability of drivers to 

recover if they drive off the road and into the roadside area. (See discussion of how to defi ne 

roadside revegetation zones in Chapter 4.)
Roadside

Revegetation

Introduction

Initiation

Part I

Planning

Implementation

Monitoring 

& Management

Summary

16

2.3 THE PROCESS OF ROAD DEVELOPMENT

While each road agency will divide up and defi ne tasks diff erently, in general the process of 

road development has four stages: 1) planning and programming, 2) project development, 3) 

construction, and 4) maintenance. There are many opportunities for integration at each of 

these phases. For revegetation work, the implementation phase often begins well before road 

construction begins (with the collection of plant materials for propagation). Revegetation eff orts 

continue after road construction is completed. Figure 2.1 compares the revegetation process 

with the overall road development process, showing process steps where interface is crucial.

During road project development, a number of meetings will take place involving 

representatives from the agencies and interests involved with the project. During the 

planning phase, meetings usually take place at the preliminary, intermediate, and fi nal stages 

of the road plan. Ideally, the revegetation specialist should attend all these meetings. This 

ensures that good communication takes place and that trust is built during the road planning 

process. Meetings also ensure that regulations and requirements are met and that proper 

channels are utilized to get the job done. During the construction phase, the construction 

engineer and other key players carrying out the project will probably meet on a weekly basis. 

Attending some of these meetings is valuable so you can both learn and contribute as the 

project progresses. Clarify with your key contacts (such as the construction engineer) the 

most appropriate times to attend meetings. Contractors, inspectors, and other stakeholders 

may also be at meetings or at the fi eld site at any given time; clarify with your key contact the 

channels for you to communicate with other individuals who are involved with the project.

2.3.1 Road Planning and Programming

The process of deciding when to modify or build a section of road is often lengthy. Transportation 

planners identify and prioritize functional, structural, and safety issues regarding roads. 

If an issue is becoming problematic, alternatives to address it will be considered (FHWA 2005). 

Once it has been determined that a road will be modifi ed or updated, a budget and schedule 

are created. At this point, the project has been “programmed” for a specifi c delivery year. 

This process usually identifi es the following: 

 · Project purpose and need;

 · Roles and responsibilities of partnering agencies;

 · List of project alternatives established;

 · Primary contacts for project;

 · Preliminary project delivery schedule with milestones;

 · Collection and analysis of traffic data (accident history, average daily traffi c [ADT] 

volumes, etc.);

 · Preliminary construction cost estimate; and

 · Environmental concerns for the project (cultural and natural resource) and estimation 

of the affected environment (WFLHD 2005 p. 8).

A revegetation specialist will probably not be involved in a project until after it is programmed, 

although at times one might be called in to assess the feasibility of various alternatives.

Roadside Vegetation and Driver Safety

Greater safety for the traveling public is the primary objective of many road projects. 

As the revegetation specialist, you do not want to propose vegetation strategies that might 

make the roadway less safe. Integrating revegetation goals with safety goals requires an 

awareness of visibility issues, wildlife interactions, and other factors. Many road developers 

are interested in the concept of a “forgiving” roadside: a roadside environment that allows 

a driver to recover safely if they drive off the road into the roadside. Typically there will be 

a zone adjacent to the road where low grassy surfaces, or shrubs instead of trees, will be 

desirable for safety reasons. The roadside distance you need to consider to make a roadside 

forgiving depends on the speed limit of the highway and the traffi c volume. If both of these 

are high, a forgiving roadside will be a safety priority.
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2.3.2 Road Project Development

The road project development process begins after the project is programmed and ends 

when construction begins. Depending on environmental concerns and right-of-way issues, the 

project development process may take between one and fi ve years.

The road project development phase usually has three sub-phases. These involve developing, 

analyzing, and considering approaches and alternatives to the project until a strategy and 

specifi cations of how to best proceed are shared in the fi nal plan. The process usually involves:

 · Preliminary (road construction plans 30% complete);

 · Intermediate (road construction plans 50%-70% complete); and

 · Final (road construction plans 70-100% complete, hand off to construction).

2.3.2.1 Preliminary Phase

The preliminary development phase involves collecting information and initiating contacts 

with parties who are interested in or aff ected by the road construction (local and adjacent 

landowners, resource agencies, regulatory agencies, and any other potentially aff ected 

parties). The preliminary phase is necessary to refi ne purpose and need, to develop a range 

of alternatives to address purpose and need, and to obtain the approvals and clearances 

to allow the project to proceed. This includes commitments for environmental mitigation. 

The preliminary phase takes the road construction plans to about 30% completion. 

Once approvals and clearances are obtained, funds can typically be committed to continue 

development of the project.

Usually the preliminary phase will include the development and identifi cation of:

 · Preliminary construction plans (usually drafts about 30% complete) of the proposed 

alternatives (plan/profile sheets, typical sections, major work items identifi ed and located);

 · Preliminary construction cost estimates for alternatives;

 · Resource surveys (wetlands, archeological sites, and biological assessments);

 · Preliminary construction schedule;

· Identification of impacts and mitigation;

 · Environmental approvals and selection of alternatives for implementation; and

 · List of contacts for the project.

For the revegetation specialist, the preliminary phase is a crucial one. This phase represents 

the best opportunity for input regarding issues associated with revegetation, including 

disturbances planned for existing soil and vegetation on the site. Signifi cant features of the 

preliminary revegetation plan should be incorporated during this road planning phase. By the 

time of environmental approvals, the vegetative concepts and the necessary commitments of 

resources and funds should be integrated with the plan, as revegetation will be an important 

aspect of environmental protection and mitigation. The appropriate level of detail for the 

revegetation plan during the preliminary phase depends on the project. For the revegetation 

specialist, environmental guidelines may be predetermined by legislation that specifi es goals 

for the project regarding issues of soil stabilization, percent native vegetative cover, and 

protection of water quality. The revegetation specialist must be aware of these guidelines, and 

design them into the fi nal revegetation plan. Approvals are key milestones for the revegetation 

specialist regarding availability of funds to carry out site assessments and revegetation planning 

work including preliminary mapping and seed collections.

2.3.2.2 Intermediate Phase

The next phase of road development moves towards 50-70% completion of the road 

construction plans. This phase involves refi ning plans, obtaining rights-of-way and permits, 

and creating detailed plans and profi le sheets. The intermediate set of plans will include major 

budget items and quantities, information pertaining to environmental concerns (such as 

erosion control plans), and major elements such as grading, drainage, and other issues defi ned. 

At the intermediate stage, the revegetation specialist should be far along in the development 

of the revegetation plan. Mitigating measures have been identifi ed for impacted areas and 

contracts for seed and seedling production have begun. The intermediate set of road plans 
Roadside

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18

will include specifi cations for how the road project will be carried out. These specifi cations and 

contract requirements are key tools for the revegetation specialist.

2.3.2.2.1 Special Contract Requirements: A Key Tool for Revegetation

In every phase of road development, there are two key components: 1) plans (drawings) and 

2) specifi cations (contract descriptions). The plan sheets are drawings, blueprint-like visual 

representations of the proposed work as described in Chapter 3. Specifi cations are standards, 

provisions, and requirements that each agency provides to contractors or employees to carry 

out the work. A “special contract requirement” is a type of specifi cation. In general, special or 

standard specifi cations are written descriptions of intent, preferred methodology, timing, and 

standards for accomplishing the work. Standard specifi cations are uniformly carried out for 

most projects. Special requirements address context-sensitive concerns for a particular project. 

Special contract requirements are modifi cations of existing specifi cations found within the 

agency manual, or newly written specifi cations that are designed to address special concerns 

not adequately addressed in the standard contract specifi cations. For example, a standard 

specifi cation may exist for chipping woody debris; however, the standard specifi cation does 

not address size requirements of the chipped material. On your project, you may require a 

uniform size of material that should be shredded and screened, rather than chipped, to create 

optimal mulch for the project. To meet this requirement, you can create a specifi cation about 

required size (such as three inches or less in diameter) and processing needs (such as shredded 

and screened rather than chipped). Careful research is often needed to adequately develop and 

describe a special contract requirement, but it is essential in order to achieve the desired results 

in the fi eld. In the future, generically applicable special contract requirements may become 

adopted as standard requirements if they come to be utilized on most projects.

Special contract requirements are an important tool for revegetation specialists to communicate 

special expectations with contractors and to set standards for performance. You can specify 

to contractors what the requirements are, and how requirements might be met, measured, 

and paid for. Special contract requirements will be part of the contract, not an afterthought. 

By the intermediate phase, attention should have been given to modifying or creating contract 

Example of an Environmental Regulation Requirement

“Final Stabilization” Regulation (adapted from EPA 2006)

“Final stabilization” means that all soil disturbing activities at the site have been completed 

and that a uniform perennial vegetative cover with a density of at least 70% of the native 

background vegetative cover for the area has been established on all unpaved areas and areas 

not covered by permanent structures, or equivalent permanent stabilization measures.

“Final Stabilization” (adapted from EPA 2006) means that:

1) All soil disturbing activities at the site have been completed and either of the two 

following criteria are met:

 a) a uniform (i.e., evenly distributed, without large bare areas) perennial vegetative cover 

with a density of 70% of the native background vegetative cover for the area has been 

established on all unpaved areas and areas not covered by permanent structures, or

 b) equivalent permanent stabilization measures (such as the use of riprap, gabions, or 

geotextiles) have been employed.

2) When background native vegetation will cover less than 100% of the ground (e.g., arid 

areas, beaches), the 70% coverage criteria is adjusted as follows: if the native vegetation 

covers 50% of the ground, 70% of 50% (0.70 X 0.50 = 0.35) would require 35% total 

cover for fi nal stabilization. On a beach with no natural vegetation, no stabilization 

is required.

3) In arid and semi-arid areas only, all soil disturbing activities at the site have been 

completed and both of the following criteria have been met:

 a) Temporary erosion control measures (e.g., degradable rolled erosion control product) 

are selected, designed, and installed along with an appropriate seed base to provide 

erosion control for at least three years without active maintenance, and 

 b) The temporary erosion control measures are selected, designed, and installed to 

achieve 70% vegetative coverage within three years.
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19

requirements to meet the revegetation needs of the project. When specifi cations are not 

available for what you are trying to achieve, you need to be able to describe the work in terms 

of where, when, what needs to happen. Special contract requirements are included in the fi nal 

contract for the road construction project.

2.3.2.3 Final Phase

The fi nal set of road plans will include the design elements of the Revegetation Plan, as well as all 

the details for road construction. Plan sheets and contract specifi cations will be fully developed. 

Final cost estimates will be provided along with a comprehensive schedule. The work of the 

revegetation specialist in developing the revegetation plan, as well as eff orts to reduce the 

construction footprint and protect native vegetation on the project site, will be an integral part 

of the road construction plan. At this point, fi nalizing the revegetation plan will be necessary. It is 

also time to coordinate with contractors and agencies in order to time availability of plants with 

outplanting windows.

2.3.3 Construction

Following project development, the construction phase begins. Road construction can 

take one to three years. Sometimes there is a formal milestone when the project is handed 

off to construction personnel. If so, the construction engineer becomes an essential contact 

for the revegetation specialist, who may attend some of the weekly meetings that will take 

place during road construction. The construction phase of a road is completed when there is 

a formal acceptance of the road by the road owning agency. For the revegetation specialist, 

implementation and monitoring phases of revegetation may begin before road construction 

(with ordering plant materials, etc.) and continue following completion of construction.

2.3.4 Maintenance

Following construction of the road, the work of the revegetation specialist will usually continue 

for an additional one to three years until the revegetation is fully implemented. Also, the 

activities centered on monitoring and adaptive management of the establishing vegetation 

will continue to take place. These types of activities may continue for up to fi ve years after the 

road construction is complete. The submission of a fi nal monitoring report is the milestone 

marking the end of the revegetation specialist’s eff orts on the project. Coordination with the 

road owning agency and the individuals who carry out road maintenance will be essential to 

ensure that native vegetation continues to thrive on the site. For example, the agency taking 

ownership, often the county, could have maintenance methods that may ultimately undo 

portions of the revegetation, such as blanket herbicide use as standard practice along roadsides. 

It is essential to check what maintenance methods are utilized and to coordinate eff orts to 

ensure that management is appropriate for the native vegetation. The transportation agencies 

will continue to monitor the road to ensure that the problem that led to the road modifi cation 

(infrastructure decay, safety issues, etc.) was adequately addressed by the project.

2.4 NEXT STEPS

Eff ective integration of revegetation requires an understanding of the key agencies, programs, 

and relationships involved, as well as how decision processes work to move a road project 

forward. Successful navigation of the decision processes requires not only technical skills, but 

an ability to cultivate relationships and get involved at the appropriate times and with the 

appropriate people. Road construction, alteration, or decommissioning involves a variety of land 

management agencies, programs, and regulations. Understanding the procedures, timelines, 

and organizational structure of the agencies involved in a road project is essential in order for 

the revegetation specialist to contribute eff ectively throughout the process of road planning 

and construction. Attending meetings and coordinating with key contacts within agencies 

are important tasks. The revegetation specialist is usually involved at the beginning when the 

project is programmed, and continuing through and following construction. It is important 

to note (as illustrated on the timeline) that the implementation phase of revegetation begins 

while the overall project development process is still underway. Waiting until construction 

begins is not feasible because locally-adapted native plant materials almost always must be 

propagated in advance. The next step is to acquire the engineering plans for the road and to 

begin designing for revegetation.
Introduction

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20

3 INITIATION PART TWO: ROAD PLANS AND TERMINOLOGY

3.1 INTRODUCTION

Road construction often results in the drastic alteration of the surrounding landscape. In order 

to defi ne what these alterations will be and how to best plan revegetation, you need to be able 

to interpret road construction plans and terminology. This will enable you to defi ne the current 

site conditions and to visualize the future condition of the site following road construction. 

This chapter explains how to read and interpret:

 · Plan views,

· Profi le views,

 · Cross-section views,

 · Typical views, and

 · Summary of quantities tables.

The chapter then explains how to use these engineering views for revegetation planning, 

including determining the vegetation zones that begin where the pavement ends. A glossary 

with illustrations is provided in order to understand technical concepts and terminology for 

eff ective communication with others involved in road design and construction.

3.2 READING PLANS

The plan consists of construction drawings and specifi cations for each section of road. The four 

most common views of plans for the revegetation specialist are plan views, cross-section 

views, profi le views, and typical views. Each of these is defi ned in Table 3.1. Examples and 

guides for interpreting each of these views are provided below. Each engineering plan you 

receive will include a legend defi ning both abbreviations and symbols used throughout; learn 

to read these. Another invaluable component of the engineering plan is the tabulation of plan 

quantities table.

Table 3.1 – Defi nitions of Views (Keller and Sherar 2003)

Plan View A drawing depicting a section of the road from a bird’s eye view.

Profi le View A drawing depicting the vertical plane along the longitudinal centerline 

of the road, expressed in elevation or gradient. 

Cross-section 

View

A drawing depicting a section of the road viewed vertically, as if cut across 

the width of the road.

Typical View A drawing depicting features of a particular design, installation, 

construction or methodology. 

3.2.1 Plan View

The plan view shows the existing and proposed road locations from a bird’s eye view. 

The proposed road is usually designated with solid lines (Figure 3.1 A). The solid centerline 

(of the road to be constructed) is divided into 100 meter sections (large ticks), with 20 meter 

subdivisions also designated (small ticks – not shown). Each 20 meter division is called a station, 

representing a discrete, surveyed, and identifi able point within the road corridor. Each station 

is identifi ed with a unique number that indicates its distance from the beginning of the project. 

For example, the station 19+000 indicates this point is 19,000 meters from the start of the 

project; 19+040 meters indicates this point is 19,040 meters from the start. This short-hand 

identifi er is also used to indicate the placement of road-related infrastructure, such as culverts, 

the beginning and end of guard-rail construction, or the placement of a sign. In the fi eld, 

stations are identifi able as vertically aligned numbers written on wooden stakes and driven 

into the ground, facing the roadway. Not only do the stations provide locations, they help to 

locate revegetation units. The plans also show the top of the cut slope (Figure 3.1 B, dotted 

Roadside

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20
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line), bottom of the fi ll slopes (Figure 3.1 C, dashed lines), and the location of the original road 

(Figure 3.1 D, shaded area). In this example, the original road will be obliterated.

3.2.2 Profi le View

The profi le view is a trace of a vertical plane intersecting a particular surface of the proposed 

road construction (Figure 3.2 E). It corresponds to the longitudinal centerline of the road bed 

in the plans. Profi le grade means either elevation or gradient of the trace, depending on the 

context. The trace of the existing road is shown as a dashed line (Figure 3.2 F) and a dotted line 

(Figure 3.2 G). A vertical scale provides useful information about the profi le of construction 

grades throughout the project. This view shows where the proposed road will be lower than 

the existing road (Figure 3.2 H) and areas where it will be higher (Figure 3.2 I). Where the 

planned road is lower, material will usually be removed and used in areas needing fi ll. Additional 

information is often displayed adjacent to and locatable by the station numbers, such as 

volumes of excavation and embankment work, guard-rail placement, or wall placements.

3.2.3 Cross-Section View

Cross-sections are views of the slopes perpendicular to the direction of the road. They display 

a vertical section of the ground or structure at right angles to the centerline or baseline of 

the roadway. Depending on the length and topographic complexity of the road, there can be 

hundreds of cross-sections. Each cross-section is referenced back to a station. For example, the 

cross-section shown in Figure 3.3A depicts the slope at Station 18+940. It shows the proposed 

road (Figure 3.3 J), and the natural ground line as a dotted line (Figure 3.3 K). This section will 

have material brought in and placed as fi ll (Figure 3.3 L). The cross-section in Figure 3.3B shows 

a through cut at 19+000. Material will be removed from the natural ground line (Figure 3.3 K) to 

the proposed ground line – solid line (Figure 3.3 M).

Cross-section and plan views are used together to view the proposed road three-dimensionally. 

From these views, a more detailed revegetation plan can be developed. Each cross-section 

can be reviewed and a set of revegetation criteria can be developed for similar cross-sections 

throughout the project.

21

18+80018+90019+00019+100

19+200

1708

1710

1706

1704

1702

1700

1698

1696

1694

1692

1690

1688

F

H

E G

I

Figure 3.2 – Example profi le view. 18+800

R/W

R/W

R/W

R/W

18+90019+00019+10019+200

A

B

C

D

N 3 ̊ 46' 49" E

99182 255434.166 1410786.002 1696.398

99183 255544.687 1410818.803 1701.670

99184 255862.861 1410840.869 1704.295

Name Northing Easting

CONTROL POINTS

Elevation

CP

CP

CP

CP

99182

99183

99184

Culvert Obliterate

Old Road

Line to be

Constructed

Figure 3.1 – Example plan view.

21
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Roadside

Revegetation

Cross-sections provide the revegetation specialist a means to determine slope steepness. Crosssections show the proposed slope gradients for cut and fi ll slopes. Slope notation is expressed 

as vertical over horizontal (vertical:horizontal). When slopes are fl atter than 1:1 (45° or 100%), the 

slope is expressed as the ratio of one unit vertical to the number of units horizontal. For slopes 

steeper than 1:1, the slope ratio is expressed as number of units vertical to one unit horizontal. 

To avoid confusion, it is wise to notate the ratio by indicating the vertical and horizontal, for 

example 1V:2H, and to think in terms of rise over run (See Section 5.6.6.1).

3.2.4 Typical Views

Typical views graphically illustrate the design or construction details of the structures or other 

components that will be encountered in the road project. They can cover such structures as 

retaining walls, road surfaces, guardrails, ditch lines, plant installation, etc. They may be shown 

in profi le, cross-section, or plan views. Like special contract requirements (See Chapter 2), 

typical views are useful in helping communicate a new or modifi ed approach to an existing 

methodology or construction technique. The two example typical views in Figure 3.4 are 

related to plant placement and installation.

3.2.5 Summary of Quantities Table

Tabulation of plan quantities list quantities, types of materials, and performance specifi cations. 

For example, when working on federal or state projects, standardized specifi cations for 

construction are invaluable. The FHWA handbook: Standard Specifi cations for Construction of 

Roads and Bridges on Federal Highway Projects, is cited as “FP-03,” indicating “Federal Project” 

Standard Specifi cations issued in 2003. The state departments of transportation have 

analogous manuals as well. Tabulation of plan quantities references not only the particular 

item specifi cation number in the FP manual, but also the station number(s) of the planned 

work. Information of interest for the revegetation specialist includes the number of hectares of 

clearing and grubbing, hectares of obliterated roads listed by station, and the number of cubic 

meters of wood mulch to be produced. The summary of quantities table provides a single table 

summarizing all tabulation of plan quantity tables located throughout the plan. It generally 

does not include station numbers. Learn how to locate and read these tables.

22

18+940

J

K

CL

CL 1696

1694

1692

19+000

Des. Grd. = 1695.266

Subgrade = 1694.941

Orig. Grnd. = 1694.026

Des. Grd. = 1697.605

Subgrade = 1697.280

Orig. Grnd. = 1700.970

1702

1700

1698

1696

1694

J

K

M

L

Figure 3.3A – First 

example cross-section.

Figure 3.3B – Second 

example cross-section.
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Roadside

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3.3 INTERPRETING ENGINEERING VIEWS FOR REVEGETATION PLANNING

Road construction, management, and safety concerns result in distinct revegetation zones 

along roadsides. Properly interpreting plans helps defi ne where these zones may be and 

what types of vegetation may be established. While the sizes and characteristics will vary, the 

zones which parallel the road can be grouped into four categories. Zone 1 begins immediately 

adjacent to the road surface (black top) and includes the road shoulder (compacted gravel, 

coarse subsoil, etc.), the bottom of the drainage ditch, and portions of cut and fi ll slopes. This 

fi rst zone is generally considered to be up to 10 feet (3 meters) from the pavement edge and 

is often barren of vegetation due in part to herbicide application, road salts, frequent ditch 

cleaning, and/or mowing. Prior to revegetating Zone 1, determine how close local, state, and 

federal road managing agencies will allow vegetation to be established next to the road. 

Zone 2 begins at roughly 10 feet (3 meters) from the pavement edge and continues laterally 

to about 30 feet (10 meters). This zone may begin at the ditch bottom or at some point on a 

cut or fi ll slope, and may continue to the limit of the construction zone. Within Zone 2, grasses 

and forbs can thrive, but larger forbs, shrubs, and trees usually are not planted or encouraged 23

Plant clumping spacing

5-7 m apart

Distance (m)

Salmon River Road

4 m Plant

spacing

2 m Plant setback

02 4 6 8 10 12 14 16

Figure 3.4A – Example typical view.

Shrub / Tree

75 mm - 100 mm

compacted saucer

Planting soil

& fertilizer

Riprap Minimum slope

1:1.33 (h : v )

Planting hole to

reach subgrade

Geotextile Subgrade

Figure 3.4B – Example typical 

view of plant installation.
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due to safety, maintenance, and visibility issues. Beyond 30 to 50 feet (about 10 to 16 meters) 

from the pavement edge, Zone 3 begins in which larger forbs and shrubs can be planted. Past 

about 75 feet (25 meters) from the pavement edge, Zone 4 begins with largely unrestricted 

revegetation potential. Understanding these zones is necessary to coordinate revegetation 

with road management practices and safety considerations (Forman and others 2003).

To defi ne the zones and begin to interpret engineering plans for revegetation work, information 

from plan sheets and quantity tabulations is applied to the plan map as shown in Figure 3.5A. 

Each area can be considered a revegetation unit or subunit. An estimate of the area in each 

of these units can be calculated and used in determining how many seedlings or pounds of 

seeds will be needed. These criteria can be graphically displayed on a typical cross-section 

(Figure 3.5B). On this cross-section, the criteria can be expressed as follows: from 7 to 19 m, 

grasses/forbs will be hydroseeded; from 19 to 31 m, shrubs will be planted; and on obliterated 

roads, trees will be planted. The slopes given in cross-sections can help defi ne the types of 

revegetation methods available.

3.4 UNDERSTANDING TECHNICAL CONCEPTS AND TERMINOLOGY

The ability to understand and utilize the technical concepts and terminology that road engineers 

use is essential to revegetation planning. Not only is this invaluable in understanding what is 

happening on the project site, but it is necessary in order to describe where revegetation eff orts 

will be carried out. The section below introduces key technical concepts and terminology.

3.5 NEXT STEPS

The ability to read and understand construction plans and utilize road-related terminology 

will be helpful in all aspects of roadside revegetation. This ability enables the revegetation 

specialist to contribute eff ectively to road design and construction processes, as well as to 

communicate revegetation needs and goals to others involved with the project. Following the 

initiation phase is the four-step planning phase to create a revegetation plan.

24

18+800

R/W

R/W

R/W

R/W

18+90019+00019+10019+200

Culvert Obliterate

Old Road

Line to be

Constructed

99182 255434.166 1410786.002 1696.398

99183 255544.687 1410818.803 1701.670

99184 255862.861 1410840.869 1704.295

Name Northing Easting

CONTROL POINTS

Elevation

CP

CP

CP

CP

99182

99183

99184

N 3 ̊ 46' 49" E

Grasses & Forbs

Shrubs

Trees

Figure 3.5A – Interpretation of plan view showing revegetation zones.

31m 19m 7m 0 7m 19m 31m

Grass/forb

hydroseed

Grass/forb

hydroseed

Sta. 19+000

Planted 

Shrubs

Planted trees

Obliterated Road

Planted shrubs

Figure 3.5B – Cross-section showing revegetation zones as interpreted from 

engineering plans.
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Berm – A ridge of rock, soil, or asphalt, typically along the outside edge of the road shoulder, 

used to control surface water. It directs surface runoff to specifi c locations where water can 

be removed from the road surface without causing erosion.

Buttress – A structure designed to resist lateral forces. It is typically constructed of large 

riprap rock, gabions, or well-drained soil to support the toe of a slope in an unstable area.

Cross-Section – A drawing depicting a section of the road sliced across the whole width of 

the road. Can also apply to a stream, slope, or slide.

Cut Slope (Back Slope or Cut Bank) – The artifi cial face or slope cut into soil or rock along 

the inside edge of the road. 

25

Cut Slope

(Back Slope)

Through Cut

Fill Slope

(Embankment)

Shoulder

Culvert

Surface Course

Base Course

Subgrade

Travelled

Way

Figure 3.6 – Terms used to defi ne roads.

Figure 3.7 – Terms used to defi ne roads: cross-section.

Subgrade

Toe of Slope

Natural Ground

Roadway (Construction Limits)

Clearing Limits

Right of Way

Cut Slope (Back Slope)

Property LimitsProperty Limits

Clearing Limits

Clearing

Limits

Ditch

Surface Course

Base Course

Fill Slope (Embankment)

Shoulder

Roadbed

Traveled Way

CL

Shoulder

Road Concepts and Terminology

(Adapted from: Keller and Sherar 2003)

Road Components
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Cut-and-fi ll – A method of road construction in which a road is built by cutting into the 

hillside and spreading the spoil materials in adjacent low spots and as compacted or side-cast 

fi ll slope material along the route. A “balanced cut-and-fi ll” utilizes all of the “cut” material 

to generate the “fi ll.” In a balanced cut-and-fi ll design there is no excess waste material and 

there is no need for hauling additional fi ll material. Thus cost is minimized.

Ditch (Side Drain) – A channel or shallow canal along the road intended to collect water 

from the road and adjacent land for transport to a suitable point of disposal. It is commonly 

along the inside edge of the road. It also can be along the outside edge or along both sides 

of the road.

End Haul – The removal and transportation of excavated material off -site to a stable waste 

area (rather than placing the fi ll material near the location of excavation).

Fill Slope (Embankment Slope) – The inclined slope extending from the outside edge 

of the road shoulder to the toe (bottom) of the fi ll. This is the surface formed when 

excavated material is placed on a prepared ground surface to construct the road subgrade 

and roadbed template.

Grade (Gradient) – The slope of the road along its alignment. This slope is expressed 

as a percentage and is the ratio of elevation change compared to distance traveled. For 

example, a +4% grade indicates a gain of 4 units of measure in elevation for every 100 units 

of measure traveled.

Natural Ground (Original Ground Level) – The natural ground surface of the terrain that 

existed prior to disturbance and/or road construction.

Plan View (Map View) – View seen when looking from the sky towards the ground 

(bird’s-eye view).

Reinforced Fill – A fi ll that has been provided with tensile reinforcement through frictional 

contact with the surrounding soil for the purpose of greater stability and load carrying 

capacity. Reinforced fi lls are comprised of soil or rock material placed in layers with reinforcing 

elements to form slopes, walls, embankments, dams, or other structures. The reinforcing 

elements range from simple vegetation to specialized products such as steel strips, steel 

grids, polymeric geogrids, and geotextiles.

Retaining Structure – A structure designed to resist the lateral displacement of soil, water, 

or any other type of material. It is commonly used to support a roadway or gain road width 

on steep terrain. They are often constructed of gabions, reinforced concrete, timber cribs, or 

mechanically-stabilized earth.

Right-of-Way (ROW) – The strip of land over which facilities such as roads, railroads, or 

power lines are built. Legally, it is an easement that grants the right to pass over the land 

of another.

Road Center Line – An imaginary line that runs longitudinally along the center of the road.

Roadbed – Width of the road used by vehicles, including the shoulders, measured at the 

top of subgrade.

Roadway (Construction Limits or Formation Width) – Total horizontal width of land aff ected 

by the construction of the road, from the top of cut slope to the toe of fi ll or graded area.

Side-Cast Fill – Excavated material pushed on a prepared or unprepared slope next to the 

excavation to construct the roadbed. The material is usually not compacted.

Shoulder – The paved or unpaved strip along the edge of the traveled way of the road. 

An inside shoulder is adjacent to the cut slope. An outside shoulder is adjacent to an 

embankment slope.

Traveled Way (Carriageway) – That portion of the road constructed for use by moving 

vehicles including traffi c lanes and turnouts (excluding shoulders).

Through Cut – A road cut through a hill slope or, more commonly, a ridge, in which there is 

a cut slope on both sides of the road.

Through Fill – Opposite of a through cut, a through fi ll is a segment of road that is entirely 

composed of fi ll material, with fi ll slopes on both sides of the road. 26

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Road Structural Section and Materials

Borrow Pit (Borrow Site) – An area where excavation takes place to produce materials for 

earthwork, such as a fi ll material for embankments. It is typically a small area used to mine 

sand, gravel, rock, or soil without further processing.

Quarry – A site where stone, riprap, aggregate, and other construction materials are 

extracted. The material often has to be excavated with ripping or blasting, and the material 

typically needs to be processed by crushing or screening to produce the desired gradation 

of aggregate.

Surface Drainage

Armor – Rocks or other material placed on headwalls, on soil, or in ditches to prevent water 

from eroding and undercutting or scouring the soil.

Drainage Structure – A structure installed to control, divert, or move water off or across a 

road, including but not limited to culverts, bridges, ditch drains, fords, and rolling dips.

French Drain (Underdrain) – A buried trench, fi lled with coarse aggregate, and typically 

placed in the ditch line along the road, which acts to drain subsurface water from a wet area 

and discharge it to a safe and stable location. French drains may use variable sizes of rock 

but do not have a drain pipe in the bottom of the trench.

Inslope – The inside cross-slope of a road subgrade or surface, typically expressed as a 

percentage. Inslope is used to facilitate the draining of water from a road surface to an inside 

ditch. An insloped road has the highest point on the outside edge of the road and slopes 

downward to the ditch at the toe of the cut slope, along the inside edge of road.

Outslope – The outside cross-slope of a road subgrade or surface, typically expressed as a 

percentage. Outslope is used to facilitate the draining of water from a road directly off the 

outside edge of the road. An outsloped road has the highest point on the uphill or inside of 

the road and slopes down to the outside edge of the road and the fi ll slope. 

Riprap – Well-graded, durable, large rock, ideally with fractured surfaces, sized to resist 

scour or movement by water and installed to prevent erosion of native soil material.

Culverts and Drainage Crossings

Catch Basin – The excavated or constructed basin at the inlet of a culvert cross-drain pipe, 

used to store water and direct it into the culvert pipe.

Culvert – A drainage pipe, usually made of metal, concrete, or plastic, set beneath the road 

surface to move water from the inside of the road to the outside of the road, or under the 

road. Culverts are used to drain ditches, springs, and streams that cross the road. The invert 

is the fl oor or the bottom of the structure at its entrance.

27

Figure 3.8 – Culvert components.
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Headwall – A concrete, gabion, masonry, or timber wall built around the inlet or outlet of 

a drainage pipe or structure to increase inlet fl ow capacity, reduce risk of debris damage, 

retain the fi ll material, and minimize scour around the structure.

Inlet – The opening in a drainage structure or pipe where the water fi rst enters the structure.

Outlet – The opening in a drainage structure or pipe where the water leaves the structure. 

The outlet is usually lower than the inlet to ensure that water fl ows through the structure.

Miscellaneous Terms

Angle of Repose – The maximum slope or angle at which a granular material, such as loose 

rock or soil, will stand and remain stable.

Gabions – Baskets (usually made of wire) fi lled with rocks (or broken pieces of concrete) 

about 10-20 cm in size, used for building erosion control structures, weirs, bank protection, 

or retaining structures.

Road Decommissioning – Permanently closing a road through techniques that include 

blocking the entrance, scattering limbs and brush on the roadbed, replanting vegetation, 

adding waterbars, removing fi lls and culverts, or reestablishing natural drainage patterns. 

The basic road shape, or template, is still in place. The end result is to terminate the function 

of the road and mitigate the adverse environmental impacts of the road.

Road Obliteration – A form of road closure that refi lls cut areas, removes fi lls and drainage 

structures, restores natural contours, revegetates the area, and ultimately attempts to 

restore the natural ground shape and condition. Most adverse environmental impacts of 

the road are eliminated.

Silt Fence – A temporary barrier used to intercept sediment-laden runoff from slopes. It is 

typically made of porous geotextile material.

Streamside Management Zone (SMZ) – The land, together with the associated vegetation, 

immediately in contact with the stream and suffi ciently close to have a major infl uence on 

the total ecological character and function of the stream. It is a buff er area along a stream 

where activities are limited or prohibited.

28

Cut Slope

Inside Ditch

Culvert

Armored

Outlet

Inslope Road

Fill Slope

Figure 3.9 – Terms used to describe road slopes.
4 PLANNING PHASE ONE: ORIENT

4.1 INTRODUCTION

Careful planning is essential to the success of any roadside revegetation project. In this phase, 

the revegetation specialist will be oriented to the specifi cs of the project, and will perform the 

following tasks:

 · Determine revegetation objectives,

· Define revegetation units,

 · Select reference sites, and

· Define the desired future condition. 

It is important to fi rst defi ne the overall project objectives and translate them into what this 

will mean for revegetating the site. The objectives of revegetation are usually to initiate and/

or accelerate the process of natural succession along the roadside and establish native plant 

communities that can sustain themselves without intensive, ongoing human intervention 

(Brown and Amacher 1999; SER 2004). Revegetation objectives are usually stated in broad, 

general terms addressing revegetation, soil stabilization, beautifi cation, and other goals.

Once overall project and revegetation objectives are defi ned, the second step is orientation to 

the project site. The site should be mapped and revegetation units delineated. Revegetation 

units are distinct areas within the project that will have diff erent management strategies. 

A project consisting of sites with little variation in topography, soils, vegetation types, rainfall, 

and so on may comprise a single revegetation unit. Most project sites, however, contain 

diff erent soils, climate, and vegetation types, requiring the delineation of a number of distinct 

revegetation units.

The third step is to identify reference sites for each of the revegetation units. Reference sites 

serve as models for revegetation planning, and later for monitoring and evaluating project 

success (SER 2004). Reference sites are natural or revegetated areas that demonstrate a 

desirable trajectory of recovery. For roadside revegetation purposes, suitable reference 

sites have undergone some disturbance, but have revegetated over time with functioning 

communities of native plants. Reference sites illustrate desirable developmental pathways for 

the revegetation units.

Table 4.1 – Phase one of planning involves four steps.

Activity Defi nition

Step 1. Determine 

project objectives

Describe the general purpose and goals of the project as determined 

by societal, ecological, and transportation needs; environmental 

regulations; and other factors.

Step 2. Defi ne and 

map revegetation 

units

Classify areas within the project site that are similar enough to be 

appropriate for similar strategies and treatments. Homogenous sites 

will have only a few units; sites with greater diversity (diff erent soil 

types, microclimates, vegetation types, management needs, etc.) will 

have more revegetation units. Each unit should be distinct in terms 

of ecology, management requirements, or both.

Step 3. Select 

reference sites for 

each revegetation 

unit

Locate natural or revegetated areas that will serve as models for 

desirable recovery of native plant communities. One or more 

reference sites are identifi ed for each revegetation unit in the project 

area.

Step 4. Specify 

desired future 

conditions for each 

revegetation unit

Create specifi c, measurable goals for each revegetation unit, usually 

defi ned in terms of the percentage of vegetative cover, ground cover, 

species composition, and so on.

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The fourth and fi nal step is to defi ne the desired future conditions (DFCs) for each revegetation 

unit. Incorporating information from reference sites and other data, DFCs specify guidelines 

(percentage of vegetative cover, plant species, etc.) appropriate for each revegetation unit in 

the project area.

4.2 STEP ONE – DEFINE REVEGETATION OBJECTIVES

Overall project objectives drive the modifi cation and construction of roads. As discussed in 

Chapter 2, the project objectives usually involve goals of improving safety and effi ciency, 

as well as environmental health. Overall project objectives are translated into revegetation 

objectives. Revegetation objectives are the foundation of all revegetation eff orts. It is important 

to develop a clear set of revegetation objectives early in the planning phase. When these 

objectives are understood and expectations are clear, the development and implementation 

of a revegetation plan is easier and more successful. Most roadside revegetation projects 

share the common objective of initiating and/or accelerating the process of natural succession 

near the roadside in order to establish self-sustaining native plant communities (Brown and 

Amacher 1999; Clewell and others 2005). This objective usually refl ects larger project goals, 

stated in terms of protecting soil and water resources, enhancing beauty, and improving safety 

and function while protecting environmental health. Later in the planning process, these 

general objectives will be pursued through specifi c goals (stated as DFCs) that can be used to 

evaluate the revegetation project. Table 4.2 defi nes some terms commonly used in defi ning 

revegetation objectives. Clarifying whether the overall goal is reclamation or restoration, for 

example, is an essential distinction for defi ning revegetation objectives.

Table 4.3 illustrates some of the most common road-related revegetation objectives as they 

relate to societal goals. Most revegetation projects state several objectives to address both 

short-term and long-term outcomes. For example, short-term, immediate revegetation 

objectives on most projects include erosion control and water quality protection through mulch 

and vegetative cover. Long-term revegetation objectives might include exclusion of invasive 

weeds, visual enhancement, and establishment of healthy native plant communities through 

soil restoration. While short-term objectives might rely on quick-growing ground covers such 

as grasses and forbs, long-term objectives are often broadened to include such revegetation 

treatments as planting deep-rooted tree and shrub seedlings to stabilize roadsides, creating 

visual screens, and/or supporting sustained plant community development.

Revegetation objectives are often developed by the revegetation specialist and design team 

and are supported by, or integrated with, public documents such as Environmental Assessments 

or Environmental Impact Statements. The objectives sometimes originate from a state or 

federal agency, motivated by environmental concerns and regulations regarding water quality, 

erosion control, and vegetation establishment. At this stage, revegetation objectives will be 

broad and general. As the project evolves, objectives are translated into more precise and 

Table 4.2 – Terms Used in Defi ning Revegetation Objectives (adapted from Allen and others 1997).

Revegetation The goal is to reestablish vegetation on a disturbed site. This is a general 

term that may refer to restoration, reclamation, and rehabilitation.

Restoration This is the recreation of the structure and function of the plant community 

identical to that which existed before disturbance. Restoration’s goal 

is conservation, with the intention of maximizing biodiversity and 

functioning.

Reclamation This is the recreation of a site that is designed to be habitable for the 

same or similar species that existed prior to disturbance. Reclamation 

diff ers from restoration in that species diversity is lower and projects do 

not recreate identical structure and function to that before disturbance. 

However, a goal of long term stability with minimum input is implied.

Rehabilitation This process creates alternative ecosystems that have a diff erent 

structure and function from the pre-disturbance community, such as a 

park, pasture, or silvicultural planting.

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measurable goals (DFCs). After the installation is complete, DFCs and revegetation objectives 

will be utilized in monitoring, evaluating, and managing the project.

4.3 STEP TWO – DEFINE AND MAP REVEGETATION UNITS

The revegetation plan must include a map of the project area that displays the management 

areas, or revegetation units, where the various revegetation treatments will be applied. 

As the name implies, revegetation units are relatively homogenous areas that will receive 

similar treatments. Revegetation units are delineated management areas that represent the 

integration of similar site factors, such as soil, vegetation, and climate that will aff ect the 

revegetation potential of a site. Usually the revegetation units are based on site similarities. 

Projects containing diff erent ecological zones or in complex geologic terrain might have many 

revegetation units, while projects on more homogeneous sites may have only one or two 

revegetation units. Revegetation units also represent areas of similar revegetation objectives. 

If, for example, there are distinctly diff erent road objectives (beautifi cation objectives on one 

area versus erosion control objectives on another), a revegetation unit might be split into two 

revegetation units. Although the two revegetation units are similar from a soils and climate 

standpoint, they must be treated diff erently due to management considerations.

Table 4.3 – Common Road Revegetation Objectives.

Revegetation 

Objective 

Function of Native Plants

Erosion Control Controlling surface erosion and thereby protecting soil and water 

quality is a high priority on road construction projects. Native 

grasses, forbs, and other herbaceous plants can help meet this 

challenge, particularly when they are accompanied by appropriate 

mulching treatments. Deep-rooted native trees and shrubs can also 

enhance stability of cut and fi ll slopes.

Visual 

Enhancement

Vegetation is often used to enhance the aesthetic experience of the 

traveler. Wildfl owers add beauty in spring; deciduous trees change 

color in fall; and evergreen species stay green all year. Vegetation 

can also be used to hide structures such as gabion walls or slopes 

covered by riprap.

Weed Control Roadsides can be corridors for the transport and establishment of 

noxious or invasive weed species. Once established, weeds are hard 

to eradicate and become seed sources for further encroachment. 

Revegetating with desirable native species minimizes opportunities 

for problem species to establish.

Wildlife Protection Many roads intercept animal corridors. Techniques to make roads 

more permeable to wildlife (often via under- or over-passes) are 

being developed. The revegetation specialist can help by minimizing 

dangerous interactions between vehicles and wildlife. The presence 

of birds and small animals can be enhanced when appropriate plant 

species are reestablished.

Cost Management Advanced planning, an integrated approach, and the use of 

appropriate stocktypes and equipment all facilitate successful and 

cost-eff ective revegetation.

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4.3.1 Mapping

The revegetation unit map is developed by fi rst conducting a pre-fi eld evaluation of soil and 

vegetation using available information, including:

 · Road plans, including cross-sections and plan views for road construction;

 · Vegetation maps, plant association guides, and literature about the area;

 · Climate data and information; and

 · Soils maps, such as USDA Natural Resources Conservation Service (NRCS) soil surveys 

and USDA Forest Service Soil Resource Inventory.

Pre-fi eld research draws from existing site information and maps as much as possible. Print out 

all available maps that cover the road construction area. Soil and vegetation maps will delineate 

soil types and plant communities, and this information should be sketched or overlaid onto 

the road plans. Often the boundaries of soil types and plant communities will align, revealing 

distinct ecological areas within the project site. These mapping units form the preliminary 

designation of revegetation units.

Maps and other descriptive information about the project site can be obtained from a number 

of state and federal agencies. For example, on USDA Forest Service lands, vegetation maps can 

usually be found within the Forest Service GIS system. Existing and potential vegetation are 

often available as layers, and can be provided by the district silviculturist. There may also be 

some broadscale plant classifi cations and mapping units that have been done by the ecology 

group within the agency. For some areas, a Terrestrial Ecological Unit Inventory (TEUI) may be 

available on the internet. TEUI is a land survey system administered by the Forest Service that 

provides baseline ecosystem information on soils and vegetation to revegetation specialists 

and other land use planners.

4.3.2 Climate Information

Climate plays a dominant role in the success or failure of the revegetation eff ort. Knowledge of 

climate factors can help delineate the appropriate revegetation units and develop achievable 

DFCs. In later phases of the planning process, climate data will be utilized to determine 

appropriate revegetation treatments.

Obtaining climate records from a variety of sources is the fi rst step in conducting a climate 

assessment. Climate records for the western United States can be located at the Western 

Regional Climate Center website http://www.wrcc.dri.edu. This website contains the climate 

summaries for over 2800 climate stations (Figure 4.1). Clicking on the weather station will 

display data for each year the station has operated. Information can also be obtained from 

automated weather stations, called SNOTEL stations, that have been installed in remote areas 

to fi ll in weather information gaps. The records for these sites are located at the same website. 

While SNOTEL stations lack some of the reliability of staff ed stations (remote stations can break 

Examples of Defi ning Revegetation Units

1) Example One (Rock type): The site survey combined with pre-fi eld map research 

revealed that a planned road corridor crossed two very distinct soil types, one of soils 

formed from granite and another formed from sedimentary bedrock. Because plant growth 

will respond diff erently to these distinct soils, they represent two revegetation units.

2) Example Two (Climate): The road begins in a valley bottom, where the vegetation 

consists of moisture-loving species, and rises out of the valley to a side slope with species 

that thrive in hot, dry conditions. The vegetation change represents a signifi cant change in 

microclimate; therefore, two diff erent revegetation units were created.

3) Example Three (Aspect): The road cut creates a throughcut with steep south- and 

north-facing slopes. Because the vegetation capable of establishing on either aspect is 

quite diff erent, they are delineated as separate revegetation units.

4) Example Four (Landform): A proposed road crosses a fl at glacial bottom and then 

climbs the side of a steep glacial slope. Two revegetation units would be defi ned by the 

associated landform.

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down in the winter and not be fi xed until spring) and cover fewer years of data collection, 

the data is usually suffi cient for understanding the local climate of the project site. For many 

construction projects, a local weather station will not exist. In these cases, data from the nearest 

weather stations can be extrapolated to the project site. A computer model for extrapolating 

weather station data to a project site is located on the Forest Service WEPP erosion model 

website http://forest.moscowfsl.wsu.edu/fswepp under the heading Rock: Clime. This model 

allows the user to modify a base weather station on known parameters of the project site, such 

as elevation and site location.

4.3.3 Soils

Many counties in the United States have soils maps either completed or in the process of 

completion. These maps have been developed by the NRCS, and are available at the website 

http://soils.usda.gov/. This website contains over 200 soil surveys covering large portions of 

the western United States. If a soil survey is available for the project site, all soils maps covering 

the road construction area should be printed. Most soil survey websites will have the option 

to place a topographic map or orthographic photo as a base to a soils map (Figure 4.2B). Soils 

maps are a composite of soil mapping units with a number or letter within each unit. These 

alphanumeric codes correspond to a mapping unit narrative that can be found in the text 

Walla Walla

Seattle

Tacoma

153

Walla Walla

Figure 4.1 – Average monthly temperatures and precipitation can be obtained from internet 

sources such as the Western Regional Climate Center http://www.wrcc.dri.edu. The data from 

these stations can be extrapolated to the project site.

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associated with the survey. Locate the narrative for each of the mapping units transected by 

the road project. The narratives describe a typical soil profi le, list the native vegetation, defi ne 

the land uses for the soil, and summarize soil characteristics, such as water-holding capacity, 

permeability rates, pH, and soil depth. Most lands administered by the USDA Forest Service will 

have separate soils reports in addition to, or in lieu of, the NRCS soils report. These reports are 

often referred to as a Soil Resource Inventory (SRI) report, and can be obtained at the Forest 

Service district offi ce.

4.3.4 Site Survey

While information from published surveys, maps, or resource inventories is useful, it often does 

not provide the detail needed for defi ning and mapping revegetation units. A detailed survey 

of the project area will verify that preliminary revegetation unit mapping matches the realities 

in the fi eld. A site survey is usually carried out after the preliminary road location has been 

staked on the ground. The road location stakes are useful points for collecting site information 

because they have been surveyed and located on a preliminary road plan, and can therefore be 

easily referenced throughout the life of the project.

Your site survey should locate, verify, and refi ne the boundaries of the revegetation units on 

the ground. Walking the site with maps in hand is key to accurately defi ning revegetation 

units. When several resource specialists are involved in collecting site information, they should 

integrate their survey information to delineate the revegetation units.

After completing your walk-through, it is important to sit down with the highway project maps, 

pre-fi eld, and fi eld information. As you examine the information collected on soils, climate, 

and vegetation, the boundaries of revegetation units will probably seem clear. Areas with 

similar soils, climate, microclimates, and plant communities will be one unit. Management 

considerations may require that ecologically homogenous units be divided into several units if 

there are diff erent management goals. Revegetation units should now be sketched onto your 

project map.

Roadside ecological zones must also be considered when delineating revegetation units (See 

Chapter 3). Discussing long term objectives with those responsible for road maintenance and 

engaging in fi eld surveys will help defi ne these zones. Understanding the zones and their 

corresponding vegetation is necessary to defi ne revegetation units and set appropriate DFCs 

aligned with road management practices. Otherwise, you may be attempting to establish 

species that have no chance to survive due to roadside management practices, or you may 

underinvest in potential plant communities further out from the road margin that are important 

for healthier roadside ecology.

4.4 STEP THREE – LOCATE AND DESCRIBE REFERENCE SITES

Reference sites provide a reference, or natural model, for possible vegetation outcomes and are 

important for defi ning DFCs, as well as later monitoring and evaluation of the project following 

implementation (SER 2004).

Each revegetation unit should have at least one corresponding reference site that models some 

aspect of the DFC. The reference site shows how a revegetation unit might recover from disturbances 

at diff erent points in time after road construction. Reference sites can be considered as a snapshot, or 

series of snapshots, of possible future outcomes. They demonstrate a point in time along a desirable 

developmental trajectory of a plant community. Using reference sites to understand the possible 

vegetative outcomes after disturbances will help the revegetation specialist develop realistic 

expectations and provide a guide to the development of appropriate revegetation strategies. The 

revegetation specialist may sometimes choose to obtain baseline ecological data from several 

reference sites and then assemble DFCs from multiple references (SER 2004).

4.4.1 Disturbed and Undisturbed Reference Sites

Reference sites have similar site characteristics to the corresponding revegetation unit, but are 

in diff erent stages of plant succession. There are two types of reference sites: disturbed and 

undisturbed. For most road projects, suitable reference sites will be areas that are ecologically 

similar to the revegetation unit and have recovered from disturbances similar to those planned in 

the road construction project. Undisturbed reference sites may also be utilized when ecological 

restoration is an objective, or when suitable recovered reference sites are not available.

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Disturbed reference sites can be categorized several ways:

1) Type of disturbance;

2) Length of time after the disturbance; and

3) Desirability of the recovered vegetation.

Disturbed reference sites can be old road cuts and fi lls, abandoned roads, ground-based 

logging sites, waste areas, rock source sites, ski runs, or other areas that have recovered 

from past disturbances. Disturbed reference sites often show a range of possible vegetative 

outcomes years after disturbance. Some sites will show good recovery, including stable soil, 

visually pleasing, and populated by functioning communities of native plants. Others might 

show what can go wrong if revegetation is not carried out properly, including erosion, poor 

Figure 4.2 – Developing the Revegetation Map.

Figure 4.2B – Soils maps are available for most project sites if a soil survey has been completed 

for the county. Soils maps can be obtained from sources such as the U.S. Department of 

Agriculture http://soils.usda.gov/, or from contacting a NRCS offi ce. The codes are described in an 

accompanying soil survey report.

Figure 4.2A – The initial step in developing a revegetation map is to obtain topographic maps 

of the project area. These maps will then be overlaid with maps for soil, vegetation, ownership, 

and other relevant information.

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ground cover, weed infestation, and a lack of native vegetation. Understanding the conditions 

that lead to these vegetative outcomes can be a guide to avoiding this outcome in the future.

Disturbed reference sites are the best models to demonstrate what is possible on the site, what 

trajectories succession might take (with or possibly without human intervention), and ways 

to eff ectively intervene in order to facilitate desired outcomes. Disturbed reference sites are 

invaluable in developing realistic DFCs. Ideally, the type of disturbance on a disturbed site 

should match the type of road construction disturbance that will take place on the revegetation 

unit. For example, if the road cut after construction will be denuded of topsoil, then a disturbed 

reference site should be found that lacks topsoil.

The stage of recovery is also important. It is ideal to fi nd several disturbed reference sites 

that represent diff erent successional stages of site recovery. For instance, a revegetation unit 

Figure 4.2D – The proposed road location was surveyed on the ground by specialists in soils 

and botany. The survey identifi ed old disturbances that had revegetated naturally over the last 

50 years to a community of native grasses and forbs. Several disturbed reference sites (RR1, RR5 

and RR6) were identifi ed. Intensive soil and vegetation surveys were conducted at each site. 

For the new stretch of forest road, undisturbed reference sites (UR2 and UR4) were identifi ed 

and surveyed.

Figure 4.2C – In this example, a portion of an existing road will be reconstructed; a new road 

section will be constructed through a forested area; and the section of road that is not needed 

will be obliterated and revegetated.

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would ideally be represented by a recently disturbed site (several years after disturbance), a 

recently recovered site (5 to 25 years after disturbance), and a fully recovered site (over 25 years 

since disturbance).

While there is no such thing as a “pristine” plant community, an “undisturbed” reference site 

is an area that has not been heavily impacted by ground-disturbing activities. Undisturbed 

reference sites indicate the highest potential of a revegetation unit, and are most often used as 

models when the goal is not merely revegetation, but ecological restoration. The description 

of soil, climate, and vegetation in an undisturbed reference area can become the framework for 

the DFC. It provides the revegetation specialist an understanding of those site characteristics or 

components necessary for healthy ecological functioning. 

4.4.2 Locate Reference Sites

The process of selecting and describing reference sites is best accomplished in an 

interdisciplinary manner. Soils and vegetation specialists should work together to locate, 

select, and assess reference sites. The discussions that are generated during this process are 

generally far more thorough in knowledge and understanding of recovery processes than if 

surveys were conducted separately.

Prior to going to the fi eld to locate reference sites, a list should be made of all reference sites 

(age, prior disturbance, and desirability) needed for the analysis. Then, using road, soils, and 

vegetation maps of the area, possible locations for reference sites can be determined. Based 

on these maps, a “windshield survey” can be conducted by driving adjacent or connecting 

roads where potential reference sites might be found. Frequently stopping to get out of the 

vehicle and examine the site will ensure the sites are similar to the general characteristics 

of the revegetation unit. A search should be done for diff erent ages and plant communities 

on undisturbed and recovered reference sites. The reference site process will reveal the 

variation in the project area and will help you understand the best strategy for future surveys. 

Once reference sites are selected in the fi eld, they are identifi ed on a revegetation map to 

be surveyed.

Figure 4.2E – Based on the soil and vegetation data collected during these surveys, six 

revegetation units were identifi ed (colored areas). The criteria for diff erentiating these units and 

their treatments is described in the table below.

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Table 4.4 – Reference Sites Should Assessed with a Series of Surveys of Increasing Complexity.

What Where How Why

Prefi eld survey Offi ce Maps, contacts,

literature

Begin to identify species, 

communities, and 

successional processes;

determine scope 

of other surveys 

“Windshield”

Survey

Proposed Road 

Corridor, existing 

road and reference 

sites

Windshield/drive 

through

Get oriented; strategize 

fi eld survey

Field Survey Proposed road 

corridor, existing 

road and reference 

sites

Intuitive survey,

observe, identify, 

list

Develop comprehensive 

species list, conduct 

soil survey, defi ne 

plant communities and 

successional processes

Wet

Cold

Cool

Warm

Hot

Very Moist Moist Dry

Cold, Wet Cold,

Very Moist Cold, Moist Cold, Dry

Cool, Wet Cool,

Very Moist Cool, Moist Cool, Dry

Warm, Wet Warm,

Very Moist Warm, Moist Warm, Dry

Hot, Wet Hot,

Very Moist Hot, Moist Hot, Dry

Table 4.5 – Ecological settings 

in forested sites of the Blue 

Mountains of northeastern 

Oregon (Powell and others 1998).

4.4.3 Survey Reference Sites

Conducting a series of surveys (Table 4.4) will provide baseline ecological data and a vegetation 

inventory. The goal is to obtain suffi cient information from reference sites to realistically defi ne 

DFCs. During an initial survey, the appropriate survey intensity can be determined based on 

information needs and knowledge gaps. For example, if one of the revegetation objectives is to 

restore an abandoned road to a DFC similar to a neighboring forest, then a survey of vegetation 

and soils of an undisturbed and disturbed neighboring forest would be conducted to describe 

the site characteristics and species composition.

Prior to fi eld surveying of reference sites, the data used to defi ne revegetation units (See 

Section 4.3) should be reviewed. Information regarding land ownership, site history, resources, 

and past and current management is also valuable. Government specialists who might have 

knowledge of the soils, vegetation, climate, and hydrology, as well as locals who can provide 

insight on site history, should be contacted.

Your survey of reference sites should have 4 objectives:

1) Create a comprehensive species list,

2) Defi ne the plant communities,

3) Determine possible successional trends in the plant communities, and

4) Survey soils.

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4.4.3.1 Create a Comprehensive Species List

A good method for compiling a comprehensive species list is to choose a representative crosssection of the major habitats and topographical features, with the goal of identifying as many 

species as possible. This is accomplished by surveying only in areas of maximum diversity. This is 

sometimes called an “intuitively controlled survey” (Riley 2006). The intuitively controlled survey 

is appropriate for reference site descriptions because the method maximizes an understanding of 

species diversity. It should be noted that if there are a few species that cannot be identifi ed in the fi eld, 

samples should be collected in a plant press and brought back to the offi ce for identifi cation. If more 

detailed data collection is desired, transects or grids may be run to conduct a vegetation survey.

All observations during or immediately following fi eld surveys should be documented. Note if 

the species are native or introduced and keep track of species by general life form, including: 

trees, shrubs, annual grasses, perennial grasses, annual forbs, perennial forbs, sedges, and 

rushes. This information will be used later in Phase Three to develop a comprehensive species 

list for the project.

4.4.3.2 Describe Plant Communities

Species should be grouped by plant community and ecological setting. Ecological settings 

are based on characteristics of the site, which are usually a range of temperature/moisture 

conditions (Table 4.5).

Within each of these ecological settings, note each plant’s amplitude, or how often the species 

occurs across diff erent ecological settings. For example, a species that crosses eight ecological 

settings and is found in cold, wet through warm, dry environments would have a wide 

amplitude. Amplitude is usually quantifi ed in terms of abundance (e.g., stems per square foot), 

density (ground or canopy cover percentages), or other measures within a given ecological 

setting. See Phase Three for a detailed description of this process.

Next, note groups of species that commonly occur together within or across ecological settings. 

The goal of most projects is to revegetate not just individual species, but to develop healthy, 

functional communities of plants. Gather information that shows how each species fi ts into an 

assemblage or association of plants. These assemblages may be referred to as “plant associations,” 

“plant communities,” or “guilds.” In this manual, the term “plant community” will be used.

One method to defi ne plant communities and successional processes is to refer to agencycreated guides, such as a Plant Association Guide or equivalent. (A Plant Association Guide is 

available for each National Forest.) Based on species lists, density, canopy cover, and/or relative 

abundance, the Plant Association Guide allows you to key out the plant community in which 

you are working. The guide also supplies information on associated soil types, full species 

lists, climate ranges, and how each plant community might respond to diff erent types of 

disturbances. (For some roadside environments, it may be diffi cult to identify plant communities 

because species close to the road can consist of many non-native species.) Patterns of plant 

communities, their species, and their ages should be noted on a map.

Figure 4.3 – Successional processes and plant 

communities vary considerably based on site 

conditions. In this example, plant communities 

developed diff erently on north-facing and 

south-facing slopes.

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Visiting reference sites and adjacent areas of diff erent seral stages following a disturbance 

is invaluable in understanding successional processes and guiding revegetation eff orts. 

Characterizing the plant successional stages of the reference sites will be helpful. Categorize 

the plant communities into four categories: early, mid, and late seral, and climax. Figure 4.3 

illustrates how plant communities develop diff erently over time, depending on site conditions 

and successional processes.

4.4.3.3 Survey Soils

Understanding the soil characteristics on reference sites is essential to eff ectively defi ne DFCs. 

Although soils reports provide general information on soil characteristics, such as soil depth, 

pH, and water-holding capacity, intensive soil surveys should be conducted on all reference 

sites. Soil pits should be dug at each site and the following information collected for topsoil 

and subsoil:

 · Soil texture (See Section 5.3),

 · Rock fragments (See Section 5.3),

 · Rooting depth (See Section 5.3),

 · Topsoil depth (See Section 5.5),

 · Nutrient levels (See Section 5.5),

 · Soil structure (See Section 5.3),

 · Litter and duff layers (See Section 5.4),

 · Site organic matter (See Section 5.5), and

· Infiltration rates (See Section 5.2).

The process for collecting and interpreting this information is described in depth in Chapter 5 

(Planning Phase Two).

4.4.4 Describe Revegetation Units Using Survey Information

The process of describing revegetation units in detail is interpretive and predictive, rather than 

purely descriptive. You are attempting to defi ne the processes and species in a revegetation 

unit, using the snapshots obtained from the reference sites. Since each revegetation unit can 

have several reference sites, the data from these sites must be compiled, summarized, and 

interpreted. The following questions can help in understanding the ecological processes for 

revegetation of the site based on reference site information:

 · What is the generalized site (soil, climate, vegetation) description of each 

revegetation unit?

 · What are the ecological diff erences between revegetation units?

 · How will each revegetation unit respond to different types of disturbances immediately 

after construction, in one year, three years, and ten years?

 · What are the ecological trajectories for each unit and what are the dominating factors 

controlling them?

 · What are the limiting factors (discussed in detail in the next chapter)?

The answers to these questions should be summarized as an ecological description for each 

revegetation unit.

4.5 STEP FOUR – DEFINE DESIRED FUTURE CONDITIONS (DFCS)

Once revegetation units and corresponding reference sites have been identifi ed, mapped, 

and described, the desired future condition (DFC) can be defi ned for each unit. The DFC takes 

the overall revegetation objectives defi ned earlier and translates them into measurable goals 

tailored to each management unit. The DFC specifi es the desired or expected composition of 

vegetation at a defi ned point in time after the completion of the revegetation work. Roadside

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An example DFC would be, “2 years after seeding, vegetative ground cover will be 50%; of 

this cover, 75% will be composed of perennial native species.” Stating expectations in this 

manner will:

 · Clarify how the site will appear after treatments;

 · Narrow down the appropriate revegetation treatments; and

· Define measurable criteria, or thresholds, that can be used for monitoring project success.

Commonly stated DFC criteria include:

 · Vegetative ground cover (%),

 · Bare soil (%),

 · Native plant cover (%),

 · Seedling survival (%),

 · Seedling density (plants per area), and

 · Tree growth (height per year).

Stating the DFC in measurable terms and with a timeline ensures that the project team, 

regulatory agencies, and the public have similar expectations of how the project will unfold. 

Quantifying the objectives also allows monitoring to determine how well project objectives 

were met. For example, if one of the objectives is erosion control, a quantifi able criteria for a 

desired future condition might be, “bare soil one year after road construction will be less than 

20%.” If another objective is the establishment of native plants, then a measurable threshold 

for success might be, “native perennial grasses and forbs will occupy over 40% of the site within 

three years of seeding.” How to develop and implement monitoring and adaptive management 

is described in Chapters 11 and 12.

DFCs are stated within a time frame, which is commonly defi ned as the number of years after 

project disturbance. Defi ning DFCs usually takes into consideration how the revegetation units 

could look in both short-term (1-3 years) and long-term (5, 10, 15+ year) time frames. Asking a 

series of questions about the site’s potential future condition is an important part of the thought 

process. What might happen with no intervention or management? What might happen with 

massive intervention and mitigation? Between these two extremes, what are the key leverage 

points that might provide for healthy succession of the local plant communities with minimal 

human intervention after the road is constructed? How could various interventions be timed, 

from the beginning of the project through infusions of energy and resources a few years after 

establishment? From an ecological standpoint, what is the optimal future condition for the site 

in short- and long-term time frames? Given constraints and limitations, what is possible and 

feasible on the site?

Another key aspect of defi ning DFCs is refi ning your understanding of limiting factors regarding 

the types of native vegetation that you hope to re-establish. In Phase Two, a comprehensive 

assessment of limiting factors for general revegetation will be carried out. In Phase Three, more 

information about the local native species and their requirements will be gathered. As species 

and site information are analyzed, some factors will emerge as more limiting to particular 

vegetation types than others. For example, water input might be limited on the site. However, 

if native drought-tolerant species are planted, water will be less of a limitation than if you were 

using species that require more water.

Revegetation strategies should be developed that will set the trajectory during establishment 

to arrive where you want the site to be in 10 years. Site parameters that might limit long-term, 

not just short term, plant establishment must also be considered. When developing DFCs, think 

in terms of the plant succession that is likely to occur on each revegetation unit. In some cases, 

planting early seral species at the outset may work. By year 3, when the early seral species 

begin to decline, the late seral species may be increasing. In other cases, you may need to 

intervene several years after the early establishment phase of the project in order to support 

healthy succession. For example, short-term revegetation planning might call for seeding 

grasses and forbs to stabilize the site. One year later, the site might be revisited to remove 

any invasive species before they produce seeds. Two years later, the site might be revisited to 

interplant conifers and shrubs to meet long-term objectives. These three intervention points 

(seeding, weeding, and planting trees) speed succession in order to establish a sustainable 

plant community on the site.

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4.6 NEXT STEPS

With the revegetation units defi ned, reference sites described, and desired future conditions 

drafted, Phase One is complete and you are ready to move on to the next phases of the 

planning process. You will have more chances to reexamine and refi ne the DFCs in subsequent 

phases. For now, you can make an informed attempt at setting the DFCs for each revegetation 

unit, including specifying time and place. In Phase Two, the site attributes critical for plant 

establishment and long-term plant community development are described for each 

revegetation unit. The assessment of soils and climate made during the survey of reference 

sites should reveal if site characteristics are either obstacles to, or resources for, achieving DFCs. 

Based on the determination of limiting factors, a menu of the possible mitigating measures 

is developed. Once the limiting factors are understood, the vegetation is analyzed in greater 

depth in Phase Three. From the comprehensive list of species and plant communities present 

on the site, you will determine which species and groups are best adapted to the site and best 

suited to revegetation needs. Options for stocktypes and application methods are considered 

in order to achieve the best results. Finally, in Phase Four, all the elements are pulled together, 

selections are made, and recommendations are compiled into a comprehensive strategy and 

timeline for site treatments and revegetation strategies, or the Revegetation Plan.

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5 PLANNING PHASE TWO: ASSESS SITE

5.1 INTRODUCTION

Phase Two identifi es site factors that will limit revegetation establishment, defi nes the possible 

mitigating measures that can be employed to reduce the eff ects of limiting conditions on 

plant growth, and surveys those site attributes that can be used as resources to accomplish 

revegetation objectives. By the end of Phase Two, you should have:

 · Identifi ed limiting factors,

 · Considered mitigating measures for limiting 

factors, and

 · Assessed site resources.

5.1.1 Limiting Factors

Site conditions that aff ect plant establishment and 

growth are referred to as limiting factors. Odum 

(1971) defi nes limiting factors as “any condition which 

approaches or exceeds the limits and tolerance (of 

a plant species).” He further states that “the chief 

value of the concept of limiting factors lies in the 

fact that it gives the ecologist an ‘entering wedge’ 

into the study of complex situations. Environmental 

relations of organisms are apt to be complex, so 

that it is fortunate that not all possible factors are of 

equal importance in a given situation or for a given 

organism.” For the revegetation specialist, defi ning 

the limiting factors on any particular project or site 

is an essential process in developing a revegetation 

plan because it identifi es from a multitude of site factors only those that are roadblocks to 

successful revegetation. Not only does this simplify a complex analysis, it requires the 

revegetation specialist to systematically consider all site factors, focussing on those of greatest 

concern. For example, typical revegetation treatments conventionally call for the blanket use of 

fertilizers without assessing if nutrients are really limiting to plant growth. In many cases, other 

limiting factors to revegetation, such as low rainfall, compacted soils, low organic matter, and 

poor rooting depth, are more limiting. Without a comprehensive assessment of limiting factors, 

the prescription for fertilizer is akin to a physician prescribing medicine before the patient has 

been properly diagnosed. While soil fertility is often important on many highly disturbed sites, 

it might not be the primary limiting factor to revegetation on the site.

This manual has grouped the site characteristics essential for plant growth into nine limiting 

factors to revegetation typically encountered in the western United States. These factors are 

further broken down into component parts, or parameters (Figure 5.2). In this chapter each 

limiting factor to revegetation and corresponding parameters are discussed in terms of why 

they are important to plant establishment and growth, how they are assessed, and what 

mitigating measures can be applied to make them less limiting.

The information used in defi ning limiting factors for each revegetation unit can be obtained 

from the surveys and reports conducted in Phase One. In this process, it is important that an 

assessment of every limiting factor and corresponding parameter be made for each revegetation 

unit based on the expected condition of the site after disturbance. For this assessment, the 

types of post-construction disturbance must be clearly understood.

Mitigating measures are the site treatments that will reduce or eliminate the site conditions 

limiting to revegetation. There are usually several ways to mitigate each limiting factor. In this 

phase, mitigating measures are identifi ed and briefl y described for each limiting plant factor 

and parameter. While some of the mitigating measures might seem impractical for a particular 

revegetation project, they nevertheless should be considered in this part of the assessment. 

A process for developing the most appropriate set of mitigating measures into an integrated 

revegetation strategy will be covered in Phase Four.

Figure 5.1 – Limiting factors to 

revegetation can be displayed as unequal 

boards of a barrel. Water can only be held 

to the level of most limiting factor.

43
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Figure 5.2 – This manual recognizes nine site characteristics that can limit plant growth. These 

factors are further broken down into component parts, or parameters. 

Critical Plant Factors Parameters

Water 

Input

Precipitation

Interception

Infi ltration

Road Drainage

Water Storage 

and Accessibility

Soil Texture

Rock Fragments

Soil Structure

Rooting Depth

Mycorrhizal Fungi

Water 

Loss

Wind

Aspect

Competing Vegetation

Soil Cover

Nutrient 

Cycling

Topsoil

Site Organic Matter

Nitrogen and Carbon

Nutrients

pH and Salts

Surface 

Stability

Rainfall and Wind

Freeze – Thaw

Soil Cover

Surface Strength

Infi ltration

Slope Gradient

Surface Roughness

Slope Length

Slope 

Stability

Permeability

Restrictive Layer

Water Input

Slope Length

Slope Gradient

Soil Strength

Weeds

Weed Sources

Weed Growing Environment

Pests

Mammals

Insects

Human Interface

Disease

Road Maintenance

Recreational Use

1

2

3

4

5

6

7

8

9

44
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5.2 WATER INPUT

Water input refers to the moisture supplied to the soil through rainfall, snowmelt, and road 

drainage. This moisture recharges the soil and becomes the primary source of water for plant 

establishment and growth. Water input is infl uenced by obstacles that capture, or intercept, 

water before it can enter the soil, including standing live or dead vegetation and soil cover 

(litter, duff , and mulch). Surface infi ltration rates also regulate entry of surface water. If infi ltration 

rates are low, water that would normally enter the soil runs off the surface and is unavailable.

The primary site factors that aff ect water input are:

 · Precipitation,

 · Interception,

· Infi ltration, and

 · Road drainage.

In the western United States, water input is at its lowest levels from late spring through early 

fall. This is also the period when plants require the most soil moisture for survival and growth. 

During the summer, when water input is low, the soil profi le dries out as vegetation withdraws 

moisture. As soil moisture is depleted, plants cease growing; if soil moisture is not recharged, 

plants will go into dormancy or die. It is critical that any water from precipitation arriving during 

the dry season enters the soil and is stored for later plant use.

5.2.1 Precipitation

In wildlands revegetation, the only source of soil water comes through precipitation in the form 

of rainfall or snowmelt. In the western United States, this typically occurs from late fall through 

mid spring, during a period when plants are dormant and least able to utilize soil moisture for 

growth. Water that is not stored in the soil during these events is lost from the site either to 

ground water or runoff . The period when plants need soil moisture the most occurs during 

a fi ve to six month period, from April through October. For most sites in the western United 

States, the amount of moisture that occurs in this period is less than a quarter of the total 

annual rainfall.

Vegetation native to the western United States has evolved to compensate for the limited 

supply of moisture during the growing season (Figure 5.3). During the spring, when soils are 

charged with moisture from the winter precipitation and soil temperatures increase, plants 

produce new roots, followed by new foliage. As the soil dries out and plants undergo mild 

moisture stresses, new root and foliage growth cease. During the summer months, soil 

continues to dry and plants respond to even greater moisture stress by shutting down their 

physiological functions and becoming dormant. By mid to late summer, when available soil 

moisture is depleted and evapotranspiration rates are high, plants will show stress symptoms 

(browning, loss of needles and leaves); under extreme circumstances, plants will die. By late 

summer and early fall, rain returns and the soil slowly moistens again, reducing plant moisture 

stress and signaling plants to grow new roots.

Figure 5.3 – In the western 

United States, root and 

shoot growth occur when 

moisture is available in the 

spring. Growth ceases by early 

summer when there is very 

little rainfall. Root growth 

takes place again from late 

September through November 

when soils are recharged by 

fall rainstorms.

Roots

6

5

4

Jan

Precipitation (in)

Feb Mar Apr May Jun

Months

Jul Aug Sep Oct Nov Dec

3

2

1

0

Roots

Shoots

45
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The primary characteristic of precipitation for plant survival is the quantity of rainfall delivered 

in each storm event during the dry season. Storm events that deliver more than 0.25 inches 

of rainfall can wet the surface portion of the soil profi le and reduce plant moisture stress. 

Precipitation events that deliver less than this amount will rarely supply enough water to enter 

the soil, especially if interception and runoff rates are high.

5.2.1.1 Precipitation – How to Assess

Average monthly rainfall can be estimated by extrapolating climate data from weather stations 

closest to the project site (See Section 4.3.2 for how to access weather information). For more 

site specifi c information, precipitation can be collected on-site using rain gauges that capture 

and record precipitation.

There are two types of precipitation gauges available – digital and non-digital. The advantages 

of digital gauges are that they record the amount of rainfall and time that it occurred; the 

downside is cost (although prices are coming down). There are many types of digital rain 

gauges available, ranging in price and quality. It is important to select a digital rain gauge that 

is rugged, self-maintaining, and can record for long periods of time. 

Non-digital rain gauges are basically cylinders that collect and store precipitation while 

preventing evaporation. The gauges are monitored by simply measuring the water in the 

cylinder. The disadvantage of non-digital rain gauges is that they only report the rainfall that 

has occurred between site visits. They do not provide the dates when rainfall occurred and do 

not record rainfall intensities. 

5.2.1.2 Mitigating for Low Precipitation

Making the most of rain and snowmelt is an important part of successful revegetation 

planning. In most cases, supplemental watering will not be feasible. However, if very little water 

input occurs during the summer months, supplemental water on a temporary basis might be 

considered during plant establishment. This can take an active form, such as irrigation, or a 

passive form, such as redirecting surface water to planted seedlings.

Irrigation – Irrigation can be expensive, and it is generally used only on projects with high 

visibility or when rapid establishment is necessary for slope stability. These are projects 

where revegetation objectives include minimizing the risk of seedling failure or enhancing 

vegetation growth.

There are several basic types of irrigation systems used in roadside revegetation. They are 

grouped into fi xed systems, such as overhead sprinkler and drip irrigation, and manually applied 

systems. Fixed systems are discussed in Section 10.4.5.2, Drip Irrigation. Manual systems require 

water to be delivered directly to each plant, either from a hose or water container.

If only a few applications are necessary, the entire project can be done by hand. Personnel 

can water each seedling or seeded area using a water truck or hydroseeder (with water only), 

although care must be taken to avoid pulling hoses over establishing plants. Creating basins 

around seedlings will pond the surface-applied water and keep it concentrated in the seedling 

root zone. However, a better way to be certain that water will be delivered directly to the roots 

is to integrate the deep pot irrigation system into drip or manually applied irrigation methods 

(Bainbridge and others 2001). Pipes made from PVC or other materials are placed at depths of 1 

to 2 feet beside the seedling at the time of planting. The pipes are then fi lled with water when 

the soils dry out in the summer. The advantage of deep pipe irrigation is that water is delivered 

directly to the root system and, because the water is placed deeper in the soil, roots are forced 

to extend further into the soil for moisture. Refer to Section 10.4.5.1, Deep Pot Irrigation, for 

how to install this system.

For any irrigation method, it is important to monitor the wetting pattern of each irrigation. This 

will assure that water is applied at the appropriate rates. Digging a hole where the water has 

been applied at least one hour after irrigation will show how far the water has moved into the 

soil profi le. Duration of irrigations can be adjusted accordingly.

Water Harvesting – Water harvesting is the alteration of local topography to capture runoff 

water and concentrate it in areas where it can be used by plants. Water harvesting designs 

can be applied to roadside revegetation in several ways. They include, but are not limited to, 

46 contour bench terraces, runoff strips, and fi ll slope microcatchments. Contour bench terraces 
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are structures carved out of cut and fi ll slopes that collect and store runoff water. When fi lled 

with topsoil or amended soil, they are referred to as planting pockets. Figure 5.4 shows how 

planting pockets collect water. Fill slope microcatchments take advantage of water that drains 

off road surfaces and shoulders during intense rainstorms by capturing runoff in berms or 

depressions created at the base of the road shoulder (Figure 5.5). Shrubs and trees planted 

in these catchment areas will receive greater soil moisture. Even very low rainfall events, 

which would normally be of insuffi cient quantity to moisten the soil surface, can recharge 

soil in planting pockets and fi ll slope microcatchments. Sediments will also be deposited 

on the benches and pockets during rainstorms, building the soil up over time and reducing 

soil erosion.

5.2.2 Rainfall Interception

The amount of water entering the soil profi le from a rainfall event can be signifi cantly reduced 

by the interception of live or dead vegetation cover. Rainfall is captured through a series of 

layers, beginning with 1) the tree and shrub canopy, 2) ground cover, 3) litter, and 4) duff , and is 

returned to the atmosphere through evaporation. During the dry season, moisture from a low 

rainfall event might not reach to soil.

5.2.2.1 Rainfall Interception – How to Assess

Interception can be determined by the soil cover and vegetation that exist on the site after 

construction. In most cases, there will be very little vegetation and ground cover. It is therefore 

important to understand the eff ects of various types of ground cover used in revegetation on 

the rainfall interception. The depth and water-holding capacity of the material will determine 

the eff ect on water input.

Water-holding capacity of a material can be measured through testing labs specializing in 

composts. Alternatively, it can be measured by collecting the soil layer (duff , litter, mulch) and 

drying this material at 230 °F in an oven or crockpot with a meat thermometer stuck in the 

material. When the sample is dry (reaching 230 °F), it is placed in a 5-inch long by 3-inch round 

PVC pipe with the bottom secured with a fl at piece of cardboard to prevent the material from 

falling out. The PVC pipe is weighed and recorded, then placed in a bucket. The bucket is fi lled 

with water to the top of the pipe. The sample is removed and tipped upside down on a stack 

of paper towels to allow the water to drain. Wet towels are exchanged with dry towels until 

Figure 5.4 – Fill slope microcatchments 

take advantage of the low infi ltration 

rates of compacted fi ll slopes. Water 

moves off impervious road surfaces 

and compacted road shoulders during 

rainstorms (A), and is captured in 

berms or fl attened areas below the 

road shoulder (B). If this area is ripped 

and amended with organic matter, 

it becomes a very good environment 

for establishing shrubs and trees. 

Berms and/or fl attened areas are also 

catchments for sediments.

Figure 5.5 – Planting pockets are 

designed to capture water from upslope 

runoff (A), that collects in a slight 

depression (B). Captured water wets up 

the soil after each rainstorm and drains 

into the fractured bedrock (C). Soil is 

protected from surface erosion on the 

downhill side of the pocket with mulch or 

erosion fabric (D).
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towels are no longer wet. The pipe containing the material is reweighed. The material is then 

removed and the pipe plus bottom material is weighed. The moisture holding capacity of the 

material (by % dry weight) is: (wet weight - container) - (dry weight - container))/(dry weight - 

container)*100.

Figure 5.6 can be used to approximate how much rainfall is intercepted based on 

these parameters.

5.2.2.2 Mitigation for High Rainfall Interception

It is important to consider the water-holding capacities of the mulches to be used, especially 

on arid sites. Highly decomposed, fi ne textured composts have high water-holding capacities 

compared to coarser textured, less decomposed organic materials, such as bark, wood chips, 

and wood strands. Coarser materials allow more water to reach the soil.

5.2.3 Infi ltration

Infi ltration is the ability of the soil surface to absorb water from rainfall, snowmelt, irrigation, or 

road drainage. When infi ltration rates are slower than the amount of water applied to the surface 

of the soil, runoff will occur and this water will not be available for plant uptake. In addition, 

runoff can detach and transport soil, causing soil erosion and water quality problems. See 

Section 5.6.5 for a discussion of infi ltration rates on surface stability.

The size, abundance, and stability of soil aggregates in the surface soil determine the infi ltration 

rates. Large stable pores created by worms, insects, and root channels will absorb water quickly 

and have high infi ltration rates; soils that have been compacted, topsoil removed, or are low in 

organic matter will have poor infi ltration rates.

Under undisturbed conditions, infi ltration rates are typically high, especially where a litter 

and duff cover exists. When soil cover is removed, the impact from rainsplash can seal the soil 

surface, creating a crust that will signifi cantly reduce infi ltration rates. Infi ltration rates are also 

reduced when the soil is compacted by heavy equipment or traffi c.

5.2.3.1 Infi ltration – How to Assess

The most accurate method to measure fi eld infi ltration rates is using the rainfall simulator (See 

Figure 5.48). This equipment is calibrated to simulate the appropriate drop size and impact 

velocity of many rainfall events (Grismer and Hogan 2004). The rainfall simulator is expensive to 

operate and is not routinely used by the revegetation specialist. The most common application 

for this technology is in comparing diff erent mitigating measures, such as mulches and tillage 

methods, on infi ltration capacity. 

Without conducting rainfall simulation tests, infi ltration rates must be inferred by measuring 

soil strength, using a soil penetrometer, bulk density measurements (See Section 5.3.3), and 

from site characteristics such as visual observation of compaction and the percentage of soil 

cover. For most construction activities that remove surface cover or disturb the topsoil, it can 

be assumed that infi ltration rates will be reduced to levels that will create overland fl ow under 

most rainfall intensities.

3" thick

2" thick

1" thick

0 25 50 75

0

0.1

Rainfall Absorbed (inches)

Moisture Holding Capacity (% of dry weight)

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Figure 5.6 – 1 The amount of rainfall 

intercepted by soil cover (e.g., mulch 

or litter) is dependent on its waterholding capacity and thickness.

48
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5.2.3.2 Mitigating for Low Infi ltration Rates

Minimize Compaction – Driving heavy equipment over soils causes compaction and reduces 

infi ltration rates. After sites have been prepared for seeding or planting, heavy equipment must 

not be driven over soils. Such practices that are often recommended for erosion control, such 

as trackwalking, can actually decrease infi ltration rates and adversely aff ect the establishment 

and cover of native plants. These practices may not be appropriate on all soil types and should 

be assessed on a site specifi c basis (Hogan and Grismer 2007).

Tillage – Infi ltration rates can be increased through soil tillage, including subsoiling, ripping, 

and disking (See Section 10.1.2, Tillage). Tillage will, in most cases, reduce compaction and 

increase macro-pore space in the surface soil, as well as create surface roughness that further 

increases infi ltration rates. Depending on the stability of the surface material and the level of 

organic matter, the eff ects of tillage on infi ltration might only be eff ective for a short time. 

Concentrated water from road drainage has the potential to create deep gullies and must be 

avoided on tilled soils.

Organic Amendments – Incorporating organic amendments into the soil surface can create 

large, stable pores. However, unless the pores are interconnecting, they will not drain well 

(Claassen 2006). One method for creating continuous pores is to use long, slender organic 

material, like shredded bark or wood, composted yard waste, straw or hay (See Section 10.1.5, 

Organic Matter Amendments). Compared to short organic materials like wood chips, longer 

materials can increase infi ltration rates. Incorporating higher quantities of organic matter in 

the soil will also increase porosity because of the potential of the organic material to overlap 

and interconnect.

Mulch and Tillage – Applying mulch by itself does not necessarily increase infi ltration rates, 

although it can reduce sediment yields (Hogan and Grismer 2007). However, combined 

with surface tillage in the form of subsoiling or ripping, infi ltration rates can be signifi cantly 

increased. Mulch fi lls in the micro-basins left from the tillage operation (Figure 5.7).

Establish Vegetation – Ultimately, the best method to increase infi ltration is to create conditions 

for a healthy vegetative cover. Good vegetative cover will produce soils with extensive root 

channels, aggregated soil particles, and good litter layers.

5.2.4 Road Drainage

Roads intercept surface and subsurface water and, depending on how the road is designed, 

either disperse or concentrate this water. Dispersed water is often seen on outslope roads, 

where water moves in sheets over the road surface during rainstorms. Concentrated water 

occurs where runoff from the road surface and cut slopes, as well as intercepted water from 

seeps and streams, is collected in ditchlines that fl ow into culverts or other road drainage 

structures. These structures, in turn, deliver the concentrated water to slopes below the fi lls. 

Concentrated water is not always directed into creeks or natural drainage landforms. Therefore, 

during rainfall events and snowmelt, concentrated water might be directed onto soils that 

were drier before construction. The greater water input to these sites increases soil moisture 

and may change the type of vegetation that can survive and grow.

ABC

Figure 5.7 – Surface applied compost has greater surface area contact with the soil when it is 

applied to roughened surfaces (B), compared to smooth surfaces (A). Creating a rough surface 

prior to the application of composts creates better rooting, greater surface stability, and faster 

organic matter decomposition. Tilling the soil, through subsoiling and ripping, to depths of one 

to two feet (C) will break up compaction and create channels for compost to move into the soil, 

increasing soil contact and creating greater infi ltration rates.

49
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5.2.4.1 Road Drainage – How to Assess

Road drainage is assessed by identifying drainage structures on the road plans and visiting 

these sites in the fi eld during both pre- and post-construction. The outlets of culverts are the 

areas most likely to have concentrated water that can be considered for mitigation. Outslope 

roads and long road shoulders will produce sheet water.

5.2.4.2 Mitigating for Road Drainage

Species Selection – In areas below culverts, soil moisture should be higher than surrounding 

areas after rainstorms or snow melt. These areas should be evaluated to determine if more 

moisture-loving plant species should be sown or planted to take advantage of the increased soil 

moisture. However, be aware that, in arid climates, these sites may be as dry as the surrounding 

areas during long periods of summer drought. Consider placing obstacles, such as berms or 

large wood, at the base of culverts and perpendicular to the slope to slow concentrated water 

and increase soil moisture in these areas.

Biotechnical Slope Protection – Gullies can form below culvert outlets, and, for this reason, 

these sites are often armored with rock. Moisture-loving vegetation, such as willows, sedges, 

and rushes, can be integrated into the hardened surfaces as shown in Figure 5.8 and as discussed 

in Section 10.3.3, Installing Cuttings.

Water Harvesting – Road surfaces, shoulders, and to a lesser extent, cut and fi ll slopes are 

impermeable surfaces that create runoff water during precipitation. Utilizing this water can be 

considered a form of water harvesting. Figure 5.4 shows a simple way of using water off road 

surface and shoulders.

5.3 AVAILABLE WATER STORAGE AND ACCESSIBILITY

The previous section discussed how water enters the soil surface. This section describes how 

water is stored in the soil, and how soil water is accessed by roots. The total available waterholding capacity (TAWHC) is the sum of all water stored in the soil profi le that is available to 

plant roots. The amount of water that a soil can store is primarily a function of: 

 · Soil texture,

 · Rock fragments,

 · Soil structure,

 · Rooting depth, and

 · Mycorrhizae.

The amount of water a soil stores and how easily it is accessible by roots determines the types 

of species and the amount of vegetative cover a site can support.

Figure 5.8 – In gullies, draws, 

intermittent streams, or below culvert 

outlets, live willow stakes (See Section 

10.3.3.2, Live Stakes) are placed in rows, 

creating what is referred to as a live silt 

fence, to slow water velocities and catch 

sediment and debris (Polster 1997). The 

stakes root and establish into plants 

over time.

50
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SANDY

CLAY

CLAY LOAM

SANDY CLAY

LOAM

SILTY CLAY

LOAM

SILT

SILTY

CLAY

CLAY

90 10

80 20

70 30

60 40

50 50

40 60

30 70

20 80

10 90

100% Sand 90 80 70 60 50 40 30 20 10

100% Clay

100% Silt

LOAM

SILTY LOAM

LOAMY SANDY LOAM SAND SAND

% Sand

A

B

% Clay

% Silt

Figure 5.9 – The soil textural triangle defi nes 12 textural classes based on the percentage of 

sand, silt, and clay in a soil sample. The textural classes make it easy to describe soils without 

having to state percentage of sand, silt, and clay. To use the textural triangle, locate the 

percentage of sand on the bottom side of the triangle and trace the line up to the left hand side 

of the triangle. Do the same with either the silt or clay percentages on the other two sides of the 

triangle (follow silt diagonally down to the lower left and clay across from left to right). Where 

the two lines intersect is the textural class for that soil. For example, a soil with 75% sand and 

15% clay would be a sandy loam (A). A soil with 30% clay and 35% silt would have a clay loam 

texture. Adapted from Colorado State University Extension Publication (GardenNotes #214 at 

http://www.ext.colostate.edu/mg/fi les/gardennotes/214-EstTexture.html). 

51

5.3.1 Soil Texture

Soils are composed of minerals of varying sizes, ranging from clay (the smallest) to stone 

(the largest). Each mineral particle in a soil sample can be grouped into six categories depending 

on its size: clay (<0.00008 in [0.002 mm]), silt (0.00008-0.002 in [0.002 to .05 mm]), sand 

(0.002-0.08 in [0.05 to 2.0 mm]), gravel (0.08-3.0 in [2 mm to 8 cm]), cobble (3-8 in [8 to 20 cm]) 

and stone (>8in [20 cm]). The fi ne soil fraction is composed of a combination of sand, silt, and 

clay size particles. The proportion of these size groups in a soil is called the soil texture.

Figure 5.9 shows 12 soil textural classes by their proportions of sand, silt, and clay as defi ned by 

the U.S. Department of Agriculture classifi cation system (Soil Survey Staff 1975). There are two 

other soil classifi cation systems, American Association of State Highway and Transportation 

Offi cials (AASHTO) and the Unifi ed Soil Classifi cation systems, which are used for geotechnical 

engineering. These two systems use diff erent particle size ranges and include parameters such 

as liquid limit and plasticity in classifying soils. There is no accurate way of converting values 

from these systems to the USDA textural classes.

Soil texture is an important function of soil water storage because the unique arrangement 

of pores created in each texture class holds diff ering quantities of moisture. Clays are typically 

thin, wafer-like particles with highly charged surface areas that retain large amounts of water. 

Clay particles are often arranged to form small void spaces, or micropores, that also store water. 

Sands, on the other hand, are large, rounded particles that have a very low surface area and 

therefore do not hold as much water. The large pores (macropores) that are created when sand 

particles are adjacent to each other are good for air and water fl ow, but poor for storing water. 

Soils high in silts hold more water than sands because of the greater quantity of micropores. 

However, silt particles are not charged, therefore holding less water than clays.
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Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

No

No

No

Yes No

No Yes

Yes

No

Yes

Sand

Loamy Sand

Sandy

Loam

LOAM CLAY LOAM CLAY

Sandy Clay

Loam

Clay

Loam

Sandy

Clay

Loam Clay

Silt

Loam

Silty Clay

Loam

Silty

Clay

Forms a weak

ribbon less

than 1" before

breaking

Forms a ribbon

1-2" before

breaking

Forms a ribbon

2" or longer

before breaking

Does it feel

very gritty?

Does it feel

very smooth?

Does it feel

equally gritty

and smooth?

Start: Place soil in palm of hand. Add water slowly and knead the soil into a smooth and

plastic consistency, like moist putty.

Does the soil remain in a ball when squeezed?

Place ball of soil between thumb and fore nger, gently compressing 

the soil with the thumb, squeezing it upward into a ribbon. Form a 

ribbon of uniform thickness and width. Allow ribbon to emerge and 

extend over the fore nger, breaking from its own weight.

Does the soil form a ribbon?

Add more water

Is the soil too dry?

Add dry soil

Is the soil too dry?

What kind of ribbon does it form?

Figure 5.10 – Soil texture by feel method. Adapted from Colorado State University 

Extension Publication (GardenNotes #214 at http://www.ext.colostate.edu/mg/fi les/

gardennotes/214-EstTexture.html).

52

5.3.1.1 Soil Texture – How to Assess

Soil texture can be determined fairly accurately in the fi eld using the “feel” test. This is done 

with the aid of a soil sieve (2 mm opening size) and a bottle of water. Obtain a fairly dry fi eld 

sample and separate the fi ne fraction from the coarse fragments with the sieve (note the 

volume of gravel in the sample). Take a sample of the fi ne fraction in the palm of the hand and 

moisten it with water. The soil is rubbed between the fi ngers and thumb and classifi ed using 

the decision tree in Figure 5.10.

For a more exact determination of soil texture, a sample of soil can be sent to a soils laboratory 

for a particle size distribution test. This test will report the percentage of sands, silts, and clays 

in the sample. Published soil surveys of the project area will also give a reliable classifi cation of 

the soil texture.
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2

1.5

1

0.5

0.7

0.9

1.4

2 2.1

2.3

0

Available Water Holding Capacity

(inches per foot depth)

Soil Textural Classes

Sand

Loamy sand

Sandy loam

Loam

Sandy clay, silty clay, clay

Silt loam, clay loam

sandy clay loam

Figure 5.11 – General relationship between soil texture and available water-holding capacity. 

As clays increase in a soil, so does water-holding capacity. Typically, clay loam soils hold more 

than twice as much water as sandy textured soils (adapted after Ley and others 1994). The 

presence of humus in topsoil increases water-holding capacity of loams and sandy loams 

at a rate of 2.25% water to each percent rise in soil humus (Jenny 1980) which equates to 

approximately 0.75% increase in water for every 1% increase in organic matter.

53

Knowing soil texture is essential for estimating the available water-holding capacity (AWHC) of a 

soil. Figure 5.11 shows some typical available water-holding capacities for various soil textures. 

The values in this fi gure are generalized, but are acceptable for making recommendations on 

most revegetation projects. For a more accurate assessment, samples can be sent to soils labs 

for moisture determination. This is a specialized test and not all labs off er this test; therefore it 

is important to contact the lab prior to collecting samples. You can also measure water-holding 

capacity by the methods outlined in Inset 5.1.

5.3.1.2 Mitigating for Textures with Low Water-Holding Capacities

Organic Amendments – Incorporation of organic amendments (e.g., compost) can increase the 

water-holding capacity of a soil. Because the water-holding capacity of each type of organic 

matter varies by composition and degree of weathering, the eff ect on soil water-holding 

capacity by any organic matter being considered must be assessed prior to application (See 

Section 10.1.5, Organic Matter Amendments for assessment methods). Sandy textured soils 

benefi t most from organic matter additions, especially those with plant available water of 9% 

or less (Claassen 2006), which are typically sands, loamy sands, and sandy loam soils. Testing 

several diff erent rates of incorporated organic matter on soil moisture-holding capacity should 

be done to prior to selecting the source and the amount of material to apply.

Clay – The water-holding capacity of sandy textured soils can be increased by incorporating 

clay loam, sandy clay loam, and silty clay loam textures in the soil. The addition of clays should 

be at rates that result in new soil textures similar to loams, silt loams, or sandy clay loams. 

Higher rates of clay addition are not recommended. It is always important to test the additions 

of any soil to another to understand what the eff ects on water-holding capacity and structure 

might be. Ideally this should be in the fi eld in small plots.

Polyacrylamides – Polyacrylamides are hydrophilic polymers that absorb many times their 

weight in water. They have been used to increase the water-holding capacity of greenhouse 

growing media. The use of polyacrylamides as a measure to improve impoverished soils 

associated with road construction, however, has not been demonstrated. The uncertainties 

of using polyacrylamides range from which of the many products on the market to use, the 

method of application, the life span under fi eld conditions of each product, the eff ects of 

salts and minerals on water-holding capacity, and the amount of material to use. If the rate of 

polyacrylamide application in the soil is too high, the polyacrylamide granules will swell into 

25

2

1.5

1

0.5

0.7

0.9

1.4

2 2.1

2.3

0

Available Water Holding Capacity

(inches per foot depth)

Soil Textural Classes

Sand

Loamy sand

Sandy loam

Loam

Sandy clay, silty clay, clay

Silt loam, clay loam

sandy clay loam

Figure 5.11 – General relationship between soil texture and available water-holding capacity. 

As clays increase in a soil, so does water-holding capacity. Typically, clay loam soils hold more 

than twice as much water as sandy textured soils (adapted after Ley and others 1994). The 

presence of humus in topsoil increases water-holding capacity of loams and sandy loams 

at a rate of 2.25% water to each percent rise in soil humus (Jenny 1980) which equates to 

approximately 0.75% increase in water for every 1% increase in organic matter.
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the macropores, displacing soil air and creating anaerobic soil conditions (Cook and Nelson 

1986). If the rate of application of polyacrylamides is too low, there is a good chance that there 

will not be much benefi t to the soil. Fertilizers and minerals can reduce the amount of water 

being held (Wang and Greg 1990). Any full scale use of polyacrylamides should be tested at 

diff erent rates on the site being revegetated. The best candidates for testing these products 

would be sandy textured soils.

5.3.2 Rock Fragments

Mountainous soils and highly disturbed sites are typically high in rock fragments. The presence 

of rock fragments is important because the rock reduces the amount of water and nutrients a 

soil can hold. At high volumes in the soil, rock fragments will limit the composition of species 

and vegetative cover a site can support.

The rock classifi cation system classifi es rock fragments into fi ve size ranges: fi ne gravels 

(.08 to 0.2 in), medium gravels (0.2 to 0.8 in), coarse gravels (0.8 to 3 in), cobble (3 to 10 in) and 

stone (>10 in). 

Highly weathered rock can retain some soil moisture depending on the size of the rock 

fragments and degree of weathering (Flint 1983). For practical purposes, however, it is usually 

assumed that the presence of cobbles and stone rock fragments in the soil will reduce the 

available water-holding capacity of the soil proportionally. For example, a sandy loam soil 

without rock fragments has a water-holding capacity of 1.4 inches per foot of soil (Figure 5.11). 

When 30% large rock fragments are added to the soil profi le, the available water-holding 

capacity is reduced to 70% or 0.98 inches of available water (1.4 * 0.7 = 0.98). Fine and medium 

gravels (0.08 to .8 inches in diameter), on the other hand, hold some moisture. A rule of thumb 

is that these fi ne and medium gravels reduce water-holding capacity by two-thirds of their 

volume. In the above example, if 30% of the soil were composed of medium and fi ne gravels, 

the available water in this soil would be 1.12 inches per foot (1.4 - (1.4 * 0.3 * 0.66)).

5.3.2.1 Rock Fragments – How to Assess

Rock fragment content is usually determined in the fi eld during soil surveys or soil sampling for 

laboratory analysis. Large rock fragments, such as cobble and stones, are estimated in a variety 

of ways. The most common methods are surveying freshly exposed road cuts or observing 

soil excavation during road construction. Estimating the volume can be diffi cult, and often the 

amount of rock is over- or under-estimated. One method of estimating large rock in road cuts is 

to take a digital picture and lay a grid over the surface, as shown in Figure 5.12. Whenever rock 

is estimated from old road cuts, it must be discerned whether a portion of the rock is masked 

by soil that might have moved over the rock. This is why it is best to observe freshly exposed 

road cuts.

Inset 5.1 – Measuring Available Water-Holding Capacity in the Field 

(modifi ed after Wilde and others 1979)

Available water-holding capacity (AWHC) can be measured in the fi eld by collecting 

soil samples from a reference site or disturbed site in mid to late summer when soils are 

presumably as dry as they can be. For determining AWHC for undisturbed soils, samples 

are collected in bulk density rings in the same manner as sampling for bulk density (See 

Section 5.3.3). After removing the rings from the soil, cardboard or plastic is secured at each 

end of the rings to keep the soil from falling out. Rings are placed in airtight plastic bags to 

ensure that the samples stay intact during transport. The samples are weighed and placed 

in a bucket and fi lled with water to just the top of the ring. The sample is allowed to saturate 

with water. After you see glistening at the surface (indicating the soil is fully saturated), the 

ring is removed and placed upside down on paper towels and allowed to dry (soil surface 

should be in direct contact with towels). When paper towels become saturated with water, 

they are removed and replaced with dry towels. After 24 hours paper towels should not 

be saturated with water when in contact with the soil. The ring is then weighed. Available 

water-holding capacity (inches of available water per foot) = (wet weight – dry weight)/volume 

of cylinder * 12. For disturbed soils, the sample can be collected in an airtight bag and placed 

in a cylinder of known volume (placed fi rmly in the cylinder). The test is conducted from this 

point on as described above.
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Rock encountered while digging a soil pit will give a more accurate estimate of larger coarse 

fragments. Cobbles and stones, if they can be moved, are set apart from the soil when the pit 

is excavated. The volume of cobbles and stones is then visually compared to the volume of soil 

excavated from the soil pit to estimate the percentage of rock fragments.

Gravel content is determined from the excavated soil by sieving it through several soil sieves. 

Sieves are available through most engineering equipment companies (Figure 5.13). The 2 mm 

sieve (also referred to as a #10 sieve) is the most important sieve to use because it separates 

the gravels from the soil fraction. Another useful sieve is the 3/4 inch sieve because it separates 

the fi ne and medium gravels from the coarse gravels. This sieve can be used in the fi eld to 

remove larger rock fragments from the soil sample to reduce the volume. Finer sieving can be 

done back at the laboratory with a 2 mm sieve. If the soils are dry, this can be done in the fi eld. 

When soils are moist, they must be air dried fi rst before they can be sieved. The gravel and 

soil fractions are weighed and the gravel weight is divided by the weight of gravel plus soil 

(multiplied by 100) to determine the percent gravel.

It is important to remember to include the volume of cobbles and stones estimated in the fi eld 

with the gravels determined through sieving to calculate the total rock fragments in a soil:

% rock fragments in profi le = (100 - % cobbles and stone) * % gravels in sample

For example, a soil is estimated to have 25% cobbles and stones from observing road cuts and 

from several soil pits. Sieving shows that 50% of the sieved soil is composed of gravels. The soil 

would be composed of 25% cobbles and stones, 37.5% gravels ((100 – 25) * .50), and 37% soil.

5.3.2.2 Mitigating for High Rock Content

Rock Removal – Removing rock fragments from the soil will increase the available waterholding capacity of a soil. This can be done through screening and reapplication of the screened 

A B C

Figure 5.13 – The number 10 sieve 

(2mm opening) on the right separates 

soil particles (C) from rock particles (B 

and A). The 3/4 inch sieve on the left 

separates the fi ne and medium gravels 

(B) from the coarse gravels (A).

Figure 5.12 – The amount of rock 

in a section of soil can be roughly 

estimated from road cuts. Large rock 

can be determined by laying a grid of 

20 circles over a photograph of a road 

cut and recording the number of circles 

intercepting rock (in the center of the 

circle). This value is divided by the total 

number of circles in the grid to obtain 

the percentage of subsoil in rock 

fragments. In the picture below, subsoil 

contains approximately 25% large rock 

(5 intercepted rocks divided by 20 points).
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material. Screened subsoil should be kept separate from topsoil in this operation. The greatest 

benefi t from screening would be with soils that are very high in cobble and stone, where the 

reduction in volume of rock in the soil would be signifi cant. The “grizzly feeder” acts as a giant 

sieve to sort rock from soil. Rocky soil is dropped on the surface of the grizzly and fi ne soil falls 

through the screen while the rock fragments roll to the side through gravity or vibratory action, 

depending on the type of grizzly.

Incorporate Compost – Compost incorporated in the soil at high rates will increase the waterholding capacity of a rocky soil (See Section 10.1.5, Organic Matter Amendments). Depending 

on the size of the coarse fragments, incorporation can be diffi cult.

Surface Apply Compost – A more practical method to mitigate for rocky soils is to apply 

composts to the soil surface without mixing. When surface applied, composts can be good 

growing media for seeds of grasses and forbs (See Section 10.1.3, Mulches). At rates of greater 

than 3 inches applied to the surface, seeds can germinate well and establish into seedlings that 

can access moisture and nutrients not only from the compost, but also some moisture from the 

rocky soil below the compost.

Apply Topsoil – If topsoil is available, it can also be applied over a rocky soil (See Section 10.1.4). 

Topsoil depth will have to be placed deep enough to compensate for the quantity of rock in 

the soil being covered.

Planting Islands – On very rocky sites, mitigation of rocky soils can be accomplished by 

focusing mitigating measures into planting islands (See Section 10.1.8.4). Topsoil application, 

compost additions, or rock removal can occur in mounds, pockets, or benches strategically 

located throughout a revegetation unit and then planted with trees and shrubs.

5.3.3 Soil Structure

Just as soils are composed of many-sized mineral particle sizes, they are also composed of 

diff erent size voids, or pores, whose infl uence is responsible for water movement, water storage, 

air fl ow, and root penetration. Small pores (micropores) strongly infl uence soil moistureholding capacity, while large pores (macropores) are responsible for water movement, air fl ow, 

and root penetration. The arrangement of large pores is called soil structure. It is qualitatively 

observed as cracks, channels, aggregates, crumbs, and clods in the soil, and described by 

alternative terms such as friability and tilth. Water fl ow and root penetration depend on good 

soil structure. If soil structure is poor or compacted, roots are less able to penetrate the soil to 

access the water. Soil structure is important for other soil functions such as air fl ow, drainage, 

permeability, infi ltration, and as essential habitat for soil life. Soils with good structure are 

typically very productive.

Soil structure is signifi cantly reduced by heavy equipment on soils. The pressure applied by the 

equipment compacts the macropores (large pores), reducing soil volume and increasing soil 

density. This impact is called soil compaction (Figure 5.14). The eff ects of soil compaction on 

tree growth are well documented (Poff 1996). Trees growing on highly compacted soils have far 

less root, stem, and leaf production than those growing on non-compacted sites. Studies have 

shown a linear relationship between the increase in surface soil bulk density and decrease in 

height growth of young Douglas-fi r and ponderosa pine trees (Froehlich and McNabb 1984). 

Figure 5.14 – Compacted soils are 

created by heavy equipment operating 

over soil. The large pore spaces are 

compressed and the soils often 

form a platy structure as shown in 

this photograph.
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It should be assumed that soils will be highly compacted after construction due to the use 

of heavy equipment. In addition to reducing the potential of a construction site to grow 

vegetation, compaction increases runoff and sedimentation in rainstorm events. During the 

growing season, this means there will be less water entering the soil after rainstorms.

Compaction can occur several feet below the soil surface, depending on the type and weight of 

the equipment, soil texture, and soil moisture content. Very compacted strata can signifi cantly 

reduce or eliminate root penetration. Where compacted strata occur, downward water 

movement is restricted and water may saturate the soil layers above the compacted layer. 

The resulting saturated soil conditions can be very restrictive to root growth because of the 

lack of oxygen and the propensity for higher incidence of disease (Steinfeld and Landis 1990) 

and ultimate mortality (Figure 5.15). Compacted layers will naturally recover to their original 

porosity through root penetration, animal activity, and freeze-thaw events, but recovery can 

take 20 to 70 years (Wert and Thomas 1981; Froehlich and others 1983).

5.3.3.1 Soil Structure – How to Assess

It is easy to diff erentiate good soil structure from compacted soil (Figure 5.14) by touch or sight, 

but measuring it quantitatively is diffi cult. There are several indirect fi eld tests to quantify soil 

structure. These include bulk density and penetrometer tests. It is important to consider that 

exact soil measurements are less important than recognizing that after construction, most soils 

will be compacted. Nevertheless, these tests are good to perform when there is a question 

of degree of compaction, during reference site assessment, or when assessing the eff ects of 

revegetation treatments over time.

The bulk density test measures the dry weight of a standard volume of soil. If the soil has a 

high porosity, the bulk density values will be low; if the soil is compacted, the bulk density will 

be high. In this method, a cylindrical tube is driven into the soil with a portable bulk density 

sampler and a soil core is removed. The soil is shaved evenly on both ends so that the soil is 

exactly the shape and volume of the cylinder. The soil is then removed from the cylinder, ovendried and weighed.

Figure 5.15 – Compacted soils drain very 

slowly, as the puddles on the surface of 

the obliterated road in this photograph 

indicate. During rainfall or snowmelt, 

soils can stay saturated for days and 

even weeks. Establishing seedlings 

during this period can be very diffi cult 

because roots cannot survive when soils 

are poorly drained. Seedlings shown 

in this photograph were dead within 

three months.

Figure 5.16 – A soil core is used to 

determine bulk density and available 

water-holding capacity.
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Bulk Density = weight of soil (g) / cylinder volume (cc)

Bulk density values of a disturbed site must be related back to the bulk density of an adjacent 

reference site to make the values meaningful. Remaining within a 15% increase in bulk density 

over reference site values is ideal. Unfortunately, the bulk density method is time consuming 

and cannot be conducted on soils with high rock fragments.

A less quantitative, but more practical, method of measuring soil porosity is with a soil 

penetrometer. This equipment measures soil strength instead of density. Compacted soils 

have greater strength, and greater resistance to penetration by a penetrometer, than noncompacted soils. There are several types of penetrometers that can be purchased for fi eld 

work—penetrometers that measure the resistance as a continuous pressure is applied to the 

probe and penetrometers (impact penetrometers) that measure the number of blows of a 

hammer to drive the penetrometer into a specifi ed depth. A monitoring protocol for assessing 

compaction using an impact penetrometer has been developed by the NRCS (Herrick and 

others 2005b). The most practical and economical fi eld method for assessing compaction, 

however, is simply using a long shovel as shown in Figure 5.17. In this method, a site is traversed 

and, at predetermined intervals, a shovel is pushed into the ground to determine how loose 

the soil is. By applying the entire body weight to the shovel and observing the distance the 

shovel penetrates the soil, a qualitative measurement of soil compaction can be made. A rule 

of thumb is that a shovel penetrating over 12 inches deep indicates that a soil has a very high 

porosity; penetration below 3 inches deep indicates a very low porosity. 

Whether a shovel is used or a soil penetrometer, the readings are aff ected by rock content and 

soil dryness. When soils are dry, they have more strength and higher resistance to penetration. 

This is why any comparative sampling using a penetrometer must be done at the same moisture 

levels. Encountering rock poses an obvious problem to the use of penetrometers. It can be 

overcome by moving the penetrometer around until a point is found where the penetrometer 

can be applied without hitting rock.

Penetrometer values for disturbed sites must be evaluated against those from reference sites 

for comparative analysis.

5.3.3.2 Mitigating for Poor Soil Structure

Tillage – Breaking up compacted layers can be done eff ectively when deep tillage equipment 

is operated correctly (See Section 10.1.2, Tillage).

Incorporate Organic Matter – The eff ectiveness of deep tillage can be enhanced if organic 

matter is incorporated into the soil prior to tillage (See Section 10.1.5, Organic Matter 

Figure 5.17 – A simple, qualitative 

method of determining compacted 

layers is to mark the face of a long shovel 

with a ruler. By pushing the shovel in 

the ground with the entire body weight 

and observing the distance the shovel 

penetrated can give a measure of the 

depth to a compacted layer.
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Amendments). Organic matter can keep the soil from settling back to higher, pre-tillage 

densities. Application rates at which organic matter showed positive eff ects on soil structure 

was observed at a ratio of 25% incorporated organic matter to 75% soil by volume (Claassen 

2006). Longer shreds of organic matter are preferred over smaller, chip sizes because the longer 

strands create interconnecting pathways for water, air, and roots while increasing soil strength 

(Claassen 2006). The additions of non-composted organic matter, however, will tie-up nitrogen 

for a period of time. While this might be problematic in the short term, the importance of 

developing soil structure for long-term site recovery might override the concerns about the 

lack of immediately available nitrogen.

Operate Equipment With Care – Soil compaction is greatest when soils are moist. When heavy 

equipment is being used on non-compacted soils, the moisture status of the soil must be 

considered. Under moist and wet conditions, soil structure may be severely damaged. If heavy 

equipment must be used, schedule it during times when the soil is dry. Compaction can be 

also be minimized by using smaller equipment (Amaranthus and Steinfeld 1997). Leaving slash 

or deep mulch on the soil surface can further reduce the amount of compaction because this 

material will provide some cushioning to the soil.

Avoid Last Minute Compaction – There is no avoiding soil compaction during construction, 

but compacting the soil after mitigating treatments have been implemented must be avoided. 

There are many cases where the benefi ts of mitigating treatments have been nullifi ed by the 

lack of attention to heavy equipment operations after topsoil additions or tillage treatments 

have been made. For example, topsoil salvage and placement, as discussed repeatedly in this 

manual, benefi t the site in many ways. But this expensive mitigating measure loses much of its 

value if the soils are compacted during or after soil placement. Once topsoil is deep-tilled, there 

must be no more passes by equipment over the soil.

5.3.4 Rooting Depth

Rooting depth is the distance from the surface of the soil to the lower reaches that roots can 

penetrate. It encompasses any strata that can be accessed by plant roots (topsoil, subsoil, and 

parent material). The deeper the rooting depth of a disturbed site, the greater the total available 

water storage and the higher the productivity of the site.

Rooting depth is aff ected by restrictive layers that block root penetration to lower strata 

(See Section 5.7.2, Restrictive Layer). For example, the rooting depth of a post construction 

site is estimated at 6 feet deep. However, further investigation fi nds that there is a highly 

compacted layer at 12 inches, which would limit most, if not all, root penetration below that 

point. The rooting depth under these conditions has been reduced to only one foot of soil 

instead of six feet. Restrictive layers also include soils with very high or low pH, toxic materials, 

or a high water table.

Rooting depths vary by plant species and age of the vegetation. Most mature tree species 

have deep root systems that access subsoil and parent material; roots of grasses and forbs are 

predominantly limited to the surface soils. Annual grasses and forbs require less rooting depth 

than perennial grasses and forbs, with the roots of these species growing in the upper surfaces 

of the soil. The age of the vegetation also determines the abundance and location of roots. 

Newly established seedlings have shallow roots but, as the plants mature, root systems expand 

to access moisture deeper in the soil.

Rooting patterns and root morphology play a role in how plants access soil water. Some species 

have fi ner textured root systems that access tightly held soil moisture; other species have 

aggressive root systems that can penetrate deeply into cracks between rock fragments. 

Grasses, for instance, have shallower root systems than trees and shrubs, but their small size 

and high density in the surface soil gives them an advantage in shallow soils.

5.3.4.1 Rooting Depth – How to Assess

Rooting depth should be estimated from reference sites during planning and post-construction, 

but is not always an easy parameter to measure. Observing road cuts is often the best means 

to determine rooting depth below the topsoil and subsoil. Rock type (e.g., granite, sandstone, 

schist), fracturing patterns, rock weathering, and the degree of rock fracturing will give an 

indication of rooting depth. Observing the amount and type of roots in the fractures of existing 

road cuts will give a good idea of rooting depth.
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Fracturing and weathering of rock can also be determined from geotechnical analysis. If the 

bedrock has been drilled, the drill log report can give an indication of degree and depth of 

rock fracturing and weathering. One way that rock quality is assessed is through a classifi cation 

called the Rock Quality Designation Index (RQD). This system rates the bedrock by how much 

fracturing is observed in the cores. It is calculated by measuring the pieces of rock in the core 

sample that are longer than 10 cm, summing the length of these pieces, and dividing by the 

total length of the core (Deere and Deere 1988). A small RQD means that the bedrock is highly 

fractured whereas a high RQD means the bedrock is massive. A RQD may be poor from an 

engineering standpoint because of the high fractures, but favorable from a revegetation 

standpoint because cracks will hold some moisture and allow root penetration. A RQD rated as 

“very poor,” “poor,” and even “fair” should be somewhat favorable to root penetration.

Rooting depth is also aff ected by the presence of a restrictive layer caused either naturally or 

by compaction. How to determine the presence of these layers is addressed in Section 5.3.3.1 

and Section 5.7.2.1.

There are many references in the literature defi ning the depth of soil needed to support 

diff erent plant communities. For example, 18 inches of soil has been shown to support simple 

grassland ecosystems, but more diverse native grassland communities are reported to require 

up to 4 feet or more (Munshower 1994). These fi gures can be misleading if they are not put in 

the context of site climate and soil type. In many respects, it is more useful to state the total 

available water-holding capacity (TAWHC) of a site rather than the rooting depth. 

Figure 5.18 shows how the TAWHC is calculated. Using the same format and equations, a 

similar spreadsheet can be created for your use by copying the equations into the “Results” 

column. In this example, there is 1 foot of topsoil and 2 feet of subsoil over a highly fractured 

basalt. The topsoil has a loam texture and available water-holding capacity of 2.0 inches 

(estimated from Figure 5.11 or obtained from lab results) but, because of the rock fragments, it 

is reduced by approximately 0.4 inches. The subsoil has a high water-holding capacity because 

of high clay content, but the available water-holding capacity is reduced by half due to rock. 

Highly fractured basalt is encountered at a depth of 2 feet, and it is estimated from the road 

cut that approximately 30% is actually fractured. Within these weathered fractures is a gravelly 

clay loam textured material storing approximately 0.5 inches of water. The TAWHC for this site 

would be the sum of all sections of soil (approximately 3.2 inches).

The TAWHC can be used for relative comparisons between revegetation units and reference 

sites. For example, the TAWHC for a post construction soil is 3.6 inches compared to an adjacent 

reference site, which is 6 inches. If the desired future condition of the post construction soil is 

to be similar to the adjacent reference site, then the TAWHC of 3.6 inches must be increased 

upward toward 6 inches for the site to be capable of supporting the vegetative community 

occurring on the reference site.

5.3.4.2 Mitigating for Poor Rooting Depth

Increase Available Water-Holding Capacity – Improving the water-holding capacity of the 

existing soil will increase TAWHC. Mitigating measures discussed in Section 5.3.1, Soil Texture 

and Section 5.3.2, Rock Fragments can be used to increase soil moisture.

Tillage – If restrictive layers due to compaction are encountered, deep tillage should be 

considered. Section 10.1.2 provides guidelines for deep tillage. 

Apply Topsoil – Increasing rooting depth and TAWHC can be accomplished by applying topsoil 

(See Section 10.1.4).

Planting Islands – Mitigating measures, such as applying topsoil, organic matter incorporation, 

deep tillage, and other measures that increase water-holding capacity, can be focused in 

strategic locations, such as planting islands. This will conserve on materials and reduce costs 

(See Section 10.1.8.4).

Blasting – Strategic blasting to shatter the parent material has been suggested (Claassen 2006) 

as a possible means of increasing rooting depth.
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0 to 1'

Soil

Strata Data Soil Characteristics Results Equations

AWHC of texture (inches / foot): 2 2

0.264

0.1

1

1.6

(A) From Figure 5.11 or lab results

(B) = A * (B / 100) * 0.66

= A * (C / 100)

(the thickness of soil section)

= (A - B - C) * D

From Figure 5.11 or lab results

= F * (G / 100) * 0.66

= F * (H / 100)

(the thickness of soil section)

= (F - G - H) * I

From Figure 5.11 or lab results

= K * (L / 100) * 0.66

= K * (M / 100)

(the thickness of soil section)

= (K - L - M) * N

(C)

(D)

(F)

(G)

(H)

(I)

(K)

(L)

(M)

(N)

(E)

(J)

(O)

20

5

1

Small Rock (%):

Large Rock (%):

Thickness (ft):

Available water by section:

AWHC of texture (inches / foot): 2.2 2.2

0.5082

0.55

1.1

35

25

1 1

Small Rock (%)

Large Rock (%):

Thickness (ft):

Available water by section:

AWHC of texture (inches / foot): 2.2 2.2

0.5082

1.54

0.5

35

70

3 3

Small Rock (%)

Large Rock (%):

Thickness (ft):

Available water by section:

1 to 2'

2 to 5'

Total Available Water Holding Capacity (inches): 3.2 = Sum of (E, J, O)

Figure 5.18 – The total available water-holding capacity (TAWHC) is the total amount of 

moisture that a soil can store for plant growth when fully charged with water. TAWHC values 

for each revegetation unit are helpful for determining which species will perform well, and in 

developing the mitigating measures necessary to increase water-holding capacity or rooting 

depth. TAWHC is calculated by determining the texture, rock fragment content, and depth of 

each soil layer, and calculating how much water each layer will optimally store. The waterholding capacity of each soil layer is added together to obtain the TAWHC for the soil profi le. 

The analysis requires determination of rooting depth to ensure that deep moisture is taken 

into account.

61

5.3.5 Mycorrhizal Fungi

The discussion to this point has addressed the primary factors responsible for soil water storage 

(soil texture, rock, and rooting depth) and the accessibility of roots to grow to this water (soil 

structure). In this section, the discussion turns to how plants increase the effi ciency of accessing 

water through mycorrhizae. While mycorrhizae provide many other benefi ts to the site besides 

water enhancement, they are covered in depth in this section because of the importance of 

water to establishing vegetation on highly disturbed sites in the western United States.

Mycorrhiza is the unique symbiotic relationship between fungi (called mycorrhizal fungi) and 

host plants. To the naked eye, many mycorrhizal fungi appear as a fi ne web or netting that seems 

to connect the root system to the surrounding soil (Figure 5.19), and in essence, this is exactly 

what is occurring. The extremely small hyphae of the mycorrhizal fungi are actually taking on 

the form and function of an extended root system of the plant. Because mycorrhizal hyphae 

are up to fi ve times smaller than plant roots, they are able to access spaces in the soil not easily 

accessible by the larger plant roots. Mycorrhizal hyphae not only provide the plant with a greater 

access to soil moisture and nutrients, they also surround and protect roots from soil pathogens. 

In return, the host plant supplies carbohydrates to keep the mycorrhizal fungi alive.

Mycorrhizae play a critical role in site restoration by building soil structure. Hyphae and water 

stable organic “glues,” like glomalin, are excreted by the mycorrhizal fungi and bind soil particles 

together into aggregates. These aggregates stabilize the soil, improving soil structure (See 

Section 5.3.3, Soil Structure) important for good air exchange and water permeability. This basic 

soil building process, or repair, facilitates the creation of nutrient reserves and nutrient cycling 

essential for restoring ecosystems (Miller and Jastrow 1992). Mycorrhizal fungi can also improve 

survival of tree and grass seedlings (Steinfeld and others 2003; Amaranthus and Steinfeld 2005). 

A healthy population of mycorrhizal fungi has also been shown to increase plant biomass and 

cover (Wilson and others 1991; Brejda and others 1993; Sobek and others 2000), and increase 

the diversity of native species (Smith and others 1998; Charvat and others 2000).
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Ninety percent of all terrestrial plants form symbiotic relationships with mycorrhizal fungi. Of 

the thousands of known species, most generally fall into two categories – ectomycorrhizal 

fungi and arbuscular mycorrhiza fungi.

Arbuscular mycorrhizal fungi (AMF), formerly called endomycorrhizae, are the most commonly 

occurring mycorrhizal fungi, forming on 75% to 85% of plant species. These include legumes, 

composites, grasses, bulbs, most shrubs, and ferns. In addition, AMF occur on many tree species, 

including redwoods and some cedars, and many types of tropical trees. AMF grow inside the 

roots of the host plant and extend hyphae out into the soil. These fungi are more general 

in their association with plant species, meaning that one mycorrhizal species can form an 

association with a broad spectrum of plant species. AMF reproduce in two ways: 1) by forming 

single spores outside of the root, and 2) from fungal structures (vesicles and hyphae) present 

inside a colonized root system. Arbuscular mycorrhizal fungi do not disperse their spores in the 

wind, but instead are dispersed from root to root or by animals. For this reason, recolonization 

of drastically disturbed sites by arbuscular mycorrhizal fungi can be slow, especially if there are 

limited sources of healthy, undisturbed soils nearby to repopulate the site.

Unlike arbuscular mycorrhiza fungi, ectomycorrhizal fungi, as the name implies, coat the 

outside of the roots with hyphae that extend out into the soil. Ectomycorrhizal fungi form on 

5% to 10% of plant species, the majority of which are forest trees in the western United States. 

Species include Douglas-fi r, western larch, true fi rs, spruce, hemlock, oak, manzanita, willows, 

and cottonwood. These fungi form a netting of fi ne hyphae around the root system of the tree 

that is often observable on nursery produced seedlings inoculated with mycorrhizal spores. 

Unlike AMF, the relationship between ectomycorrhizal fungi and host species is very specifi c. 

Many ectomycorrhizal fungi species have evolved to associate with only one plant species. 

Ectomycorrhizal fungi produce fruiting bodies, such as mushrooms, puff balls, and truffl es, that 

yield reproductive spores for wind or animal dispersal.

AMF and ectomycorrhizae do not associate with all plant species found in the western United 

States. Manzanita and madrone, for instance, form arbutoid mycorrhizae, while huckleberry 

form ericoid mycorrhizae. The remaining 10 % of plant species do not form mycorrhizae at all. 

Many of these plant species have evolved root systems that function similarly to mycorrhizae 

and therefore can outcompete mycorrhizal species during early establishment on highly 

disturbed sites. While host plants might be present during early establishment of these sites, 

they nevertheless languish because of the lack of mycorrhizal fungi, giving non-mycorrhizal 

species a distinct advantage. This advantage is why many plant species that are considered 

weeds are non-mycorrhizal species.

5.3.5.1 Mycorrhizal Fungi – How to Assess

Where soils have been drastically disturbed, it can be assumed that the mycorrhizal fungal 

propagules that colonize plant roots are drastically reduced or absent from the site. The size 

Figure 5.19 – Mycorrhizal fungi can 

greatly increase the surface area of 

the root system. The ectomycorrhizal 

fungi attached to the pine root system 

(A) comprise most of the absorptive 

surface shown in this photograph. The 

mycorrhizae include brown branched 

structures (B) and white hyphae or 

fi laments (C). (Photo courtesy of Mike 

Amaranthus, Mycorrhizal Applications).
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and severity of the disturbance determines the colonization rates of mycorrhizal fungi. As the 

level of disturbance increases, the density of viable fungi propagules typically decreases. Small 

disturbances surrounded by native forests or rangelands often reestablish quickly; in larger 

disturbances, where topsoil has been removed, recolonization by mycorrhizal fungi may 

take years.

Some laboratories off er testing for mycorrhiza fungi, but these are expensive tests. Since 

it is unlikely that mycorrhizal fungi will be found in recently disturbed sites lacking topsoil, 

conducting these tests for most projects are unnecessary.

5.3.5.2 Mitigating for Lack of Mycorrhizal Fungi

For most construction projects, the management of mycorrhizae should be considered 

in the early stages of project planning. Several strategies are available to enhance 

mycorrhizal colonization.

Minimize Soil Disturbance – Operations that maintain topsoil will often preserve mycorrhizal 

inoculum and maintain soil nutrition. Partially disturbed topsoil is often adequate for 

reestablishing mycorrhizal plant species. Partial disturbances include clearing and grubbing 

of road right-of-way vegetation, ground-based logging, and light to moderate intensity 

burns. Colonized root systems left behind in these operations are sources of inoculum 

for endomycorrhizae.

Leave Undisturbed Areas – The colonization of AMF into highly disturbed sites is slow. Spores 

are transported by soil erosion and animal movement, but not by air. By leaving small areas of 

native vegetation and undisturbed soils within the larger disturbance, travel distance for the 

spread of fungi is reduced, facilitating a quicker repopulation of AMF. This practice is especially 

important where the size of the disturbance is large.

Salvage Topsoil – Reapplying topsoil to drastically disturbed sites is commonly done when 

quality native topsoil is available (See Section 10.1.4, Topsoil). If topsoil is obtained from nonforested sites, such as meadows, rangelands, and unforested clearcuts, AMF is often abundant 

because the host plants are grasses and forbs. It should not be assumed, however, that there 

will be ectomycorrhizal spores present to colonize the roots of tree seedlings.

Figure 5.20 – The response to the addition of mycorrhizae spores to non-inoculated seedlings 

can sometimes be dramatic. Both sets of sticky currant (Ribes viscosissimum) seedlings shown 

in this photograph were stunted for months after seed germination. AMF spores were applied to 

the surface of each seedling container on the left with immediate growth response, while those 

on the right remained stressed (photo taken 50 days after inoculation).
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10

9

8

7

6

5

4

3

2

1

0

Inches

10

9

8

7

6

5

4

3

2

1

0

Inches

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Months Months

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Evapotranspiration

Precipitation

Moisture De cit

Germination

Portland, OR Bend, OR

Figure 5.21 – Evapotranspiration (ET) rates can be found for many climate stations at 

http://www.wrcc.dri.edu. Plotting monthly evapotranspiration rates with precipitation rates 

(also found at this website) gives a good indication of the climate during plant establishment 

and growth phases. The following graphs show that the climate in Portland, OR has a very 

favorable environment (low ET and high precipitation) for seed germination in March; plant 

establishment should be adequate without the need for extra mitigating measures. The weather 

in the fall is also conducive to germination and plant establishment. The climate at Bend, OR 

during April and May, when seeds in that area germinate, has very high ET rates and very low 

rainfall; mitigating measures such as applying mulch over the seeds at sowing might be critical 

for success.

64

Apply Topsoil to Planting Holes – If topsoil is very limiting, placing healthy topsoil into holes 

prior to planting seedlings is an eff ective method of introducing an inoculum to a disturbed 

site. Collecting soils as inoculum from young, actively growing forests has been shown to be 

suitable inoculum for young tree seedlings (Amaranthus and Perry 1987).

Apply Commercially Available Mycorrhizal Fungi Inoculums – Applying commercially 

available mycorrhizal fungi inoculum is another method used to repopulate highly disturbed 

sites (See Section 10.1.7, Benefi cial Soil Microorganisms). Commercially available sources of 

mycorrhizal inoculums are available for ectomycorrhizal and AMF plant species. These inoculums 

can be applied in hydroseeding slurries, as seed coats and root dips, through irrigation systems, 

or incorporated into the soil by broadcasting or banding. When purchasing live plants from 

a nursery, rooting media can be inoculated with mycorrhizal fungi during nursery culture 

(Figure 5.20). Fine grades of mycorrhizal inoculum can be applied to the surface of the soil and 

will move into the soil surface with rainfall. Coarser textured commercial inoculums must be 

incorporated in the soil to make them eff ective.

Reduce Fertilizer Use – While the application of fertilizer can increase plant biomass in the 

short term, it can also suppress mycorrhizal infection (Jaspers and others 1979; Claassen and 

Zasoski 1994). However, low rates of fertilizer have been shown to help establish plant cover 

and improve mycorrhizal colonization (Claassen and Zasoski 1994).

5.4 WATER LOSS

Water loss is the depletion of soil moisture during the year through transpiration (loss of water 

through leaves/needles) and evaporation of soil moisture from the soil surface. The rate at which 

evaporation and transpiration draw moisture from the soil profi le is the evapotranspiration (ET) 

rate. ET rates can change daily, weekly, and seasonally: 1) daily changes occur as the sun hits 

vegetation, temperatures and wind speeds rise, and ET rates increase; 2) weekly changes occur 

when ET rates rise and fall as weather systems change from hot and dry to cool and wet; and 

3) seasonal changes occur as air temperatures rise in spring, reaching maximum temperatures 

and minimum humidities in the middle of the summer, then decline in the fall (Figure 5.21).

Water loss due to ET can be infl uenced by a number of abiotic and biotic factors, primarily:

 · Wind,

 · Site aspect,

 · Competing vegetation, and

 · Soil cover.
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Soil Moisture

Months

Relative Moisture

A

ET PMS Low

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Figure 5.22 – High Conceptual 

relationship between 

evapotranspiration (ET), soil 

moisture, and plant moisture stress 

(PMS). PMS lags behind ET in late 

spring because soil moisture is 

still moderate to high from the 

winter rains. By mid summer (A), 

plant moisture stress has increased 

to its greatest level in the year 

because soil moisture is at its 

lowest. Newly planted seedlings 

undergo extreme stress during this 

period. Unless their root systems 

have grown deeper into the soil, 

accessing a greater soil moisture, 

or ET rates are reduced by cooler 

weather, seedlings will die. In late 

summer and early fall, cooler 

weather returns and rains wet 

the soil, driving ET and PMS rates 

down again.

Location Water Potential

(MPa)

Soil (A)

Plant Roots (B)

Plant Stem (C)

Plant Leaf (D)

Plant Stomata (E)

Atmosphere (F)

- 0.1

- 0.3

- 0.6

- 0.9

- 25.0

- 125.0

A

B

C

D

E

F

Figure 5.23 – Plant moisture stress 

(PMS) is a measure of the tension or pull 

of moisture through a vascular plant. 

Much like a straw, when the demand for 

moisture at the surface of leaves is high, 

moisture is drawn from the stomata. 

This creates a pull of water through the 

leaves, stem, and down to the roots, 

which draws water from the soil.

65

On both disturbed and undisturbed sites, the eff ects of wind patterns and aspect on ET rates 

infl uence the types of species that can survive and grow. Competing vegetation that colonize 

a site following disturbances can have a large infl uence on the amount of soil moisture stored 

and the availability to desirable plants.

Evaporation of moisture from the soil surface is not generally a major factor on undisturbed 

soils because they are often protected by a surface mulch of litter and duff . These soil 

covers allow rainfall or snowmelt into the soil, but create a barrier to surface evaporation. 

Surface evaporation becomes a factor when these protective covers are removed or destroyed 

during construction.

Consider the plant as the “middleperson” between the atmosphere, which demands water from 

the plant, and the soil, which acts as a bank of moisture from which the plant is able to draw. 

When the atmosphere is demanding very little water (low ET rate), the plant easily pulls water 

from the soil to the leaves. Over time, as soil moisture becomes depleted, the plant comes 

under greater stress. Not only is the atmosphere demanding greater moisture from the plant, 

but less moisture is available. Consequently, the plant comes under very high moisture stress. 

The amount of stress that a plant is under is referred to as plant moisture stress or PMS (Figure 

5.23). PMS is at its highest from middle through late summer in the western United States, when 

the ET rates are at their highest and soil moisture levels at their lowest.

5.4.1 Wind

Wind is often overlooked as a factor in the success or failure of reestablishing native vegetation, 

but it can play a major role, especially on sites where summers are hot and dry and soil moisture 
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levels are low. Until seedlings become established, high winds can severely limit growth and 

can ultimately lead to mortality.

5.4.1.1 Wind – How to Assess

Wind speed equipment is available, but most likely too costly for most revegetation specialists. 

Site visits during diff erent times of the year can give some indication whether wind is a problem. 

Other site characteristics, such as position on the slope (e.g., ridgelines are more prone than 

valley fl oor), or proximity to forested environments – as forests often reduce wind speeds, – can 

be used to infer wind strengths and directions. In many environments, prevailing winds often 

come from one, or sometimes two, directions. Existing vegetation can sometimes give clues to 

prevailing wind directions (e.g., trees bent away from the prevailing wind). County and state 

department of transportation employees are often resources for local weather information. 

Recognize that road construction itself may change wind patterns (e.g., creating a wind 

tunnel by constructing a throughcut or removing a swath of existing vegetation). Some visual 

indicators of wind erosion are wind scour (See Figure 5.40 in Section 5.6), exposed roots, and 

deposition areas.

5.4.1.2 Mitigating for High Wind

Road Design – Designing islands of undisturbed vegetation to help break up wind patterns 

can aid vegetation establishment. The taller the plants left undisturbed, the greater the wind 

protection. Established trees, particularly those with low-growing branches, give the greatest 

protection from wind. 

Wind Barriers – Obstacles that block wind at the soil surface can be eff ective for early seedling 

survival. These obstacles can include stabilized logs, large rocks, berms, and stumps. In using 

these structures, seedlings should be planted on the windward side.

Tree Shelters – Tree shelters completely surround seedlings and block them from the wind (See 

Section 10.4.4, Tree Shelters). They are an eff ective means of reducing ET rates created by high 

winds during early establishment. Once the vegetation has emerged from the top of the tube, 

however, tree shelters no longer protect the emerging foliage from the wind. 

Shade Cards – Shade cards are sometimes used to block wind, but they are less eff ective than 

the fully enclosed tree shelter (See Section 10.4.3, Shade Cards). When used to block wind, 

shade cards must be placed on the windward side of the seedling, which is not necessarily the 

same location that cards would be placed if protection from sun is the objective. Often two 

shade cards are placed around the seedling for added protection against the wind. Placement 

of the shade cards at the height of the foliage aff ords greater protection to the seedling.

Appropriate Species Selection – The drying and damaging eff ects of wind are important 

considerations in appropriate species selection. A simple assessment of soil type and rainfall 

may not account for the eff ects of wind. Choosing hardier, wind-tolerant, and more droughttolerant species may be necessary to establish vegetation on windswept sites. Find reference 

sites in windy locations to indicate which species are adapted to wind.

Leave Surface Roughened – A roughened soil surface can create a micro-basin or relief that 

protects young germinants from the drying eff ects of wind during the establishment phase 

(See Section 10.1.2, Tillage).

5.4.2 Aspect

Aspect is the direction a slope is facing, and is one of the predominant site characteristics 

aff ecting evapotranspiration. South and west aspects receive more solar radiation during 

the day and have higher ET rates than north and east slopes, and are therefore warmer and 

drier. Soils on these sites dry out faster than north and east slopes. In spring, during seed 

germination, south and west aspects can dry very quickly between rainstorms, reducing the 

rates of germinating seeds. As seedlings emerge and grow through spring and early summer, 

temperatures on the south and west slopes continue to rise to very high levels, creating very 

unfavorable conditions for seedling establishment. Even with planted seedlings, high surface 

temperatures can damage stems near the ground line, severely aff ecting seedling survival and 

establishment (Helgerson and others 1992). 
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Warm

Cold

Cool

Cool

NW

West East

North

October – March

South

NE

SW SE

Cool

Hot

Warm

Warm

NW

West East

North

April – September

South

NE

SW SE

Figure 5.24 – Site climate changes throughout the year depending on aspect.

67

In moist, cool climates, where moisture is not the limiting factor, south and west slopes are 

often very productive and have greater cover. Warmer soil and air temperatures create a longer 

growing season, off setting the eff ects of moisture stress on plant growth. 

On high elevation sites, north and east aspects are cold compared to the south and west 

aspects. The growing season is much shorter, resulting in very diff erent composition of species 

between aspects. At high elevations, soil temperatures on south and west slopes stay higher 

longer in the fall, providing the opportunity to plant in the late summer and early fall months 

(Figure 5.24). During the spring at all elevations, south and west slopes warm up much sooner 

than north slopes. The diff erences in soil temperatures between north and south aspects is a 

consideration for determining when to plant.

5.4.2.1 Aspect – How to Assess

Aspect is measured in the fi eld by facing the fall line of the slope (the imaginary line a ball 

would roll) and taking a compass bearing downslope. A “northeast slope,” “northeast aspect,” 

“northeast exposure,” or “northeast-facing slope” all refer to an aspect with a compass bearing 

facing northeast. 

Aspect can also be measured from topographic maps by drawing an arrow perpendicular to 

the contour lines and pointing the tip of the arrow downslope. Aspect is often a factor for 

delineating one revegetation unit from another due to the strong infl uence on growth and 

survival of seeds, seedlings, and cuttings. It can be useful to diff erentiate revegetation units 

using aspect by highlighting all areas on the road plan map with south to west slopes.

Soil and air temperatures diff er greatly between aspects; taking temperature measurements 

can be important for assessing the eff ects of aspect on revegetation. There are many types 

of recording devices available on the market, but only equipment that can download data to 

spreadsheets for analysis and graphing should be considered. Some equipment has become so 

inexpensive that more than one unit can be purchased (Figure 5.25).

5.4.2.2 Mitigating for South and West Aspects

For most sites, any treatment that will shade vegetation on the south and west slopes from 

intense solar radiation should increase survival and growth of establishing plants.

Overstory Vegetation – Keeping overstory trees at a minimum density of one tree per tenth 

acre is a rule of thumb for reducing soil temperatures below lethal levels on south aspects 

(Helgerson and others 1992).

Shade Cards – Shade cards can signifi cantly increase seedling survival on south aspects 

(Hobbs 1982; Flint and Childs 1984) (See Section 10.4.3, Shade Cards). They must be placed 

close to planted seedlings so that the stem and lower portion of the seedlings are shaded from 

the afternoon sun (Helgerson and others 1992).

Obstacles – Large obstacles that cast signifi cant amounts of shade on young seedlings will 

create a more favorable environment for seedling establishment and increase seedling survival 
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(Minore 1971). These include stabilized logs, large rocks, berms, and stumps. Seedlings should 

be planted on the north and east side of these features to be shaded from the afternoon sun.

Mulch – On south exposures, the use of mulches as a moisture barrier should be considered for 

seedlings, seeds, and cuttings (See Section 10.1.3, Mulches).

Species Mix – The composition of species will probably be diff erent for north and south aspects. 

Species adapted to hotter and drier environments are used for revegetating south exposures; 

those adapted to cool, moist environments are used on north aspects. Elevation can off set 

the eff ects of aspect. For example, species that grow on low elevation, north aspects often 

occur several thousand feet higher on south aspects because of the diff erence in temperatures. 

Reference site vegetation surveys will guide the revegetation specialists in the selection of 

appropriate species for each exposure.

Plant Material Rates – South aspects often require a higher density of seedlings, cuttings, and 

seeds than north aspects due to the expected higher mortality rates. Adjusting for increased 

mortality rates is made when calculating plant materials rate for seeds (See Section 10.3.1), 

cuttings (See Section 10.2.2.5), and plants (See Section 10.2.5).

Planting and Sowing Windows – Take advantage of warmer spring and fall soil temperatures 

on the south exposures by sowing and planting earlier on these sites (See Chapter 6).

5.4.3 Competing Vegetation

Controlling competing vegetation, whether native or non-native, around planted seedlings 

reduces the rate at which water is withdrawn from the root zone and increases the potential for 

survival and growth. A major factor aff ecting seedling survival and growth is the timing and 

the extent to which roots of competing vegetation encroach into the soil around the roots of 

the planted seedling. Annual grasses and forbs generally germinate early in the season as soil 

temperatures warm, often before native species. The early establishment of annual grasses 

and forbs deplete surface soil moisture, making it harder for perennial species to become 

established. Cheatgrass is an example of an annual species that establishes quickly in the early 

spring and depletes the soil moisture in the spring as perennial species are just beginning 

to germinate.

The rate at which water is depleted is a function of the type of competing species. Grass species, 

for instance, have very fi brous root systems in the surface soils which allow them to withdraw 

moisture very quickly and effi ciently during dry weather. Unless grasses are controlled, it is 

very diffi cult to achieve good survival of planted seedlings in areas with high densities of grass. 

Perennial forbs are generally less competitive than grasses because their root systems are 

deeper and less concentrated in the surface where the seedlings are withdrawing moisture.

5.4.3.1 Competing Vegetation – How to Assess

Predicting the potential for vegetative competition at the time of planting on highly disturbed 

sites is diffi cult at best. If disturbed sites have been included as reference areas, some predictions 

of competing vegetation can be made. If competing vegetation becomes established, methods 

described in Chapter 12 for measuring ground cover can be used for assessment.

Figure 5.25 – Temperature recording 

technology has become smaller and very 

inexpensive. The iButton® shown next to 

the nickel can record more than a year of 

temperature data.
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Air Rainfall Evaporation

Figure 5.26 – An eff ective mulch for 

seed cover is one that is stable and 

allows good airfl ow and rainfall entry, 

while reducing evaporation from the 

soil surface.

69

5.4.3.2 Mitigating for Competing Vegetation

Do Not Wait to Revegetate – Competing vegetation increases over time. The fi rst year 

after construction is the optimum period to establish vegetation from seeds, seedlings, or 

cuttings. By the second or third years, competing vegetation is likely to dominate the site if no 

revegetation treatments have been applied. If competing vegetation dominates the site before 

native plants have become established, the measures to control the competing vegetation 

become far more expensive and less eff ective.

Scalping – Removal of competing vegetation by manually scraping or scalping the soil surface 

to remove weeds is ineff ective in increasing seedling survival on dry sites when the area scalped 

is small (<2 foot radius); scalping becomes eff ective when the clearing is very large (2 foot 

radius or greater). Some of the problems associated with scalping are: 1) topsoil is removed; 

2) surface soil evaporation is high; 3) weeds can invade on the bare soil; 4) infi ltration rates are 

low; and 5) soils are prone to erosion. Scalping becomes more eff ective when the treated soils 

are immediately covered with a mulch or weed barrier cloth.

Mulches – Mulches have been shown to increase survival and growth of newly planted 

seedlings by reducing the amount of moisture loss through evaporation and plant competition 

(DeByle 1969; Lowenstein and Ptikin 1970; Davies 1988a, 1988b; Helgerson and others 1992). 

There is an array of mulches that can be used around seedlings (See Section 10.1.3, Mulches).

Herbicides – The use of herbicides for controlling competing vegetation around seedlings 

has been shown to be eff ective in increasing survival (Childs and Flint 1987). Not only is soil 

moisture increased in the rooting area of the planted seedling due to reduced transpiration, 

but dead foliage acts as a mulch or shade, further protecting the soil from moisture loss. There 

is a risk in using herbicides around shrub or tree seedlings because most herbicides are toxic to 

these species. The result of using herbicides may range from lower growth rates in subsequent 

years to increased mortality in the desirable species. This risk can be reduced by 1) using soilactive herbicides, 2) using extreme care when applying herbicides, 3) utilizing herbicides low 

in toxicity to the planted species, and 4) applying them during periods when the seedlings 

are less susceptible to damage (Helgerson and others 1992). If the road is on public lands, 

the land managing agencies should be contacted to discuss policies regarding the use of 

herbicides. Herbicides must only be applied by a trained professional following manufacturer 

and government guidelines and regulations for safe application and use.

5.4.4 Soil Cover

The thickness and composition of material that covers the soil surface infl uences many 

important soil properties covered in this manual, such as infi ltration rates, interception losses, 

soil temperatures, surface erosion, runoff , and soil moisture loss. The following discussion will 

focus on soil cover as it aff ects soil moisture loss through evaporation.

Under undisturbed conditions, soil cover is predominantly composed of duff , litter, and stems of 

plants. Duff and litter layers form ideal surface mulches because they allow rainfall or snowmelt 
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into the soil while blocking the escape of soil moisture through evaporation. They are also 

unfavorable seedbeds for weed seeds because duff and litter dry out quickly (Figure 5.26). 

Disturbed soils, on the other hand, are mostly composed of bare soil. Evaporation from the 

surface of bare soil can be high, extending to at least 6 inches below the soil surface, aff ecting 

seed germination and seedling establishment rates. Until roots of establishing seedlings 

have extended further into the soil profi le, surface drying will negatively aff ect seedling 

establishment, especially on sites where water input and storage are already limiting.

5.4.4.1 Soil Cover – How to Assess

Soil cover can be measured on undisturbed and disturbed reference sites or post-construction 

sites through ground cover monitoring protocols outlined in Section 12.2. In this protocol, 

the percentage of area in litter, duff , rock, vegetation, and bare soil is recorded and periodic 

measurements of litter and duff thickness are made. Transects can be conducted after 

disturbances. However, it is likely that where excavation has occurred, there will be no litter, 

duff , or vegetation cover present. 

5.4.4.2 Mitigating for Low Soil Cover

Mulches for Seedlings and Cuttings – Mulches create a more favorable environment for 

establishing seedlings and cuttings not only by reducing surface evaporation, but also 

decreasing the amount of competing vegetation. There are two types of mulches for seedlings 

and cuttings – organic aggregate and sheet mulches. The organic aggregates are thickly 

applied ground wood or bark, while the sheet mulches are made from non-permeable or 

slightly permeable plastic, newspaper, or geotextile. Both types are placed around the base of 

the seedling and cover at least a radius of 1.5 feet from the base of the seedling.

Mulches for Sown Seeds – Selecting and applying mulches over sown seeds diff ers from those 

selected for planted seedlings and cuttings. Mulch application for seedlings and cuttings is 

typically too thick for seeds to germinate and grow through. An ideal seedbed mulch is one that 

is applied at the highest rates without aff ecting seedling emergence. Long-fi bered mulches, 

such as straw, hay, or wood strands, create the greatest loft or thickness but, at lower rates, 

still allow light to penetrate and space for seedlings to emerge. Short-fi bered mulches, such as 

wood fi ber and paper found in hydromulch products, are more compact and create less loft. 

While these products reduce erosion rates, they are not necessarily good as seed covers.

5.5 NUTRIENT CYCLING

Nutrient cycling is the process by which sites store and release essential nutrients for plant 

survival and growth. There are 13 elements, or mineral nutrients. Each fi lls a specifi c role or 

function in plant development and each possesses individual characteristics of movement and 

storage in the soil. This manual will not attempt to explain the role and function of each mineral 

nutrient (there are many good textbooks on this subject). It will instead focus on how nutrients 

cycle through vegetation and soils; how they are captured, stored and released; and what site 

components are essential to support these processes. In contrast to an agricultural system of 

managing optimum growth in crops through fertilization, the goal in wildlands revegetation 

is to create an environment that will support a self-sustaining native plant community that can 

develop through successional processes. This includes facilitating the establishment of nutrient 

cycles in a way that conserves, cycles, and builds nutrients in the system.

Mineral nutrients are stored in: 1) soil, 2) live or dead vegetation, and 3) rock. They are slowly 

released over time at varying rates. The rates at which nutrients are released from each source 

will determine their availability for plant uptake. Rock and fallen trees, for example, both hold 

essential nutrients, but release them to the soil at signifi cantly diff ering rates. The fallen tree 

can take up to 100 years to decompose and release its nutrients; the weathering of rock might 

take over 100,000 years. Soil, on the other hand, can release nutrients in the order of weeks and 

months. Once released, these nutrients are stored, taken up by plants, lost through leaching or 

erosion, or reabsorbed in the soil.

On undisturbed sites, there is a dynamic exchange of nutrients throughout the year. Plants 

absorb nutrients from the soil through the root system and assimilate them into vegetative 

biomass. As plants, or portions of plants, die, they drop leaves, branches, and stems to the 

ground where they eventually decompose and return nutrients to the soil. The nutrients are 

stored in the soil and once again available for plant uptake. This natural process of nutrients 
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moving from soil to vegetation and back again is referred to as nutrient cycling. The factors 

important in nutrient cycling are:

 · Topsoil,

 · Site organic matter,

 · Soil carbon and nitrogen,

 · Nutrients, and

 · Soil pH and salinity.

In a healthy plant community, nutrients are constantly recycled with a minimum amount of 

nutrients lost from the site. On drastically disturbed sites, however, nutrient cycling functions 

poorly, if at all. The topsoil, which holds the greatest concentrations of available nutrients and 

supports the primary microbial activity on the site, is missing or mixed with the subsoil. Organic 

matter, which is a primary source of long-term nutrient supply and energy source, has also 

been removed. Soil nitrogen, the most critical nutrient for plant growth and site revegetation, 

is lacking. Soil nitrogen governs how quickly vegetation will return to a disturbed site and 

how much biomass it will ultimately support (Bloomfi eld and others 1982). Its availability is 

closely regulated by the amount of carbon present in the soil, which is also in fl ux on highly 

disturbed sites.

For many sites that lack topsoil, the subsoil in its place may have pH values that are higher or 

lower than the pH of the original topsoil. pH values at extreme ranges aff ect nutrient cycling 

by making many nutrients insoluble and unavailable for plant uptake. In addition, increased 

soil salinity, which can be caused by soil disturbance and amendments, can disrupt nutrient 

availability and provide unfavorable conditions for plant establishment.

5.5.1 Topsoil

The topsoil is the horizon directly below the litter layer that is characterized by high organic 

matter, abundant roots, healthy microbial activity, good infi ltration rates, high porosity, high 

nutrient content, and high water-holding capacity (Jackson and others 1988; Claassen and 

Zasoski 1998). Most nutrient cycling takes place in the topsoil where the greatest biological 

activity occurs. Decomposing microorganisms fl ourish, feasting on dead vegetation and 

roots and releasing stored nutrients back to the soil. Most life forms occur in forest and range 

topsoils, including mammals, reptiles, amphibians, snails, earthworms, insects, nematodes, 

algae, fungi, viruses, bacteria, actinomycetes, and protozoa (Trappe and Bollen 1981). The top 

6 inches of an acre of forest topsoil can contain as much as a ton of fungi and a half of a ton of 

bacteria and actinomycetes apiece (Bollen 1974). Topsoil depth is highly correlated with the 

nutritional status of the soil and, in Northwest forests, has been found to be highly correlated to 

site productivity (Steinbrenner 1981). Topsoils 

possess humus, which is what gives topsoils 

their dark color. Humus is a stable end product of 

decomposition, important for nutrient storage, 

soil structure, and water-holding capacity.

Sites lacking topsoil have signifi cantly reduced 

productivity, and obtaining even minimal 

revegetation can be very diffi cult. Planted 

seedlings often fail or growth is signifi cantly 

reduced, resulting in inadequate plant cover 

to protect the soils from erosion. Growth of 

planted trees can be reduced by one third to 

one half when planted in subsoil instead of 

topsoil (Youngberg 1981). Restoring these sites 

to functioning plant communities is unlikely 

without mitigating measures.

5.5.1.1 Topsoil – How to Assess

It does not take a soil scientist to determine 

the basic characteristics of topsoil and topsoil 

depth. It is simply a matter of digging holes 

Figure 5.27 – Topsoil is generally 

darker, more friable, and has more roots 

than subsoil.
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175

32

163

125

26

32

137

37

179

117

24

100

90 41

19

Litter and Duff

Roots

Branches and Foliage

Bole and Bark

500

400

300

200

100

0

Nitrogen

Pounds per acre

Phosphorus Potassium Calcium

Figure 5.28 – Most of the nutrients found in a young Douglas-fi r stand reside in the litter, duff , 

and branches (adapted from Cole and Johnson 1981).

1,000

900

800

700

600

500

400

300

200

100

Nitrogen

Pounds per Acre

Phosphorous

Calcium

Potassium

Magnesium 

0

Douglas- r sawdust

Douglas- r bark

Red alder sawdust

Red alder bark

Figure 5.29 – Comparison 

of pounds per acre of 

nutrients resulting from 

bark or wood from 

Douglas-fi r and alder 

trees, based on 2 inches 

of applied organic matter 

(Rose and others 1995).

72

and observing some of the basic topsoil characteristics. Usually topsoil can be diff erentiated 

from subsoil by simple observations. On undisturbed sites, for example, topsoil is visually 

diff erentiated from the underlying subsoil by having darker colors, less clay, better soil structure, 

and higher abundance of fi ne roots. In forest soils, topsoil depths can be more diffi cult to 

diff erentiate from subsoils because the color changes are not always distinct. Other attributes, 

such as the abundance of roots, lack of clays, increased soil structure, and lower bulk density, 

can be used instead. Section 5.11.1, Survey Topsoil, gives a general approach to surveying a site 

for topsoil.

5.5.1.2 Mitigating for Lack of Topsoil

Minimize Soil Disturbance – Where soils are especially fragile and reconstructing topsoil 

conditions is diffi cult, it is especially important to keep the “disturbance footprint” to a 

minimum (Claassen and others 1995). Sites with fragile soils include decomposed granitic soils, 

serpentine soils, and thin, high elevation soils.
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Salvage and Reapply Topsoil – An eff ective practice in revegetating highly disturbed sites is 

salvaging and reapplying topsoils (See Section 10.1.4, Topsoil). This practice has been found to 

greatly increase plant growth and ground cover (Claassen and Zasoski 1994). Topsoil salvage 

and application requires good planning and implementation oversight. In the planning phase, 

a topsoil survey of the planned road corridor will identify the depth for topsoil removal; soil 

testing of the topsoil to be salvaged will indicate the nutrient status (See Section 5.11.1, Survey 

Topsoil). After topsoil is removed and stored, it is reapplied to the disturbed site, ideally at 

depths similar to pre-disturbance reference site topsoils.

Create Manufactured Topsoil – When topsoil is not available, “manufactured topsoil” can be 

created in situ or produced off site and imported (See Section 10.1.4.5, Manufactured Topsoil). 

Manufactured topsoil will lack the native seed bank and some of the biological components 

of topsoil, but it can recreate a rooting zone high in nutrients and organic matter, with good 

water-holding capacity, porosity, and infi ltration.

Create Planting Islands – If sources of manufactured or natural topsoil are scarce or too costly 

for broad scale applications, placing available topsoil in strategic locations, such as planting 

islands, can create a mosaic of productive growing sites.

5.5.2 Site Organic Matter

Site organic matter (OM) consists of plant materials in all stages of decomposition, including 

wood, bark, roots, branches, needles, leaves, duff , litter, and soil organisms. From a nutrient 

cycling standpoint, site organic matter assimilates nutrients drawn from the soil into live 

vegetation. Depending on the type of vegetation and the productivity of the site, the amount 

of nutrients held in organic matter can be signifi cant. Figure 5.28 shows the quantities of four 

major nutrients held in the organic matter of a young Douglas-fi r stand and Figure 5.29 shows 

the quantity of major nutrients found in the application of two inches of material derived from 

Douglas-fi r and alder. These two examples show the possible nutrient reserves that organic 

matter can contribute to a disturbed site if they are used.

While plants are essential in nutrient cycling, equally important are the decomposing 

organisms that release nutrients to the soil. Decomposers consist of thousands of specialized 

species of animals, insects, fungi, bacteria, and actinomycetes that survive on organic matter. 

Decomposing organisms not only release nutrients, but are also essential to the development 

of soil structure (See Section 5.3.3, Soil Structure).

On an undisturbed site, organic matter is in all stages of decomposition, from recently dead 

trees to soil humus, the end product of hundreds of years of decomposition. This understanding 

is important for restoring a site to a 

functioning plant community, since 

it is a reminder that nutrients are 

released throughout the life cycle of 

a plant community, not just at the 

beginning of the revegetation project. 

A site that has a range of organic 

matter in all stages of decomposition 

not only conserves nutrients but 

slowly meters them out over time.

The rate at which organic matter 

decomposes and releases nutrients 

is a function of: 1) soil to OM contact, 

2) OM particle size, 3) carbon-tonitrogen ratio (C:N), 4) temperature, 

and 5) moisture. Decomposition 

rates of organic matter are highest 

in soil because the greatest microbial 

activity occurs when soil is in direct 

contact with OM (Slick and Curtis 

1985; Rose and others 1995). Organic 

matter placed on the surface of the 

soil as a mulch will decompose at a 

Years Decades

Months

Low

High

Particle Size

p

C:N Ratio

Small Large

Years

Figure 5.30 – Relative rates are a function of 

decomposition by C:N and particle size. 

Years Decades

Months

Low

High

Particle Size

Decomposition Rates

C:N Ratio

Small Large

Years

Figure 5.30 – Relative rates are a function of 

decomposition by Carbon to Nitrogen ratio and 

particle size. 
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much slower rate than organic matter incorporated into the soil because there is less contact 

with the soil.

Organic matter particle size plays an important role in the rate of decomposition. Within the 

soil profi le, the smaller-sized OM fractions decompose faster than the larger fractions due to 

greater surface area in contact with soil. Roots, leaves, needles, and very fi nely ground sawdust 

or bark often decompose at a much faster rate than larger materials, such as buried logs or large 

diameter branches. Materials with high carbon to nitrogen ratios (C:N), such as wood or bark, 

decompose at a much slower rate than materials with low C:N, such as green leaves and grass 

cuttings. As Figure 5.30 illustrates, high C:N organic matter will take much longer to decompose 

than low C:N material, but both will decompose faster when they are reduced in size.

Moisture and temperature also control decomposition rates; cold and dry environments have 

very slow rates compared to warm, moist sites.

5.5.2.1 Site Organic Matter – How to Assess

Duff and litter in reference, pre-, and post-disturbance sites can be measured through transects 

or plots (See Chapter 12). Estimating forest biomass of down, woody materials in diff erent size 

classes can be done using photo series guides (Maxwell and Ward 1976a, 1976b, 1979). Fire 

specialists are experienced in estimating the amount of biomass in forested environments.

5.5.2.2 Mitigating for Lack of Site Organic Matter

Salvage and Reapply Litter and Duff – Duff and litter can store a signifi cant amount of 

nutrients, especially on sites where layers are deep. It can be salvaged separately (See 

Section 10.1.3.11, Litter and Duff ) or mixed together when topsoils are salvaged (See Section 

10.1.4, Topsoil).

Chip and Apply Organic Matter – Road projects constructed through forested sites can 

generate high amounts of biomass that must be disposed, usually through burning. 

These materials can be a good source for slow-release nutrients. Methods of chipping and 

reapplication are discussed in Section 10.1.3. Chipped organic matter can be applied directly 

to the soil surface or mixed into the soil. High C:N organic materials, such as sawdust and bark, 

can be placed on the soil surface to prevent long-term nitrogen tieup in the soil, or they can 

be composted for several years to lower the C:N before adding as an amendment. Lower C:N 

materials, such as leaves, needles, and branches, can be placed in the soil with some addition 

of slow-release nitrogen to reduce the eff ects of nitrogen tie-up.

Apply Composts to Soil Surface – Compost functions as a soil cover to protect the soil from 

surface erosion while slowly decomposing and adding nutrients as the plant community 

develops. Decomposition rates of surface-applied compost are slower than mulch incorporated 

into the soil because there is very little soil contact. Nutrients are released at a slower rate and 

are available to the site longer. Leaving the soil surface very rough prior to the application of 

compost creates more soil-to-compost contact, which can increase the rate of decomposition of 

the compost.

Salvage and Place Large Wood – Large wood can be salvaged and placed in areas such as 

abandoned roads for microsite amelioration for revegetation. When placed in contact with the 

Figure 5.31 – Placement of large 

wood adds long-term organic matter 

while creating microsites for planting 

seedlings. Large wood can also slow 

runoff and detain sediments from surface 

soil erosion.
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High C:N Ratio

Time

0

Available N Unavailable N

Low

N

immobilized

Soil

N

C

added

Net increase

in available N

Figure 5.32 – Available nitrogen 

(N) levels change as organic matter 

carbon (C) is added to the soil. 

High ratios move to low ratios 

during decomposition. Nitrogen is 

tied up in microorganisms during 

the immobilization phase (blue 

shaded area) and unavailable 

to plants. With time, nitrogen 

becomes available again and, at 

some point, exceeds the original 

level (green shaded area). Nitrogen 

is then released at a constant rate 

(modifi ed after Havlin and 

others 1999).

75

soil, large wood helps stabilize the surface of the soil from sheet and wind erosion, and can be 

used as buttresses to stabilize slopes. Seedlings planted on the north side of the logs can be 

protected from wind and sun during establishment. Large and small wood can be placed at 

the outlets of culverts as obstacles to capture and store sediments, reducing the amount of 

sediment reaching live streams (Burroughs and King 1989; Ketcheson and Megahan 1996).

5.5.3 Soil Nitrogen and Carbon

Nitrogen (N) is discussed separately from the other mineral nutrients because of its critical 

importance to plant growth and long-term development of plant communities. Carbon (C) is 

included in this discussion because of its unique relationship to nitrogen availability. Carbon 

governs the amount of available nitrogen in the soil while nitrogen regulates the rate at which 

carbon is broken down. Both factors play a critical role in microbiological activity and the 

development of soil properties.

Carbon to Nitrogen Ratio (C:N): Carbon is the energy source for soil microorganisms, and 

practically all site nitrogen eventually passes through these microorganisms (Woodmansee 

1978). The rate at which carbon (or organic matter) decomposes is directly related to the amount 

of available nitrogen and the type of dominant microbes present in the soil. The greater the 

nitrogen, the greater the decomposition rates. If decomposing organisms do not fi nd suffi cient 

nitrogen in the organic matter, they will withdraw it from the soil, leaving little or no nitrogen for 

plant growth. This is usually a temporary condition, lasting several years. The tieup of nitrogen 

can greatly aff ect the establishment of vegetation if organic amendments, such as composts, 

wood chips, or straw, are incorporated into the soil without supplemental nitrogen.

With time, nitrogen is eventually released from the organic matter by microbial activity. 

This nitrogen, plus nitrogen released from dead and decomposing micro-organisms, becomes 

available for plant growth. As organic matter breaks down further, there becomes a net increase 

in available nitrogen. In the last stage of decomposition, microorganisms move to a steady rate of 

decomposition, releasing a constant nitrogen supply. This process can take several years or more 

depending on site factors and organic matter levels. C:N is an indicator of whether nitrogen will 

be limiting or in surplus. A C:N of 30:1 or greater indicates that decomposing organisms have 

consumed the available nitrogen in the soil, leaving little if any available nitrogen for plant growth. 

Plants respond by turning yellow and becoming stunted. A C:N below 18:1 is an indication that 

the decomposing organisms are releasing available nitrogen from the breakdown of organic 

matter at rates that exceed their need, thereby increasing nitrogen for plant uptake (Claassen 

2006). For example, undisturbed topsoils typically have ratios of 10:1 to 12:1, which is suffi ciently 

available for plant growth (Tisdale and Nelson 1975). Dry hay, on the other hand, has a C:N around 

40:1, indicating nitrogen will probably be limiting if the hay is incorporated into the soil.
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Undisturbed

Available Nitrogen Slowly available Nitrogen Unavailable Nitrogen

Drastically

disturbed

Inorganic

fertilizer

Organic

fertilizer

Compost

A

BC D

E

Figure 5.33 – Managing Nitrogen Capital. Undisturbed sites (A) have very high total nitrogen 

levels, with over 95% tied up in organic matter and not available (green). Slowly-available 

nitrogen (blue) makes up 1% to 3% of the total nitrogen; available nitrogen for plant uptake 

(orange) is less than 2% of the total nitrogen. Nitrogen capital is essentially removed on 

drastically disturbed sites (B). The addition of inorganic fertilizer (C) dramatically increases 

available nitrogen, but does little to build nitrogen capital. The application of organic fertilizers 

(D) raises the available and the slowly-available nitrogen, but does not add to the long-term 

reserves. Adding compost to the soil can increase available, slowly-available, and total nitrogen 

reserves (E) to levels comparable to undisturbed soils (A).

76

The use of high C:N materials is often discouraged because of concerns about tying up nitrogen. 

However, there are strategies where the use of high C:N ratio materials can aid the revegetation 

specialist in achieving project goals. One use of high C:N ratio materials can be incorporation 

into the top several inches of soil or application to the surface to intentionally tie up nitrogen. 

The applications would lower the availability of N to annual weedy species, which thrive on 

available nitrogen (See Section 5.8.1.2, Reducing or Eliminating Weed Growing Environments).

Soil Nitrogen Capital: Soil nitrogen capital can be categorized into three nitrogen pools, or 

reserves, based on its availability in the soil:

 · Available nitrogen (referred to as “extractable nitrogen”),

 · Slowly-available nitrogen (referred to as “mineralizable nitrogen”), and

 · Unavailable nitrogen (“humified organic” or “fresh” forms).

Nitrogen capital can be viewed much like our banking system. Cash received from the bank 

teller is comparable to available nitrogen. When the money runs low, the teller replenishes it 

with money from the bank vault (similar to slowly-available nitrogen). Banks are backed up by 

money held in an extremely large banking reserve system, or unavailable nitrogen. While this 

money is not accessible, it is very important for the long-term stability of the banking system. 

Unavailable nitrogen is like the banking reserve system in that it backs up the nitrogen system 

and ultimately releases nitrogen to the plant community.

Like the banking reserve system, having high reserves of both slowly-available and unavailable 

nitrogen assures that available nitrogen levels will be released at constant rates over time, which 

is necessary for the development of a plant community. Figure 5.33 shows the relationship of 

diff erent revegetation treatments on nitrogen capital.

On highly disturbed sites, all nitrogen reserves are low. The course of action in typical 

revegetation projects is to apply inorganic fertilizers during the seeding operation. While this 

immediately makes nitrogen available, it does little for increasing long-term nitrogen reserves. 

Within a year of application, most soils will need more available nitrogen to sustain plant growth. 

Organic fertilizers, on the other hand, provide a combination of available and slowly-available 

nitrogen. These fertilizers release nitrogen over several years, but are typically applied at rates 

not great enough to bring the nitrogen reserves up to levels for long-term plant community 

establishment (Claassen and Hogan 1998). Applying topsoil, composts, or low C:N organic 

matter into the soil are mitigation treatments that create the reserves of unavailable and slowlyavailable nitrogen important for a constant supply of available nitrogen over time.
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Target 

Nitrogen 

Levels

Threshold

De cit

PostConstruction

Soils

Disturbed 

Poor

Revegetation

Disturbed 

Fair

Revegetation

Undisturbed

Subsoil

Undisturbed

Topsoil

3,000

2,500

2,000

Total N (lbs/ac) 1,500

1,000

500

0

Figure 5.34 – Threshold values are determined from reference sites. In this example, the 

threshold was established at 1,100 lb/ac, which was between the total N of a disturbed reference 

site with “poor” revegetation and one with “fair” revegetation. Total N in post-construction soils 

was 650 lb/ac, making these soils defi cient by 450 lb/ac. The undisturbed topsoils of reference 

sites showed a total N of 2,430 lb/ac, which set the target levels of nitrogen between 1,100 and 

2,430 lb/ac.

77

Minimum Soil Nitrogen Levels: Total soil nitrogen is the sum of available, slowly-available, and 

unavailable nitrogen reserves. The level of total soil nitrogen varies by plant community and 

ecoregion. It can range from 20,000 lb/ac in deep forest soils of the Washington and Oregon 

coast (Heilman 1981) to as low as 800 lb/ac in desert grasslands of Southern New Mexico (Reeder 

and Sabey 1987). Shortgrass prairies in the Northeastern Colorado and shrub-steppe prairies of 

the Great Basin have a range of total nitrogen from 4,000 to 5,000 lb/ac (Reeder and Sabey 

1987). Sites that are drastically disturbed often have nitrogen rates below 700 lb/ac. These sites 

cannot fully support vegetative cover. A minimum, or threshold, level of total soil nitrogen 

required for a self-sustaining ecosystem has been suggested at 625 lb/ac (Bradshaw and others 

1982) to 670 lb/ac (Dancer and others 1977) for drastically disturbed sites. But Claassen and 

Hogan (1998) suggest much higher rates might be necessary. In their research on granitic soils 

in the Lake Tahoe area, they found a good relationship between total soil nitrogen and the 

percentage of plant cover. Sites with greater than 40% ground cover contained at least 1,100 lb/

ac total soil nitrogen in the surface foot of soil. This implies that to maintain a minimum of 40% 

plant cover, sites like these must contain at least 1,100 lb/ac of nitrogen, with higher nitrogen 

levels necessary for higher plant cover (See Figure 5.34).

Target levels for available nitrogen released annually from nitrogen sources for plant growth 

range from below 27 to 50 lb/ac (Munshower 1994). These are nitrogen levels that should 

be considered when calculating fertilizer rates (See Section 10.1.1.6, Determine Fertilizer 

Application Rates).

5.5.3.1 Soil Nitrogen and Carbon – How to Assess

Nitrogen Testing – Soil testing for nitrogen should be conducted for: 1) topsoils that will be 

salvaged; 2) reference sites; and 3) post-construction soil materials. Procedures for collecting 

soil samples are presented in Inset 5.2, Soil Testing. The following nitrogen tests are available:

 · Total nitrogen: Total nitrogen is an important test to request; the results will be used 

to determine nitrogen thresholds and nitrogen amendment needs. The common total 

nitrogen tests are Leco and Kjeldahl. Total nitrogen has been found to correlate well 

with plant cover (Claassen and Hogan 1998).
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A. 0.025 % From soil test of post construction soils -

gr/l, ppm, mg/kg, ug/g divide by 10,000 for %

Total soil nitrogen (N)

G. 769 lbs/ac Minimum amount of N to apply to bring up

to threshold

N deficit: F - E =

F. Minimum orthresholdN levels 1,100 lbs/ac Determined from reference sites or literature

E. 331 lbs/ac Calculated amount of total nitrogen in soil layer.

To convert to kg/ha: E * 1.12

N in soil layer: A * B * C * D * 270 = 

D. 70 % 100% minusthe rock fragment content -

from estimates made from sieved soil prior to

sending to lab

Fine soil fraction

C. 1.4 gr/cc Unless known, use 1.5 for compacted subsoils,

1.3 for undisturbed soils, 0.9 for lightsoils

such as pumice

Soil bulk density

B. Thickness ofsoil layer 0.5 feet The thickness of soil represented in (A).

Figure 5.35 – Calculating the nitrogen defi cit of a site – an example.

78

 · Mineralizable nitrogen: This test requires the soil samples to be incubated for a period of 

time and then tested for available nitrogen. The results indicate the amount of slowlyavailable nitrogen present in the sample. It is a very good test to perform because the 

results correlate well with expected plant cover (Claassen and Hogan 1998). There are 

several types of incubation tests, so it is good to confer with the soil laboratory as to 

which tests would be most appropriate.

 · Extractable nitrogen: This test is less meaningful, since it only indicates available nitrogen, 

not what is in reserve. This test is often included in a soil testing package. Extractable N 

pool has the lowest correlation to the amount of plant cover growing on a site (Claassen 

and Hogan 2002). The most common test for extractable nitrogen is 2N KCl extract.

Nitrogen testing for composts and organic matter should be done by laboratories specializing 

in these tests. These laboratories should follow the testing procedures outlined in the Test 

Methods of the Examination of Compost and Composting (TMECC) explained in Section 10.1.3, 

Mulches and Section 10.1.5, Organic Matter Amendments.

Nitrogen Analysis – Soils laboratories report nitrogen in a variety of units, such as gr/l, ppm, 

mg/kg, ug/g, and percent. Unless these values are converted to pounds per acre, it is diffi cult to 

determine rates of fertilizer, compost, or topsoil necessary to restore site nitrogen. Use Figure 

5.35 to convert lab values to total pounds per acre of nitrogen. These calculations account for 

soil bulk density, soil thickness, and coarse fragment content, which aff ect the total nitrogen 

levels of a site.

Nitrogen Thresholds and Defi cits – Each plant community has a total nitrogen requirement 

that must be met in order to develop into functioning and self-sustaining systems. For 

successful revegetation eff orts, a practical goal is to meet the minimum target, or threshold 

level, for total nitrogen. Threshold values, however, are not found in textbooks and must be 

developed from soil tests of disturbed and undisturbed reference sites. Conducting nitrogen 

tests on disturbed reference sites where revegetation eff orts have succeeded, as well as 

reference sites where revegetation eff orts have failed, can lead to determining a threshold 

value (Figure 5.34). Conducting soil tests on undisturbed reference sites, on the other hand, 

will defi ne the optimum nitrogen levels and also bracket target nitrogen levels. Converting soil 

test results into total nitrogen per acre is shown in Figure 5.35, line E.

Post construction soils are typically defi cient in nitrogen. In order to develop a strategy for 

bringing soil nitrogen above threshold levels, it is important to determine the approximate 

nitrogen defi cit. Figure 5.35 shows how this can be calculated by subtracting the total nitrogen 

value of post-construction soils (Line E) from the threshold nitrogen value (Line F).

Carbon Analysis – Carbon is determined directly using the combustion method 

(Leco instrument) or indirectly with the Walkley-Black and/or loss-on-ignition methods. The 

Walkley-Black and loss-on-ignition methods measure the percentage of organic matter that 

can be converted to the percentage of carbon by multiplying by a lab factor. Since carbon 

makes up between 50% to 58% of the organic matter (Tisdale and Nelson 1975), most labs will 
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Figure 5.36 – Raising nitrogen levels on nitrogen defi cient sites to threshold levels requires 

developing a long-term strategy. In this example, the site began with a background N of 650 

lb/ac. After application of a slow-release fertilizer at 1,000 lb/ac during the fi rst year, the site 

accumulated 50 lb N, assuming it was captured by plants or soil microorganisms and not 

leached from the soil. In the third year, another 3,000 lb slow-release fertilizer was applied, which 

increased total N to 850 lb/ac. By the 7th year, woody mulch that was applied during sowing 

had decomposed, releasing approximately 200 lb N. Nitrogen-fi xing plants were well established 

by then and contributed approximately 100 lb N.

1,300

1,200

1,100

1,000

900

800

700

600

500

400

300

200

100

0

1st Year

Slow-release

fertilizer

Threshold

Total N (lbs/ac)

3rd Year 7th Year

MulchBackground

N-Fix

BackgroundBackground

79

use a conversion factor within this range. For all tests, it is important to remember that soil labs 

sieve out any materials greater than 2 mm. Prior to sending the sample to the lab, sieve out the 

rock fraction but leave any organic matter in the sample. Request that the lab not sieve the 

sample so that the results report out all carbon and nitrogen. 

C:N – C:N is calculated by dividing % carbon by % nitrogen from the laboratory results obtained 

for nitrogen and carbon tests.

5.5.3.2 Mitigating for Low Soil Nitrogen

Develop a Strategy – It is important to develop a strategy for increasing nitrogen over time. 

It is not enough to just add fertilizer at seeding and call it good. On sites that are defi cient in 

nitrogen, a strategy must be developed that considers the accumulation of nitrogen over time 

by all available sources – topsoil, mulch, compost, fertilizers, and nitrogen-fi xing plants. Figure 

5.36 shows an example of a strategy for increasing total soil nitrogen to a threshold level.

Topsoil – Salvaging and reapplying topsoil is an excellent way to increase total soil nitrogen 

on drastically disturbed sites. The depth to apply topsoil should be similar to the soil depth 

found in undisturbed reference sites or pre-construction soils. If topsoil material is limited, then 

using the calculations shown in Figure 5.35 can help determine the minimum depths to apply 

topsoil. Section 10.1.4, Topsoil discusses methods to salvage and apply topsoil. To determine 

if there is, or could be, a tieup or surplus of nitrogen in the salvaged topsoil, soil tests should 

be conducted and evaluated for C:N. C:N greater than 25:1 could benefi t from the addition of 

nitrogen, while a ratio less than 8:1 will have available nitrogen for plant growth.

Composts – Applied on the soil surface and incorporated, composts can supply suffi cient soil 

nitrogen for long-term site needs. Application rates for composts can be calculated using 

methods shown in Figure 5.35. Testing and application methods for compost are discussed in 

Section 10.1.3, Mulches and Section 10.1.5, Organic Matter Amendments.
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Nitrogen-Fixing Plants – Signifi cant quantities of nitrogen can be supplied by nitrogen-fi xing 

plants (See Section 10.1.7, Benefi cial Soil Microorganisms). Establishing nitrogen-fi xing plants 

is a means of meeting short-term goals without having to amend with nitrogen fertilizers, and 

long-term goals by increasing the total nitrogen on the site.

Fertilizers – Applying nitrogen-based fertilizers to drastically disturbed soils is another means 

of increasing nitrogen levels, but it requires an understanding of fertilizers (composition 

and release), how the soils will capture and store nutrients, and how plants will respond to 

increased levels of available nitrogen. As the calculations in Figure 5.35 demonstrate, nitrogen 

based fertilizers cannot deliver enough nitrogen in one application for long-term site recovery 

of drastically disturbed sites. However, applied judiciously within an overall nitrogen strategy 

using topsoil, composts, and nitrogen-fi xing plants, nitrogen-based fertilizers can be an 

eff ective tool in site recovery. 

Not all sites or conditions require fertilizers. It might not be necessary to fertilize soils that have 

low C:N with nitrogen levels exceeding a minimum threshold level. In fact, applying fast release 

fertilizers may be a disadvantage on some sites by favoring weedy annuals over perennial 

species. A discussion on selecting fertilizers, calculating application rates, and determining 

methods of application are discussed in Section 10.1.1, Fertilizers.

Biosolids – Biosolids are rich in nitrogen and, if sources are available nearby, are a good means 

of raising soil nitrogen.

5.5.4 Nutrients

This section will broadly discuss the remaining mineral nutrients essential for plant growth 

(Figure 5.37). There are many references devoted to the role of nutrients in plant nutrition 

and the reader is directed to these sources for a more detailed discussion of each nutrient 

(Tisdale and Nelson 1975; Thorup 1984; van den Driessche 1990; Munshower 1994; Havlin and 

others 1999; Claassen 2006). The majority of research in soil fertility and mineral nutrients was 

conducted with the agricultural objective of optimizing crop yields through annual inputs 

of fertilizers, soil amendments, and irrigation. The primary objective of wildland restoration, 

however, is to restore or re-create self-sustaining plant communities that, once established, 

require very little input of resources. Unlike agriculture, revegetation of highly disturbed sites 

is not approached with the objective of optimizing the site for a single, high-yielding crop, but 

to develop a system of interrelated species that have evolved and adapted to site conditions. 

In wildland restoration, it is more important to re-create the components of the local soils than 

to change nutrient status based on agricultural models. For example, from an agricultural 

perspective, a serpentine soil has an imbalance of calcium and magnesium. Unless fertilizers 

containing a “correct” ratio of calcium and magnesium are applied to adjust this imbalance, 

the soils will be unsuitable for crop species. In wildland restoration, the approach is guided 

by the nutrient needs of the species endemic to the site, not to a generic agricultural crop. 

Since serpentine plant species have evolved on soils with these nutrient ratios, their nutrient 

requirements are vastly diff erent than those of agricultural crops, or even native vegetation 

growing on adjacent, non-serpentine soils. In this example, the calcium to magnesium ratio 

would not be seen as an imbalance for native serpentine plant establishment, but as perhaps a 

“requirement” for certain endemic species to recolonize the site. This requires the revegetation 

specialist to compare post-construction mineral nutrient status to that of undisturbed or 

recovered reference sites to determine if there are defi ciencies. Amendments can then be 

applied to bring nutrients and other soil factors to pre-disturbance levels or to levels that meet 

project revegetation objectives.

Success in wildland restoration is determined by its species richness, not biomass production, 

and being self-sustaining and resilient, not a system that requires constant energy inputs. 

By these standards, applying the basic agricultural model to wildland revegetation is limited. 

5.5.4.1 Nutrients – How to Assess

The objective of nutrient analysis is to compare nutrient levels of post-construction, disturbed 

soils with those of pre-disturbance, or reference site, soils. Where there are large discrepancies, 

a strategy can be developed to bring low post-construction levels up to minimum nutrient 

levels. Since this is a comparative analysis, it is essential that the sampling, collection, and 

testing methods are identical.
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Inset 5.2 – Soil Testing

Soil testing is a means of describing those soil characteristics that cannot be observed or 

accurately measured in the fi eld. The tests include analysis of chemical properties including 

pH, soluble salts, macronutrients, micronutrients, and organic matter, and physical 

properties such as density, water-holding capacity, and texture. Soil testing is costly and if 

not sampled, analyzed and interpreted properly can lead to unneeded and expensive soil 

amendments and application practices. In many respects, it is better not to test soils than to 

test them or interpret the results incorrectly.

Soil testing is performed with site survey, topsoil recovery, and reference site surveys 

(discussed in other sections) to 1) identify soil physical and chemical factors that will limit 

plant growth, 2) develop site-specifi c soil quality targets and 3) develop a set of revegetation 

treatments that will increase short and long term soil productivity targets. There are three 

components of soil testing – 1) soil sampling, 2) lab analysis, and 3) interpretation of lab 

results. Adhering to an established protocol for each component of soil testing is critical for 

developing appropriate revegetation treatments.

Sampling soil – Soil sampling is the fi eld collection of soils in a manner that best represents 

the soils of an area. The number of soil samples taken within a project area is usually kept 

to a minimum because of the expense of collecting and handling the samples and the 

cost of laboratory analysis. Taking a small amount of samples to describe a project site can 

be misleading, especially if the soils are extremely variable. This leaves the revegetation 

specialist with the challenge of determining the best approach to collecting soil samples in 

a way that most accurately represents the sites being described. 

The following guidelines are useful in developing a sampling strategy for soil testing:

Determine the area to be sampled – The areas to be sampled are called sampling areas and 

they are typically revegetation units, topsoil stockpiles or topsoil salvage areas, or reference 

sites. For most projects, sampling areas will have no more than one sample collected from 

each, therefore the selection of the site to collect soils samples (the collection site) must be 

representative of the sampling area. The sampling area and collection site are not always 

one and the same. Only for small sampling areas, such as topsoil stockpiles or reference 

sites, will the collection site be the same as the sampling area. For larger sampling areas, 

such as revegetation units or topsoil salvage areas, the collection site will be a smaller, 

representative areas within the sampling area.

Collect multiple subsamples – Once a collection site has been identifi ed, a set of subsamples 

are collected. Collecting soil from one point is never enough! The number of subsamples 

to collect within a collection site should be based on the site’s variability. Small collection 

sites generally require fewer subsamples than larger areas because there should be less 

variability. Undisturbed sites are typically more homogenous than disturbed sites and 

therefore require fewer subsamples. Guidelines for the numbers of subsamples to collect 

range from 6 for very homogenous sites to 35 for large, heterogenous sites. 

Randomly collect subsamples – Subsamples should be collected randomly within the 

collection site. For small areas like reference sites or stockpiled soil, the samples can be 

collected on a grid system. For very large areas, samples can be collected in a zigzag or 

“W” pattern at predetermined intervals.

Determine sampling depth – Review the objectives for soil sampling and determine the 

sampling depth. If the objective is to characterize the soil for topsoil recovery, then the soil 

samples must be collected only in the topsoil horizon, in which case the depth of the topsoil 

would have to be determined prior to sampling. If it is known that the surface soil including 

duff and litter will be removed to 15” during topsoil salvage, then collection depth would be 

a sample 15” deep that included the duff and litter layers. If soil sampling objectives are to 

determine the nutrient and mycorrhizal status of a topsoil pile, the entire pile is the sampling 

zone and the subsamples must be collected from various depths within the piles as well 

as around the pile to obtain a representative sample. (If the surveyor felt that the interior 

of the pile was signifi cantly diff erent in nutrient status or mycorrhizae, then the pile could 

be stratifi ed into collection sites – the exterior of the pile and the interior – and sampled 

separately.) Sampling of the subsoil is important because this will give an indication during 

planning of how the disturbed site will appear after construction and before mitigation.
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Collect a representative slice of soil – It is important to evenly sample the predetermined 

depth of soil. For example if the sampling depth is 0 to 15 inches deep, then the entire 

section of soil must be equally sampled for each subsample.

Mix subsamples – Place subsamples in a clean bucket and mix thoroughly. From the 

composite subsamples, remove the required amount of soil to send to the lab for analysis.

Determine coarse fragment content – If the soils are high in coarse fragments, the samples 

can be sieved in the fi eld using a 2mm sieve. This will reduce the amount of sample weight to 

haul out of the survey area and give an estimate of the coarse fragment content; otherwise, 

sieve back at the offi ce prior to sending to the lab. If the samples are wet or moist, they will 

need to be air dried prior to sieving. Record the percent coarse fragment content for the 

sampling area which includes large and small coarse fragments. This information will be 

used later to modify the lab results.

Selecting a lab – The criteria for selecting a soil lab is typically based on costs, turnaround 

time, analytical tests and consulting services. Most labs off er a general test package for under 

$50 per sample (2004 prices) and deliver the results within two weeks of receiving the soil 

samples. For an added fee, laboratories will interpret the results of the analysis. While these 

are important reasons for selecting a lab, the primary criteria for selecting a lab should be 

based on the quality of the testing facilities.

A common assumption is that all labs are of similar quality in their analytical testing, and 

that if a group of labs were sent the same soil sample they would report similar results 

for most tests. This is not typically the case, as several university reviews of laboratories 

have shown (Neufeld and Davison 2000; Rose 2004). In one comparison, eight reputable 

laboratories reported widely diff ering results for all soil nutrients when sent identical soil 

samples (Rose 2004). One reason for the variation in results is that there are usually several 

testing procedures that can be used to quantify a soil parameter. Some methods have 

greater accuracy and precision than others. The soil testing industry at this time has not 

settled on an agreed upon set of analytical methods to use. Even when the same tests are 

performed, labs often report diff erent levels of accuracy (Rose 2004).

Soil laboratories can voluntarily participate in a testing program called the North American 

Profi ciency Testing (NAPT) program that will assess the quality of their analytical procedures. 

In this program, NAPT periodically sends all participating labs identical soil samples. Each 

lab analyzes the samples for mineral nutrients using established analytical procedures, then 

sends the results back to NAPT. The results from all labs are compiled and analyzed statistically 

and each lab is sent a report on how their results compared to the other participating labs. 

NAPT suggest that the accuracy be less than 10% of industry values and precision no greater 

than 15% of industry values (Neufeld and Davison 2000). These reports are not available to 

the public but laboratories might share them if asked. NAPT is not a certifi cation program 

but is often a basis for a soil lab quality control program.

The following is a checklist for selecting a high-quality lab (modifi ed from Neufeld and 

Davison 2000):

9 Does the lab have a quality control program? If they do, ask them to explain it.

9 Does it participate in a profi ciency testing program (like NAPT)?

9 Will they share the results of profi ciency testing program with you?

9 Does the lab use established analytical methods (the most appropriate for soils in the 

geographic area being tested)?

If you receive no for the answers to any of these questions, another soil testing facility should 

be considered. If the selection is down to a couple of labs, consider sending duplicate soil 

samples with known properties (“checks”) to each lab and compare the results using the 

NAPT suggested standards for accuracy and precision. Soil “checks” can be purchased 

through a profi ciency testing program. Once a lab is selected, continue to ask for quality 

control reports. If the budget allows, periodically send duplicate “check” soil samples with 

your regular soil samples to assess accuracy and precision.
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Cl

Mg S Ca

Mo Cu Zn

P K N

Mn Fe B

Mineral Nutrient Group

Macronutrients

Secondary Macronutrients

Micronutrients

Nitrogen – N

Major fertilizer component that is most commonly 

limiting in disturbed soils. Legumes and other 

plants fix atmospheric nitrogen in natural plant 

communities. 

Phosphorus – P

Major fertilizer component that is frequently 

unavailable in disturbed soils. Mycorrhizal 

fungi improve uptake in natural plant communities. 

Elements &

Symbols

Application to Restoration of 

Distributed Soils

Calcium – Ca

Magnesium – Mg

Besides being plant nutrients, calcium and 

magnesium can be applied as dolomitic 

limestone to raise soil pH. 

Sulfur – S Besides being a plant nutrient, sulfur can be 

applied to lower soil pH. 

Boron – B

Manganese – Mn

Iron – Fe

Zinc – Zn

Molybdenum – Mo

Copper – Cu

Chloride – Cl 

More important for subsequent plant growth 

than for establishment. Micronutrients are 

frequently unavailable in disturbed soils, but 

special formulated and balanced micronutrient 

fertilizers must be used. 

Potassium – K Major fertilizer component that is easily leached 

from soils. 

Figure 5.37 – The 13 essential mineral nutrients.

83

Nutrient testing should be performed on: 1) salvaged topsoils, 2) reference sites, 3) postconstruction soil materials, and 4) amended soils. A guide to sampling soils for nutrient analysis 

is presented in Inset 5.2. Nutrient testing should evaluate total soil nutrient levels (long-term 

nutrient availability) as well as available levels (immediately available nutrients). Table 5.1 lists 

soil tests common to the western United States.

With soil laboratory results from reference sites and post-construction sites, determine which 

nutrients, if any, are defi cient using a process outlined in Section 10.1.1.2, Develop Nutrient 

Thresholds and Determine Defi cits. If a nutrient is found defi cient, fertilizers, composts, topsoils, 

or other organic amendments can be applied to the soil to bring the nutrient above threshold 

levels. A process for determining fertilizer type, application rates, and application methods is 

presented in Section 10.1.1, Fertilizers.

5.5.4.2 Mitigating for Low Nutrients

Topsoil – Salvaging and reapplying topsoil is important for restoring nutrients to preconstruction levels, especially on sensitive soils (e.g., serpentine and granitic soils). The depth 

to apply topsoil should be at levels found in undisturbed reference sites or pre-construction 

soils, or can be calculated by methods described in Figure 10.25 in Section 10.1.4, Topsoil.

Compost – Incorporating composts is a good method for increasing nutrients to predisturbance levels. Determining which type of compost to select and how much to apply is 

discussed in Section 10.1.5, Organic Matter Amendments.
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Available

Available

Available

Available

Available

Available

Available

Available

Slowly -

Available

Total

Total

Total

Total

Total

Available

Available

Available

Available

Available

Available

Available

Available

Available

Available

Available 

Hot-Water

Aqueous extract of a soil paste

Ammonium Acetate

Aqueous extract of a soil paste

Ammonium oxalate-oxi acid extraction

Aqueous extract of a soil paste

(Saturated paste)

CaO extract & Cd reduction

KCL Extraction

Anaerobic Incubation

Kjeldahl N

Combustion (Leco Instrument)

Loss - Ignition

Walkley-Black Method

Combustion (Leco Instrument)

Aqueous extract of a soil paste

(saturated paste)

Olsen Sodium Bicarbonate

Dilute Acid-Flouride (Bray-P1)

AB-DIPA

Sodium Acetate

Olsen Sodium Bicarbonate

Ammonium Acetate

Ammonium Acetate Displacement

CTPA

Aqueous extract of a soil paste

(saturated paste)

CaHPO4

 & ICP

CTPA 

In semi arid to arid soils

Accepted extrant for 

western soils

Best used for soil high in 

organic matter

Reports out at half the rates 

of Olsen method

Iron is not performed in Oregon

because not found deficient

For arid and semi-arid soils

For arid and semi-arid soils

For mesic sites

Reports out in Total C

Boron

Boron

Calcium, Magnesium

Calcium, Magnesium

Molybdenum

Nitrate

Nitrate

Nitrogen

(ammonium and nitrate)

Nitrogen

(Mineralizable)

Nitrogen (Total)

Nitrogen (Total)

Organic Matter

Organic Matter

Organic Matter

pH

Phosphorus

Phosphorus

Phosphorus

Potassium

Potassium

Potassium

Sodium

Sodium

Sulfate Sulfur

Sulfate Sulfer

Zinc, Copper, 

Manganese, Iron

Tests Type Test Method Notes

Table 5.1 – Common soil testing methods for the western United States (Horneck and others 

1989; Munshower 1994; Teidemann and Lopez 2004). Note: Composts use a diff erent set of 

tests due to the high organic matter (See Section 10.1.4, Topsoil and Section 10.1.5, Organic 

Matter Ammendments).

84
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Fertilizers – As discussed in Section 5.5.3, Soil Nitrogen and Carbon, fertilizers should be used 

within an overall nutrient strategy. See Section 10.1.1, Fertilizers, for a discussion on application 

methods, fertilizer types, timing, and other important aspects of fertilization.

Biosolids – Biosolids are rich in nutrients. If sources are available and transportation economical, 

this is a good way to add nutrients to disturbed sites.

5.5.5 pH and Salts

pH is the measurement of soil acidity or alkalinity, based on a logarithmic scale of 0 to 14. Soils 

with pH values below 7 are acidic, and those above 7 are basic. Basic soils have high amounts 

of bases (positively charged ions), such as calcium, magnesium, potassium, sodium, and 

phosphates. Basic soils have developed under arid and semi-arid climates and are found east of 

the Cascades and Sierra Mountains, throughout the Basin and Range province. Acidic soils have 

formed in wetter climates, where the continued movement of water through the soil profi le 

has leached the bases from the soil. Acidic soils are found west of the Cascades and Sierra 

Mountains, and are most prevalent in the coastal ranges. Topsoils are typically more neutral 

when compared to underlying subsoil, whether the soils are acidic or basic. In some cases, the 

topsoil buff ers the plant root systems from the underlying, inhospitable subsoil conditions. 

When topsoils are removed during construction, subsoils become the growing environment 

and, unless mitigating measures are taken, the results are disastrous for plant establishment.

Soil acidity or alkalinity, as measured by pH, aff ect mineral nutrient availability, mineral toxicity 

(Palmer 1990), and nitrogen fi xation (Thorup 1984). In acid soils, the ability of plants to utilize 

many nutrients decreases, especially for calcium, and magnesium. As soil pH becomes more 

acid (less than 4.5), aluminum becomes more soluble and more toxic to plant growth. Low pH 

soils also hinder the establishment of nitrogen-fi xing plants, such as legumes (Bloomfi eld and 

others 1982). Signifi cant loss of rhizobia viability has been documented at pH levels less than 6 

(Brown and others 1982).

Basic soils with pH values of 8.0 or greater indicate the presence of calcium carbonate 

(Thomas 1967). Calcium and magnesium are at such high levels that they can interfere with 

the uptake of other nutrients, notably phosphorus, iron, boron, copper, zinc (Campbell 1980). 

High pH soils typically have high salt levels, which can also restrict the growth of many plants. 

For example, as soil pH approaches 9, sodium concentrations become toxic to plants (Tisdale 

and Nelson 1975).

Soil salinity is the measure of the total amount of soluble salts in a soil. The term soluble salts 

refers to the inorganic soil constituents, or ions, that are dissolved in the soil water. The principal 

soluble salts in a soil contain the cations sodium, calcium, and magnesium, and the anions 

chloride, sulfate, and bicarbonate (Landis and Steinfeld 1990).

Almost all plants are susceptible to salt injury under certain conditions, with germinants and 

young seedlings being particularly susceptible to high salt levels (Figure 5.39). Soluble salts can 

injure plants in several ways:

Figure 5.38 – Most portable pH meters 

will also measure salts (electrical 

conductivity). Some probes can be directly 

inserted into the saturated media and a 

reading taken. The sample is prepared 

by adding distilled water just to the point 

when the surface glistens and allowed to 

come to equilibrium after 15 minutes.
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1,000

2,000

3,000

2,500

1,500

500

3,500

Soluble Salts

 mS/cm or mmhos/cm

High Salt 

Hazard -

Damage 

to Plants

Moderate

Salt Hazard -

Injury to

Germinants

Low Salt

Hazard

Figure 5.39 – Soluble salts will injure 

germinants and, at high concentrations, 

can damage established plants. (Values 

are based on the SME method of 

conductivity measurement.)

86

1) Reduced soil moisture. Salts can lower the free energy of water molecules, causing an 

osmotic eff ect and thereby reducing the moisture availability to plants.

2) Reduced soil permeability. High salt concentrations (specifi cally sodium salts) can 

change the soil structure by reducing the attraction of soil particles, causing them 

to disperse. Pore space is lost and air and water movement within the soil profi le 

are restricted.

3) Direct toxicity. High levels of certain ions, including sodium, chloride, and boron, can 

injure plant tissue directly.

4) Altering nutrient availability. Certain nutrients as salts can change the availability and 

utilization of other plant nutrients (Landis 1981; Landis and Steinfeld 1990).

High salt levels can be found in arid climates where there is inadequate rainfall to leach salts out 

of the plant root zone. Topsoils tend to be lower in salts than subsoils, so during construction 

when topsoil is removed, the resulting soils can be very high in salts and pH. In addition, high 

salt concentrations can be created by poor soil drainage resulting from compaction; when 

excessive amounts of fertilizer, manure, or compost are applied; or when de-icing chemicals 

applied to roads run off and enter the soil (Parent and Koenig 2003).

5.5.5.1 pH and Salts – How to Assess

The pH and soluble salts tests are standard analytical measurements that should be run for 

all soil samples sent for nutrient analysis. pH tests should also be run on soil organic matter 

amendments considered for mulch or incorporation into the soil. These tests are accurate, with 

pH results diff ering between laboratories by 0.1 to 0.2 points (Thomas 1967). pH and soluble salts 

can also be tested by the revegetation specialist on site or back at the offi ce using reasonably 

priced equipment. When considering purchasing a portable pH meter, be sure that it will also 

measure soluble salts and that it has a tip that can be submerged easily in a soil slurry.

The most accurate method of assessing pH and salinity is through lab analysis. However, 

quick, reliable estimates can be made with a hand-held pH/electrical conductivity meter using 

the Saturated Media Extract (SME) method for preparing samples (Figure 5.38). This method 
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requires a small amount of soil (50 cc) be placed in a jar. Just enough distilled water is stirred 

into the soil to make the surface “glisten” but not readily fl ow. The mixture is allowed to stand 

for approximately 15 minutes. If the probe can be inserted into the soil so that the sensors are 

completely covered, then a pH and conductivity reading can be directly made. If the probe can 

not be submerged in the slurry, then a larger sample of soil or a gravity or vacuum fi ltration 

system solution should be used to extract enough water to test.

5.5.5.2 Mitigating for Low pH Soils

Apply Liming Materials – Raising the pH through the application of liming materials is a 

common agricultural practice that can be applied to revegetating road sites (See Section 10.1.6, 

Lime Amendments).

Apply Appropriate Fertilizers – Some commercial fertilizers, especially ammonium-based 

fertilizers such as ammonium nitrate, ammonium sulfate, and ammonium phosphate, will 

reduce pH (Havlin and others 1999) and should be limited on acidic soils. Fertilizers that have 

calcium, magnesium, or potassium in the formula are more appropriate for low pH soils. 

Examples of these fertilizers are calcium nitrate, potassium nitrate, magnesium sulfate.

Apply Lime With Organic Matter – Incorporation of lime will lower pH. On acid soils, 

application of lime with organic matter will raise the pH of the soil (See Section 10.1.6, 

Lime Amendments).

Apply Topsoil – Where topsoils have been removed leaving very basic or very acidic subsoils, 

reapplying topsoil or manufactured topsoil can moderate pH levels.

5.5.5.3 Mitigating for High pH Soils

Apply Sulfur – Agricultural soils can be treated with sulfur to lower pH, but high quantities of 

sulfur and irrigation must be applied to lower the pH just slightly (Havlin 1999). The use of sulfur 

in wildland revegetation therefore is not a widely practiced method.

Irrigation – Applying irrigation water is another method of reducing soil pH by leaching out 

bases. However, the amount of water needed to lower pH levels can be very high; in most cases, 

using irrigation is not a viable mitigating measure. It is also diffi cult to fi nd irrigation water in 

arid environments that is low in bases and salts. Applying irrigation water high in bases will 

raise pH and salt levels in the soil, compounding the problem.

Apply Organic Matter – Incorporated composts or other types of organic matter can lower soil 

pH as the organic matter decomposes (Havlin and others 1999). For arid sites, however, the pH 

and conductivity of the organic matter must be tested prior to purchase to avoid the possibility 

of introducing organic matter high in salts.

Add Nutrients – To compensate for the tie-up of certain nutrients, the addition of nutrients 

through fertilization might be considered. The benefi ts of using fertilizers on arid soil must be 

off set by the possibility of creating fertilizer salt problems.

5.5.5.4 Mitigating for Salts

Since high levels of soluble salts are usually caused by poor soil management, the key to 

mitigating high salinity is to avoid creating the conditions that could potentially cause those 

levels. In soils where internal drainage is poor, prevention may be the only feasible approach 

for reducing salt problems.

Avoid Mulch or Soil Amendments With High Salinity – Testing all materials to be applied to 

the site will aid in the prevention of increased salt levels in the soil. Amendment materials with 

electrical conductivity readings in excess of 1,000 mS/cm should be avoided.

Reduce Commercial Fertilizers – Some commercial fertilizers, control-release fertilizers (CRF) 

in particular, can signifi cantly increase the soluble salts found in the soil. This can be a major 

problem when using CRF in arid conditions. The fertilizer will begin to release following wet, 

warm spring conditions, but will not be leached through the soil without signifi cant rainfall 

through the summer. Salts can build up to damaging levels, both on the surface and in the 

plant root zone.

Apply Gypsum With Irrigation – Incorporation of gypsum (calcium sulfate) followed by 

leaching can be eff ective in situation where sodium is the cause of high soluble salts (e.g., 
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de-icing materials have been applied to roads). The calcium in gypsum will displace sodium 

and the sodium will then leach out of the soil profi le with irrigation or rainfall (UMES 2004).

Irrigation – Application of irrigation water could potentially leach the salts from the soil. 

The amount of water depends on the soil type. In arid soils, application of 6 inches of water 

can reduce salinity levels by 50%; 12 inches can reduce by 80%; and 24 inches can reduce by 

90% (UMES 2004). Application of irrigation water would need to take place over several days. 

However, for most sites, this is not practical due to high costs.

5.6 SURFACE STABILITY

Surface stability is the tendency of the soil to remain in place under the erosive forces of rain, 

wind, and gravity. Good surface stability is essential for establishing plants, reducing erosion, 

and maintaining high water quality. If the soil surface is unstable, seeds will wash or blow away. 

They can also move downslope through freeze-thaw or gravity before they can germinate. 

The same processes that stabilize seeds will also stabilize the soil surface. As soil is removed, 

soil productivity is reduced. With excessive erosion, plant roots are exposed, increasing the 

possibility of seedling mortality.

Site factors that infl uence surface stability and soil erosion are:

 · Rainfall and wind,

 · Freeze-thaw,

 · Soil cover,

 · Surface strength,

· Infi ltration rates,

 · Slope gradients,

 · Surface roughness, and

 · Slope lengths.

All surface erosional processes start first with the detachment of soil through the forces of 

rainfall, wind, or frost heave. These forces loosen seeds and soil, making them more susceptible 

to transportation off the site. Water moving over the surface of the soil during rainstorm 

events is the primary factor in moving seeds and soil into stream channels, resulting in lost 

seeds and water quality problems. This occurs when infi ltration rates (the rate water moves 

through the soil surface) are lower than rainfall rates. If slope gradients are steep, slope lengths 

are long, or surface roughness is low, surface water picks up energy and transports greater 

and greater amounts of soil and seeds downslope. As this energy increases, eventually water 

becomes concentrated with force to cut through the surface of the soil, creating rills and gullies. 

The degree to which soils detach is directly related the percentage of soil cover protecting the 

soil (more cover, less erosion) and to the soil strength, or the capacity for individual soil particles 

to hold together under erosional forces. The result of soil erosion can often be detected on road 

cuts by noting how much sediment is in the ditch line. If the ditch is full of recently deposited 

sediment (recently deposited sediment usually lacks vegetation), there is a good chance that 

Figure 5.40 – Wind erosion not only 

blows seeds, soil, and mulches off the 

soil surface, it will also expose roots of 

established plants. Non-cohesive soils, 

like sands and silts, are most prone to 

wind erosion.
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sediment came from the cut slope. An inspection of the surface of the cut slope will indicate if 

the sediment originated there. Gravels, cobbles, and even small plants will show the results of 

soil movement.

5.6.1 Rainfall and Wind

Each site has unique rainfall and wind patterns that will aff ect the stability of the soil surface. 

High rainfall intensities and high winds can move seeds and soil particles off -site through 

erosional processes. In water erosion, raindrops begin the erosion process. Raindrops have been 

likened to small bombs. In heavy rainstorms, they fall with such force (possibly between 15 and 

20 miles per hour) that, when they hit the soil surface, they create an impact that can blast the 

soil or seeds several feet away. Raindrops leave behind small craters that are compacted and 

sealed with fi ne soil particles, reducing infi ltration rates.

The intensity of rainfall determines how much soil is detached. A high intensity rainfall will 

detach more soil particles than a low intensity rainfall. But detachment is only one aspect of 

erosion; it takes surface runoff to move soil and seeds downslope. If an intense rainstorm lasts 

only a short period of time, there will be insuffi cient water to exceed infi ltration rates and water 

will absorb into the soil. If the duration is long, some water will not enter the soil, but will run 

over the surface carrying soil and seeds downslope. The most critical weather events, therefore, 

are those that bring high intensity rainstorms of long duration. These typically occur during 

major summer thunderstorms or Pacifi c winter storm systems. Precipitation in the form of 

snow is not typically a problem for surface erosion. Snow protects the soil surface from rainfall 

splash, and snowmelt usually occurs at such slow rates that even soils with low infi ltration can 

absorb the water.

When projects are located in areas of high winds, surface soils will be susceptible to wind 

erosion. Wind forces will detach soil particles and seeds and move them off site. In extreme 

conditions, high winds can remove several inches of surface soil, exposing roots (Figure 5.40).

5.6.1.1 Rainfall and Wind – How to Assess

It is unlikely that climate reports or weather records will give the duration and intensities of 

rainfall events for site level planning. Digital rainfall gauges are available that record the amount 

of rainfall and time it occurred. This information is used to determine duration and intensity. 

While the cost of this equipment is high, it is becoming more aff ordable. There are many types 

of digital rain gauges available, ranging in price and quality. It is important to select a digital 

rain gauge that is rugged, self maintaining, and can record for long periods of time.

Permanent wind speed equipment is available, but most likely beyond the reach of most project 

budgets. Site visits during diff erent times of the year give some indication if wind is a problem. 

Site characteristics, such as position on slope (ridgelines are more prone to wind than valley 

fl oor) or proximity to forested environments (forests often reduce wind speeds) can be used to 

infer wind forces. Vegetation can also indicate the eff ect of wind. For example, prevailing winds 

can be determined from the growth habits of trees and shrubs on site. Local residents may also 

provide some information on local weather events.

Assessing the risk of wind erosion can be determined by knowing soil texture. Those soils most 

prone to wind erosion are non-cohesive soils, ranging from silts to coarse sands. Clay soils 

(cohesive soils) and very rocky soils are far less prone to wind erosion.

Figure 5.41 – Continual freeze-thaw 

conditions can push root systems of 

planted seedlings out of the ground, 

reducing growth and potentially 

killing seedlings.
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5.6.1.2 Mitigating for High Rainfall and Wind

Minimize Disturbance – In areas of high rainfall 

or sites where water quality values are high (near 

streams or rivers), the best engineering design 

is to keep the footprint of the construction 

project disturbance to a minimum. Not 

only does this reduce the risk of delivering 

sediment to the aquatic system, it can reduce 

project costs by reducing the amount of area 

needing revegetation.

Integrate Erosion Practices – In disturbed 

sites, especially those near streams, the 

integration of erosion practices with plant 

establishment techniques off ers the best 

approach to stabilizing the soil surface. These 

include practices such as increasing soil cover, 

shortening slopes, reducing slope gradients, 

leaving roughened surfaces, increasing 

infi ltration rates, and quickly establishing native 

vegetative cover. These will be covered in the 

following sections.

Use Appropriate Mulching Practices –

Assessing the potential for high winds on 

the site should be considered when applying 

mulches because mulches can be removed 

from the soil surface under strong winds. Some 

materials, such as wood strand mulches (See Section 10.1.3.10, Wood Strands), have been tested 

under high wind conditions and, because of higher weights and interlocking particles, these 

materials are more resistant to high winds. Lighter mulch materials, such as straw and hay, are 

more susceptible to removal by winds.

On windy sites, straw and hay are often crimped into the soil, but this operation can also cause 

soil compaction. Tackifi ers used with hydromulches are used eff ectively to stabilize straw and 

hay mulches. Mulches placed on roughened soil surfaces can also reduce the potential that the 

mulches will be lost by wind.

Place Large Woody Matierial – Down woody material such as trees and large bran ches can 

bock the soil surface from wind and rainfall.

5.6.2 Freeze-Thaw

Freeze-thaw is the process of ice formation and ice melting that occurs within the surface of the 

soil. In this daily cycle, temperatures drop at the soil surface at night and water begins to freeze 

within the soil pores, creating ice crystals. As ice crystals continue to form, water is drawn from 

the soil below through capillary action to replace the water that created the ice crystals. During 

freezing, ice crystals expand in the soil and push soil aggregates apart (Ferrick and Gatto 2004), 

weakening the internal structure of the soil. When soils thaw during the day, soil strength 

has been greatly reduced (Gatto and others 2004), leaving the soil surface signifi cantly less 

resistant to erosional forces. Freeze-thaw is considered one of the least understood aspects of 

soil erosion (Ferrick and Gatto 2004) and yet accounts for signifi cant annual soil losses (Froese 

and others 1999).

The formation of ice crystals will destabilize the seed germination environment. Freeze-thaw 

cycles aff ect germinating seeds by creating ice crystals that physically push the germinating 

seeds above the soil surface, exposing the emerging roots to extremely harsh conditions for 

seedling establishment, including low humidity, high temperatures, and sunlight. On steeper 

slopes, soil particles and germinating seeds will move downslope after each freeze-thaw cycle, 

further destabilizing the seed germination environment. Freeze-thaw processes can also aff ect 

seedling establishment. Long periods of freeze-thaw cycles can push container seedlings out 

of the ground, exposing roots and, in many cases, killing seedlings (Figure 5.41).

Figure 5.42 – Ice crystals that form 

under freeze-thaw conditions can lift soil 

particles over 2 inches above the original 

surface. Later in the day the crystals will 

melt and the particles will drop.
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Soils most susceptible to freeze-thaw eff ects are those: 1) with a high silt content (or compacted 

sands), 2) with an adequate supply of soil moisture, and 3) that are cold. Silt-sized particles 

have pore sizes that are small enough to pull moisture to the freezing front through capillary 

action, yet large enough to form ice crystals (Ballard 1981). Soils with coarse textures, like sands, 

do not provide good capillary rise because the pores are too big; fi ne-textured soils (high in 

clay) have good capillary characteristics, yet do not have large enough pores for ice crystals 

to form (Ferrick and Gatto 2004). Sands have been reported to be frost-susceptible when they 

are compacted because the size of the pores is reduced, encouraging capillary rise (Gatto and 

others 2004). Soil cover, which includes litter, duff , and organic mulches, do not typically have 

good capillary rise characteristics, and therefore are less frost-susceptible. In addition, soil 

cover off ers good thermal protection, which moderates the degree of freezing and thawing 

at the soil surface. The eff ects of freeze-thaw on surface stability increases as slope gradients 

steepen; the steeper the slopes, the greater the movement of seeds and soil downslope each 

day. Consider a seed or soil particle on a steep slope that experiences a 2 inch rise on top of 

an ice crystal (Figure 5.42); when the crystal melts, the seed or soil particle drops to a diff erent 

point further downslope. After many freeze-thaw cycles, the distance traveled by the seed or 

soil particle can be signifi cant.

5.6.2.1 Freeze-Thaw – How to Assess

Freeze-thaw processes occur typically in the spring and fall, when soil moisture levels are high 

and soil temperatures are cold. Soil surfaces that have undergone freeze-thaw cycles will have 

a very loose crust that will collapse when touched or walked upon. Gravels are often perched 

on pedestals, but give way under light pressure.

Project areas with bare surface soils high in silts should be considered prone to freeze-thaw 

processes in the spring or fall. Compacted soils high in sands are also susceptible. Soils with 

deep mulch or litter layers are less susceptible.

Figure 5.43 – Soil cover protects the 

surface from rainfall impact. Not only is 

soil removed during rainstorms, aff ecting 

germination and seedling establishment, 

but seedlings that do emerge can be 

covered with soil that splashes from 

rainfall impact. Seedlings will not grow 

through an encasement of soil.

Figure 5.44 – Larger materials, such as 

gravels (A) and wood chips (B), protect 

the soil and sown seeds by absorbing 

the energy of rainfall impact. While 

unprotected soil and seeds are removed 

through splash and sheet erosion, 

protected soil remains in pedestals, 

sometimes several inches above the 

surface of the soil. Seeds that do remain 

on or near the surface have a diffi cult 

time germinating through the surface 

crust created by rainfall impact (C). 

Plants that do establish will have roots 

exposed by successive rainfall events.
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5.6.2.2 Mitigating for Freeze-Thaw

Apply mulch. Available research on the mitigation of freeze-thaw eff ects is slim, but it can be 

assumed that practices that insulate the soil surface and increase pore sizes will reduce some of 

the eff ects of freeze-thaw. The addition of organic mulches will provide insulation. The deeper 

the mulch layer, the less propensity for freeze-thaw at the surface. Hydromulch applications at 

typical rates of 1,000 to 2,000 lb/ac are not deep enough to moderate surface temperatures, or 

strong enough to resist the destabilizing eff ects of ice crystal formation on surface strength. 

Mulch applications that are too deep will bury the seeds, and seedlings will not emerge. In this 

case, using mulches such as pine needles and wood strands are options because application can 

occur at greater thickness but still allow light through for seedling emergence. If ice crystals do 

form and push newly emerged seedlings from the ground, these types of mulches will protect 

portions of exposed roots within the mulch layer from drying out, while also preventing the 

lifted soils from moving downslope by gravity (See Section 10.1.3.10, Wood Strands and Section 

10.1.3.11, Litter and Duff ). For planted seedlings, the application of very deep mulches should 

reduce the eff ects of freeze-thaw.

Till Compacted Soils – Sandy soils are very susceptible to freeze-thaw if they are compacted. 

Loosening soils through tillage is perhaps the best method of mitigating the eff ects of freezethaw on these soil textures (See Section 10.1.2, Tillage).

Avoid Wet Soils – Planting or sowing in soils with high water tables and poorly draining soils 

should be avoided. The extra moisture in these soils will feed ice crystal formation, creating a 

risk to establishing seedlings.

Maintain Some Overstory Canopy – Trees and shrubs will moderate surrounding temperatures, 

reducing the potential for freeze-thaw.

5.6.3 Soil Cover

Soil cover is the layer directly above the surface of the soil. In an undisturbed environment, soil 

cover is composed of duff , litter, live plants, and rock. Soil cover is very important for surface 

stability because it dissipates energy from rain drop impact before it reaches the surface of 

the soil. A good cover can protect the soil from high intensity rainfall events. Furthermore, if 

overland fl ow should occur during storm events, soil cover will slow the movement of runoff 

and capture sediments and seeds before they move downslope. Section 5.4, Water Loss, 

discusses how soil cover was important for reducing evaporation; this section will discuss its 

role in stabilizing the soil surface and reducing erosion.

When the soil surface lacks cover, it is subject to the direct forces of raindrop impact, overland 

fl ow, wind, and gravity. These forces not only move soil off site, aff ecting water and air quality, but 

they also displace seeds or remove soil from around newly developing seedlings (Figure 5.43). 

A lack of soil cover will impact revegetation objectives by reducing the quantity of seeds that 

will germinate. Seeds that do germinate will be negatively aff ected by soil splash and sheet 

erosion that removes soil from around the seedling roots. The severity of soil erosion and seed 

movement is directly related to the percentage of bare soil.

After construction, most organic soil cover is removed. What remains is bare soil and coarse 

fragments (gravel, cobble, and stone). Left unprotected, bare soil will erode during rainstorms, 

leaving a pavement of gravel, cobble, and stone. If the amount of coarse fragments in the soil 

is high, then the percentage of the soil surface covered by coarse fragments will also be high. 

By the third year, erosion rates on unprotected bare soils typically fall to a tenth of the rate of 

the fi rst year rate because of the formation of a soil cover of coarse fragments (Megahan 1974; 

Ketcheson and others 1999). While this process produces less sedimentation to stream systems, 

the high coarse fragments at the soil surface are not a good environment for seed germination. 

For this reason, it is important to quickly stabilize the soil surface after soil exposure; this is 

one of the reasons that road specifi cations call for temporary road stabilization during the 

construction period.

5.6.3.1 Soil Cover – How to Assess

Soil cover can be measured by establishing transects and recording the percentage of rock, 

vegetation, litter, duff , and bare soil. A monitoring protocol for measuring soil cover is presented 

in Chapter 12.
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Inset 5.3 – Bottlecap Test for Surface Stability

(from Herrick and others 2005a)

Place a soil fragment in a bottle cap fi lled with 

water. Watch it for 30 seconds. Gently swirl the 

water for 5 seconds. Assign one of three ratings:

M = Melts in fi rst 30 seconds (without 

swirling) – Not stable

D = Disintegrates when swirled (but does 

not melt) – Moderately stable

S = Stable (even after swirling) – Stable 93

5.6.3.2 Mitigating For Low Soil Cover

The primary objective of most revegetation projects is to stabilize the soil surface and create an 

optimum environment for seeds to germinate and plants to establish. Initial surface stabilization 

must remain eff ective until plants become established and protect the surface from erosion 

through vegetative cover. Therefore, the selection of surface stabilization methods must be 

based on: 1) the eff ectiveness as a soil stabilizer, 2) the quality as a seed germination and plant 

establishment environment, and 3) longevity.

Apply Mulch – There are a variety of mulches with varying qualities and longevities which 

should be considered based on the erosional potential and revegetation needs of each site 

(See Section 10.1.3, Mulches). Short-fi ber mulches, such as wood fi ber and paper mulches, 

applied with a tackifi er are very eff ective in protecting the soil from rainfall impact. However, 

after a year, these mulches are usually no longer eff ective. On many sites, protection for a year 

is adequate for establishing a good vegetative cover. On sites that are cold, arid, or semi-arid, 

the establishment of vegetative cover can take longer than one year (Figure 5.45). On these 

sites, soil surface protection will require longer-lasting mulches such as straw, pine needles, 

hay, wood chips, wood strands, or erosion fabrics.

5.6.4 Surface Strength

When soil cover is removed, the surface of the soil is exposed to the erosive forces of raindrop 

impact, surface fl ow, freeze–thaw, and wind. How strongly soil particles bind together 

determines how much soil particles are detached and moved by these forces. Topsoils with 

good aggregation and high organic matter will be more stable than subsoils or soils low in 

organic matter. Soils high in clays have greater strength than sands and silts, which lack 

cohesiveness. Seeds have no cohesive properties and, when sown on the surface of the soil 

without mulches or tackifi ers, are very susceptible to erosive forces.

5.6.4.1 Surface Strength 

– How to Assess

Determining the soil texture of 

the surface soil is a simple way to 

determine soil strength (See Section 

5.3.1, Soil Texture). Soils low in clays 

(<15%) and high in sands will have 

low surface strength (Figure 5.46). 

In most cases, soils lacking topsoil 

will have reduced surface strength 

due to the lack of roots and organic 

matter that hold the soil particles 

together. The rainfall simulator can 

Figure 5.45 – Semi-arid, arid, and cold sites often take more than one year to fully revegetate. 

Photo A shows the vegetative establishment one year after hydroseeding on a semi-arid site; 

bare soil exceeds 60%. Photo B shows the same site almost 2 years after sowing; vegetation has 

fully established. Soil cover methods in these cases must last several years for soil protection and 

plant establishment.
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also be used to determine soil strength because it measures the amount of sediment that is 

detached from surface soils under various rainfall intensities (See Section 5.6.5, Infi ltration 

Rates). The USDA Natural Resources Conservation Service has developed a fi eld test for 

determining surface stability for water erosion (Inset 5.3). This method rates how well surface 

soil samples maintain their stability after being agitated in water.

5.6.4.2 Mitigating For Low Surface Strength

Apply Tackifi ers – Surface strength can be increased for up to a year or longer by applying 

tackifi ers by themselves, with hydromulches over bare soil surfaces, or to bond straw onto the 

site (See Section 10.3.2, Hydroseeding). These products strengthen the bonds between surface 

soil particles. Seeds applied with a tackifi er are held tightly to the soil surface, reducing the 

likelihood that seeds will be detached and moved.

Apply Mulch – Applying a long-fi ber mulch to the soil surface can increase the overall surface 

strength because of the interlocking nature of the fi bers (See Section 10.1.3, Mulches). The 

application of erosion mats can also increase surface strength.

5.6.5 Infi ltration Rates

Infi ltration is the ability of the soil surface to absorb water from rainfall, snowmelt, irrigation, 

or road drainage. A high infi ltration rate indicates that the soil surface can transmit high rates 

of water input from sources such as a thunderstorm; a low rate indicates that the surface has 

low capability of absorbing water. When infi ltration rates are lower than the rate of water input, 

runoff or overland fl ow will occur. Under these conditions, runoff can detach and transport soil 

particles, resulting in soil erosion and water quality problems. Overland fl ow can also remove 

sown seeds.

The size, abundance, and stability of soil surface pores determines the infi ltration rates of a soil. 

Large stable pores created by worms, insects, and root channels will absorb water quickly and 

Figure 5.46 – Soils low in clays and 

high in sands have very low surface 

strength. Not only are they prone to 

surface erosion, but even walking on 

them can leave the surface in a very 

disrupted condition.

Figure 5.47 – When precipitation 

exceeds infi ltration rates, water collects 

on the surface of the soil and begins 

to move downslope, causing erosion. 

On this site, litter and duff layers that 

typically protect the surface from rainfall 

impact have been removed, causing low 

infi ltration rates.
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A

B

C

Figure 5.48 – A portable “drop-forming” rainfall simulator developed by scientists at University 

of California Davis (Grismer and Hogan 2004) delivers water droplets through hundreds of 

needles (A). Pressure is increased or decreased to simulate rainstorm events. Droplets hit the 

surface of soil within a plot frame (B) and runoff water is collected at the bottom of the frame (C) 

to measure runoff rates and sediment production.

95

have high infi ltration rates, while surfaces that have been compacted, topsoil removed, or are 

low in organic matter will have poor infi ltration rates.

Under undisturbed conditions, infi ltration rates are high, especially where a litter and duff 

cover exists. When soil cover is removed, the impact from raindrops can seal the soil surface, 

creating a crust that will signifi cantly reduce infi ltration rates. Infi ltration rates are also reduced 

when the soil is compacted by heavy equipment traffi c.

5.6.5.1 Infi ltration Rates – How to Assess

The most accurate equipment for measuring infi ltration rates is the rainfall simulator. 

This method is an attempt to create rainstorms of diff erent intensities under controlled 

conditions and measure how the soil surface responds. Infi ltration rates are determined when 

runoff occurs. Runoff water is measured at the bottom of the plot to calculate runoff rates and 

sediment yields (Figure 5.48). While most rainfall simulators were developed for agricultural 

operations, several have been developed specifi cally for wildland conditions. These simulators 

were built for transportability and conservation of water, since construction sites are often 

in remote locations and often far from water sources. The “drop-forming” rainfall simulator, 

developed for wildland use, delivers rainfall at the drop size or impact velocity determined for 

the climate of the project site (Grismer and Hogan 2004).

Using the rainfall simulator in revegetation planning is expensive, yet it is an important tool 

and should not be discounted because of the cost. Specifi cally, rainfall simulation used to 

compare the eff ects of diff erent mitigating measures, such as mulches or tillage, on runoff and 

Figure 5.49 – When cut and fi ll slopes 

reach their angle of repose, non-cohesive 

soils move downslope at a continuous 

rate. The soil surface is constantly 

moving and never stable long enough 

for seeds to germinate and plants to 

become established. These slopes can 

remain barren for years. Soils that 

are high in sands and gravels are the 

most susceptible to dry ravel. In this 

picture, trees became established below 

rock outcrops, where the surface was 

protected from dry ravel.
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2:1 200 ft

Slope

V:H% SlopeDegrees

Hay/Straw MulchWood StrandRip/ChiselMechanical PlantingHand PlantingCat TrackTop SoilHand SeedlingBlown CompostHydromulch

Revegetation Methods

250 ft

100 ft

50 ft

50 ft 100 ft

200 65

1:1 100 45

1:1.5 66 34

1:2 50 25

1:3 33 18

1:5 20 11

2:1V:H

% SlopeDegrees

200 65

1:1 100 45

1:1.5 66 34

1:2 50 25

1:3 33 18

1:5 20 11

A B

Figure 5.50 – For engineering work, slope is generally expressed as the rise (V) over run (H). 

For slopes fl atter than 1:1, (45° or 100%), slope gradient is expressed as the ratio of one unit 

vertical to a number of units horizontal. For example a 1:2 slope gradient indicates that there 

is one unit rise to 2 units horizontal distance. For slopes steeper than 1:1, it is expressed as 

the number of units vertical to one unit horizontal (e.g., 2:1 indicates that there is a 2 unit rise 

to 1 unit horizontal distance). In general to avoid confusion, it is wise to notate the ratio by 

indicating the vertical (V) and horizontal (H), when defi ning gradient (e.g., 2V:1H). Range and 

forest sciences use % slope gradient to describe slope angle. Slope gradient refers to the number 

of feet elevation rise over 100 feet. A 66% slope gradient indicates that for every 100 feet, there is 

a 66 foot vertical distance rise. Slope gradient controls what type of revegetation treatments can 

be used (B). The steeper the slope gradient, the fewer tools are available. 

96

sediment production takes the guess work out of whether such measures are eff ective. This 

quantitative evaluation of erosion control methods might be essential in areas where water 

quality objectives are critical.

In most cases, infi ltration rates are broadly estimated under routine fi eld investigation by 

inference from site conditions. Infi ltration rates can be considered high when the soil surface 

has not been disturbed and has a high percentage of cover. With compaction and loss of 

surface cover, infi ltration rates are proportionally reduced. It is often assumed that construction 

activities that remove surface cover or disturb the topsoil will signifi cantly reduce infi ltration 

rates to levels that will create overland fl ow under most rainfall intensities.

5.6.5.2 Mitigating For Low Infi ltration Rates

Tillage – Infi ltration rates can be increased through soil tillage (See Section 10.1.2, Tillage) which 

reduces compaction, increases macro-pore space and creates surface roughness. Depending 

on the erosional characteristics of the site, the positive eff ects of tillage on infi ltration rates 

might only remain eff ective through a series of rainfall events.

Incorporating Organic Matter – Incorporating organic matter into the soil surface can 

increase the longevity of infi ltration rates created through tillage by forming stable 

macropores (See Section 10.1.5, Organic Matter Amendments). Unless macropores are 

interconnecting or continuous, however, they will not drain well (Claassen 2006). One method 

for creating continuous pores is to use long, slender organic material, such as shredded bark 

or hay. Compared to short organic materials, like wood chips, longer materials should increase 
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infi ltration rates. Incorporating higher quantities of organic matter will also increase porosity 

because of the potential of organic material to overlap and interconnect.

Surface Mulch – Applying surface mulch will reduce the eff ects of rainfall impact on surface 

sealing and reduce soil erosion rates (See Section 10.1.3, Mulches). It does not, however, 

necessarily increase infi ltration rates. Studies have shown that, while sediment yield can be 

less with the application of mulches, runoff rates are not necessarily reduced (Hogan and 

Grismer 2007).

Plant Cover – The best long-term way to increase infi ltration is to create conditions for a healthy 

vegetative cover. Good vegetative cover will produce soils with extensive root channels, 

aggregated soil particles, and good litter layers.

5.6.6 Slope Gradient

Slope angle or gradient is important in surface stability because it directly aff ects how soil 

particles will respond to erosional forces; the steeper the slope, the greater the erosional forces 

will act on the surface of the soil. Slope gradient is a dominant factor in water erosion and 

dry ravel erosional processes. In water erosion, the rate of soil loss and runoff from disturbed 

soil surfaces increases incrementally as slope gradient steepens. In dry ravel erosion, the 

surface remains stable until a specifi c slope gradient is reached, and then soil particles move 

downslope under the direct eff ects of gravity. This critical angle is called the angle of repose 

and it can be likened to the angle that accumulated sands make in an hourglass. Only noncohesive soils, such as sandy, gravelly, or silt textured soils, have an angle of repose; soils with 

signifi cant amounts of clays do not.

Dry ravel is occurring 24 hours a day. When you hear a piece of gravel or sand grain rolling down 

a cut slope, that is dry ravel. Not only does dry ravel create a constant supply of material to 

ditches, it also is impossible to revegetate unless the surface is stabilized. Seeds that germinate 

on steep, raveling slopes typically will not have enough time to put roots down deep enough 

to stabilize the surface before they roll downslope or are buried by soil particles rolling down 

from above. Figure 5.49 shows the angle of repose on a pumice sand parent material.

5.6.6.1 Slope Gradient – How to Assess

Slope gradient is quantifi ed in several ways, as shown in Figure 5.50. For road construction 

projects, slope is usually expressed as the rise (vertical distance) over run (horizontal distance). 

A 1:3 road cut, for example, defi nes a slope that rises 1 foot over every 3 feet of distance. 

Biologists, including range, forest, and soil scientists, use percent slope as a measure of slope 

angle. This is calculated by measuring the number of feet rise over a 100 foot length. Slope 

gradient as expressed in degrees is not commonly used.

Slope gradient can be measured in the fi eld using a handheld instrument called a clinometer. 

This equipment reads slope angle in percent slope and in degrees. Readings from a clinometer 

can be converted to rise over run notation using the chart in Figure 5.50. Road construction 

plans display the slope gradients for every cross-section corresponding to road station 

numbers (See Figure 3.3, in Section 3.2.3, Cross-Section View). Using these cross-sections, 

slope gradients can be identifi ed on the plan map by color coding the run:rise for cut and 

fi ll slopes. For instance, 1:1 cut and fi ll slopes might be highlighted red for areas of concern, 

while those areas with gradients 1:3 or less might be light green, favorable areas for mitigation 

work. This exercise can quickly identify areas where the highest risk for soil erosion and seed 

movement might occur.

Slope angle plays a key role in revegetation planning because of its potential limitation on the 

types of mitigation measures that can be implemented. Figure 5.50 shows which practices are 

generally limited to gentle slopes and which can be implemented on steep slopes. 

5.6.6.2 Mitigating for Steep Slope Gradients

Lengthen Cut or Fill Slopes – Slope gradient can be reduced by increasing the length of the 

disturbance. This will make the revegetation eff ort easier and more successful, but will increase 

the amount of area, or construction footprint, of the project.

Road planners consider many factors when they design the steepness of cuts and fi lls. A common 

design strategy is to create cut and fi ll slope gradients as steep as possible. This practice disturbs 

far less land, resulting in less area to revegetate. Because there is less exposed soil, the potential 
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C

D

E

A

B 30 ft

30 ft

60 ft

Horizontal Distance from Ditch

Vertical Distance from Ditch

Roadbed

Ditch

1:1

1V:2H

Natural ground 1V:2H

1V:1.5H

60 ft

Figure 5.51 – The trade–off between designing steep cuts that are diffi cult to revegetate or 

creating gentle slopes that disturb more area is demonstrated in this example. The centerline 

(A) of a new road intersects the 1V:2H natural ground (A to D). Fifteen horizontal feet of material 

must be excavated from the center of the road (A) to the ditch (B) to create the road bed. 

The resulting road cut will have varying lengths depending on how steep it is designed. A 1:1 cut 

slope will expose a 25 ft cut from the ditchline (B) to the top of the cut slope (C). A 1V:1.5H slope 

(B to D) will lengthen this exposure threefold to approximately 80 ft. A 1V:2H slope (B to E) is not 

achievable since it remains parallel to the natural ground slope.

98

for soil erosion is considerably reduced. Furthermore, there is a substantial cost savings with 

less excavation and revegetation work. Figure 5.51 gives an example of how increasing the 

steepness of a cut slope on a typical 1V:2H natural ground slope substantially decreases the 

length of disturbed soils.

The main drawback of steepening slopes, however, is that steeper slopes are much harder to 

revegetate, and the selection of revegetation practices available are reduced as the steepness 

of the slope increases (Figure 5.50). On sites with 1V:5H slopes or less, all revegetation practices 

are possible; on slopes approaching a 1:1 slope, the threshold of most revegetation practices 

has been reached, as well as the limit of what can be successfully revegetated. It is important 

to work with the design engineers early in the planning stages to consider the eff ects of slope 

gradient on meeting revegetation objectives.

Create Steep, Hardened Structures – Creating hardened structures or walls, such as retaining 

walls, crib walls, gabion walls, or log terrace design structures at the base of the slope will allow 

gentler slope gradients to be constructed above the structure. The drawback to hardened 

structures is that most are hard to revegetate.

5.6.7 Surface Roughness

Slopes that have roughened surfaces trap water during the initial stages of the runoff processes 

(Darboux and Huang 2005). Roughened surfaces consist of micro-basins that capture and store 

soil particles and seeds that have become detached in the erosional processes. Seeds that 

have been transported short distances into these depressions are often buried by sediments. 

Moderate seed covering from transported soil can enhance germination as long as the seeds 

are not buried too deeply. Micro-basins can also be relatively stable during the period for seed 

germination and seedling establishment. Surface roughness also reduces the eff ects of wind 

by reducing wind speed at the soil surface. However, as the micro-basins fi ll up with sediments, 

they become less eff ective in capturing sediments and seeds.
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Figure 5.52 – Surface roughness 

consists of micro-basins that are 

favorable to seed germination 

and early plant establishment.

B

A

Figure 5.53 – Surface erosion increases 

with distance downslope. On this site, 

sheet erosion turns to rill erosion at point 

B. Mitigation that shortens slope lengths 

to less than the distance between A to B 

will reduce rill erosion.

99

5.6.7.1 Surface Roughness – How to Assess

There are many methods of measuring surface roughness which include paint and paper 

profi ling, laser profi ling, and pin boards. A simple fi eld method for assessing surface roughness 

is using a cloth tape that conforms to the surface of the soil. In this method a tape is stretched 

a predetermined distance (e.g., 10 feet) and staked at both ends of the tape. Keeping the tape 

attached to one stake, the other end of the tape is released. Beginning at the staked end, the 

cloth tape is placed in contact with the soil surface and conforms to the micro-topography for 

the length of the tape. Tape distance is recorded where the end of the tape meets the end stake. 

The new distance is divided by the original distance to determine the surface area coeffi cient. 

The greater the distance between the two measurements, the greater the surface roughness.

5.6.7.2 Mitigating Measures For Smooth Soil Surfaces

Leave Surface Roughened – There is a tendency by many project engineers to “beautify” 

construction sites at the end of the project by smoothing soil surfaces. While basic landscape 

shaping is essential, the soil surface should be left as rough as possible. In many instances, 

leaving cut slopes “unfi nished” or in the “clearing and grubbing” stage provides excellent 

seed bed diversity and growing environment. The diversity of micro-habitats provides greater 

climatic and soil environments for seed germination.

Surface Imprinting – Imprinting the soil surface to create micro-relief has been shown to be 

eff ective in reducing runoff and soil erosion and increasing plant establishment (See Section 

10.1.2.4, Roughen Soil Surfaces).

Tillage – Tillage of the surface soil layers will leave the site in a roughened condition (See 

Section 10.1.2, Tillage). This practice has other benefi cial eff ects on the soil besides leaving the 

surface in a roughened state.
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Figure 5.54 – Structures that shorten the slope length can slow surface runoff , collect sediments 

and increase soil moisture. Typical treatments include: a) placement of fi ber rolls, logs, straw 

waddles, and compost berms; b) benches, steps, and trenches; c) willow waddles; and d) willow 

brush layers. Strategic placement of plants can take advantage of increased soil moisture by 

planting where roots can access the additional moisture. Most species do not respond well to 

being buried by sediment and should be planted above or below depositional areas (A and B). 

However, some species, such as willow, root where the stems are buried, and these species can 

be planted where sediments are expected to be deposited (C and D).

100

5.6.8 Slope Length

Another factor infl uencing soil erosion and seed transport is the length of slope. As the slope 

lengthens, so does the potential for transport of sediment and seeds. On very long slopes, 

the erosive force begins as sheet erosion at the top of the disturbance and often turns into rill 

erosion at the bottom of the slope (Figure 5.53).

5.6.8.1 Slope Length – How to Assess

Slope length can be measured in the fi eld or from road plans. The eff ects of slope length can be 

assessed by observing erosional features on existing disturbed areas. New or old disturbances 

can be used as references for critical slope lengths. As Figure 5.53 demonstrates, at some point 

downslope, erosional forces begin to cut rills into the surface soil. The distance downslope that 

this occurs can be considered the maximum length of slope for this site before severe erosion 

takes place. This distance will vary by the factors addressed in this section (soil cover, climate, 

slope gradient, surface strength, surface roughness, and infi ltration rates).

5.6.8.2 Mitigating Measures For Long Slopes

Install Barriers – Fiber rolls, straw waddles, downed wood, hay bales, silt fences, or compost 

berms can be laid on the surface as obstructions or barriers to reduce slope length. To be 

eff ective, they must be placed in contact with the soil and perpendicular to the slope gradient. 

Straw waddles, hay bales, and silt fences must be trenched into the soil surface.

Create Benches – The creation of slope breaks can reduce slope length. These breaks can be 

benches, steps, or trenches cut into the slope. The reduced gradient at these breaks slows the 

velocity of overland fl ow and collects sediments.

If either practice is applied in a long continuous line, they must be constructed on contour. 

If they are not placed correctly along the contour, water can collect and move along the 

structure, much like a channel, and eventually spill onto the slope below, creating rills and 

gullies. (The exception to this is the construction of live pole drains to redirect water off -site for 

slope stability [See Section 10.3.3.4, Live Fascines].) When placed properly along the contour, 

slope distances are shortened and the structures collect sediments and create areas for plant 

growth. Plants that are grown above obstructions or near the bottom edge of benches can 

take advantage of water and sediments that collect during rainstorms. Native vegetation can 

be incorporated into many of these designs to take advantage of increased soil moisture and 

sediment accumulation (Figure 5.54). The distance that these structures are placed apart from 

each other should be no greater than the critical distance observed on the site.
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Slumps

• moderate slope gradients

• circular failure movement

• cohesive soils

• deep soils

• slow moving

• steep slope gradients

• planar failure movement

• non-cohesive soils

• shallow 

• fast moving

Debris Slides

Figure 5.55 – Common landslides typically associated with road construction. Modifi ed after 

Varnes (1978) and Bedrossiand (1983).

101

5.7 SLOPE STABILITY

This discussion is directed to non-engineers to simplify and make accessible basic slope 

stability concepts that must be understood in developing revegetation strategies. It is by 

no means a substitute for professional engineering expertise. Technical references for slope 

stability are many (including Carson and Kirby 1972; Spangler and Handy 1973; Brunsden and 

Prior 1984; Denning and others 1994), to which we refer the reader for a comprehensive review 

of this subject. For a detailed evaluation of the role of vegetation in slope stability, the reader is 

referred to Gray and Leiser (1982).

Creating stable slopes is essential for establishing healthy plant communities, but the reverse 

is equally true – establishing native vegetation is critical for stabilizing slopes. This discussion 

comes from the latter perspective of how to create the most favorable environment for 

establishing vegetation and how this approach can be integrated into the overall strategy of 

slope stabilization. A vegetated slope adds stability to slopes by 1) holding the soil together 

through a network of root systems and 2) removing water from the soil, which is the primary 

driving force behind most landslides.

Slope stability is the resistance of natural or artifi cial slopes to fail through gravitational forces. 

The landforms resulting from slope failures are called landslides and they are described by their 

morphology, movement rates, patterns, and scale. This section will focus on two general types 

of landslides that are common to road cuts and fi lls – slumps and debris slides (Figure 5.55). 

Slumps typically occur on deep soils that are cohesive (rich in clays). They tend to be deep 

seated and slow moving. Viewed in profi le, the failure occurs in a circular motion, resulting in a 

series of tilted blocks and circular cracks. Debris slides are shallow, fast moving landslides that 

form on non-cohesive soils (e.g., sandy, gravelly). These landslides occur on steep slopes.

Water input is the driving force behind most slope stability problems encountered in road 

building projects. It comes as rainstorms, snowmelt, and often as diverted surface water from 

road drainage. As water increases in a potentially unstable slope, the added weight of the water 

in the soil plus the increased pressure of water in the pores (pore water pressure) eventually 

exceeds the strength of the soil, and the slope fails (Figure 5.56).

Increased water to a slope is especially a problem where a restrictive layer (a layer of soil 

that limits water movement) is close to the soil surface. As water moves through the surface 

horizon and encounters a restrictive layer, the water saturates the pores of the horizon above 

it, increasing the water pressure in the soil pores. The saturated horizon becomes heavier as 

the pores fi ll, and eventually the slope fails under the added weight of water and the increased 

pore water pressure.
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Figure 5.56 – Water pressure is 

great when soils are saturated 

(high pore water pressure). 

Slopes will release this pressure 

through channels (created by 

decomposing roots in this picture, 

or animal burrows, worm holes, 

and so on). When pressures 

become too great for the strength 

of the soil, slopes fail. This picture 

was taken 30 minutes before this 

road cut failed.

102

The faster water moves through soil, the less susceptible a slope is to failure. The measured 

rate at which water is transmitted through a soil mass is its permeability. When permeability 

is high, water quickly moves out of the soil pores, reducing the potential for increased pore 

water pressure or slope weight. When permeability is low, water slowly moves through soil 

and builds up in the soil pores. On gentle slopes, this is not a problem; as slope steepness 

increases, gravitational forces acting on the slope raise the potential for slope failure. Slope 

length is another factor important to water movement because the longer the slope, the 

greater the build up of water near the base of the slope. This phenomenon explains why many 

slope failures occur in the mid to lower portions of fi ll slopes.

Whether a slope fails or not is ultimately due to the strength of the soil. Soil strength is aff ected 

by the amount of clay present in the soil (the more clay, the greater the soil strength), how 

compacted the material is (the greater soil compaction, the more stable the soil), and the 

presence of roots (more roots are better). Often compacting soils takes priority over creating 

optimum soil for roots as methods for increasing soil strength. We suggest in the following 

discussion that the factors for increasing soil strength be considered together and integrated to 

produce the optimum stability, while at the same time creating the most favorable environment 

for native vegetation.

This section will discuss each of the following parameters as they relate to increasing slope 

stability through revegetation treatments:

 · Permeability,

 · Restrictive layers,

 · Water input,

 · Slope length,

 · Slope gradient, and

 · Soil strength.

5.7.1 Permeability

The rate at which a volume of water moves through soil material is its permeability (technically 

referred to as hydraulic conductivity). Soils that have moderate to high permeability rates tend to 

be more stable than those with low permeability rates. Where permeability is low, water fi lls the 

soil pores but does not drain quickly, adding additional weight to the slope and increasing the 

pore pressure. Both factors reduce the overall strength of slopes and increase the likelihood that 

slope movement will occur when other conditions are right.

Soils with large interconnecting pores have a higher permeability than soils with smaller pores 

that are less interconnecting. Soil textures that are well-graded (soils that have only one particle 
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size) typically have a higher permeability than poorly-graded soils (soils having a range of particle 

sizes from clays to small gravels). For example, poorly graded granitic soils have low permeability 

rates because the diff erent sized particles are neatly packed together, restricting the pathways 

for water fl ow. Well-graded soils, such as pure sands and gravels, have high permeability because 

pores are large and interconnecting. Compacted soils, on the other hand, often have low 

permeability rates because of the reduced or destroyed interconnecting macro-pores.

5.7.1.1 Permeability – How to Assess

Simple fi eld tests, such as percolation tests, historically utilized in assessing septic leach fi elds, 

can be used for determining permeability rates. A small hole is excavated and water is poured 

to a specifi ed depth. The time to drain the water from the pit is measured in inches per hour. 

These tests are run at diff erent soil depths to determine if permeability rates change. Results 

from percolation tests are subject to great variability. Nevertheless, they can indicate the 

relative permeability of diff erent soil types or diff erent soil disturbances.

Engineering laboratory tests for determining permeability include the constant head 

permeameter for coarse-grain soils. In this test, a soil sample is placed in a cylinder at the same 

density as the soils in the fi eld. Water is introduced and allowed to saturate the sample. A constant 

water elevation, or head, is maintained as the water fl ows through the soil. The volume of water 

passing through the sample is collected and this provides a direct measurement of the fl ow rate 

per unit of time. The test can be repeated at various densities to determine the corresponding 

permeability. The test can also be repeated for various additions of organic amendments and 

compaction levels to determine the eff ects of these treatments on permeability. Consult a 

soil lab for how to collect and submit samples for these tests. Where testing is not feasible, 

engineering and soil texts can give ranges for expected permeability based upon the soil 

gradation and classifi cation. A fi eld assessment can also give some indication of permeability 

rates. Subsoils or soils lacking organic matter that have a range of soil particle sizes, from clays 

through small gravels, have a propensity for low permeability rates, especially when they are 

compacted (See Section 5.3.3.1, Soil Structure – How to Assess).

5.7.1.2 Mitigating For Low Permeability

Tillage – Loosening compacted soil through tillage practices (See Section 10.1.2, Tillage) 

increases permeability by creating large fractures or pathways for water to fl ow. However, tilled 

soils often return to near-original permeabilities as the soils settle over time.

Organic Amendments – Long-fi bered organic matter tilled deeply into the soil will increase 

the infi ltration and permeability of the soil because larger, interconnecting pore spaces are 

created (See Section 10.1.5, Organic Matter Amendments). Several studies evaluating the 

incorporation of unscreened yard waste suggests that an optimum rate of organic matter 

additions for increasing infi ltration and improving soil structure is approximately 25% compost 

to soil volume (Claassen 2006). In addition, incorporating organic matter can also increase slope 

stability because amended soils are lighter in weight than non-amended soils; mineral soils 

can weigh 10 to 20 times more than soils amended with 25% organic matter. The reduced soil 

weight lowers the driving forces that create unstable slopes. Additions of organic matter with 

high C:N ratios can limit the establishment of vegetation. Using composted organic matter will 

reduce the length of time that nitrogen is unavailable.

5.7.2 Restrictive Layer

A restrictive layer is any soil horizon or stratum (including unfractured bedrock) that has very low 

permeability. As water fl ows through a surface horizon with good permeability and encounters 

a restrictive layer, the rate of downward vertical water movement slows and water builds up 

in the pores of the upper layer. Since the permeability of the surface layer is higher than the 

restrictive layer, water moves laterally downslope above the contact. Slope failure occurs when 

the pores in the soils above the restrictive layer become saturated with water to a point where 

the pore water pressure and soil weight exceeds the soil strength. Failure occurs within the soils 

above the restrictive layer. The depth of slope failure depends on the thickness of the surface 

layer. On slopes where the restrictive layer is near the surface, slope failure, if it occurs, will be 

shallow (Figure 5.57). Where the contact is deeper, the soil movement will be more extensive. 

The types of landslides that occur with restrictive layers are debris slides.
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5.7.2.1 Restrictive Layer – How to Assess

Restrictive layers in natural settings can be inferred by the presence of seeps and springs. These 

features occur most often at the point where a restrictive layer is intercepted or exposed to the 

surface. These can be intermittent features that are observed in the winter or spring that dry 

up in the fall or winter. The vegetation around permanent and temporary seeps and springs 

is typically composed of water-loving species, such as sedges (Carex spp.) and rushes (Juncus

spp.). Figure 5.58 shows how a seep is created when a cut slope intersects a restrictive layer.

On construction sites, restrictive layers can be created by placing a loose soil over a highly 

compacted subsoil. These layers can be identifi ed in the fi eld by determining soil strength 

using a soil penetrometer or shovel to fi nd compacted or dense soils (See Section 5.3.3, Soil 

Structure). This layer is then assessed for the approximate amounts of silt and clay using the 

fi eld texturing method. Dense or compacted soil layers that are high in silts and clays are likely 

to be very restrictive to water movement. Field permeability tests can be used to determine the 

rates of water fl ow (See Section 5.7.1.1, Permeability – How to Assess). Often restrictive layers 

are not observed until after construction when they manifest themselves as intermittent seeps 

or wet areas in cut and fi ll slopes. Geotechnical investigation will determine if these features 

are due to shallow water movement associated with restrictive layers or interception of deeper 

subsurface water interception.

5.7.2.2 Mitigating For Restrictive Layers

Tillage – If restrictive layers are within several feet of the soil surface, site treatments that break 

up portions of this layer can increase the permeability and increase stability. Site treatments 

that accomplish this are bucket tillage, deep ripping, spading, and fi ll cut (benching and 

backfi lling) which are discussed in Section 10.1.2, Tillage. The drawback to tillage is that it will 

reduce soil strength in the short term until roots occupy the soil and increase soil strength. 

Temporary irrigation systems have been installed on sites where quick establishment of 

Seeps Ground Water

Restrictive Layer

Figure 5.58 – Groundwater 

moves downslope above 

restrictive soil layers. Seeps 

are seen in road cuts where 

the restrictive layer is exposed. 

Increased soil water that occurs 

above restrictive layers can 

increase slope instability.

Figure 5.57 – In this 

photograph, a restrictive 

layer is very close to the 

soil surface. During a 

rain storm, water moved 

through the shallow soil 

layer and encountered 

a restrictive layer. Water 

then moved downslope, 

building up pressure, until 

the increased pore pressure 

and soil weight exceeded the 

strength of the soil to resist 

these forces. At this point, 

mid to lower slopes failed.
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grass cover during summer and fall months is essential for slope stabilization prior to winter 

precipitation (Hogan 2007).

Organic Amendments – Where possible, the incorporation of organic matter will help keep 

the restrictive layer from returning to its original soil density and allow more time for roots to 

become established (See Section 10.1.5, Organic Matter Amendments). As mentioned above, 

soil strength might be reduced until vegetation has become established, but the negative 

eff ects of reduced soil strength could be off set by the increased permeability and reduced soil 

weight of the organic amendments.

Live Pole Drains – Live pole drains are constructed to intercept water from seepage areas and 

remove it through a system of interconnecting willow bundles (which act as a drain) to more 

stable areas, such as draws, ditches, or other waterways (See Section 10.3.3.4, Live Fascines). The 

interception and fl ow of water encourages the establishment and growth of willow cuttings 

along the length of the live pole drain.

5.7.3 Water Input

Water, which is the driving force behind most landslides, comes through rainfall, groundwater 

fl ow, snow melt, or diverted from other areas through road drainage. Landslides often occur 

after a series of strong winter storms have delivered a high amount of rainfall over a short 

period of time. Under these conditions, soils have not had suffi cient time to drain before the 

next storms arrive. When warm storms bring rain to slopes with snow pack (called “rain on 

snow events”), water from rain plus melting snows is very high, increasing the probability for 

the occurrence of landslides on potentially unstable sites. Landslides can occur where water 

from road ditches or other road features drain water onto marginally unstable slopes. Major 

site factors that aff ect water input are: 1) rainfall duration and intensity, 2) rain-on-snow events, 

and 3) road drainage.

5.7.3.1 Water Input – How to Assess

See discussions under Section 5.2, Water Input for how to assess water input.

5.7.3.2 Mitigating For High Water Input

Proper Surface Drainage – Increased water is the driving force behind slumps and debris 

slides. Designing proper water drainage is probably the most important measure to implement 

for slope stability (Gedney and Weber 1978). Where road water is inadvertently routed into 

potentially unstable areas, there is a greater potential for slope failure (Fredricksen and Harr 

1981). Road projects are designed to move storm water away from or out of unstable slopes as 

quickly as possible through road and slope drainage structures.

Species Selection – Select species that have adapted to wet soils. These include sedges 

(Carex spp.), rushes (Juncus spp.), bulrushes (Scirpus spp.), willows (Salix spp.), cottonwoods 

(Populus spp.), and cedars (Thuja spp. and Chamaecyparis spp. ). Since each species has a unique 

way, or strategy, of modifying the moisture regime of a site, planting a mixture of species is a 

way of assuring that all strategies are represented on the site. For instance, willows establish 

quickly and can draw large quantities of moisture from the soil, but only when the willows 

have leaves. Cedars, on the other hand, are slower to establish, but longer lived. They can 

withdraw moisture from the soil during the winter months, unlike deciduous species. When 

they are well established, they will intercept large amounts of water in the crowns, preventing 

precipitation from reaching the soil. Trees have a great ability to signifi cantly deplete moisture 

at considerable depths (Gray and Leiser 1982). Wetland species, such as rushes and sedges, 

unlike many trees and shrub species, are not limited by saturated soils. They thrive and draw 

down moisture where other species will perish.

Live Pole Drains – The live pole drain (Polster 1997) is a biotechnical engineering technique 

where continuous willow bundles (See Section 10.3.3.4, Live Fascines) are placed across a slope, 

much like an open drain, to redirect water to a more stable area (channels, draws, and so on). 

Where small slump failures have occurred during or after construction, live pole drains can 

be installed to increase slope drainage, add root strength, and remove soil moisture from the 

slide mass.
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Figure 5.59 – Slumps are characterized by scarps, cracks, and benches. Water collects on 

the benches and in the cracks where it is transmitted into the slide mass, creating continued 

instability. Water can be removed through a series of hand-dug surface ditches. Using the 

cracks as guides for the location of ditches, they are fi lled in with soil and dug wide enough for 

a willow fascine (See Section 10.3.3.4, Live Fascines) to be placed in the bottom (A). Called “live 

pole drains” (Polster 1997), these structures not only quickly move surface water off the slide to 

more stable areas, but the willow cuttings in the fascines, encouraged by the presence of high 

soil moisture, grow into dense vegetation (B) that stabilize the slide through the deep rooting 

and dewatering.

A B

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5.7.4 Slope Length

Slope length is important in stability because the longer the slope, the more water can 

concentrate in the lower portion of the slope. Increased water will increase pore water pressure 

and soil weights, decreasing the stability of the mid to lower sections of long slopes. This is one 

reason why slumps are often observed in the mid to lower slope positions of longer fi ll slopes.

5.7.4.1 Slope Length – How to Assess

Slope length can be obtained from road plans or measured directly in the fi eld using a tape.

5.7.4.2 Mitigating For Long Slopes

Live Pole Drains – Using live pole drains (discussed in the previous section), shortens the 

distance water is transmitted through the hill slope by intercepting surface and subsurface 

water in ditches at frequent slope intervals. Captured water is transmitted downslope through 

a system of continuous fascines to a stable channel (Figure 5.59).

Create Benches – Another method of reducing slope length can be the creation of a slope 

break. These are benches, steps, or trenches cut into the slope. The reduced gradient at these 

breaks slows the velocity of overland fl ow and collects sediments. However, unless the water is 

directed off the slope, total water input to the slope is not reduced.

5.7.5 Slope Gradient

As slope gradient increases, the destabilizing gravitational forces acting on the slope become 

greater. On a level surface, the gravitational force stabilizes the soil mass. As the slope gradient 

increases, the amount of force available to resist sliding along the failure surface decreases.

5.7.5.1 Slope Gradient – How to Assess

Assessing slope gradient is discussed in Section 5.6.6.1, Slope Gradient – How to Assess.

5.7.5.2 Mitigating For Steep Slopes

Mitigating measures for steep slopes are discussed in Section 5.6.6.2, Mitigating for Steep 

Slope Gradients.
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Figure 5.60 – Plant roots and 

stems increase slope stability 

by (A) reinforcing the surface 

horizon through a matrix of 

roots, (B) anchoring surface 

horizons to rock or subsoils, 

and (C) stems supporting the 

soil upslope.

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5.7.6 Soil Strength

Soil strength (technically referred to as shear strength) is the characteristic of soil particles to 

resist downslope forces. The major physical factors contributing to increased soil strength are: 

1) reduced porosity (compacted soils), 2) greater range of particle sizes (poorly graded soils), 

3) greater angularity of the soil particles, 4) greater surface roughness, and 5) presence of silts 

and clays that add cohesive strength (Hall and others 1994). 

The biological components contributing to increased soil strength are the: 1) matrix of roots 

that reinforce the surface horizon, 2) roots that anchor an unstable soil mantle to stable 

subsoils or rock, and 3) stems (e.g., trunks of trees) that add support to the soil immediately 

uphill (Hall and others 1994) (Figure 5.60). The physical factors, unfortunately, do not always 

support the biological factors. For example, porosity should be of particular interest to the 

revegetation specialist. From an engineering standpoint, low porosity soils have greater soil 

strength than soils with high porosity because soil particles are packed closer together and 

interlock. Reducing porosity is accomplished through various methods of compaction. From 

a vegetation standpoint, however, this practice is very limiting to plant establishment and 

vegetative growth (See Section 5.3.3, Soil Structure). Balancing the needs of creating a healthy 

soil for optimum vegetation while still maintaining slope stability until established vegetation 

adds root strength to the soil is a challenge to engineers and revegetation specialists. Creating 

soils with high porosity will decrease soil strength in the short term. However, if this practice 

increases the productivity of the site, the long-term result is often a net increase in soil strength 

(Gray and Leiser 1982).

The growth habits of native species can greatly infl uence slope stability because each has a 

unique rooting pattern and root tensile strength. For instance, grass roots are very fi brous and 

abundant in the surface horizon, adding surface stability when the grass cover is high. Grass 

and forb roots, however, are not as strong and do not penetrate as deeply into the soil as tree 

roots, and add little strength at deeper depths (Gray and Leiser 1982). The roots of shrub and 

tree species, on the other hand, are long and deep rooted, with relatively high tensile strength 

(Gray and Leiser 1982). The main advantage of these species is the long vertical roots (taproots) 

that can cross failure planes and bind the soil strata together.
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5.7.6.1 Soil Strength – How to Assess

While the revegetation specialist will probably never perform an engineering test for soil 

strength, it is important to understand that there are routine assessment methods used for this 

determination. These tests are especially important to consider if the revegetation specialist 

is advising that soils on potentially unstable sites be deeply tilled or amended with organic 

matter, since these practices can reduce soil strength until vegetation is established.

A common method engineers use to estimate soil strength is to correlate soil classifi cation 

(from sieve analysis and the characteristics of clay particles) with published literature values. 

Shear vanes or cone penetrometers are good methods to approximate the strength of fi negrained soils in the fi eld. Published research is used to correlate fi eld instrument readings with 

laboratory shear strength test results.

The triaxial shear test is a more precise laboratory method to determine shear strength of 

soils. In this test, a long cylinder of the soil is placed in a latex membrane and submerged in 

a clear plastic cylinder fi lled with water. A vertical pressure is applied to the cylinder at a slow 

rate until the soil sample shears. Very sensitive strain gauges measure the soil displacement, 

applied forces, and any pore water pressures that develop. Various water pressures are applied 

to the cylinder to simulate the confi ning pressure of soil depth (Brunsden and Prior 1984). 

This test can be used to determine the shear strength of soils that have been amended with 

organic materials.

5.7.6.2 Mitigating For Low Soil Strength

Biotechnical Engineering Techniques – Many biotechnical slope stabilization techniques use 

vegetative cuttings from willows or other easy-to-root species to structurally reinforce the soil. 

As these materials root, they add further stabilization to the slopes through interconnecting root 

systems and soil moisture withdrawal. These practices include stake planting, pole planting, 

joint planting, brush layers, and branch packing (See Section 10.3.3, Installing Cuttings).

Shrub and Tree Seedlings – On drier sites, where willow cuttings are less likely to survive and 

grow, shrub and tree seedlings can be used. While these species are slower growing, they 

usually have deeper root systems and persist longer once they are established. Grass and forb 

species can quickly establish on drier sites, but soil strength is limited to the surface of the soil 

profi le where the roots are most abundant. On potentially unstable sites, grasses should be 

grown between shrub and tree seedlings to add soil strength to the surface soil while tree and 

shrub species become established. On dry sites, however, grasses must be excluded around 

seedlings or vegetative cuttings until they have become established. Because of the steep, 

shallow nature of many of these sites, planting seedlings is not always practical or successful. 

Hydroseeding or hand sowing, covered by a surface mulch that will protect the surface from 

erosion for several years while the shrubs become established, should be considered.

Soil Improvement – Improving soil productivity will thereby increase the density of roots and 

increase slope stability (Hall and others 1994). Mitigating measures that improve water storage, 

organic matter, and nutrients should, with time, increase slope stability. Some practices, such 

as soil tillage, reduce soil strength in the short-term. However, once plants have become 

Figure 5.61 – This debris slide 

(noted by its shallow, steep 

appearance) took place two 

years after construction when 

the grass and forbs were fully 

established. Establishing shrub 

species, rather than grass and 

forb species, to steep, potentially 

unstable slopes would be better 

for long term stability because 

shrub species are deeper 

rooting and have higher root 

tensile strength.
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established, more roots occupy the soil and slope stability is increased. Tillage should be 

integrated with practices that quickly reestablish vegetation to assure that slope stability is 

not compromised in the short term. On slopes where root strength is critical for stability in the 

fi rst year after construction, irrigation might be considered in order to quickly establish a dense 

vegetation cover.

5.8 WEEDS

Weeds are unwanted vegetation on a construction site or surrounding areas before, during or 

after revegetation. Roadsides can be major conduits for weeds, including invasive, noxious, 

introduced, and exotic species problematic not only for roadside ecology, but also for the 

general ecosystem health of surrounding lands and economic well-being of adjacent farmers, 

ranchers, gardeners, and other land managers. A poorly revegetated roadside can contribute 

to the spread of weeds and detract from environmental health. On the other hand, a good 

native revegetation plan can benefi t surrounding environments. The best management will 

focus not on fi ghting weeds, but on establishing healthy, weed-resistant communities of 

desirable vegetation.

For the revegetation specialist, the term “weeds” denotes any species (usually non-native) that 

is limiting to successful revegetation with native plants due to increased competition. Weeds 

may be listed on federal, state, or local lists as noxious weeds or invasive species. The exact list 

of weed species will generally be determined on a project-by-project basis. 

Categories of weeds include:

 · Invasive,

 · Noxious,

 · Competing,

 · Introduced, and

 · Exotic.

The potential for weed species to become established after construction is a function of two 

site parameters:

1) The growing environment. Are areas within the construction project favorable 

environments for weed establishment? These areas are often highly disturbed sites 

with bare soils.

2) Weed sources. Are there existing weed populations and seed sources on the site prior 

to construction, or is there a potential that weeds can be brought into the site during 

construction? Sources of weeds are existing seed banks, infested adjacent lands, or 

transported from infested areas by vehicles.

Construction projects should consider the development of a weed management strategy that 

addresses how to control the plant environment and the plant source in the early stages of 

planning. Ideally, this strategy should be implemented 2-3 years prior to actual construction, 

Inset 5.4 – General Advice for Managing Weeds (Sheley 2005)

 · The goal should be to develop weed resistant plant communities.

· The first priority should be to protect uninfested areas and areas that have desirable 

species available to colonize the site once the weed species are treated.

 · Establish not only early seral species, but a diversity of mid-and late-seral species fi lling 

ecological niches in order to prevent invasion of weeds.

 · Any prevention program should be comprehensive and complete.

 · There are no silver bullets. Managing weeds is time consuming, complex, and an 

iterative process. Try things and then adapt.

 · Early detection and rapid response is critical to preventing weed infestation. Develop 

a systematic, thoughtful detection strategy early in the planning phases. Look for new 

patches or problematic sources before they spread, and treat appropriately.
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continued through the construction phase, and up to 3 years post-construction. Depending 

on the severity of undesirable vegetation, additional long term treatments may be needed. 

Treatment of material sources and spoils areas should also be included in planning. 

5.8.1 Growing Environment For Weeds

The strategy for keeping weeds out of a project area should focus ultimately on developing a 

growing environment that encourages healthy native plant communities over weedy species. 

The presence or introduction of weeds into an area does not necessarily mean that these 

species will become established or spread. There must fi rst be an opening or space in the native 

plant community for the plants to grow. These conditions almost always occur in a disturbed 

area, in openings where native plants and soil have been removed or disrupted. Secondly, the 

disturbed environment must be favorable for the undesirable species to take hold and thrive. 

This requires that the soils and climate be optimal for the environmental needs of the species. 

Third, the weed species must have an advantage over native species. If the weeds are more 

resilient or robust in their growth habits in both adjacent lands and disturbed sites (that is, cuts 

and fi lls) then they are more likely to become established.

5.8.1.1 Growing Environment For Weeds – How to Assess

Each undesirable plant species has unique environmental needs which must be considered 

when assessing if a site environment is conducive to invasion by that species. The following are 

site factors to evaluate:

 · Bare soil surface – Most weed seeds need bare soil to germinate and become 

established. Protocols for monitoring bare soil are presented in Chapter 12.

 · Soil nitrogen – Many weeds out-compete native plants on soils that are high in 

nitrogen because they are more adapted to utilizing nitrogen during early plant 

establishment. Unless fertilizers are added to the site, soil nitrogen levels are typically 

low after construction.

 · Light – Weeds tend to require full or partial sunlight to thrive (Penny and Neal 2003).

 · Soil quality – The potential that a healthy native plant community can be established 

after disturbance reduces the possibility for weed invasion. Optimum native plant 

establishment is dependent on the condition of the soil and climate. A compacted site, 

lacking topsoil and organic matter, is poor for establishing a native plant community 

which would ultimately keep weeds from invading. Unlike perennial plants, the roots of 

most annual weed species occur in the surface layer (Jackson and others 1988; Claassen 

and others 1995) and do not require deeper soils to survive and grow. Annual species 

therefore will have an advantage over perennials on compacted soils or shallow soils.

Based on the assessment of these factors, risk maps can be developed showing: 1) the location of 

weed sources in or adjacent to the project, and 2) the optimum habitats for each weed species. 

The combination of these maps will show the high risk areas and can be used to develop a 

strategy for weed control.

Figure 5.62– Invasive plants 

such as Himalayan blackberry 

[Rubus discolor (Weihe & Nees)] 

(left) and Scotch broom [Cytisus 

scoparius (L.) Link] (right) 

are aggressive colonizers of 

disturbed sites such as roadsides 

(Photo by Sally Long, Dorena 

Genetic Resource Center.)
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Inset 5.5 – Prevention: Working Groups to Establish Weed-Resistant 

Plant Communities

(adapted after Sheley 2005)

In order to develop weed-resistant plant communities, representatives of working groups 

that best fi t the site are necessary. Working groups have the following components:

 · Annual forb component

 · Taprooted forb component

 · Bunchgrass component

 · Rhizomatous perennial grass component

These species occupy multiple niches and can prevent the invasion of weed species. 

For more information, see Chapter 6.

5.8.1.2 Reducing or Eliminating Weed Growing Environments

Protect Uninfested Ground and Minimize Ground Disturbances – Reducing the footprint of 

the project results in less area being disturbed and exposed to possible weed invasion.

Develop Optimum Environments for Quick Native Plant Recovery – Developing mitigating 

measures that create an optimum environment for native plant recovery will limit the 

establishment and spread of weeds (Sheley 2005). Site factors that restrict downward root 

growth of native perennial plant roots (e.g., compacted soil) give the advantage to weed 

species. Treat seed-bed preparation as an investment.

Retain Shade – To reduce the vigor of undesirable plants, retain as much shade as possible.

Apply Mulch – A mulch can be applied to the surface of a disturbed soil to create a poor 

germination environment for weed seeds (See Section 10.1.3, Mulches). The mulch should have 

high void spaces (typical of long-fi ber mulch materials) and low water-holding capacity. These 

characteristics are unfavorable for seed germination. The deeper the mulch, the greater the 

control of weed establishment. Depending on the weed species, 2 to 4 inches of mulch are 

required to eff ectively control the establishment of many weed species (Pellett and Heleba 

1995; Ozores-Hampton 1998; Ozores-Hampton and others 2002; Penny and Neal 2003).

Oversow Native Seed Mix – Sowing native seeds at high rates will “fl ood” bare soil with the 

seeds of desirable species, reducing the “germination sites” where weed species can become 

established. The objective of this strategy is to fi ll the voids fi rst with desirable species to crowd 

out unwanted species (See Section 10.3.1, Seeding).

Establish Desirable Non-Native Plants If Establishment of Natives Is Not Feasible – Due 

to surrounding site limitations, project parameters, timelines, or other circumstances, using 

locally adapted native plant materials may not always be possible. For example, if the project 

is surrounded largely or entirely by contiguous populations of cultivars, using locally adapted 

plant materials may largely be a waste. If the surrounding area is primarily native species, careful 

selection of cultivars should be considered. Many cultivar species, both native and introduced, 

have the potential to cross with their locally adapted native equivalent genera (See Section 

6.4.1, Ensure Local Adaptation and Maintain Genetic Diversity).

Avoid Applying Nitrogen Fertilizers in First Year – High rates of nitrogen fertilizers can 

encourage the growth of weedy annuals at the expense of the establishment and growth 

patterns of native perennials (McLendon and Redente 1992; Claassen and Marler 1998), 

whereas perennial grasses have a competitive advantage at lower nitrogen levels (Welker and 

others 1991). Application rates of up to 108 lb/ac N(121 kg/ha N) have been shown to promote 

the establishment of introduced grasses over less competitive native grasses (DePuit and 

Coenenberg 1979). High rates of nitrogen fertilizers can also aff ect revegetation eff orts by 

decreasing species richness and increasing the presence of non-native species (Munshower 

1994; Wedin and Tilman 1996).When nitrogen fertilizer is applied at seeding, root systems of 

native perennials establish in the upper portion of the soil. The decrease in deep roots gives 

the annual weed species a competitive growth advantage (Claassen and others 1995). Limiting 

the amount of nitrogen fertilizer used the fi rst year (during vegetation establishment) will help 

force the roots of perennials deeper into the soil where there is more moisture. The deeper root 
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system increases the competitive advantage of the native perennials over the annual weeds. 

This strategy, however, does not preclude the need for fertilization. It might be that fertilizers 

are not applied until a year after sowing, when the native plants have become established 

(See Section 10.1.1, Fertilizers). 

Apply High C:N Materials to High Nitrogen Sites – If soils are high in nitrogen, applying a 

high C:N material (e.g., wood products or hay) to the surface of the soil, or mixed into the soil, 

is another strategy to reduce the amount of available nitrogen for annual weed growth (REAP 

1991; St John 1999). Over time, the organic material will break down and release nitrogen for 

uptake by perennials.

5.8.2 Weed Sources

Weed species come from sources already on the site, or are brought into the site from outside 

sources. They are typically propagated from transported seeds. In rare cases, they can arrive 

as live plants and plant parts (e.g., blackberry stems). Reproductive materials are brought in 

on construction equipment, cars and trucks, shoes and socks. The source of these materials 

are often sand, gravel, and rock used for road construction materials. All too often, weeds 

arrive during the revegetation eff orts in contaminated mulches, topsoil, and uncertifi ed 

seed sources.

5.8.2.1 Weed Sources – How to Assess

During the early phase of planning, vegetation surveys, noxious weed inventories (conducted 

during the environmental assessment), and topsoil surveys will locate and identify weeds. 

From these surveys, a noxious weed map can be developed which can then be used in the 

development of a weed control strategy for the project site. County weed boards and county 

and state road management staff may also be a source of information, as they track and 

treat weeds.

The backbone of a weed control strategy is a thorough understanding of the physiology and 

ecology of the weed species. The questions to answer for each potential species include:

 · How do they propagate?

 · How do they spread?

 · What is their rate of spread?

 · What are their growth habits during the year?

 · How long do they survive?

 · What is their life cycle?

 · Are they annual, biennial, or perennial?

 · Is there potential for an ecological progression to more aggressive species (e.g., 

cheatgrass infestations may give rise to more aggressive species such as knapweed)?

 · What are the control methods and how eff ective are they?

 · What are their environmental needs?

 · What are their soil type preferences?

 · What are their nitrogen needs?

 · What sort of environment is needed for seed establishment (e.g., bare soil)?

 · What are their climate preferences?

 · Do they grow well in direct sunlight or do they prefer shade? 

5.8.2.2 Preventing the Introduction of Weed Sources

Control of weeds falls into two categories – prevention and treatment. Preventing the 

introduction of a weed species is always the preferred strategy because it is easier and more 

economical to prevent the introduction of a weed species than to control or eliminate it once 

it has become established. If prevention fails, however, and weeds have become established, 

then treatment strategies should be implemented to contain and eliminate the problem.
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Identify and Monitor Weed Populations – Locate weed populations early in the planning 

phases. Early detection and rapid response is critical to preventing weed infestation. 

Develop a systematic detection strategy. Identify and treat new patches before they spread 

(Sheley 2005).

Clean Equipment When Leaving Weed-Infested Sites – When equipment or vehicles have 

been used in an area where weed species are present, it is important to thoroughly wash the 

tires, wheel wells, and chassis to eliminate the possibility that weed seeds are spread when the 

equipment is transported to another site. Portable wash stations may be set up for treating 

newly arriving equipment.

Clean Hydroseeding Tanks, Range Drills, Other Seed Delivery Systems – Unless equipment 

is brand new, seed delivery systems have been used at other projects and can contain plant 

species that are not wanted on the next site. A thorough cleaning and inspection of this 

equipment is essential in eliminating the potential introduction of weeds. Hydroseeding tanks 

must be washed out and range drills air-blown before entering the project site.

Know the Quality of Seed Sources – Native grass and forb seed sources can contain weed seeds 

that were harvested along with the native seeds. The quantity of undesirable species present 

in propagated seed sources is dependent on the weed control practices and seed cleaning 

technology implemented by the seed producer. Because of the possibility of contamination of 

native seeds with weed seeds, seed testing must be conducted for all seeds that are purchased 

or procured. Purity tests will reveal the contaminants in a seedlot, including weed seeds, other 

plant seeds, and inert material. Testing is conducted through certifi ed seed labs according to 

the Association of Seed Technologists Association (AOSTA) standards. Seed labs test for the 

presence of state-listed noxious weeds and other crop species. It is important to check state 

and federal lists to determine if any local weed species should be added to the testing list. Do 

not buy seeds with an undesirable or untested weed component.

Know Quality of Mulches – Buy mulch that is free of weed seeds. Hay and straw mulches are of 

special concern. Some states certify hay or straw as “weed-free.” This means that the material 

is free of noxious weeds. It does not mean that the material is free of seeds, however. Some 

straw comes from the stubble left after a seed harvest of native grasses, which often includes 

unharvested seeds. These seeds are viable and will establish into plants when the straw is 

Figure 5.63 – Hay bales 

often contain seeds that will 

germinate on the site. Prior 

to purchasing hay, fi nd out 

what species were grown 

in the fi eld. Some states 

have certifi ed weed-free 

programs. However, “weedfree” does not mean the 

hay will be seedless. Some 

of these seeds might not be 

desired in your project area.
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A

B

Figure 5.64 – Know the origin 

and quality of the topsoil. 

Topsoil sources contain seeds of 

the species that grew on them 

prior to salvage. In this picture, 

the topsoil pile on the right (B) 

was salvaged from a nearby 

pasture and the pile on the left 

(A) from an undisturbed native 

forest site. The pasture topsoil 

pile revegetated quickly (within 

3 months after stockpiling) 

because of the abundance of 

non-native seeds in the soil. 

The forest topsoil revegetated 

slower because there were 

less seeds. Application of the 

pasture topsoil (B) resulted in a 

site dominated by introduced 

pasture plant species.

A

B

Figure 5.64 – Know the origin 

and quality of the topsoil. 

Topsoil sources contain seeds of 

the species that grew on them 

prior to salvage. In this picture, 

the topsoil pile on the right (B) 

was salvaged from a nearby 

pasture and the pile on the left 

(A) from an undisturbed native 

forest site. The pasture topsoil 

pile revegetated quickly (within 

3 months after stockpiling) 

because of the abundance of 

non-native seeds in the soil. 

The forest topsoil revegetated 

slower because there were 

fewer seeds. Application of the 

pasture topsoil (B) resulted in a 

site dominated by introduced 

pasture plant species.

114

applied. If this is the origin of the straw, it is important to obtain the species and seed zone of 

the seed crop to determine if this material is appropriate for your project. A site visit prior to 

hay or straw cutting is a good way to assess if there are seeds of weed species in the material 

(Figure 5.63).

Know Quality of Compost Sources – Compost sources are not always free of weeds, especially 

if the materials were not composted properly. Compost temperatures must reach lethal 

temperatures and remain there long enough for plant seeds to be rendered nonviable. Fresh, 

moist compost piles, where temperatures are maintained between 140 to 160 °F for at least 

several days, will kill most pathogens and weed seeds (Epstein 1997; Daugovish and others 

2006). When obtaining compost, make sure that the supplier complies with standards that 

meet the time-temperature requirements to ensure destruction of weed seeds. Testing and 

analysis information is available from the United States Composting Council (See Section 10.1.5, 

Organic Matter Amendments).

Inspect Gravel, Sand, and Rock Sources – Prior to acquiring road building materials such as 

sand, gravel, and rock, determine if this material comes from a source that is free of undesirable 

weeds. A plant survey of the source area will identify whether the material is suitable.

Inspect Haul Routes and Waste Areas – Treat or avoid infested areas.

Know the Quality of the Topsoil – The topsoil survey should identify areas of weeds (See 

Section 5.11.1, Survey Topsoil). These areas should be mapped out and avoided when the 

topsoil is salvaged. If the topsoil is purchased, the piles should be inspected prior to approval 

(Figure 5.64).

Do Not Store Sand, Gravel, Rock or Topsoil Near Weed Populations – Inspect the areas 

where topsoil, gravel, rock, sand, or other materials to be used on the construction project will 

be stockpiled. If there are weeds nearby, it is very likely that seeds will end up on these piles, 

especially if the piles are to remain there for over a year.

Restrict Livestock Grazing from Areas Infested by Weeds – Cattle can bring weed seeds from 

off site where they have been grazing. Until native vegetation has become established, it is 

important to keep livestock out of the area.

5.8.2.3 Treating Weed Sources

If weeds are present on a project site prior to construction, or become established during or 

after construction, then treatments for control or eradication of these plants from the site must 

be assessed. The types of treatments fall into 4 categories (adapted from Massu 2005).
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Figure 5.65 – Burrowing mounds 

(A) are a good indication of the 

presence of northern pocket 

gophers. One gopher can make 

up to 3 mounds per day. Besides 

covering surface vegetation with 

up to 18% of the surface area in 

mounds (Laycock and Richardson 

1975), gophers also eat grass and 

forb roots, weakening or killing 

plants. Tree seedlings are killed 

when the stem and roots are eaten, 

as shown in (B). 115

Manual – Hand-pulling weeds can be the easiest and quickest method of weed control. There 

are several methods or strategies for weeding. One strategy, the Bradley Method, prioritizes 

the areas to be weeded, starting in the areas with the least infestation (best stands of native 

plants) and proceeding to the worst. Once the weeded area is revegetated in native plants, 

weeding is continued into the more infested areas.

Mechanical – Mowing and cutting are mechanical treatments that can reduce the spread of 

seeds if they are done prior to the development of seed heads. Steaming and foaming are other 

mechanical treatments that can kill seeds and young plants.

Biological – Biological control agents exist for some weeds (Massu 2005). Information on 

biological controls can be found at http://www.aphis.usda.gov/ppq/weeds.

Chemical – Herbicides should only be used with the objective of establishing desired species. 

There are many eff ective herbicides on the market but not all are registered for commonly 

occurring weed species. When selecting an herbicide, it is important to fi nd those products 

that are eff ective in controlling the target species yet have a minimal eff ect on non-target 

species. Using an appropriate application rate is an important factor for obtaining the optimum 

eff ectiveness of the herbicide. In addition, timing the application when desirable species are 

dormant could eff ectively protect the species. Treating areas with herbicides, prior to native 

seeding, requires care and a working understanding of the herbicides being used. To avoid 

toxic eff ects on establishing native vegetation after herbicide treatment, it is important to 

know the eff ectiveness, longevity, selectiveness, and application rates of the herbicides being 

considered for the project. Herbicides should only be used to temporarily open a site; the longterm goal is to establish vegetation to take the place of the weeds.

5.9 PESTS

Many plant and animal species pass through or inhabit a newly revegetated site. When these 

organisms become problematic, they are called “pests.” Part of good revegetation planning is 

to recognize the conditions where species might become pests on the project. This chapter 

focuses on mammals, insects, and diseases, that are the most common types of pests found on 

revegetation projects.

Many problems can be prevented through good design and management. For example, 

matching the appropriate plant species and stocktypes to the site reduces the potential of 

damage by insects and diseases. Where deer populations are high, planting unpalatable 

species reduces the risk that deer will over-browse newly planted vegetation or be encouraged 

to browse near the highway, creating a hazard to motorists. In many cases, the best investment 

is to preclude problems by protecting plants instead of attempting to control or destroy pests 

after they move in. However, not every sign of an animal or disease is cause for concern. Some 

loss due to herbivory or disease should be expected. Planning for some replanting after the 

fi rst season is a good strategy to help establish native plants while allowing for some herbivory. 

During early establishment, when plants are most susceptible to life-threatening damage, 

treatment might be necessary. When this is the case, consider the system as a whole and select 

the least impactful, long-term treatment. For example, protection of plants with a physical 
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barrier or a repellent spray might be better in the long-term than introducing a poison into the 

food chain that might also aff ect the animals that prey on the pests.

The following is a general discussion of mammals, insects, and diseases that can cause the most 

problems to reestablishing native vegetation. This is by no means a complete listing of issues or 

of mitigating measures. The reader is directed to other sources, such as Cleary and others (1988) 

and Helgerson and others (1992), for more a more thorough discussion of this topic.

Foraging mammals, such as deer, elk, gophers, and voles, may remove or destroy portions 

of the plant foliage or root systems. Feeding insects will weaken and, in some cases, kill 

establishing plants by feeding on roots, stems, and foliage. Diseases can be transported to 

the site on nursery stock and manifested under stressful transplanting conditions. Problems 

are usually encountered where the species were not appropriate for the site (e.g., dry species 

planted in a wetland), where there was not enough diversity in the species being planted, or 

on sites where soils were limiting (e.g., poorly drained soils). Unfortunately, the eff ects of pests 

on revegetation are not always easy to assess prior to implementation. Often the pest is not 

discovered until after revegetation has taken place.

5.9.1 Mammals

Mammals forage on the foliage, bark, and roots of young seedlings. In moderation, mammals 

will do minimal amount of damage to a revegetation project. Where herbivory is high, however, 

these animals can cause major damage to a newly planted site. The mammals of greatest 

concern to revegetation are the northern pocket gopher, deer, elk, and livestock.

5.9.1.1 Northern Pocket Gophers

Pocket gophers forage on all parts of the plants depending on the season of the year. Seedling 

stems are often completely debarked, thereby killing the tree (Figure 5.65). Gopher damaged 

seedlings lean to one side and are easily pulled from the soil (Helgerson and others 1992). 

Equally disruptive to plant establishment is the amount of soil that is brought to the surface 

during burrowing. Fresh gopher mounds can account for up to 18% of the soil surface (Laycock 

and Richardson 1975) and often bury newly establishing grasses, forbs, and seedlings. Gophers 

prefer soils that are low in rock fragments (<25%) and favor grasses and forbs over shrubs and 

trees. Succulent, perennial forbs, such as lupine (Lupinus spp.), buckwheat (Eriogonum spp.), 

and yarrow (Achillea spp.), are preferred over grasses (Bonar 1995). When present on a site, this 

small mammal can be an immense problem to establishing most plant species, especially those 

being planted from seedlings.

The potential of a revegetation project to become populated by gophers is a function of: 

1) the presence of gophers in the adjoining lands, and 2) the favorability of the project site 

as gopher habitat. It should be assumed that if the project site borders areas populated by 

gophers, they will naturally move into the openings created by the road construction project. 

If the construction project is a poor habitat for gophers (e.g., rocky, steep, high slash), gophers 

will likely be less of a problem.

Prevention and Treatment – Leaving snags near gopher infested sites can help reduce 

populations by providing perches for raptors to prey on gophers. Physical barriers such as 

plastic netting have mixed results in reducing gopher damage. Another strategy is to create an 

unfavorable environment for gophers, including soils high in rock fragments, steep slopes, and 

sites with heavy slash (Bonar 1995). Planting seedlings at higher density or replanting seedlings 

that have been killed by gophers is another strategy. Since grasses and forbs are a preferred 

food source for gophers, planting shrubs and trees and covering the site with a deep mulch 

may discourage high populations.

Control of pocket gophers can be accomplished at various levels of eff ectiveness by trapping 

or baiting, encouraging predators, and protecting with netting or barriers. Trapping and toxic 

baiting appear to be the most widely used method of gopher control (Bonar 1995).

5.9.1.2 Deer And Elk

The new vegetative growth from tree and shrub seedlings is a preferred food source for deer 

and elk. Damage is observed as clean, sharp cuts to the branch or leader stems. Deer and elk 

typically leave scat and tracks on the sites where they browse. The scat is observed as scatterings 
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or piles of large oval pellets. Trees that are annually browsed by deer or elk will remain stunted 

or low-growing for many years (Figure 5.66).

Prevention and Treatment – During the planning stages, consultation with the local wildlife 

and reforestation experts will help assess the potential for herbivory by deer and elk herds. 

Visits to areas adjacent to the project site can also give an indication as to the amount of 

damage that can be expected.

Planting non-palatable species in areas where high deer or elk populations are expected 

is a good preventive measure. Protecting seedlings from deer and elk browsing can be 

accomplished through fencing, application of animal repellents, installing plastic netting 

around the seedling, and planting large seedlings. Animal repellents are applied on or around 

the seedling with the objective of rendering the seedling unpalatable for browsing.

Fencing large planting areas to keep out elk and deer is used in places where herds are 

large. However, placing physical barriers, such as netting or tree shelters, around individual 

seedlings is the most common method of protecting seedlings. Rigid and non-rigid netting 

are commercially available products and are made from photo-degradable plastics that 

should break down after several years in the fi eld (Figure 5.67). They are placed around the 

seedling after it is planted. Tree shelters will also protect seedlings during the early stages of 

establishment. Section 10.4 discusses these treatments in more depth.

5.9.1.3 Livestock

Damage to revegetation projects can be high in areas that are intensively grazed by cows 

or sheep. At high livestock populations, planted seedlings can be injured by rubbing and 

Figure 5.66 – The annual browsing of this 

Douglas-fi r seedling by deer has created 

a seedling that is bushy and stunted with 

many buds. Frost damaged seedlings have 

a similar appearance.

Figure 5.67 – Rigid plastic netting 

is placed around seedlings after 

planting to protect the young 

seedling from animal browsing. 

The plastic is photo-degradable and 

breaks down in several years after 

the seedling is established.
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trampling. Seedlings are typically not browsed. Newly establishing native grass and forb cover 

can be harmed by the high-pressure hoof marks tearing up the new roots and surface soil, 

leaving the site exposed to non-native annual species.

Prevention and Treatment – Restricting the entry of livestock for several years after planting or 

sowing, or until native grasses and forbs have established, is the best prevention measure. This 

is typically accomplished by fencing the entire area being revegetated. Fencing is most eff ective 

when it is installed prior to establishing native vegetation. For this reason, having the fence 

installed as part of the road contract will assure that livestock is controlled prior to revegetation 

work. Working with the local USDA Forest Service or USDI Bureau of Land Management range 

conservationist will be necessary to assure that damage by livestock is kept to a minimum.

5.9.2 Insects

There are a variety of insects that can damage newly planted seedlings. These will be discussed 

briefl y in this section. Since this is a specialized fi eld, the reader is advised to consult technical 

or academic expertise if insect problems are found to be extensive on a revegetation project. 

Insect damage is grouped into four classes (Helgerson and others 1992), based on where insect 

feeding occurs:

 · Sap-suckers – foliage,

 · Root beetles – root system,

 · Terminal feeders – terminal shoots, and

 · Secondary bark beetles – stems.

It is very difficult during the planning stages to determine if insects will be a limiting factor. 

However, the local agency reforestation personnel should be consulted to determine which 

insects pose potential damage.

5.9.2.1 Insects – How to Assess

Damage to seedlings by insects is often overlooked because the injury usually occurs long 

before the seedling shows visible signs of stress. By this time, the insect has often left the 

scene, leaving only the telltale sign of activity. When dead or dying seedlings are discovered, 

it is important to systematically evaluate the seedling from the root system to the terminal 

bud for the presence of insects, insect damage, and disease (which will be discussed in the 

following section). If insects are found, individuals should be collected for later identifi cation. 

It is important to look under the leaves for aphids and scrape the entire seedling with a sharp 

knife to observe boring and tunneling. Much of the damage caused by insects and disease 

occurs under the bark of the stems and roots themselves. A hand lens is helpful to detect 

microscopic damage. The following discusses some of the most prominent insects that 

damage conifer seedlings. Non-conifer species will have their own unique associated pests. 

Nevertheless, determining to which of the 4 classes the insect belongs is a start in making an 

appropriate assessment.

Sap-Suckers – Sap-suckers include the Cooley spruce gall adelgid (Adelges cooleyi) and the 

giant conifer aphids (Cinara spp.) which feed on succulent foliage of tree seedlings. While 

these can cause shoot deformity and foliage loss, aphids will normally not kill seedlings. The 

appearance of aphid ants (which cultivate aphid populations) on the leaves are indications that 

aphids are present.

Root Beetles – The root bark beetles (Hylastes nigrinus) and root-collar weevil (Steremnius 

carinatus) girdle the roots and stems of conifer seedlings and will weaken or kill newly planted 

seedlings. The damage can be mistaken for herbivory by small mammals, but the lack of teeth 

marks and the below-ground location of the damage are indications that the damage is caused 

by root beetles.

Terminal Feeders – The larvae of this group of insects feed on the terminal shoots of young 

conifers, killing much of the new growth. Continued annual attack by these insects can severely 

stunt conifer seedlings. The major insects include white pine weevil (Pissodes strobi [Peck]), 

ponderosa pine tip moth (Rhyacionia zozana), western pine shoot borer (Eucosma sonomana), 

and the cone worm (Dioryctria spp.).
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Secondary Bark Beetles – The Douglas-fi r engraver beetle (Scolytus unispinosus) attacks the 

stems of stressed seedlings, creating galleries under the bark that weaken or kill Douglasfi r seedlings.

5.9.2.2 Mitigating For Insects

Plant a Variety of Species – Insects are often host-specifi c, meaning they attack only one 

species. For this reason a preventative measure is to plant a variety of species. If an insect 

infestation occurs, it would not aff ect all the seedlings planted.

Plant Healthy Stock – Insects often attack weakened seedlings or seedlings under stress. 

Planting only healthy seedlings, appropriate to the site, reduces the potential damage by insects.

Create a Healthy Soil Environment – Seedlings grown on poor sites, or on sites outside of the 

species environmental ranges, will be placed under stress and become candidates for insect 

damage. Planting seedlings on optimal growing sites will produce healthy seedlings resistant 

to insect damage. Judicious use of fertilizers (that is, avoid overfertilization) is also important 

for pest prevention. For example, sucking insects often attack plants that have been overfertilized with nitrogen.

Install Bud Caps – Some terminal feeders can be controlled through the use of bud caps which 

are placed over the terminal in the spring prior to shoot growth (Goheen 2005). Bud caps are 

materials made out of paper or fi ne cloth that temporarily cover the terminal and prevent adult 

insects from laying eggs on the bud.

5.9.3 Diseases

Diseases aff ect all species used in revegetation, but assessing and mitigating for individual 

species is normally not done on revegetation projects. If disease occurs, it is often the result 

of trying to establish plant species in the wrong environment. For instance, species adapted 

to dry environments will be susceptible to root diseases if planted in wet soils where root 

pathogens are present. Species that have evolved to wet soil conditions are less likely to be 

aff ected. While diseases might be present on a site, this does not necessarily mean that plants 

will be aff ected. Much like humans, plants are always surrounded by a variety of pathogens, 

but it is not until they are put under stress that they become more susceptible to infection. The 

resistance of a plant to disease is therefore dependent on its health.

Planting appropriate species, using genetically appropriate stock, purchasing high quality 

plant materials, improving the soil, and mitigating for climate extremes all play an essential 

role in creating healthy plants capable of resisting diseases. If diseases are found on seedlings 

after planting, often they came from the nursery. While diseases will weaken the seedlings 

from the nursery, it is unlikely that the diseases will spread through the soils or site and infect 

other plants. Since the revegetation environment is dissimilar to the nursery or agricultural 

environment, diseases from the nursery tend not to persist on the plant materials once they are 

installed. Plants that have a minor infection might recover when grown in the wild. Diseases 

that run rampant in grass seed beds at seed production facilities are less likely to infect grasses 

when they are seeded on revegetation projects because the growing environment in the wild 

is very diff erent.

5.10 HUMAN INTERFACE

An often overlooked factor of revegetating roadsides is the unplanned eff ects humans can 

have on site recovery. The human interface is the disturbance resulting from human activities 

that limit plant establishment and growth. These potential disturbances must be considered 

very early in the planning stages to assure that they are integrated into the revegetation plan. 

Disturbances fall into two categories – road maintenance and recreation use. Roads must be 

maintained, but sometimes road maintenance activities negatively aff ect the establishment 

and growth of vegetation. Road corridors can also be sites of unplanned recreational use by 

off -road vehicles, which can leave a site compacted and devoid of vegetation.

5.10.1 Road Maintenance

Roads are periodically maintained for many reasons which include: 1) clearance for sight and 

safety, 2) weed control, 3) fi re hazard reduction, 4) winter safety, 5) erosion control, and 6) utilities 

maintenance. Each of these activities aff ect plant growth in either a positive or negative way.
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5.10.1.1 Road Maintenance – How to Assess Impacts on Revegetation

Road maintenance objectives should be understood at the beginning of the project. A 

meeting should be held with the agency that will be overseeing the maintenance of the road 

after construction to discuss how to integrate revegetation and road maintenance objectives. 

Questions or issues to resolve include:

 · Will the ditches be cleaned out or bladed? If so, how far up the cut slope will this activity 

cause instability?

 · Will herbicides be used (Figure 5.68)? If so, how far from the road shoulder? How often?

 · How far away will trees be cut for “line of sight” and will this distance change on curves?

 · What utilities are in the road corridor and will vegetation aff ect them?

 · Are the roads treated with gravel during the winter for traction? If so, how much gravel 

is annually applied? How far is it swept into the road shoulder or road corridor? Are the 

gravels recovered by scraping the shoulders?

 · Is fi re an issue and will fi re protection treatments include thinning of vegetation?

 · What about salts or other non-herbicide contaminants?

This is a partial list, and every project will have its own set of questions. The more these issues 

can be addressed early in the planning stage, the more eff ective will be the revegetation plan.

5.10.1.2 Mitigating For Road Maintenance Impacts

Blading for Erosion Control – Ditchlines at the base of steep cut slopes are depositional areas 

for rock and soil that have moved down from the slopes above. The rock and soil may fi ll the 

ditches, disrupting the fl ow of water in the ditch and creating potential road drainage problems 

during storms. Blading is the removal of the material that has fi lled in the ditchline and is a 

normal maintenance procedure for erosive cut slopes. This operation not only removes plants 

that were established in the ditchline, but also destabilizes the surface slopes immediately 

above the ditch. This can aff ect the revegetation of the entire slope. Mitigating measures 

include engineering design that reduces slope gradients (See Section 5.6.6.2, Mitigating for 

Steep Slope Gradients) or changing the road drainage system so that cleaning of ditches is not 

necessary. If neither measure is possible, assess whether it is worth implementing revegetation 

treatments, since revegetating unstable slopes is usually not successful.

Herbicide for Vegetation Control – Contact the government agency responsible for controlling 

weeds or vegetation in the road corridor and discuss their strategy for weed control. In areas 

where vegetation must be maintained, signs can be issued to notify operators not to apply 

herbicides (Figure 5.69). Do not apply revegetation treatments to areas where herbicides will 

be used to control roadside vegetation.

Graveling for Winter Safety – In areas where gravels are applied to road surfaces for traction 

during snow or icy conditions, there will be a buildup of gravels on the sides of the road through 

Figure 5.68 – Road maintenance 

treatments for control of vegetation 

include the use of herbicides on roadsides. 

There is no need to seed these areas if 

they will be treated chemically. A meeting 

with road maintenance personnel to 

understand how roadside vegetation will 

be managed can save revegetation costs 

and eff orts.
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sweeping of the road surface or snow-blowing. Vegetation that has been established in these 

areas is often completely covered with gravel when the snow melts. It is important to learn if 

the road maintenance agency will recover this gravel for reuse, or let it accumulate. If gravel is 

recovered, this area will be in constant state of disturbance. Determine the salvage distance 

and do not apply seeds in this zone. In areas where gravels are not salvaged, select the species 

that will survive and grow in this unique growing environment. One strategy is to select species 

that respond favorably to being covered by gravels. These include species such as manzanita 

and willows that root from their stems when covered by soil or gravel. Tap-rooted species, such 

as lupines, can take advantage of such conditions because they can access moisture deep in 

the gravel deposits (Figure 5.70). Examine shoulders of existing roads to identify species that 

have adapted to these conditions and use these species for revegetating these areas.

Clearance for “Line of Sight” and Safety – Trees and shrubs are often thinned or removed 

in areas where line-of-sight is impeded. Good communication with the government agency 

responsible for maintaining the road during the planning phase will help identify those 

areas not suitable for shrub and tree species. Select grasses and forbs or low growing shrubs 

(<2 to 3 ft tall) for these areas.

Protection of Utilities – Do not plant trees under or near utility structures, such as power lines. 

Discuss the planting plans with the maintenance agency to fi nd out if there are other utilities 

that need protection.

5.10.2 Recreational Use

The road corridor is often used for recreational purposes that can disturb established 

vegetation. This recreation is not usually sanctioned or intended, but it exists in certain areas 

nonetheless. Recreational disturbances include off -road vehicle travel, mountain bike use, trails 

to recreational sites, and Christmas tree cutting.

Figure 5.69 – Placing no-spray signs is a 

method of identifying areas to protect from 

herbicide application.

Figure 5.70 – Gravel applied to road 

surfaces in the winter for traction is 

swept or blown to the side, burying 

vegetation. Some species, such as 

Lupinus spp. (inset in lower left of 

photograph), have adapted to these 

conditions and do well. Species such as 

pinemat manzanita (Arctostaphylos 

nevadensis) also do well when covered 

by gravels because the plant will 

produce roots from buried stems.
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5.10.2.1 Recreational Use – How to Assess Impacts on Revegetation

The environmental assessment should identify the public’s demand for these activities and 

how they will aff ect short and long term vegetation goals. Obliterated roads, for instance, are 

often desirable places for off -road vehicles because they are open and fl at. Roads bordering 

recreation destinations, such as favorite fi shing holes, will have demands for access trails or 

scenic views that the public does not want blocked by tall vegetation. Public scoping should 

identify these needs.

5.10.2.2 Mitigating For Recreation Impacts

There are several approaches to mitigation, most of which are forms of awareness, protection, 

and exclusion. Intruders can be excluded physically with barriers, such as ditches, fences, and 

large rocks. Before these measures are put into place, communication should be tried fi rst. 

For example, a sign explaining native revegetation eff orts may help make potential users aware 

that they should take their activities elsewhere. Local residents are often great sources for ideas 

on how to approach these problems; off -road vehicle clubs are another. Educating the public 

on the purpose for the revegetation treatments can go a long way towards protection. Short 

paragraphs in the local newspapers or on the FHWA website for each project will help. Using 

local contractors to implement the revegetation work brings ownership to the project and the 

people can be great sources for support in the community.

5.11 INVENTORY SITE RESOURCES

Most project sites contain resources that can be used to meet revegetation objectives. 

Identifying site resources early in the planning process is essential so that potential resources are 

not inadvertently wasted. The more you can work with the resources and assets of the site, the 

more cost-eff ective, effi cient, and eff ective the revegetation eff orts will be. Physical resources 

to inventory include topsoil, duff , and litter, parent materials, woody materials, plant materials 

C1

1+300 1+350 1+400 1+450 1+500

Undisturbed

30

N

12"

loam

30

Sandy loam

40

> 60"

100

Litter, duff

Granite

0-14"

Massive 

with some 

fracturing

Massive 

with some 

fracturing

1"

Undisturbed

45

N

14"

loam

25

Sandy loam

35

> 60"

100

Litter, duff

Granite

0-14"

1"

Highly 

fractured

Undisturbed

35

NE

14"

loam

20

Sandy loam

45

> 60"

100

Litter, duff

Granite

0-14"

2"

Highly

fractured

Undisturbed

45

S

6"

loam

40

Clay loam

45

> 40"

100

Litter, duff

Basalt

0-14"

0.25"

Highly

fractured

Undisturbed

40

S

6"

loam

45

Clay loam

35

> 40"

100

Litter, duff

Basalt

0-14"

0.25"

C2 C3 C4 C5 Plot Number

Location

Site Condition

% Slope

Aspect

Topsoil Depth

Topsoil Texture

Topsoil % Rock

Subsoil Texture

Subsoil % Rock

Total Soil Depth

% Soil Cover

Soil Surface Cover

Depth of Cover

Parent Material

Fracturing

Sample Depth

Project: Summerville Highway – Topsoil Salvage

Figure 5.71 – Example of a form for collecting topsoil information.
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(seeds, seedlings, and cuttings), large rocks, and water (seeps, springs, creeks). Intangibles 

should also be considered, such as community cooperation and the local knowledge base.

5.11.1 Survey Topsoil

One of the most important site resources for revegetation is topsoil. If considered early 

in the planning process, topsoil can be salvaged and reapplied to disturbed sites after 

construction. This is one of the best ways of increasing productivity on a disturbed site (See 

Section 10.1.4, Topsoil).

Topsoil is inventoried early in the planning process to evaluate topsoil quality and depth; 

costs, removal, and storage feasibility; and any other associated costs. Topsoil recovery is an 

expensive operation requiring knowledge of soil attributes. For this reason, a thorough soil 

survey must be conducted on those locations that will be disturbed. An example of soil and 

site information commonly collected for topsoil recovery is shown in Figure 5.71. The road in 

this example is planned through undisturbed forested lands. Soils data is collected every 50 

meters (at road stations) due to the variability of the soils in this area. Where soils are very 

uniform, distances between plots can be increased. Soil texture, rock fragments, and depth of 

the topsoil are measured in the fi eld. At selected intervals, or on diff erent soil types, a sample 

is collected for lab analysis.

During topsoil survey, other site attributes that could aff ect the quality of topsoil should be 

noted. The most obvious are the locations of all noxious weeds. These sites should be avoided 

during topsoil salvage operations since the reapplication of these soils would spread these 

species across the project area.

The outcome of the topsoil survey is a short report and map in the revegetation plan showing 

the areas to salvage topsoil and the depth of salvage. If there are great diff erences between 

topsoil depths to salvage, this should be shown on the map. The report should discuss the 

fertility of the topsoil, how it should be stored, and whether the duff and litter is removed 

and stored separately. Areas should also be identifi ed where topsoil should not be collected. 

The most typical areas are those which support undesirable non-native vegetation.

5.11.2 Survey Duff And Litter

Duff and litter are the dead plant material that has accumulated on the surface of the soil. 

The level of decomposition diff erentiates litter from duff . Litter is the layer of recently fallen, 

undecomposed leaves, needles, and branches; duff (which occurs immediately below the 

litter layer) is litter that is decomposed beyond recognition. The duff layer is dark, light-weight 

organic layer that occurs under forest environment. It is a large reserve of nutrients and carbon, 

and has a high water-hold capacity. Litter and duff layers protect the soil from erosion by 

absorbing the energy of rainfall impact and reducing overland fl ow. The litter and duff layers 

combined can be very thick, ranging from 1 to 4 inches depending on the productivity and 

climate of the site.

Figure 5.72 – Slash material 

can be chipped on site to 

reduce fi re hazards and 

increase line of sight. In this 

photograph, brush and 

trees on cut slopes are cut, 

chipped, and blown back on 

the slopes as mulch.
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Litter layers typically have viable seeds that have fallen from the overstory vegetation. Under 

the right conditions, these seeds will germinate. If collected, stored and reapplied correctly, 

this natural seed bank can be used as a seed source. See Section 10.1.3.11, Litter and Duff for 

discussion of methods for collection and application.

Litter and duff layers can be assessed at the same time that topsoil surveys are conducted. 

The measurement is simple; using a ruler at collection intervals, record the thickness of the 

litter and duff layers.

5.11.3 Subsoil And Parent Material

Certain subsoils and parent materials can be salvaged during road construction and used to 

produce manufactured topsoil (See Section 10.1.4.5, Manufactured Topsoil). Textures low in 

rock content, including sandy loams, silt loams, loam, and sandy clay loams, are often good 

materials for manufactured soils. These are often found in areas where the parent materials are 

derived from alluvial or windblown deposits. They include river sands, pumice, volcanic sands, 

and loess.

5.11.4 Woody Material

Woody material consists of live and dead plant materials that will be wasted in the construction 

of the road project. This material includes tree boles, root wads, bark, and branches. During 

clearing and grubbing, these materials are often concentrated in piles and burned. All of these 

materials can be chipped or mulched and used as surface mulches (See Section 10.1.3.7, Wood 

Fiber) or soil amendments (See Section 10.1.5, Organic Matter Amendments). Large wood can 

be used for biotechnical engineering structures, obstacles for erosion control or as downwoody material for site productivity. Using these materials for revegetation purposes will lower 

overall project costs.

5.11.5 Plant Materials

As discussed under Section 10.2, plant materials consist of seeds (See Section 10.2.1, Collecting 

Wild Seeds), plants (See Section 10.2.3, Collecting Wild Plants), and cuttings (See Section 10.2.2, 

Collecting Wild Cuttings). If collected and stored correctly, these materials can be used to 

revegetate disturbed sites. Surveys of the project site prior to construction will indicate location 

and abundance of plant materials.

5.12 PHASE TWO SUMMARY AND NEXT STEPS

Planning Phase Two identifi es site factors that limit revegetation, defi nes mitigating measures, 

and inventories site resources. The next phase is Phase Three, where vegetation will be assessed 

and analyzed in order to match plant materials and revegetation methods to the site attributes. 

In Phase Four, a comprehensive strategy is developed that integrates the components from 

each phase into the Revegetation Plan.
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6 PLANNING PHASE THREE: VEGETATION ANALYSIS 

6.1 INTRODUCTION

We are now in Phase Three of the process of planning. Phase One began with defi ning the 

overall objectives of the revegetation project, the management areas (revegetation units), and 

the natural models (reference sites). Phase One included conducting preliminary assessments of 

vegetation, climate, and soils, as well as defi ning appropriate Desired Future Conditions (DFCs) 

for each revegetation unit. In Phase Two, site factors that might limit or aid the establishment 

of vegetation were identifi ed and analyzed, including which limiting factors in the roadside 

environment could be mitigated. Now that the environment has been defi ned, the task is to 

fully analyze the vegetation of the site.

In Phase Three, you will gather information about native vegetation on the reference sites and 

revegetation units. With this information, you will be able to refi ne the DFCs and consider the 

most appropriate revegetation methods to meet your objectives. By the end of Phase Three, 

you should have:

 · Completed the vegetation assessment of all reference sites, creating a comprehensive 

species list and defining plant communities and successional processes;

 · Determined which species and groups of species will be used on the project; and

· Identified target plant requirements and created a menu of potential stocktypes and 

plant establishment methods for revegetating the site.

In Phase Four, elements from these previous phases will be pulled together into a comprehensive 

revegetation strategy.

6.2 VEGETATION ASSESSMENTS

The objective of assessing vegetation is to: 1) create a comprehensive species list, 2) defi ne plant 

communities, and 3) identify successional processes. To do this, information about species and 

communities that was gathered in Phase One is revisited and supplemented as necessary with 

additional fi eldwork. This information will be used to select species, stocktypes, and planting 

strategies for revegetation.

To develop a comprehensive species list and defi ne plant communities and processes, you 

will need to revisit your maps and literature, and review the fi eld data that you collected from 

reference sites in Phase One. These include:

 · Vegetation and soils maps including noxious weed maps;

 · Plant association guides;

 · Maps and literature about threatened, endangered, or sensitive species;

 · Information about roadside management practices;

 · Species lists and vegetation descriptions from literature and/or local contacts; and

 · Species lists and vegetation descriptions from reference sites and project area.

6.2.1 Organize the Comprehensive Species List

Compile a comprehensive species list and organize your list into life forms:

 · Trees, 

 · Shrubs,

 · Annual grasses,

 · Perennial grasses,

 · Annual forbs,

 · Perennial forbs, and

 · Sedges and rushes.
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6.2.2 Defi ne Plant Communities and Ecological Settings

Species should also be identifi ed according to plant communities and ecological settings, 

as described in Phase One. For example, communities should be grouped as they appear in 

diff erent ecological settings:

 · Hot/dry, 

 · Warm/dry, 

 · Cool/moist, and

 · Cold/dry. 

6.2.3 Identify Successional Processes

Species should be identifi ed according to their successional group:

 · Early seral, 

 · Mid seral,

 · Late seral, and

 · Climax.

The next step is to analyze the above information so that you can select species, nursery 

stocktypes, and outplanting methods to match the needs of your project. 

6.3 DEVELOP SPECIES LISTS FOR THE PROJECT

From the vegetation assessment, each species on the comprehensive species list is considered 

for potential use on the project. This is accomplished by screening potential species through 

the following criteria:

1) Workhorse species,

2) Working groups (groups of workhorse species),

3) Specialist species, and

4) Research and trial species.

6.3.1 Determine the Workhorse Species

“Workhorse species” is a term used to describe locally-adapted native plants that have the 

following characteristics:

 · Broad ecological amplitude (that is, occurring in many diff erent environments),

 · Abundance, and

 · Ease of propagation and ability to survive well on roadsides.

If native species fulfill all three requirements, they will be the main species used in revegetation. 

Tables 6.1 and 6.2 illustrate how the process of selection works.

6.3.1.1 Amplitude

Workhorse species have broad ecological amplitude, occurring in many diff erent environments. 

The main criterion for workhorse species is amplitude (Table 6.1), or the recurrence of the 

species across a wide array of ecological settings. For example, if surveys revealed the same 

species on both hotter, drier environments and north-facing slopes on the project, that species 

has a high ecological amplitude.

6.3.1.2 Abundance

Abundance indicates the quantity, dominance or cover of species on each revegetation unit 

(0=never, 1=rare, 2=common, 3=abundant) (Table 6.1). It is summarized for the road project by 

adding together the abundance ratings given for the species in each revegetation unit.
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Table 6.1 – Analyzing amplitude and abundance. From species data collected at all reference 

sites, develop a comprehensive species list for analysis.

Abundance indicates the quantity, dominance, or cover of species on each revegetation 

unit (0=never; 1=rare; 2=common; 3=abundant). It is summarized for the road project by 

adding together the abundance ratings given each revegetation unit. In the case of Achillea 

millefolium, the abundance is 13 (out of a total of 15), indicating that it is a dominant species in 

all revegetation units. Allium fi brillum has a relatively low abundance of 2, which indicates that 

it is not abundant on this project.

Amplitude indicates the relative presence of a species on a project. It is the sum of the presence 

of each species in each revegetation units. For instance, Achillea millefolium was found on 

reference sites of all 5 revegetation units, so the amplitude is 5 indicating that this species is 

widely distributed. Allium acuminatum on the other hand, was found only on one reference site 

of a revegetation unit, and therefore has an amplitude of 1.

Scientific Name

Achillea millefolium

(common yarrow) 2 3233 5 13

3 3 1 2 1 5 10

0 1 3 2 1 4 7

2 000 1 2 3

3 1 323 5 12

3 230 1 5 9

2 1 1 0 1 4 5

2 1 2 1 1 5 7

0 0030 1 3

2 0000 1 2

0 0030 1 3

0 0020 2 5

Abies grandis

(grand fir)

Abies lasiocarpa

(subalpine fir)

Agastache urticifolia

(horsemint)

Agoseris aurantiaca

(orange agoseris)

Agoseris glauca

(pale agoseris)

Agoseris grandiflora

(bigflower agoseris)

Allium acuminatum

(tapertip onion)

Allium fimbriatum

(fringed onion)

Allium macrum

(rock onion)

Allium madidum

(swamp onion)

Warm.

Dry

Cool,

Moist

Cold,

Dry Riparian

1 2345

Meadow Amplitude Abundance

Acroptilon repens

(Russian knapweed)

127

6.3.1.3 Ease of Propagation

Species that have high amplitude and are abundant may also lend themselves to propagation. 

Ease of propagation usually involves the following characteristics:

 · Plant materials (seeds, seedlings, or cuttings) are relatively easy to collect and process;

 · Seeds, plants, and cuttings are easy and inexpensive to propagate and culture in 

a nursery;

 · Seeds store well (longevity);

 · Seeds do not have special requirements for breaking dormancy.

It is now possible to determine which species are potential workhorse species for your project. 

The species that score high in amplitude, abundance, and ease of propagation will be the 
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Table 6.2 – Selecting species to propagate. The comprehensive species list can be used to 

determine the species that are most appropriate to use on the project. Workhorse species 

criteria are based on amplitude, abundance, and ease of propagation. A species such as 

Achillea millefolium, for instance, fi ts all criteria. Whether this species is propagated depends 

on whether it is a member of a particular working group and the objective of the project. Since 

this species fi ts into the “visuals” working group, and visuals are an important objective of this 

road project, this species will be selected for propagation. Agastache urticifolia is also showy 

and has a high amplitude and abundance. However, very little is known about the propagation 

of this species. This species has the potential of being a workhorse species, but will be placed on 

development status until more information or trials can be established to determine how easy it 

is to propagate. 

Allium fi brillum and Allium macrum are specialist species that occur together in a unique 

habitat. Since this road project provides an opportunity to enhance this habitat, these species 

are placed in a “conservation” working group. These species are considered specialists because 

they have low abundance, low amplitude, and little is known about how to propagate them. 

These species will be selected for propagation, however, because of the important role they play 

in restoring a unique habitat. Since little is known about seed propagation, seeds will be sent to 

the nursery for propagation into bulbs. The comprehensive species list also identifi ed Acroptilon 

repens, a noxious weed species, in several of the revegetation units.

Scientific Name

Achillea millefolium

(common yarrow) PF E N – 5 13 Easy Existing

T L N – 5 10

T L N – 4 7

PF E to M I N/A 2 3

PF E N – 5 12 Unknown Potential

PF E N – 5 9

PF E N – 4 5

PF E N – 5 7

PF E N – 1 3

PF E N – 1 2

PF E N – 1 3

PF E N – 2 5

Visual

Visual

Conservation

High

Priority

Conservation

High

Priority

Trials

Abies grandis

(grand fir)

Abies lasiocarpa

(subalpine fir)

Agastache urticifolia

(horsemint)

Agoseris aurantiaca

(orange agoseris)

Agoseris glauca

(pale agoseris)

Agoseris grandiflora

(bigflower agoseris)

Allium acuminatum

(tapertip onion)

Allium fimbriatum

(fringed onion)

Allium macrum

(rock onion)

Allium madidum

(swamp onion)

Life

Form1 Succession2 Origin3 Weeds4 Amplitude Abundance Ease of

Propagation Work Horse Specialist WorkingGroup Development

Acroptilon repens

(Russion knapweed)

1 Life forms: First letter stands for annual (A) or perennial (P). Second letter stands for trees (T), shrubs (S), grasses (G), forbs (F),

 sedges and rushes (W).

2Succession: Early seral (E), mid-seral (M), late seral (L), and climax (C).

3 Origin: Native (N), introduced (I).

4 Weeds: Passive (P), aggressive (A), noxious (N).

128
Figure 6.1 – Example working group. 

A comprehensive species lists for recovered 

reference sites was created during the 

assessment phase. Four species commonly 

occurred together in many of the reference 

sites. Venus penstemon (Penstemon 

venustus), scarlet gilia (Ipomopsis aggregata),

phacelia (Phacelia heterophylla), sedum 

(Sedum stenopetalum), and (not pictured) 

mountain brome (Bromus carinatus)

emerged as a potential “working group” for 

this site. This working group of four forbs and 

one grass was utilized to revegetate the southand west-facing (hot-dry) slopes on this 

project. (Weston-Elgin Road Project, Umatilla 

National Forest, Oregon.)

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workhorse species you will choose to utilize on the project. Table 6.2 gives an example of how 

workhorse species were identifi ed from a comprehensive species list.

6.3.2 Develop Working Groups

The goal of roadside revegetation is not merely to establish plants, but to create functioning, 

sustainable plant communities. For revegetation purposes, a “working group” is a mix of 

workhorse species developed for a specifi c ecological function or management objective. One 

of the best ways to identify working groups is to review the comprehensive species list and 

determine which workhorse species commonly occur together on similar reference sites. For 

example, if fi ve species that commonly occur together on recently disturbed reference sites 

have been identifi ed, you have probably identifi ed a working group.

Working groups should also meet both short- and long-term project goals. When designing 

working groups, remember that it is possible to establish diff erent species at diff erent 

times. For example, grasses may need to be established early for controlling surface erosion. 

Outplantings of shrubs or trees could be done later to increase species diversity and encourage 

long-term slope stability. Workhorse species and working groups are not only mid and late 

seral, but also climax species.

The groups are further defi ned by their ability to fulfi ll certain management criteria. For example, 

can this group of plants be utilized (perhaps with some modifi cation) to perform functions 

that fulfi ll project objectives, such as weed control, conservation goals, soil stabilization, or 

visual enhancement? 

6.3.2.1 Weed Control

One of the most important ecological functions that plants can serve during revegetation is 

to occupy the site so there is no niche available for invasive species to establish. By occupying 

ecological niches from spring to fall with a combination of annual and perennial native species, 

site resources such as moisture, nutrients, and space, are denied to undesirable species. Working 

groups that are eff ective in controlling weeds are usually composed of a mix of forbs, grasses, 

grass-like species, and trees and shrubs that exploit the whole growing season and occupy 

multiple ecological niches (Sheley 2005).

6.3.2.2 Visual Enhancement

A high-visibility site might call for a species mix to include wildfl owers and other showy 

plants for roadside beautifi cation. These species can be practical “workhorses” that provide 

valuable functions, but also maximize color and visual enhancement throughout the season 

(Figure 6.1).
Figure 6.2 – Example of a specialist 

species. Aspen do not meet 

“workhorse” criteria because they 

are challenging to propagate and 

require special protection during 

outplanting. However, for a project 

in Umatilla National Forest, Oregon, 

aspen are important for ecological 

reasons and societal goals; therefore, 

aspen are included in revegetation as 

a “specialist” species.

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6.3.2.3 Erosion Control

On sites where erosion control is an important management objective, the working group 

would be based on plants that are highly eff ective for erosion control. This includes species 

which germinate and grow quickly, produce a high ground cover, generate biomass throughout 

the season, and survive for several years. 

6.3.2.4 Conservation Enhancement

As a functioning plant community, the working group increases the ecological health and 

biodiversity of project sites. In some cases, a working group will specifi cally focus on a group 

of species that are important for ecological and/or societal reasons. These can include sensitive 

species or species that are desired by the public. 

6.3.3 Identify Specialist Species

Working groups will not always be made up of workhorse species and there may be a need 

to propagate “specialist” species. The development of the working groups for a revegetation 

project will determine which additional specialist species will be needed. Since there may be 

very little information about the propagation of specialists, the number of species placed in 

this category should be prioritized and limited. If only a small number of specialist plants are 

needed, then other revegetation methods besides seed propagation should be considered. 

These include wild and nursery grown cuttings and plants. Some areas may contain special 

microclimates or soils that require a unique mix of species, or working group, that are typically 

not available. Seeps, springs, and serpentine soils are examples of some special environments. 

The important concept is that, for each project objective, a working group can be developed 

to meet that objective.

6.4 IDENTIFY TARGET PLANT REQUIREMENTS

Now that you have a list of which species to use for revegetation, the challenge is to determine 

how to propagate them and what is the best plant material for a particular site or objective.

One of the most useful tools for selecting the plant materials best suited to the project is the 

Target Plant Concept (Landis and others 2006). The Target Plant Concept is a holistic way of 

integrating how aspects of plant propagation, project site characteristics, and outplanting 

methods aff ect the selection of appropriate plant materials. The concept is based on the 

premise that there is no such thing as an “ideal” all-purpose seed mix or stocktype that will 

always work in any situation. Instead, the fi tness of the plant material is determined by its 

appropriateness to the site in which it will be outplanted.

The Target Plant Concept consists of 6 requirements for establishing native plants (Figure 6.3). 

At this point in the process, two of them have been covered: the objectives for establishing 

vegetation, and the factors that possibly play the largest role in limiting plant survival and 

growth on each revegetation unit.
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2. Type of Plant Material

5. Timing of Outplanting Window

6. Outplanting Tools and Techniques

3. Genetic Considerations

4. Limiting Factors on 

 Outplanting Site

1. Objectives of Outplanting Project

Figure 6.3 – The Target Plant 

Concept identifi es 6 requirements 

for establishing native plants 

(adapted from Landis and 

Dumroese 2006).

131

The remaining questions to ask are:

 · What are appropriate genetic sources for each species?

 · What type of plant material should be used (seeds, cuttings, or plants)?

 · What methods will be used to install plant materials and what post installation plant 

care is appropriate?

 · What is the proper season for outplanting or seeding (the outplanting or 

seeding window)?

6.4.1 Ensure Local Adaptation and Maintain Genetic Diversity

It is important to know the original collection source of seeds, plants, or cuttings to help ensure 

better long-term adaptation to local conditions and protect the genetic resources of local plant 

communities. Seed transfer guidelines (how far plant material can be transferred from point of 

origin to the project) have been developed for many forest tree species. This was the outcome of 

years of research that revealed that failures in tree planting establishment were sometimes the 

result of moving seeds too far from their source of origin. Although work is underway, guidelines 

for plant material movement are lacking for many native grasses, forbs, and shrubs used in 

revegetation activities. As a result, many native plants of inappropriate or unknown origin are 

being sold and planted in revegetation projects, despite the strong concerns. Mechanisms are 

available to help revegetation specialists choose appropriate materials (Insets 6.1 and 6.2).

6.4.2 Consider Plant Establishment Methods

Once species have been chosen and genetically appropriate sources of plant materials have 

been identifi ed, the next step is to determine the most appropriate plant materials for the 

project. Revegetating with native plants commonly involves multiple methods to reestablish 

vegetation on the project site. Possibilities to consider are:

 · Maximizing natural regeneration/recovery,

 · Direct seeding, and

 · Outplanting nursery stock.

In areas with relatively good soil stability that are bordered by healthy populations of viable 

native species, the existing seed bank and natural regeneration processes is a key part of 

re-establishing native vegetation on road sites. Minimizing the road footprint and damage 

from road construction is an important aspect of any type of planning, but will be especially 

key if revegetation tactics will involve supporting natural regeneration over more intensive 

revegetation interventions. In these cases, as long as topsoil is saved, the disturbance from 

road construction might serve to scarify the native seed bank. Often the option of maximizing 

natural regeneration is not suffi cient to fully revegetate a roadside environment; nevertheless, 

it should always be considered as a possibility. Salvaging and reapplying duff and litter layers 

to disturbed surfaces can aid in maximizing natural regeneration. The revegetation plan should 
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Inset 6.1 – Locally Adapted Plant Materials

(Excerpted and adapted from Withrow-Robinson and Johnson 2006)

For revegetation success, much more is involved than just creating a list of native species. 

Seed origin and genetic foundation (number of parent plants) must also be considered. 

Origin of seed collections and genetic foundation are often overlooked in revegetation 

projects. However, these are key factors to help ensure survival of the plants and protect 

local genetic resources.

Distinguishing Native and Local

The defi nition of what is “native” and what is “local” is not always agreed upon. For many 

people, a native species is one that was in the area before European settlement. However, 

many of these “natives,” including trees and shrubs common in riparian communities, 

are widely distributed across many states and huge geographical regions. In Oregon, for 

example, native trees such as Douglas-fi r (Pseudotsuga menziesii), ponderosa pine (Pinus 

ponderosa), western white pine (Pinus monticola), Oregon white oak (Quercus garryana), and 

black cottonwood (Populus trichocarpa) all range from Canada to Mexico, and, in some cases, 

from the Pacifi c to beyond the Rocky Mountains. Many herbaceous plants, such as yarrow 

(Achillea millefolium), also have very broad distribution. Each is native to, and survives in, a 

wide range of conditions across a broad landscape beyond Oregon. This is possible because 

local populations of each species have adapted to local conditions that vary with elevation, 

latitude, rainfall, temperature, and much more. For widely distributed species, “native” does 

not necessarily mean “local.” Plants from the Cascade Mountains in Oregon would not be 

expected to be well adapted to the Oregon Coast Range. The same species may occur in 

both locations, but the climates and soils to which the local populations have adapted are 

very diff erent between these two areas. This principle has been illustrated through decades 

of experience with forest tree species in North America and Europe. Local plant material 

sources have been shown to perform better than non-local sources of native species in 

many reforestation projects. Such experiences in forestry indicate that strict attention to 

source of origin for planting materials in revegetation activities is important.

Transfer Guidelines

In recognizing the need to use native species of local origin, it is important to determine 

how far plant materials can be moved and still be considered local. This question can be 

addressed through the use of transfer guidelines that recommend how far seeds or other 

plant materials can be transferred from their point of origin.

There is no magic number to indicate how far a plant might be successfully moved (e.g., within 

a 50 mile radius). One problem is that “local” is best defi ned in terms of the environment 

(local climate and soils) rather than in absolute distance. Many factors contribute to the 

environmental conditions to which a plant species must adapt, including rainfall, maximum 

and minimum temperatures, aspect, soil drainage and pH. The scope of adaptation also 

varies greatly between species. Some species (generalists) can be moved much farther 

than others (specialists) and still be well adapted to local conditions and regions. Thus, 

transfer guidelines vary from species to species and from region to region. Developing 

useful transfer guidelines is a slow process, incorporating several research approaches and 

computer models. Although guidelines have been developed for only a small number of 

native plants, work is underway on important herbaceous species.

Seed Zones and Elevation Bands

A common type of transfer guideline used to help managers identify appropriate sources 

of plant materials is the seed zone map developed for most of the western states. The seed 

zone map divides each state into geographic areas within which plant materials can be 

transferred with a minimal risk of being poorly adapted. Seed zones help identify where 

plant materials originated and how far they can be moved. Figure 6.4 shows seed zones 

for western redcedar and Douglas-fi r. These zones represent areas of fairly uniform 

environmental conditions. In mountainous regions, elevation bands within each zone are 

used to further defi ne adapted areas.
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Figure 6.4 –

Example of seed 

zones for 

Douglas-fi r and 

western redcedar 

(St. Clair and 

Johnson 2003; 

Withrow-Robinson 

and Johnson 2006).

Douglas-fir western redcedar

133

Seed zone maps are not perfect, since variation of adaptive traits is often continuous across 

the landscape rather than showing distinct boundaries as delineated in a seed zone map. 

Forest tree seeds and seedlings that are available from seed companies and nurseries are 

usually identifi ed by their seed zone, which makes it easier to purchase appropriate materials 

for your project. However, for many other species of interest, it can be diffi cult to fi nd plant 

materials of known origin. 

One variation of the seed zone approach that could be used for other native species is the 

focal point seed zone. Beginning with a known point, such as a project area, this approach 

uses the same environmental factors, genetic information, and GIS technology that are 

used to develop seed zones or to construct customized focal point zones for that project 

area. The focal point approach is conceptually straightforward and logical, but has some 

practical limitations relating to source tracking and maintaining availability of growing 

stock. It is currently used more for herbaceous (non-woody) plants grown directly for seeds 

than for woody plants. This approach also gives the revegetation specialist the opportunity 

to “shop” for reliable plant material sources whose origin is within the customized focal 

point seed zone. Several organizations (e.g., the Native Seed Network) have established 

systems to track the collection and propagation of native species using the focal point seed 

zone approach.

Seed zones are further delineated by elevation bands. Depending on the species, elevation 

bands are delineated in increments of 500 to 1,000 ft. Some species, such as western white 

pine (Pinus monticola) can be moved across all elevations.

Ecoregions

Ecoregions may be substituted for seed zones to guide the transfer of plant materials. 

Ecoregions are defi ned areas of similar geographic, vegetative, hydrologic, and climatic 

characteristics, that are divided into diff erent levels, each level representing increasing 

degrees of detail. Because ecoregion maps identify areas with similar environmental 

characteristics, they may be useful to help determine initial seed zones. Several ecoregion 

maps have been developed. The map developed by the U.S. Environmental Protection 

Agency (EPA) has four levels, from coarse (Level I) to fi ne (Level IV). When other transfer 

guidelines are lacking, EPA Level III ecoregions, in conjunction with elevation bands, may 

be suitable to serve as temporary seed zones. Genetic research in forest trees has led to 

further divisions for most species and seed zones that are smaller than Level III ecoregions, 

so this might be considered a minimum starting point for guiding source selection of other 

revegetation species.

Since research-based transfer guidelines for most native plants do not exist as yet, the issue 

is often simply overlooked. This may lead to mistakes in selecting plant materials. Buying 

whatever plant materials are available from an easy or inexpensive commercial source 

can lead to the introduction and use of inappropriate plant materials. On the other hand, 

restricting acquisition to plant materials from the project site, or its immediate area only, 

can lead to loss of genetic variation and other issues such as delays in obtaining suffi cient 

number of seeds. Neither is a satisfactory solution, and some guidance is needed. Until there 

is genetic data for each native species used in revegetation, seed transfer guidelines using 
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seed zones, focal point seed zones, and ecoregions are a fairly safe and conservative option 

for most native species. What is known from a century of forestry experience is that seed 

source is an important issue that should not be ignored by revegetation specialists.

Genetic Variation

Another important issue in selecting native plant materials is maintaining genetic variation 

in the populations established in revegetation work. Plant populations must be genetically 

variable to be able to adapt to new stresses. Collection and propagation procedures need 

to conserve suffi cient genetic diversity to buff er environmental changes in both the short 

term (years) and long term (decades or centuries). Also, a suffi cient number of unrelated 

seed parents (in outcrossing species) must be included to ensure that inbreeding will not 

become a problem in the future. Both issues come down to numbers; the more plants that 

contribute to the new population, the more genetic variation will be captured and the lower 

the likelihood that relatives will mate (less inbreeding). These criteria should be considered 

by managers, whether they are buying plant materials or collecting their own. 

Failing to consider genetic variation when selecting plant materials can potentially have 

signifi cant consequences on the viability and sustainability of revegetation eff orts. Yet it is 

easy to imagine how variability can be eroded. If plants are propagated from a very small 

and inadequate sampling of the population, genetic variation of the propagated plants will 

be greatly reduced.

Reproductive strategies vary widely between species. No single collection and propagation 

protocol will ensure the genetic integrity of all types of plants used in revegetation. However, 

the issue of genetic variation cannot be ignored. The following considerations should be 

given when collecting native plant materials:

 · Number of parents. There is sufficient genetic research for woody forest species 

to recommend having a minimum of 20 unrelated seed parents represented in a 

collection in order to capture most of the genetic variation in a population. A similar 

number of individual parents should be included in cutting beds of clonally 

propagated species. Additional plant material would be needed if contribution 

by parents (of seeds or cuttings) is unequal. For dioecious species, attention to 

male-female ratios is essential to ensure adequate representation of both sexes. 

For species such as grasses, it is important to consult a geneticist familiar with those 

plant groups for guidance as to what an adequate parent population might be.

 · Source sites (stands). To represent the population of a seed zone well, seeds or 

cuttings should be collected from multiple sites within the zone. A similar numbers 

of parents should be sampled from each site. Seek out larger communities to help 

meet parent selection criteria.

 · Individual parents within a selected source. Individual maternal parents (seed 

trees) should be well separated from each other, yet not isolated from other trees. 

This will allow cross pollination by numerous paternal parents. A similar amount of 

seeds should be collected from each parent.
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Inset 6.2 – What To Do If There Are No Locally Adapted Native Seed 

Sources Available

(Adapted from Erickson and others 2003; Aubry and others 2005)

The volume of seeds needed for a revegetation project may not always be available in 

suffi cient quantities, particularly when plans have changed or the revegetation specialist 

has not been involved until the latter stages of the project. In these instances, there are 

three choices available to the revegetation specialist: 1) wait several years until the 

appropriate seeds are available; 2) use non-native cultivars or non-local native cultivars; or 

3) use introduced species that are non-persistent, non-invasive, or sterile.

Defer Seeding

If the appropriate species or seed sources are not available, then consider not seeding until 

the appropriate seeds become available. In the interim, soil cover for erosion control should 

be considered.

Non-Local Native Species

Native species that do not occur naturally in the local ecosystem, or native plant material 

that does not originate from genetically local sources, may be considered. These types of 

plant materials may include commercial cultivars. A cultivar is “a distinct, often intentionally 

bred subset of a species that will behave uniformly and predictably when grown in an 

environment to which it is adapted” (Aubry and others 2005). These cultivars are generally 

not preferable for wildland use due to concerns over adaptability, genetic diversity level, and 

the potential for genetic contamination, or “swamping,” of local native gene pools, including 

those of threatened, endangered, and sensitive plants (Millar and Libby 1989; Knapp and Rice 

1994; Linhart 1995; Montalvo and others 1997; Lesica and Allendorf 1999; Huff ord and Mazer 

2003). Because commercial cultivars are typically selected for agronomic traits, such as high 

fecundity, vegetative vigor, and competitive ability, their use may also adversely impact 

resident natural populations through direct competition and displacement. Moreover, 

cultivars of native species (and introduced look-alikes such as sheep fescue [Festuca ovina]) 

can be very diffi cult to distinguish from native germplasm. This could severely complicate 

eff orts to collect and propagate local material and waste valuable economic resources. 

Because of these concerns, cultivars should be used sparingly, with project objectives 

clearly understood. Consult with the seed producer or distributor before buying seeds and 

ask for the most appropriate cultivar for your area, where the source for the cultivar was 

collected (geographic location and elevation), and how many collections were made. The 

seeds should be certifi ed with a certifi cation tag attached to each seed bag. Tests for seed 

germination, purity, noxious weeds, and seeds per pound should be obtained.

Introduced Species

When appropriate seed sources are not available, sterile hybrids or annual/biennial/perennial 

introduced plant species that are non-persistent and non-invasive may be considered. 

Preferred non-native species are those that will not aggressively compete with the naturally 

occurring native plant community, invade plant communities outside the project area, 

persist in the ecosystem over the long term, or exchange genetic material with local native 

plant species. Some of these species include sterile hybrids, such as Regreen (a wheat x 

wheatgrass sterile hybrid) and annuals such as common oat (Avena sativa) and common 

wheat (Triticum aestivum). Exotic species that have not already been introduced into the area, 

or that have been found to be aggressive and/or persistent, should be avoided. Non-native 

species that were commonly used in the past should be avoided include Kentucky bluegrass 

(Poa pratensis), smooth brome (Bromus inermis), crested wheatgrass (Agropyron cristatum), 

orchardgrass (Dactylis glomerata), yellow and white sweetclover (Melilotus offi cinalis and 

M. albus), alsike clover (Trifolium hybridum), and alfalfa (Medicago sativa), to name a few. 

These species are generally no longer recommended due to their highly aggressive nature, 

resulting in widespread losses or displacement of native species and plant communities in 

western wildlands.
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acknowledge aspects of the revegetation process that are expected to develop naturally 

(Clewell and others, 2005).

However, if native seed regeneration is not suffi cient to revegetate the site, additional plant 

materials will need to be obtained and established. Plant materials may include:

 · Seeds,

 · Cuttings, and

 · Plants.

Determining which plant material to select for revegetation depends on the type of species 

being grown. For example, conifer trees have been shown to establish better and faster from 

plants than from seed or cuttings. On the other hand, grasses can be established from plants, 

but growing grass plants and planting them is very expensive compared to using seeds. Some 

species, however, do not produce reliable crops of seeds and therefore other plant materials, 

such as cuttings, will have to be used. Tables 6.3 and 6.4 compare the advantages and 

disadvantages of diff erent establishment methods and stocktypes. Various Implementation 

Guides (Chapter 10) describe obtaining plant materials in greater depth.

6.4.2.1 Seeds

Seeds are collected in the wild from native stands of grasses, forbs, shrubs, trees, and wetland 

plants. This plant material is used for seeding projects, such as hydroseeding of cut and fi ll slopes 

or other large areas of bare soil. Seeds of grass and forb species are best used for direct sowing, 

whereas seeds of shrubs and tree species are best used to grow nursery plants. If large amounts 

of grass or forb seeds are required for a project, seed collections can be increased through 

seed increase contracts. It can take up to three years to obtain enough seeds for a revegetation 

project – one year to collect the wild seeds and one to two years for seed increase. One of 

the advantages of utilizing seeds as the plant material is that seeding can be an inexpensive 

method of reestablishing plants for a large area. Guides to collecting wild seeds, increasing 

seeds, and salvaging and topsoil, duff , and litter are available in Chapter 10.

6.4.2.2 Cuttings

Cuttings are taken from stems, roots, or other plant parts and directly planted on the project 

site or grown into rooted cuttings at a nursery for later outplanting. Only a few species, such as 

willow (Salix spp.) and cottonwood (Populus spp.), can be easily established from direct sticking 

of cuttings on a project. Other species, such as quaking aspen (Populus tremuloides), can be 

established from cuttings in a controlled nursery environment, but not in the fi eld. Propagating 

plants from cuttings of most species is not possible under most growing conditions. Cuttings 

are collected in the wild in the winter months and either stored or immediately planted on the 

project. If large quantities of cuttings are required, cuttings can be propagated by growing 

them in stooling beds for several years at a nursery or other growing facility. Guides to working 

with cuttings are presented in Chapter 10.

6.4.2.3 Plants

Trees and shrubs are typically established using nursery stock rather than by direct seeding 

for several reasons. First, obtaining seeds from most tree and shrub species is expensive; in 

many years, they can be diffi cult to fi nd or collect. Second, shrub and tree seeds germinate and 

grow into seedlings at a slower rate than grass and forb species, giving them a disadvantage 

on the sites where grasses and forbs are present. Starting shrubs and conifers from large plants 

instead of seeds gives them a competitive advantage over grasses and forbs because roots are 

often longer and better developed, allowing access to deeper soil moisture. Grass and forb 

species are seldom established from nursery-grown plants because of the high cost. Exceptions 

are when grass or forb seeds are rare or hard to collect or increase; if species are diffi cult to 

establish from seeds on disturbed sites; or when the project requires restoring threatened or 

sensitive species.

Plants are typically grown in a nursery. However, for some projects, plants are salvaged from 

the construction site or adjacent areas. Sometimes salvaged plants are simply relocated quickly 

from one area to another. At other times, they may be transplanted into a nursery and replanted 

at a later time. Plants that are grown in a nursery require a lead time of one to two years from 

the time of ordering to availability. A variety of stocktypes are available from the nursery, 
Table 6.3 – Comparison of plant material types for revegetation planning (adapted from 

Dorner 2002).

Type Advantages Disadvantages

Balled-in-burlap

The plant is grown in the 

fi eld, dug up with its roots 

and surrounding soil, and 

wrapped in a protective 

material such as burlap.

• Well-developed root systems 

increase chances of survival 

on site 

• Provide shade and earlier 

establishment of upper 

canopy on site

• Expensive

• Large and heavy to transport

Bare-root

The plant is sold without any 

soil around its roots.

• Less expensive

• Easier to transport to site, 

lightweight to carry around 

for planting

• Roots have not been 

restricted by containers

• Require care not to let root 

systems dry out before 

planting.

• Diffi cult to establish in dry 

sites or sites with warm, 

sunny spring seasons.

Container

The plant is sold in a 

container of potting media or 

soil with drainage holes. Sizes 

and shapes of containers 

range from very small to 

very large.

• Well-established root 

systems with intact soil

• Provide “instant” plants 

on site

• Available in a variety of 

sizes, many are available 

year-round

• Can be planted all year long

• Native soil not used in 

nursery, transplant shock 

may occur when roots try to 

move into native soil

• Can be expensive

• Can be diffi cult to transport 

to and around site if large 

numbers are used

• Can be diffi cult to provide 

irrigation until established, 

may actually require more 

maintenance than plug

Liners/Plugs

A small plant, rooted cutting 

or seedling that is ready for 

transplanting. They are often 

used for herbaceous plants 

and grasses.

• Well-established root 

systems with intact soil.

• Easy to transplant, plant 

material pops out of 

containers easily

• Same as above

• Smaller plants may take 

longer to establish, require 

more initial maintenance

Cuttings

A piece of branch, root or 

leaf that is separated from a 

host plant and used to create 

a new plant. These may be 

placed in a rooting medium 

or stuck directly into the 

ground for planting.

• Inexpensive to produce; 

Cuttings may easily be taken 

on site or from nearby site 

• Easy and light to transport 

Known to work well in 

rocky areas or areas diffi cult 

to access

• No established root systems

• Timing of taking cuttings 

and planting them is 

important, varies among 

species limited to 

dormant periods

Salvage

Native plants that are 

removed from a site (to a 

nursery, storage area, or 

directly to another fi eld 

location) before ground 

disturbance at that site 

occurs. (Can also refer 

to salvaged cuttings or 

seed sources.)

• Can use plant material 

that would otherwise 

be destroyed

• Plant material could be local 

to site

• Relatively inexpensive

• Small or young salvage 

plants often adapt more 

readily to transplant than do 

mature specimens

• Diff erent native plants 

respond diff erently to being 

dug up, some loss could 

be expected

• Requires fairly intensive 

measures to protect plants 

and ensure they have 

adequate irrigation

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On-Site Methods

Characteristic Wild Cuttings Seeds Nursery Plants

Effi cient use of seeds 

and cuttings

N/A NO NO YES

Cost of establishment HIGH MODERATE LOW MODERATE

Ability to establish 

diffi cult species

YES NO NO YES

Option of using specifi c 

genotypes

NO NO YES YES

Precise scheduling of 

plant establishment

YES YES NO YES

Control of stand 

composition and density

YES YES NO YES

Matching stocktypes to 

site conditions

NO NO NO YES

Depletion of adjacent 

plant stands

YES YES NO NO

including small to very large plants; plants in containers or those without soil around the roots 

(bareroot); and plants grown in greenhouse environments or fi eld-grown plants (Figure 6.5). 

Selecting a stocktype will depend on the needs of the project, as there are multiple options for 

propagation and establishment, and many stocktypes to choose from.

For any stocktype, various desired characteristics should be defi ned including age, size, change 

of survival on the site, ability to compete with other vegetation and/or tolerate animal impacts; 

and methods that will be necessary to outplant and maintain the stocktype. For bareroot 

stocktypes, size, age, and potential survival rates should be considered. For cuttings, consider 

if the project requires containerized cuttings (with a root system in a container), heeled 

cuttings (with roots, but no container) or simply cuttings to stick directly in the ground on 

the project site. For cuttings, length, caliper, and issues of storage are also important factors. 

For container plants, no standard terminology exists for describing the diff erent types of 

container plants available (Landis and others 1992). They are usually described by their 

container type, referring to the volume and usually the shape of the container. Size and age of 

the plant is also described. When ordering container plants, consider age, caliper, height, root 

size and depth, and any other special characteristics that might help the plant survive in the 

fi eld (Table 6.3).

Salvaging plants from the project area can be an important component of protecting native 

plant diversity on the project site. Sometimes salvaged plants are simply relocated instantly 

from one area to another. Other times, they may be transplanted or moved to a nursery 

area, cared for, and then re-planted at an appropriate time. “Salvage” may also involve 

harvesting cuttings or seeds from plants that are going to be removed during the road 

construction process.

Depending on the species, genetics, site limiting factors, and specifi c project objectives, some 

idea of the appropriate “target” stocktypes will already be defi ned. For example, some plants 

respond well to certain propagation methods, some will be salvaged (“wildings”) from the 

site, and some are obvious candidates for direct seedling applications in order to facilitate fast 

regeneration. The needs and characteristics of a particular species will help determine if direct 

seeding, nursery propagation, or other methods are the more appropriate strategy. There are 

many options to consider. Some of these options are summarized in Table 6.4.

Table 6.4 – Comparison of diff erent plant establishment methods (adapted from Landis 

and others 1992).
39.37 inches 1meter

RL Supercell

D16 Deepot

Short One Treepot

Tall One Treepot

2 Gallon Treepot

PVC Tallpot

Ball-and-Burlap

Figure 6.5 – Nursery stock is available in many container 

sizes and shapes. Consider the advantages and drawbacks of 

diff erent options before ordering plants.

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6.4.2.4 Scheduling

Timing is a key factor for 

obtaining plant materials 

because many native plants 

or seeds are not widely 

available from nurseries and 

seed companies. Even if a 

species is available, the odds 

are that it is not from a local 

source that is genetically 

adapted to your project site. 

Therefore, the earlier you 

start planning the better. 

It usually takes a lead time 

of two to three years to 

administer seed collection, 

seed increase, and seedling 

propagation contracts. 

Sometimes you may need 

to allow three years to 

achieve suffi cient quantities 

of seeds. Plants (seedlings, 

cuttings, and so on) ordered 

from nurseries take a great 

deal of advanced planning 

for both seed collection 

and for plant propagation. 

Failure to realize the lead 

time necessary for seed 

collection and propagation 

of appropriate native plant 

materials is one of the most 

common mistakes made in 

revegetation projects.

6.4.3 Select Plant Material Installation and Maintenance Methods

There are many methods of installing plant materials on the project site. Seeds can be applied 

through hydroseeding equipment, disked or drilled into the soil surface, broadcast sown, 

imprinted, and/or covered with a variety of types of mulch. There are also a variety of techniques 

for installing cuttings and plants, including an expandable stinger (Figure 6.6), waterjet stinger, 

pot planter, auger, and regular old shovel. These methods are discussed in Chapter 10.

After plant materials have been installed, care is required until they are well-established. This 

includes protection from browsing animals, high temperatures, winds, competing vegetation, 

and drought. Measures that can be taken to mitigate for browsing animals include installing 

netting and tree shelters, as well as applying animal repellents. Seedlings can be protected 

from high temperatures and wind with shade cards, tree shelters, and large obstacles, such as 

logs. Competing vegetation is controlled through weeding, mulch, or herbicides. In extremely 

dry conditions, soil moisture can be supplemented by using irrigation systems.

6.4.4 Determine Outplanting Windows

In addition to ensuring you have enough lead time to successfully carry out native revegetation 

goals, you also need to determine the seasons for planting. There are advantages and 

disadvantages to carrying out operations at any time in the year and determining the timeframe 

should be based on the species, plant material, and site factors.

The optimum time of year to outplant for greatest plant survival is called the outplanting 

window. It is determined by graphing the annual precipitation, temperatures, and snow 

accumulation of a site. This information can be obtained from climate stations, as described in 

Phase One. Outplanting windows are also defi ned by the species, stocktype, and outplanting 
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% Survival of Transplants 50

60

80

70

90

40

30

20

10

0

Fall Planted

Spring Planted

A. richardsonii P. spicata

Figure 6.7 – Outplanting must be 

timed properly for best results given site 

conditions and species requirements 

(reproduced from Page and Bork 2005).

Figure 6.6 – Match stocktypes to outplanting options and equipment available. The 

expandable stinger (A) is a special planting machinery that attaches to the arm of an excavator. 

Long-tube stocktypes are placed in the stinger and pushed in the soil (B). The stinger opens and 

plants the seedling in the soil (C, D). This machinery can reach very steep, rocky slopes that are 

inaccessible for manual planting.

A

140

methods. For example, two diff erent species of bunch grass might have very diff erent survival 

rates depending on when they were outplanted. Figure 6.7 shows survival rates for bluebunch 

wheatgrass (Pseudoroegneria spicata), which survived better when planted in fall, and spreading 

needlegrass (Achnatherum richardsonii), which did better when planted in spring.

Several factors are important for determining outplanting windows. These include 1) soil 

temperatures in late winter and early spring, 2) precipitation during spring and early summer, 

3) soil temperatures in fall, 4) precipitation in fall, and 5) snow cover. Three examples of 

identifying outplanting windows are provided in Figures 6.8, 6.9 and 6.10. Applying the 

following set of guidelines to the climate data will help clarify the optimum times to plant.

6.4.4.1 Soil Temperatures in Late Winter and Spring

Seedlings must develop new roots soon after they are planted to become established and 

survive the hot (and in many regions, dry) summer of the fi rst growing season. For most species, 

new root growth occurs when soil temperatures exceed 42 °F. Waiting for soil temperatures to 

warm to 42 °F in the spring before outplanting, however, will shorten the period of time when 
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Spring

Planting

Window

6

5

4

3

2

1

0 0

10

20

30

40

50

60

70

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Average Rainfall (in)

Months

Average Temperature ( ̊F)

Fall

Planting

Window

Low Elevation Westside Cascades: Riddle, OR

Figure 6.8 – The project site 

is located near Tiller, Oregon, 

where winters are wet and 

relatively mild, and summers 

are dry and hot. North slopes 

support Douglas-fi r, incense 

cedar, and madrone. South 

slopes support ponderosa pine, 

oaks, and grasses. During the 

summer months, strong drying 

winds blow up the valley in the 

afternoon. Weather station 

records, from a U.S. Regional 

Climate Station located 

several miles away, show daily 

maximum summer temperatures in July and August averaging 84 °F.

The site has two planting windows. The spring planting window starts after the risk of the 

last winter cold front in mid-February has passed and ends two months before monthly 

precipitation dips below 1.5 inches. The fall planting window begins as soon as the fi rst fall rains 

wet the soil profi le and ends one month prior to soil temperatures dropping below 42 °F. 

Long dry summers, coupled with high temperatures and strong winds, create challenges 

to establishing seedlings. Outplanting in the fall or in mid to late winter is essential in order 

to develop new roots. Removing grass and other vegetation from around the seedling and 

applying a mulch fabric in March increases soil moisture. In places, tree shelters and shade cards 

placed around seedlings can protect them from the drying eff ects of the afternoon wind.

Hydroseeding in October with mulch and tackifi er will keep seeds in place long enough to 

germinate in November. Complete seedling establishment will occur by the following April.

Case Study: Low Elevation, Western Cascade Site
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Spring

Planting

Window

6

5

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1

0 0

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70

Eastside Cascade Site: Chiloquin, OR

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Average Rainfall (in)

Months

Average Temperature ( ̊F)

Snow Pack Snow Pack

Figure 6.9 – The climate at 

this project site is typifi ed by 

dry, mild summers and cold 

winters with a snow pack 

extending from late fall to 

late winter. (Climate data was 

from a weather station located 

near the town of Chiloquin, 

Oregon.) Ponderosa pine, 

quaking aspen, and bitterbrush 

are the dominant vegetation 

on the site. The planting 

window begins immediately 

after snowmelt. Precipitation 

drops off signifi cantly in April 

and May. Planting must be 

completed no later than 

the fi rst week of April when 

monthly precipitation drops 

below 1.5 inches. Note that soil temperatures during the recommended planting windows are 

cooler than 42 °F. Nevertheless, it is more important to plant early on arid sites than wait until 

soil temperatures warm. Rainstorms in the fall do not deliver enough moisture to recharge the 

soil before mean fall temperatures drop below 42 °F. Early planting can take place in the fall if 

seedlings are irrigated at the time of planting. Seedlings on south slopes should be mulched to 

conserve soil moisture, while seedlings on cooler north aspects would benefi t from, but may not 

require, mulch.

Grass and forb seeding in September and October is essential since most seeds from this 

area require a stratifi cation period. Seeds will not germinate in the fall because of the lack 

of continuous fall moisture and low temperatures. Germination occurs immediately after 

snowmelt in the spring. Seed germination can be poor because the soil surface dries out quickly 

due to low humidity, high solar radiation, and low precipitation. Mulching the seedbed with 

ground wood fi ber or straw will maintain high humidity around germinating seeds. Spring 

seeding can be successful if seeds are soaked for several days prior to seeding and if seeding is 

done as soon as snows have melted.

Case Study: Cool, Arid Site
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7

6

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80

High Elevation Site: Santiam Pass, OR

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Average Rainfall (in)

Months

Average Temperature ( ̊F)

Late Spring

Planting

Window

Late Summer

Planting

Window

Snow Pack Snow Pack

Figure 6.10 – This site is 

located in the high Cascade 

Mountains at 4,800 ft elevation. 

Mixed stands of mountain 

hemlock and noble fi r occupy 

the site. Snowpack begins in 

November and is present on the 

site until May, just as summer 

air temperatures increase. 

Seedlings must be planted as 

soon as the snow leaves the site. 

Thunder storms will typically 

wet the soil by late summer, 

opening a second planting 

window sometimes as early 

as late August. Competing 

vegetation must be controlled around container seedlings planted at this time to maintain 

high soil moisture for the remainder of the fall. Scalping vegetation immediately after planting 

and applying a mulch will help maintain high soil moisture. As temperatures begin to drop in 

late summer, evaporative demands on the planted seedlings are reduced. Planting must be 

completed by late September to ensure that seedlings will have some time to develop new roots. 

North sites will have cooler soil temperatures and should be planted sooner than south aspects.

Weather station data indicate average minimum air temperatures are cold during the growing 

season. Applying tree shelters around seedlings will increase daily air temperatures, creating a 

more favorable environment for seedling growth. North aspect seedling plantings might benefi t 

more from tree shelters than south aspect plantings.

Sowing can take place in the late spring, immediately after snowmelt, and again in the fall. 

Late spring sowing will be signifi cantly enhanced by applying mulch over the seedbed and/or 

pregerminating seed prior to sowing. Seeds of species that do not require stratifi cation should 

germinate within a month after sowing in late spring. Species requiring stratifi cation should be 

sown in the fall.

Case Study: High Elevation Site
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soil moisture is available to the seedling. For this reason, a common restoration strategy is to 

outplant seedlings as soon after the last threat of a deep frost in the winter has passed, even if 

the soil temperatures are below 42 °F. 

6.4.4.2 Precipitation in Spring and Summer

Much of the western United States experiences dry summers, with winters receiving most of 

the precipitation. Under this regime, soils lose their moisture in the summer and recharge from 

storms that occur in the fall and winter months. Plants have adapted to this climate by growing 

new roots and leaves during the spring, when soil moisture is high, and shutting down or 

becoming dormant in the summer, when soil moisture is depleted.

The most critical factor for seedlings that are outplanted in the spring is the length of time 

available for the seedling to develop new roots before soil moisture is depleted. Sites with little 

or no precipitation in the spring or summer will dry out faster than sites with high spring and 

summer precipitation. A rule of thumb is that an average monthly precipitation of less than 

1.5 inches will do little to recharge a dry soil during late spring through fall. Figures 6.8, 6.9, and 

6.10 show spring outplanting windows for three very diff erent project sites. On low elevation 

sites west of the Cascade Mountains, the planting window can be fall and spring (Figure 6.8), 

whereas high elevation sites might have a planting window only in late spring (Figure 6.10).

6.4.4.3 Soil Temperatures in Fall

If outplanting is planned for late summer or early fall, it is important that soils have high moisture 

and temperatures are warm enough to encourage new roots to grow into the soil before winter 

arrives. On cold sites where seedlings are not protected by snow, the upper portions of the 

soil profi le will typically freeze. Fall outplanted seedlings that have not established new roots 

below the frost line risk desiccation by wind or sun exposure in the winter months because 

no water is available to the seedling. For greatest success, soil temperatures should remain 

above 42 °F for at least one month after seedlings are planted in the fall for root development 

and seedling establishment prior to winter. Figure 6.10 shows a late summer planting window 

on a high elevation site where precipitation is high in September and soil temperatures are 

above 42 °F.

Soil temperatures are signifi cantly warmer on south aspects, which means that outplanting 

windows on south exposures are often wider and extend further into the fall than planting 

sites on north aspects, given soil moisture is adequate for root growth. Weather stations do 

not report soil temperatures. However, they can be extrapolated from average monthly air 

temperatures with a certain degree of reliability. Placing recording thermometers in the soil 

before construction will give more exact soil temperatures.

6.4.4.4 Precipitation in Fall

When outplanting seedlings in the fall, high soil moisture is essential for seedling survival and 

growth. Fall soil moisture is typically very low, and the only means of recharging a dry soil is 

through rainstorms or irrigation. Two or more inches of rain over a period of at least several days 

is often required to moisten most dry soils. Many sites in the western United States, however, 

seldom have rainstorm events great enough to moisten the top 12 inches of soil before cold 

soil temperatures occur. Fall planting on these sites has a low potential for seedling survival. 

On sites with suffi cient fall precipitation, planting windows are open as soon as a rainstorm 

event wets the surface 12 inches of soil.

6.4.4.5 Snow Cover

Seedlings should not be planted through snow, so outplanting windows are open before snow 

accumulation and after snowmelt. Be aware, however, that cold water from melting snow keeps 

soil temperatures low. Soil temperatures should be monitored during or following snowmelt.

6.4.5 Determine Sowing Windows

The outplanting windows for seed sowing may be diff erent than those for planting nursery 

stock. Optimum planting times for seeds are called “sowing windows.” Sowing windows change 

by site environment, sowing methods, and seed needs. Seeds will germinate and develop into 

healthy, viable plants when: 1) seed stratifi cation requirements are met, and 2) seeds are in a 

warm, moist environment during germination. Seed stratifi cation requires a cold, moist period, 
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ranging from a few weeks to several months, during which time the seeds are conditioned for 

germination. This usually occurs naturally in the western United States during the early to mid 

spring, but it can be induced artifi cially in seed coolers.

After seed stratifi cation requirements have been met, a moist, warm period must follow in which 

seeds and soil do not appreciably dry down. Drying during this time can prevent germination 

and kill new germinants. In the western United States, these conditions are best met by sowing 

seeds in the late summer to early fall. On warm, moist sites (e.g., Figure 6.8), seeds that require 

a very short stratifi cation period will germinate in the early fall and begin to establish ground 

cover before winter rains occur. Fall-sown seeds requiring stratifi cation will have moisture and 

temperature requirements met during the winter months. On drier sites (Figure 6.9), fall-sown 

seeds will not germinate due to lack of precipitation.

If fall sowing is not possible, sowing can take place in the late winter or early spring. Sowing 

at this time generally results in less vigorous stands of grass and forb seedlings because there 

is a shorter period of favorable conditions for seeds to germinate and seedlings to become 

established. Another drawback of spring sowing is that some species will not receive the 

required cold, moist period to break seed dormancy and germinate. Once germination has 

occurred, several months of periodic precipitation with average air temperatures exceeding 

40 °F are required for successful establishment of ground cover.

Spring sowing can be enhanced in several ways. A mulch applied over the seeds will help 

maintain higher seed moisture levels and keep soil moisture in the soil for a longer period. 

Seeds requiring stratifi cation can be artifi cially stratifi ed for spring sowing to achieve earlier 

germination (Cook and others 1997). Care must be taken that the seeds do not mold or begin 

to germinate during this period, or dry down for sowing. The eff ect of hydromulch equipment 

on germinating native species seeds is unknown at this time; seeds may be damaged if sown 

using this method.

6.5 NEXT STEPS

By the end of Phase Three, you will have completed an assessment and analysis of the native 

vegetation on your revegetation units and reference sites. You will have refi ned your DFCs for 

short- and long-term goals; gained an understanding of the species, plant communities, and 

successional processes; analyzed species and communities in order to select the species to be 

used for revegetation; and reviewed potential plant material types and seeding or outplanting 

methods to consider in order to revegetate the site. Now it is time to move to Phase Four, 

where all the elements will be integrated into a comprehensive strategy for road design, site 

treatments, and revegetation – the Revegetation Plan.
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7 PLANNING PHASE FOUR: INTEGRATE AND STRATEGIZE

7.1 INTRODUCTION

In Phase One of the planning process, project objectives were clarifi ed and revegetation units 

and reference sites were defi ned. Preliminary Desired Future Conditions (DFCs) were developed 

for each revegetation unit. During Phase Two, site attributes were defi ned, including limiting 

factors, options for mitigation, and available resources. In Phase Three, vegetation was analyzed 

to consider species, stocktypes, and plant establishment options. In Phase Four, the fi nal phase 

of planning, the work of all the previous phases is pulled together. Phase Four integrates the 

understanding of site limitations and resources, mitigation options, species, and seeding or 

outplanting methods into a comprehensive strategy for revegetating the site. This integrated 

strategy will culminate in the Revegetation Plan.

The steps for developing the revegetation plan in Phase Four are as follows:

 · Finalize revegetation units and DFCs,

 · Integrate survey information and develop potential revegetation strategies,

 · Compare and select revegetation strategies, and

 · Assemble plan.

A case study is provided to illustrate the thought process for the development and selection of 

revegetation strategies on a project.

7.2 FINALIZE REVEGETATION UNITS AND DFCS

Phase Four provides the opportunity to review, refi ne, and fi nalize revegetation units and the 

DFCs for each unit. The boundaries of revegetation units may be revised now that the sites have 

been more thoroughly surveyed. Additional ecological or management-based information 

may support creating additional revegetation units. Alternately, if management will be similar, 

an area originally divided into several revegetation units might be consolidated into one. Once 

the revegetation units are fi nalized, the DFCs for each unit can be fi nalized as well.

DFCs can be revised based on the information gathered during these assessments. For example, 

with more detail about the local native species and their specifi c requirements, some factors 

may emerge as less or more limiting for the species in your project. Water input might be low on 

the site. However, if native drought-tolerant (xeric) species abound, water will be less limiting 

for these species than if you were attempting to revegetate with more water-loving (mesic) 

species. It is possible that less mitigation for water will be necessary than originally assumed. 

The process of refi ning DFCs is essential in order to ensure that the objectives are feasible given 

the native species and ecological processes on the site.

Reference sites provided information on existing vegetation and illustrated what might 

happen on a site in one year, fi ve years, or several decades. These reference sites model how 

revegetation units might be expected to respond to change and management. The potential 

successional development of each revegetation unit should be reviewed. Asking what the 

revegetation units could look like in both short-term (1-3 years) and long-term (5, 10, 15+ years) 

timeframes is part of the process for fi nalizing DFCs.

An example of how DFC’s were developed for a project is described in Inset 7.1. In this case 

study several reference sites were selected, ranging from desirable to undesirable vegetation 

conditions. Defi ning site characteristics from a range of reference sites helped develop a 

realistic DFC for the project.

Site assessments that defi ne limiting factors for each revegetation unit in Phase Two become 

the basis for developing a revegetation strategy. For example, Figure 7.2 shows how limiting 

factors were summarized for a proposed project. By listing the limiting factors, the revegetation 

specialist can focus on only the most important site parameters requiring mitigation. Figure 7.3 

lists the potential mitigating measures available in this case study for each limiting factor. 
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7.3 INTEGRATE AND DEVELOP REVEGETATION STRATEGIES 

There are no “silver bullet” products or treatment methods that will transform a project 

site into a functioning plant community. A comprehensive understanding of the site 

and how revegetation treatments alone or in combination with other treatments will 

aff ect soil characteristics, plant establishment, and future successional processes is 

the key to successful revegetation. Several revegetation strategies can be developed 

for each revegetation unit by creating various combinations of mitigating measures. 

It is important to assess how these strategies compare with each other and how the 

combination of mitigating measures within a strategy will interact.

Strategies are often developed around major actions or themes. For instance, the 

three strategies in the case study shown in Inset 7.2 were based on mitigating for the 

lack of topsoil by:

 · Strategy 1: Adding fertilizer,

 · Strategy 2: Reapplying topsoil, and

 · Strategy 3: Blowing compost mulch.

These are very different approaches, and the resulting strategies will vary considerably.

Developing revegetation strategies is an integrative and collaborative process 

between vegetation and soils specialists and the project engineers. This requires 

a good understanding of the site limitations, site resources, and experience with 

a variety of mitigating measures. All reasonable possibilities should be considered 

before any are rejected.

7.4 SELECT A REVEGETATION STRATEGY

The spreadsheets shown in Figures 7.2, 7.3, and 7.4 are helpful in summarizing site 

attributes for defi ning limiting factors, keeping track of potential mitigating measures, 

and comparing revegetation strategies for each revegetation unit. Following this 

process can lead to an informed decision on selecting a revegetation strategy for 

each revegetation unit.

Figure 7.4 illustrates how strategies can be qualitatively compared. In this method, 

limiting factors are identifi ed for positive or negative eff ects on plant growth. Each of 

these characteristics is assessed for the conditions expected after construction with 

no mitigation measures employed, and qualitatively given a rating as follows:

- - - Severely limiting + Not limiting

- - Limiting + + Benefi cial

- Somewhat limiting + + + Very benefi cial

The selection of one strategy over others should be based on revegetation objectives 

and feasibility of applying the treatment, including considerations for economics, 

available skills, and resources. 

When selecting a strategy, both short-term and long-term planning are required. 

Mitigating limiting factors for long-term revegetation success however, does not 

always directly aid in early establishment of plant materials. Success during early plant 

establishment depends almost entirely on conditions in a narrow environment at the 

soil surface (six inches above and below the surface), while conditions must focus 

on soil quality at much deeper depths and aerial factors much higher than the soil 

surface. Until plants can grow out of this narrow surface zone, they will continue to be 

aff ected by climate extremes (moisture, temperature, and so on), competition, and 

animal damage. The fi rst few weeks after the installation of plant materials is often 

the most critical period in the revegetation process; plants should not be considered 

“established” until at least 1 to 2 years of growth. Developing revegetation strategies 

that meet both short and long-term revegetation goals is not always possible and 

there will be times when meeting short-term revegetation goals might have to give 

way to assuring long-term site recover.
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7.5 ASSEMBLE THE REVEGETATION PLAN

At the end of Phase Four, revegetation strategies for all revegetation units have been selected. If the 

planning process went well, writing the actual plan should simply be a compilation of the various 

strategies. Revegetation Plans vary in length and depth. At a minimum, a plan will typically include 

the following components:

 · Revegetation objectives,

 · Description and map of each revegetation unit;

 · Desired future conditions (DFCs) for each revegetation unit;

 · Analysis of site attributes (limiting factors and resources) and type of vegetation;

 · Description of mitigating measures;

 · Description of the revegetation strategy, including plant materials/stocktypes and 

application methods for each unit;

 · Key contacts and responsibilities;

 · Budget and timelines;

 · Strategies for monitoring achievement of DFCs; and

 · Strategies for correcting shortcomings based on monitoring information.

An example Revegetation Plan is provided in Chapter 8.

7.5.1 Networking

The revegetation plan is a valuable tool for communicating with the Federal Highway Administration, 

other government agencies, and the general public. The degree that a revegetation project 

succeeds is often proportional to the quality of these interactions. It requires identifying the agency 

players, aff ected or key community members, and local and regional workforce (See Chapter 2) and 

understanding their concerns. The best written plans are of little value if these relationships are not 

established and maintained. It is important to share versions of the plan with, and solicit input from, 

others involved in the project.

7.5.2 Timelines

From inception through implementation and monitoring, construction projects span many years. 

A timeline can help organize the series of steps required for a successful revegetation project, and 

should include all aspects and details of the project. The timeline is basically a “to do” list with 

corresponding “due dates.” Awareness of timing is crucial, especially when obtaining plant materials. 

More information on timelines is provided in the Implementation Guide to Obtaining Plant Materials 

(See Section 10.2).

7.5.3 Fiscal Concerns

Budgets are necessary to estimate costs. Methods to build budgets and timelines are outside the 

scope of this publication, but there are many resources available to assist with the process.

When the Planning Phase is complete, it will be time to move to the Implementation Phase. During 

implementation, the Revegetation Plan will be translated into task orders and prescriptions that 

specify how, when, where, and by whom the plan will be implemented.

7.6 NEXT STEPS

Phase Four, the fi nal phase of the planning process, integrates all the information gathered from 

the previous three phases. The understanding of limiting factors and resources, mitigation options, 

species, and planting methods are combined into a comprehensive strategy for revegetating the site. 

The steps of Phase Four are to: 1) fi nalize revegetation units and DFCs; 2) integrate survey information 

and develop potential revegetation strategies; 3) compare and select revegetation strategies; and 

4) assemble the plan. A case study with a decision matrix illustrates how to weigh various options and 

strategies to choose the most appropriate ones for the project. Phase Four culminates in the writing 

of the Revegetation Plan, which details the strategy and provides schedules and budgets for the 

project. The Revegetation Plan is an important tool for communicating with agencies, individuals, and 

the community about the project. An example Revegetation Plan is provided in the next chapter.
Inset 7.1 – Case Study – Defi ne Site, Limiting Factors, and Desired Future Conditions

Revegetation Unit Description

Five revegetation units were defi ned for this road project. The revegetation unit in this case 

study was defi ned from surveys of several reference sites and local reports.

Soils are generally deep sandy loams (less than 20% rock fragments) derived from pumice 

parent material. Topsoils are 6 to 8 inches deep. Duff and litter layers are 2 to 3 inches deep. 

Infi ltration rates are very high unless duff and litter layers are removed and soil is compacted. 

Slope gradients are less than 5H:1V, except for a few areas that approach 2H:1V. The climate 

is semi-arid, with an annual precipitation of 10 inches, delivered as snow in winter and 

intense thunderstorms in the summer months. Winters are very cold; summers are warm. 

Evapotranspiration rates are high from spring through fall. Vegetation on undisturbed 

reference sites is dominated by ponderosa pine, quaking aspen, bitterbrush, ceanothus, 

and Idaho fescue.

Disturbance Description

All vegetation will be removed and roots and 

stumps grubbed. Topsoil will be removed, 

leaving at least 2 feet of subsoil for rooting. 

Soils will be compacted, and the site is 

expected to appear similar to the photo of 

Reference Site 1 (Figure 7.1A).

Limiting Factors and Mitigating Measures

Figure 7.2 shows the potential limiting factors 

associated with this revegetation unit. Figure 

7.3 displays possible mitigating measures 

that could be employed to overcome 

each limitation.

Desired Future Condition

The revegetation objectives for this unit are 

to develop a low growing stand of native 

grasses and forbs that are not attractive as 

deer forage, exclude invasive weeds, and add 

visual interest to a high recreational use road. 

Based on reference sites or recently recovered 

disturbances, vegetative cover of a wellestablished grass and forb stand is 50% to 

70% in mid summer, with 10% to 30% bare 

soil. Vegetation establishment is very low the 

fi rst year, with less than 20% cover typically 

occurring. DFC thresholds after the fi rst year 

include: 20% vegetative cover, 30% bare soil, 

no knapweed. DFC thresholds after the third 

year include: 65% vegetative cover, 30% bare 

soil, no knapweed. Vegetative cover must be 

composed of 90% native vegetation.

Figure 7.1A – Reference Site 1. This site 

has been barren since construction. 

Soils are compacted and sheet erosion 

is active.

Figure 7.1B – Reference Site 2. This 

reference site is composed of squirreltail 

(Sitanion hystrix) and Oregon sunshine 

(Eriophyllum lanatum), representing the 

desired future condition of this project.

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and Strategize

Implementation

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Summary

1

Water

Input

Critical Plant

Factors Parameters Site Characteristics

2

Water

Storage

and

Accessiblity

3

Water

Loss

4

Nutrient

Cycling

5

Surface

Stability

6

Slope

Stability

7

Weeds

8

Pests

Precipitation

Interception

Infiltration

Road Drainage

Soil Texture

Rock Fragments

Soil Structure

Rooting Depth

Mycorrhizal Fungi

Wind

Aspect

Competing Vegetation

Soil Cover

Topsoil

Site Organic Matter

Nitrogen & Carbon

Nutrients

pH & Salts

Rainfall & Wind

Freeze-Thaw

Soil Cover

Surface Strength

Infiltration

Slope Gradient

Surface Roughness

Slope Length

Permeability

Restrictive Layer

Water Input

Slope Length

Slope Gradient

Soil Strength

Weed Sources

Growing Environment

Mammals

Insects

Diseases

Road Maintenance

Recreational Use

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

3” of rainfall in summer, thunderstorms July - Aug

none

low infiltration when compacted

none

low - sandy texture

relatively little gravels and no cobbles or rock

expected to be compacted

deep soils, but likely to be restricted by compaction

expected to be little to none

low - protected by surrounding forests

no southern aspects

little competing vegetation in first several years

low - high surface evaporation

none

very low

very low

very low

moderate pH, low salts

intense thunderstorms in summer, high rainfall splash

moderate to high when surface is compacted

low

low - no cohesion in sands

low

low slope gradients favorable to surface stability

expected to be rough

30 feet slope run, on compacted soils can get rills

low

NA

NA

NA

low slope gradients reduces risk of landslides

NA

populations of knapweed along road corridor

poor for weeds

deer populations in spring and fall; some gopher

minor

minor

some gravels from sanding roads - minimal effect

snowmobile traffic - minimal 

9 

Human

Interface

150

Figure 7.2 – Case Study – Defi ne limiting factors on the site.
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Introduction

Initiation

Planning

Phase IV: Integrate 

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Implementation

Monitoring

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Summary

1

Water

Input

Critical Plant

Factors Parameters Possible Mitigating Measures

2

Water

Storage

and

Accessiblity

3

Water

Loss

4

Nutrient

Cycling

5

Surface

Stability

6

Slope

Stability

7

Weeds

8

Pests

9 

Human

Interface

Precipitation

Interception

Infiltration

Road Drainage

Soil Texture

Rock Fragments

Soil Structure

Rooting Depth

Mycorrhizal Fungi

Wind

Aspect

Competing Vegetation

Soil Cover

Topsoil

Site Organic Matter

Nitrogen & Carbon

Nutrients

pH & Salts

Rainfall & Wind

Freeze-Thaw

Soil Cover

Surface Strength

Infiltration

Slope Gradient

Surface Roughness

Slope Length

Permeability

Restrictive Layer

Water Input

Slope Length

Slope Gradient

Soil Strength

Weed Sources

Growing Environment

Mammals

Insects

Diseases

Road Maintenance

Recreational Use

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

irrigate, deep sow, mulch, high density sowing

deep tillage, harrow, disk, mulch

compost, clay

deep tillage, compost, topsoil

deep tillage, compost

topsoil addition, mycorrhizal inoculum

mulch, deep sow

topsoil addition, manufactured topsoil

incorporated litter duff, mulch, logs

nitrogen-fixing species, topsoil, fertilizers, compost

topsoil, fertilizers, compost

mulch

mulch

mulch

mulch, tackifier

disk, harrow, compost

reduce slope length

prevent and control, quick native revegetation

sow non-palatable or non-desirable species

151

Figure 7.3 – Case Study – List possible mitigating measures for limiting factors.
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Inset 7 .2 – Case Study – Design Potential Revegetation Strategies

From the list of possible mitigating measures, design several revegetation strategies.

Strategy 1

· Subsoil till the top two feet of soil to break up compaction.

· Fertilize with a slow-release fertilizer.

· Use working group of nitrogen-fixing species (lupine, ceanothus and bitterbrush) 

and hydroseed in fall with wood fi ber mulch.

Short-term and long-term eff ects

Subsoil tillage reduces compaction and increases surface stability by roughening the 

surface, increasing infi ltration and reducing freeze-thaw potential. Subsoil tillage also 

increases rooting depth.

Fertilizers will provide nitrogen and other nutrients for seedling establishment. Suffi cient 

nitrogen may not be present to meet vegetation cover thresholds, but higher nitrogen 

levels in the soil might encourage annual weed growth.

Emergence of sown seeds could be poor, especially if there are periods of dry spring 

weather during germination. Surface soil holds very little moisture in exposed, dry areas, 

and the wood fi ber in the hydromulch will not provide enough moisture around seeds for 

germination. Mycorrhizal inoculum is important on dry sites, but has not been added to the 

hydroseed mix. This could result in poor establishment of seedlings.

Discussion

This is the least expensive strategy, and the least likely to create conditions for long-term 

revegetation. Nevertheless, the deep, non-compacted soils, though lacking in organic 

matter, should be able to support a good stand of nitrogen-fi xing species. This could restore 

nitrogen to the soil and build soil biomass over time.

Strategy 2

 · Salvage and reapply 6 to 9 inches of topsoil, then subsoil till to 24 inches.

 · Apply seeds through hydroseeding equipment and cover with an application of 

straw mulch and tackifi er.

 · Use a working group of visually pleasing species (predominately showy 

forb species).

Short-term and long-term eff ects

Topsoil will increase the water-holding capacity in the surface soil, as well as rooting 

depth, nutrients, organic matter, infi ltration rates, and mycorrhizal inoculum. Knapweed 

(Centaurea spp.) infestation is possible if care is not taken to avoid areas of knapweed during 

soil salvage operations. Long-term nitrogen needs for the site are met with the additions 

of topsoil, but short-term nitrogen availability for seedling establishment might be low. 

Subsoil tillage increases rooting depth, surface stability through surface roughening, and 

infi ltration. Tillage also reduces the freeze-thaw potential. Application of straw will increase 

germination and early seedling establishment due to higher humidity around seeds during 

germination. Straw also protects the soil surface from rainfall splash during thunderstorms. 

Straw can be a source of weeds if certifi ed straw has not been purchased.

Discussion

This is the most expensive measure, but will potentially support the highest amount of plant 

cover over the long-term. All major limiting factors have been mitigated in this strategy.

Strategy 3

 · Apply 2-inch layer of compost to soil surface using a compost blower. 

 · Apply seeds and mycorrhizal inoculum during this operation. 

 · Use a working group of visually pleasing species (predominately showy 

forb species).
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Short-term and long-term eff ects

Soil moisture is increased around the seeds due to the higher water-holding capacity of 

compost. Seeds are buried during compost blowing, increasing the chances of germination 

and establishment. Smaller seeds buried under the deeper thicknesses of compost will have 

poor emergence. Nutrients are supplied through the compost for short- and long-term 

plant community needs. Nutrients are not as accessible on the surface of the soil, requiring 

a portion of the grass and forb root systems to be growing into the compost. Mycorrhizal 

fungi are supplied through commercial inoculum. Soils are still compacted, limiting 

rooting depth.

Discussion

This strategy should be adequate to establish plants. Since soils are still compacted, meeting 

long-term vegetative cover targets might be diffi cult. This strategy could be improved if the 

compost were applied to previously tilled soil, or applied to the surface and then tilled into 

the soil to mix the compost and loosen the soil.

SELECT REVEGETATION STRATEGY

Comparing the revegetation strategies with their eff ects on the limiting factors of the site, a 

selection of the most appropriate revegetation strategy can be made.

Since the amount of topsoil was of limited supply for the project, Strategy 2 (topsoil 

placement) was selected for the gentler terrain where it could be easily placed. Strategy 

3 (mulch application) was selected for the steeper gradients. Strategy 1 was not selected 

because it was the least likely to meet the revegetation objectives (DFCs) of the project.
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Precipitation

Interception

Infiltration

Road Drainage

Soil Texture

Rock Fragments

Soil Structure

Rooting Depth

Mycorrhizal Fungi

Wind

Aspect

Competing Vegetation

Soil Cover

Topsoil

Site Organic Matter

Nitrogen & Carbon

Nutrients

pH & Salts

Rainfall & Wind

Freeze-Thaw

Soil Cover

Surface Strength

Infiltration

Slope Gradient

Surface Roughness

Slope Length

Permeability

Restrictive Layer

Water Input

Slope Length

Slope Gradient

Soil Strength

Weed Sources

Growing Environment

Mammals

Insects

Diseases

Road Maintenance

Recreational Use

1

Water

Input

2

Water

Storage

and

Accessiblity

3

Water

Withdrawal

4

Nutrient

Cycling

5

Surface

Stability

6

Slope

Stability

7

Weeds

8

Pests

 low

 low

none

 low

 low

none

none

none

none

mod-high

 low

 low

deer use

 

Critical Plant

Factors Parameters No Action 1 2

Strategies

3

9 

Human

Interface

- - + + -

- - + +

- - + +

- - - - - - + + - - -

- - - - ++

- - - - + + +

- + + +

- - + 

+ 

-

+ 

+

- - + + + + + +

- - - - + -

- - - - - - - - - - - -

Figure 7.4 – Case Study – Compare revegetation strategies. Evaluate each strategy 

using a qualitative system for comparison.

154
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SUNRIVER TO MT. BACHELOR

DRAFT REVEGETATION PLAN

MARCH 2006

OR PFH 244-1(1)

Deschutes National Forest

Deschutes County

Oregon

8 REVEGETATION PLAN EXAMPLE
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BACKGROUND

This revegetation plan outlines the basic actions that will be taken by the USDA Forest 

Service in association with Western Federal Lands Highways Division (WFLHD) of the Federal 

Highway Administration (FHWA) to revegetate the Sunriver to Mt. Bachelor Highway project 

[OR PFH 244-1(1)]. Construction is scheduled to begin in spring 2006, with revegetation 

implementation to begin in fall 2006.

The Sunriver to Mt. Bachelor project is located entirely on the Bend/Fort Rock Ranger District, 

Deschutes National Forest in Central Oregon.

ROLES, RESPONSIBILITIES, AND CONTACTS

The entire project is bordered by National Forest lands. The environmental specialist will be the 

main contact during the planning phase. During construction, the project engineer will be the 

main contact. After the project has been completed, the county engineer and environmental 

specialist will be the contacts.

The project as planned (see Sunriver to Mt. Bachelor Highway Environmental Assessment) will 

minimally aff ect soil conditions along the roadway. Cuts and fi lls will be designed to minimize 

erosion. The erosion and sediment control plans will be developed by the WFLHD and will 

be the responsibility of the contractor. The Forest Service will have a limited role, primarily 

in providing guidance for temporary stabilization practices. Key to this guidance will be the 

selection of appropriate materials and methods that will not deter future revegetation eff orts.

REVEGETATION OBJECTIVES

The following revegetation objectives were addressed in the Environmental Analysis (EA) for 

cuts, fi lls, and abandoned roads:

 · Enhance scenic beauty using native grass, forb, shrub, and tree species;

 · Control noxious weeds using only EA approved herbicides and native grass and 

forb species;

 · Maintain slope stability using native grass, forb, and shrub species;

 · Minimize soil erosion with native grass, forb, shrub, and tree species; and

 · Maintain biodiversity of the surrounding plant communities by planting locally adapted 

native species.

Table 8.1 – Project contacts.

Contact Organization Phone E-mail Role

Jim Scott USDA Forest Service FS Agreement Liaison

April Jones USDA Forest Service Lead Revegetation Specialist

Jill Smith USDA Forest Service Revegetation Specialist

Adam Riles Deschutes National 

Forest

Local FS Liaison and Permitting Specialist 

(Bend/Fort Rock District)

Carlos 

Escobar

FHWA Project manager – general FHWA project 

oversight. 

Lindsey 

Chen

FHWA Project Engineer

Sam James FHWA Design Engineer

Philip West FHWA Environmental Specialist – agreement 

coordinator, main contact between FHWA 

and other regulatory agencies, including 

DEQ and EPA

Carol Clint Deschutes County – Director of Public 

Works
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The revegetation objectives for the source and waste areas are for suitable native grass and 

forb vegetation for erosion control and wildlife forage.

PROJECT CONSTRAINTS

The following are the major anticipated constraints to successful revegetation:

 · Limited topsoil;

 · Wind at higher elevations;

 · Frost pockets;

 · Hot, dry south slopes in summer;

 · Animal damage – gophers and deer;

 · Noxious weeds – spotted knapweed (Centaurea maculosa);

 · Non-native invasive species – mullein (Verbascum thapsus);

 · Threatened and endangered plants – greentinge Indian paintbrush (Castilleja 

chlorotica);

 · Covering of plants with gravel applied to roads in winter;

 · Herbicides – limited chemicals and NEPA cleared sites;

 · Oversteepened slope gradients;

 · Snow damage from plowing/blowing accumulation;

 · Winter desiccation; and

 · Driving on obliterated roads.

LAWS, REGULATIONS AND POLICIES

Following Forest Service National Policy, only genetically appropriate, locally adapted native 

plant materials will be used in the revegetation of this project.

Laws governing surface water quality are not major constraints on this project, since there 

are no perennial or intermittent streams, lakes, or wetland areas within the project area or 

adjacent areas.

Table 8.2 – Collection, propagation, and revegetation schedule.

Project Size

Length: 21.7 km (13.5 mi)

Area: 16.6 ha (41 ac)

Activity Timeline 2004 2005 2006 2007 2008 2009 2010 2011

Seed collections X X

Seed increase X X X

Cuttings collection X X 

Cuttings/container 

plants, stool-beds

XXX

Hydroseeding X

Plant shrubs/trees X X

Monitor X X X X
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Table 8.3 – Cost and production schedule of plant materials.

 Schedule/Nursery Cost/lb Total 

lb

Total 

Cost

1. Seed Needed 

Grasses

ACOCO (Achnatherum occidentale 

ssp. occidentale)

Collected – sown for production fall 2004 – 

Currans

$22.50 31 $697.50

BRMA4 (Bromus marginatus) Collect 2005 – sown for production fall 2005 

– Currans

$5.19 159 $825.21

ELEL5 (Elymus elymoides) Collected – in production – Currans $19.75 102 $2,014.50

FEID (Festuca idahoensis) Collected – stored for district $11.00 200 $2,200.00

Forbs 

ERBL2 (Ericameria bloomeri) Collect 2005 ?? $50.00 2 $100.00

ERLA6 (Eriophyllum lanatum) Recollect 2005 – will sow for production – 

Lucky Peak

$50.00 100 $5,000.00

IPAGA3 (Ipomopsis aggregata ssp. 

aggregata)

Collected – in production – Stone $50.00 20 $1,000.00

LUAR3 (Lupinus argenteus) Collected – sown for production fall 2004 – 

Lucky Peak

$50.00 60 $3,000.00

LULE2 (Lupinus lepidus) Collect 2004/5 – will sow for production – 

Lucky Peak

$50.00 53 $2,650.00

PECI2 (Penstemon cinicola) Not propagated – failed in production 

PEEU (Penstemon euglaucus) Collected (in production) – Stone $50.00 25 $1,250.00

PEHU (Penstemon humilis) Collected – in production – Stone $50.00 12 $600.00

PHHA (Phacelia hastata) Recollect 2005 – sown for production fall 2005 

– Lucky Peak

$50.00 12 $600.00

Shrubs 

ARNE (Arctostaphylos nevadensis)* Collected (DGRC) $100.00 1 $100.00

ARPA6 (Arctostaphylos patula)* Collected (DGRC) $100.00 1 $100.00 

CEVE (Ceanothus velutinus) Collected (DGRC) $200.00 2 $400.00

PUTR2 (Purshia tridentata) FS seed bank (Bend) $35.00 1 $35.00

Trees 

ABCO (Abies concolor) FS seed bank (DGRC) $265.00 0.5 $132.50 

PIAL (Pinus albicaulis) FS seed bank (DGRC) $265.00 0.5 $132.50 

PICO (Pinus contorta) FS seed bank (Bend) $265.00 1 $265.00 

PIMO3 (Pinus monticola) FS seed bank (DGRC) $265.00 0.5 $132.50 

PIPO (Pinus ponderosa) FS seed bank (Bend) $265.00 1 $265.00 

Schedule/Nursery Cost/

Plant

No. of 

Plants

Total 

Cost

2. Shrub Cuttings

ARNE (Arctostaphylos nevadensis) 

(short one treepots)*

Fall 05/Spring 06 (DGRC) $2.50 320 $800.00

ARPA6 (Arctostaphylos patula) 

(short one treepots)*

Spring 06 (DGRC) $2.50 320 $800.00

3. Container Plants (Native spp.)

ARNE (short one treepots) Spring 06 (DGRC) $3.50 320 $1,120.00

ARPA6 (short one treepots) Spring 06 (DGRC) $3.50 320 $1,120.00

CEVE (short one treepots) Spring 06 (DGRC) $2.00 395 $790.00

PUTR2 (D40) Spring 06 (DGRC) $2.00 67 $134.00

4. Conifers 

ABCO (short one treepots) Spring 06 (DGRC) $2.00 160 $320.00

PIAL (D25) Spring 06 (DGRC) $1.00 43 $43.00

PICO (1 gal) Sow Spring 05/Xplant Spring 06 (Stone) $4.00 301 $1,204.00

PICO (Q-plug+1) Spring 06 (Stone) $0.50 1375 $687.50

PIMO3 (D25) Spring 06 (DGRC) $1.00 87 $87.00

PIPO (1 gal) Sow Spring 05/Xplant Spring 06 (Stone) $4.00 53 $212.00

PIPO (Q-plug+1) Spring 06 (Stone) $0.50 1097 $548.50

Total disturbed area = 16.6 ha (41 ac)

* A total of 640 plants each for ARNE and ARPA6 are needed. Both seedlings and cuttings will be attempted to fulfi ll 

this order.
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NOXIOUS WEEDS

Prevention

As stated in the EA, the contractor will be required to clean all equipment and vehicles 

before entering and leaving National Forest lands to minimize spread of state- and countylisted noxious and non-native plants. Mud, dirt, and plant parts will be removed from project 

equipment before moving equipment into project areas. Also, the contractor will be required 

to use gravel from a known weed-free site. Both Deschutes Bridge and Dutchman Pits were 

found by Forest Service personnel to be free of noxious weeds. Any other potential sources will 

have noxious weed surveys completed before being used. The contractor will be responsible 

for environmental clearance on other potential sites. The contractor will be required to monitor 

and fl ag the known knapweed sites, and remove any plants before project work begins. The 

Forest Service has record of known knapweed sites and will supply this information to the 

contractor. The contractor will be required to use weed-free staging areas. Vehicles or heavy 

equipment will not be allowed to park, or be staged at the junction of FS Roads 40 and 41, 

or at the junction of FS Road 45 and Oregon Highway 372, where there are known noxious 

weed sites.

Control

Monitoring and treatment of noxious weeds and invasive plants will occur regularly beginning 

in 2004 and will continue through successful vegetation establishment. The monitoring and 

treatment plan will be cooperatively developed by WFLHD, FS, and County staff with the FS as 

lead agency. The plan is not a substitute for prevention, but rather directs and funds additional 

resources to monitor and treat noxious weeds and invasive plant species in, and adjacent to, 

the construction corridor during and after project implementation. Monitoring also includes 

haul roads and source and waste areas.

PROPOSED REVEGETATION SCHEDULE

PLANT MATERIALS

Locally-collected plant materials will be obtained under the guidance of the Forest Service 

district botanist through seed collection contracts. Seed increase will be accomplished over 

a 3- to 4-year period using the regional seed increase contract. The following table gives a 

general schedule and rough estimate of cost of plant production.

OVERALL MONITORING

Monitoring will be conducted during late spring to early summer of the fi eld season following 

the initial seed application. Areas of unsatisfactory plant establishment will be evaluated for 

retreatment and will be re-seeded, if appropriate, the following fall. Shrubs and trees will be 

assessed for establishment rate, survival, animal damage and need for protection, and potential 

need for replacement with new plants. Monitoring will continue over a period of 3 years to 

evaluate success in establishment, species composition, and percentage of plant cover. Noxious 

weeds will also be monitored for a minimum of 3 years, and will be eradicated if found on 

the site. “Soil cover” and “species presence” monitoring protocols will be used.

REVEGETATION UNITS

Five revegetation units plus source and waste areas were delineated for this project based on 

vegetation and soil fi eld surveys. Subunits within 4 of the 5 units were delineated based on 

special treatment needs. The revegetation plan was developed based on existing disturbed, 

disturbed and recovered, and undisturbed reference sites for plant communities.

Climate

The project crosses through several distinct climate zones, often defi ned by distinct 

plant communities:

Lower Elevations (Revegetation Units 1, 2, 3). The beginning of the project (1,290 to 1,440 m 

[4,235 to 4,730 ft] elevation) has a climate similar to the towns of Bend or Sisters. The data 
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20 Jan Feb Mar Apr May Jun Jul

Months

Temperature (  ̊F)

Aug Sep Oct Nov Dec

30

40

50

60

70

80

90

Max Min

Bend

Sisters

Santiam Pass

Figure 8.2 – Minimum and maximum temperatures for areas surrounding revegetation sites.

Sisters, OR

Bend, OR

Santiam Pass

(Crest of Cascades)

Jan Feb Mar Apr May Jun Jul

Months

Precipitation (inches)

Aug Sep Oct Nov Dec 0

2

4

6

8

10

12

14

16

Figure 8.1 – Precipitation for areas surrounding revegetation sites.

160

collected at the weather stations in these towns show scant precipitation distributed relatively 

evenly throughout the year (Figure 8.1) with total annual rainfall between 12 and 14 in (30.5 and 

35.5 cm). Typically, the melting snowpack recharges the soil profi le in the spring; once plants 

become active, this moisture can become depleted quickly. Soil moisture is a limiting factor 

and seedling establishment should be approached with several objectives: 1) minimize soil 

moisture losses from evaporation by using surface mulch where possible; 2) keep competing 

vegetation away from planted seedlings by using surface mulch; 3) use deep-rooted, large 

container stock; 4) utilize two potential planting windows – in the fall after signifi cant rains, 

or in the spring immediately after snowmelt and the soils are thawed. (Do not wait for higher 

soil temperatures.)

Snowpack is often gone by late winter. Frozen soils can extend into early spring. Soils must not 

be frozen when seedlings are planted.

The lower elevations have distinctly warmer daily temperatures than higher elevations; 

minimum daily temperatures are very similar (Figure 8.2). Microclimates created by landforms 

can make some portions of the lower elevations as cold as, or colder than, the higher elevations. 

Revegetation Unit 2, for example, sits on a fl at with poor air fl ow. Cold area settles into this 

area creating an inversion or frost pocket. Where lodgepole pine is the dominant or only tree 

species present in an area, it is often an indicator that the site is very cold. In areas where the 

road traverses cinder cones or on gently sloping terrain, the air fl ow is greater, and minimum air 

temperatures are not as cold, nor is duration as long.

Lack of a continuous snowpack and the very cold temperatures on some sites can create 

problems for fall-planted trees. Trees that are planted in the fall will be subjected to extremely 

cold temperatures if they are not covered by snow. This can be a problem with newly planted 
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seedlings, especially during periods where soils are frozen and desiccating winds are high. 

Therefore, seedlings should be planted in late winter and early spring on these sites. Seeds can 

be sown either in the fall or early spring. If the seeds are sown in the early spring, they should be 

stratifi ed for the required period before sowing and covered with a seedbed mulch or soil.

Higher Elevations (Revegetation Units 4 and 5). The revegetation units at the higher elevations 

(1,440 to 1,645 m [4,730 to 5,400 ft]) are greatly infl uenced by snowpacks. On typical years, 

snow has accumulated by November and can last into April or May. Snowpacks often insulate, 

or moderate, ground temperatures. Therefore seeds or seedlings placed in the fall can be 

protected from extreme temperatures and wind by a deep snowpack. Seeds that are sown in 

the fall and covered with a snowpack are protected, stratifi ed, and ready to germinate as soon 

as the snowpack has melted. If conditions are right, soils might not freeze under a snowpack and 

seedlings can grow roots during late winter to early spring (observed at Chiloquin Highway). 

The preferred period for sowing seeds and planting seedlings at these higher elevations is 

in fall.

At higher elevations, high winds can restrict plant establishment, especially in Revegetation 

Unit 5. Without protection, tree establishment may be diffi cult. Planting seedlings behind 

down, woody material such as logs can help protect seedlings during establishment. Using 

tree shelters can also protect the seedlings from wind desiccation and should be considered 

on these sites.

Extreme surface temperatures are encountered on south slopes, especially in the spring. 

Temperature readings from iButton® data loggers (Maxim Integrated Products, Sunnyvale, CA) 

placed near the intersection of FS roads 45 and 46 showed daily temperatures close to 100 °F 

(38 °C). High temperatures can create very harsh conditions for seed germination. On these 

sites, mulch should be considered. Shredded wood fi bers will have stability on south slopes 

and create favorable conditions for seed germination.

On steep north slopes, soils thaw much later than south slopes. Soil moisture is maintained longer 

on north slopes, so soils are more prone to the eff ects of freeze-thaw cycles or frost heaving. 

On steep slopes, this can make the surface soil very unstable. Seeds that are in the process 

of germinating on these sites will move downslope. One option is the application of surface 

mulch that would stabilize the surface so seeds can germinate in a more stable seedbed.

Soils 

Soils are derived from pumice parent material. These soils are unique in that they have low 

bulk densities, are single-grained, and have low cohesion. Since these soils are derived from 

recent volcanic activity, they are young with very little development. Nutrient levels are in the 

lower ranges for plants. In many areas, the soils are deep, equating to a high moisture supply 

for seedlings with deep roots.

Soil Nutrients: Table 8.4 shows four sites where topsoil will be removed, stored, and reapplied. 

Samples were taken uniformly from the 1 to 23 cm (0.4 to 9.0 in) surface horizon and represent a 

composite sample of soils. These results show the soils have low coarse fragment composition 

with loamy sand texture, a mildly acid pH (6.1 to 6.4), and low salt levels. Organic matter is 

between 3% and 4%, which is acceptable; total N is low for forest lands. Calcium and boron are 

low, and fertilizers or soil amendments containing these elements could be benefi cial to plant 

growth. Soil testing should be done in reference areas and during construction to determine 

soil amendment rates.

Fertilizing: Commercially available fertilizers (nitrogen, potassium, and phosphorus) are 

unnecessary on abandoned road sites where trees are planted. Species such as lodgepole 

pine require very little nitrogen. On sites where mulch is being applied, nutrients should be 

available as the mulch decomposes. Application of mycorrhizal fungi, either at the nursery or in 

the planting hole, will assure that the seedlings are well colonized with appropriate benefi cial 

fungi. This will help increase seedling access to soil water and nutrients. If seedlings show 

nutrient defi ciencies at a later point in their development, fertilizers can be surface-applied 

around each seedling instead of broadcast.

For sites to be seeded, fertilizers can be benefi cial. However, high applications of fast-release 

fertilizer in the fi rst year (e.g., ammonium nitrate) can encourage the establishment of weedy 

or undesirable plants. Therefore, seeds should be sown in the fi rst year without fertilizers and 

allowed to become established. Slow-release fertilizers can be applied in spring of the following 
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year based on soil analysis. Products such as Biosol® and Fertile Fiber are good products to use. 

Since the disturbed sites on this project will be low in nitrogen, applying as much nitrogen 

by the second or third years, in this form, could be benefi cial to establishing long-term native 

plant communities. Higher application rates of slow-release fertilizers are possible on the 

low elevation sites because lower precipitation presents less likelihood of deep leaching of 

nitrogen. Also, cold soil temperatures throughout much of the year mean the slow-release 

fertilizers will not decompose as fast and release nutrients. As the slow-release fertilizers break 

down, nutrients are taken up by the well-established native plants that convert the readily 

available nutrients into biomass, boosting nutrient cycling.

Topsoil Storage: It will be necessary to ensure that topsoil is free of seeds from undesirable 

vegetation. When possible, schedule work to accommodate the following:

 · Topsoils are stockpiled when dry;

 · Storage periods are kept to a minimum;

 · Stockpiles are protected from becoming wet in the winter; and

 · Weed establishment around stockpiles is avoided.

Covering the piles with plastic will help keep piles from becoming wet, and also prevent 

weed establishment. When reapplying topsoil, avoid mixing the topsoil with any of the 

subsoil material.

Revegetation Unit 1

Description – This unit is 2,600 m (8,535 ft) in length – between stations 0+200 and 2+810 

and located from 1,290 to 1,320 m (4,235 to 4,340 ft) elevation on a south aspect. Vegetation 

consists of ponderosa (Pinus ponderosa) and lodgepole pine (P. contorta) with a bitterbrush 

(Purshia tridentata) understory. The main revegetation unit consists entirely of minor cut and 

fi ll slopes, where the cuts predominately have slopes of 1V:3H and the fi lls have slopes of 1V:4H. 

The cut and fi ll slopes total approximately 16,700 m2 (4.1 ac).

Site Limitations – Summer conditions are hot and dry, and evapotranspiration is high. The soil 

is loamy sand, which has low water-holding capacity, and can be hydrophobic in the summer. 

Gophers may be a problem.

Revegetation Objectives – Revegetation objectives are visual to blend with the surrounding 

forest stands and openings.

Treatments – This unit should become revegetated fairly quickly. A mix of species, including 

squirreltail (Elymus elymoides), western needlegrass (Achnatherum occidentale), Pacifi c lupine 

(Lupinus lepidus), silverleaf phacelia (Phacelia hastata), and rabbitbrush (Ericameria bloomeri) 

will be seeded. Scarlet gilia (Ipomopsis aggregata) and glaucous beardtongue (Penstemon 

euglaucus) may be added to the mix on the larger, more visible cut slopes. For gentle slopes 

(1V:5H or less), the seed mix will be applied with ground-based spreaders and covered with soil 

in late fall. The method to cover seeds will be determined later.

On all steep cut and fi ll slopes, hydroseeding (using the same seed mix) with 2,000 lb/ac mulch 

and tackifi er will be applied in early fall.

This unit also contains 3 special subunits requiring additional treatments (Table 8.5).

Subunit 1.F.1. The majority of the fi ll will receive the same treatment as the overall Unit 1. The 

bottom of the fi ll, beginning 18 m (60 ft) from the road centerline, will be planted with Q-plug+1 

ponderosa pine with a spacing of 3 x 3 m (10 x 10 ft) in a natural random pattern.

Subunit 1.A.1. This unit is a decommissioned road with only 1 entrance onto the main road. 

Once the road surface has been removed and subsoiled, planting islands will be established 

to blend with the surrounding forest type. Approximately 8 cm (3 in) of (contractor-supplied) 

mulch will be applied in 6 m (20 ft) diameter islands (approximately 14.5 m3 [19 yd3] of material 

per unit 1.A.1). Following mulch application, ponderosa pine will be planted into the established 

planting islands. The trees will be a combination of larger potted (4 l [1 gal]) trees at the entrance 

into the road, and smaller (Q-plug+1) trees throughout the rest of the unit.

Subunit 1.C.1. The majority of the cut will receive the same treatment as the overall Unit 1. 

Beginning 14 m (45 ft) from the road centerline, approximately 8 cm (3 in) of mulch will be 

applied to the cut slope (approximately 46 m3 [60 yd3] of material). Bitterbrush grown in 
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Soil Parameter Test Units 20+960 18+800 18+640 14+620

Site Condition Undisturbed Undisturbed Undisturbed Undisturbed

Sampling Depth cm 1-23 1-23 1-23 1-23

Texture estimated USDA loamy sand loamy sand loamy sand loamy sand

Rock Fragments sieve % 15 15 15 15

pH saturated paste 6.4 6.1 6.4 6.2

Bulk Density estimated gr/cc 0.9 0.9 0.9 0.9

Salts (uS/cm) saturated paste uS/cm 0.75 0.74 0.66 0.6

C:N calculated 20 26 23 21

Sol. Ca:Mg calculated 0.86 1.49 0.00 0.76

Fe:Mn calculated 11.50 7.66 4.30 8.24

Organic Matter % 3 4.1 4.4 3.7

lbs/ac 135,441 163,326 175,277 147,392

Total C LECO % 2 2.91 3.39 2.55

lbs/ac 80,000 116,000 135,000 101,000

Total N LECO % 0.1 0.11 0.15 0.12

lbs/ac 398 438 597 478 

Available N 

(nitrate)

2N KCl extract mg/kg 2.49 2.68 2.33 3.44

lbs/ac 10 11 9 14

% Nitrate Release calculated 2.513 2.511 1.508 2.929

Total P Olsen NaHCO3 mg/kg 5.3 5.1 9.8 5.5

lbs/ac 21 20 39 22

Available K saturated paste 2.9 1.96 4.9 4.9

lbs/ac 12 8 20 20

Total K Olsen NaHCO3 mg/kg 58 47 105 96

lbs/ac 231 187 418 382

Available Ca saturated paste mg/l 0.3 0.7 0 0.34

lbs/ac 1.2 2.8 0 1.4

Available Mg saturated paste mg/l 0.35 0.47 0.45 0.45

lbs/ac 1.4 1.9 1.8 1.8

Available Na saturated paste mg/l 8.77 11.4 8.46 9.76

lbs/ac 35 45 34 39

Available S saturated paste mg/l 0.75 1.54 0.98 1.09

lbs/ac 3 6.1 3.9 4.3 

Sulfate S Olsen NaHCO3 mg/l 17.10 15.50 13.00 1.45

lbs/ac 68 62 52 6

Available B saturated paste mg/l 0.02 0.02 0.01 0.02

lbs/ac 0.10 0.10 0.00 0.10

Zinc Olsen NaHCO3 mg/l 0.31 0.36 0.81 0.41

lbs/ac 113 2

Table 8.4 – Soil test results for four undisturbed sites that are proposed topsoil sources.
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D40 DeepotTM containers will be out-planted into this area with a 3 x 3 m (10 x 10 ft) spacing 

(avoiding grid planting).

Desired Future Condition – Native grass and forb species will occupy 15% of ground cover 

12 months after seeding and over 40% after the second year. NPDES permit requires establishment 

of plant ground cover of at least 70% of the surrounding natural vegetative cover.

Approximately 12 months following road decommission, the conifer seedlings will have been 

planted on the abandoned road area at a rate of approximately 445 trees/ac (1,100 trees/ha), 

with heavier concentrations at the beginning of the decommissioned road. At the end of 5 years, 

this area should have an overall tree stocking at a minimum 250 trees/ac (620 trees/ha).

Monitoring Protocol – Photopoint monitoring will be conducted in the fall of the fi rst and third 

years following seeding throughout the main unit.

Survival on the planted subunits will be monitored within planting islands. Ten percent of 

planting islands will be monitored in the fi rst, third, and fi fth years.

Noxious weeds will be monitored for a minimum of 3 years and will be eradicated if found on 

the site.

Data Gaps – Do we need mulch to germinate and establish seedlings? Test in 2004 did not 

show a diff erence.

Does wood straw or shredded wood fi ber increase surface moisture during germination, 

therefore increasing germination and establishment?

Does time of sowing make a diff erence in germination and establishment? Current practice is 

fall sowing. Would stratifi ed seeds hydroseeded in spring establish as well or better than fall?

Revegetation Unit 2

Description – This unit is 7,400 m (24,280 ft) in length – between 2+800 and 10+200, and located 

from 1,320 to 1,365 m (4,340 to 4,480 ft) elevation on a mostly fl at gradient. The vegetation 

consists of lodge-pole pine and small amounts of ponderosa pine, with bitterbrush and 

glaucus penstemon predominating in the understory. The stands are mixes of regeneration 

cuts, openings, and islands of dense lodgepole pine. The main revegetation unit consists of 

minor cut and fi ll slopes, where the cuts have slopes of 1V:2H to 1V:3H and the fi lls have slopes 

of 1V:4H. The cut and fi ll slopes total approximately 35,040 m2 (8.7 ac).

Site Limitations – The soil is loamy sand, which has low water-holding capacity and can be 

hydrophobic. Summer conditions are warm and dry. The unit has defi nite low-lying frost 

pockets. Gophers may be a minor problem.

Considering the high recreational use in this area, establishment of vegetation on the 

abandoned road areas may be diffi cult. Any forest opening on the Deschutes will become 

heavily used by off -highway vehicles (OHVs) and snowmobiles, which will impede survival and 

establishment of vegetation in these areas.

Revegetation Objectives – The Sunriver to Mt. Bachelor highway is used most heavily for 

recreational traffi c during both the summer and winter seasons. Revegetation objectives are 

visual – that is, to maintain a grass and forb community to blend with the surrounding forest 

stands and openings. In addition, the reclaimed road bed should contain the same species mix 

(both overstory and understory) as the surrounding forest stands.

Desired Future Condition – Approximately 12 months following road reconstruction, a mix of 

low-growing grass and forb species will have begun to establish throughout the main unit. The 

same mix will be present at the end of 3 years. NPDES permit requires establishment of plant 

ground cover of at least 70% of the surrounding natural vegetative cover.

Approximately 12 months following road decommission, a mix of conifer and shrub species 

will have been planted on the abandoned road area at a rate of approximately 1,010 trees/ac 

(2,500 trees/ha) overall, with heavier concentrations of conifer species at each end of the 

decommissioned road. At the end of 5 years, this area should contain the same mix of species, 

with overall tree stocking at approximately 500 trees/ac (1,240 trees/ha).

Treatments – Due to the possibility of frost pockets and the hydrophobic soils, this area may 

be somewhat slower to revegetate than unit 1. Squirrel tail, western needlegrass, prairie lupine, 

glaucous penstemon, and golden rabbitbrush will be seeded onto this unit. Scarlet gilia, Oregon 
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sunshine (Eriophyllum lanatum), and/or silvery lupine (Lupinus argenteus) may be added to the 

mix on the larger cut slopes. For all slopes less than 1V:3H slopes, the seed mix will be applied 

and harrowed in late fall. Shredded wood mulch without tackifi er or compost may be used on 

some of the larger fi ll slopes.

On slopes greater than 1V:3H, hydroseeding (using the same seed mix) with 1,000 lb mulch and 

tackifi er will be applied in late fall. Since wind is not a large factor in this area, some smaller cut 

slopes may be hydroseeded without mulch or tackifi er.

This unit contains 1 special subunit requiring additional treatments (Table 8.6).

Unit 2.A.1. This unit is a large section of decommissioned road with 3 entrances onto the 

main road. Once the road surface has been removed and subsoiled, planting islands will be 

established to blend with the surrounding forest type. Approximately 8 cm (3 in) of (contractorsupplied) mulch will be applied in 6 m (20 ft) diameter islands (approximately 112 m3 [146 yd3] of 

material). Following mulch application, a mix of lodgepole and ponderosa pine will be planted 

into the unit. The trees will be a combination of larger container (4 l [1 gal]) trees at the entrance 

into the road, and smaller (Q-plug+1) trees throughout the rest of the unit. Heavier planting 

will occur at the beginning and end of the decommissioned areas. All planting will mimic the 

surrounding stand mosaic, and will not resemble a grid planting.

Monitoring Protocol – Photopoint monitoring will be conducted in the fall of the fi rst and third 

years for cut and fi ll slopes. Survival on the planted subunits will be monitored within planting 

islands. Ten percent of planting islands will be monitored in the fi rst, third, and fi fth years.

Noxious weeds will be monitored for a minimum of 3 years and will be eradicated if found on 

the site.

Data Gaps – Eff ectiveness of using wood straw or mulch without tackifi er with native species 

seeds on the east side of the Cascades is unknown. Eff ectiveness of hydroseeding without 

mulch with native species is unknown.

Revegetation Unit 3

Description – This unit is 2,900 m (9,510 ft) in length – between 10+200 and 12+100 and located 

from 1,365 and 1,440 m (4,480 to 4,730 ft) elevation on south- to southwest-facing slopes. This 

area is a warmer site than revegetation unit 1 or 2, with better air drainage, and is located at 

the base of a cinder cone. The overstory is ponderosa pine and small amounts of lodgepole 

pine, with bitterbrush, snowbrush ceanothus (Ceanothus velutinus), and greenleaf manzanita 

(Arctostaphylos patula) in the understory. The revegetation unit consists entirely of cut and fi ll 

slopes. The cuts have slopes of 1V:2H to 1V:3H and the fi lls have slopes of 1V:4H. The cut and fi ll 

slopes total approximately 8,260 m2 (2 ac).

Site Limitations – Summer conditions are hot and dry, and evapotranspiration is high. This unit 

is located at the base of a cinder cone, and there are large outcroppings of lava rock.

Revegetation Objectives – The Sunriver to Mt. Bachelor highway is used most heavily for 

recreational traffi c during both the summer and winter seasons. Revegetation objectives are 

visual – that is, to maintain a grass, forb, and shrub community to blend with the surrounding 

forest stands and openings.

Desired Future Condition – Approximately 12 months following road reconstruction, 

a mix of low-growing grass and forb species within 10 m (30 ft) of the road edge, and a mix 

of taller forbs and shrubs from 10 to 20 m (30 to 65 ft) from the road edge will have begun 

Table 8.5 – Special subunits for Revegetation Unit 1.

Subunit # Location Predominant 

Landform

Approximate 

treatment 

area (m2) 

Approximate 

treatment 

area (ac)

1.F.1 0+280 to 0+360 Fill slope 400 0.10

1.A.1 0+580 Abandoned road 700 0.17

1.C.1 1+500 to 1+600 Cut slope 600 0.15
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to establish throughout the unit. The same mix will be present at the end of 3 years. NPDES 

permit requires establishment of plant ground cover of at least 70% of the surrounding natural 

vegetative cover.

Treatments – None of the fi ll or cut slopes are particularly large, and the unit should be 

revegetated by the local seed bank fairly quickly. Hydroseeding will be minimal, and only a 

small number of species will be included in this mix. The mix should include squirrel tail, Idaho 

fescue (Festuca idahoensis), glaucous penstemon, and golden rabbitbrush for this unit. For fi ll 

slopes, the seed mix will be applied and harrowed in late fall. Hydroseeding will occur on cut 

slopes, but mulch or tackifi er may not be necessary due to lack of wind through this area.

Monitoring Protocol – Photopoint monitoring for soil cover will be conducted in the fall of the 

fi rst and third years for cut and fi ll slopes.

Noxious weeds will be monitored for a minimum of 3 years and will be eradicated if found on 

the site.

Data Gaps – Eff ectiveness of using hydroseeding without mulch or tackifi er with native species 

seeds on the east side of the Cascades is unknown.

Revegetation Unit 4

Description – This unit is 4,200 m (13,780 ft) in length between stations 12+100 and 16+300, 

and located from 1,440 to 1,584 m (4,730 to 5,200 ft) elevation. The unit is somewhat colder 

than unit 3, with the overstory consisting of a mix of ponderosa and lodgepole pine, with 

bitterbrush, ceanothus, greenleaf manzanita, and wax currant (Ribes cereum) predominating in 

the understory. The revegetation unit consists cut and fi ll slopes and 3 sections of abandoned 

road. The cuts have slopes of 1V:2H to 1V:3H and the fi lls have slopes of 1V:4H. The cut and fi ll 

slopes total approximately 34,760 m2 (8.6 ac).

Site Limitations – Summer conditions are hot and dry, and evapotranspiration is high. 

The topsoil is thin in many areas, with bedrock close to the surface and many lava outcrops.

Considering the high recreational use in this area, establishment of vegetation on the 

abandoned road areas may be diffi cult. Any forest opening on the Deschutes will become 

heavily used by OHVs and snowmobiles, which will impede survival and establishment of 

vegetation in these areas.

Revegetation Objectives – The Sunriver to Mt. Bachelor highway is used most heavily for 

recreational traffi c during both the summer and winter seasons. In addition, this unit contains 

the area around Edison Butte Sno-Park, which is heavily used for hiking and cross-country 

skiing. Revegetation objectives are visual – that is, to maintain a grass, forb, and shrub 

community to blend with the surrounding forest stands and openings. The reclaimed road 

beds should contain the same species mix (both overstory and understory) as the surrounding 

forest stands.

Desired Future Condition – Approximately 12 months following road reconstruction, a mix 

of low-growing grass and forb species will have begun to establish throughout the unit. 

The same mix will be present at the end of 3 years with better coverage. NPDES permit 

requires establishment of plant ground cover of at least 70% of the surrounding natural 

vegetative cover.

Within 12 to 18 months following road decommission, a mix of conifer and shrub species will 

have been planted on the abandoned road areas. Depending on the subunit, initial stocking 

will range from 445 to 1,010 trees/ac (1,100 to 2,500 trees/ha), with heavier concentrations of 

Table 8.6 – Special subunit for Revegetation Unit 2.

Subunit # Location Predominant 

Landform

Approximate 

treatment 

area (m2) 

Approximate 

treatment 

area (ac)

2.A.1 3+300 to 3+550 Abandoned road 3,900 0.96
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conifer species at each end of the decommissioned roads. At the end of 5 years, this area should 

contain the same mix of species, with overall tree stocking ranging from 250 to 500 trees/acre 

(620 to 1,240 trees/ha).

Treatments – This unit may require more time to regenerate because it is somewhat colder 

than the previous units, and contains a mix of plant associations. Both cut and fi ll slopes will 

be hydroseeded with 1,000 lb mulch and tackifi er; wind is an issue in this area. Since this area 

includes the Sno-Park, which receives somewhat heavier use in the summer, the hydroseed mix 

will be slightly diff erent than the other units – that is, it will include a few more forb species for 

visual enhancement. The seed mix will include squirreltail, western needlegrass, prairie lupine, 

silvery lupine, white leaf phacelia, glaucous penstemon, and Oregon sunshine. Hayblowing 

with squirrel tail may also be used on the fi lls.

This unit contains 7 special subunits requiring additional treatments (Table 8.7).

Unit 4.A.1. This unit is a decommissioned road that will run beside the main road. Once the 

road surface has been removed and subsoiled, planting islands will be established to blend 

with the surrounding forest type. Approximately 8 cm (3 in) of contractor-supplied mulch will 

be applied in 6 m (20 ft) diameter islands (approximately 21 m3 [27 yd3] of material). Following 

mulch application, ponderosa pine (Q-plug+1) will be planted into the unit.

Unit 4.A.2. This unit is a decommissioned road with 2 entrances onto the main road. Once the 

road surface has been removed and subsoiled, planting islands will be established to blend 

with the surrounding forest type. Approximately 8 cm (3 in) of (contractor-supplied) mulch will 

be applied in 6 m (20 ft) diameter islands (approximately 17.5 m3 [23 yd3] of material). Following 

mulch application, a combination of ponderosa pine (q-plug+1) and ceanothus (D60 DeepotTM 

plugs) will be planted into the unit.

Unit 4.A.3. This unit is a decommissioned road with 2 entrances onto the main road. Once the 

road surface has been removed and subsoiled, planting islands will be established to blend 

with the surrounding forest type. Approximately 8 cm (3 in) of contractor-supplied mulch will 

be applied in 6 m (20 ft) diameter islands (approximately 86 m3 [112 yd3] of material). Following 

mulch application, a combination of lodgepole and ponderosa pine and ceanothus will be 

planted into the unit. The trees will be a combination of larger potted (4 l [1 gal]) lodgepole 

pine trees at the entrance into the road, and smaller lodge-pole and ponderosa pine (Q-plug+1) 

trees and ceanothus (D60 DeepotTM) throughout the rest of the unit with an approximate 3 x 3 m 

(10 x 10 ft) spacing for the trees and 2 x 2 m (6.6 x 6.6 ft) spacing for the ceanothus (avoiding 

grid planting).

Unit 4.C.1. This unit is a larger cut slope below a clearcut. The soil is shallow granitic, with bedrock 

close to the surface. The majority of the cut will receive the same treatment as the overall Unit 4. 

Beginning 18 m (60 ft) from the road centerline, ceanothus grown in D60 DeepotTM containers 

will be out-planted into this area on approximately 3 x 3 m (10 x 10 ft) spacing.

Unit 4.A.4. This unit is a decommissioned road with 2 minor entrances onto the main road 

(but with the reclaimed area running fairly close to the new road). Once the road surface has 

been removed and sub-soiled, planting islands will be established to blend with the surrounding 

forest type. Approximately 8 cm (3 in) of (contractor-supplied) mulch will be applied in 6 m 

(20 ft) diameter islands (approximately 21 m3 [28 yd3] of material). Following mulch application, 

a combination of ponderosa pine (Q-plug+1) trees and ceanothus (D60 DeepotTM plugs) will be 

planted throughout the unit.

Unit 4.F.1. This unit is a large fi ll section. The majority of the fi ll will receive the same treatment 

as the overall Unit 1. The bottom of the fi ll, beginning 18 m (60 ft) from the road centerline, will 

be planted with ceanothus (D60 DeepotTM plugs) on approximately 3 x 3 m (10 x 10 ft) spacing.

Unit 4.A.5. This unit is a visible decommissioned road with 2 highly visible entrances onto the 

main road. The small stand of lodgepole pine should be maintained between the new and old 

road. If possible, the stand should be thinned, mulched, and fertilized for the fi rst 1 to 2 years to 

encourage growth for visuals. Once the road surface has been removed and subsoiled, planting 

islands will be established to blend with the surrounding forest type. Approximately 8 cm (3 in) of 

(contractor-supplied) mulch will be applied in 6 m (20 ft) diameter islands (approximately 97 m3

[127 yd3] of material). Following mulch application, a combination of lodgepole and ponderosa 

pine will be planted into the unit. The trees will be a combination of larger potted (4 l [1 gal]) 

lodgepole pine trees at the entrance into the road, and smaller lodgepole and ponderosa pine 
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(Q-plug+1) trees throughout the rest of the unit. Use of larger trees transplanted with a tree 

spade may be considered for the decommissioned “entrances” for this unit.

Monitoring Protocol – Photopoint monitoring will be conducted in the fall of the fi rst and 

third years following seeding throughout the main unit. Survival on the planted subunits will 

be monitored within planting islands. Ten percent of planting islands will be monitored in the 

fi rst, third, and fi fth years.

Noxious weeds will be monitored for a minimum of 3 years and will be eradicated if found on 

the site.

Data Gaps – Eff ectiveness of using hydroseeding and mulch with native species seeds on the 

east side of the Cascades is unknown.

Revegetation Unit 5

Description – This unit is 5,423 m (17,800 ft) in length – between 16+300 and 21+723 and located 

from (1,585 to 1,645 m (5,200 to 5,400 ft) elevation. The overstory species in the unit grade from 

a mix of ponderosa and lodgepole pine, through an area containing ponderosa, lodgepole, 

western white (Pinus monticola), and whitebark (P. albicaulis) pines, mountain hemlock (Tsuga 

mertensiana), white fi r (Abies concolor), and subalpine fi r (A. lasiocarpa), to the higher elevation 

portion containing subalpine fi r and lodgepole pine. The understory vegetation grades from 

ceanothus, greenleaf manzanita, and wax currant to pinemat manzanita (Arctostaphylos 

nevadensis), Carex inops, and bottlebrush squirreltail (Elymus elymoides). The revegetation 

unit consists of cut and fi ll slopes and 2 sections of abandoned road. The cuts predominately 

have slopes of 1V:2H to 1V:3H and the fi lls have slopes of 1V:4H. The cut and fi ll slopes total 

approximately 46,660 m2 (11.5 ac).

Site Limitations – Summer conditions are hot and dry, and evapotranspiration is high. 

The topsoil is thin in many areas, with bedrock close to the surface. The higher elevation 

portions of the unit (close to the upper end of the project) are subject to wind damage.

Considering the high recreational use in this area, establishment of woody vegetation on the 

abandoned road areas may be diffi cult. Any forest opening on the Deschutes will become 

heavily used by OHVs and snowmobiles, which will impede survival and establishment of 

vegetation in these areas.

Revegetation Objectives – The Sunriver to Mt. Bachelor highway is used most heavily for 

recreational traffi c during both the summer and winter seasons. Revegetation objectives 

are visual – that is, to maintain a grass and forb community to blend with the surrounding 

forest stands and openings. In addition, the reclaimed road bed should contain the same 

species mix (both overstory and understory) as the surrounding forest stands. NPDES permit 

requires establishment of plant ground cover of at least 70% of the surrounding natural 

vegetative cover.

Table 8.7 – Special subunits for Revegetation Unit 4.

Subunit # Location Predominant 

Landform

Approximate 

treatment 

area (m2) 

Approximate 

treatment 

area (ac)

4.A.1 14+260 to 14+350 Abandoned road 540 0.13

4.A.2 14+470 to 14+560 Abandoned road 720 0.18

4.A.3 14+600 to 14+860 Abandoned road 3,000 0.74

4.C.1 14+800 to 14+840 Cut slope 320 0.08

4.A.4 15+200 to 15+300 Abandoned road 1,000 0.25

4.F.1 15+700 to 15+840 Fill slope 840 0.21

4.A.5 16+150 to 16+420 Abandoned road 4,050 1.00
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Desired Future Condition – Approximately 12 months following road reconstruction, a mix of 

low-growing grass and forb species will have begun to establish throughout the main unit. The 

same mix will be present at the end of 3 years at higher coverage.

Approximately 12 months following road decommission, a mix of conifer and shrub species 

will have been planted on the abandoned road area at a rate of approximately 445 trees/ac 

(1,100 trees/ha) overall, with heavier concentrations of conifer species at each end of the 

decommissioned roads. At the end of 5 years, this area should contain the same mix of species, 

with overall tree stocking at approximately 250 trees/ac (620 trees/ha).

Treatments – This unit may require a longer period to regenerate. It is colder than the previous 

units, and contains a mix of plant associations. Both cut and fi ll slopes will be hydroseeded with 

1,000 lb/ac mulch and tackifi er, since wind is an issue in this area. The hydroseed mix will be 

slightly diff erent than the other units. The seed mix will include squirrel tail, mountain brome 

(Bromus carinatus), silvery lupine, glaucous beardtongue, and silverleaf phacelia. If it is possible 

to use chopped pieces of Carex inops roots, this species will be included in the hydroseeding 

mix. Hayblowing with squirrel tail may also be used on the fi lls.

Monitoring Protocol – Photopoint monitoring will be conducted in the fall of the fi rst and 

third years following seeding throughout the main unit. Survival on the planted subunits will 

be monitored within planting islands. Ten percent of planting islands will be monitored in the 

fi rst, third, and fi fth years.

Noxious weeds will be monitored for a minimum of 3 years and will be eradicated if found on 

the site.

Data Gaps – Eff ectiveness of using hydroseeding and mulch with native species seeds on the 

east side of the Cascades is unknown. Eff ectiveness of spreading Carex spp. root systems via 

hydroseeding is unknown.

Note: The Forest Service is responsible for the revegetation of both source and waste areas 

associated with the project. Upon fi nal selection of these areas, a revegetation plan will be 

formulated specifi cally for each selected site in accordance with environmental conditions.
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Project 

Phase

SubPhase Cost CategoryPerson 

Days

Cost 

per Day

Total 

Cost

Planning

I. Pre-fi eld project orientation and 

planning: reviewing PIR, map-making, 

research & development contacts, 

project assignments

5 $300.00 $1,500.00

II. Field visits, scheduled meetings, 

Forest staff time, technology/product 

research. Travel, walk site, source and 

waste areas, locate reference sites 

develop species list, map noxious 

weeds, identify potential collection 

sites, water sources for hydroseeding.

20 $300.00 $6,000.00

III. Synthesize fi eld data, develop 

site recommendations and draft 

revegetation prescriptions, develop 

timeline and make plans for seeds

10 $300.00 $3,000.00

IV. Arrange for seed collections and 

propagation

3 $300.00 $900.00

V. Finalize revegetation plan 8 $300.00 $2,400.00

Plant

Materials

I. Oversee seed collection/

procurement, seed increase and 

seedling production

8 $300.00 $2,400.00

II. Seed purchase (see plant material 

costs table)

 $25,845.00

III. Seedling purchase (see plant material 

costs table)

 $9,500.00

IV. Mulch purchase/application ($40/

application yd3 x 863)

 $34,520.00

Implementation/ 

Monitoring

I. Final site assessment/evaluation 1 $300.00 $300.00

II. Storage, transport and staging of 

plant materials

 $1,000.00

III. Application/planting costs

a) Hydroseeding ($3,000/ac x 35 ac) $70,000.00

b) Hand planting shrubs and trees 

($2.00/plant x 4,860)

 $9,720.00

c) Field contract administration 30 $300.00 $9,000.00

IV. Monitoring 

a) Establishment phase 10 $300.00 $3,000.00

b) Eff ectiveness phase 10 $300.00 $3,000.00

c) Noxious weeds 5 $300.00 $1,500.00

d) Final report 3 $300.00 $900.00

V. Administrative oversight 6 $400.00 $2,400.00

Total Cost

I. Total Days Budgeted 119

II. Total Salary $36,300.00

III. Vehicle costs ($10/day + $0.445/mi) $3,800.00

I V. Misc. materials and supplies $1,500.00

 V. Per Diem (70 days x $150) $10,500.00

VI. Revegetation Cost $202,685.00

VII. Total Revegetation Cost w/ overhead $205,077.00

Table 8.9 – Revegetation cost estimates for Sunriver to Mt. Bachelor project.
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9 IMPLEMENTATION

9.1 INTRODUCTION

A successful revegetation project requires not only good planning, but eff ective implementation 

of the plan. The Initiation Phase of this report (Chapters 2 and 3) described the organizations, 

decision processes, and technical concepts involved in beginning a roadside revegetation 

project. The Planning Phase (Chapters 4 through 7) culminated in the Revegetation Plan, 

combining strategies for mitigating limiting factors, utilizing site resources, and revegetating 

the site. Now, in the Implementation Phase, the plan will unfold in the fi eld.

The shift from the Planning Phase to the Implementation Phase involves a change in 

approach. The planning process tends to be orderly and systematic, with the planner able to 

take an idealized bird’s eye perspective of how the project might best proceed. In contrast, 

implementation is approached from the ground up, and requires fl exibility and adaptability 

in order to fulfi ll the objectives of the plan while working with the unpredictable realities of 

the fi eld.

While the plan guides the project, few projects are implemented exactly as planned. Each project 

is unique, with its own set of issues and challenges. Schedules and supplies change, unforeseen 

circumstances intrude, and new opportunities emerge. Teamwork, cooperation, and eff ective 

communication with project managers and inspectors will enable the revegetation specialist 

to utilize all available resources to make the revegetation plan successful. Good planning 

and a systematic approach to implementation lay the groundwork to acquire necessary 

materials to revegetate the site, including services, seeds, topsoil, and nursery-grown plants. 

In the Implementation Phase, fl exibility, adaptability, and creativity in obtaining and installing 

these materials will be important. For example, seed mixes, application rates, and installation 

methods might have to be modifi ed due to new information or unforeseen circumstances. 

Lessons learned can lead to new and innovative approaches to revegetation.

The tasks for successfully implementing a revegetation plan are to:

1) Review plans with construction engineer,

2) Review revegetation treatment details and timelines,

3) Develop contracts,

4) Install treatments,

5) Keep good records,

6) Carry out quality control, and

7) Implement early maintenance and monitoring.

This chapter is a general overview of the implementation process. Following this chapter, 

Implementation Guides provide details on the key factors to consider, including soil and site 

treatments, obtaining plant materials, and installing and caring for plants.

9.2 REVIEW PLANS WITH CONSTRUCTION ENGINEER

The Initiation Phase highlighted the key working relationships for the revegetation specialist 

to develop during the revegetation process. For some projects, the same engineer will be the 

contact from project inception through its completion. For more complex projects, the design 

engineer may hand off the road plans for the construction engineer to implement. Regardless, 

the engineer who will be on-site during road construction is an essential relationship for 

implementing a successful revegetation plan. A relationship with both staff s is essential. 

The design engineer will assure that revegetation plans are designed into the construction 

plans, schedules, materials lists, and so on. The construction engineer, who will be on site 

during all phases of road construction, will interpret and implement designs with the input 

and interpretation of the revegetation specialist. Complex designs, such as soil-faced gabion 

walls, planting pockets, plantable rockeries, and so on, require more involvement from 

all participants.

The construction engineer can greatly facilitate all aspects of revegetation by providing 

construction timelines by road segment, modifi cations, updates, site specifi c information, 
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and treatments by segment. The construction engineer can also help with techniques, 

experience, and equipment, and assure that any special contract requirements are upheld and 

implemented correctly. Remember that the Implementation Phase for revegetation begins 

prior to road construction and continues after construction is complete, so if there are two 

separate engineers, activities must be coordinated with both.

Before construction begins, a meeting should be scheduled with the construction engineer 

to discuss the Revegetation Plan. This meeting will cover the objectives for revegetation and 

the tasks that need to be coordinated with road construction activities. The revegetation 

plan should be taken to the project site and issues that might be associated with the various 

revegetation tasks should be discussed. The construction engineer needs to be aware of all 

details of the revegetation treatments and how they are to be implemented. Plan on-site project 

reviews early to discuss plans and allow ample time to overcome diffi culties in integrating 

construction and revegetation design. Identify and assess potential areas of confl ict between 

road construction activities and revegetation objectives. Review these potential confl icts oneby-one, and discuss ways to resolve them. Special contract requirements (discussed in Chapter 

2) should also be reviewed. These may cover topics such as topsoil salvage, slope treatments, 

or other key practices. The construction engineers will also have ideas that can help translate 

revegetation plans to construction contractors.

Of course, it is best to minimize site disturbances in the fi rst place. During the Planning 

Phase, collaboration with the design engineer is essential in potentially reducing the size 

of the construction footprint of the project. The construction engineer can often identify 

opportunities for reducing potential problems, in some cases, making changes that can modify 

or even eliminate certain construction or revegetation treatments.

During these meetings, it is critical to respect and learn from the experience and insights of 

the construction engineer. They may have worked with revegetation treatments on other road 

projects and could have ideas on installation methods on the current project. There are many 

ways to achieve revegetation objectives; collaboration between the construction engineer and 

the revegetation specialist will always create the best results. With your combined expertise, 

new and innovative approaches can also be created.

After the development of treatment details and timelines, another meeting should be scheduled 

to get the construction engineer’s input and to double-check quantities, areas, supplies, and 

equipment for revegetation treatments. As road construction proceeds, periodic meetings 

should be scheduled to discuss confl icts and refi ne revegetation plans.

Before road construction begins, roles and responsibilities on the job site need to be clearly 

defi ned. Refer to procedural manuals for the agencies involved and make sure you follow their 

chain of authority. The revegetation specialist must coordinate directly with the construction 

engineer. The construction engineer will be directing all phases of road construction, and you 

must always ask permission to communicate directly with any of the contractors. Remember, 

your role as a revegetation specialist is not to direct the construction contractors, but to play an 

advisory role so that all contract requirements can be carried out eff ectively and on schedule.

The more that you are on site during all phases of construction, the stronger your relationships 

with the construction engineer and construction contractors will be. These strong working 

relationships will ensure that all revegetation plans will be implemented successfully. 

Sometimes, spur-of-the-moment meetings must be called to address immediate problems or 

to adapt to shifting tactics. You must understand that all road projects will not go exactly as 

planned, so be as responsive as possible.

9.3 REVIEW TREATMENT DETAILS AND TIMELINES

The Revegetation Plan will outline all of the treatment details, quantities, and schedules for the 

project. However, details often need to be revised or defi ned more specifi cally. Accurate and 

reasonable calculations and schedules will help the revegetation specialist collaborate more 

eff ectively with contractors and agency suppliers. At this stage of the process, you should refi ne 

calculations and timelines in suffi cient detail to begin the contracting process. Calculating and 

rechecking areas to be treated, needed equipment and supplies, and schedules and budgets 

will ensure that contracted items are accurately identifi ed and defi ned.
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Wild seed collection

Noxious weed treatment

Tasks

Year

Seed increase

Seed storage

Seedling procurement

Topsoiling

Fertilizer procurement

Mycorrhizae procurement

Hydroseeding

Planting

Seedling mulching

Browsing control

-3 -2 -1 0 1 2 3

Implementation

Road Construction

Figure 9.1 – Example implementation timeline. Implementing the revegetation plan often 

requires separate schedules and diff erent contractors, so coordination is essential.

173

In general, four types of implementation activities take place in revegetation, and the 

Implementation Guides following this chapter give specifi c details and follow the same 

general organization:

1) Implementing Site and Soil Treatments: fertilizers, tillage, mulches, topsoil, organic 

matter amendments, lime amendments, benefi cial soil microorganisms, and 

topographic enhancements.

2) Obtaining Plants: collecting wild seeds, collecting wild cuttings, collecting wild plants, 

nursery seed production, nursery cutting production, and nursery plant production.

3) Installing Plants: seeding, hydroseeding, installing cuttings, installing plants.

4) Caring for Plants: post installation care.

Advanced planning is essential. Many implementation tasks begin up to three years before 

road construction. Proper planning will ensure that all materials will be ready at the appropriate 

time during the construction phase. (Planting can occur as early as year one in a multi-year 

construction project.) Be aware that procuring plant materials and implementing mitigating 

treatments will involve separate schedules with diff erent contractors. Therefore, developing an 

implementation timeline is essential in order to keep all scheduling details straight. An example 

of an implementation timeline is shown in Figure 9.1.

Most timelines have interdependent and time-linked tasks. In Figure 9.1, for instance, the 

hydroseeding contract is dependent on the success of the seed increase contract. Before that, 

the seed increase contract depends on the wildland seeds collected by agency personnel or 

contractors. The success of the hydroseeding contract rests on the successful execution of two 

tasks that must begin years before hydroseeding implementation. Detailed schedules and 

timelines are necessary to coordinate these activities. The Implementation Guides provide 

more detailed information on how to organize and schedule the various tasks.

When creating timelines for tasks, be sure to incorporate the advance time needed to issue 

contracts. This is especially crucial when ordering plant materials, which will require several years 

before needed species and quantities can be grown. However, even for routine procurement 

of equipment or supplies, nine to twelve months of advance notice will result in better prices, 

since suppliers will have more time to plan their orders. Reputable contractors have plenty of 
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20 + 1000 3 20 60

20 + 1020 4 20 80

20 + 1040 6 20 120

20 + 1060 7 20 140

20 + 1080 6 20 120

20 + 1100 4 20 80

20 + 1120 2 20 40

640

Area (m2)

Distance

between

stations (m)

Slope

Station Length (m)

Total (m2):

Acres: 0.16

Figure 9.2 – How to calculate 

areas being treated.

174

work and may not be available on short notice. Implementation Guides provide more detail on 

scheduling and contracting timelines for individual tasks.

Renting equipment and calculating quantities of materials is an essential part of implementation. 

In many cases, the construction engineer can provide you with information regarding cubic 

volumes, surface areas, and haul distances as they refer to plans and specifi cations. Accurate 

calculations are essential to develop contracts for various tasks. Figure 9.2 shows example 

calculations to determine areas being treated. Further details on developing quantity 

specifi cations for the various tasks of implementation can be found in the Implementation 

Guides following this chapter.

Once treatment details and timelines have been developed, meet with the construction engineer 

and review quantities, timing, materials, and equipment, as well as overall strategies. If areas 

are only estimates at this stage due to possible changes while the road is constructed, express 

them as ranges (e.g., 40 to 50 acres) when issuing contracts. After the site has been prepared, 

you can narrow these ranges down to exact numbers. Be sure to allow for contingencies, 

especially when ordering seeds. Once you feel confi dent about the details and timing, develop 

contracts to carry out the work.

9.4 DEVELOP CONTRACTS

A contract functions as a detailed plan for each task or set of tasks, communicating the desired 

outcome for the work. Contracts are essential tools for implementing revegetation treatments. 

Even if the work is to be carried out by personnel within the agency, approaching the tasks as if 

they were private contracts will facilitate clear communications and a high-quality job. (Check 

agency procedural manuals for how to create in-house agreements.) The Revegetation Plan 

and the treatment details (developed above) are used to create a contract. The contract details 

the implementation work to be done by the contractor or agency personnel for that task, with 

clear defi nitions of roles and schedules.

Depending on the complexity of the project, multiple contractors are usually involved. 

As emphasized previously, developing contracts well in advance of the work is necessary in 

order to ensure proper scheduling. Contracts vary by the type of work to be done and by the 

types of parties involved. In general a contract should defi ne:

 · Supplies/services to be provided;

 · Scope of work (size, schedule, and so on);
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 · Project location;

 · Contractor obligations;

 · Revegetation specialist obligations;

 · Delivery details (who, how, when, including timelines and deadlines); 

 · Quality standards;

 · Contractor quality assurance plan (to be provided by contractor);

 · Revegetation specialist quality assurance plan (to be provided by revegetation specialist 

who will be inspecting the contractor’s work);

 · Price;

 · Payment method (submission of invoices, approval of work);

 · Contractor’s designated representative (so you only coordinate with one person);

 · Safety plan; and

 · Other terms and conditions (e.g., what to do in the event of changes).

Usually you will put out a call for proposals for a task with most of the above details included. 

Contractors will provide their off ers for completing the work, including their plans for safety 

and quality control. For technical work, the contractor usually provides an explanation of the 

proposed technical approach for each task to be performed. The most suitable contractor 

is selected for the task and then the details are worked out in writing. Make sure that the 

contractor designates one representative to be your contact person for the project; having 

just one “point of contact” reduces confusion and makes communication easier. Also, when 

detailing “other terms and conditions,” especially for plant materials, make sure there are 

clauses that cover possible variations in quantity or quality. For example, low quality seeds 

may still be usable, but perhaps a fair price reduction can be agreed upon if the germination is 

below the contract specifi cations.

Quality control is essential for every implementation task. Quality control plans assure that the 

contracted tasks were performed as planned. Usually the contractor provides a quality control 

plan describing how their organization will monitor their work and assure that the contract 

is effi ciently fulfi lled. The revegetation specialist must also defi ne, in advance, the standards 

by which work will be assessed and detail how work will be inspected. Predefi ned quality 

standards are essential to assure that everyone is working towards the same clearly defi ned 

goal to achieve the DFCs for the project. More information on quality control is provided in the 

next section. An example contract (between the USDA Forest Service and a private contractor) 

is provided on the following pages.

9.5 INSTALL TREATMENTS

The Revegetation Plan, in part, is based on the construction plans and predicted postconstruction outcomes. However, after road construction is complete, you will often fi nd that 

the predictions do not exactly match the reality. In addition, materials available may change. 

To adapt to these unplanned changes, implementation tasks are updated during and after 

construction based on actual changes to the site or actual materials available at the time of 

implementation. A concise revegetation plan, combined with clear contract performance work 

statements and consistent communication, will provide an adaptive framework from which 

change can readily occur.

Prior to installation of treatments, several questions should be asked and evaluated. First, 

determine if there are any major unplanned construction changes that require new road plans 

and cross-sections. If so, these changes need to be documented on the revegetation map and 

a plan needs to be developed to revegetate them. Second, reassess the limiting factors to 

revegetation success as described in Chapter 5. For example, is the rooting depth as predicted? 

Is there fracturing in the bedrock? Are some slopes steeper than originally designed? Was 

ground water intercepted? Is there enough topsoil salvaged to reapply at the planned rates? 

Are there areas of instability? Did unexpected weeds show up? If any of the answers are diff erent 

than planned, mitigation treatments should be reevaluated. Third, reevaluate the revegetation 

unit map. Are the units located on the map correctly? Are the descriptions still valid? If they are 

not, then make the changes so each management unit can be developed properly. Adaptive 
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Example Contract

Contract 

No.

 53-04R3-4-045 Project 

Name:

Weston-Elgin 

Road Construction 

Project

County: Umatilla

Contractor: Issuing and Billing Offi ce:

Umatilla National Forest

2517 SW Hailey Avenue

Pendleton, OR 97801

Item

No.

Subitem

No.

Description Quantity 

to Date

Quantity

Ordered

Unit Unit

 Price

Amount

1

Hydraulically apply 

permanent seeding* 

to newly fi nished 

cut and fi ll slopes.

1a. Fall 2005 40 Acre $3,000 $120,000

1b. Fall 2006 5 Acre $3,300 $16,500

2 Hand plant shrubs*, 

and conifers*, over 2 

seasons.

2a. Fall 2005, shrubs 

only 

5,600 Plant $3.00 $16,800

2b. Fall 2006**, conifers 

and shrubs. 2,700 

conifers. 2,400 

shrubs.

5,100 Plant $3.00 $15,300

3 Pneumatically install 

compost/ mulch 

erosion blanket w/

seed* onto two (2) 

fi ll slopes.

2 acres Acre $12,000 $24,000

Required Delivery Date: All work shall be completed by November 15, 

2005. Work is estimated to begin October 15, 2005. All work shall be 

completed within 10 calendar days. Timing of current construction 

and access to work sites may necessitate work on weekends and short 

notifi cations to begin work.

All items will be awarded to one (1) contractor.

* Government supplied materials

** Contractor to perform subitems 1b and 2b together during 

Oct.-Nov. of 2006.

Total Price: 

$192,600

Contractor: (Name and Signature)

Requested By: (Name and Signature)

Jim Scott, COTR 

Fund Authorization: (Name and Signature)

Ordered By: (Name and Signature)

Contracting Offi cer

Order Date: Job Code: WGFCNA
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EXAMPLE STATEMENT OF WORK

Weston-Elgin Road Construction Project, HWY 204

M.P. 10.65 to M.P. 20.77

Walla Walla Ranger District, Umatilla National Forest

Umatilla County, Oregon

Elevation 3,800 to 5,000 ft

Location of work:

The project area is located in Umatilla County, near Tollgate, OR and east of 

Athena, OR on Highway 204. Project is located between MP 10.65 and MP 20.77.

Athena is located midway between Pendleton, OR and Walla Walla, WA along 

Highway 11. See attached map.

Construction of the road will span two seasons and require seeding and planting 

work to be performed in both the fall of 2005 and 2006, with the majority of work 

completed in 2005.

Description of Work and Standards:

Item 1. Hydraulically apply seeds, mulch, fertilizer, and tackifi er to fi nished cut and fi ll 

slopes associated with new road construction. Provide permanent seeding for 

up to 45 acres of cut, fi ll, and adjacent obliterated road surfaces. Government will 

furnish all seeds. The majority of slopes will average 1V:2H with a small amount of 

1V:1.5H. Areas are adjacent to existing paved road and/or graveled surfaces. The 

majority of work (95%) can be performed from the tower; however, a hose lay 

(up to 100 ft) will be required for a single large fi ll. The permanent seeding work 

window for this project will be between October 1 and November 15, 2005–6, 

unless alternative dates are mutually agreed upon.

Hydraulically combine and apply EcoFibre® (http://www.canforpfd.com) @ 

2,000 lb/acre, Biosol® (http://www.pawneebuttesseed.com) at 1,200 lb/acre and 

Super Tack® at manufacturer’s recommended rate; add XL crosslinker at 40% the 

weight of Super Tack® (http://www.ranteccorp.com) for slopes 1V:2H or steeper 

(approximately 5 ac).

Equivalent products may be substituted at the discretion of the government.

Item 2. Hand-plant 1+0 container and bareroot hardwood nursery stock in fall 2005. 

Hand-plant 1+0 hardwood container nursery stock and 2+0 conifer container 

stock in fall 2006. Use hand tools to plant styro-15 plugs, styro-40 plugs, and 

bareroot plant materials. Plant spacing distances will be assigned by the COTR 

for each site. Plant up to 10,700 individuals (in total, 2 years) in cut and fi ll slopes, 

obliterated road surfaces, and a short segment of riparian zones. Areas are 

adjacent to existing paved road and/or graveled surfaces. Planting work window 

for this project will be between October 1 and November 15, 2005–6, unless 

alternative dates are mutually agreed upon.

Contractor will be responsible for loading, transporting, and care of all living plant 

material once in possession in both 2005 and 2006. Contractor is responsible for 

all scheduling and delivery of plant materials from a private nursery in MiltonFreewater, OR. The facility is located on HWY 11 and is approximately 40 to 45 

minutes from the project. Upon award, location and contact information will 

be provided.
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Planned Weston-Elgin Revegetation Project Plant Materials for Fall Planting of 2005 and 2006

Species Stocktype and Quantity Total by Species

Bareroot Styro-15 Styro-40

Alnus viridis s. sinuata 0 30 0 30 

Amelanchier alnifolia 0 0 720 720 

Cornus sericea s. sericea 0 175 0 175 

Holodiscus discolor 0 0 1,160 1,160 

Physocarpus malvaceus 476 250 1,330 2,056

Populus trichocarpa 0 0 80 80 

Rosa woodsii 0 0 263 263 

Rubus parvifl orus 0 0 204 204 

Sambucus nigra s. cerulea 0 192 0 192 

Sorbus scopulina 0 0 620 620 

Spiraea splendens 0 0 100 100 

Total 2005 476 647 4,477 5,600

 

1+0 Symphoricarpos albus 0 0 1,500 1,500 

2+0 Conifers 0 2,700 2,700 

1+0 Additional shrubs 900 900

Total 2006 5,100

Item 3. Pneumatically install compost/mulch erosion blanket w/tackifi er and seeds. Apply 

an even coverage 2 inches in depth over 2 acres of slopes ranging from 1V:2H to 

1V:1.5H. Access will be from existing roads. Contractor must provide compost 

specifi cations to the COTR prior to start work date. Compost must conform to U.S. 

composting council standards and be state certifi ed in Oregon and Washington. See 

evaluating compost quality (http://www.compostingcouncil.org) for standards of 

acceptable compost. An accessible compost storage site will be provided within 

one (1) mile of the installation site. Site is accessible to trucks and trailers.

Contractor Quality Control Plan:

The Contractor shall prepare a brief Quality Assurance Plan and submit it with 

the completed bid.

Government Quality Assurance Plan:

A qualifi ed USFS COTR will be on site during all phases of project fi eldwork, 

providing technical support and ensuring that project objectives are met. The 

contractor is fully expected to take an active role in providing, sharing, and 

advising in technical aspects that may benefi t the project outcome.

The following plan is to be used by the Government for quality assurance:

Item 1. Application. Hydroseeding slurry mixture, rate of application, uniformity, and 

coverage will be inspected. Apply hydroseeding mix so no holes exist. Apply so 

that no gaps exist between the matrix and the soil. Application is not allowed 

over frozen ground or snow or during periods of extended rainfall. A tracer 

(mulch or dye) suffi cient to visibly measure coverage and progress is mandatory 
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in each slurry unit. Follow-up monitoring to determine germination and survival 

will be carried out during May, July, and September 2006-7. Monitoring will be 

used to assess the eff ectiveness of treatment and determine whether followup treatments are needed to adequately stabilize seeded slopes. A follow-on 

contract may be issued for additional hydroseeding, if necessary, as determined 

by monitoring.

All equipment shall be free of weed seeds. Hydroseeding equipment shall be clean 

and free of all previous seeds, fertilizer, mulch, or any hydroseeding products used 

on prior jobs. Equipment will be inspected prior to initial applications. If equipment 

does not pass inspection, the contractor will be required to clean equipment off -

site at an approved facility before returning to the project site. The Government 

may not be held liable for lost time due to re-cleaning of equipment.

Item2. Shrub and tree planting. Vertical planting depth, site selection, species 

appropriateness, handling, mechanical damage during planting, that is, excessive 

broken branches, tops, and roots, excessive damage to bark which exposes 

cambium, will be inspected. Due to the perishable nature of trees and shrubs, care 

and protection is considered critical and will be carefully monitored throughout 

the planting schedule to ensure proper care. The COTR will frequently observe 

planting in progress, dig trees and/or shrubs to check underground planting 

quality, and observe planting methods. Follow-up monitoring to determine 

survival and establishment will be carried out during May, July, and September 

2006-7. Monitoring will be used to assess the eff ectiveness of plantings and 

determine whether follow-up treatments are needed to adequately stabilize 

selected slopes. A follow-on contract may be issued for additional planting, if 

necessary, as determined by monitoring.

Item 3. Pneumatically install compost/mulch erosion blanket with tackifi er, fertilizer, 

and seeds. Evenness and consistency of application to slopes will be monitored. 

Ingredients, additives, and injection will be monitored as well. Application is not 

permitted over frozen ground or snow or during periods of extended rainfall. 

Contractor must provide compost specifi cations to the COTR prior to work 

start date. Standards must conform to U.S. Composting Council standards. See 

evaluating compost quality (http://www.compostingcouncil.org) for standards 

of acceptable compost. The COTR will evaluate test results for compost furnished 

by contractor and randomly inspect and/or take samples from material stored on 

site. Government will furnish seeds.

Measurement and Payment:

Payment for hydroseeding will be on a per acre basis. Additional acreage will be 

paid at the stated contract price and performed via a follow-on contract.

Payment for installed compost erosion blanket will be on a per acre basis.

Payment for hand shrub and tree planting will be on a per plant basis.

Government Furnished Material:

The government shall provide all seeds to the project site. The government shall 

produce all conifers and shrubs; contractor is responsible for pick-up, delivery, 

and care during the contract period.

Schedule:

Treatment/Year 2005 

(Acres/Plants)

2006 

(Acres/Plants)

Total 

(Acres/Plants)

1) Hydroseeding 40 ac 5 ac 45 ac

2) Hand-plant shrubs and conifers 5,100 plants 5,600 plants 10,700 plants

3) Install compost and seeds 2 ac 2 ac
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management is ongoing throughout all phases. Change is a certainty, and preparedness 

provides options and allows the revegetation specialist to respond to these situations.

The status of available materials must be determined. The fi nal inventories should be obtained 

from the agency staff and contractors. The inventories will include the quantities of each species 

for seeds and/or seedlings, topsoil supply, and so on. Producers may not be able to deliver 

the exact quantities ordered. Seed producers may have succeeded in growing more seeds for 

certain species while producing less of other species. The nursery may have been aff ected by 

frosts, insects, disease, or other events that reduced the inventory for some species but not 

others. Just as likely, the nursery could have extra seedlings available for some species that 

could make up the shortage of others. Guided by the objectives and DFCs of the Revegetation 

Plan, the revegetation specialist must adapt to these changes and carry out the implementation 

tasks to the best of your ability using the materials and resources at hand.

9.6 KEEP GOOD RECORDS

During the Implementation Phase, keeping records often seems like a low priority. The fi eld 

work demands a high level of energy and attention, and time for keeping records may tend 

to fall by the wayside. However, records are invaluable, and recordkeeping is an essential part 

of implementation. Records are essential in the short-term for reporting and accountability, 

including communicating with contractors and agencies. In the long-term, records are needed 

to assess what was done, what worked, and what did not work as the project unfolded so that 

optimal results can be recreated and failures can be avoided on future projects. It is almost 

impossible to remember what was done on a project several weeks, months, or years after 

implementation. However, it will be necessary to know what happened. Without good records, 

there will be no way of piecing together the causes of failure or success and little ability to 

share “lessons learned” with peers. Record-keeping and daily diaries are very important from a 

contractual view as well. As part of doing business, there is always a chance of a dispute leading 

to a claim by a contractor. Good records provide the foundation the contracting offi cer will 

need to defend the contract administrator.

Keep a notebook or manila folder that contains the fi nal revegetation plan, contracts, diaries, 

spread-sheets, receipts, maps, and correspondence. Since the majority of this information may 

be electronic, keep a folder on your computer that contains all e-mails, spreadsheets, budgets, 

plans, and contracts. E-mails and phone conversations can be stored in one spreadsheet for 

all projects. The process of photo documentation of project development (as described in 

Chapter 11) is also important.

Keeping a simple daily log (or diary) is also invaluable. Take a few moments to jot down what 

happened at the project site each day until implementation is complete. Include thoughts of 

how things are going, any anticipated changes, and challenges and opportunities. An example 

daily diary form and template is provided in Figure 9.3. While the example shows a diary for 

contract work, the same template can be utilized to keep records of your own work, that of 

other agencies, and overall project development.

Records are also used to develop reports when it is necessary to document accomplishments 

to date. Reporting requirements vary, but some type of accomplishment report is usually due 

quarterly or annually. Monitoring reports (discussed more in Chapters 11 and 12) are essential 

in order for environmental agencies to ensure that you fulfi lled objectives and appropriately 

addressed environmental regulations. While putting these reports together, take a few hours 

to organize the fi les and summarize the information in them. At the completion of the entire 

project, a fi nal report is assembled based on the records that were kept throughout the project. 

For this reason, good record-keeping is essential.

9.7 CARRY OUT QUALITY ASSURANCE

To evaluate the eff ectiveness of implementation work, quality assurance standards are set 

and quality is monitored until each task is complete. The standards for quality assurance are 

linked to the DFCs that were set in the Planning Phase. In other words, many of the quality 

assurance standards translate aspects of the DFCs (e.g., desired percent vegetative cover) 

into short-term standards for implementation work (e.g., quantity of seeds applied). Details 

for quality assurance standards are defi ned in the contract specifi cations. The contractor will 

provide monitoring and inspection of their own work to assure that tasks are carried out as 
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Contract Daily Diary 1. PROJECT SITE

2. CONTRACT NO.

3. PROJECT

4. CONTRACTOR 5. CONTRACTOR REPRESENTATIVE ON SITE

6. OFFICIALS ON SITE

7. DATE 8. DAY OF WEEK 9. TIME ARRIVED 10. TIME DEPARTED 11. WEATHER

12. TEMPERATURE  ̊F

Min. Max.

13. GROUND CONDITION 14. CONTRACT TIME 15. DAYS USED 16. COMPLETION DATE

17. TIME USED (%) 18. WORK COMPLETED (%) 19. WORK ON SCHEDULE 20. CONTRACTOR'S WORK - (X Appropriate Box)

21. CHANGE ORDERS/AMENDMENTS ISSUED 22. WORK ORDERS ISSUED (Include SUSPEND/RESUME)

23. MATERIALS FURNISHED TO JOB SITE (Furnished by G-Govt., C-Cont; S-Subcont.) 24. LIST EQUIPMENT ON SITE (Furnished by G-Govt., C-Cont; S-Subcont.)

25. List Contract Payments, Reports, Correspondence, ETC. 26. Workers On Site Number

Item Prep Submit Classification PRIME

Type Contract Item Number and Location of Use Hours Used

YES

YES NO - Explain in Narrative

NO Acceptable Unacceptable Explain In Narrative

SUB

27. Government Provided Services Adequately and Timely

28. NARRATIVE REPORT

29. SIGNATURE

Distribution: Original - CO (weekly); copies: COR, SO, PROJ ENG

Previous editions of this form are obsolete

30. TITLE

FS-6300-20 (5/96)

31. ADDTL SPACE NEEDED

 (Continued on 6300-21)

(Reference FSH 6309.11) 

Upper Grange Road

Davis Lee 06/07/06 Reveg Specialist

54-46-37

Upper Grange Road Revegetation (working on Reveg Units 1-3 today)

Plant and Protect Inc.

Me (Davis Lee)

6/7/06 Wed. 07:30 16:00

X X

Overcast, Thunderclouds west

Moist, firm — good condition

No changes yet, may reschedule tomorrow if

heavy rain continues tonight.

Seed mix RRCA5. 50 lbs for use w/mulch (G)

Mack truck w/ lowboy (C)

Cat 9506 loader (C)

Kenworth truck with Finn blower 

Jane's SUV (C)

Hydroseeder (C)

Trailer w/ mulch loads

Harry Medford (truck)

Julio Valdovinos (hydro)

Lila Carev (mulch)

1

1

1

537 yards of certified compost (for mulch) (C)

Install hydromulch (blow on compost & 

seed mix)

Jane McLean

45 55 6/7/06 to 6/14/06 1

14% 20%

Jane McLean 1

Met with Jane and crew (Harry, Julio, Lila) from 07:30 - 08:15. Looked over project site and reviewed 

compost/seed installation strategy. Talked safety: traffic, orange vests, PPE, working around equipment, 

evacuation plan in case of injury, equipment, footing OK! I inspected compost, appears high quality (collected 

6 samples to be combined for test later). 08:30 crew began to unload and stage equipment, loading compost 

into blower (25 yds) mounted on Mack truck. Jane and Davis inspect reveg units/areas and explored secondary source of water (east end) if needed, permit OK. 09:30 crew began blowing compost/seed mix onto Reveg 

Units 1 & 3. Good job with careful hose placement. 14:00, rain began, a sprinkle then a downpour. 16:00, 

stopped work for day, compost becoming heavy with too much water so not blowing as far. If dries out 

overnight, will resume application tomorrow. Otherwise will have to postpone until dry enough to blow. 

Looks like rate can be 7-8 loads/day possible in good conditions. No other issues.

Figure 9.3 – Example of contract daily diary (source: USDA Forest Service).

181

contracted. The revegetation specialist is responsible for assessing the quality of each task to 

assure all tasks were satisfactorily completed and all contract requirements have been met so 

the contractor can be released from further obligations and fully paid.

On revegetation contracts, project objectives or standards are typically referred to as contract 

specifi cations. For example, a hydroseeding contract has a specifi cation to apply 30 lb of seeds, 

1,000 lb of wood fi ber mulch, and 50 lb of tackifi er per ac to 20 ac of cut and fi ll slope. Quality 

control for this task might be to count the pounds of seeds, wood fi ber, and tackifi er going 

into the hydroseeder tank and measure the area to which the mix is applied. This assessment 

can assure that the rate of materials applied on a per-acre basis is appropriate. If the calculated 

amount of material per acre does not match the stated objective or contract specifi cations, the 

amount is adjusted to meet the specifi cations. Quality assessment not only assures that the 

contractor meets his or her obligations, but alerts them when specifi cations are not being met 
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so that corrections can be made. For any task, quality assurance standards describe what form 

of measurements will be used to assess the work.

9.8 IMPLEMENT EARLY MAINTENANCE AND MONITORING

Just after implementation, short-term monitoring of the project begins. Short-term monitoring 

is necessary to confi rm that eff orts to establish vegetation on the site were eff ective, and to 

correct shortcomings to ensure project objectives are achieved. Quality assurance confi rmed 

that the predetermined amounts of fertilizer, tackifi er, hydromulch, and seeds were put into the 

hydroseeding tank as specifi ed, and that the materials were placed in the correct areas at the 

correct density. Short-term monitoring then determines whether the revegetation objectives 

of the plan were met using these rates and materials. For example, were germination rates 

suffi cient? Are the plants surviving and becoming established? Short-term monitoring assesses 

project development as it relates to the DFCs. If objectives are not being met, determining the 

reason(s) should become a priority before further revegetation work is proposed. Short-term 

monitoring and management of roadside revegetation projects is discussed in Chapters 11 and 

12. The information from short-term monitoring determines the level of maintenance that will 

be carried out to keep the project developing as planned.

Timelines for roadside revegetation projects can span several seasons or even several years, 

which means that early maintenance of some road segments will be taking place at the same 

time that other segments are being implemented. Sometimes, maintenance work is built into 

the contract as part of implementation. Once contract work is completed and the contractor 

has been released (fi nal satisfactory inspection), maintenance begins. Most maintenance 

tasks will have been planned in advance, such as applying fertilizers after three months, or 

passing through to control weeds. Early maintenance also includes identifying and correcting 

unforeseen problems quickly. Unforeseen events include weather problems (e.g., drought), an 

unexpected invasion of weeds, impacts of pests, vandalism, or other issues that might mean 

that the project will not develop as planned unless corrections are made. If corrective measures 

are needed, additional contracts may be issued to carry out the tasks. Road maintenance 

must also be coordinated with the revegetation plan. This could ensure that herbicide is not 

applied to the newly planted areas. Discussion of monitoring and management continues in 

Chapter 11.

9.9 CONCLUSION

The Implementation Phase calls for fl exibility, adaptability, and opportunism. At times, 

the implementation work demands a willingness to travel to the construction site on short 

notice to assess issues as they arise. The process requires the vision to fulfi ll the overall project 

objectives while working with, and adapting to, the resources and conditions at hand. Keeping 

channels of communication open with the construction engineer and with the revegetation 

contractors is an essential aspect of eff ective implementation. Advanced scheduling and careful 

calculations of timing, supplies, and services needed are necessary. Issuing clear contracts for 

implementation work, regular evaluations and quality assurance as treatments are carried out, 

and good recordkeeping are necessary to ensure the revegetation is implemented eff ectively. 

Short-term maintenance and monitoring help to identify and correct any shortcomings quickly 

in order to fulfi ll project objectives. The Implementation Guides following this chapter provide 

further details about individual implementation tasks, including working with soil and site 

treatments, obtaining plant materials, installing and caring for plants.
10 IMPLEMENTATION GUIDES

Chapter 10 details the practices common to most revegetation projects. It is divided into 19 

subchapters, called implementation guides, which summarize the important information 

needed to execute each practice.

Implementation guides are grouped into four subject areas: 

 · 10.1 Soil and Site Treatments,

 · 10.2 Obtaining Plant Materials,

 · 10.3 Installing Plant Materials, and

 · 10.4 Post Installation Care of Plant Materials.

The eight guides in Section 10.1, Soil and Site Treatments, explain how to improve site and 

soil conditions prior to the installation of plant materials. These guides cover the mitigating 

measures most often referenced in Chapter 5.

Section 10.2, Obtaining Plant Materials, covers six implementation guides that pertain to 

collecting and propagating plant materials. These guides describe how to take the species 

lists developed in Chapter 6 and obtain the desired species in the wild as seed, cuttings, or 

seedlings. These guides also cover how to increase gathered wild collections at nurseries to 

ensure that the revegetation project has suffi cient quantities of plant materials.

Once plant materials are obtained from the wild or from nurseries, they are installed on the 

project site. The four guides in Section 10.3, Installing Plant Materials, cover the techniques for 

sowing seed, installing cuttings, and planting seedlings. They also cover how to determine the 

quality of the plant materials and how to care for them during storage and transportation.

Section 10.4, Post Installation Care of Plant Materials, outlines those practices that take place 

after the installation of plant materials. These practices help ensure that plants will become 

established. Practices include protecting seedlings from animal browsing, installing shade 

cards, irrigating, and installing tree shelters.

10.1 SOIL AND SITE TREATMENTS

Most post-construction sites are in poor condition for plant growth and will require the 

implementation of mitigating measures if full or even partial revegetation is expected. The 

following set of implementation guides cover the common mitigating measures for improving 

site conditions after construction. The implementation guide to fertilizers, Section 10.1.1, 

covers how to determine the quantity, type, and application method of fertilizers. Tillage, 

Section 10.1.2, describes the common practices of tilling the soil to improve water infi ltration 

and root growing environment. Improving seed germination and reducing surface erosion 

can be accomplished through the application of mulches, which is detailed in Section 

10.1.3, Mulches.

Section 10.1.4, Topsoil, outlines the removal, storage, and application of topsoil to reconstruct 

soil on highly disturbed sites. For sites where topsoil is not available or in short supply, organic 

matter can be applied to improve post-construction soils. Section 10.1.5, Organic Matter 

Amendments, discusses the types of organic matter available, how to determine rates, and 

how it is applied. On some sites where the topsoil has been removed, pH levels will need to 

be raised to improve plant growth. Section 10.1.6, Lime Amendments, details the methods for 

determining liming rates, materials, and application methods. Many sites devoid of topsoil will 

require the introduction of mycorrhizae or nitrogen fi xing plants. Section 10.1.7, Benefi cial Soil 

Microorganisms, covers how to obtain and apply the appropriate sources of these important 

biological organisms. Revegetation projects can be enhanced by integrating plants into 

bioengineering structures, water capture features, or planting islands or pockets. These are 

discussed in Section 10.1.8, Topographic Enhancements.

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10.1.1 FERTILIZERS 

10.1.1.1 Introduction

Fertilizers are used to bring soil nutrients up to levels essential for establishing and maintaining 

a desired plant community. When applied within a soil fertility strategy, using fertilizer can be 

a great tool for revegetation. In recent years, however, the use of fertilizers on roadsides has 

come under greater public scrutiny and more restrictive water quality laws. Many roads are 

adjacent to streams, lakes, or residential areas which can be aff ected by runoff or leaching of 

inappropriately applied fertilizers. It is important for the revegetation specialist to learn how to 

develop fertilizer prescriptions that integrate short- and long-term site fertility goals with water 

quality objectives. 

Use of commercial fertilizer is only one of many options to increase nutrient levels. A soil fertility 

strategy should also consider the application of topsoil, mulch, compost, wood waste, biosolids, 

and/or the planting of nitrogen-fi xing species. This section will guide the revegetation specialist 

through the steps necessary to develop a site specifi c fertilizer prescription. The process for 

developing a fertilizer prescription follows these steps:

 · Determine nutrient thresholds and defi cits,

 · Delineate areas to be fertilized,

 · Select fertilizer analysis,

 · Select fertilizer release rates,

 · Determine application rates,

 · Determine timing and frequency, and

 · Select application method.

The fertilizer prescription is the basic instructions for ordering and applying fertilizers. 

10.1.1.2 Develop Nutrient Thresholds and Determine Defi cits

All sites have a minimum, or threshold, level of nutrients that must be met for each plant 

community to become functioning and self-sustaining (See Section 5.5). Threshold values can 

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Figure 10.1 – Threshold values are determined from reference sites. In this example, the 

threshold was established at 1,100 lb/ac, which was between the total N of a disturbed 

reference site with “poor” revegetation (A) and one with “fair” revegetation (B). Total N in postconstruction soils was 650 lb/ac (C), making these soils defi cient by 450 lb/ac. The undisturbed 

topsoil of reference sites showed a total N of 2,430 lb/ac (D), which sets the target levels of 

nitrogen between 1,100 and 2,430 lb/ac.

D

3,000

2,500

2,000

1,500

1,000

500

0

Undisturbed

RS - Topsoil

Total

N (lbs/ac)

Soil Condition

Threshold

Deficit

Target Nitrogen Levels

Disturbed RS

(“fair”

revegetation)

Disturbed RS

(“poor”

revegetation)

Post

Construction

Soils

B

A C

184
be determined by comparing soil tests from several disturbed and undisturbed reference sites 

(See Chapter 4). Disturbed reference sites should range from poor success to good. Based on 

nutrient values from good and poor revegetation sites, a target can be estimated between 

these values. Figure 10.1 gives an example of how a nitrogen threshold value was obtained 

by evaluating the total soil nitrogen levels from two disturbed reference sites, one considered 

“fair” revegetation and one considered “poor.” The threshold was set between these two 

nitrogen levels. Threshold levels represent the minimum level of nutrients needed for a site. 

However, higher nutrient levels are more desirable. In fact, the target nitrogen levels in this 

example for establishing and maintaining the original plant community would be closer to the 

undisturbed reference site.

To determine whether any nutrient is defi cient, post-construction soils must be collected and 

tested. The values obtained from these tests are compared against target values to determine 

if a defi ciency exists. By comparing post-construction nutrient values against threshold values, 

the nutrient defi cit can be estimated for each nutrient. Figure 10.2 shows an example of how 

nitrogen defi cits are calculated based on post-construction soil tests and established threshold 

levels. In this example, total soil nitrogen is determined from soil tests. Since soil testing facilities 

report nutrients in a variety of rates, it is important to convert the rates to percentages. This is 

done by dividing values that come as gr/l, ppm, mg/kg, and ug/g by 10,000 to convert to a 

percentage. Converting percentage of nutrient in the lab sample to lb/ac of the nutrient requires 

multiplying % of nutrient, soil layer thickness, soil bulk density, and fi ne soil fraction together 

with a constant (line D). This is the pounds of nutrient in an acre of soil on the post-construction 

site. To determine the nutrient defi cit, the pounds of nutrients per acre is subtracted from the 

threshold level. This value becomes the basis for determining fertilizer prescriptions.

The availability of many nutrients is regulated by soil pH. As discussed in Section 5.5.5, many 

nutrients are tied up in low pH and high pH soils. Calcium and magnesium are less available at 

low pH; phosphorus, iron, manganese, boron, zinc and copper become unavailable in high pH 

soils. It is important to compare the pH of post-construction soils with reference site soils to 

determine if the pH is substantially diff erent between the two. If the pH of post-construction 

soils is diff erent, then taking measures to bring the pH closer to pre-disturbance values should 

be considered when developing a nutrient strategy (See Sections 5.5.5.3, 5.5.5.4, 10.1.5, 

and 10.1.6). 

10.1.1.3 Delineate Areas to be Fertilized

The post-construction project site should be delineated by distinct areas where fertilizer 

prescriptions diff er. These diff erences are usually based on post-construction soil type changes, 

topsoil salvage, organic amendment additions, or the species and plant material being grown. 

Areas adjacent to, or that feed into, live water are often delineated and treated with lower 

rates of fertilizer. Note: If seedlings of shrubs and trees are being planted, spot fertilization 

should be considered in addition to, or in lieu of, fertilizing the entire area (See Inset 10.1, 

Spot-Fertilizing Seedlings).

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Figure 10.2 – Determining the amount of nitrogen (N) needed to bring soils up to a nitrogen 

threshold can be calculated from equations shown in this spreadsheet. 

A Total soil nitrogen (N) 0.025 % From soil test of post construction soils – gr/l, 

ppm, mg/kg, ug/g divide by 10,000 for %

B Thickness of soil layer 0.5 feet The thickness of soil represented in (A)

C Soil bulk density 1.4 gr/cc

Unless known, use 1.5 for compacted subsoils, 

1.3 for undisturbed soils, 0.9 for light soils such 

as pumice

D Fine soil fraction 70 %

100% minus the rock fragment content – from 

estimates made from sieved soil prior to 

sending to lab

E N in soil layer: A * B * C * D 

* 270 = 331 lbs/ac Calculated amount of total nitrogen in soil layer To convert to kg/ha: E * 1.12

F Minimum or threshold N 

levels 1,100 lbs/ac Determined from reference sites (see Figure 10.1)

G N defi cit: F - E = 769 lbs/ac Minimum amount of N to apply to bring up 

to threshold

185
10.1.1.4 Select Fertilizer Analysis 

There are a variety of commercially available fertilizers that can be used for fertilizing disturbed 

sites associated with road construction. The composition, or makeup, of the fertilizer is called 

the fertilizer analysis. Each container of fertilizer will have a label with a stated “guaranteed 

analysis” that indicates the percentage of each nutrient contained in the fertilizer (Figure 10.3). 

The label is your guide for determining which fertilizers to select and how much to apply. Tables 

10.1 and 10.2 give analysis values for many common fertilizers. Labels can also be obtained 

from the manufacturer or fertilizer representatives.

The fertilizer label reports the nutrients as a percentage. The example label for a 50 lb bag of 

fertilizer in Figure 10.3 shows 21% nitrogen (N), which indicates that 10.5 lb of material in the 

bag is made up of nitrogen (50 * 21/100=10.5). The bag also contains 0.02 % boron (B), which 

indicates that there is 0.01 lb boron in the bag. Calculating the amount of phosphorous and 

potassium in the bag is a little trickier because the convention for reporting these nutrients is 

P2O5 and K2O instead of elemental P and K. To convert P2O5 to P, the analysis for P is divided by 

2.29. The percentage of P in the bag in Figure 10.3 is actually 2.2%, not 5% (5.0%/2.29=2.2). K2O 

is divided by 1.21 to obtain 1.6% K. 

Fertilizers are selected based on whether they contain the nutrients that are defi cient on the 

project site. For example, if nitrogen, phosphorus, and boron are defi cient, only fertilizers 

that contain these nutrients need be considered. Most fertilizers contain more than one 

nutrient. For instance, ammonium sulfate contains nitrogen and sulfur; triple superphosphate 

contains phosphorus, sulfur and calcium. Organic fertilizers often contain a range of macro 

and micronutrients. Fertilizers containing more than one nutrient should be considered if 

the nutrients contained in these fertilizers are defi cient in post-construction soils. Table 10.1 

and Table 10.2 show the combination of nutrients that are available in some commercially 

available fertilizers.

Fertilizer selection should focus fi rst on the macronutrients (nitrogen, potassium, and 

phosphorus) that are defi cient. These three nutrients are considered most important for longterm site recovery. If they are not defi cient, chances are that the remaining nutrients are not 

either. On most highly disturbed sites, nitrogen is most likely to be defi cient. This nutrient 

should be considered fi rst when approaching fertilizer selection. Table 10.2 lists common 

nitrogen fertilizers with typical label analysis. Nutrients other than nitrogen can be supplied 

by fertilizers shown in Table 10.1. It is common to apply more than one fertilizer to meet the 

various nutrient requirements of the soil.

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Total nitrogen (N) 21.00 %

 Ammonium nitrogen (6.50 %)

 Nitrate nitrogen (12.40 %)

 Urea nitrogen (2.10 %)

Available phosphate (P2

05) 5.00 %

Soluble potash (K2

O) 20.00 %

Boron (B) 0.02 %

Copper (Cu) 0.01 %

Iron (Fe) 0.10 %

Water soluble manganese (Mn) 0.05 %

Molybdenum (Mo) 0.01 %

Water soluble zinc (Zn) 0.07 %

21-5-20

All Purpose Fertilizer

Guaranteed Minimum Analysis

Figure 10.3 – An example of a fertilizer label 

for an “all purpose” fertilizer. The top numbers 

(in bold) represent the percentage of nitrogen, 

phosphorus, and potassium respectively (21%N, 

5% P2O5 , and 20% K2O). Multiplying these 

percentages by the pounds of bulk fertilizer 

applied per acre will give the quantity of each 

nutrient applied per acre. In this analysis, 500 

pounds of fertilizer in this analysis would deliver 

105 lbs N, 25 lbs P2O5 ,100 lb K2O, 0.1 lbs B, 0.05 

lbs Cu, and so on.

186
10.1.1.5 Select Fertilizer Release Rates 

Fertilizers are grouped by how quickly they break down and release nutrients to the soil. They 

are either fast-release or slow-release. Release rates are important because they will determine 

the rates at which nutrients become available to plants during the year. If nutrients are released 

during periods when vegetation cannot use them, some will be lost from the site through soil 

leaching. This is not only a waste of fertilizer, but can be source of ground water pollution.

Fast-Release Fertilizers – Fast-release fertilizers are highly soluble fertilizer salts that dissolve 

rapidly and move quickly into the soil during rainstorms or snowmelt. The fertilizer label will 

give an indication of how quickly nutrients are released. Terms such as “soluble,” “available,” 

or “water soluble” indicate that these nutrients are released relatively quickly. “Ammonium” 

and “nitrate” forms of nitrogen are also indications of fast-release fertilizers. The fertilizer label 

shown in Figure 10.3 would indicate that this bag contains a fast-release fertilizer and most of 

the nitrogen would be relatively mobile and available to plant growth within the fi rst growing 

season. Ammonium nitrate, ammonium sulfate, potassium nitrate, and urea are several 

examples of fast-release fertilizers. 

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Table 10.1 – Analysis of some common fertilizers. Nitrogen fertilizers are shown in Table 10.2.

Mono-ammonium phosphate

Source

Phosphorus Potassium Micronutrients Ca

& Mg

Available Nutrients (typical values)

% N

% P O2 5

% P% K O2

% K% S% Ca% Cu% Fe% Mn% Zn% B% Mo% Mg

Ammonium phosphate

Diammonium phosphate

Single superphosphate

Triple superphosphate

Phosphoric acid

Dicalcium phosphate

Soluble potassium phosphate

Superphosphoric acid

Potassium chloride

Potassium nitrate

Potassium sulphate

EDTA

HEEDTA

NTA

DTPA

EDDHA

Granular borax

Copper sulfate

Ferrous sulfate

Sodium molybdate

Zinc sulfate

Zinc chelate

Dolomitic limestone

Magnesium sulfate

Gypsum

Epsom salt (Epsogrow brand)

11

82

17

19

13

48 21 24

12

1

18

10 10 10 10

6

21

23

13

7

8

10

6

20

25

11.3

40

36

4

11

43

10

7 9

21 21

20

20 13

23

35

61

45

51

50

37

42

47

45

53

80

187
“Water soluble” or “available” nutrients do not always remain available or soluble after they 

are applied to the soil. Available forms of phosphorus, for instance, react in the soil to form 

less soluble compounds; potassium gets bound up in soils with moderate to high proportions 

of clay; and many of the micronutrients (e.g., zinc, copper, manganese) become unavailable 

when applied to soils with low pH (See Section 5.5.5). Unless soils are sandy or rocky, it can be 

assumed that many of the nutrients stated as “available,” except for nitrogen and sulfur, will 

become somewhat immobile once they are applied. Over time, however, these nutrients will 

become available for plant uptake. 

The advantages of fast-release fertilizers are they are relatively inexpensive, easy to handle, 

immediately available to the plant, and can be applied through a range of fertilizer spreading 

equipment. Disadvantages are that some nutrients, such as nitrogen, will leach through the soil 

profi le if they are not fi rst taken up by plants or captured by soil microorganisms in the break 

down of carbon. Nitrates from fast-release fertilizers have been found to leach through sandy 

soils to depths that are 4 times the rate of rainfall (Dancer 1975). For example, for sites with 

annual rainfalls of 12 inches, nitrate could move to a depth of four feet if it was not taken up 

by plants or soil organisms. At this depth, nitrogen would be out of range of most establishing 

root systems.

Since fast-release fertilizers are salts, they have a potential to burn foliage and roots, especially 

when fertilizers are applied at high concentrations or when applied during dry weather (See 

Section 5.5.5.2). High concentrations of fast-release fertilizers can also aff ect germination rates 

(Figure 10.4) because of the high soluble salt levels (Brooks and Blaser 1964; Carr and Ballard 

1979). Salt damage can be reduced by mixing fast-release fertilizers at lower concentrations or 

by applying them during rainy weather. 

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Table 10.2 – This table gives 

estimated nitrogen release rates 

for some commercially available 

fertilizers. Most release rates were 

obtained from lab testing. How 

they actually release on-site will 

vary from site to site, depending 

on temperature, moisture, and 

whether the fertilizer was placed 

on the surface or incorporated into 

the soil. If slow-release fertilizers 

are broadcast on the soil surface, 

release rates should be slower 

than if incorporated into the soil 

where the conditions are better 

for break down. Arid sites should 

have slower rates of release than 

sites with high moisture; cold 

sites should take longer to release 

nutrients than warm sites. First year 

nitrogen release rates for fertilizers 

are identifi ed with an asterisk were 

adapted from Claassen and Hogan 

(1998). Non-asterisk fertilizers were 

based on best guess estimates.

Source

Available Nutrients

Ammonium nitrate 34 99 to 100 0 0

10 99 to 100 34 0

21 99 to 100 0 0

82 99 to 100 0 0

7 50 to 70 2 3

15.5 99 to 100 0 0

18 99 to 100 46 0

6 50 to 70 4 1

5 95 to 99 3 1

29 95 to 99 3 10

18 95 to 99 16 12

30 99 to 100 0 0

13 99 to 100 0 45

5 50 to 70 10 5

5 50 to 70 2 4

46 99 to 100 0 0

Ammonium phosphate*

Ammonium sulfate

Anhydrous ammonia

Biosol® *

Calcium nitrate

Diammonium phosphate

Fertil-Fibers® *

Gro-Power® *

IBDU

Osmocote 18-6-12® *

Polyon PCU 40® *

Potassium nitrate

Ringer® *

Sustane® *

Urea

N %

1st year

N release

(%)

%

P2

O5

%

K2

O

188
Slow-Release Fertilizers – These fertilizers are designed to release nutrients at a much slower 

rate. To be labeled slow-release fertilizer, some states require a specifi c amount of nitrogen to 

be in a slow-release form. Forms of nitrogen shown on the label as “slowly-available” or “waterinsoluble” are good indicators that a fertilizer is in a slow-release form. The advantages of 

using slow-release fertilizers are: 1) nutrients are supplied at a time when plants are potentially 

growing; 2) less frequent applications; 3) less potential for leaching into ground water; and 

4) less potential to cause salt injury. The disadvantages are that many slow-release fertilizers 

are bulky, cost more to purchase and apply, and are limited by the type of fertilizer application 

equipment that can be used. On the whole, however, slow-release fertilizers have greater 

applicability for revegetating disturbed sites than fast-release fertilizers.

Slow-release fertilizers come in either organic or inorganic forms. Organic fertilizers include 

animal manures (including chicken, steer, cow), bone meal, fi sh emulsion, composted sewage 

sludge, and yard waste. Unprocessed organic fertilizers are hard to apply to roadside projects 

because they are bulky and high in moisture. Commercially available organic fertilizers, such as 

Fertil-FiberTM and Biosol®, have been processed to remove most moisture, which makes them 

easier to apply through most fertilizer spreading equipment. 

The agents responsible for release of nutrients from organic fertilizers are decomposing 

soil bacteria. When soil bacteria are active, the release of nutrients is high; when dormant, 

the rate is low. The release of nutrients is therefore a function of moisture and temperature, 

which governs the rate of bacterial growth. Warm temperatures and high moisture, conditions 

conducive to plant growth, are also favorable for the break down of organic fertilizers. Because 

of this, the release of nutrients from the decomposition of organic fertilizers often coincides 

with the period when plants are growing (spring and fall) and the need for nutrients is greatest. 

The nutrient release mechanism of slow-release organic fertilizers reduces the risk that highly 

mobile nutrients, such as nitrogen, will be released in the winter months when plants are 

incapable of absorbing them and the potential for leaching is greatest.

Inorganic forms of slow-release fertilizers were developed for the horticulture and landscape 

industries where they have become an eff ective method of fertilizing nursery plants. These are 

an expensive form of fertilizer and have not been tested on roadside revegetation conditions. 

Nevertheless, they should not be overlooked in their potential applicability for some native 

revegetation projects. 

Inorganic slow-release fertilizers include ureaform, nitroform, IBDU (isobutylidene diurea), 

sulfur-coated urea, and polymer-coated nitrogen, phosphorus, and potassium. These fertilizers 

have varying mechanisms for nutrient release. Fertilizer granules coated with materials that 

release nutrients only during warm, moist conditions assure that nutrients are available during 

the period that plants are most likely to be growing. These coatings include sulfur (e.g., sulfurcoated urea) and polymers. Each fertilizer has its own formulated nutrient release rate, which 

varies from 3 months to 18 months. Release rates are available from the manufacturers for most 

inorganic, slow-release fertilizers. However, it should be noted that these rates were developed 

for 70 °F soil temperatures (Rose 2002), which are higher than soil temperatures in the western 

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Figure 10.4 – Germination of 

seeds for some species can be 

reduced following exposure to a 

10-30-10 fertilizer solution at a 

rate of 750 lbs fertilizer per 1,000 

gallon hydroseeder (after Carr 

and Ballard 1979).

Without Fertilizer

Trifolium 

repens

% Germination

Festuca 

rubra

Lolium

perenne

Festuca 

arundinacea

100

90

80

70

60

50

40

30

With Fertilizer

189
United States during the spring and fall when roots and foliage are growing. If roadside soils are 

colder than 70 °F, nutrient release will take longer than what the manufacturer states. 

10.1.1.6 Determine Fertilizer Application Rates 

Fertilizer rates are determined for each defi cient nutrient as shown in Figure 10.5. The 

calculation in this example was done to eliminate a nitrogen defi cit of 769 lb/ac. Using a slowrelease fertilizer with 8% nitrogen, the amount of bulk fertilizer necessary to bring nitrogen 

levels to minimum targets is 9,613 lb/ac (769*100/8=9,613), which is an extremely high rate 

of fertilizer to apply. On the other hand, using a fast-release fertilizer with higher nitrogen 

analysis, such as ammonium nitrate (33% N), would reduce the amount of bulk fertilizer to 

2,330 lb (769*100/33 = 2,330). While there would be less weight with this more concentrated 

fertilizer, this is considered a dangerous rate of fertilizer to apply. It would be risky and wasteful 

considering the potential for leaching high amounts of nitrate through soil into the ground 

water or the possibility of creating high salt levels toxic to plant growth. This example illustrates 

the diffi culty in developing fertilizer prescriptions to meet long-term nutrient targets. How 

does the revegetation specialist develop a fertilizer strategy to meet short-term and long-term 

plant needs without over- or under-fertilizing?

The approach presented in this section is based on building long-term nutrient objectives 

around meeting short-term nutrient needs of the establishing plant community. For example, 

applying fertilizer at the time of sowing requires very low rates of available nitrogen to meet 

the fi rst year needs of the establishing vegetation. Any extra fertilizer has the potential of being 

wasted. As the vegetation develops over the next few years, the ability of the plant community 

to take up more available nutrients increases and the fertilizer rates would be gradually 

increased. This practice, however, is seldom employed in roadside revegetation projects. In 

fact, the typical fertilizer practice does just the opposite – high rates of fertilizers are put on 

with seeds before there are even plants to utilize the available nutrients. In this practice, there 

is no return to the site in later years to assess whether additional applications of fertilizers might 

be essential for vegetation maintenance or growth. The approach we advocate is applying the 

appropriate mix of fertilizers to meet the annual needs of the vegetation while building longterm nutrient capital until the plant community is self-sustaining.

Since nitrogen is the key nutrient in establishing plant communities, this approach requires 

setting short-term and long-term nitrogen requirements of the plant community being 

established. Calculating long-term nitrogen targets is covered in Section 10.1.1.2. Short-term 

targets are more diffi cult to set because they change over time. They are governed by:

 · Soil type,

 · C:N,

 · Climate,

 · Amount of vegetative cover,

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Figure 10.5 – An example of calculating fertilizer application rates to reduce nitrogen defi cits.

A Nitrogen (N) deficit 769 lbs/ac Calculated from example in Figure 10.2

B N in fertilizer 8 % From fertilizer label

C Total bulk fertilizer needed: A * 100/B = 9,613 lbs/ac To eliminate deficit

D Est. first year N release rate of fertilizer 40 % From Table 10.2 or obtain from manufacturers

E Available N first year in fertilizer from 1st

 year application: B * C * D/10,000 = 308 lbs/ac N available to plants and soil

F Short-term N target (first year) 50 lbs/ac Depends on C:N ratio, plant cover, and age (see text)

G Excess nitrogen: E - F = 258 lbs/ac Wasted N-could leach from soils into water

H Adjusted rates of fertilizer to add:

 F * 100/D * 100/B = 1,563 lbs/ac To assure that N released first year is not wasted

I Remaining N deficit: A - (H * B/100) = 644 lbs/ac Additional N needed as later applications 

 of fertilizer

190
 · Type of vegetation, and

 · Age of vegetation.

Some general guides can be helpful in setting short-term nutrient targets for available 

nitrogen. Applying fertilizer at the time of sowing, for instance, will require very low rates of 

available nitrogen the fi rst year since vegetation will not be established well enough to utilize 

it. Rates can be set below 25 lb/ac when applying fertilizer with seeds. When vegetation is 

becoming established, available N can range from 25 to 50 lb/ac (Munshower 1994: Claassen 

and Hogan 1998). After plant establishment, rates can be increased to account for increased 

plant utilization above this amount. These suggested rates should be adjusted upward on sites 

where high C:N soil amendments, such as shredded wood or straw, have been incorporated into 

the soil to compensate for nitrogen tie-up. Calculating precise rates of supplemental nitrogen 

for incorporated organic amendments is very diffi cult. In nursery settings, rates of over 100 lb 

of supplemental nitrogen have been recommended for incorporated straw, sawdust, and other 

high C:N materials (Rose and others 1995). However, applying supplemental rates in wildland 

settings should be done with caution, utilizing trials where possible to determine more precise 

fertilizer rates. Utilizing periodic soil analysis can give the revegetation specialist a better 

understanding of the soil nitrogen status. To keep testing costs low, only available nitrogen 

and total nitrogen need to be tested (See Section 5.5 for soil sampling and testing methods).

In determining how much fertilizer to apply, it is important to estimate how much nitrogen will 

be available the fi rst year and the second year. Manufacturers have this information for most 

inorganic slow release fertilizers, and Claassen and Hogan (1998) performed tests on organic 

slow release fertilizers (shown in Figure 10.2). Release rate determinations are performed in 

the laboratory. How fertilizers actually release in the fi eld will vary by the environment. In the 

example described in Figure 10.5, the fi rst year release rate of nitrogen from the slow-release 

organic fertilizer was estimated at 40%. This was a guess based on the manufacturer’s estimates 

of 55% release, but because it was being applied to a semi-arid site where decomposition of 

the fertilizer would be slow, the rate was dropped to 40% (Line D in 10.5). If 40% of the nitrogen 

became available the fi rst year, 60% would remain for the following years (Line E). At this release 

rate, 308 lb/ac of nitrogen would become available the fi rst year after application (Line F). While 

this is an extremely high rate, consider the application of ammonium nitrate at 100% fi rst year 

release, which would supply 769 lb/ac (Line A) of immediately available nitrogen. Recalculating 

fertilizer rates using a more realistic rate of 50 lb/ac available nitrogen needed the fi rst year 

after application (Line F), bulk fertilizer application rates would be 1,563 lb/ac (Line H). At this 

new rate, the site would have suffi cient fi rst- and second-year supplies of nitrogen, but lack 

adequate nitrogen the following years. The remaining defi cit to meet long-term nitrogen 

targets would be approximately 644 lb/ac, which must be supplied through later applications 

of fertilizer or other carriers of nitrogen (topsoil, compost, biosolids, wood waste, mulch, and 

nitrogen-fi xing plants). A nutrient strategy should be built around reducing nitrogen defi cits 

over time.

The process outlined in Figure 10.5 can be used for other defi cient nutrients. Understanding 

the availability of other nutrients is problematic. Many nutrients become fi xed in the soils and 

their availability is dependent on highly variable factors such as soil texture, pH, and placement 

in the soil. It is a reasonable assumption that unless the soils are sandy or very rocky, that all 

nutrients, aside from nitrate or ammonium forms of nitrogen, are relatively unavailable the fi rst 

year after application. With time, however, they will slowly become available.

10.1.1.7 Determine Timing and Frequency

The primary reason to fertilize is to supply nutrients during periods when plants can take 

them up for growth. The demand for nutrients changes throughout the year depending on 

the physiological state of each plant. In nursery settings, fertilizers are adjusted throughout 

the year at rates and formulations that correspond to the requirements of the plant. While we 

do not have that capability in wildland settings, we can use the fertilizers available to us more 

wisely by applying our understanding of how the assortment of fertilizers function in meeting 

the nutrient requirements of plant communities. At least two plant growth phases should be 

considered in the timing of fertilizer application – 1) seed germination, and plant establishment 

and 2) post plant establishment. 

Seed Germination and Plant Establishment Phase – Traditionally, fast-release fertilizers have 

often been applied at high rates in the fall during the seed sowing operation. This practice 

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191
is a quick and easy way to apply fertilizers. However, the timing can result in ineff ective and 

wasteful use of fertilizers (Figure 10.6B) (Dancer 1975). In addition, application of fast-release 

fertilizers at this time can potentially pollute water sources. Slow-release fertilizers are more 

appropriate for seed sowing in the fall because much of the fertilizer should last through the 

winter, releasing nutrients in the spring (Figure 10.6D).

Perennial grasses and forbs do not require high levels of nitrogen for germination and early 

establishment (Reeder and Sabey 1987). In fact, elevated levels of available nitrogen can be a 

problem because it encourages the rapid establishment and growth of annual weed species over 

slower-growing perennial grass and forbs (McLendon and Redente 1992; Claassen and Marler 

1998). Applying high rates of fertilizers during germination and early seedling establishment 

should be reconsidered in terms of how much fertilizer is actually needed in the establishment 

phase and how much will be available later for plant growth (See Section 10.1.1.6). 

One strategy is to apply little or no fertilizer during sowing and wait until seeds have germinated 

and grown into small seedlings before fertilizers are applied (Figure 10.6C). This strategy assures 

that nutrients are available when the seedlings actually need them, not before. Fertilizers 

applied as slow-release form are preferred because they have less potential for causing salt 

damage when applied over emerging seedlings. Another strategy is to wait until the following 

fall (Figure 10.6E) or spring (Figure 10.6F) of the second year to fertilize. 

Post-Establishment – Once vegetation is established (one or two years after sowing), fertilizers 

can be applied at higher rates with the assurance that nutrients will be taken up by the plants. 

Slow- and fast-release fertilizers can be combined to provide short- and long-term nutrient 

requirements (Figure 10.6 E and F). Spring applications of fast-release fertilizers are more 

eff ective than fall application because of the higher nutrient requirements of growing plants 

during that period (Figure 10.6F). Spring applications also have less risk of damaging vegetation 

through fertilizer salts because precipitation in the spring is typically frequent enough to wash 

fertilizers from the foliage. It is always prudent to check the conductivity of a fertilizer solution 

being applied over existing vegetation to avoid salt damage. A conductivity meter can be used 

to measure the conductivity of the solution (See Section 5.5.5). If rates exceed 3,500 mS/cm, then 

diluting the solution or applying the fertilizer during rainy weather is advised. Fall application 

of fertilizers should be done at lower rates and early enough for nutrients to be utilized by the 

growing vegetation. Fertilizer rates can be adjusted based on plant phenology or dormancy to 

minimize salt damage. Fertilizing dormant plants is also a possible way to minimize damage. 

10.1.1.8 Select Fertilizer Application Method

Since nutrients have varying degrees of mobility (nitrogen is highly mobile; phosphorus and 

many micronutrients are relatively immobile), how fertilizers are applied will determine how 

accessible nutrients are to the root system. If nutrients are highly mobile, the easiest and 

least expensive method is to apply fertilizer to the soil surface, or broadcast, to allow rainfall 

or snowmelt to release and move nutrients into the soil. A more diffi cult, yet more eff ective 

application method for immobile nutrients is to incorporate, or mix, fertilizers into the 

soil surface so fertilizer granules are uniformly distributed within the soil and accessible by 

root systems. 

Broadcast Fertilizer Application – For fertilizers with highly mobile nutrients, such as 

nitrogen and sulfur, broadcast application on the soil surface is an appropriate practice. 

For immobile nutrients, broadcast fertilizer application can be relatively ineff ective. These 

nutrients often become immobilized at the soil surface and are very slow to move into the 

rooting zone where they can be accessed. Depending on soil characteristics, such as pH and 

clay content, some immobile nutrients will take years to move only a few inches from the point 

of fertilizer placement. 

There are a variety of dry fertilizer spreaders available, from hand-operated to tractor-mounted. 

Most equipment is limited to moderate slope gradients (less than 1V:2H). With all forms of 

spreaders, they must be calibrated before they are used to assure that the correct rates are 

being applied. 

Hydroseeding equipment can be used to apply fertilizer in the same operation with seeds, 

tackifi ers, and hydromulch (See Section 10.3.2, Hydroseeding). This equipment can also be 

used solely to apply fertilizers, especially after vegetation has become established. A great 

advantage to using hydroseeding equipment is that it can uniformly spread fertilizers on steep 

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192
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Figure 10.6 – Fertilizers should be applied during seasons, and at rates and formulations that 

release nutrients when native plants can effi ciently draw them from the soil. The following are 

strategies for applying slow and fast release fertilizers.

Plant Growth

Fall Winter Spring Summer Fall Sowing Germination

A

Fall Winter Spring Summer Fall

B

N Availability

Time Time N Availability

Fast-release

Plant Growth

A. When seeding occurs in the fall, seeds 

typically do not germinate until the 

following spring, at which time there is 

rapid growth. During the summer, growth 

rates slow. Growth rates accelerate again in 

the fall. 

C. Fast-release fertilizer applied in the spring 

after plants are established is more eff ective 

because plants are rapidly growing and can 

take up nutrients. There are fewer storms in 

the spring to leach nutrients from the soil.

E. Once vegetation has become established, 

plant growth will take place in the fall. 

Fertilizers applied at this time will be taken 

up by growing vegetation. Since slowrelease fertilizers might not be immediately 

available, small amounts of fast-release 

fertilizers can be added to give immediate 

release of nutrients.

B. When fast-release fertilizers (dashed line) 

are applied in the fall during seeding, 

fertilizers move into the soil with fall rains. 

However, there is no vegetation to take up 

the nutrients. Mobile nutrients, such as 

nitrogen, are leached and unavailable in 

the spring when the establishing plants 

require them. 

D. Slow-release fertilizers (dotted line) release 

nutrients at a much slower rate. When 

they are applied in the fall, most of the 

nutrients should still be available in the 

following spring.

F. Slow- and fast-release fertilizers can be 

applied in the early spring before rapid 

root and vegetative growth. Fast-release 

fertilizers can supplement slow-release 

fertilizers by supplying immediately 

available nutrients.

Fall Winter Spring Summer Fall

C

Fall Winter Spring Summer Fall

D

Time Time

N AvailabilityN Availability

Fast-release

Plant Growth

Slow-release

Plant Growth

Fall Winter Spring Summer Fall

E

Fall Winter Spring Summer Fall

F

N AvailabilityN Availability

Fast-release

Plant Growth

Slow-release

Fast-release

Plant Growth

Slow-release

193
slopes and a variety of topographies. In addition, a combination of fertilizers can be easily mixed 

in the hydroseed tank and applied at relatively even proportions because they are in a solution. 

This is especially useful for applying small quantities of fertilizer, such as micronutrients, which 

are diffi cult to spread evenly over large areas. 

Fertilizer Incorporation – It is important that nutrients that are defi cient and have low mobility 

be incorporated into the soil prior to sowing or planting. Incorporation is possible on gentle 

slopes, but becomes very diffi cult with increasing slope gradients because of equipment 

limitations. On sites where fertilizers containing immobile nutrients cannot be incorporated, 

an alternative is to create roughened soil surfaces (See Section 10.1.2, Tillage) prior to fertilizer 

application. Broadcast fertilizers will accumulate in the depressions of the surface. As soil 

gradually moves into the depressions over time (through water erosion or surface ravel), the 

broadcast fertilizers will become covered with soil. When this happens, immobile nutrients 

are accessible by roots and nutrient uptake is possible. Surface roughening also reduces the 

potential for fertilizers to move off -slope through erosion.

Some agricultural spreaders, called fertilizer banders or injectors, are designed to place 

fertilizer, or other soil amendments including mycorrhizae, at varying depths in the soil. Usually 

this equipment has a ripping shank or tine that loosens the soil, followed by a tube that drops 

the fertilizer, and coulters or rollers that close up the furrow. As the bander is pulled through the 

soil, a line, or band, of fertilizer is created. Sowing and banding are often combined in one piece 

of equipment and applied at the same time. Fertilizer banders were developed for agricultural 

use and are limited by rock content and slope gradients. However, there are injectors that have 

been develop for wildland conditions (St John 1995).

The most common approach to incorporating fertilizer is accomplished in two operations, 

broadcasting fertilizer on the soil surface and tilling it into the soil. Hydroseeders and broadcast 

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Inset 10.1 – Spot-Fertilizing Seedlings

Fertilizing shrub or tree seedlings is done by placing 

fertilizer in each seedling hole or on the soil surface 

after each seedling has been planted. This practice 

has some risks, because fertilizers release salts which 

can damage roots. Studies have shown that placing 

fertilizers or liming materials in the planting hole or on 

the soil surface around seedlings at the time of planting 

can signifi cantly decrease seedling survival, especially 

on droughty sites (Nursery Technical Cooperative 

2004; Jacobs and others 2004; Walker 2002). 

To reduce the likelihood of seedling damage, follow 

these practices:

 · Assess the need for fertilizer (do not apply if 

nutrient levels are adequate).

 · Use slow release fertilizers with low 

salt indexes.

 · Use low rates of fertilizer if applying at the time of planting.

 · If applying in seedling hole at planting, use low fertilizer rates and place fertilizer to 

the side at least 3 inches away from the root system.

 · Preferably broadcast fertilizers on the soil surface after seedlings are 

well established.

When slow-release fertilizers are spread around well-established seedlings (several years 

after planting), seedlings often respond favorably, especially on highly disturbed sites. 

Walker (2005) showed that slow-release fertilizers broadcasted three years after seedlings 

were planted, increased stem diameter and shoot volume over the control seedlings by 

143% and 104% respectively fi ve years after the fertilizer was applied. In this study, rates of 

.05 grams of nitrogen per seedling showed the greatest response (at 8% nitrogen analysis, 

this would be over a half pound of bulk slow-release fertilizer per plant).

194
fertilizer spreaders, as discussed above, are means of applying the fertilizer evenly over the site, 

then the fertilizer is tilled into the soil using equipment outlined in Section 10.1.2, Tillage. 

10.1.2 TILLAGE

10.1.2.1 Introduction

Tillage is defi ned in this section as any mechanical action applied to the soil for the purposes 

of long-term control of soil erosion and reestablishment of native plant communities. Tillage 

equipment was developed for agricultural soils and has limited applicability for steep, rocky 

sites typically encountered in wildland revegetation. This section will discuss the agricultural 

equipment that can be used for wildland revegetation as well as equipment specifi cally 

developed for these extreme conditions.

There are several reasons to use tillage in a revegetation project, including to: 

 · Shatter compacted soils,

 · Incorporate soil amendments, and

 · Roughen soil surfaces.

These objectives often overlap. For example, incorporating organic matter also loosens 

compacted soils and roughens soil surfaces. Identifying the objectives for the project will 

lead to selecting and eff ectively using the appropriate equipment to achieve the desired 

soil conditions (Table 10.3). 

10.1.2.2 Shatter Compacted Soils 

One of the primary purposes for tilling is to loosen compacted soils. When performed correctly, 

tillage can increase porosity in the rooting zone, increase infi ltration rates, and increase surface 

roughness. For revegetation work associated with road construction and road obliteration, 

tillage to break up deep compaction is important for reestablishing plant communities. 

Shattering compaction at depths of at least 2 feet is essential for the healthy growth of most 

perennial plant species. Without this measure, it will take many decades for deep compaction 

to recover its original bulk density (Wert and Thomas 1981; Froehlich and others 1983). In a 

review of tillage projects on rangeland soils, Giff ord (1975) found that deep tillage greatly 

reduced runoff , while shallow tillage had little eff ect. 

Tillage alone will not return a soil to its original bulk density or hydrologic function (Figure 

10.7), nor will the eff ects of tillage last indefi nitely, especially in non-cohesive soils (Onstad and 

others 1984). There are many factors that aff ect the return to bulk densities and infi ltration 

rates typical of undisturbed reference sites. These include the type of tillage equipment used, 

penetration depth, soil moisture during tillage, soil texture, presence of topsoil, and organic 

matter content.

There are two fundamentally diff erent equipment designs for reducing compaction. One 

design simply lifts and drops soil in place, shattering compacted soil in the process. This type 

of equipment includes rock rippers, subsoilers, and “winged” subsoilers. The second design 

churns and mixes the soil. Equipment that falls into this category includes disk harrows, plows, 

spaders, and attachments to excavators. This type of equipment can also incorporate soil 

amendments, like organic matter or fertilizers, in the same operation, and will be discussed in 

Section 10.1.2.3.

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Shattering

OBJECTIVES

TYPE OF TILLAGE

Good

Good

Poor

Loosen compacted soil

Roughen surface

Incorporate amendments

Good

Good

Good

Poor

Good

Poor

Mixing Imprinting

Rippers & subsoilers Disks, plows,

excavator attachments

Dixon imprinter,

excavator attachments,

trackwalking

Table 10.3 – The appropriate tillage equipment for the project depends on project objectives.

195
The terms subsoiling and ripping are used interchangeably to describe soil shattering 

operations. Soil shattering involves pulling one tooth, or a set of teeth, at various depths through 

the soil to break up compaction created by equipment traffi c. The rock ripper is a common tool 

found on most construction sites. When used to break up compaction, one or two large ripper 

tines are typically pulled behind a large bulldozer at 1 to 3 ft soil depths. While this equipment 

will break up compaction in portions of the soil where the ripper tines have been dragged, 

it does not eff ectively fracture the compacted 

soil between the ripper tine paths (Andrus and 

Froehlich 1983). The eff ectiveness of rippers can 

be increased by multiple passes through the 

soil or by adding tines to the toolbar. Even on 

small machines, up to 5 tines can be added to 

increase soil shatter.

Rippers have also been adapted to increase 

soil lift between tine paths by welding wide 

metal wings to the bottom of each tine. These 

wings are angled upwards so the soil between 

the tines has greater lift, and therefore greater 

shatter when the soil drops behind the wing. 

When two or more tines are placed together on a 

toolbar, they work in tandem to more eff ectively 

break up compaction. The resulting equipment 

is called the “winged” subsoiler (Figure 10.8). 

Andrus and Froehlich (1983) found that the 

winged subsoiler was a far more eff ective tool 

for breaking up compaction. This equipment 

fractured over 80% of the compaction in 

several operational tests, as compared to 18% 

to 43% for rock rippers and 38% for brush rakes. 

However, winged subsoilers are not practical 

in all soils, especially those with high rock 

fragments, buried wood, or slopes greater than 

3H:1V gradients.

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Figure 10.8 – Soil shattering becomes 

more eff ective when wings are mounted 

on subsoil tines. This equipment is called 

a winged subsoiler. Photo courtesy Brent 

Roath.

Figure 10.7 – Short-term benefi ts of ripping (using a winged subsoiler) and mulching road 

surfaces vary by soil type, as shown in rainfall simulation tests on sites in northern Idaho. 

Granitic soils responded to ripping and mulching with increased permeability during the 

fi rst storm, but permeability rates returned to near pre-treatments rates with successive 

rainfall events. Metamorphic soils reacted positively to both treatments and maintained 

high permeability rates after three rainfall events. Mulching improved permeability in 

both soil types. In fact, for metamorphic soils, the combination of ripping and mulching 

increased permeability to rates that were typical of lightly disturbed forest soils (adapted from 

Luce 1997).

Ripped & Mulched

Ripped

Prior to Ripping

Permeability rates for

lightly disturbed forest soils

100 year rainfall rate

Snowmelt rate

Granitic Metasedimentary

Rainfall Event Rainfall Event

Inches per Hour3

2

1

1st 2nd 3rd 1st 2nd 3rd

196
Achieving good shatter at deeper soil 

depths requires that tillage equipment be 

adjusted for site-specifi c soil conditions, 

especially soil texture, soil moisture, and 

large rock content. Soils should not be 

too moist during ripping because the 

tines will slice through the soil, causing 

very little soil shatter. Subsoiling when 

soils are extremely dry can bring up large 

blocks of soils, especially when the soils 

are high in clays (cohesive soils). 

The winged subsoiler and rock ripper 

should be adjusted to meet the soil 

conditions of the site. Making the 

proper adjustments can lead to greater 

shatter and more effi cient use of tractor 

equipment. These adjustments include:

 · Tine depth,

 · Tine spacing,

 · Number of tines, and

 · Wing width and angle (for winged 

subsoiler).

Tines should be set above the critical 

depth for the condition of the soil. If tines 

are set below this depth, the tines will 

not shatter the soil (Figure 10.9B). The 

critical depth changes for soil type and 

tine confi guration. Soils high in clays with 

high soil moisture have shallower critical 

depths (Andrus and Froehlich 1983). The 

closer the spacing of tines, the greater 

the shattering. The more tines that are 

placed on a toolbar, the more area of soil 

can be shattered. However, where large 

rocks or large slash are present, closely 

spaced tines will drag these materials 

out of the ground. Three to fi ve tines are 

typically used for most soil types. Wing 

size, angle, and shape of the tines all play 

a role in breaking up compaction (See 

Inset 10.2 for specifi cations for winged 

subsoiler).

Typical settings for rock ripper and winged 

subsoiler equipment confi gurations are 

shown in Table 10.4. These are suggested 

settings and should not be applied 

without fi rst monitoring the results of the equipment on the project soils. The most direct 

method for monitoring soil shatter is to measure the depth to the compacted soil with a soil 

penetrometer or shovel (See Section 5.3.3.1). Immediately after a pass is made with the tillage 

equipment, the penetrometer is pushed into the soil and the depth to the compacted layer is 

recorded. Measurements are taken every 6 inches across a small transect perpendicular to the 

direction of the tractor and spanning the width of the tillage disturbance. Plotting the depths 

to compaction on graph paper gives a cross-section of the shattering pattern (Figure 10.9 is 

an example of plotting soil shatter). If the shattering pattern is inadequate, adjustments can 

be made to the tine depth, tine spacing, and angle of the wing. If these adjustments fail to 

increase soil shatter, a second and even third pass by the ripper or winged subsoiler should be 

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Figure 10.9 – The eff ectiveness of subsoiling 

or ripping equipment to shatter compacted 

soil is a function of tine depth, number of 

tines, distance between tines, and wing 

confi guration. Pulling a single tine (A) above 

a critical depth does some soil shattering as 

compared to a single tine ripping deeper than 

a critical depth (B). Placing 3 or more tines 

together (C) can be more eff ective than one 

tine, but tine spacing should not be too far 

apart or soils between the tines will not be 

shattered (D). Attaching wings to the tines 

is very eff ective in shattering compaction 

between the tines (E) (modifi ed after Andrus 

and Froehlich 1983).

0

1’

2’ Critical

Depth

0

1’

2’

0

1’

2’

0

1’

2’

2’ 1’ 1’0 2’

A. Single tine

C. Three tines

D. Tines—too far apart

E. Two tines (winged)

B. Single tine—too deep

197
considered. Successive passes should be made at 45 to 90° angles from the fi rst pass to achieve 

the greatest benefi t. 

A general rule for tillage work is to operate equipment on the contour to reduce the potential of 

water concentrating in the paths of the furrows and creating soil erosion problems. Operating 

equipment on the contour (cross slope) is limited to gentler slopes (Table 10.4). To optimize 

the use of equipment on steep slopes, down-slope operation of equipment must not create 

long, continuous furrows. It is also important to consider that if cuts and fi lls are left less 

compacted, there will be deeper rills and gullies created if concentrated fl ows of water are 

directed onto these slopes. These features are unsightly and can deliver high quantities of 

sediment to watercourses. Therefore, on slopes that have been tilled, it is important to redirect 

any concentrated fl ow of water that might enter the top of the cut to areas that are designed to 

handle this water. While it is not the job of the revegetation specialist to walk the tops of cuts 

and fi lls to determine whether concentrated water might fl ow into areas that are not designed 

for it, the success of the tillage project might depend on it.

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Disk diameter

Number of disks

Average disk weight

Disk arrangement Disk

harrow

Brush

blade

Rock

rippers

Wings

of

subsoilers

40 - 50 in.

6 -12

>1,800 lbs

Offset gangs, independent disks

Max slope (cross slope travel) <5:1 H:V

Max slope (down slope travel) 5:1 H:V

Tine spacing 22 - 26 in.

Tine depth <20 in.

Max slope (cross slope travel) >5:1 H:V

Max slope (down slope travel)

Tine spacing

Ripping depth

Number of tines

3:1 H:V

Max slope (cross slope travel) <5:1 H:V

Max slope (down slope travel) 2.5:1 H:V

Ripping depth 18 - 22 in.

Number of tines 3 - 4

Tine spacing 30 - 40 in.

Wing width 12 - 24 in.

Max slope (cross slope travel) <5:1 H:V

Max slope (down slope travel) 2.5:1 H:V

Wing angle 10 - 60 ̊

24 - 30 in. (one pass)

40 - 48 in. (two passes)

20 -24 in.

5 (one pass)

3 (two pass)

Item Implement Feature Recommended Design

Table 10.4 – Recommended design features for some tillage equipment (modifi ed after 

Andrus and Froehlich 1983; Froehlich and Miles 1984).

198
Most soil shattering equipment is attached to a 

tractor toolbar and is limited to slope gradients 

of 3H:1V or less. Subsoilers and rippers are best 

used for projects that consist of gentle terrain 

or obliterated road sections. Newer equipment, 

such as the subsoiling grapple rake, has been 

developed to overcome these limitations. 

Attached to the arm of an excavator, this 

equipment can reach 35 feet up and down 

slope and specifi cally rip targeted areas of 

compacted soil (Figure 10.10). 

10.1.2.3 Incorporate Soil Amendments

Tilling is used to incorporate fertilizers, 

organic matter, lime, and other amendments 

evenly throughout the soil, while loosening 

compacted soils. Tilling with these objectives 

requires equipment that mixes soil, such as 

plows, tillers, disks, chisels, and soil spaders. 

This equipment is tractor-drawn and limited to 

gentle slope gradients (5H:1V or greater) and 

soils low in rock fragments. These tools are not 

designed to break up deep compaction. Under 

most disturbed soil conditions, the best that 

can be expected this equipment is tillage to a 

depth of 8 to 12 inches. 

Rippers and subsoilers are not very eff ective 

in incorporating materials such as fertilizers 

or organic matter into the soil. Nevertheless, spreading mulch on the soil surface prior to 

ripping or subsoiling usually incorporates enough organic matter into the soil surface to 

enhance infi ltration rates (Luce 1997). In the same manner, fertilizers applied to the soil surface, 

especially those containing immobile nutrients, will be mixed into the top several inches of 

soil and made available to surface roots. On projects where topsoil has been salvaged and 

reapplied, subsoilers or rippers are the preferred equipment. Using equipment that mixes soils 

runs the risk of incorporating salvaged topsoil with the infertile subsoil. 

A more recent set of specialized revegetation tools that mix and incorporate amendments have 

been developed for the tracked excavator. The arm of the excavator can reach 35 to 40 feet on 

steep cut and fi ll slopes and work soils that were previously inaccessible to most equipment. 

The simplest excavator attachment is the bucket which can be used to move topsoil or organic 

matter to concentrated locations and creating mounds or planting islands (See Section 

10.1.8). When islands are created for deep-rooted species, such as shrubs and trees, soil can be 

excavated several feet deep with the excavator bucket and incorporated with organic matter 

amendments to create a deep rooting profi le. 

The subsoiler grapple rake (Figure 10.10) adds several design features to the excavator bucket. 

In addition to mixing organic amendments into the soil, the subsoiler grapple rake can remove 

large rock with the grapples and loosen soils with the winged subsoiling tines.

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Figure 10.10 – The subsoiling grapple 

rake is a quick-mounting attachment 

to excavating machinery that combines 

several operations in one: (A) subsoiling 

with winged tines, (B) soil incorporation 

with bucket, and (C) removal of rock and 

slash with grapples (Photo courtesy of 

Mike Karr, Umpqua National Forest).

A

B

C

Inset 10.2 – Contract Specifi cations for a Winged Subsoiler

A winged subsoiler consists of a self-drafting, winged subsoiler on a dolly mount, sized for 

use with a D-7 tractor. The unit consists of three winged ripper tines capable of extending 12 

to 34 inches below the draw bar. Wings shall be at least 20 inches wide with a 2 inch lift of the 

wings from horizontal. Tines shall have an individual tripping mechanism that automatically 

resets; tine spacing must be adjustable and individual tines must be removable. Various 

wing patterns must be available and easily interchangeable. Implement must be capable of 

achieving maximum fracture of compacted soils (minimum 24 inches) in one pass (Adapted 

from Wenatchee National Forest contract specifi cations).

199
10.1.2.4 Roughen Soil Surfaces

Tilling is often done to roughen the soil surface for erosion control and to create a more 

optimum seedbed (See Section 5.6.7). The micro-topography of a roughened surface consists 

of discontinuous ridges and valleys. The valleys become the catch basins for seeds and surface 

runoff . Seeds have greater opportunities to germinate and become established in the microvalleys because of increased moisture, higher humidity, protection from the wind, and shelter 

from the sun. Surface roughening is a side benefi t of the mixing and shattering operations 

discussed above in Section 10.1.2.2 and Section 10.1.2.3. Roughening is also accomplished by 

either scarifying or imprinting operations. 

Scarifi cation is the shallow loosening of the soil surface using brush blades, harrows, chains, 

disks, and chisels. Because it only loosens the soil surface several inches, the benefi ts for 

revegetation are only seen during seed germination and early seedling establishment. Once 

root systems hit the hard compacted layer several inches below the loosened surface, plant 

growth is curtailed.

Imprinting is a form of surface tillage that leaves the soil with a pattern of ridges and valleys. 

The equipment applies a downward compressive force to a metal mold, leaving an impression 

on the soil surface. The most basic type of imprinting is trackwalking (Figure 10.11). In this 

operation, tracked equipment are “walked” up and down cut and fi ll slopes, leaving a pattern 

of tractor cleat imprints on the soil surface no deeper than an inch or two deep. Imprinting 

methods that are tractor-based are restricted by slope gradients. Since heavy equipment is 

used, trackwalking can compact soils. Compaction is not often considered when selecting 

trackwalking practices because soils of most construction sites are already very compacted, 

and trackwalking is unlikely to signifi cantly increase compaction. This is one reason why 

trackwalking has been considered benefi cial for erosion control and revegetation because it 

does create a somewhat better “short-term” growing environment and reduces surface erosion 

and sedimentation on a very poor site. 

An alternative to trackwalking is the use of the bucket of an excavator to pack and imprint 

the soil surface. Diff erent patterns of steel “teeth” can be welded on the face of the bucket 

to achieve the desired surface micro-relief. Figure 10.12 shows a makeshift imprinter, which is 

simply 4 strips of angle iron welded to a bucket to create a pattern of 3-inch deep impressions. 

The excavator in this example can move topsoil in place, shape the cut and fi ll slopes, and 

imprint the surface, all with one operation.

If the last operation on a construction site is to subsoil or rip soils 1.5 to 2 ft deep and leave 

the soil surface in a roughened condition prior to revegetation, trackwalking would be 

more detrimental than benefi cial on most soils. The tractor used to create imprints would 

compact the tilled soil leaving the surface smoother (less rough) than if left alone. If one of 

the construction objectives is to leave the construction soils in non-compacted condition, 

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Figure 10.12 – An alternative form of 

imprinting road cuts and fi lls that does 

not compact soils is welding angle iron 

onto the bucket of an excavator. As the 

excavator pulls topsoil into place and 

contours the slope, it presses the face of 

the bucket into the soil surface to form 

surface imprints.

Figure 10.11 – Trackwalking creates 

imprints on the soil surface, but will also 

compact surface and subsurface soils.

200
the use of trackwalking should be seriously weighed against the long-term impacts to plant 

establishment and growth. Compaction will aff ect surface infi ltration and runoff , therefore, 

trackwalking should be critically evaluated for its potential increase in soil erosion. Rainfall 

simulation tests can be run on sites near the construction project that have been trackwalked 

and compared with those that have been left in an uncompacted state to determine the eff ects 

on runoff and soil erosion (Hogan and others 2007).

Specialized imprinters have been developed for rangeland restoration. For example, the 

“Dixon” imprinter was developed to restore perennial grasses for rangelands in Arizona and 

other arid states. It consists of a roller with large conical metal “teeth” that is pulled behind a 

tractor. The imprinter creates a pattern of V-shaped troughs, 4 to 7 inches deep, encompassing 

approximately 1 ft2 area (Dixon and Carr 2001a, 2001b). These imprints are substantially larger 

and deeper than those created by trackwalking, with greater longevity. This equipment 

also has a set of ripping shanks attached to the tractor that shatters deeper compaction 

before imprinting. 

10.1.3 MULCHES 

10.1.3.1 Introduction

Mulch is defi ned as a protective material placed on the soil surface to prevent evaporation, 

moderate surface temperatures, prevent weed establishment, enrich the soil, and reduce 

erosion. Mulches therefore have many functions or roles in the recovery of native vegetation to 

a disturbed site. But confusion often arises around the use of mulches on revegetation projects 

unless the reasons for using them in a project are clearly defi ned. In this discussion, we have 

grouped mulches into four uses based on revegetation objectives: 

 · Seed Covering,

 · Seedling Mulch,

 · Soil Improvement, and

 · Seed Supply.

For most projects, mulches are used to meet more than one objective. Problems arise when 

the methods for applying overlapping objectives are not compatible. For example, erosion 

control objectives and seed covering objectives go hand-in-hand because the soil surface 

needs to be stable for seeds to germinate and grow into young seedlings. In turn, the surface 

ultimately becomes stable through the establishment of young plants. Yet erosion control 

products and practices that are eff ective for controlling surface erosion are not always optimal 

for establishing vegetation. For this reason, it is important to understand the objectives for 

mulching and to integrate them into a comprehensive strategy when selecting mulch types 

and application methods. 

This section discusses the objectives for applying mulches and the potential mulch sources. 

We have left the discussion of the eff ectiveness of mulches for erosion control and surface 

stabilization to the many publications and research devoted to this topic and focus primarily 

on the characteristics of mulches for plant establishment. 

10.1.3.2 Seed Covering

One of the principal reasons for applying mulch is to enhance seed germination and early 

seedling establishment. During this critical period, desirable mulches will:

 · Protect seeds and young seedlings from soil splash, sheet erosion, and freeze-thaw; 

 · Keep seeds moist during germination;

 · Moderate surface temperatures during germination;

 · Keep young seedlings from drying out; and

 · Prevent salts from wicking to the surface and harming newly germinating seedlings.

The characteristics of mulch materials that make ideal seed coverings are those that protect 

seeds from drying winds, solar radiation, high evapotranspiration rates, and surface erosion 

while still allowing seeds to germinate and grow through the mulch into healthy seedlings. 

Long-fi bered mulches, such as straw, wood strands, pine needles, and ground or chipped wood, 

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placed at the appropriate thickness, 

usually meet these characteristics. 

When applied correctly, the strands 

of long-fi bered mulch loosely bridge 

on top of each other, much like “pickup-sticks,” forming large air spaces 

or pores (Figure 10.13). Large pores 

function much like the air spaces in 

building insulation by moderating 

extreme temperatures. 

Compared to short-fi bered mulches, 

such hydromulch, long-fi bered 

mulches can be applied at greater 

thicknesses, which help maintain 

surface soil moisture and higher 

humidity around germinating seeds 

and emerging seedlings. In addition, 

long-fi bered mulches can mitigate 

the eff ects of frost heaving at the 

soil surface (Kay 1978), signifi cantly 

reduce high surface temperatures 

(Slick and Curtis 1985), and allow 

sunlight penetration, which enhances seed germination and seedling establishment. Large 

pores created by long-fi bered mulches also allow better gas exchange between the soil and 

atmosphere (Borland 1990). 

Short-fi bered mulches, on the other hand, have smaller pores and form denser seed covers. 

These materials are typically applied thinly (Figure 10.14), so they off er less insulation than longfi bered mulches and therefore have less value as a seed covering. Some researchers suggest 

that very fi ne textured mulches can actually increase surface evaporation by wicking moisture 

from the soil to the surface of the mulch (Slick and Curtis 1985; Borland 1990; Bainbridge and 

others 2001). Short-fi bered mulches are eff ective as an erosion control cover, but are considered 

inferior to long-fi bered mulches for germination and early seedling establishment (Kill and 

Foote 1971; Meyer and others 1971; Kay 1974, 1978, 1983; Racey and Raitanen 1983; Dyer 1984; 

Wolf and others 1984; Norland 2000).

Erosion mats can perform well as seed 

covers (See Section 10.1.3.8). These materials 

come in rolls or sheets, which are laid out on 

disturbed soils and anchored in place after 

seeds have been sown. They are composed 

of such materials as polypropylene, straw, 

coconut, hay, wood excelsior, and jute. Good 

characteristics of erosion mats for seed 

germination and early seedling growth are 

those with enough loft, or porosity, to create 

a micro-environment for seed germination 

while allowing some sunlight to penetrate 

to the surface of the soil (Figure 10.15).

On sites where vegetation is expected to 

take several years to establish (e.g., arid, 

high elevation sites), it is important to apply 

a mulch with a longevity of more than one 

year. Materials with greatest longevity are 

most long-fi bered wood mulches, as well 

as erosion mats made from polypropylene. 

Straw, hay, and short-fi bered wood 

products are less likely to be present after 

the fi rst year.

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Figure 10.14 – Hydromulch with tackifi er 

can stabilize the soil surface for up to a 

year, but does not necessarily create an 

optimum environment for germinating 

seeds. The short-fi bered textures typically 

form a covering that is too thin to 

maintain moisture around the seeds 

during germination when the weather is 

dry. The hydromulch (dyed with a green 

tracer) shown in this picture is applied at 

approximately 1,500 lb/ac.

Figure 10.13 – Long-fi bered mulches, like wood 

strands shown below, create a good growing 

environment because seeds and seedlings are 

protected from excessive drying during germination 

and early seedling establishment. On sites where 

freeze-thaw is prevalent, long-fi bered mulches can 

insulate the soil and protect emerging seedlings.

202
Mulching for seed covering is critical on sites that have: 1) high evapotranspiration rates during 

germination, 2) unstable soil surfaces, 3) susceptibility to freeze-thaw, and 4) high soil pH. It 

is less important on sites where soil surfaces do not dry out during seed germination or on 

projects where seeds have been covered by soil. 

10.1.3.3 Seedling Mulch

Mulch is placed around newly planted or established plants to improve survival and growing 

conditions by:

 · Reducing surface evaporation,

 · Preventing the establishment of competing vegetation,

 · Moderating surface temperatures, and

· Allowing water infi ltration. 

Studies have shown that survival and growth of young trees are significantly increased by 

applying mulches around seedlings at the time of planting (DeByle 1969; Lowenstein and 

Ptikin 1970; Davies 1988a, 1988b). Mulching around seedlings results in the greatest benefi t 

on hot and dry sites (typically south and west aspects) and sites with aggressive competing 

vegetation. It is less important to mulch around seedlings on sites that have a low potential for 

establishing competing vegetation the fi rst several years after planting. Mulching is also less 

critical on sites that have low evapotranspiration rates or high summer rainfall. 

Seedling mulches are applied either as an organic aggregate or as sheets. Organic aggregate 

mulches consist of shredded or chipped wood derived from bark, wood, branches, sawdust, 

or lawn clippings applied deeply around seedlings. Sheet mulches are large pieces of nonpermeable or slightly permeable materials made from translucent plastic, newspaper, or 

geotextiles (woven fabrics) that are anchored around planted seedlings (Figure 10.16).

Sheet Mulches – A variety of sheet mulches are available commercially. These mulches are 

popular because of the relative ease of transport and installation. The eff ectiveness of sheet 

mulches increases with the size of the sheets. For most hot, dry sites, a 2.5 by 2.5 ft sheet is 

considered to be the minimum dimension (Cleary and others 1988). On harsher sites, 3 by 3 ft 

or even 4 by 4 ft sheets are necessary to control competing vegetation. When purchasing and 

installing sheet mulches, the following should be considered (after Davies 1988a, 1988b):

1) Select the right size. The size of the mulch should be based on site conditions and the 

type and amount of competing vegetation. A hot, south-facing site with full cover of 

competing grasses will need a large sheet mulch; a north-facing slope with scattered 

forbs and grasses will suffi ce with the smallest size.

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Figure 10.16 – Sheet mulches come in a 

variety of materials, such as the paper/

cardboard product shown in this picture. 

The size of the sheet mulch must be large 

enough to keep competing vegetation 

away from the seedling. The 3 by 3 ft sheet 

mulch shown around this Pacifi c madrone 

(Arbutus menziesii) seedling is the 

minimum size for this site.

Figure 10.15 – Erosion mats can be good 

seed covers. Mats with the highest loft 

create the best microenvironment for seed 

germination while allowing some sunlight 

to penetrate to the surface of the soil.

203
2) Order only opaque materials.

Translucent materials should not 

be used as sheet mulches because 

weed seeds can germinate and 

grow under these materials. During 

the summer, surface temperatures 

under translucent materials can be 

lethal to seedling roots.

3) Use sheet mulches with long life 

spans. The durability of sheet mulch 

should be at least 3 years. It often 

takes 3 to 5 years for seedlings to 

become established on hot, dry sites 

(Cleary and others 1988). 

4) Weed or scalp around seedlings 

prior to installation. Sheet mulch 

cannot be installed properly without 

competing vegetation being 

completely removed. 

5) Mulch immediately after planting. 

Waiting until later in the spring to 

mulch runs the risk that competing 

vegetation will have depleted 

soil moisture, thereby making the 

mulch ineff ective during the fi rst 

growing season.

6) Securely stake or anchor all 

corners of the mulch. The sides of 

the mulch sheets can pull out easily 

by wind, animals, or competing 

vegetation growing under the mulch sheets. It is important that, at a minimum, the 

corners are staked. For greatest eff ectiveness, bury all edges of the sheets with soil.

7) Consider visibility. Sheet mulches can be very apparent in high visibility areas. 

Measures to reduce unsightliness of sheet mulches include covering with aggregate 

mulches such as hay, straw, or wood mulch, or selecting sheet mulch colors that blend 

into the area.

Organic Aggregate Mulch – Organic aggregates are another group of materials that, when 

placed thickly around installed plants, will control the establishment of competing vegetation 

and reduce surface evaporation (Figure 10.17). These aggregates include hay, straw, or chipped 

and shredded wood materials. Organic aggregates are often used in highly visible areas because 

they are more esthetic in appearance than sheet mulches. They are also used in planting islands 

for long-term control of competing vegetation.

The eff ectiveness of organic aggregate mulches on seedling survival and growth depends on 

the depth, total area covered, the control of seed germination of competing vegetation, and 

its longevity.

The longevity of organic aggregate mulches is a function of: 1) C:N, 2) texture, and 3) depth. 

High C:N materials, such as uncomposted, shredded wood, bark, or sawdust, will last longer 

than low C:N materials, such as composted yard materials, because these materials are in the 

initial stages of the decomposition cycle. Coarse-textured materials (Figure 10.18) have greater 

longevity than fi ner-textured materials because coarser materials have less surface area for 

microbial break down (Slick and Curtis 1985). Coarse-textured materials also tend to hold less 

moisture, which slows decomposition rates. The longevity of an organic aggregate mulch also 

depends on the application thickness – the thicker the layer of mulch, the longer it will last.

The same factors that aff ect longevity (e.g., texture, C:N, depth) also determine the eff ectiveness 

of aggregate mulches in deterring seed germination of unwanted vegetation around the 

seedling. Coarse-textured mulches are excellent mulches because they hold very little moisture 

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Figure 10.17 – This photograph was taken 

in late summer, months after adjacent 

soils had dried out. The lack of competing 

vegetation and the low surface evaporation 

resulting from the placement of 3 to 4 inches 

of coarse sawdust resulted in very high soil 

moisture. The high C:N of the sawdust was 

believed to be a factor in inhibiting the 

establishment of weedy annuals.

204
at the mulch surface, and are therefore poor environments for seed germination of unwanted 

vegetation. Fine-textured mulches, on the other hand, create a more favorable environment 

for seed germination because they hold more moisture and are in closer contact with seeds. 

For this reason, many fi ne-textured materials, such as composts, are actually excellent growing 

media for weed seed germination and establishment. As discussed in Section 5.8.1.2, mulch 

materials with high C:N discourage growth of weedy annuals because high C:N materials 

remove available nitrogen that would otherwise give these species a competitive advantage. 

The eff ectiveness of a mulch in discouraging the establishment of competing vegetation 

generally increases with the thickness it is placed on the soil surface (Baskin and Baskin 1989). 

The most eff ective mulch thicknesses are between 3 to 4 inches (Pellett and Heleba 1995; 

Ozores-Hampton 1998), but thicknesses as low as 1.5 inches have been found to be eff ective for 

some small-seeded weed species that need sunlight for germination (Penny and Neal 2003). 

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0” 1” 2” 3” 0” 1” 2” 3”

0” 1” 2” 3” 0” 1” 2” 3”

0” 1” 2” 3” 0” 1” 2” 3”

A B

C D

E F

Figure 10.18 – Examples of diff erent types and textures of mulches: ( A) freshly ground coarse 

wood passing a 3 inch screen; (B) freshly ground coarse wood passing a 1.5 inch screen; (C) 

freshly chipped wood; (D) composted mixtures of ground wood, biosolids, and yard wastes 

passing a 1.5 inch screen; (E) weathered straw; (F) ponderosa pine needles.

205
Organic aggregate mulches have several advantages over sheet mulches. First, organic mulches 

can be applied over a much larger area than sheet mulches. Some projects have organic 

mulches covering the entire site, while other projects concentrate it in strategic areas, such 

as planting islands. Second, organic aggregate mulches moderate surface soil temperatures, 

whereas sheet mulches can actually increase surface temperatures. Mulch thicknesses of 

3 inches have been found to reduce soil temperatures below mulch layers by 8 to 10 °F (Slick 

and Curtis 1985; Steinfeld 2004), which can benefi t the growth of seedlings on very hot sites. 

The insulative quality of mulches also aff ects the seasonal heating and cooling patterns in the 

soil. Soils under thick mulches take longer to warm in the spring, but in the fall, take longer to 

cool down. Depending on the temperature and rainfall patterns of a site, this could infl uence 

seedling establishment.

Mulch can create problems to planted seedlings if it is placed in contact with the plant stem. The 

high moisture around the stem can be conducive to pathogenic injury. On southern exposures, 

heat will build up at the surface of, and directly above, the mulch, creating extremely high 

temperatures on warm summer days. The high temperatures can cause heat damage to stems 

of young seedlings. It is important, therefore, to keep mulch several inches away from the stem 

of planted seedlings. 

10.1.3.4 Soil Improvement

Mulches are sometimes used specifi cally to increase the nutrient and organic matter status 

of a soil. Composted organic materials are used for these purposes and are characterized by 

having low C:N, high nutrient levels, fi ne textures, and dark colors. While these materials are 

typically more eff ective when incorporated into the soil, they are sometimes applied to the 

surface of the soil where tillage is not feasible (steep and rocky) or tillage costs are unaff ordable. 

Where composted organic materials are applied on the soil surface, the nutrient release rates 

will be much slower. See Section 10.1.5, Organic Matter Amendments, for more information 

on composts.

10.1.3.5 Seed Supply 

The objectives for applying mulch on some projects are to spread materials that contain native 

seeds. There are several mulch materials that carry native seeds, including duff , litter, and straw 

from native seed production fi elds. When these materials are applied to the soil surface, seeds 

will germinate given favorable environmental conditions. 

Duff and Litter – Duff and litter layers are organic mats that form under tree and shrub 

plant communities. These layers are accumulations of years of leaves and needles at varying 

degrees of decomposition. Included in these layers are dormant seeds, many of which are 

still viable. When the duff , litter, and seed bank is collected and spread on disturbed sites the 

environmental conditions for breaking seed dormancy of some species may be met and seeds 

will germinate. 

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Figure 10.19 – Large mulching operations require access and working space. The operation 

shown in this photograph shows the wood waste material being dropped into a grinder with 

an excavator (left), and conveyed as mulch to the bucket of a front end loader (right).

206
Duff and litter can be collected from adjacent forest- or shrub-dominated sites or salvaged 

prior to construction. Reapplying them to disturbed sites completes several operations at 

once: 1) adds seeds, 2) covers seeds, and 3) adds a supply of long-term nutrients. Although this 

practice might seem expensive or impractical, when compared with purchasing and applying 

seeds, fertilizer, and mulch separately, the costs might be comparable. See Section 10.1.3.11 for 

more information on litter and duff .

Native Hay From Seed Production Fields – One of the byproducts of native grass seed 

production is the stubble that remains in the fi elds after seed harvest. This stubble contains 

varying quantities of unharvested seeds, which eventually end up in bales. If bales are stored 

in dry conditions, seeds can remain viable for several years. When hay bales containing the 

native seeds are spread as a mulch on disturbed sites, seeds come into contact with soil and 

eventually germinate. See Section 10.1.3.9 for more information on straw and hay.

10.1.3.6 Selecting the Appropriate Mulch Materials

There are a variety of materials that can be used as mulches:

 · Wood fi ber,

 · Erosion mats,

 · Hay and straw,

 · Manufactured wood strands,

· Duff and Litter,

 · Composts (See Section 10.1.5), and

 · Hydromulch (See Section 10.3.2).

The following sections describe these materials and how they are used in revegetation projects. 

Figure 10.18 gives examples of some of these mulches.

10.1.3.7 Wood Fiber

Mulches produced from woody materials are used primarily for seed covering and seedling 

mulching. There is usually a readily-available source of wood material from project sites situated 

in forested environments. Branches, stems, bark, and root wads are typical waste products from 

clearing and grubbing that can be chipped or mulched on site to produce various types of wood 

mulch. In the past, this material has been burned or hauled to waste areas for disposal. With 

greater burning restrictions and higher hauling costs, chipping these materials and returning 

them to disturbed sites as mulch are practices that are becoming more common. 

Wood Fiber Mulch Production – Creating mulch from right-of-way clearing woody material 

requires planning and coordination. First the road contractor piles the woody right-of-way 

clearing debris into “slash piles.” These piles include tree boles, bark, branches, and stumps, 

but must not contain large rocks or other inert materials that can cause wear or damage to the 

equipment. When clearing and piling is completed, a company that specializes in processing 

wood waste is contracted (typically by the road contractor). In this operation, equipment is 

brought to each slash pile and materials in these piles are processed into mulch. The resulting 

wood mulch is either placed in piles adjacent to the slash piles or transported to designated 

storage sites. The timing of these operations should consider the possibility of limited 

equipment use due to fi re restrictions, which typically occurs in the western United States from 

mid summer through early fall.

If undesirable plant species are included in the slash piles, spread of these species is likely to 

occur when they are processed and applied as a mulch. This can be prevented by identifying 

these plant populations on site during the weed assessment (See Section 5.8.2.1) and avoiding 

placing them into slash piles.

It is important to defi ne the desired mulch characteristics prior to processing the piles. This can 

be diffi cult since there are a variety of wood waste reduction equipment, producing diff erent 

dimensions and fi brosity (the degree that wood fi bers are separated). Specifying the particle size 

and shape by stating a screen size the material must pass does not always produce the desired 

material. Screens only sort for two dimensions, and not for length or fi brousness. Identifying 

the type of waste reduction equipment can narrow the type of mulch produced (Table 10.5). 

For example, mulch produced by shredders is long and fi brous (Figure 10.18 A and B), whereas 

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mulch produced from chippers has close to equal length sides, with fi bers still intact (Figure 

10.18 C). Visiting with mulch company representatives and viewing the type of products they 

produce is a good way to determine the types of products you can expect to receive. If this is 

not possible, have them send you samples of diff erent mulch products. Typically, the coarser 

the size of the mulch, the cheaper will be production costs since more mulch of coarser size 

can be produced in a given time frame than smaller textured mulch. Other factors, such as tree 

species, moisture content, and portion of tree processed, will aff ect the characteristics of the 

mulch. If the wood is wet during processing, it is more likely to be shredded; if it is dry, it will 

be more chip-like. There is also variation in mulches based on species of origin. For example, 

ponderosa pine (Pinus ponderosa) and western juniper (Juniperus occidentalis) tend to create 

more fi brous mulch than lodgepole pine (Pinus contorta). Processed root wads tend to be more 

fi brous than boles of trees. 

Purchasing Wood Fiber Mulches – On projects where waste materials are not available for 

mulching, the purchase of wood fi ber mulches should be considered. Overall costs are much 

higher because of the added expenses of transporting these materials to the site. If commercial 

mulch sources are nearby, this can be an economically viable option. It is very important to be 

sure of the quality of the material. Testing methods and specifi cations can be developed that 

are similar to those given in Section 10.1.5.

Applying Wood Fiber Mulch – Wood fi ber mulch is typically applied with mulch-blowing 

equipment. This equipment has varying transport capacities, ranging from 25 to 100 yards of 

material (Figure 10.20). An application hose is positioned where mulch is to be applied and is 

pneumatically delivered from the mulch bins to the site. The amount of mulch applied depends 

on the objective. For seeding, application rates range from 100 yd3/ac (0.75-inch thickness) 

to 135 yd3/ac (1.0-inch thickness). For seedlings, mulch application ranges from 400 yd3/ac 

(3 inch-thickness) to 540 yd3/ac (4-inch thickness). Note: The higher rates used for mulching 

seedlings are only used in close proximity to the plants. The remaining areas are mulched at a 

lower rate. 

Application rates depend on factors such as length and diameter of hose, blowing equipment, 

elevation rise, and dimension of the area being covered. Rates of application typically range 

from 25 to 35 yd3/hr. If mulch is applied at a 1-inch depth (134 yd3/ac), it would take between 

4 to 5 hours to cover an acre. These are optimum rates because they do not account for the time 

it takes to travel to the mulch source, load the mulch bin, and travel back to the application site. 

The time required to make these trips can sometimes be longer than the actual application of 

the mulch. Using larger transport capacities is one way to signifi cantly cut the time associated 

with refi lling mulch bins. 

Mulch blowing equipment can be used on any slope gradient that can be accessed by foot. 

By using ropes, slope gradients of up 1H:1V can be accessed. Hose lengths can be attached to 

extend the delivery of mulch up to 400 ft. Since mulch is delivered through hoses, the system 

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Table 10.5 – Table of general types of wood waste reduction equipment (modifi ed from ReSourcing Associates and CPM Consultants 1997).

General 

Equipment 

Types

Examples Feedstock Particle Geometry

Chippers Disc Chippers, Drum 

Chippers

whole logs, clean 

residuals

clean edge, two-sided

Hogs Swing Hammer, Fixed 

Hammer, Punch & 

Die, Mass Rotor

wood waste, stumps, 

land clearing debris

coarse, multi-surfaced, 

fi brous

Shredders Low Speed-High 

Torque, High Speed

wood waste, stumps, 

land clearing debris

coarse, multi-surfaced, 

fi brous

Hybrids Knife Hogs, Pan & 

Disc

wood waste, stumps, 

land clearing debris

semi-coarse

208
will plug if the size of the wood fi bers exceeds the tube size. It is therefore important that 

mulch be free of large pieces of wood. Using a mulch blower is an excellent method for evenly 

applying wood fi ber, but frequent monitoring by inspectors is important to assure that the 

specifi ed amount of mulch is being applied. 

Where slopes gradients are gentle and free of rock and debris, wood fi ber mulch can be evenly 

applied with a manure spreader. Mulch can also be moved to the site in tractor buckets and 

spread across the soil surface with the blade or bucket of the tractor. Obtaining an even mulch 

depth is extremely diffi cult using this method, and requires many passes of the equipment that 

invariably compacts the soil. An alternative is to deliver several yards of mulch to a planting 

island in the bucket or shovel of a tractor or excavator. After the seedlings are planted, mulch 

can be hand raked at the specifi ed thickness to cover the island.

Mulch Storage – If wood fi ber is stored for long periods of time, the materials should not be 

placed in piles taller than 10 ft. Fresh piles of wood fi ber have the potential to spontaneously 

ignite in larger piles, creating a fi re hazard and potential loss of material. Consider placing a 

plastic covering over the piles to keep moisture out during the winter because wet mulch is 

harder to apply through a mulch blower than drier mulch. 

Seed Placement During Mulching – Seeds can be sown prior to or during mulch operation. 

Sowing that is done before mulching can be accomplished through dryland sowing methods 

or through hydroseeding. Applying seeds during the mulching operation is accomplished 

by placing seeds in a “seed metering bin” attached to most mulch-blowing equipment. This 

equipment meters seeds into the mulch as it is being applied. The rate at which the metering 

system delivers seeds can be adjusted and must be calibrated prior to mulching to obtain the 

desired seed density (See Section 10.3.1, Seeding, for seed calibration methods). Recalibration 

should be done when seed rates or mulching rates have been changed. 

Fertilizers – It is diffi cult to evenly apply fertilizers through a mulch blower system. Outside of 

mixing fertilizers in the mulch prior to placing it into the mulch bins, fertilizing must be done in a 

separate operation, either before or after mulching. Applying fertilizer through a hydroseeding 

system after seedling establishment is one strategy for increasing available nutrients on the 

site. As discussed in Section 10.1.1, Fertilizers, the delayed timing of fertilization reduces the 

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A B

C

Figure 10.20 – Wood fi ber mulch is applied on steeper slopes with mulch blowing equipment. 

Large trucks can hold between 75 and 100 yards of mulch (A) while smaller trucks can hold up 

to 25 yards (C). Mulch is pneumatically delivered to the site through an application hose which 

can reach several hundred feet up steep slopes (A) with still enough force for ample delivery of 

mulch (B).

209
risk of nutrient leaching and increases the 

probability that nutrients will be available at 

the levels needed for established plants. 

10.1.3.8 Erosion Mats

Erosion mats are manufactured blankets or 

mats designed to increase surface stability 

and control erosion. They are available in 

strips or rolls with a minimum thickness 

of 0.75 inch. Erosion control revegetative 

mats (ECRM) or rolled erosion controlled 

products (RECP) are applied directly to the 

soil surface for control of sheet erosion and 

to aid the establishment of vegetation. Turf 

reinforcement mats (TRM) are materials that 

are fi lled with soil when installed to increase 

surface soil strength (Kemp 2006). 

There are a multitude of products on 

the market, with a range in design and 

costs. Figuring out which products will 

serve your project needs at the right 

price can be challenging. Several state 

departments of transportation periodically 

evaluate and compare the shear stress, soil 

erosion protection, longevity, and other 

characteristics for these products (Caltrans 

2003; Kemp 2006) and these documents 

are usually available on the internet. Since 

the installed costs of erosion mats can be 

very expensive, it is important that the job 

is done right. Taking the time to select the appropriate erosion mats, native species mix, and 

seed placement techniques is essential for assuring that revegetation is successful. Small fi eld 

trials using diff erent species and erosion mats can help in these decisions (Figure 10.21).

The same characteristics that create an optimum environment for seed germination in 

other mulches are also important to consider when selecting erosion mats. Typically, those 

materials that protect the seeds from drying out but allow light and space for germinating 

seeds to grow into seedlings will perform the best for revegetation establishment. The thicker 

erosion mats with the most loft should have better conditions for seedling establishment than 

thinner materials. 

The drawbacks to erosion mats are generally not in the product itself, but in how it gets applied 

to the site. Poorly applied erosion mats can result in sheet and rill erosion under the fabric. To 

avoid this problem, several important measures should be taken when installing erosion mats. 

First, the surface of the soil must be smoothed to a uniform elevation before the mat is placed. 

This will assure that when the mat is pinned to the soil, it is in intimate contact with the soil 

surface. Second, the materials must be trenched or keyed into the soil at the upper reaches of 

the fabric. This will assure that the material does not move downslope. Third, as with all slopes 

being revegetated, concentrated water should be kept off these slopes.

Seeds must be sown on the site prior to installing erosion mats. This can be done using any type 

of seeding method (e.g., hydroseed, drill, or hand broadcast). Care must be taken during and 

after mat installation to avoid disruption to the seedbed. Unless the seeds are extremely small, 

sowing seeds over installed erosion mats is not recommended because larger seeds will hang 

up in the fabric. Small seeds can be applied over erosion mats if tackifi ers are not used and if the 

timing is correct so suffi cient rain will move it through the erosion mat to the soil surface.

Some manufacturers off er erosion mats that are impregnated with seeds, eliminating the need 

for sowing. This method is advantageous on steep slopes or soil-faced gabion walls (Inset 10.3) 

where placing seed prior to mat installation is very diffi cult. It is important to work directly 

with companies that provide these products by supplying them with source specifi c seeds and 

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Figure 10.21 – Small fi eld trials can help 

select the most appropriate species and 

materials for a project. The trial shown in 

this picture compared straw mat (A and 

B) with a polywoven mat (C and D). It also 

compared the growth of blue wild rye 

(Elymus glaucus) and California fescue 

(Festuca californica) (A and C). The fi rst 

year results indicated that there was much 

better establishment of grasses on the 

polywoven erosion mat than the straw 

mat, yet no diff erence in species growth. 

Maintaining the trial for two years showed 

that California fescue outperformed blue 

wild rye. These results led to using California 

fescue and polywoven erosion mat for the 

project described in Inset 10.3.

A B C D

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specifying appropriate sowing rates. For successful germination, seeded erosion mats must be 

installed so that the seeds and fabric are in direct contact with the soil. 

10.1.3.9 Straw and Hay

Straw and hay are long-fi bered mulches used on many revegetation projects for seed cover 

and erosion control (Figure 10.18E). The terms straw and hay are often used interchangeably. 

However, straw is the stubble left over after seeds have been harvested from commercial 

seed or grain crops; hay comes from grass/legume fi elds usually grown for feed. When hay is 

harvested, it usually contains seeds from a variety of pasture species. 

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Compost

Amended

Soil

Wire Mesh

Frame

A B C

D E

Inset 10.3 – Case Study: Erosion Mats with Native Grasses and Forbs

Reconstruction of the Agness-Illahe Highway required the construction of long sections 

of gabion walls. Since this highway is visible from the Rogue River (a designated “wild and 

scenic” river in southwestern Oregon) and is heavily traveled for recreational purposes, 

it was important that the gabion walls be visually screened using native plants. Gabions 

were designed to hold 12 inches of compost-amended soil (topsoil was not available) on 

the face of the walls by wire mesh frames (Figure A). Placement of seeds at the surface of 

the gabion wall was problematic. Several small plots using diff erent erosion mats, seed 

mixes, seed rates and seed-attaching methods were tested to determine how to best meet 

the revegetation objectives (Figure 10.21). 

The results from these trials indicated that we could attach native grass and forb seeds 

to erosion mats using a tackifi er (B). In 2003, we applied our fi ndings to the construction 

project. Needing approximately 33,000 ft2 of gabion wall facing, we prepared the erosion 

mats by rolling them out on a road surface, applying California fescue (Festuca californica), 

gluing the seeds to the mat, and re-rolling the erosion mats. 

The seeds held tightly to the fabric during transportation and handling. At the construction 

site, seeded mats were attached to the wire mesh at the face of the wall (C) and compostamended soil was placed behind the screen and lightly tamped. The gabion walls were 

built in the summer of 2003, but the seeds did not germinate until late fall after several 

rainstorms. Figure D shows a close up section of wall with newly germinating seedlings 

coming through the erosion mat in late 2003, four months after wall construction. Figure 

E shows 20 to 30 ft high walls in July 2006, three years later, fully vegetated and eff ectively 

screening the walls from the road and river (Photo C courtesy of Scott Blower).

211
Straw and hay are often used on revegetation projects because they are available, 

comparatively inexpensive, and generally successful in establishing grass and forb plants from 

seeds. The long stems of these materials create loft, or high porosity, that keeps moisture near 

the soil surface where seeds are germinating. This creates a favorable environment for young 

seedlings by allowing sunlight to penetrate and protecting the young seedlings during the 

early stages of establishment.

Straw is often preferred over hay because it generally contains fewer undesirable seeds. The 

seeds that are contained in the straw may not always be considered inappropriate for use in 

revegetation projects. For example, straw from some grain production fi elds (e.g., rice straw) 

has seeds of species that are not adapted to wildland environments and therefore will not 

become established. Straw produced from native seed production fi elds, on the other hand, is 

desirable if the fi elds are grown from identifi ed genetic sources and used for projects within the 

seed transfer zones. Not only does source-identifi ed straw act as a mulch, but it also supplies 

extra native seeds to the site. Some native grass species grown for seed production are very 

diffi cult to harvest and clean. For these species, the seeds are not harvested, but baled together 

with the grass stems. The seeded bales are applied directly to the site through straw blowing 

equipment, accomplishing seeding and mulching in one operation (Figures 10.22 and 10.23). 

This method off ers a practical alternative to species such as bottlebrush squirreltail (Elymus 

elymoides) or western needlegrass (Achnatherum occidentale) which can be diffi cult to harvest 

and clean. 

Purchasing Straw and Hay – The drawbacks to using straw and hay are that these materials 

can contain seeds from undesirable species, are susceptible to wind movement, have limited 

application distance, and decompose in a relatively short time compared to other mulches. 

Introducing seeds of undesirable species from straw and hay sources is an important 

consideration when choosing a source. There are many examples where, in the urgency of 

erosion control, straw or hay from unknown sources was applied, resulting in the introduction 

of weed species. The assumption in most of these cases was that short-term control of soil 

erosion and sediment production outweighed the long-term introduction of undesirable 

plant species. The potential disastrous results from these assumptions need to be understood 

and agreed upon prior to applying hay or straw from unknown sources. Good integration of 

erosion control and revegetation planning can eliminate the need for last minute purchase and 

application of unknown or undesirable hay or straw sources.

A good source of straw is native seed production fi elds. Seed growers identify straw bales by 

genetic source, so it is important to be sure that the source-identifi ed bales are appropriate for 

the geographic area of the project site. Because of the potential for introducing weeds to your 

project site, you must be very certain of the species present in the hay or straw you are applying 

to your site. Many states have certifi cation programs that inspect fi elds and certify that the 

bales are “weed free.” Be clear what “weed free” means when you purchase these materials. 

There can be other seeds in the bales that, while not considered weeds by the certifying state, 

might nevertheless be unwanted on your site. A conservative approach for non-certifi ed seeds 

is to examine the fi elds that will be producing your bales and observe which species are present 

before they are harvested. It must be assumed that if a species of grass or forb is present in a 

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Figure 10.22 – Seeds of some species are baled with straw because of the diffi culty of seed 

harvesting and cleaning. The long awns of the squirreltail seeds (A) show how diffi cult collecting 

and handling these seeds can be. The squirreltail seeds are germinating from the heads of the 

seeds that came in the bales (B).

212
hay fi eld, seeds from these plants will show 

up in the bales. 

Some species grown for native seed 

production are diffi cult to harvest and 

clean because of long awns (Figure 10.22). 

An alternative method of seed harvest for 

these species is to allow the seeds to ripen 

in the fi elds and bale the seeds and grass 

stems together. The seed bales are applied 

to the site through hay blowing equipment. 

The seeds are detached from the stem as it 

is blown through the equipment, falling 

to the surface of the soil and covered by 

the grass stems. This is an eff ective means 

of applying seeds and seed covering in 

one operation.

Some things to require when purchasing 

straw or hay are: 

 · Source must meet or exceed State 

Certification Standards for “weed 

free.” Many states have straw certifi cation programs. Where no standards programs 

exist, acceptance should be based on seed crop inspection reports and/or visual fi eld 

inspections by the COTR prior to harvest. Standards may also be set by the Government 

and listed on individual task orders.

 · Straw or hay must be baled and secured according to specifi cations listed on the Task 

Order. Generally, bales should be less than 100 lbs.

 · Bales should not be allowed to become wet after harvest or during storage prior 

to delivery.

The quality of straw and hay varies between grass species. Rice straw, for instance, is wiry and 

does not readily shatter, which makes it more diffi cult to apply as compared to wheat, barley, 

or oats (Kay 1983; Jackson and others 1988). Native straw is generally longer and stronger than 

grain straw (Norland 2000). Yet within native grasses, some species have better properties as 

mulches than others. Larger stemmed grasses, such as blue wildrye (Elymus glaucus), mountain 

brome (Bromus marginatus), and bluebunch wheatgrass (Pseudoroegneria spicata) make good 

mulches because of the large leaves and stems.

Application – Straw and hay can be spread by hand or with a straw blower. For large jobs, 

using a straw blower is the most practical application method. There are many types of straw 

blowers available on the market, ranging from very small systems (Figure 10.23) that deliver 

from 30 to 180 bales per hour to large straw blowers that operate at rates up to 20 tons per 

hour. The distance that straw or hay can be blown depends on the hay blowing equipment, 

wind conditions during application, straw characteristics, and whether the material is being 

applied upslope or downslope (cuts or fi lls). When wind is favorable, straw can be shot up 

to 100 ft. However, when wind is blowing against the direction mulch is being applied, the 

distance is reduced. Because of the limited application range, this equipment is limited to sites 

adjacent to roads. The upper portions of steep, extensive slopes are typically not reachable by 

straw blowers. 

When straw is used as a seed mulch, it is important that the application rates are not too deep 

that a physical barrier is formed. A minimum depth that has been shown to control evaporation 

is one inch (Slick and Curtis 1985). Applying too much straw will restrict sunlight and growing 

space for establishing seedlings. A rule of thumb is that some surface soil (15% to 20%) should 

be visible through the straw after application (Kay 1972, 1983; Jackson and others 1988). This 

equates to 1.5 to 2 tons per acre, depending on the type of straw and its moisture content.

Straw is susceptible to movement with moderate to high winds. Tackifi ers are often applied over 

the straw to keep it in place (Kay 1978). Products such as guar and plantago are used with low 

quantities of hydromulch to bind straw together (Manufacturers have stated application rates 

for this purpose).Straw can also be crimped, rolled, or punched into the soil. These measures 

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Figure 10.23 – Straw blowers range in size 

from machines which can apply 30 to 60 bales 

per hour (shown here) to very large straw 

blowers that can shoot up to 20 tons 

per hour.

213
will stabilize the straw by burying portions of the stems into the soil and can increase erosion 

protection because of the more intimate contact of straw with the soil surface. The potential for 

compaction is increased with these treatments and the tradeoff s of off setting surface stability 

with long-term soil productivity should be weighed.

10.1.3.10 Wood Strands

Wood strands are long, thin pieces of wood, produced from wood waste veneer. This product 

was developed as an eff ective erosion control alternative to straw and hay (Foltz and Dooley 

2003). The advantages of wood strands over straw are that it is free of seeds, has a longer life, 

and is more resistant to wind. 

Wood strands, like straw, form a stable cover with high porosity or loft, characteristics which are 

important for controlling soil moisture and temperature around the germinating seeds. The 

large spaces or pores created by the wood strands allow space, light, and protection for young 

emerging seedlings (Figure 10.13). Unlike straw, these materials keep their structure or porosity 

over time, and do not compress with snow or lose fi ber strength through decomposition. 

While the performance of this new product as a seed cover has not been tested, it has all the 

characteristics of being an excellent seed cover. The application rates for wood strands are 

likely to follow the guides for straw – at least 15% to 20% of the soil surface should be visible. 

This is likely to be greater than the recommended rates for erosion control. Installing small test 

plots of varying thicknesses of mulch would be a good means to determine the appropriate 

thickness for optimum seed germination. Wood strands are delivered in diff erent size bales and 

applied by hand or through straw blowing equipment (Figure 10.23). As with straw, this product 

is limited by the accessibility of the site by hay transportation and blowing equipment. 

10.1.3.11 Litter and Duff

Litter is the layer of fresh and partially decomposed needles and leaves that cover the surface 

of most forest and shrub plant community soils. Duff is the dark, decomposed layer directly 

below the litter layer (leaves and needles are not identifi able in the duff layer) that is high in 

nutrients and humus. In addition to providing soil protection and nutrients, litter and duff can 

also contain dormant, yet viable, seeds from species that make up the forest or shrub plant 

communities. When litter and duff are collected, they should be matched to the appropriate 

revegetation site. For example, litter and duff collected from cool, moist sites should not be 

applied on hot, dry sites.

The depth that litter and duff accumulates will vary by species composition, age, and productivity 

of the plant community. Dense stands of ponderosa pine can produce thick layers of litter. 

More open forest stands on dry, less productive sites will have thinner layers of duff and litter 

(often less than an inch deep). The quality of the litter for erosion control and longevity varies 

by the dominant forest or shrub species. Pine needles provide the greatest benefi t because the 

long needles interlock, reducing the potential of movement from rain or wind erosion (Figure 

10.18F). Needles from species such as Douglas-fi r are shorter and tend to compact, providing 

less surface stability. Litter from shrub plant communities provides less protection because the 

leaves are less interlocking. Nevertheless, these materials should not be overlooked because 

they can be a source for seeds and nutrients.

The collection of litter in the western states has typically been done manually by raking. 

Mechanizing the collection of litter has been done in the southern United States. The pine straw 

industry is well developed in this part of the country. Baling equipment has been developed for 

this industry and might be applicable to the western United States. Collection of needles and 

duff should be done during the summer and fall, when the litter and duff are completely dry. If 

these materials are not used immediately, they should be placed in small piles and completely 

covered by plastic to keep the materials dry. Excessive moisture can turn the piles into compost 

and possibly aff ect seed viability.

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Inset 10.4 – Pine Straw Industry

Using forest litter as a mulch is not a new concept – pine needles have been a popular 

landscaping mulch in the southern United States for the past 25 years. The “pine straw” 

industry, as it is referred to, has been established to harvest needles in a sustainable manner 

from young plantations of southern pine species to meet this demand.

214
Litter and duff can be applied manually to disturbed sites. If viable seed rates are high in the 

litter and duff , and it does not contain large material, it can be applied in a variety of ways (e.g., 

hydroseeder, mulch blowing equipment).

One method for determining the amount of viable seeds in a litter layer is to actually conduct a 

germination test at the project site over a several year period by obtaining litter and duff from 

several potential collection areas and testing them on nearby sites. Like soil sampling, samples 

should be collected by obtaining a composite of subsamples of an area. Collect samples from 

each of the plant communities that are considered for litter collection and keep these samples 

separate. Establish test plots at sites that are representative of each revegetation unit (these 

can be reference sites). Each plot should be well marked (each corner identifi ed with stakes 

and permanent labels identifying the litter source) and located where it will not be disturbed. 

Plots must be free of vegetation and top several inches of soil should be removed to eliminate 

potential seed sources. A known amount of litter (either by dry weight or by volume) should be 

spread across each plot. Visit the plots during the spring and count the number of seeds that 

are germinating. During the summer or fall, identify plant species and count individual plants 

in the plots. At the end of the assessment, calculate the number of seedlings per known volume 

or weight of litter material. These fi gures can then be used to determine the rate of litter to 

be applied.

10.1.4 TOPSOIL

10.1.4.1 Introduction

Topsoiling is the salvage, storage, and application of topsoil material to provide a suitable 

growing medium for vegetation and to enhance soil infi ltration (Rauzi and Tresler 1978; 

Woodmansee and others 1978; NRCS 1994). Topsoiling has been found to increase plant cover 

and biomass through an increase in nutrient availability, water-holding capacity, and microbial 

activity, including mycorrhizae (Claassen and Zasoski 1994). It has also been found to increase 

the number of plant species native to the area. Bailey (2004) found that the application of 3 

inches of topsoil over subsoil in eastern Washington increased the presence of native species 

by a factor of four and increased vegetative ground cover the fi rst and second year by 20%. 

While topsoiling has many benefi cial eff ects for revegetation, topsoiling cannot recreate the 

original undisturbed soil. In the process of removing and reapplying topsoil, soils undergo a 

loss of 1) soil aggregation, 2) organic nitrogen, 3) arbuscular mycorrhizal fungi (AMF) inoculum, 

and 4) microbial biomass carbon (Visser and others 1984). Minimizing topsoil disturbance is 

preferred to topsoiling, especially on sensitive soils, such as those derived from granitic and 

serpentine bedrock (Claassen and others 1995).

10.1.4.2 Salvaging Topsoil

The removal of topsoil should only be done in areas that will be excavated, severely compacted, 

or buried with excavated material, such as fi ll slopes. These areas are usually identifi ed early in 

the planning stages. During the assessment phase of the revegetation plan, a topsoil survey 

should be conducted to determine the depth and quality of the topsoil that will be excavated 

(See Section 5.5.1). Ideally, only the topsoil is removed in the excavation process. Mixing topsoil 

and subsoil together will dilute microbial biomass and mycorrhizal inoculum of the topsoil, 

which will decrease their eff ectiveness in reestablishing nutrient cycling.

Topsoil quality should be determined from laboratory tests and fi eld surveys. Topsoils with 

high sodium, high salinity, very high or very low pH, or any other condition that may be toxic 

to plant growth should be avoided (Rauzi and Tresler 1978). If weeds are observed during the 

fi eld survey, it should be assumed that the seeds of these species are present in the topsoil 

and these areas should be avoided. During topsoil excavation, the litter and duff layers are 

usually removed with the topsoil. These layers are sources of decomposed and partially 

decomposed organic matter. Under topsoil storage conditions, this material will undergo 

some decomposition, releasing nutrients. Separation of duff and litter from the topsoil prior 

to topsoil excavation should be considered when the duff and litter are to be used as a native 

seed source or soil cover. 

It is best to excavate topsoil when soils are relatively dry. Under dry conditions, there is less 

potential to compact the soil or destroy soil aggregation. Dry topsoil should also store longer 

and maintain better viability than moist topsoil (Visser, Fujikawa, and others 1984). The period 

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when topsoils are dry is generally limited to the beginning of the summer through the middle of 

fall, which may not always lend itself to construction schedules. Restricting topsoil excavation 

operations to dry periods should be considered for large topsoil piles or if topsoil will remain in 

piles for greater than one year.

Topsoil layers are typically removed with either the blade of a tractor or excavator bucket. Soil 

compaction should be minimized prior to removal, which requires keeping large equipment 

travel to a minimum. Topsoil is typically placed into berms at the bottom of fi ll slopes or top 

of cut slopes and stored there until it is reapplied. If salvaged in this manner, small piles are 

created and soil is minimally handled. Minimum berm dimensions are approximately 6 ft wide 

by 3 ft high, which is often not large enough for the amount of topsoil that needs to be stored. 

When this is the case, topsoil is trucked off site to larger storage piles. Because of the potential 

for weed invasion, potential off site topsoil storage areas should have a weed assessment 

conducted prior to selection of the site.

10.1.4.3 Storing Topsoil 

The question often raised around storing topsoil is how long it can remain piled before it loses 

its viability. Studies have shown that stored topsoil can remain viable from 6 months (Claassen 

and Zasoski 1994) to several years (Miller and May 1979; Visser, Fujikawa, and others 1984; Visser, 

Griffi ths, and others 1984,) but will decrease in viability after 5 years (Miller and May 1979; Ross 

and Cairns 1981).

Viability of stored topsoil is a function of moisture, temperature, oxygen, nitrogen, and time. 

Stockpiled topsoil has been compared to “diff use composting systems” (Visser, Fujikawa, and 

others 1984) because, under optimum conditions, organic material in the topsoil will compost. 

Decomposition of organic matter in stored topsoil will reduce microbial biomass essential for 

nitrogen cycling (Ross and Cairns 1981) and fi ne roots that store mycorrhizal inoculum (Miller 

and May 1979; Miller and Jastrow 1992). Optimum environments for decomposition include 

high moisture, warm temperatures, and available nutrients, all conditions present in most 

topsoil piles. Climates with lower moisture and temperatures can be more favorable to longterm storage. A study in Alberta, Canada, for instance, revealed that topsoil had very little 

respiration or organic decomposition after three years in a stockpile due to the infl uence of 

the cold, dry climate (Visser, Fujikawa, and others 1984). Dry topsoils store longer and maintain 

greater populations of viable mycorrhizal fungi (Miller and Jastrow 1992). If a topsoil pile is to 

be held over winter in areas of moderate to high rainfall, it should be kept dry by covering with 

plastic (which will also keep the piles protected from erosion and weed establishment).

The size of the pile can also aff ect the viability of the topsoil. The interior of large piles 

maintain higher temperatures and are usually anaerobic, which can be detrimental to soil 

microorganisms. Microbial biomass levels and mycorrhizal fungi have been found to be very 

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A 0.14 %

From soil test of post construction 

soils - reported in gr/l, ppm, mg/kg, ug/g 

divide by 10,000 for %

Total soil nitrogen (or

other nutrient of interest)

in salvaged topsoil

F 4.5 inches The minimum thickness of topsoil to apply 

to meet minimum thresholds of nitrogen

Minimum topsoil application:

E/D * 12 =

E 1,100 lbs/ac Determined from reference sites or 

minimum thresholds from literature

Minimum or threshold

N levels

D 2,911 lbs/ac ft Calculated amount of total nitrogen in 

1 acre feet of soil

Nitrogen for soil layer

(A * B * C * 270) =

C 70 %

100% minus the rock fragment content -

from estimates made from sieved soil

prior to sending to lab

Fine soil fraction

B 1.1 gr/cc

Unless known, use 1.5 for compacted

subsoils, 1.3 for undisturbed soils, 

0.9 for light soils such as pumice

Soil bulk density

Figure 10.24 – Soil testing of salvaged topsoil can be used to calculate the thickness to apply 

in order to meet minimum nitrogen levels.

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low in the bottom of large stockpiles (Ross and Cairns 1981; Miller and Jastrow 1992). Most 

projects limit topsoil piles to 3 to 6 ft in height. This is not always possible, especially when 

topsoil storage space is limited. Under these circumstances, the size of the topsoil pile can be 

quite large. To reduce the negative eff ects associated with very large piles, topsoils should 

be salvaged dry and kept dry during storage. Large piles should be stored for as short a 

time as possible.

Standard specifi cations often call for temporary seeding of topsoil piles. The benefi ts of this 

practice are erosion control and maintenance of mycorrhizae inoculum through the presence 

of live roots. This practice should be evaluated for each project to avoid the introduction of 

undesirable plant species in the seeding mix if non-native species are used. Alternatives to this 

practice include hydromulching without seeds or covering with plastic. 

10.1.4.4 Reapplying Topsoil

The depth of topsoil application is generally based on the amount of topsoil available and the 

desired productivity of the site after application. As a rule, the deeper topsoil is applied, the 

higher the site productivity will be. If the objective is to restore a site to its original productivity, 

the placement of topsoil should be at a depth equal to or greater than the topsoil horizon of 

undisturbed reference sites. Suffi cient topsoil quantities however, are rarely available in the 

quantities needed to restore disturbed sites to their original topsoil depths. This often leads 

to applying topsoil too thinly across a project site. There may be a minimum topsoil depth 

below which the application of topsoil is not eff ective. Research on a northern California road 

construction site (Claassen and Zasoski 1994) suggests that a depth of 4 to 8 inches was required 

for an eff ective use of topsoil. On sites where the subsoil is unfavorable for plant establishment 

(e.g., very high or low pH, high sodium, high salinity), minimum depths of greater than 12 inches 

of topsoil should be considered (Bradshaw and others 1982). 

Determining minimum topsoil application depths can be based on the minimum amount of 

nitrogen required to establish a self-maintaining plant community. A threshold of approximately 

700 kg/ha (625 lb/ac) of total nitrogen in the topsoil has been suggested for sustaining a selfmaintaining plant community in a temperate climate (Bradshaw and others 1982). Claassen 

and Hogan (1998) suggest higher rates, especially on granitic soils, of 1,100 lb/ac total nitrogen. 

Using total nitrogen levels from soil tests of topsoil, the application thickness of topsoil can be 

determined using the calculations presented in Figure 10.24. 

Once the desired topsoil depth has been established, it must be determined whether there is 

enough stored topsoil available to meet these standards. The quantity of cubic yards of topsoil 

required per acre can be determined based on the depth of topsoil from Figure 10.25. For 

example, if an average of 10 inches of topsoil is required on a project, approximately 1,350 yd3/

ac topsoil would be needed. If there is not enough topsoil to meet this depth, then less than full 

coverage of the site should be considered over reducing the desired thickness of the topsoil. 

Figure 10.25 – The 

quantity of topsoil to apply 

to achieve a specifi ed 

topsoil thickness can be 

estimated by fi nding the 

desired depth of topsoil. For 

example, a 10-inch depth 

of topsoil would require 

1,350 yd3 of topsoil.

1,600

1,500

1,400

1,300

1,200

1,100

1,000

900

800

700

600

500

400

300

200

100

0

0 1 2 3 4 5 6 7 8 9 10 11 12

Desired Topsoil Depth (inches)

Topsoil to Apply (Cu Yds/Ac)

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Where topsoil quantities are limiting, 

it is important to develop a strategy 

that addresses the location the topsoil 

will be spread and the depth at which 

it will be applied. The strategy might 

concentrate topsoil in areas such as 

planting islands, planting pockets, or 

in a mosaic pattern that blends with 

the natural vegetative community. The 

non-topsoiled areas could be treated 

with other mitigating measures, 

such as organic matter incorporation 

or mulching. 

10.1.4.5 Manufactured Topsoil

The term manufactured topsoil (also 

termed “engineered topsoil”) is used 

to defi ne a soil created to perform like, 

or develop into, topsoil. It is usually manufactured off site and transported to the area where it 

will be applied. Manufactured topsoil is used in gabion walls, crib walls, or other bioengineered 

structures. It can also be used in planting pockets and planting islands. 

Selecting the appropriate organic matter, soil texture, and soil amendments for manufactured 

topsoil will increase the success of the project. The basic components of a manufactured topsoil 

are the loam borrow, compost, and soil amendments (e.g., fertilizer or lime amendment).

Loam Borrow – Loam borrow is any material that is composed of mineral particles meeting a 

suitable texture class (Figure 10.26). Loam borrow should have low coarse fragment content, 

not restrict plant growth, and be weed-free. This material can come from many sources, such as 

subsoils, river sands, and terrace deposits. Loam borrow must be tested and meet the general 

specifi cations shown in Table 10.6. If the loam borrow comes from subsoils or parent material, 

it should be assumed that benefi cial soil microorganisms are not present and should be added 

when the soil is manufactured. 

Compost – The organic component of manufactured topsoil (See Section 10.1.5) is composted 

materials from of a variety of materials including yard waste materials (grass clippings, leaves, 

and ground wood of trees and shrubs), sawdust, and biosolids. The heat generated during 

composting eff ectively reduces pathogens, weeds, and insects that may be hazardous to 

humans and detrimental to reestablishing vegetation. Compost must be free of weed seeds 

and vegetative material that propagate weedy plants (e.g., blackberry canes). The material 

must be well-composted, or stable, which can be indirectly determined by a respirometry 

test or calculated using C:N obtained from laboratory testing of nitrogen and organic matter. 

A stable compost will have a low respirometry rate (<8 mg CO2-C per g organic matter per day) 

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Figure 10.26 – Soil textures that are suitable as 

“loam borrow” are shown in light brown on the 

USDA textural triangle. 

SANDY

CLAY

CLAY LOAM

SANDY CLAY

LOAM

SILTY CLAY

LOAM

SILT

SILTY

CLAY

CLAY

90 10

80 20

70 30

60 40

50 50

40 60

30 70

20 80

10 90

90 80 70 60 50 40 30 20 10

LOAM SILTY

SANDY LOAM

LOAM LOAMY

 SAND SAND

100% 0%

0%

0% 100%

100%

Test Parameters Test Methods Loam Borrow

Physical Contaminates

(man-made inerts)

Man-made inert removal and classification

(TMECC 03.08-C)

Arsenic, Cadmium, Copper, Mercury, Manganese,

Molybdenum, Nickel, Lead (TMECC 04.06)

1:5 slurry pH (TMECC 04.11-A)

Electrical conductivity using

1:5 Slurry Method (dS/m)

% seedling emergence and relative

seedling vigor (TMECC 05.05-A)

(TMECC 05.02-A)

<1%

Meets US EPA, 40 CFR

503 regulations

5.0 -7.5

<5

>80% of control

<25

Trace Contaminants

pH

Soluble Salts

Bioassay

C:N Ratio

Table 10.6 – General specifi cation ranges for loam borrow used in manufactured topsoil. 

These can be modifi ed depending on the soil characteristics of the compost and other soil 

amendments (modifi ed after Alexander 2003b; CCREF and USCC 2006).

218
and low C:N (<25:1). A bioassay test which compares the rate of seedling emergence and seeds 

sown in compost to seeds sown in a control growing medium would be useful. Table 10.7 lists 

specifi ed values for a series of tests that should be performed on composted materials used in 

manufactured topsoils. 

To assure the delivery of high quality organic materials, compost should be obtained from a 

facility that participates in the Seal of Testing Assurance (STA) program (discussed in Section 

10.1.5). These compost facilities will send the latest lab results of the material of interest. A 

listing of STA compost facilities can be found at http://www.compostingcouncil.org. If a STA 

composting facility is not close enough to the project, other sources will have to be considered 

and testing the compost will rest on you. This will involve sampling the compost piles and 

sending the samples to an STA lab (a listing can be found at the Composting Council’s website). 

It is important that the compost piles be visually inspected prior to purchase to assure that 

noxious weeds are not present on or near the composting facility.

The compost application rates range from 10 to 30% by volume of the loam borrow. Section 

10.1.5 discusses how to determine specifi c organic matter rates. 

Other Amendments – Soil amendments, such as fertilizers, lime, and benefi cial 

microorganisms, can be applied to the compost and loam borrow to bring the manufactured soil 

into acceptable ranges for pH, nutrients, and microbiological parameters. The type and amount 

of amendments to apply can be determined by conducting a lab analysis on a sample of the 

manufactured topsoil. The sample must be from a combination of loam borrow and compost 

at the expected mixing ratio. From the results of the soil analysis, a determination for the rates 

fertilizers (See Section 10.1.1), lime amendments (See Section 10.1.6), and benefi cial organisms 

(See Section 10.1.7) can be made. 

Large quantities of manufactured topsoil can be mixed in a staging area. Using the bucket 

of a front end loader, the compost and loam borrow can be measured out by volume. For 

instance, using a 5 yd3 bucket, manufactured topsoil with a ratio of 25% compost and 75% loam 

borrow would have one scoop of compost applied to 3 scoops of loam borrow to produce 20 

yd3 of material. Additional amendments, such as fertilizers or lime materials, would be applied 

based on calculations for a 20 yd3 pile. Once all the materials have been placed in the pile, it is 

thoroughly mixed using the front end loader. 

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Test Parameters Test Methods Composted Material

Physical Contaminates

(man-made inerts)

Man-made inert removal and classification

(TMECC 03.08-C)

Arsenic, Cadmium, Copper, Mercury, Manganese,

Molybdenum, Nickel, Lead (TMECC 04.06)

1:5 slurry pH (TMECC 04.11-A)

Electrical conductivity using

1:5 Slurry Method (dS/m)

% seedling emergence and relative

seedling vigor (TMECC 05.05-A)

% wet weight (TMECC 03.09-A)

% by dry weight, loss on ignition (TMECC 05.07A)

Respirometry. Carbon dioxide evolution rate -

mg CO2-C per g OM per day (TMECC 05.08B)

(TMECC 05.02-A)

<1%

Meets US EPA, 40 CFR

503 regulations

5.0 -8.5

<5

>80% of control

30 - 60

25 to 60%

<8

<25

% of compost by dry weight passing a

selected mesh size, dry weight

(TMECC 02.12-B)

* 3”(75 mm) 100%

* 1”(25 mm), 90 -100%

* 3/4”(19 mm), 65 -100%

* 1/4”(6.4 mm), 0 -75%

* Maximum particle length

 of 6”(152 mm)

Trace Contaminants

pH

Soluble Salts

Bioassay

% Moisture Content

Total Organic Matter

Stability

C:N Ratio

Particle Size

Table 10.7 – General specifi cation ranges for composted materials for manufactured topsoil. 

These are generalized specifi cations that can be broadened depending on the soil characteristics 

of the loam borrow and site conditions (modifi ed after Alexander 2003b; CCREF and USCC 2006).

219
Purchasing loam borrow, compost and topsoil requires a set of contract specifi cations that assure 

product quality. The specifi cations in Tables 10.6 and 10.7 were developed for the DOT by the 

Composting Council Research and Education Foundation (Alexander 1993b). The tests are based 

on Test Method for the Examination of Composting and Composts (TMECC) protocols. These 

are general quality guidelines and can be broadened or made more constraining depending on 

the specifi cs of the project. When considering purchasing these products from a manufacturer, 

it is important to request the latest lab analysis. An STA facility (See Inset 10.7 in Section 10.1.5) 

will have these reports available while others might not. It is important that these tests be run 

by STA laboratories. It is also good to visit the location of the loam borrow, compost, or topsoil 

sources to determine whether there are undesirable or noxious weeds on or nearby the piles. If 

undesirable or noxious weeds are present, do not purchase the materials.

10.1.5 ORGANIC MATTER AMENDMENTS

10.1.5.1 Background

High quality topsoil is not always available in the quantities needed to meet the objectives of 

a revegetation project. In such cases, infertile subsoils can be augmented by the incorporation 

of organic matter and other soil amendments. This practice can be an important tool to begin 

the process of rebuilding a soil and reestablishing native vegetation. 

One immediate eff ect of incorporating organic matter into infertile subsoils is increased 

infi ltration. Water that would typically run off the soil surface during rainstorms now enters 

the soil. Amended subsoils also have greater permeability, and often increased water storage. 

Changes in these factors can improve the overall hydrology of the site, making soil less 

susceptible to runoff and erosion.

Incorporation of organic matter can often improve plant establishment and growth rates, 

especially if composted organic matter is used. Composted organic materials increase soil 

nutrients and rooting depth, which can create better growing conditions for native plant 

establishment. The use of non-composted organic materials, such as ground wood residues, 

can restrict plant establishment for the fi rst several years after incorporation because of the 

immobilization of nitrogen. In this section, we will discuss the substitution of non-composted 

organic matter when composted materials are not available, are too expensive, or are excessive 

distances from the project site. Sources of non-composted organic materials are almost always 

available on construction sites as a result of the clearing and grubbing of trees and shrubs, and 

can be made available through grinding or chipping operations.

Incorporated organic matter becomes the primary source of energy for soil organisms and, 

whether fresh or composted, is the driving force behind soil development. In the process of 

decomposition, soil organisms turn cellulose into complex organic compounds, while slowly 

releasing nutrients for plant growth. Some of the complex compounds act similarly to glues, 

sticking soil particles together into aggregates, which ultimately create soil structure. The slow 

decomposition of organic matter delivers a steady supply of nutrients to the establishing plant 

community for many years. 

The strategy behind many current revegetation projects is to obtain immediate cover with 

the use of seeds, fertilizers, and other amendments, without considering what is needed for 

long-term site recovery. It is not uncommon to fi nd good establishment of vegetative cover 

immediately (within a year) after revegetation work, but several years later fi nd that it was not 

sustainable. Life expectancy of many revegetation projects has often been found to be very 

short (Claassen and Hogan 1998). Incorporating organic matter takes a diff erent approach. 

This strategy puts more emphasis on the development of the soils and less on the quick 

establishment of vegetation. It is based on the premise that reestablishing native vegetation 

will create healthy, functioning soils on highly disturbed sites over time. This cannot happen 

without basic minimum soil components, such as an organic source, nutrients, and good soil 

porosity. These components of a soil must be in place if plant communities are to become 

sustainable. Incorporating organic matter into the soils of highly disturbed sites is an important 

component of meeting long-range revegetation objectives. 

10.1.5.2 Set Objectives

Section 10.1.3 discussed the use of organic matter as seedbed or seedling mulch. When used 

as mulch, organic matter protects the soil surface from erosion, enhances seed germination, 

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and, with time, breaks down and improves the surface soil properties. Applying organic matter 

on the soil surface is far easier and more practical than incorporating it into the soil. Why, then, 

incorporate organic matter? 

 · Improve soils of “diffi cult” parent materials,

 · Increase water-holding capacity,

 · Improve rooting depth,

 · Improve infiltration and drainage, and

 · Encourage quicker release and availability of nutrients and carbon.

Setting objectives clarify why this mitigating measure is being considered and helps defi ne the 

appropriate sources and application rates for incorporated organic matter.

“Diffi cult” Parent Material – The parent material from which soils are derived often plays an 

important role in how soils will respond to disturbances. Soils originating from granitic rock 

respond poorly to the removal of topsoil. Subsoils from this parent material have very high 

bulk densities and low permeability rates. They can “hardset” when dry, restricting root growth 

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Inset 10.5 – How Much is Soil Water-Holding Capacity Increased by Incorporating 

Organic Matter?

To determine whether there will be an immediate increase in the water-holding capacity 

of a soil as a result of organic matter incorporation, a test can be performed using readily 

available supplies (Note: This should be considered a “relative” test for available moisture, 

since wilting point is not determined).In the fi eld, collect a large amount of soil (at least 

several quart bags). Obtain samples of the organic matter amendment under consideration. 

Make 6 or more containers out of 3-inch PVC pipe by cutting them into 4-inch lengths. Secure 

cheese cloth with duct tape around the bottom of one tube. Make a fl at “end” piece for the 

tubes by cutting a plastic sheet (or using an old CD) and secure it to the bottom as well. 

In a bowl, mix several samples of organic matter to sieved soil (a mixing rate of 4.5 cups soil 

to 0.5 cups organic matter = 10% organic matter; 4 cups soil to 1 cup organic matter = 20%; 

3.5 cups soil to 1.5 cups organic matter = 30%). Place each mix in a PVC tube and fi ll to the 

top (the soil should be held in the tube by the cheese cloth and plastic). Lightly tamp the 

container against a surface and fi ll to the top of the tube. Identify the mix of soil and organic 

matter. As a control, or comparison, one tube must have no organic matter in the sample. 

Place each container in a 5-gallon bucket or plastic trash can (which must be taller than 

the length of the tubes). Fill the bucket with water just to the tops of the tubes (you might 

have to fi ll the bucket up to the top a few times) and keep them in the bucket for at least 

30 minutes, or as long as it takes to see thoroughly moistened soils. 

Remove the tubes from the water and let them drain. After several hours, detach the plastic 

bottoms (the soil should be held together by the cheese cloth) and place the ends of the 

tubes on a large stack of newspapers or paper towels. The paper will remove the excess 

water held at the bottom of the tube. Replace paper towels as they become saturated 

(Note: Place the plastic bottoms over the top of the tubes to prevent the soil at the surface 

from drying).

After 24 hours, record the weight of each tube. Remove the soil from the tube and weigh the 

tube. Dry soil at 221 °F (105 °C) in a drying oven. Unless a drying oven is available, purchasing 

one can be expensive. An alternative is drying each sample in a crockpot. These inexpensive 

appliances can reach temperatures of approximately 200 °F and it is possible to dry several 

samples in a day. When the sample is dry, weigh the sample. Calculate the percentage of 

soil moisture for each soil mix using the following equations (be sure to subtract the tube 

weights from the soil):

% soil moisture = (wet soil weight – dry soil weight) / dry soil weight * 100

If there is no increase in % soil moisture with the additions of organic matter over the soil 

with no organic matter additions, it means that in the short term, applying organic matter 

will not improve water-holding capacity. For a more accurate assessment, contact analytical 

laboratories that perform soil moisture tests. 221
and increasing runoff (Claassen and Zasoski 1998). Any positive eff ects of deep tillage are often 

short-lived on granitic subsoils (Luce 1997) because they quickly return to high bulk densities 

and soil strengths. Granitic soils can benefi t from the incorporation of organic matter, not only 

because of increased nutrients, but because soil physical properties are improved. Organic 

amendments lower bulk densities and help to form pathways for water entry, soil drainage, 

and root growth. Organic matter can also increase the water-holding capacity of these soils.

Soils derived from serpentine rock have also been identifi ed as diffi cult to revegetate because 

of heavy metals, low water-holding capacity, low nutrient levels, and low calcium to magnesium 

ratio. When disturbed, these sites can take decades to revegetate, producing a continual output 

of sediments. Incorporating compost into serpentine soils can greatly improve revegetation 

success by increasing water-holding capacity (Curtis and Claassen 2005). 

Water-Holding Capacity – The incorporation of organic matter can increase water-holding 

capacity of soils with less than 9% available water capacity (Claassen 2006). These include soils 

with sand, loamy sand, and some sandy loam textures, as well as soils high in rock fragments. 

Incorporating organic matter to increase water-holding capacity can be critical on arid or semiarid sites, or sites with very little summer rainfall. The increase in moisture-holding capacity 

depends on the type of organic matter and the degree of decomposition. Non-decomposed 

(fresh) organic sources, such as large wood chips and shredded wood fi ber, can actually 

decrease soil water-holding capacity because these large materials hold very little water (These 

materials can act similarly to gravels).A test for determining how much soil moisture will be 

increased or decreased by the incorporation of organic matter is described in Inset 10.5. From 

these results, the source and quantity of organic matter to incorporate can be determined. 

Rooting Depth – For species that have deep rooting requirements, such as trees and some 

shrubs, incorporating organic matter into the subsoil can increase rooting depth. This can be 

benefi cial for plant establishment and long-term site recovery, especially when applied to soils 

derived from “diffi cult” parent materials. Soils that are compacted can also benefi t from deep 

incorporation of organic matter. The incorporation of organic matter to deeper levels is often 

accomplished by applying a thick layer of organic matter to the surface, and then incorporating 

it to the desired depths with an excavator or backhoe. It is important that the organic matter is 

thoroughly mixed through the soil profi le during incorporation.

Infi ltration and Drainage – The hydrology of most disturbed soils is improved with organic 

matter incorporation. The degree to which infi ltration and permeability is improved depends 

on the size and shape of the organic source and application rates (see following sections). Finer 

textured soils lacking structure (e.g., clay loams, silty clay loams, and sandy loams) should have 

better infi ltration and permeability when organic matter is uniformly applied. This objective is 

applied in areas where water quality issues are high.

Nutrients and Carbon – Applying organic matter can assure that nutrients and carbon are 

available to decomposing soil microorganisms, which are essential for rebuilding a healthy 

soil. Typically this objective is applied to soils that are low in nutrients and carbon (e.g., sites 

lacking topsoil).

10.1.5.3 Select Organic Materials 

There is a range of organic material sources to consider. Developing a selection criteria based 

on the following characteristics can be helpful:

 · Source of organic matter,

 · Level of decomposition,

 · Carbon-to-nitrogen ratio (C:N), and

 · Size and shape of material.

Recognizing how these characteristics will help achieve the objectives for incorporating 

organic matter should guide the revegetation specialist in making the appropriate decision 

for each project.

Organic Sources – Most available organic sources originate from waste byproducts of 

agriculture, forestry, and landscape maintenance. They include yard waste (lawn clippings, 

leaves), wood residues (sawdust, bark, branches, needles, roots, and boles of trees and shrubs 

from landscape maintenance, land clearing, logging operations, or mills), manures (poultry or 

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222
cattle), agricultural waste products (fruits and vegetables) and biosolids (treated sewage sludge 

meeting EPA regulations). In the composting process, usually more than one source is used. A 

compost from one facility might include lawn clippings, leaves, yard waste, poultry manure, 

and ground wood fi ber, while another facility might use yard waste, ground wood fi ber, and 

biosolids. When biosolids are used in the composting process, the resulting material is referred 

to as co-compost.

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Inset 10.6 – Compost Production

The production and use of compost 

in the United States has fl ourished in 

the last 20 to 30 years as a result of a 

ban in many of states on yard wastes 

in landfi lls. Since 1988, the number 

of yard waste composting facilities in 

the United States has expanded from 

less than 1,000 in 1988 to over 3,500 

in 1994. With the formation of the 

Composting Council in 1989, research 

in compost manufacturing has 

increased signifi cantly.

Composting is the biological 

decomposition of organic matter under 

controlled aerobic conditions. To start 

the composting process, there must be 

organic matter, water, microorganisms, 

and oxygen (A). Heat is also needed, 

but is created by the microorganisms 

as they proliferate. Temperatures 

exceed levels necessary to kill most 

pathogens and weed species (B). 

With time, in a controlled composting 

environment, microorganisms release 

carbon dioxide and water from the 

organic matter. The rate at which 

these are released, and ultimately the 

composting time, is a function of the 

type of material being composted and 

the composting method.

A variety of composting methods have 

been developed over the years. Stateof-the-art facilities and equipment 

that control and monitor oxygen, 

moisture, CO2

, and temperature levels 

throughout the composting process 

can produce relatively uniform 

products. The picture shown in (C) is 

of a composting system that pumps 

oxygen through a pipe centered in the 

wrapped piles of compost. Temperature 

and carbon dioxide are controlled 

through a venting system (adapted 

from Epstein 1997).

Water Oxygen

Microorganisms

25 to 50%

Green Wastes

(Nitrogen)

50 to 75%

Brown Wastes

(Carbon)

1 to 12 Months

Compost

Pasteurization

Temperature

Insects and

Worms

Fungi and 

Actinomycetes

Bacteria

Time (One to 12 Months)

Compost

 ̊

F  ̊C

70

60

50

40

30

20

10

0

160

140

120

100

60

80

40

32

A

B

C

223
Each organic source has a unique nutrient composition. Green alfalfa, for example, has a very 

diff erent nutrient makeup than organic matter derived from wood residues of cleared rightof-way. Even within sources, there are very diff erent nutrient compositions (Figure 10.27). For 

example, most of the nutrients of trees are concentrated in the foliage and branches, and very 

little in the bole of the tree. A chipped slash pile composed of higher proportions of branches 

and foliage will contain far greater nutrients than a pile composed primarily of tree boles and, 

as such, would probably be a more preferred organic source.

As organic sources decompose, they contribute their combination of nutrients to the fertility of 

the soil. Knowing the source from which the organic matter was derived will give some indication 

of the amount of nutrients that might be supplied to the soil (Table 10.8). This information is 

important to determine whether target long-term nutrient levels will be achieved. Nutrient 

analysis reports should be obtained from facilities supplying the compost. Other sources of 

organic matter can be collected and sent to labs specializing in this type of testing (Inset 10.7).

Knowing the source of the organic matter might also identify contaminants that could potentially 

be harmful to plant growth. Additions of waste products, such as fl y ash and municipal and 

factory waste products can potentially decrease the quality of an organic source. Testing 

these materials for contaminants, 

pH, soluble salts, and bioassay (Table 

10.9) will identify potential problems 

with materials.

Level of Decomposition – Organic 

matter can be in various stages of 

decomposition; from fresh organic 

matter with minimal decomposition 

to compost that has undergone 

extensive decomposition. The level 

of decomposition is an important 

consideration when selecting an 

organic amendment. Additions 

of relatively undecomposed 

organic matter to the soil can have 

negative short-term eff ects on plant 

establishment and growth. 

“Fresh” organic matter is recently 

ground or chipped material that has 

undergone very little decomposition. 

These materials usually have very 

high C:N and will immobilize soil 

nitrogen for months to several years 

after incorporation, depending on the 

characteristics of the organic source. 

Very slow establishment of plants 

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Wood - Ponderosa pine and Douglas-fir 1,200:1 to 1,300:1

Materials C:N Ratio

Bark - Ponderosa pine and Douglas-fir 400:1 to 500:1

377:1

170:1

110:1

80:1

71:1

60:1

40:1

40:1 to 80:1

25:1 to 30:1

24:1

20:1

13:1

Wood - Red alder

Paper

Pine needles

Wheat straw

Bark - Red alder

Dry leaves

Dry hay

Leaves

Yard compost

Oat straw

Rotted manure

Alfalfa hay

Top soil 10:1 to 12:1

Table 10.8 – C:N for common sources of organic 

matter (from Rose and Boyer 1995; Epstein 1997; 

Claassen and Carey 2004; Claassen 2006). 

Figure 10.27 – Nutrients 

are held in diff erent 

portions of the forest 

biomass, as shown for old 

growth Pacifi c silver fi r. On 

a percentage basis, tree 

foliage is the storehouse for 

nutrients. Mulch derived 

from branches and foliage 

will have far greater 

nutrient content than 

mulch from bark and wood 

(adapted from Cole and 

Johnson 1981).

Nitrogen

Phosphorus

Potassium

Foliage

Tree Components

Nutrients (%) 1.25

1.00

0.75

0.50

0.25

0.00

Branches Bark Wood

224
should be expected when incorporating fresh organic matter unless a continuous source of 

supplemental nitrogen is applied (e.g., applications of slow release fertilizers, growing nitrogen 

fi xing plants). Nevertheless, applying fresh organic matter to highly disturbed soils can have 

a positive eff ect on slope hydrology and surface erosion. Fresh organic matter can increase 

infi ltration and permeability in poorly structured soils by creating pathways for water-fl ow. 

Incorporating fresh organic matter is not generally practiced in wildland revegetation. However, 

considering the expense of purchasing and transporting composted materials to remote sites, 

as well as the availability and abundance of road right-of-way material that is typically burned 

for disposal, this is an option that should be considered. If shredded or chipped road right-ofway material is to be incorporated into the soil, it should be allowed to age as long as possible 

in piles. To increase the rate of decomposition, the piles should be moved several times a year 

to add oxygen. 

Some organic sources have been stored in piles for long periods of time and are partially 

decomposed. They are darker in appearance than fresh sources, but the appearance of the 

original organic source can still be discerned (e.g., needles or leaves are still identifi able). 

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Inset 10.7 – The Seal of Testing Assurance (STA) Program

Just as many products at the local market have seals of approval (e.g., “Approved by the 

FDA” or “USDA Inspected”), the United States Composting Council operates an approval 

system for composting facilities. The Seal of Testing Assurance (STA) is a voluntary program 

that requires compost manufacturers to regularly test their composts using an approved 

third-party testing facility. The procedures for sampling and testing are outlined in the Test 

Methods for the Examination of Composting and Compost (TMECC) protocols. The STA 

program takes the worry out of purchasing compost because you know that you can be 

assured that the company is reputable. You can purchase compost from companies that do 

not participate in the STA program (when the job site is in the back country you might have 

to do this), but this leaves the sampling and testing up to you. This involves traveling to the 

compost piles, systematically collecting samples from the compost piles, sending them to a 

qualifi ed lab to run TMECC tests, and interpreting the results when you get them back. STA 

laboratories can be found at <http://www.compostingcouncil.org> (after Alexander 2003).

Test Parameters Test Methods Composted Material

Physical Contaminates

(man-made inerts)

Man-made inert removal and classification

(TMECC 03.08-C)

Arsenic, Cadmium, Copper, Mercury, Manganese,

Molybdenum, Nickel, Lead (TMECC 04.06)

1:5 slurry pH (TMECC 04.11-A)

Electrical conductivity using

1:5 Slurry Method (dS/m)

% seedling emergence and relative

seedling vigor (TMECC 05.05-A)

% wet weight (TMECC 03.09-A)

% by dry weight, loss on ignition (TMECC 05.07A)

Respirometry. Carbon dioxide evolution rate -

mg CO2-C per g OM per day (TMECC 05.08B)

(TMECC 05.02-A)

<1%

Meets US EPA, 40 CFR

503 regulations

5.0 -8.5

<5

>80% of control

30 - 60

25 to 60%

<8

<25

% of compost by dry weight passing a

selected mesh size, dry weight

(TMECC 02.12-B)

* 3”(75 mm) 100%

* 1”(25 mm), 90 -100%

* 3/4”(19 mm), 65 -100%

* 1/4”(6.4 mm), 0 -75%

* Maximum particle length

 of 6”(152 mm)

Trace Contaminants

pH

Soluble Salts

Bioassay

% Moisture Content

Total Organic Matter

Stability

C:N Ratio

Particle Size

Table 10.9 – General specifi cation ranges for composted materials for manufactured topsoil 

(modifi ed after Alexander 2003; CCREF and USCC 2006).

225
These materials are sometimes referred to as “aged.” Because only partial decomposition has 

occurred, C:N is lower than fresh organic matter. Nitrogen immobilization, however, should 

still be expected for a signifi cant period of time after incorporation. Aged organic sources 

have not typically undergone extensive heating, like composts, and they can contain seeds of 

undesirable weeds.

Compost results from the controlled biological decomposition of organic material. The resulting 

heat generated in the process sanitizes the material. The end product is stabilized to the 

point that it is benefi cial to plant growth (Alexander 2003a, 2003b). During the early stages 

of composting, heat is generated at temperatures that are lethal to weed seeds, insects, and 

pathogens (Inset 10.6). Fresh, moist compost piles will usually generate heat in the fi rst few days 

of composting, reaching 140 to 160 °F, which will kill most pathogens and weed seeds (Epstein 

1997; Daugovish and others 2006). The resulting material is a relatively stable, sanitized product 

that is very dark brown to black in color. Composts are very suitable materials for increasing the 

water-holding capacity of sandy soils, increasing nutrient supply, and enhancing soil infi ltration 

and permeability rates. 

Carbon-to-Nitrogen Ratio – The carbon-to-nitrogen ratio (C:N) is one of the most important 

characteristics to consider when selecting a source of organic matter. It is an indicator of 

whether nitrogen will be limiting or surplus (See Section 5.5.3.1). The higher the C:N, the greater 

the likelihood that nitrogen will be unavailable for plant uptake. When an organic source 

with high C:N is incorporated into the soil, carbon becomes available as an energy source for 

decomposing soil organisms. Soil microorganisms need available nitrogen to utilize the carbon 

source. Not only do microorganisms compete with plants for nitrogen, they store it in their cell 

walls, making it unavailable for plant growth for long periods of time. As the carbon sources 

become depleted, the high populations of soil microorganisms die and nitrogen is released for 

plant growth. 

When C:N is greater than 15:1, available nitrogen is immobilized. As ratios dip below 15:1, nitrogen 

becomes available for plant uptake. Most fresh and aged organic sources have C:N greater than 

15:1 (Table 10.8) and will immobilize nitrogen for some period of time when incorporated into 

the soil. When these same materials are composted, C:N approaches or even falls below 15:1. 

These materials will then provide a source of nitrogen to the soil. Co-composts, for instance, can 

have ratios between 9:1 and 11:1, indicating they are a ready source of available soil nitrogen. 

Since these materials provide nitrogen, they are often considered fertilizers (Ratios below 10:1 

are typically labeled as fertilizers).

The period of time that nitrogen remains immobilized in the soil is dependent on several factors: 

 · Climate. High moisture and warm temperatures are important for accelerating 

decomposition rates. For example, organic matter will decompose faster in the coast 

range of Oregon than in the mountains of Idaho.

 · Quantity of incorporated organic matter. The more organic matter that is applied, the 

longer the immobilization. A small amount of incorporated sawdust will immobilize 

very little nitrogen as compared to several inches of the same material.

 · C:N of organic amended soil. The combined C:N of soil and incorporated organic matter 

gives an indication of how the type and rate of incorporated organic matter will aff ect 

the soil C:N. An amended soil with a high C:N will have a longer immobilization period 

than a soil with a lower C:N.

 · Size and shape of organic matter. The more surface area of the organic source, the 

faster decomposition will take place. A fi ne compost will decompose faster than a 

coarse, screened compost.

 · Nitrogen fertilization or fi xation. Nitrogen supplied from fertilizers or nitrogen-fi xing

plants will speed up decomposition rates.

It is not easy to predict how long nitrogen will be immobilized in a soil. The variety of available 

organic sources, unique soil types, and range of climates of the western United States make this 

diffi cult. For practical purposes, it should be assumed that without supplemental additions of 

nitrogen (from fertilizers or nitrogen-fi xing plants), the immobilization of nitrogen in soils with 

high C:N will be in the order of months, if not years. To give some idea of decomposition rates, 

Claassen and Carey (2004) found that partially composted yard waste with a C:N of 18:1 took 

over a year for nitrogen to become available under aerobic incubation testing conditions.

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A high C:N might be benefi cial to soil aeration and water movement because it does not break 

down as fast as material with lower C:N. For example, the incor poration of alfalfa hay (C:N =13:1) 

will decompose quickly, and the eff ects on soil structure might be short-lived. On the other 

hand, wheat straw (C:N = 80:1) or pine needles (C:N = 110:1) can be eff ective for several years. 

High C:N materials are also a longer-term energy source to soil organisms that help cre ate a 

stable soil structure.

Nitrogen based fertilizers can be applied to off set higher soil C:N and make soil nitrogen 

available for plant growth. Section 10.1.1 discusses fertilizer strategies for reducing the eff ects 

of high C:N soils.

Size and Shape – The range in sizes and shapes of organic matter plays a role in how quickly 

organic matter breaks down in the soil. Particles with greater surface area to volume ratios 

should decompose faster than particles with less surface area to volume. Chipped wood, for 

instance, has a low surface area to volume ratio and would take longer to break down than long 

strands of ground wood or fi ne screened sawdust, which have greater surfaces areas. 

The particle size and shape of the organic source can also be important in slope hydrology 

by increasing infi ltration and permeability rates. Long, shredded wood fi ber, for example, can 

create long passageways for water. If applied at high enough rates, long fi bers can overlap, 

creating continuous pores that will increase drainage rates. Wood chips applied at the same 

rates are less likely to form continuous routes for water drainage because of their shape.

Large undecomposed wood can signifi cantly reduce soil water storage due to low waterholding capacity of the material. Incorporating large, undecomposed woody organic matter 

into soils with low water-holding capacities should be tested fi rst to determine its eff ect 

(See Section 10.1.5.1). 

10.1.5.4 Determine Application Rate

The rates for applying organic matter should be based on the objectives for organic matter 

incorporation. Each objective discussed in Section 10.1.5.2 will yield diff erent application rates. 

For example, a project objective to increase permeability would require the addition of 6 inches 

of compost mixed into 24 inches of soil. This is a far greater quantity than if the objective was to 

increase nutrient supply, which would require 2 inches of compost added to the top 12 inches 

of soil. 

Determining rates of organic matter needed to improve nutrient status can follow the process 

outlined for calculating fertilizer rates in Section 10.1.1.2. If a nutrient, specifi cally nitrogen, is 

found to be defi cient, the amount of organic material to apply must be determined. A nutrient 

analysis is necessary to make these determinations. Figure 10.28 gives an example of how to 

calculate the amount of organic matter to incorporate to meet minimum levels of nitrogen.

When organic matter is used to increase infi ltration and permeability of a soil, a rate of 25% 

organic matter (by volume) to 75% soil (by volume) has been suggested by several researchers 

(Claassen 2006). This would require 4 inches of organic matter be incorporated for every 

9 inches of soil. Actual fi eld trials could be installed prior to construction to measure the eff ects 

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Figure 10.28 – The following calculations can be used to determine the amount of compost to 

apply to a site. They are based on laboratory test results of the compost and threshold nitrogen 

levels obtained from reference sites.

A 10 lbs/cu yd

From laboratory report — most

labs will report out nutrients in

lbs/cu yd of material

Total nitrogen (or other

nutrient of interest) in compost

D 0.6 in

Thickness of compost to apply to the Minimum application depth: C/135 = site to meet minimum thresholds

C 77 cu yd/ac Volume of compost to apply

to the site to meet minimum thresholds Minimum application rates: B/A =

B 769 lbs/ac

Determine from reference sites or 

minimum thresholds from literature 

(See Figures 10.1 and 10.2)

Nitrogen deficit

227
of soil amendments on infi ltration. By incorporating several rates of organic matter on plots 

in disturbed reference sites near the project, the infi ltration rates of each treatment could be 

determined using rainfall simulation equipment.

If the objective for incorporating organic matter is to increase the soil’s available water-holding 

capacity, the rate of organic matter application should be based on achieving a total available 

water-holding capacity for the desired vegetation of the project area (Setting these targets is 

discussed in Section 5.3).Inset 10.5 shows one method of determining relative water-holding 

capacity of amended soils.

10.1.5.5 Assure Product Quality

Purchasing compost requires a set of contract specifi cations that assure product quality. 

Table 10.9 is a “model specifi cation” developed for the Department of Transportation (DOT) 

by the Composting Council Research and Education Foundation (Alexander 1993b) for 

composts used as soil amendments on roadways. The tests are based on the Test Method for 

the Examination of Composting and Composts (TMECC) protocols. These are general quality 

guidelines and can be broadened or made more constraining depending on the specifi cs of 

the project. When considering purchasing compost or any other type of organic matter from a 

manufacturer, it is important to request the latest lab analysis. A Seal of Testing Assurance (STA) 

facility (Inset 10.7) will have these reports available while others might not. It is important that 

these tests be run by STA laboratories. It is a good practice to visit the location of the organic 

sources to determine whether there are undesirable or noxious weeds on or nearby the piles. If 

these species are present, materials should not be purchased.

10.1.6 LIME AMENDMENTS

10.1.6.1 Introduction 

Agricultural lime is used when soil pH of a disturbed site needs to be raised to improve plant 

survival and establishment (See Section 5.5.5, pH and Salts). Liming low pH soils improves 

plant growth by 1) reducing aluminum toxicity, 2) increasing phosphorus and micronutrient 

availability, 3) favoring symbiotic and non-symbiotic nitrogen fi xation, 4) improving soil 

structure, and 5) enhancing nitrifi cation (Havlin and others 1999). 

Each plant community has an optimal pH range. Plant communities dominated by conifers, for 

instance, function well between pH 5.0 to 6.5, whereas grass-dominated plant communities in 

arid climates perform well between pH 6.5 and 8.0. Liming is not an easy operation on drastically 

disturbed lands. Liming materials must be incorporated into the soil profi le for maximum 

eff ectiveness. This application is very diffi cult on steep rocky slopes, which are typical of road 

construction in mountainous terrain.

10.1.6.2 Set pH Targets 

It is important to set a realistic post-construction target pH when considering liming because 

large quantities of lime are needed for even small changes in soil pH. For example, raising an 

existing soil pH of 5.5 to pH 6.5 takes nearly twice the amount of lime necessary to raise it to 

pH 6.0. A half point pH diff erence in this case can result in an increase of over 1,000 lb/ac in 

application rates. 

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Slag

Material

Chemical

Formula CCE

Agricultural limestones

Marl

Pure limestone

Pure dolomite

Hydrated lime, slaked lime, builders’ lime

Burned lime, unslaked lime, quicklime

CaSiO3

CaCO3

CaCO3

CaCO3

CaMg(CO3)2

Ca(OH)2

CaO

60-90

70-90

70-90

100

110

120-135

150-175

Table 10.10 – Liming materials are 

rated by how well they neutralize the soil 

using pure limestone as the baseline of 

100%. The rating system is called calcium 

carbonate equivalents (CCE). Values for 

some commercially available products are 

shown below (Campbell and others 1980; 

Havlin and others 1999). 

228
As discussed in previous sections, it is important to understand the characteristics of the 

reference site topsoils and try to recreate these conditions after construction. If the postconstruction surface soils have a lower pH than the reference site topsoils, then liming can 

be used to raise pH. On a project where topsoil is removed and not replaced, the diff erence 

between the pH of the topsoil and the subsoil should be determined. When the pH of the 

subsoil is signifi cantly lower than the topsoil, liming to raise soil pH to reference topsoil levels 

(target levels) should be considered. Although it might not always be practical to raise pH 

of post-construction soils to reference topsoil values, a minimum pH target of 5.5 should be 

considered for most sites. This minimum standard would make most soils below pH 5.5 good 

candidates for liming. 

10.1.6.3 Select Liming Materials 

There are several types of liming materials commercially available (Table 10.10) and selection 

should be based on costs, reactivity, eff ects on seed germination, and composition of the 

material. All liming materials will raise soil pH, but not at the same level as pure limestone. 

To account for this, all commercially available liming materials are rated against pure limestone 

for neutralizing eff ects. The rating system is called calcium carbonate equivalent (CCE). Burnt 

lime (CaO) for instance, might have a CCE of 150, which means that it has a 50% greater 

neutralizing capacity than pure limestone and much less of this material needs to be applied 

to increase pH. A low CCE material, such as slag, might have a CCE of 60, which means that it 

has 40% less neutralizing capacity. Liming materials with high CCE, like Ca(OH)2

 (slaked lime, 

hydrated lime, or builders lime) and CaO (unslaked lime, burned lime, or quicklime), can be 

caustic to germinating seeds and, if used, should be applied several months before sowing 

(Havlin and others 1999).

The particle size of the liming material determines how quickly the pH of a soil will increase. 

The fi ner the material, the faster soil pH will increase. For instance, a lime material passing a 

100-mesh screen reacts faster and takes less quantity than material passing a 50-mesh screen. 

Finer lime materials are more expensive to purchase. If very fi ne lime is to be used in surface 

application, it should meet the following size requirements: 100% passing a 100-mesh sieve 

and 80% to 90% passing a 200-mesh sieve.

10.1.6.4 Determine Liming Rates

Determining how much liming material to apply is based on these factors: 

 · Soil texture. Soil texture plays an important role in lime requirements because the 

higher the clay content, the more lime must be added to the soil. A soil with a clay loam 

texture requires over 3 times more lime to raise the pH from 5.0 to 6.0 than a sandy 

soil. This is because fi ner textured soils and organic matter have a higher propensity to 

attract and store bases released from liming materials (Inset 10.8). 

 · Soil organic matter. Soil organic matter (in humus form) has a high CEC and requires 

more lime material to raise the pH.

 · Percentage of rock fragments. Rock fragments have little to no CEC because they 

are massive and typically unweathered. Rocky soils will require less lime materials to 

raise pH.

 · Depth of liming material. Lime materials are relatively insoluble and only change the 

pH of the soil around where they were placed. Liming rates are adjusted based on the 

soil depth to which the lime material is mixed.

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Inset 10.8 – Cation Exchange Capacity (CEC)

The capacity of a soil to hold positive ions (referred to as bases or cations) is called the cation 

exchange capacity (CEC). A soil with a high CEC holds a much greater amount of cations, 

such as calcium and magnesium, than a soil with low CEC. For this reason, a high CEC soil 

requires more liming material to raise it to the same pH level. Cation exchange capacity is 

directly related to the amount of clay and organic matter present in the soil – the higher the 

clay or organic matter content, the higher the CEC. Rock fragments have little or no CEC, 

since they are massive in structure. Rates of liming on high coarse fragment soils must be 

reduced proportionally. 

229
 · Lime material composition. Each liming material is rated by how well it neutralizes the 

soil. Less materials with high CCE (See Section 10.1.6.3) are required as compared to low 

CCE materials.

 · Fineness of liming material. The fineness of the liming material determines how quickly 

the pH will change. Very fi ne materials change pH quicker than coarse materials. 

Therefore, less quantity of fi ner grade materials will be required for immediate pH 

soil change.

There are two methods for determining liming application rates: approximation and SMP 

(Shoemaker-McLean-Pratt) Buff er methods. For an initial estimate of how much liming material 

might be needed to raise soil pH to target levels, the approximation method can be employed. 

However, if liming will actually be done on a revegetation project, the SMP Buff er method 

should be used for calculations.

Approximation Method – For a quick approximation of lime application rates, the calculations 

shown in Figure 10.29 and Figure 10.30 are used. In the examples shown in these two fi gures, 

the topsoil was removed, leaving a gravelly, sandy loam subsoil at the surface. This material had 

a pH of 5.0. The target pH, based on the reference site for this area, was 6.0. The site was on a very 

steep slope where incorporating the limestone was not feasible (See Section 10.1.6.5). It was 

therefore decided to place the lime on the surface of the soil through hydroseeding operations. 

The surface had been left rough so that, over time, some of the liming materials would naturally 

become incorporated into the surface through soil movement. The incorporation depth was 

set between 3 to 4 inches (0.3 ft) based on this assumption. 

Generalized curves shown in Figure 10.30 were used to determine the amount of limestone to 

add to raise the pH. On the baseline of the graph, rates of limestone in lb/ac that correspond 

to the surface soil pH (C = 900) and the target pH (D = 2,800) were determined from pH levels 

located on the sandy loam curve. The rate of limestone for the surface soil was subtracted 

from the target rate to give the quantity of limestone to add to 7 inches of soil (the depth of 

incorporation upon which these graphs were based). In this example 1,900 lb/ac of limestone 

was needed to achieve the target pH (2,800 less 900). This rate was subsequently reduced to 

639 lb/ac to compensate for the volume of rock fragments and the shallow incorporation depth 

(3 inches instead of 7 inches). Since dolomite, which has a higher CCE value, would be applied, 

there would be less of this material needed (581 lb/ac).

SMP Buff er Method – For much greater accuracy, lab testing facilities off er the SMP Buff er 

Method for determining the lime requirement for a disturbed soil. The results from this test are 

reported in a table that includes the quantity of lime needed to raise the soil sample to pH 7. 

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A pH of disturbed soil: 5 From pH test of disturbed soils

I dolomite Based on availability and cost of material 

H 639 Amount of limestone to raise soil to

target pH

Type of liming material:

J CCE of liming material: 110 From Table 10.10 

K H / (J /100) = 581 lbs/ac Total amount of material to apply 

G 2,800 lbs/ac

lbs/ac

From Figure 10.30 (D)

(G - F) * (E /0.58) * (100 - D) / 100

F 900 lbs/ac From Figure 10.30 (C)

Limestone equivalent

E 0.3 feet The depth the lime material will be 

incorporated

Limestone equivalent for 

disturbed soil pH 

Incorporation depth: 

D Rock fragments: 35 % From field surveys of disturbed soils

C Soil texture: sandy loam From field surveys of disturbed soils

B Target pH: 6 Target pH of reference site topsoil

Figure 10.29 – This spreadsheet, along with Figure 10.30, provide the steps necessary for 

determining the approximate amount of liming material to apply. 

230
The information can be graphed and used in a similar fashion to the example in Figure 10.30. 

The SMP test is well adapted for soils with pH values below 5.8 and containing less than 10% 

organic matter (McLean 1973).

10.1.6.5 Apply Liming Materials

Limestone materials are commonly applied in powder form through fertilizer spreaders 

or hydroseeding equipment. Fine limestone materials can be diffi cult to apply in dry form 

through fertilizer spreaders. Pelletized limestone, which is very fi nely ground material that 

has been processed into shot-sized particles, is easy to handle and can be used in fertilizer 

spreaders. Hydroseeding equipment, however, is probably the best method for spreading 

liming materials, especially very fi ne liming materials. 

Since liming materials are relatively insoluble in water, surface applications of lime, without 

some degree of soil mixing, renders the lime ineff ective for immediate correction of subsoil 

acidity. Several studies have indicated that it can take more than a decade for surface-applied 

lime (not incorporated) to raise soil pH to a depth of 6 inches (Havlin and others 1999). It is 

important, therefore, to incorporate liming materials into the soil at the depth where the pH 

change is desired. 

Incorporation can be accomplished on gentle slope gradients using tillage equipment, such as 

disks and harrows (See Section 10.1.2, Tillage). Liming materials can be mixed on steep slopes 

using an excavator. However, if equipment is not available for mixing on steep sites, applying 

very fi ne liming materials through hydroseeding equipment is a possible way of raising pH. 

This method requires the use of very fi nely ground limestone (Havlin and others 1999). This 

product raises pH faster, and depending on the soil type, can move a short distance into the 

soil surface. Nevertheless, with surface-applied limestone, it should be assumed that soil pH 

will not change much deeper than 3 inches below the soil surface. 

10.1.7 BENEFICIAL SOIL MICROORGANISMS

10.1.7.1 Background

Benefi cial microorganisms are naturally occurring bacteria, fungi, and other microbes that 

play a crucial role in plant productivity and health. Some types of benefi cial microorganisms 

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Sand

(CEC=5)

Limestone (lbs/ac)

pH

Sandy Loam (CEC=10)

Silty Loam (CEC=15)

Clay Loam (CEC=25)

B

D

E

0 4.5

5

5.5

6

6.5

1,000 2,000 3,000 4,000 5,000 6,000

A

C

Figure 10.30 – This chart can be used to approximate the liming application rates for disturbed 

soils. The chart is based on measuring pH changes of four soil textural classes as limestone is 

incorporated into the surface 7 inches of soil (chart modifi ed from Havlin and others 1999). 

For example, a sandy loam soil has an existing pH of 5.0 (A) and a target pH after liming of pH 

6.0 (B). The amount of limestone to apply (E) is 1,900 lb/ac, which is calculated by subtracting 

900 (C) from 2,800 (D). More accurate lab results obtained from the SMP Buff er method for 

determining lime requirements can be substituted for values obtained in this graph.

231
are called “microsymbionts” because they form a symbiotic (mutually benefi cial) relationship 

with plants. In natural ecosystems, the root systems of successful plants have several microbial 

partnerships that allow them to survive and grow even in harsh conditions (Figure 10.31). 

Without their microsymbiont partners, plants become stunted and often die. Frequently, these 

failures are attributed to poor nursery stock or fertilization, when the real problem was the 

absence of the proper microorganism. 

As discussed in Section 5.3.5, benefi cial microorganisms should be considered as part of 

an overall strategy to conserve existing ecological resources on the site, including existing 

benefi cial soil microorganisms. These strategies include:

 · Minimizing soil disturbance,

 · Conserving and reapplying topsoil and organic matter,

 · Leaving undisturbed islands or pockets on the project site, and

 · Minimizing use of fast-release fertilizers.

On projects where soil disturbance will be minimal, or where healthy topsoil is still present and 

contains functional communities of benefi cial microorganisms, reintroducing the organisms 

will usually not be necessary. However, most road projects involve severe disturbances and 

so healthy populations of benefi cial microorganisms may be depleted or even absent. Soil 

compaction and removal of topsoil which is routine during road construction is particularly 

detrimental to benefi cial soil microorganisms. Also, benefi cial bacteria and fungi do not survive 

in soil in the absence of their host plants and so are killed during soil removal and stockpiling. 

Reintroducing benefi cial microorganisms is therefore a key part of roadside revegetation.

Appropriate benefi cial microorganism can be reintroduced by “inoculating” seeds as they 

are sown in the fi eld or in the nursery, or by introducing the microorganism in the planting 

hole. Inoculated plants may establish more quickly with less water, fertilizer, and weed control, 

thereby reducing installation costs. Healthy, sustainable plant communities are our ultimate 

goal in roadside revegetation; inoculation can help accelerate the process. 

The two most important microsymbionts for revegetation projects are mycorrhizal fungi and 

Roadside nitrogen-fi xing bacteria.

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Figure 10.31 – Many plants rely on symbiotic relationships to survive and grow in nature (A). 

The mushrooms under this spruce are the fruiting bodies of a benefi cial fungus that has formed 

mycorrhizae on the roots (B). 

A B

232
10.1.7.2 What are Mycorrhizae?

Mycorrhizae are one of the most fascinating symbiotic relationships in nature. “Myco” means 

“fungus” and “rhizae” means “root”; the word “mycorrhizae” means “fungus-roots.” The host 

plant roots provide a convenient substrate for the fungus, and also supply food in the form 

of simple carbohydrates. In exchange for this free “room-and-board”, the mycorrhizal fungus 

off ers benefi ts to the host plant:

Increased Water and Nutrient Uptake – Benefi cial fungi help plants absorb mineral nutrients, 

especially phosphorus and micronutrients such as zinc and copper. Mycorrhizae increase 

the root surface area, and the fungal hyphae access water and nutrients beyond the roots 

(Figure 10.32A). When plants lack mycorrhizae, they become stunted and sometimes chlorotic 

(“yellow”) in appearance.

Stress and Disease Protection – Mycorrhizal fungi protect the plant host in several ways. With 

some fungi, the mantle completely covers fragile root tips (Figure 10.32A) and acts as a physical 

barrier from drying, other pests, and toxic soil contaminants. Other fungal symbionts produce 

antibiotics that provide chemical protection. 

Increased Vigor and Growth – Plants with mycorrhizal roots survive and grow better after 

they are planted out on the project site. This eff ect is often diffi cult to demonstrate but can 

sometimes be seen in nurseries where soil fumigation has eliminated mycorrhizal fungi from 

seedbeds. After emergence, some plants become naturally inoculated by airborne spores and 

grow much larger and healthier than those that lack the fungal symbiont (Figure 10.32B).

Mycorrhizal fungi form partnerships with most plant families, and three types of mycorrhizae 

are recognized: 

 · Ectomycorrhizal fungi (ECM) have relatively narrow host ranges and form partnerships 

with many temperate forest plants, especially pines, oaks, beeches, spruces, and fi rs.

 · Arbuscular mycorrhizal fungi (AMF) are also known as endomycorrhizae or vesiculararbuscular mycorrhizae. These fungi have wide host ranges and are found on most wild 

and cultivated grasses and annual crops, most tropical plants, and some temperate tree 

species including cedars, alders, and maples.

 · Ericoid mycorrhizal fungi form partnerships with the Epacridaceae, Empetraceae, and 

most of the Ericaceae; plants aff ected include blueberries, cranberries, crowberries, 

huckleberries, azaleas, rhododendrons, and sedges. Because these mycorrhizal 

associations involve unique species of fungi, few commercial inoculants are available 

and the best option is to use soil from around healthy plants.

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Figure 10.32 – Mycorrhizal fungi off er many benefi ts to the host plant. The fungal hyphae 

increase the area of absorption for water and mineral nutrients, whereas fungal mantle 

covers the root and protects it from desiccation and pathogens (A). In fumigated nursery soils, 

inoculated seedlings are much larger and healthier than those that lack the fungal partner (B).

A B

233
For restoration purposes, the 

important thing to remember is 

that diff erent plant species have 

specifi c fungal partners. ECM fungi 

are generally specifi c to one genus 

or group of plants whereas the same 

AMF fungus can colonize a wide 

variety of species. In addition, the 

three types of mycorrhizal fungi have 

to be inoculated diff erently. ECM 

species have airborne spores that can 

reinoculate soils naturally over time, or 

the spores can be harvested and used 

to inoculate nursery stock. On the 

other hand, the spores of AMF species 

are large and released underground 

and so cannot reinoculate plants 

very quickly. This makes artifi cial 

inoculation even more critical. 

Conserving existing topsoil and 

organic matter is a key practice 

to protect existing populations 

of benefi cial microorganisms. If 

disturbance will take place, then other 

interventions will be necessary to 

introduce the key microsymbionts for 

the plants you are trying to establish. 

Consider the needs for mycorrhizal 

inoculants. Are the species to be 

established endomycorrhizal, 

ectomycorrhizal, ericoid or nonmycorrhizal? The selection of the 

mycorrhizal inoculants must be 

based on the target host plants and 

the site condition. Conifer seedlings, 

for example, require very specifi c 

ectomycorrhizal fungi for successful 

inoculation. Endomycorrhizal species, 

on the other hand, are broad in 

range and therefore a general mix 

of several endomycorrhizal species 

can be utilized for a broader range 

of plants. Knowing which species 

you are working with is essential in 

order to match the plants with their 

appropriate microsymbiont partners. 

10.1.7.3 Sources and Application 

of Ectomycorrhizal Fungi

Three common sources of ECM 

inoculants are soil, spores, or pure 

culture vegetative inoculum. 

Soil – Topsoil, humus or duff from 

beneath ECM host plants can be used 

for inoculum if done properly. Because 

disturbance and exposure to direct sunlight may kill these benefi cial fungi, soil inoculation 

must be done as quickly as possible. Soil inoculum can also be collected under the same plant 

species adjacent to the project site (Figure 10.33A). Small amounts should be collected from 

several diff erent locations and care should be taken not to damage the host plants. If topsoil 

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Figure 10.33 – Soil inoculum can be collected from 

adjacent plants if done carefully (A). Inoculum can 

also be made from the spores of mushrooms (B), 

puff balls, or truffl es (C) collected from around the 

proper host plant.

A

B

C

234
and organic matter are not available on the project site, spores or commercial inoculants can 

be used instead. 

Spores – Spore suspensions are sometimes available from commercial suppliers. However, the 

quality of commercial sources can be variable so it is important to verify the quality of the 

inoculum. It is possible to make your own inoculum from spores. Collect ripe fruiting bodies of 

mushrooms (Figure 10.33B), puff balls, or truffl es (Figure 10.33C) from beneath healthy plants. 

Then, rinse and pulverize them in a blender for several minutes to make a slurry. Fungal spores 

do not have a long shelf-life and should be applied immediately.

Pure Culture Inoculum – Mycorrhizal fungi are available commercially as pure cultures, usually 

in a peat-based carrier (Figure 10.34). Most commercial sources contain several diff erent species 

of ECM. Because this type of inoculum is made from pure fungal cultures and does not store 

well, it is rarely available from suppliers. 

Application rates and methods for ectomycorrhizal inoculums will vary by species. Since these 

mycorrhizal fungi are very specifi c to their host species, it is important to work closely with 

company representatives when using ectomycorrhizal inoculum. Nurseries may inoculate 

plants; if this service is desired, it must be stated in the seedling-growing contract. Some 

ectomycorrhizal fungi products can be incorporated into the nursery growing media prior to 

sowing (Figure 10.34A) or a liquid slurry of fungal spores can be applied during the growing 

season. However, there is no guarantee that the plants will still be colonized when they are 

planted at the project site. 

Other ectomycorrhizal fungal inoculums are applied at the time of planting and here the 

objective is to get the inoculum in contact with the plant roots. Some formulations are mixed 

with water and the slurry is applied to the roots of nursery stock. Tablets or packets can be 

placed in the planting hole (Figure 10.34B). However, the eff ectiveness of many of these 

applications has not been verifi ed by research under roadside revegetation conditions. 

Verifying the Eff ectiveness of ECM Inoculation – Luckily, it is fairly easy to recognize ECM as 

the fungi can be seen with the naked eye on the root system. Short feeder roots should be 

examined for a cottony-white appearance on the roots or a white or brightly colored mantle 

or sheath over the roots (Figure 10.35). Unlike pathogenic fungi, mycorrhizae will never show 

signs of root decay and the mycelia around the root will be visible. Sometimes, mushrooms 

or other fruiting bodies will occasionally appear alongside their host plants. For verifi cation, 

it is recommended that plant samples be sent to a laboratory where they can also provide a 

numerical rating of inoculation eff ectiveness. 

10.1.7.4 Sources and Application of Arbuscular Mycorrhizal Fungi

The two main sources of AMF inoculants include “pot culture,” (also known as “crude” inoculant), 

and commercially available pure cultures.

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Figure 10.34 – Commercial sources of ectomycorrhizal inoculum are available in several forms: 

pure cultures grown on peat moss or vermiculite (A) are perishable but spore-based products 

can be applied as root dips. Tablets and packets are put in the hole during planting.

A B

235
Nursery Pot Culture – This option 

is only viable in a nursery when 

plants are being grown for a specifi c 

restoration project, and is unique 

to AMF fungi because of their wide 

host range. A specifi c AMF is acquired 

either commercially or from a fi eld site 

as a starter culture, and then added to 

a sterile potting medium. A host plant 

such as corn, sorghum, clover, or an 

herbaceous native plant is then grown 

in this substrate; as the host grows, 

the AMF multiply in the growing 

medium (Figure 10.36A). The shoots 

of host plants are removed and the 

substrate, now rich in roots, spores, 

and mycelium, is chopped up (Figure 

10.36B). The resultant inoculum can 

then be incorporated into growing 

media or planting beds before seeds 

or cuttings are sown. This is a highly 

eff ective technique for propagating 

AMF in the nursery and could also 

be used on the planting site. For 

details refer to Arbuscular Mycorrhizas: 

Producing and Applying Arbuscular 

Mycorrhizal Inoculum (Habte and 

Osorio 2001). 

Commercial Products – Several 

brands of commercial AMF inoculants 

are available, and usually contain a 

mix of several fungal species. Because AMF spores are so small and fragile, they are mixed with 

a carrier such as vermiculite or calcined clay to aid in application. Coarser textured products 

(Figure 10.37A) are meant for incorporation into soil or growing media, and fi ner-textured 

products (Figure 10.37B) are applied as wettable powders through sprayers or injected into 

irrigation systems. Inoculation eff ectiveness has been shown to vary considerably between 

diff erent products (Figure 10.37C), so it is wise to install tests before purchasing large quantities 

of a specifi c product. Laboratories can provide a live spore count which is the best measure of 

inoculum quality. 

Application of AMF Inoculants – Because AMF spores are relatively large, ensuring that spores 

come in direct contact with the root systems or seeds is critical. Spores will not easily pass 

through irrigation injectors or nozzles, and do not move downward or through the soil into the 

soil with water. Therefore, applying AMF inoculum as a topdressing is not a good option. AMF 

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Figure 10.36 – Because of their wide host range, AMF fungi can be raised on host plants (A) and 

their roots chopped-up for inoculum (B).

A B

Figure 10.35 – Ectomycorrhizae are visible on 

plant root systems as white or colored structures 

with a cottony or felt-like texture. 

236
inoculums typically come in a granular form with diff erent grades of fi neness. Coarse grade 

products (Figure 10.37A) are mixed in the soil prior to sowing seed. Finer grade inoculums 

(Figure 10.37B), which are more expensive, may be mixed with water and applied directly onto 

seeds or as a root dip. Use of fi ne-grade inoculum through hydroseeding equipment is a recent 

application method that shows promise as a way to combine AMF with seeds as they are sown. 

Again, there is little research on AMF inoculation eff ectiveness on roadside revegetation sites. 

Verifying the Eff ectiveness of AMF Inoculation – Unlike ECM, AMF are not visible to the unaided 

eye. To verify the eff ectiveness of AMF inoculation, roots must be stained and examined under 

a microscope (Figure 10.37D). This verifi cation can often be done easily and inexpensively 

in a laboratory.

10.1.7.5 Management Considerations for Mycorrhizal Fungi

If possible, work with a specialist to help with the following:

 · Selecting appropriate mycorrhizal partners for the species and outplanting sites;

 · Determining the best sources of inoculant and evaluating their effectiveness in the fi eld 

conditions; and

 · Designing outplanting trials to evaluate seedling survival and mycorrhizal performance 

in the field, and modifying the inoculant sources if improvements are needed. 

In addition to learning how to eff ectively apply mycorrhizal fungi, some soil management 

modifi cations will be required to promote formation of mycorrhizal partnerships in the fi eld. 

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Figure 10.37 – Several commercial AMF inoculums are available and consist of fungal 

spores mixed with an inert carrier to aid in application. Coarser-textured products (A) can be 

incorporated into soil or growing media, whereas fi ner-textured products can be sprayed like 

a wettable powder (B). Tests of inoculation eff ectiveness have shown signifi cant diff erences 

between products (C). To confi rm inoculation, plant roots must be stained so that the fungal 

hyphae are visible under a microscope (D). C modifi ed from Corkidi and others (2005). 

Mycorrhizal Inoculants

Mycorrhizal 

Responsiveness (%)

1

80

100

a

b b

c

70

60

50

40

30

20

10

0

2 3 Control

A B

C D

237
Fertilization is probably the most signifi cant adjustment. Mycorrhizal fungi extend the plant’s 

root system, and extract nutrients and water from the soil. High levels of soluble fertilizers 

may inhibit their presence. In some cases, fertilizer applications can be reduced by half or 

more due to the increased nutrient uptake by mycorrhizal fungi. Fertilizer type and form is 

also important. An excessive amount of phosphorus in the fertilizer inhibits formation of the 

partnership; therefore phosphorus should be reduced. If nitrogen is applied, ammonium-N is 

better used by the plant than nitrate-N (Landis 1989). Controlled release fertilizers are preferred 

because they release small doses of nutrients gradually, compared to the more rapid nutrient 

release from traditional products. Applications of certain herbicides, pesticides, insecticides, 

fungicides, and nematicides are detrimental to mycorrhizal fungi. 

10.1.7.6 Nitrogen-Fixing Bacteria 

Nitrogen-fi xing bacteria live in nodules on plant roots and accumulate (“fi x”) nitrogen from 

the air and share it with their host plants. Unlike mycorrhizal fungi, which are found on most 

trees and plants, only certain species of plants can form symbiotic partnerships with nitrogenfi xing bacteria. 

The role of nitrogen-fi xing bacteria and their partner plants is crucial to roadside restoration. 

Because nitrogen-fi xing plants are often “pioneer” species that are the fi rst to colonize disturbed 

sites, they are ideal for revegetation or restoration projects. Nitrogen-fi xing species are usually 

outplanted in order to help restore fertility and organic matter to the project site. Nitrogenfi xing bacteria form nodules on roots of certain plants (Figure 10.38A) and accumulate nitrogen 

from the air (Figure 10.38B). While plants that form this association are sometimes called 

“nitrogen-fi xing plants”, the plant itself is not able to fi x nitrogen from the air. It is only through 

the partnership with bacteria that these plants are able to obtain atmospheric nitrogen. In this 

symbiotic partnership the bacteria give nitrogen accumulated from the atmosphere to the 

plant, and in exchange the bacteria get a site to grow and energy in the form of carbohydrates 

from the plant. Without these bacterial partnerships, plants are not able to make direct use of 

atmospheric nitrogen. 

Soil on restoration sites, however, may not contain the proper species of bacteria to form a 

symbiotic partnership with the plant. This is particularly true for compacted soils and those 

that have been removed and stockpiled. Inoculating plants ensures that “nitrogen-fi xing” 

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Figure 10.38 – Nitrogen-fi xing plants, such as legumes, have symbiotic bacteria on their roots 

(A) which can chemically “fi x” atmospheric nitrogen into forms that can be used by plants as 

fertilizer (B).

Atmospheric

Nitrogen

N N

Fertilizer

Nitrogen

Rhizobium

Bacteria

A B

238
plants form an eff ective partnership to fi x nitrogen. Therefore, use of nitrogen-fi xing plants 

can be an important part of accelerating rehabilitation of degraded land. 

Two species of nitrogen-fi xing bacteria that are important in revegetation are Rhizobium and 

Frankia. Rhizobium grow with some members of the legume family (Figure 10.39 A&B), and plants 

of the elm family. They form nodules on the roots and fi xing nitrogen for the plant. Frankia are 

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Figure 10.39 – Nitrogen-fi xing bacteria include Rhizobium that forms relationships with plants 

in the legume family including lupines (A), and clovers (B) and Frankia that forms relationships 

with other non-leguminous plants such as snowbrush ceanothus (C), and mountain-avens (D) . 

Photos A, C, & D by Tara Luna.

A B

C D

Table 10.11 – Nitrogen-fi xing bacteria and their plant hosts.

NitrogenFixing 

Bacteria

Host Plants %

Nitrogen 

Fixing 

Family Subfamily Plants Common Plant Species

Rhizobium 

spp.

Legume Caesalpinioideae 23 Redbud, honeylocust

Legume Mimosoideae 90 Mesquite, acacia

Legume Papilionoideae 97 Lupine, milkvetch, 

black locust, clover

Family Common Plant Species

Frankia spp. Birch Alder, birch

Oleaster Silverberry, buff aloberry

Myrtle Myrtle

Buckthorn Cascara, snowbrush, deerbrush

Rose Mountain mahogany, 

cliff rose, bitterbrush 239
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a diff erent kind of bacteria. Frankia partner with non-leguminous plants, such as casuarinas, 

alders, bitterbrush, and buff aloberry (Figure 10.39 C&D), and over 200 diff erent plant species, 

distributed over eight families. The species aff ected by Frankia are called “actinorhizal” plants 

(Table 10.11). 

10.1.7.7 Uses for Nitrogen-Fixing Plants in Revegetation

Only a fraction of native species are nitrogen-fi xing host plants. In the western United States, 

the most common are the lupines, vetch, bitterbrush, ceanothus, alder, and myrtle (Table 10.11). 

On nitrogen-poor sites, sowing or planting a higher proportion of these species can help a site 

to recover nitrogen fertility and organic matter (Figure 10.40A). The amount of nitrogen that 

will be fi xed on a site is related to the area of vegetative cover in nitrogen fi xing host plants, 

the productivity of the plants, and factors such as temperature and moisture. If percent cover 

of nitrogen fi xing host plants is low, then the amount of nitrogen supplied to the site will be 

correspondingly low (Figure 10.40B). Likewise, dry or cold conditions tend to result in slower 

accumulation of nitrogen. 

To determine how nitrogen-fi xing plants should be used in revegetation project, assess which 

nitrogen-fi xing host species are native to the area and consider the nitrogen fi xation rates that 

can be expected. A plant survey of reference sites will reveal which nitrogen fi xing plant host 

species are native to the area. Finding host plants on recovered reference sites can give an 

indication of whether they grow on disturbances, and consequently how much nitrogen will 

be fi xed on the site. Observing the abundance of root nodules on these plants can give some 

indication whether they are fi xing nitrogen.

Inset 10.9 – Example of Contract Specifi cations for Purchasing Mycorrhizal Inoculum

Purchase of Mycorrhizal Inoculum

The mycorrhizal inoculum must have a Statement of Claims that certifi es the 1) date 

inoculum was produced, 2) mycorrhizal fungi species present in the inoculum, 3) number of 

propagules per pound of product, and 4) the type and grade of carrier.

Product Specifi cations

Date of inoculum application will be within one year of production date.

The storage, transportation and application temperatures of the mycorrhizae shall not 

exceed 90 °F. Inoculum must consist of at least 5 species of (choose endomycorrhizal, 

ectomycorrhizal or a combination of endo and ectomycorrhizal) fungi with no one species 

making up more than 25% of the propagules. 

The inoculum will contain these species: _________________. 

The inoculum will contain __________ live propagules per pound (Typical rates for 

endomycorrhizal inoculums average around 60,000 to 100,000 propagules per pound and 

110,000,000 propagules per pound in ectomycorrhizal inoculums.)

(For applications to the soil surface only) Live propagules must be smaller than 0.3mm.

(Optional) A one ounce sample will be collected from each inoculum and sent to _______ 

laboratory for analysis using the ______ standardized test to determine the number 

of propagules.

Application of Endomycorrhizal Inoculum to Soil Surface

Endomycorrhizal inoculum will be applied at a rate of __________________ live propagules 

per acre (typical rates range from 1,000,000 to 3,600,00 live propagules per acre).

Inoculum will be applied in the same operational period as seed application. 

If inoculum is applied through a hydroseeder, it should be applied within 45 minutes of 

being mixed in the hydroseeding tank. 

Application of Mycorrhizal Fungi to Planting Holes

Mycorrhizal inoculum will be applied at a rate of ______________ live propagules 

per seedling.

240
10.1.7.8 Inoculating with Nitrogen-Fixing Bacteria

Nitrogen-fi xing nursery stock with nodulated root systems have exhibited faster early growth 

than seedlings that were not inoculated. Nursery inoculation can reduce costs in establishment 

and maintenance; a few dollars worth of inoculant applied in the nursery can replace a lot of 

purchased nitrogen fertilizer over the life of the nitrogen-fi xing plant. Faster growth early can 

also lead to faster canopy closure, which shades the soil and reduces weed establishment and 

growth. When the nitrogen-fi xing plant sheds leaves or dies, the nitrogen stored in the plant’s 

tissues is cycled to adjacent plants. Early establishment of nitrogen-fi xing plants accelerates 

natural nutrient cycling on the project sites and promotes the establishment of sustainable 

plant communities. 

It should be noted that in many cases, uninoculated seedlings may eventually form a partnership 

with some kind of Frankia or Rhizobium strain after they are outplanted. These may not be with 

optimal or highly productive bacterial partners, and it may take months or even years on highly 

disturbed sites. Until they become naturally inoculated, plants are dependent on nitrogen 

fertilizers and may become out-competed by weeds. Inoculating in the nursery ensures that 

plants form eff ective, productive partnerships in a timely fashion. 

Acquiring Nitrogen-Fixing Bacterial Inoculants – Nitrogen-fi xing bacteria are very specifi c; in 

other words, one inoculant cannot be used for all plants. On the contrary, a diff erent inoculant 

strain for each nitrogen-fi xing species is usually necessary. Superior strains can yield signifi cant 

diff erences in productivity and growth rate of the host plant; in some cases over 40% better 

growth (Schmit, 2003).

Inoculants are live nitrogen-fi xing bacteria cultures that are applied to seeds or young plants. 

Two forms of inoculant can be used: pure culture inoculant, and homemade (often called 

“crude”) inoculant. Cultured inoculant is purchased from commercial suppliers, seed banks, or 

sometimes, universities. Crude inoculant is made from nodules collected from roots of nitrogenfi xing plants of the same species to be inoculated. Whichever form is used, care should be taken 

when handling nitrogen-fi xing bacteria inoculants because they are very perishable. These soil 

bacteria live underground in moist, dark conditions with relatively stable, cool temperatures. 

Similar conditions should be maintained to ensure the viability of inoculants during storage, 

handling, and application. 

Pure culture inoculants of nitrogen-fi xing bacteria usually come in small packets of fi nely 

ground peat moss (Figure 10.41A). Some manufactured inoculants contain select strains, tested 

for forming optimally productive partnerships with their host species. Select inoculant should 

be used if it can be obtained; these contain optimal partners for the species they were matched 

for, providing a good supply of nitrogen at a low cost to the plant. Manufactured products 

usually come with application instructions; these should be followed. In general, about 100 

grams of cultured inoculant is usually suffi cient to inoculate up to 3,000 seedlings in nursery 

conditions. Because they contain living cultures of bacteria, these inoculants are perishable 

and should be kept in cool, dark conditions, such as inside a refrigerator. 

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Figure 10.40 – The accumulation of nitrogen by N-fi xating bacteria is directly related to the 

cover of nitrogen-fi xing host plants on a site. The large plants shown in this photograph are 

lupines, which are nitrogen-fi xing (A). The nitrogen-fi xing potential of 15-year-old stands 

of Ceanothus velutinus and Purshia tridentata was directly proportional to plant cover (B) 

(adapted after Busse 2000).

Nitrogen Fixed (lbs/ac/yr)

Canopy Cover (%)

20

15

10

5

0

0 20 40 60

C. velutinus

P. tridentata

A B

241
Peat-based inoculants are added to chlorine-free water to create a liquid slurry (Allowing a 

bucket of tap water to stand uncovered for 24 hours is a good way to let chlorine evaporate).

If a blender is available, using it to blend some inoculant in water is a very good practice to 

ensure the bacteria will be evenly mixed in the solution. If a blender is not available, a mortar 

can be used. Five to ten grams (about 0.2–0.4 ounce) of manufactured inoculant can inoculate 

about 500 seedlings, usually exceeding the recommended 100,000 bacteria per seedling. Once 

seedlings begin to nodulate, nodules from their roots can serve as the basis for making crude 

inoculant as described below. This way, inoculant need only be purchased once for each plant 

species grown, and thereafter, crude inoculant can be made from nodules. 

Preparing Crude Inoculant – Crude inoculant is made using nodules, the small root structures 

that house the bacteria. Each one of the nodules can house millions of bacteria. For Rhizobium, 

a brown, pink, or red color inside is usually a good indicator that the millions of bacteria in the 

nodule are actively fi xing nitrogen. For Frankia, desirable nodules will be white or yellow inside. 

Grey or green nodules should be avoided, as they are likely inactive. 

To make your own crude inoculant, select healthy, vigorous plants of the same species as the 

plants to be inoculated. Expose some of the root system of a nodulating plant in the nursery 

or fi eld (Figure 10.41B). If available, choose seedlings that were inoculated with select bacteria. 

Young roots often contain the most active nodules. Search for nodules with the proper color 

and pick them off cleanly. If possible, collect nodules from several plants. Put nodules in a 

plastic bag or container and place them in a cooler for protection from direct sunlight and 

heat. As soon as possible after collection (within a few hours), put the nodules in a blender 

with clean, chlorine-free water. About 50-100 nodules blended in a liter of water is enough to 

inoculate about 500 seedlings. This solution is a homemade liquid inoculant, ready to apply in 

the same method as cultured inoculant as described below.

Applying Inoculant – Inoculant must be applied in a timely fashion, when seedlings are just 

emerging, usually within 2 weeks of sowing. This helps ensure successful nodulation and 

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Figure 10.41 – Nitrogen-fi xing bacteria are commercially available as pure culture inoculant, 

often in a carrier (A), or can be prepared by collecting nodules off of plants from the wild (B). 

Photos by Tara Luna.

A B

Figure 10.42 – After successful 

inoculation, nitrogen-fi xing bacteria will 

multiply on the root system as plants 

grow. The arrow points to a visible 

Frankia nodule on an alnus seedling. 

Photo by Tara Luna.

242
maximizes the benefi ts of using inoculants. 

Therefore inoculant must be introduced in the 

nursery for nursery-grown plant materials, or 

introduced at the time of sowing for seeds that 

are sown directly at the fi eld site. One liter of 

liquefi ed inoculant made from either nodules 

or cultured inoculant as per the instructions 

above is diluted in more chlorine-free water. 

For 500 seedlings, about 5 liters of water is 

used. This solution is then watered into the root 

system of each seedling using a watering can. 

In the fi eld, for direct seeding applications, the 

slurry of commercial or crude inoculant can be 

added to the hydroseeder tank and mixed in 

with seed mixes. 

10.1.7.9 Management Considerations 

for Nitrogen-Fixing Inoculations

Verifying the Nitrogen-Fixing Partnership –

Allow two to six weeks for noticeable signs that 

the plant has formed a symbiotic partnership 

with nitrogen-fi xing bacteria. Signs include: 

 · Seedlings begin to grow well and are 

deep green despite the absence of 

added nitrogen fertilizer,

 · The root systems give off a faint but 

distinctive ammonia-like scent, 

 · Nodules are usually visible on the root 

system after about four to six weeks 

(Figure 10.42), and nodules are pink, 

red, or brown (for Rhizobium), or yellow 

or white (for Frankia).

Post-Planting Care – Several factors are of primary concern when using inoculants for nitrogenfi xing bacteria: 

 · Fertilization. The use of nitrogen-fixing bacterial inoculant requires some adjustments 

in fertilization. Excessive nitrogen fertilizer will inhibit formation of the partnership. 

 · Water quality. Excessive chlorine in water is detrimental to Rhizobium and Frankia. 

The water source may need to be tested and a chlorine fi lter used if excessive chlorine 

is a problem.

 · Micronutrients and soil quality. Some nutrients are necessary to facilitate nodulation, 

including calcium, potassium, molybdenum, and iron. Excessively compacted soils, 

extremes of pH or temperature also inhibit nodulation. 

10.1.7.10 Other Benefi cial Microorganisms

In nature, communities of bacteria, fungi, algae, protozoa, and other microorganisms in the soil 

make nutrients available to plants, create channels for water and air, maintain soil structure, 

and cycle nutrients and organic matter. A healthy population of soil microorganisms can also 

maintain ecological balance, preventing the onset of major problems from viruses or other 

pathogens that reside in the soil. The practice of protecting and re-establishing benefi cial 

microorganisms is a key one for revegetation. As a science, however, the use of benefi cial 

microorganisms is in its infancy. Although thousands of species of microorganisms have 

been recognized and named, the number of unknown species is estimated to be in the 

millions. Almost every time microbiologists examine a soil sample, they discover a previously 

unknown species (Margulis and others, 1997). Revegetation specialists should keep an eye on 

developments in this fi eld and see how their plants can benefi t from new insights into the roles 

of microorganisms. Conserving and utilizing healthy topsoil will also help to sustain the natural 

populations of benefi cial microorganisms. 

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Inset 10.10 – How Does Biological 

Nitrogen Fixation Work?

The symbiotic partnership between 

plants and their nitrogen-fi xing 

microsymbionts works this way: The 

bacteria live in nodules on roots of the 

plant. Each nodule contains millions 

of the bacteria that accumulate 

atmospheric nitrogen and share this 

nitrogen with the plant. In exchange, 

the plant provides energy in the form of 

carbohydrates to the bacteria. 

The bacteria must come in contact 

with the root systems early in the 

plant’s life, ideally within the fi rst 2 to 

6 weeks of growth. For nursery-grown 

materials, nitrogen-fi xing bacteria 

must be introduced in the nursery. For 

direct fi eld sowing of seed, inoculants 

should be applied as the seeds are 

being sown. 

When the “nitrogen-fi xing” plant sheds 

its leaves, dies, or dies back, the nitrogen 

stored in the plant’s tissues is cycled to 

other plants and through the ecosystem. 

This process, part of the nitrogen cycle, 

is the major source of nitrogen fertility 

in most natural ecosystems. 

243
10.1.8 TOPOGRAPHIC ENHANCEMENTS 

10.1.8.1 Introduction

Topographic enhancements are alterations to the roadside landscape designed to improve the 

growing environment for plants. Topographic enhancements should be considered when site 

resources such as topsoil, organic matter, and water are limited (See Section 5.11, Inventory Site 

Resources). It is often better to concentrate limited resources in key areas where resources can 

be most eff ective, rather than spread them across the larger project area and dilute them to the 

point of having little benefi t to reestablishing native vegetation. 

Topographic enhancement integrates three components into the roadside design – soil 

improvement, site stability, and water harvesting (Figure 10.43). Soil improvement can occur 

when limited topsoil and organic matter are strategically used to create growing areas with 

optimum rooting depth (See Section 5.3 and Section 5.5). Stable landforms are created that 

reduce surface erosion and increase slope stability (See Section 5.6 and Section 5.7). Water 

harvesting can result when local topography is modifi ed to capture runoff water and concentrate 

it in areas where it can be used by plants (See Section 5.2) (For background on water harvesting, 

see Fidelibus and Bainbridge 2006).The integration of these three components will determine 

the success of a topographic enhancement design. 

Topographic enhancement strategies must be considered during the initial planning stages 

of road design. These structures will require the input of the design engineer and cooperation 

of the project engineer, and must be built during the construction phase of the project. 

Structural changes to the topography following construction are not usually an option for 

revegetation purposes. 

There are many options for topographic enhancement. This discussion is by no means 

exhaustive, but intended to introduce the reader to a variety of structures that can be installed 

during road construction to enhance the establishment of native plants.

10.1.8.2 Contour Bench Terraces, Planting Pockets, and Microcatchments

Contour bench terraces are structures carved out of cut or fi ll slopes that capture and store 

runoff water and sediments from road surfaces, road shoulders, and the slopes above. 

If infi ltration rates of soils above the terraces are low, runoff will occur, even from low intensity 

rainfall. Contour bench terraces are designed to collect enough water to recharge soils and 

provide suffi cient water for plant growth during the summer, but also be protected from erosion 

during peak rainstorm events. Design criteria for determining the distance between terraces 

include slope gradient, rainfall intensities, and infi ltration rates. Observing erosional patterns 

on unvegetated road cuts near the project site can give an indication of approximate spacing 

for benches (See Section 5.6.8). 

Contour bench terraces can be long 

and contiguous or separate and 

discrete. For long and contiguous 

terraces, concentrated water from 

high runoff events can fl ow down 

the terraces (assuming they are not 

completely level), potentially causing 

gullies. Placing berms or “plugs” in 

the terraces at frequent intervals can 

reduce this potential.

When terraces are fi lled with growing 

media (topsoil or amended subsoil) 

and planted, they are referred to 

as planting pockets (Figure 10.44). 

Planting pockets must have adequate 

soil depth to store intercepted water 

and support establishment of planted 

seedlings. The surface of the planting 

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Figure 10.43 – Integrating soil improvement, site 

stability, and water harvesting is critical when 

designing topographic enhancement features.

Topographic Enhancement

Optimum

Vegetation

Establishment

Site

Stability

Water

Enhancement

Soil

Improvement

244
pocket should be insloped to capture water and sediment, and the face of the pocket should 

be protected from surface erosion.

Fill slope microcatchments are structures that capture runoff from outsloped road surfaces and 

compacted shoulders into terraces and berms where it can be used for plant growth (Figure 

10.45). Microcatchments include a storage basin and berm. Berms are typically 4- to 8-inch 

high obstacles placed on the contour. They are formed from soil or woody debris (logs), or 

manufactured products such as straw waddles (Figure 10.45) or compost berms. Manufactured 

products and woody debris are “keyed” (partially buried) into the soil surface to prevent water 

from eroding under the structure. Compost berms are continuous mounds of compost that 

can slow water and fi lter sediments. Seedlings can be planted on, or immediately above, berms 

or obstacles to access captured water. Unless species that propagate vegetatively are used in 

these structures (See Section 10.2.2), care must be taken to avoid planting where sediment will 

bury the seedling. The storage basin, created by terraces or berms, can be improved for plant 

growth with soil tillage and incorporation of soil amendments. 

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Figure 10.45 – Fill slope microcatchments take advantage of the low infi ltration rates of 

compacted fi ll slopes (A) by capturing the runoff from road drainage at the bottom of the fi ll into 

topsoil or amended subsoil favorable for plant 

growth (B). The extra water from these surfaces 

can support trees and shrubs. Straw waddles, as 

shown in the picture on the right, can be used in 

fi ll slope microcatchments to collect water and 

sediment. Straw waddles must be installed on the 

contour and keyed into the soil to be eff ective.

A

B

Figure 10.44 – Planting pockets collect and store runoff water from areas directly upslope 

during rainstorms (A). Water and sediments collect in the back slope of the pocket (B). Moisture 

fi lls the soil and moves into fractured bedrock (C) where roots have penetrated. The face of 

the planting pocket is protected by mulch or 

erosion cloth (D). The photograph on the right was 

taken looking down on a planting pocket after a 

rainstorm. The back slope has ponded water and 

collected sediments from the surface above.

A

B

D

C

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10.1.8.3 Runoff Strips and Constructed Wetlands

Runoff strips are catchment structures constructed in areas where intermittent concentrated 

road drainage occurs. These are typically at the outlets of culverts or in road drainage dips. 

Runoff strips capture concentrated runoff into small ponds or catchment basins. These areas 

can be planted with riparian species, such as willows (Salix spp).and cottonwoods (Populus spp.), 

or wetland species, such as rushes (Juncus spp).and sedges (Carex spp.). Runoff strips are placed 

in draws or concave topography and are composed of engineered impoundment barriers, 

using riprap, logs, or gabion baskets, that store water from runoff events. The barrier must have 

a spillway (a low point in the structure) and be keyed into the sides to assure that concentrated 

water does not erode around its sides. Where runoff strips are on gentle gradients, constructed 

wetlands may possibly be developed (Figure 10.46). 

10.1.8.4 Planting Islands

Planting islands are used where deep-rooted tree and shrub species are desired, but topsoil, 

soil amendments, or soil depth are limiting. They are designed into such revegetation projects 

as obliterated roads, view corridors, waste areas, and other highly disturbed sites. The strategy 

behind planting islands is to create an ideal growing environment for tree and shrub seedlings 

that replicates the natural patterns or features observed in the surrounding landscape and 

plant communities (Figure 10.47).

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Figure 10.46 – Constructed wetlands 

capture water from roadside runoff 

and fi lter sediments before water enters 

perennial streams. Constructed wetlands 

can create favorable habitat for unique 

fl ora and fauna.

Figure 10.47 – Most planting islands 

are designed to mimic the natural 

surrounding environment of the project 

site. In this photograph, seedlings 

were planted in clumps to mimic the 

small islands of trees that grew in 

this geographic area. The inter-island 

areas were planted with lower growing 

grasses, forbs, and shrubs.

246
Islands can be created by excavating an appropriate area to a depth of several feet and 

backfi lling with either topsoil or compost-amended material (Figure 10.48). Alternatively, 

compost and other soil amendments (including lime and fertilizers) can be spread over 

planting islands at the depth needed to amend the soil profi le and mixed thoroughly through 

the islands with an excavator or backhoe. Soil compaction must be avoided in these operations 

or during any subsequent operation. After planting, mulch can be applied across the surface 

of the entire island. 

In Figure 10.48, compost is mixed to a depth of 3 feet by an excavator in irregular shaped 

planting islands. The islands are planted with conifers and 3 inches of mulch are applied to 

entire islands to keep them free of competing vegetation. The layout of planting islands should 

be designed with a vision of how the vegetation will appear once established, and should be 

based on recovered and undisturbed reference sites. Planting islands will generally occupy less 

than a quarter to a third of the entire site, leaving the remainder as “inter-island.” The interislands will be much less productive than the planting islands. Grass and forb plant communities 

are therefore more suited to these areas.

10.1.8.5 Biotechnical Engineering Structures

Topographic enhancement also includes many biotechnical engineering structures, such as 

vegetated retaining walls, brush layers, and live pole drains. Incorporating soil improvement 

strategies into these structures will stabilize the soil and capture runoff water, making 

them very suitable to the establishment of a range of native vegetation (See Section 10.3.3 

and Section 10.3.4). 

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Figure 10.48 – Illustration of a typical cross-section of a planting island where soil depth is 

enhanced for tree establishment. Inter-island areas are planted to shrubs and grasses.

Inter-Island

Unamended Fill

Inter-Island

Unamended Fill

Planting Island

Compost Amended

Mulch

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10.2 OBTAINING PLANT MATERIALS

Obtaining the appropriate species and stocktype for a revegetation project takes good 

planning and lead time. To obtain genetically adapted materials often requires the collection 

of plant materials near or in the general geographic area of the project site. This requires 

collecting plant materials several years in advance of project implementation. The group of 

implementation guides in the following section focuses on three types of plant materials – 

seeds, cuttings, and plants. Section 10.2.1, Collecting Wild Seeds, covers how to determine the 

amount of wild seed to collect, wild seed collection methods, cleaning techniques, storage 

conditions, and quality testing. Methods for collecting the stems of willows and cottonwoods 

in the wild (as well as several other native species that propagate vegetatively) are discussed in 

Section 10.2.2, Collecting Wild Cuttings. Salvaging plants from the wild and replanting them on 

project sites is discussed in Section 10.2.3, Collecting Wild Plants.

For most projects, the collection of wild seeds, cuttings, or plants is not suffi cient to meet project 

objectives. To increase plant materials, wild collections must be sent to native plant nurseries 

for propagation. Section 10.2.4, Nursery Seed Production, outlines the basic steps necessary to 

work with nurseries in establishing seed production beds for increasing seed banks. Producing 

large quantities of cutting material of willow and cottonwood species can be accomplished by 

establishing stooling beds from wild collections at nurseries. This is covered in Section 10.2.5, 

Nursery Cutting Production. Section 10.2.6, Nursery Plant Production, covers how to work with 

seedling nurseries to obtain high quality plants.

10.2.1 COLLECTING WILD SEEDS 

10.2.1.1 Introduction

Wild seeds are collected from native stands of grasses, forbs, shrubs, trees, and wetland plants 

found in or near project sites. The primary objective for wild seed collection is to obtain sourceidentifi ed seeds for starting nursery grown plants (See Section 10.2.6), nursery grown seeds 

(See Section 10.2.4), and/or occasionally to sow directly on a disturbed site. Since seed and 

seedling propagation hinges on availability of wild seeds, collection is one of the fi rst major 

tasks of a revegetation plan. Depending on the purpose, the lead-time for collecting wild seeds 

might be up to 3 to 4 years before sowing or planting the project site (Figure 10.49). 

Grass and forb species are usually seeded directly onto disturbed sites. In order to obtain 

enough seeds for direct seeding, wild seed collections are usually “increased” in nursery 

production (See Section 10.2.4). Trees and shrubs, on the other hand, are not typically seeded 

across disturbed sites. Wild seed collections for these species are sent to nurseries for seedling 

propagation, then outplanted. Seeds from wetland genera, such as sedges (Carex spp).and 

rushes (Juncus spp).are often collected for both seed and seedling production purposes.

Revegetation plans are seldom fi nalized before wild seeds are collected. At a minimum, 

planning should have identifi ed revegetation units, described reference areas, determined 

species to propagate, and completed a survey of the construction site to determine the amount 

of area to be revegetated. The quantity and location of wild seed collection is based on these 

early surveys. 

Collecting wild seeds can be expensive. Multiple collection trips are often needed to monitor 

and collect each species. Each species has a small ripening window, and most species do 

not ripen at the same time. In addition, many species do not consistently produce seeds 

from year to year, requiring multiple year collections. Working around these complexities to 

obtain adequate supplies of wild seeds requires excellent planning and administration of seed 

collection and cleaning contracts. 

Before collecting wild seeds or setting up collection contracts, it is worth the eff ort to contact 

Forest Service district or BLM area offi ces fi rst to see if seeds are already available for your 

project. Often these local agencies will have seeds in storage for many of the species growing 

near the project area, especially species used for reforestation.

10.2.1.2 Develop Timeline

Wild seed collection should be one of the fi rst tasks to consider when beginning revegetation 

planning because other tasks, such as seed and seedling propagation contracts, cannot be 

conducted without this plant material. Up to 3 or 4 years are often necessary in order to locate, 

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collect, clean, and test wild seeds, and still allow the nursery or seed producer enough lead 

time for plant and seed production (Figure 10.49). 

The seed collection contract is awarded early in the spring to give the contractor enough time 

to locate and assess the collection areas. Seeds are monitored from June through August and 

collected when ripe. Wild seed harvests are cleaned from September through October and 

then tested. Results from seed testing facilities are returned by December. Seeds designated 

for seedling propagation must be sent immediately to the nursery for preparation for sowing 

in early winter. If seed propagation is the objective, seeds are stored until the following summer 

and sent to seed producers for a late summer sowing.

10.2.1.3 Determine Wild Seed Needs for Seed Production

Wild seed collection and the nursery seed increase contracts are often developed simultaneously 

because the information needed for wild seed collection is based on the expected seed yields 

of the seed increase contract. This section describes how to calculate the amount of wild seeds 

to collect based on the amount of seeds expected from a nursery seed producer. 

The amount of uncleaned wild seeds to collect for seed propagation contracts requires the 

following information (used in calculations in Figure 10.50):

 · Seed needs,

 · Years in seed production,

 · Sowing rates,

 · Annual seed yields, and

 · “Cleaned-to-rough cleaned” seed ratio.

Seed Needs – The total seeds needed for each species on a revegetation project is based on 

the total planned revegetation acreage, seedlot characteristics (germination, purity, seeds per 

pound), site limitations (how well seeds will survive), and the desired seedling densities after 

seeds have germinated. The reader is referred to Section 10.2.4.3 for methods to calculate how 

many seeds are needed for each species in a revegetation project.

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Figure 10.49 – Wild seed collection is one of the fi rst contracts developed during planning. 

Seeds are needed to implement seed and seedling propagation contracts. A lead-time of 2 to 4 

years is typically needed for wild seed collection.

Determine seed needs

Wild Seed Collection

Tasks

Year

Locate collection sites

Develop & award contract

Pick seed

Clean seed

Test

-4 -2 - -3 1 0

Seed Production Road Construction Sow

249
Years in Seed Production – Every species has its own seed production characteristics. For 

instance, species such as blue wildrye (Elymus glaucus) and California brome (Bromus carinatus) 

produce high seed quantities the fi rst and second year, then level off or decline in years three 

and four. Species such as fescues (Festuca spp).and Junegrass (Koeleria spp).yield few seeds in 

the fi rst year, but seed harvest levels increase to full production in the second or third year. For 

these species, a minimum of two years must be scheduled for seed production. Table 10.14 in 

Section 10.2.4 shows fi rst- and second-year yields for some commonly produced species. 

Since seeds can be stored for many years, seed production does not have to occur all in one 

year. For projects that have several years lead time, maintaining production fi elds gives the 

revegetation specialist more fl exibility. By spreading the seed production over several years, the 

acreage in production and the amount of wild seed to collect can be cut in half. For example, 

if 800 lb California brome (Bromus carinatus) seeds for a revegetation project are needed and 

there are two production years to produce it in, the amount of seeds to produce per year would 

be 400 lb. Since half the acreage would be sown, the amount of wild seed to collect would be 

cut in half, from 10 pounds to 5 pounds.

Sowing Rates – All growers require a minimum amount of clean, wild seeds to produce 

a given quantity of nursery-grown seeds. While these rates diff er somewhat between seed 

producers, general sowing rates for commonly propagated species are shown in Table 10.14 in 

Section 10.2.4. 

Annual Seed Production Yields – The amount of seeds that are produced annually varies by 

species, geographic location of the fi elds, weather conditions, and experience of the seed 

producer. Knowing what yields can be expected from seed producers will determine how 

many acres will be under production and the amount of wild seeds needed to start the crop. 

Average seed yields for some species are presented in Table 10.14 in Section 10.2.4. 

Cleaned-to-Rough Cleaned Seed Ratio – Seed collection from the wild will include stems, 

chaff , and fl ower parts (Figure 10.51). This material should be cleaned as much as possible by 

the seed collectors before it is sent to the seed extractory for fi nal cleaning. The amount of nonseed collected can be a substantial part of the wild seed collection weight. “Cleaned to rough 

cleaned” seed ratios (Table 10.12) can help calculate the extra weight of seeds to collect in the 

wild to compensate for seed cleaning. Dividing the desired amount of cleaned seeds by this 

Roadside ratio will yield the amount of wild seed that needs to be collected. Revegetation

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Figure 10.50 – The quantity of wild seeds to collect can be determined from this spreadsheet. 

Pearly everlasting (Anaphalis margaritacea) is used in this example.

A Seed production needs 22 lbs From seed needs plan (See Section 10.2.4.3)

H (100 / G) * F 0.67 lbs Rough weight of seeds to collect

G 33 % Estimated “Cleaned to rough cleaned”

seed ratio

F 0.22 lbs Cleaned wild seeds that seed producer 

needs to sow E * C =

E (A/B) / D 0.22 ac Area seed producer needs to sow

D 50 lbs/ac/yr

See Table 10.14 in Section 10.2.4.

If spanning more than one year, average 

the expected first and second year yields

Annual seed yields

C 1 lbs/ac See Table 10.14 in Section 10.2.4 or

discuss with seed producer Sowing rates

B 2 yrs Seed production can span several years 

depending on lead time of project. Years in production

250
10.2.1.4 Determine Seed Needs for Seedling Production

The quantity of wild seeds to collect for propagating seedlings at plant nurseries will be based 

on an estimate of 1) quantity of seedlings needed, 2) % seed germination, 3) % seed purity, 

4) seeds per pound, and 5) nursery factor. An estimate of germination, purity, and seeds per 

pound can be obtained through published sources, seed inventories, or from seed extractory 

managers. The nursery factor is a prediction of the percentage of viable seeds that will actually 

become “shippable” seedlings. Each nursery has developed a set of factors based on culturing 

experience and practices. Nursery managers should supply nursery factors for each species or 

information on the amount of seeds to collect to meet the seedling order. Nursery factors are 

often less than 50%.

Using the following equation, the amount of wild seed to collect can be estimated:

 Wild seed to collect = quantity of seedlings needed

 (% germ/100 * % purity/100 * seeds/pound * nursery factor/100)

10.2.1.5 Locate Plants in the Wild

Collection areas are located in the fi eld during the vegetation analysis phase (See Section 

6.2). General collection locations can be established by the revegetation specialist under the 

direction of a botanist familiar with the local vegetation. Contracts often require seed collectors 

Table 10.12 – Typical ranges of “cleaned-to-rough cleaned” seed ratios. To obtain the amounts 

of “rough” seeds to collect, divide the amount of cleaned seeds needed by the “cleaned-to-rough 

cleaned” ratio. For example, if 5 lb cleaned seeds of prairie Junegrass (Koeleria macrantha) are 

needed, a minimum of 12.5 lb rough cleaned seeds must be collected (5/40*100=12.5) (Chart 

based on R6 Forest Service seed collections data.)

Common Name Scientific name

Bluebunch Wheatgrass Pseudoroegneria spicata

Idaho Fescue Festuca idahoensis

Prairie Junegrass Koelaria macrantha

Squirreltail Elymus elymoides

Yarrow Achillea spp.

Sandberg Bluegrass Poa secunda

Blue Wildrye Elymus glaucus

25 to 33

33 to 50

20 to 40

20 to 25

20 to 25

33 to 40

50 to 65

Cleaned-to-Rough

Cleaned Ratio

Figure 10.51 – Field collected seeds 

include stems, chaff , fl ower parts, and 

seed attachments. Species such as 

cutleaf silverpuff s (Microseris laciniata) 

have a low “clean-to-rough” seed ratio 

and must be sent to a seed extractory 

for cleaning prior to sending to 

seed producers.

251
to identify individual collection areas for approval prior to collection. Since seed collection can 

start in late spring for some species, collection site location must be completed by this time. 

Collection areas for each species should not occur in one location, but represent a crosssection of populations in the general area of the project. A minimum of fi ve collection areas, 

at least a mile apart, should be identifi ed for each species. This ensures that a range of genetic 

characteristics is represented in each seedlot. While some populations will be located in 

the project area, most areas will have to be found in adjacent areas. When seed collection 

is conducted outside of the project area or agency administered lands, permission must be 

obtained from the landowner or manager.

Collection sites must be free of any plants listed as noxious weeds by the Oregon Department 

of Agriculture (“A and B” weed lists) because of the potential of seed contamination. Once 

located, the collection sites should be marked with fl agging at a point easily visible from the 

road used to access the site. The fl agging should have a written description that includes the 

GPS location (including elevation and UTM [Universal Transverse Mercator] coordinates) or 

a compass bearing and approximate distance in feet from the access road to the collection 

site. Each site should be approved by the revegetation specialist/botanist. Locations will be 

numbered sequentially and the location placed on 7.5° topographic maps and each collection 

site must be described and documented in the fi eld notes. 

10.2.1.6 Collect Seeds

Only viable seeds that are visually sound and suffi ciently mature should be collected. Seeds are 

considered sound when the embryo is developing normally and there is no evidence of insect, 

disease, climatic, or other types of damage. Seed maturity in plants with fl eshy fruits (many 

shrub and some tree species) often corresponds with changes in color (e.g., color changes from 

green to red, blue, purple, or white), taste (higher in sugars when mature), or hardness (fruit 

softens with maturity). Wind-dispersed seeds (which include many of the conifer species) usually 

change from green to brown when ripe. For grass species, seed maturity can be determined 

by how seeds respond to being squeezed (Inset 10.11). Since seed ripeness is infl uenced by the 

local weather and microclimate, determining seed ripeness often requires several monitoring 

trips to the fi eld prior to collection.

Seed collection techniques are tailored to the species being collected. Grass and forb species, 

for instance, can be hand-harvested by stripping or clipping stems just below the seed heads 

and placing them in collection bags or containers. Collection bags should be made of materials 

that allow airfl ow, such as paper or fi ne mesh. Plastic bags or plastic containers should not be 

used. Other methods of collecting grass and forb seeds include mechanical fl ails and vacuums. 

While these methods can increase seed harvesting rates signifi cantly, they must be done on 

nearly pure stands of a single species to avoid contaminating the seedlot with more than one 

species. Some forbs, such as lupine (Lupinus spp.), have indeterminate infl orescence, which 

means they continuously bloom, starting from the bottom of the fl ower head and progressing 

to the top (Figure 10.52). These species present a problem in seed collection because seeds 

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Inset 10.11 – Stages of Grass Seed Maturity

For grasses, the stages of seed ripening can be determined by squeezing a seed 

between the thumb and forefi nger. The stage of seed maturity is broadly defi ned by the 

following response: 

Milk stage. A milky substance is secreted, indicating an immature seed lacking viability. 

Soft-dough stage. Seed has a doughy texture, indicating it will have low germination and 

viability if collected.

Hard-dough stage. No excretion of dough or milky substance when squeezed. Seeds are 

collected at this stage. Seeds can be collected at the transition between soft-dough and 

hard-dough stages. If collection occurs between these stages, seeds should not be stripped 

from the plant. Instead, seed heads should be cut and placed in collection bags where seeds 

will continue to mature.

Mature. Seeds in this stage are usually too hard to bite. Collection should begin immediately 

because seeds can dislodge from the stem at any time. 

252
ripen continuously through the growing season. Seeds from these species are often obtained 

by making multiple trips to the fi eld and collecting seeds from the lower portions of the stem 

without disturbing the fl owers or immature seeds above. 

Seeds of many shrub species are often collected by holding a bag or tray under the plant and 

shaking the plant or fl ailing the branches with a stick or tennis racket. While the seeds of some 

shrub species ripen and remain on the seed head, others, such as Ceanothus spp., shatter when 

they ripen and must be collected as soon as they ripen. Since multiple collection trips can be 

expensive, an alternative approach is to enclose the seed head of each plant in a mesh or paper 

bag before the seeds have begun to ripen. At the end of the season, ripened seeds will have 

dispersed into the bags, which can be easily collected. The seed collection contractor should 

specify the methods that will be used for collection.

Seeds should be collected in approximately equal quantities from approved collection areas 

(See Section 10.2.1.5). To ensure adequate genetic representation, collect from a large number of 

widely spaced or unrelated parent plants per area (over 50 is optimal). To preserve populations, 

no more than 50% of the seed crop at each site should be collected in a year. Seeds or seed 

bearing fruits should not be collected from the ground. 

Each seed collection bag or container must be clearly identifi ed in the fi eld with the 

following information:

 · Species (scientifi c name),

 · Forest or BLM district,

 · District or BLM resource area,

 · Legal description,

 · Date of collection,

 · Name of collector,

 · Number of populations collected,

 · Elevation, and

 · Road project name.

The Forest Reproductive Material Identification Tag is an excellent way to capture this 

information (Figure 10.53). These are often available at Forest Service district offi ces or seed 

extractories. To assure the identity of the seedlot in case the tag is accidentally removed during 

handling or shipping, it is a good idea to duplicate the tag and place it into the collection bag. 

Field collections must be grouped into seedlots prior to sending these collections to the seed 

extractory for cleaning. Individual collections within a species are only maintained as separate 

seedlots if the objective is genetic testing or research. The expense of cleaning, packaging, and 

keeping records of a multitude of collections outweighs the necessity of storing them separately. 

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Figure 10.52 – Species such as lupine 

(Lupinus spp).have indeterminate 

infl orescence bloom and set seeds all 

summer. Seeds ripen fi rst at the bottom 

of the stem and continue to ripen up the 

stalk as the season progresses.

253
The information displayed on the seed tag can be used to identify or name a seedlot. Each 

seedlot is identifi ed by a seedlot identifi cation code constructed in the following manner:

Species - Forest - Seed Zone - Elevation - Project Name - Collection Year 

Species – The species short code can be obtained from the Plants Database on the National 

Resource Conservation Service website (http://plants.usda.gov/index.html).

Forest or BLM District Offi ce – This is a numerical number assigned to each forest or BLM 

district offi ce.

Seed Zone or Breeding Zone – For conifer and many native species, seed zones and breeding 

zones are geographic areas that have been identifi ed by geneticists. Consult with the local 

reforestation, botanist, or area geneticist for seed zone and breeding zone maps. 

Elevation – Elevation is generally listed as a range and abbreviated for conifer and many native 

species (For example, a 4,000 to 5,000 elevation band is listed as 4,050).

Project Name – The highway or revegetation project name is usually abbreviated.

Collection Year – The year in which the seeds were collected is abbreviated.

Certifi cation – Certifi cation codes apply to conifer tree species and are used to diff erentiate 

what is known about the parentage of the seeds. For example, codes pertain to whether the 

seeds were collected from the wild, seed collection areas, seed orchards, or if seeds are from 

tested material.

For example, the seedlot code, ARNE-10-502-2030-Elk-04, identifi es a pinemat manzanita 

(Arctostaphylos nevadensis) seed source, collected on the Rogue River National Forest in seed 

zone 502 in an elevation range of 2,000 to 3,000 ft. Seeds were collected for the Elk Creek Road 

project in 2004. 

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Figure 10.53 – A Forest Reproductive Materials Identifi cation Tag should be completed and 

attached to each collection bag sent to the seed extractory. A copy should also be placed inside 

the bag.

FOREST REPRODUCTIVE MATERIAL

IDENTIFICATION TAG

U.S.D.A. FOREST SERVICE

1) Identification Code:

(Feet above sea level)

(Person filling out tag)

2) Number of Trees 3) Ranger District 4) Elevation

4) Tree Numbers:

Species Forest BZ/Seed Zone Type Coll. Elev. Band Year Cert.

(TI Collections: affix bar code tag if available)

7) Accession No. 8) Plant Association

9) Alpha Code

10) Collection Date 11) Signature

6) Area of Collection

T.

/

/ /

R. S.

Oregon State University Seed 

Laboratory

Corvallis, OR 97331-3801

Telephone: 541.737.4464

Washington State Department of 

Agriculture

21 North 1st Avenue, Suite 203

Yakima, WA 98902

Telephone: 509.225.2630

Idaho State Department of Agriculture

3340 Kellogg Lane

Boise, ID 83712

Telephone: 208.332.8630

Inset 10.12 – State Certifi ed Seed Testing Laboratories

254
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Inset 10.13 – Seed Tests

(modifi ed from Tanaka 1984)

Seed testing is used to evaluate seedlot quality and provide information for determining 

sowing rates for seed and seedling production. Methods used for seed testing are based 

on rules of the Association of Offi cial Seed Analysts (AOSA). A number of tests are normally 

conducted on each seedlot to evaluate physical and biological seed characteristics. 

Physical Characteristics

Purity. Purity tests are used to determine the percentage by weight of four components: 

1) pure seeds of the desired species, 2) seeds of other species, 3) weed seeds, 4) inert matter, 

such as stems, chaff , scales, and small stones. Graminoid seeds with more than 10% to 

15% inert matter will be diffi cult to apply through a rotary seeder or rangeland drill. Purity 

tests should verify the seedlot contains no “prohibited” noxious weed seeds and meets or 

exceeds standards for “restricted” or “other weed seeds” according to state standards for 

Certifi ed Seed. Because each state has diff erent lists of prohibited and restricted noxious 

weeds, it is important to request an “All-States Noxious Weed Exam.” While not prohibited 

or restricted by the State, some aggressive non-natives found through seed testing may still 

pose a threat to native plant communities.

Moisture content. Seed moisture content for most species is determined by oven-drying. 

Seed samples are weighed and heated at 105 °C (221 °F) for 16 hours, then weighed again. 

Seed moisture is expressed as the percentage of the weight of the water lost over oven-dry 

weight. Electronic moisture meters are also frequently used, but are not as accurate as the 

oven-drying method. They give rapid measurements when checking moisture in a large 

number of seedlots. 

Moisture tests are important for determining the storability of seeds. Typically, seed 

moistures for long-term storage should be less than 10%.

Seeds per pound. Seeds per pound is the weight of a given number of seeds of the desired 

species, and does not include seeds of other species or weed seeds. The method weighs 100 

seeds of ten random samples and converts the values to number of seeds per pound.

Biological Characteristics

Germination. A germination test conducted in a controlled environment is the most reliable 

method for testing seeds. At least 400 seeds from the pure-seed component of the purity 

test are used in the test. Depending on the species, the seeds are usually divided into four 

replicates of 100 seeds each and chilled (stratifi ed) for a pre-determined period and placed 

on trays in controlled germination chambers. At 7-day intervals, the number of seeds that 

have germinated (when all essential structures appear normal) are counted (AOSA 2002). 

Tetrazolium staining. Although controlled-environment germination tests are reliable, they 

are also time-consuming, particularly for those species requiring chilling. A rapid method of 

estimating viability is tetrazolium (TZ) staining. This test is preferred if results are needed 

immediately, or if species to be tested have unknown chilling or germination requirements, 

which is often typical of many native species (Rauch 2006). The TZ test requires seeds to 

be immersed in 2,3,5-triphenyl tetrazolium chloride. Living cells stain red as the chemical 

is reduced by dehydrogenase enzymes to form a stable red triphenyl formazan, which is 

insoluble in water. Seeds are cut and the embryos are that are red-stained are counted as 

viable seeds. This test is very useful for native species that produce seeds that are dormant 

and will not germinate without after-ripening (that is, seeds placed in an environment 

where they will continue to ripen) or without special germination enhancement treatments 

(stratifi cation, scarifi cation, gibberellic acid, and so on). In these cases, germination 

tests usually report out lower viability rates than actually exist. Since TZ tests measure 

the percentage of live embryos, they typically give a better indication of potential 

germination rates.

X-ray. At least 400 seeds, divided into four replicates of 100, are x-rayed and evaluated for 

presence of mature embryos, insect damage, fi lled seeds, damaged seeds, and other seed 

characteristics that might aff ect germination. X-raying is a quick test, but not as accurate as 

germination or TZ tests. 255
10.2.1.7 Clean and Test Seeds

Wild seed collections must be cleaned to a standard that can be uniformly applied through 

seed sowing equipment for seedling production or seed increase. Seed extractories have 

the experience and equipment to clean wild seeds of most species. Seed cleaning is typically 

completed in two to three steps: 1) removing seeds from cones or seedpods (conifer species and 

some hardwood tree and shrub species), 2) detaching structures from seeds, and 3) removing all 

non-seed materials from collections. Removing seeds from most conifer cones involves using 

tumbling equipment to allow seeds to separate from scales. Some conifer species and many 

shrub and hardwood species require specialized equipment to break open the seedpod without 

damaging the seeds. Detaching seed structures involves the mechanical removal of awns 

(grasses), wings (conifers), and fl eshy structures (shrubs). Once seed structures are detached, 

all non-seed materials, including stems and chaff , can be removed from the collections, leaving 

only pure seeds. Seed extractories will dry, package, and store seeds, as well as test seeds onsite or send seeds to a testing facility. It must be noted that seed extractories cannot improve a 

poorly collected seedlot. For example, seed extractories cannot remove weed seeds, damaged 

seeds, or immature seeds from a collection, nor separate seeds from diff erent crop species 

mixed in a seedlot. Prior to collecting wild seeds, it is important to contact the seed extractory 

manager to discuss which species will be cleaned. Seed extractory managers are great sources 

of information on collection and care of a variety of native species seeds.

Cleaned seeds should be tested for germination, purity, seeds per pound, and presence 

of noxious weeds (Inset 10.13) by an approved seed testing laboratory (Inset 10.12). Testing 

requires representative samples be collected from each seedlot. Seeds are usually stored in 

large sealed drums or bags. Seeds should be sampled with probes that reach to all parts of the 

storage container. If there are multiple containers per seedlot, samples from each container 

should be drawn in proportion to the size of the container. Since the amount of seeds needed 

for testing may vary by species and laboratory, seed testing facilities should be contacted prior 

to submitting samples for special instructions.

Seed viability usually decreases with time in storage. Seed testing should be conducted every 

few years, or at least the year before it is sown, to obtain the most accurate germination rates. 

Copies of seed tests should be retained in contract fi les and on seed inventories. 

10.2.2 COLLECTING WILD CUTTINGS 

10.2.2.1 Introduction

Using cuttings can be a viable alternative to planting seedlings or sowing seeds to reestablish 

native vegetation. Vegetative material is collected from stems, roots, or other parts of donor 

plants and directly planted on the project site or sent to a nursery to produce rooted cuttings. 

The potential to produce roots from vegetative cuttings varies by species – from easy to 

propagate to extremely diffi cult. The most common species propagated from vegetative 

cuttings are shrubs and some trees. Many deciduous species that grow well in riparian settings, 

such as willows (Salix spp).and cottonwoods (Populus spp.), have a high success rate when 

propagated from cuttings. Most temperate evergreen trees and shrubs, however, only root 

under very controlled environments with specialized propagation techniques. 

The intent of this section is to provide the reader with a greater understanding of how to select 

and collect cuttings in the wild. The primary focus will be on the species in the genera Salix

and Populus, because these are these are most frequently used for direct sticking. Most other 

temperate tree and shrub species must be sent to the nursery for the production of rooted 

cuttings before they are installed on project sites (In tropical and subtropical areas, a wider 

variety of species can be collected as wild cuttings).If temperate species other than willow and 

cottonwood are considered for propagation, nurseries should be contacted to determine the 

best methods for selecting, cutting, and handling the material. 

Cuttings can be obtained from wild collections or from cultivated stands of donor plants, called 

stooling beds. Stooling beds are established at nurseries or other agricultural facilities from 

wild collections. In this section, we will focus on how to obtain cuttings from wild locations 

and leave the discussion of producing cuttings from stooling beds to Section 10.2.5, Nursery 

Cutting Production. 

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Wild cuttings are used in revegetation projects when 1) seeds or seedlings are diffi cult to 

obtain, 2) seeds germinate poorly in the nursery, or 3) cuttings are needed for biotechnical 

engineering objectives. Seed yields can be low for many species due to a variety of reasons, 

including poor pollination, disease, and insect damage. Some species, such as pinemat 

manzanita (Arctostaphylos nevadensis) and Pacifi c yew (Taxus brevifolia), produce seeds which 

can be very diffi cult to germinate in nursery environments. Other species, which include many 

tree species, produce seeds on an irregular basis; there may be many years between seed crops. 

Some seeds are diffi cult to collect either because they are inaccessible (in the upper portions of 

trees) or the window of seed collection is very narrow (e.g., Ceanothus spp.). For these species, 

starting plants in the nursery from rooted cuttings may be the only viable and economical 

alternative (See Section 10.2.6, Nursery Plant Production). Another important use of cuttings is 

in biotechnical engineering projects. These projects combine the physical strength of cuttings 

with root strength of establishing plants to increase surface and slope stability (See Section 

10.3.3, Installing Cuttings). 

When considering the use of cuttings over seeds or seedlings, the benefi ts must outweigh 

the potential limitations. Some factors that can limit the successful establishment of cutting 

material are the accessibility and availability of donor plants, how well the material roots 

(rooting potential), and how well the material survives once it has rooted. A common oversight 

when working with cuttings is forgetting that this material is alive and subsequently handling 

the material poorly. Another oversight is collecting cuttings outside of dormancy, when 

plants are actively growing. Neglecting either of these facts often leads to failed revegetation 

projects. This implementation guide covers the major factors that are important to consider 

when working with wild cuttings.

10.2.2.2 Develop Timeline

Locating cutting areas in the fi eld might seem like a simple task, but it can be quite diffi cult 

when you are faced with such realities as land ownership, accessibility of the cutting areas 

to roads, winter weather conditions, and poor quality of plant materials. For these reasons, a 

lead-time of several years should be considered for projects requiring large quantities of wild 

cuttings (Figure 10.54). On large projects, suffi cient lead-time allows for the location of potential 

collection sites and testing of the rooting potential of cutting material. If cuttings are used 

to propagate stooling beds (See Section 10.2.5), which are recommended for large projects, 

cuttings need to be collected at least 2 years or more before cuttings are installed on a project 

site. If the material is to be used to produce rooted cuttings at a nursery, the material should be 

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Figure 10.54 – Collecting wild cuttings requires a lead-time of several years depending on 

whether it is used to propagate stooling beds, rooted cuttings, or direction installation.

Determine cutting needs

Wild Cutting Collection Timeline

Tasks

Year

Test materials

Road Construction

Establish stooling beds

Collect for direct installation

Install cuttings or rooted cuttings

Propagate rooted cuttings

Collect for propagation

Locate cutting areas

-3 -2 1 1 0-

257
collected at least a year prior to installation. When the materials are cut for direct installation on 

a project site, the cuttings will be made in the fall through winter prior to planting. 

10.2.2.3 Locate Cutting Areas

The vegetation assessment during the planning phase (See Chapter 6) is an opportunity to 

locate potential sources of cuttings. During this fi eld survey, cutting sites are mapped and 

assessed for the following characteristics:

Proximity and Accessibility – Good sources for cuttings are not always found within the project 

site, so it is necessary to survey large areas. Sometimes good collection sites are miles away 

from the project, which can substantially increase costs. However, the benefi ts of collecting 

quality plant materials far outweigh the additional transportation costs. The large size and 

weight of cutting materials often limits collections to areas adjacent to and accessible by roads. 

Poor road conditions during the winter months, when cuttings are most likely to be collected, 

should be considered in site selection, because of the potential of being closed by snow or 

winter road damage. It is often possible to collect quality cutting material within the right-ofway clearance, which is identifi ed during the vegetation assessment.

Ownership – Some of the best collection sites may be on private lands. Always obtain 

permission from the landowner prior to collecting. Cutting from areas located on federal, state, 

and local government managed lands must be coordinated through these agencies. Observe 

collection standards for size and quantity dictated by the landowners.

Viability – The quality of the cutting material is an important criteria for determining the 

suitability of a collection site. Determining the viability of the collection material should be 

completed prior to selecting the collection site (See Section 10.2.2.4).

Genetic Considerations – It is important to determine if the species to be collected is 

monoecious (male and female reproductive parts on the same plant) or dioecious (male and 

female reproductive parts on diff erent plants). If the species is dioecious (Inset 10.14), such as 

willow or cottonwood, an attempt to collect cuttings from both male and female plants in equal 

amounts should be made. If one of the objectives for using dioecious species is to promote 

or restore a species, donor plants must be located during periods of identifi able phenology, 

which is typically spring through summer. This might add an additional year to the timeline. 

To help preserve genetic integrity, it is recommended to collect from a minimum of 50 donor 

individuals within a watershed (See Chapter 6 for genetic transfer guidelines). Diff erentiating 

between individual plants within an area can be diffi cult with clonal species, such as willows 

and cottonwoods, because what often appear as a group of individual plants are actually 

off shoots from a single parent plant.

Diameter Size – The project objectives will determine which stem diameters must be collected 

(NRCS 1997). This must be assessed when a collection site is evaluated. 

Small diameter. Small diameter materials, called branched cuttings, average less than 1.0 inch 

in diameter and are derived from the fi ne branches of vigorously growing donor plants. This 

material is tied into long bundles to form live fascines (See Section 10.3.3.4, Live Fascines) or 

laid on the surface of the soil to form brush mattresses. Live fascines are placed in shallow 

trenches on slope contours to function like small water and sediment collection dams, or they 

are placed at an angle to the slope to facilitate slope drainage (See Section 10.3.3.3, Live Brush 

Layers). Small diameter materials are also used for branch packing and to vegetate geogrids 

and rock gabions. Additionally, small diameter materials are used for rooted cutting production 

at nurseries. The typical diameter size preferred by most nurseries ranges from 3/8 to 1/2 inch.

Medium diameter. Medium diameter cutting materials are used to make live stakes (See Section 

10.3.3.2, Live Stakes), which range in size from 1.0 to 3.0 inches in diameter. Stakes are tamped 

into the ground at right angles to the soil surface to secure small slumps, live fascines, and 

erosion control materials. Joint plantings are stakes that are driven between rocks or riprap, 

and must be greater than 1.5 inches in diameter and several feet long. Materials ranging from 

0.5 to 2.5 inches are used to revegetate live crib walls. Crib wall cuttings must be long enough 

to reach 4 to 6 feet back to the end of the wall. 

Large diameter. Larger diameter materials are used as dormant post plantings to stabilize 

streambanks. The diameter of these poles range from 3 to 5 inches and are 7 to 9 feet long. 

Large posts are not always easy to obtain in the wild, but can be produced from nursery 

stooling beds.

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Cutting Footage – The total length of cuttings available for harvest should be estimated for 

each potential cutting area. This can be roughly calculated by evaluating 10 to 20 donor plants 

and estimating the average length and number of usable stems (by diameter size categories) 

that could be obtained from each. The average length is then multiplied by the estimated 

number of plants in the cutting area to obtain a total estimated cutting footage. This will be the 

high end of an estimate, since most landowners are likely to place a restriction on the amount 

of cuttings that can be harvested at one time. For example, a landowner might limit the amount 

of cuttings that can be taken from an area to 25% in a riparian area. The cutting footage would 

be 25% of the total length of the cuttings. 

10.2.2.4 Determine Rooting Potential

Not all cuttings will root and become established plants when installed on a project site. The 

success rate of those that actually do become plants is dependent on 1) the percentage of 

cuttings that form roots when placed in an ideal growing environment, or the rooting potential 

and 2) the percentage of viable cuttings (those that root) that become established after a 

growing season, or the survival potential.

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Inset 10.14 – How to Tell the 

Diff erence Between Male and 

Female Willows and Cottonwoods

Identifying the sex of dioecious 

plants is easiest when they are 

fl owering or fruiting. Willow (Salix 

spp).catkins may appear before, 

during, or after new leaves appear 

in spring. Identifying anthers in 

male catkins (photo A) and pistils in 

female catkins (photo B) with a hand 

lens is relatively easy, especially 

with a little practice. Female plants 

can easily be identifi ed when the 

cottony seeds are mature (photo C). 

During the winter dormant season, 

it is possible to identify the sex of 

dormant cottonwoods by dissecting 

fl oral buds, although this is more 

diffi cult with willows. Detailed 

instructions on how to sex willows 

and cottonwoods can be found in 

Landis and others (2003). 

A

B

C

259
Rooting potential is analogous to germination rates obtained from seed testing. Seed tests 

are performed under uniform, ideal growing conditions, and are a measure of the potential 

of seeds to germinate (See Sections 10.2.1, 10.2.4, and 10.3.1). Rooting potential is similar to 

germination in that it assesses the potential of cutting materials to produce roots under an 

ideal rooting environment. The potential of cutting materials to initiate roots is the basis for 

determining how many cuttings to collect and the density to plant. For example, if the rooting 

potential of a specifi c collection is low, more cuttings will need to be planted at closer spacing 

to compensate for those cuttings that do not root.

Root potential tests have been developed for measuring the viability of nursery-produced 

plants (Ritchie 1985), but there are no standardized tests for determining the rooting potential 

of cuttings. Labs that off er seedling quality tests might, on request, use or adapt the root growth 

potential (RGP) tests developed for seedlings to assess the rooting potential of vegetative 

materials. Inset 10.15 gives one possible method for assessing rooting potential. 

Rooting potential is aff ected by several plant factors, the most important of which are 1) species, 

2) genotype, 3) date of collection, 4) portion of plant collected, 5) age of material, 6) condition 

of material, 7) preparation techniques.

Species – A small percentage of species in the western United States root consistently from 

cuttings. Those that root well can be cut and used directly on revegetation projects. Other 

species initiate roots only under controlled nursery environments, and must be grown into 

rooted cuttings before they can be planted on a project site. A list of commonly used native 

species that root from cuttings are shown in Table 10.13.

Genotypes – Within each species, there is variability in rooting potential. Some donor plants 

(genotypes) will have greater rooting potential than other plants. Unless tests are run, it is hard 

to know which donor plants are optimal rooters.

Date of Collection – The optimal time to collect cutting material is during plant dormancy. 

For most willow and cottonwood species, this period extends from mid-fall, after the donor 

plant drops its leaves, to bud swell in late winter to early spring. It is safe to assume that if donor 

plants have lost their leaves, cuttings will be at their highest rooting potential.

Planting unrooted cuttings within the dormancy period is not always possible because most 

construction work is curtailed during winter months. If unrooted cuttings must be planted 

outside the dormancy period, establishment rates will signifi cantly decrease. There are several 

alternative measures that can be taken: 1) collect cuttings during dormancy and keep in 

cold storage until they can be installed (See Section 10.2.2.7), 2) collect cuttings outside the 

dormancy period and plant more cuttings to compensate for the anticipated downfall (See 

Section 10.2.2.5), or 3) use rooted cuttings in lieu of unrooted cuttings (See Section 10.2.2.4).

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Table 10.13 – Some common species that can be propagated from vegetative material.

Willows (Salix spp.)

Cottonwoods (Populus spp.)

Snowberry (Symphoricarpos albus)

Pacific ninebark (Physocarpus capitatus)

Black twinberry (Lonicera involucrata)

Douglas spirea (Spiraea douglasii)

Salmonberry (Rubus spectabilis)

Quaking aspen (Populus tremuloides)

Redosier dogwood (Cornus sericea)

Chokecherry (Prunus virginiana)

Golden currant (Ribes aureum)

Woods’ rose (Rosa woodsii)

Manzanita (Arctostaphylos spp.)

Easy

Easy

Easy to Moderate1

Easy to Moderate1

Easy to Moderate1

Moderate1

Moderate1

Moderate

Moderate

Moderate

Moderate2

Moderate2

Moderate

Easy

Easy

Easy to Moderate1

Easy to Moderate1

Easy to Moderate1

Moderate1

Moderate1

Poor

Moderate2

Moderate2

Poor

Poor

Poor

Stems

 Species In Greenhouse

Rooting Potential

In Field Vegetative

Material

Stems

Stems

Stems

Stems

Stems

Stems

Roots

Stems

Roots

Stems

Stems

Stems

1 From Darris and Williams 2001

2 From Bentrup and Hoag 1998 260
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Inset 10.15 – Testing Method for Determining Rooting Potential for Willow and 

Cottonwood Species

Testing the viability of willow and cottonwood cuttings takes much of the guesswork out of 

establishing plants through this method of propagation. While is not a common practice in 

revegetation work, testing the viability of cuttings should be considered for similar reasons 

as seed testing. Most revegetation specialists would not think of applying seeds on a project 

without fi rst testing for germination, purity, and seeds per pound, yet not think twice about 

using cuttings without having tested them fi rst. This oversight can lead to higher costs, as 

well as low establishment rates.

There are no established testing procedures for assessing rooting potential of cutting 

materials. Until these tests are established, we present a means of root assessment that can 

be used to compare results from year to year. Ideally, a controlled environment, such as a 

greenhouse, is the best place to conduct a rooting potential test. Temperatures should range 

between 65 and 75 ° F degrees. Using bottom heat or rooting hormones is not necessary; 

in fact, for some species, it can be detrimental for rooting (Darris and Williams 2001). Where 

a greenhouse is not available, use an indoor space where relatively constant temperatures 

can be maintained. Grow lights should provide at least 12 hours of light per day. 

Fifteen samples, at a minimum, should be randomly collected from diff erent donor plants at 

each collection area. They should be of the same size and treated in a manner similar to what 

would be expected under normal operations. For example, if stakes with diameters between 

2 and 3 inches are to be collected in August and soaked for 10 days before planting, then the 

cuttings used for the tests would be of similar size, collected in August, and soaked in the 

same manner, and planted. Prepare each sample by cutting them into 12-inch lengths. Stick 

them 3 inches apart in pots that are at least 16 inches deep, fi lled with 1 part peat to 4 parts 

perlite. Cuttings should be stuck so that two buds are exposed above the media. 

After sticking, water the pots and set them in their testing location. At weekly intervals, 

observe the cuttings and note the status of the leaves developing from the buds. At 28 

days, record how many cuttings have developed new leaves, gently remove the media from 

around the cuttings, and lightly wash the stems. Viable cuttings should have developed 

roots during this period. Record how many cuttings did not initiate roots (see cutting on the 

left in picture below). For those cuttings that did establish roots, a quantitative estimate of 

root initiation can be measured by removing the roots from the stem and weighing the new 

roots or counting the number of new roots for each cutting. 

To interpret this data, you will have to assume that any cutting that did not initiate roots 

or develop foliage during 28 days, probably will not immediately initiate roots in the fi eld. 

A comparison of average root weights or number of roots between testing samples can 

indicate which collection sites or treatment methods will produce the best rooting materials. 

Those test samples with high average root weights should perform better than those with 

lower weights. 

261
Collecting plant materials outside 

the dormancy period has been tried 

in biotechnical engineering projects 

with varying degrees of success 

(Figure 10.55). Species that root 

easily, such as willows (Salix spp).

and cottonwoods (Populus spp.), will 

root from cuttings collected outside 

dormancy, albeit at very low rates 

(Steinfeld 2002; Steinfeld 2005). In 

some instances however, this may 

be the only option available to the 

revegetation specialist. When these 

are the circumstances, collecting 

outside the dormancy period should 

be done with an understanding 

of how establishment rates will be 

aff ected and whether the overall 

project objectives will be met. For 

large projects, it is important to 

conduct rooting and survival potential 

tests (Inset 10.15) several years before 

cuttings are installed so that the 

appropriate amount of cuttings can 

be collected and planting densities 

can be determined (See Section 

10.2.2.5). An alternative to dealing 

with low survival potential of wild 

cuttings is to establish stooling beds 

(See Section 10.2.5).

Portion of Plant – Most cuttings are taken from stems and branches. However, the rooting 

potential for some species is greatest when cuttings are taken from roots (Table 10.13).

Age of Material – The rooting potential changes with the age of the donor plant. Many species 

have greater rooting potential from new growth, while others perform better when materials 

are collected from older branches or stems. Species having a higher rooting potential in the 

older portions of the plant make excellent live stakes because the size of the material is often 

large enough to withstand being driven into the ground (Darris and Williams 2001). 

Condition of Material – Vegetative material from donor plants can be aff ected by insects and 

disease which can severely reduce rooting potential (See Section 10.2.5 for more discussion). 

Preparation Techniques – Several practices can potentially enhance rooting potential. One 

method involves soaking dormant cuttings in water prior to planting. Schaff and others (2002) 

found that soaking black willow (Salix nigra) for up to 10 days in water doubled the survival rates 

of large diameter, dormant cuttings over unsoaked cuttings. Some revegetation specialists 

have reported an increase in rooting potential of cuttings collected outside the dormancy 

period by stripping leaves from stems, while others have found this ineff ective (Steinfeld 2002). 

Soaking cuttings in hormones can increase rooting in some species (Shaw 2004), while it can 

be detrimental to others (Darris and Williams 2001). Testing rooting treatments on a small scale 

through rooting potential tests should be conducted prior to applying these methods on a 

larger scale.

10.2.2.5 Determine Survival Potential

Not all cuttings that initiate roots under ideal testing conditions will establish into plants when 

outplanted on a project site. The percentage of viable cuttings that root and survive one year 

after planting is called the survival potential. The survival potential is controlled by 1) climate, 2) 

soils, 3) planting methods, and 4) maintenance practices for each project. It can be determined 

though fi eld testing conducted prior to installing cuttings, or estimated from previous fi eld 

experience on similar sites using unrooted cuttings, rooted cuttings, or planted seedlings.

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Figure 10.55 – Collecting cuttings outside of plant 

dormancy as was done for the project shown in this 

photograph, can lead to extremely poor results. If 

this practice is considered, rooting potential tests 

should be performed fi rst.

262
Climate – Survival potential is strongly infl uenced by the water loss potential of the site (See 

Section 5.4). Sites with low moisture stress during root initiation (typically spring through early 

summer) will have high survival potentials. The longer cuttings can initiate and grow roots 

without being under moisture stress, the greater the potential for survival. Climates with high 

humidity during root initiation occur in riparian areas. 

Within a project area, survival potential often changes with aspect. Cuttings subjected to hot, 

dry conditions of south aspects typically will have a lower survival potential than north aspects. 

Survival potential also increases in areas that have occasional summer rainstorms that wet the 

soil profi le.

Soils – Survival potential is aff ected by soil water storage and accessibility (See Section 5.3). 

Soils with low water-holding capacity will have lower survival potentials than those with high 

water-holding capacity. Installation of cuttings on compacted soils will result in lower survival 

than loose or tilled soils. Areas that have high water tables during the growing season, such as 

slumps, seeps, and springs, will have higher survival potentials for riparian species.

Installation Methods – Compensations can be made for sites with poor soils or dry climates. 

One option is to install longer cuttings. Studies have shown that higher survival rates and 

greater vegetative growth can be achieved with longer cuttings (Rossi 1999). This is especially 

important on drier sites, since longer cuttings access deeper soil moisture. Cuttings up to 2 feet 

in length have been shown to produce better survival and growth on harsher sites (McElroy 

and Dawson 1986; Rossi 1999). In areas where freeze-thaw potential is high (See Section 5.6.2), 

shorter cuttings have a greater likelihood of being pushed out of the ground before they can 

form roots to anchor them in place. Survival rates are also aff ected by the quality of planting 

methods. For instance there can be a signifi cant decrease in survival when cuttings are planted 

without good soil–to-stem contact and many large air pockets. Section 10.3.3 covers the 

diff erent methods of installing cuttings.

Plant Maintenance – Survival potential can also be increased if the plants are maintained during 

the fi rst year after planting, including the control of competing vegetation and protection from 

animal browse (See Section 10.4, Post Installation Care of Plant Materials). 

10.2.2.6 Determine Cutting Needs

Once the survival and rooting potentials have been determined, the quantity of cuttings to 

collect can be calculated. The information needed for determining cutting quantities and 

cutting spacing (density) is:

 · Rooting potential,

 · Survival potential,

 · Target plant density,

 · Area to plant,

 · Desired established plant densities, and

 · Length of cuttings.

An example of how to calculate cutting quantities and planting spacing is shown in Figure 

10.56. In this example, the project objective is to stabilize the slope by installing willow stakes. 

In the short term, this practice will increase slope stability by physically “pinning” the surface 

soil. The primary benefi t to slope stability, however, will develop over time as the roots of the 

establishing willows begin to tie the soil particles together and increase soil strength. The 

desired spacing between established plants is 6 ft. When inventories are taken one year after 

planting, they should fi nd an established plant approximately every 6 feet (D), or approximately 

303 established plants for the entire planting site (E).

To achieve the desired density of established plants, we must determine how many cuttings 

to plant and the average spacing between installed cuttings. This determination is based 

primarily on the rooting and survival potentials (See Section 10.2.2.4 and Section 10.2.2.5). In 

this example, the rooting potential was 68% based on rooting potential tests. The survival factor 

was estimated to be around 35% from previous experiences on similar sites. These factors are 

used in the equation shown in Line F, to calculate the number of cuttings needed to install. To 

obtain 303 established plants, it would be necessary to install approximately 1,271 cuttings. 

This is approximately four times the number of established plants. It is necessary to install this 

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many to compensate for the number of cuttings that either do not root, or root and do not 

survive the summer. The planting spacing is calculated using the equation in Line I. Cuttings 

must be installed at half the distance of the desired established plant spacing. Since the site 

conditions in this example are harsh, the cuttings will need to be planted deeply to access soil 

moisture. For this reason, the cutting lengths are approximately 2.5 ft. Multiplying 2.5 ft by the 

number of cuttings needed (F) gives the total length of cuttings that must be collected (H). 

Knowing that 3,178 ft of cuttings are needed, the number and location of cutting areas can be 

selected from a cutting area map, and a contract can be developed. 

10.2.2.7 Long-Term Storage

If cuttings are not installed immediately, long-term storage will be required. Cuttings collected 

in the fall or winter and stored until the following spring or summer must be held in refrigerated 

units. The optimum temperatures for long-term storage range between 28 to 31 °F. Freezing 

temperatures prevent disease and curtail respiration, thereby increasing cutting viability. 

If freezing is not possible, then storing cuttings at temperatures between 33 and 35 °F should 

maintain cutting viability for several months. 

For long-term storage, cuttings should be relatively free of leaves and other material that might 

mold in storage. They must be packaged in plastic or storage bags so they will not dry out. 

Cuttings should not be wrapped in moist burlap or placed in plastic bags, especially if cuttings 

are not frozen. Diseases could potentially develop that will rot the stems.

10.2.2.8 Develop and Administer Contracts

A good plan that includes the location of cutting sites and how the cuttings will be treated, 

transported, and stored will be the basis for the development of a collection contract. The 

contract must specify:

Cutting Locations – A map or GPS locations must identify cutting areas and specify an 

estimated range of cutting quantities (See Section 10.2.2.3). If the contractor elects to collect 

from other areas, then these areas must be approved prior to cutting. For each cutting area, the 

percentage of the donor population that can be collected should be specifi ed. Typically this is 

no greater than 25% of the population.

Dates of Collection – The contract must specify a period of time that cuttings must be collected 

(See Section 10.2.2.4). Collecting outside this time period must be discussed in advance with 

the revegetation specialist.

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Figure 10.56 – This spreadsheet can be used to calculate the number of cuttings to collect and 

how close to plant them on the project site.

A Area to plant: 0.25 acres Area that will be planted with cuttings

I 2.9 feet Distance that cuttings must be planted 

from each other

SQRT ((43,560 * A) / F) =

H F * G = 3,178 Total footage of cuttings to collect for site

G 2.5 feet

feet

Cutting Length: Approximate length of cuttings

F 1,271 cuttings Number of cuttings that need to 

be planted

E * (100/B) * (100/C) = 

E 303 plants Desired number of established plants 

after one growing season

(43,560 / (D * D)) * A = 

D 6.0 feet Desired distance between established 

plants after one year

Target plant spacing (1st year): 

C 35 % Percent of cuttings that root which are 

established one year after planting

Survival potential:

B 68 % Percent of cuttings that root under 

ideal rooting environment

Rooting potential:

264
Collection Size, Lengths, and Quantities – Quantities must be specifi ed for each size category. 

For example, if material is to be used for stakes, then a specifi cation might require 200 stakes, 

18 inches long, with a range of diameters between 1.0 inch to 3.0 inches.

Collection Methods – The contract should identify how the contractor will collect the cuttings. 

For example, it should state how the contractor will identify which end of a stake is basal and 

which is terminal. This is typically done by cutting the basal end of each stake at an angle. The 

contract should also specify how the cuttings will be packaged or bundled. Contracts often call 

for all stakes to be aligned with basal ends of the cuttings in the same direction. Bundle sizes 

or weights must be specifi ed. The bundles must be light enough to transport by one person 

(45 lb or less). The contract must also state that the bundles must be securely tied or bundled 

together for hand transportation.

Source Identifi cation – Each bundle must be identifi ed with a Forest Reproductive Materials 

Identifi cation Tag (Figure 10.57), which specifi es the species, collection location, elevation, and 

date of collection.

Special Treatments – Special measures such as soaking must be stated in the contract. If 

soaking is required, then the location of the soaking area must be identifi ed on a map (See 

Section 10.2.2.4). 

Temporary Storage and Transportation – The contractor must address how cuttings will be 

temporarily stored when the weather is warm or dry. Cuttings must not be allowed to dry out 

once they are collected. Temporarily storing in shaded areas covered by plastic sheets or wet 

burlap are acceptable methods. Delivery of cuttings must be done in a manner that does not 

allow the cuttings to dry. Closed transportation or covering with plastic for long distances 

should be considered.

10.2.3 COLLECTING WILD PLANTS

10.2.3.1 Introduction

Wild seedlings, commonly referred to as wildlings, are indigenous plants growing in their 

native habitat (Therrell and others 2006). They are naturally reproduced outside of a nursery 

situation, but can be transplanted directly into a restoration site or into a nursery for culturing 

and future use.

The collection and use of wildlings in native plant restoration can be a viable alternative to 

direct seeding, nursery seedlings, or rooted cuttings. As with wild cutting collections (See 

Section 10.2.2), wildlings can be used in situations where it is diffi cult or impossible to collect 

or use seeds for plant production because : 1) the plant either does not produce seeds or 

produces seeds very infrequently; 2) seeds are often unfi lled or non-viable; 3) seeds have a very 

narrow collection window; 4) seeds have already dispersed prior to collection planning; and 5) 

insects or animals are a problem with collection (Priadjati and others 2001; St John and others 

2003). Unlike cuttings, they can be available immediately with little to no transport costs, and 

no direct nursery costs, if used within the same time frame of collection.

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Figure 10.57 – A forest reproductive material identifi cation tag should be fi lled out and 

attached to each bundle of cutting material.

FOREST REPRODUCTIVE MATERIAL

IDENTIFICATION TAG

U.S.D.A. FOREST SERVICE

1) Identification Code:

(Feet above sea level)

(Person filling out tag)

2) Number of Trees 3) Ranger District 4) Elevation

4) Tree Numbers:

Species Forest BZ/Seed Zone Type Coll. Elev. Band Year Cert.

(TI Collections: affix bar code tag if available)

7) Accession No. 8) Plant Association

9) Alpha Code

10) Collection Date 11) Signature

6) Area of Collection

T.

/

/ /

R. S.

265
There are several advantages to using wildlings in restoration plantings. Large wildlings provide 

“vertical relief” (visual prominence) more quickly to a site than other methods, and, depending 

on the species and environment, will establish and spread quickly (Hoag 2003). Use of wildlings 

reduces the risk of introducing non-native organisms such as weeds and pathogens (Therrell 

and others 2006). If reproduction of the plant is more successful via rhizomes (e.g., sedges), 

transplanting wildlings may be the most effi cient and eff ective method for reestablishing these 

species (Steed and DeWald 2003). In addition, if plant propagation is diffi cult from seeds or 

rooted cuttings, use of whole plants may be the only alternative for a particular species.

Transplanting of wildling plants, however, can be unsuccessful for a number of reasons. 

Wildlings are often growing in stressful conditions, and do not recover from transplanting 

shock as quickly as cultivated seedlings. Wildlings often have smaller, coarser root systems than 

cultivated seedlings, or heavier taproots which are not easily removed from soil in their entirety 

(St John and others 2003). Successful transplanting requires experience, skill, proper handling, 

ideal temporary storage, and proper care of the plant both before and after transplanting.

10.2.3.2 Develop Timeline

Although wildling plants may provide an opportunity for quick establishment of larger plants 

on restoration sites, several factors must be considered in the planning process which could 

impact their availability. Suitable locations that can provide the number of plants required 

must be determined. If large quantities of plants are necessary, several years may be required 

to identify these locations. Once sites are identifi ed, 1 or 2 seasons of plant preparation prior to 

removal, transport, and transplanting may be required (See Section 10.2.3.5).

Wildling plants may be removed from their native site and either transplanted immediately or 

transported to a nursery, potted, and cultured for future outplanting. Transplanting following 

removal may occur if the plant source is undisturbed areas outside the restoration site. If plants 

are removed prior to site disturbance, or if additional time is needed for production of sturdy 

plants, culturing in a nursery for some specifi ed period of time may be necessary. Lead time 

of 1 to 2 years may be necessary for nursery-assisted wildlings, depending on the situation. 

This lead time may include contract procurement and administration for both collection and 

nursery culturing.

10.2.3.3 Locate Wildling Collection Areas

Potential sources for wildling plants can be identifi ed through fi eld surveys during the 

vegetative assessment phase (See Chapter 6). Sites should be located on maps and both plants 

and sites should be assessed for the following traits:

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Figure 10.58 – Wetland plants are often salvaged from areas that are planned for disturbance. 

Removing plants from wetland settings can be diffi cult due to wet soils and massive root 

systems of many species. The heavy weight of these plants makes transportation and handling 

diffi cult. Tubs (A) are used for hand-transporting to planting sites while pallets (B) have been 

used for large quantities.

A B

266
Accessibility – Handling of wildling plants during removal and transport is a critical factor in 

ensuring survival. Roots may require protection if the rootball is not totally contained in soil; 

or plants may be heavy if the rootball is intact. Therefore, it is necessary that collection sites be 

accessible by roads. Since most collections will be taken in fall or early spring, it is also necessary 

to determine whether or not road conditions at these times of year will preclude collection.

The best collection areas may not always be found within the project site, so large areas 

surrounding the project may need to be surveyed for plants. Costs will increase substantially if 

it is necessary to transport plants for long distances.

Land Ownership – Permission to remove plants must always be obtained from either the private 

landowner or public land management agency. In addition, any required permits should be 

obtained from state or federal agencies to ensure compliance with regulations (Hoag 2003).

Viability – If possible, areas of healthy forest or rangeland areas should be designated as 

collection sites (Priadjati and others 2001). Sites should contain healthy, vigorous, and adequately 

sized material with a minimum number of unhealthy plants (St John and others 2003). Stunted 

needles, off -color foliage, and poor annual growth are indications of stress plants that should 

not be collected. Plants should only be removed from sites that show good regeneration over 

the area (Hoag 2003). Determining the viability of the collection material and timing of use (See 

Section 10.2.3.4) should be completed prior to selection of the collection site. It is important 

to transplant wildlings into similar growing environments. For instance plants growing under 

shade should be placed back into a shaded environment to achieve optimum viability.

Genetics – One of the disadvantages or limitations of using wildlings, or any form of asexual 

propagation, in restoration is the potential to restrict the genetic diversity of the plant 

population. As adequate population sampling is important to maintain this diversity, it may 

be advisable to identify several sites over a large area from which to collect (St John 2003). 

Collecting many plants over a large area will help capture both inherited and environmental 

variation. However, sites must be chosen carefully so that they are reasonably similar. 

Prior to collection, it is necessary to determine whether species are monoecious (male and 

female reproductive structures on the same plant) or dioecious (male and female reproductive 

structures on diff erent plants). If the species of interest is dioecious, both male and female 

plants will need to be collected in somewhat equal proportions. If one of the objectives for 

using dioecious species is to promote, restore, or increase species, then target plants must 

be located during a period when reproductive phenology is evident, which is typically spring 

through summer.

10.2.3.4 Determine Transplanting Versus Nursery Culture

Although cost may be the biggest deciding factor in whether wildlings are collected for 

immediate transplant or growing in a nursery, other factors should enter into the decision in 

the restoration plan.

Timing – Wildling plants should be transplanted into their new location as quickly as possible. 

If plants are to be collected from sites outside the disturbed area, these can potentially be 

removed and transplanted to the restoration site within the same time frame. However, if plant 

removal is part of a salvage operation, where plants are located within the area of disturbance, 

then plants could be transported to a nursery or similar growing situation. Plants should be 

transplanted into pots and maintained until the appropriate outplanting season.

Species – Some plant species may be more successful than others for direct transplanting 

from one site to another. Plants that spread underground or with stolons will perform well, 

although dry, compacted sites will slow the rate of spread signifi cantly (Therrell 2006). Species 

that recover quickly from root damage, such as willows (Salix spp).and cottonwoods (Populus

spp.), will also perform well when large plants are needed quickly. These types of plants may 

lend themselves easily to transplanting within the same time frame as removal. 

Plants with taproots, such as conifers and many shrubs, and plants with long, brittle horizontal 

roots, such as heather or vine maple, are diffi cult to transplant. Special care must be taken 

during removal to extract as much of the roots as possible. To ensure a higher success rate, 

further culturing in an optimal environment following removal may provide a healthier, more 

viable plant for outplanting.

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Size and Availability – If wildling plants of the target species are plentiful and appropriately 

sized on undisturbed sites, immediate transplant during the appropriate season is feasible. 

However, if available wildlings are smaller than desired, an additional 1 or 2 years of nursery 

culture may provide a better plant for colonization of the site. 

Certain plants have the ability to root by layering, such as pinemat manzanita (Arctostaphylos 

nevadensis). If entire plants are not plentiful, portions of individual plants can be removed and 

cultured in a nursery situation for outplanting the following year.

10.2.3.5 Collection and Handling

Date of Collection and Timing of Transplanting – The season during which collection and 

transplanting occur has been shown to dramatically aff ect the survival and growth of wildling 

plants (Yetka and Galatowitsch 1999). Plants allocate carbohydrates and nutrients during various 

phases of phenological development. Diff erent levels of tolerance to transplanting stress 

during the year are the result of physiological needs shifting among shoot and root growth, 

fl owering and seed production, and storage. In addition, seasonal variation in environmental 

factors, such as soil moisture and temperature, can aff ect planting establishment (Steed and 

DeWald 2003).

Timing of collection will depend on whether the wildlings are to be transplanted in the same 

time frame or cultured in a nursery. If wildlings are to be transplanted into the restoration site 

following collection, the chances for survival will increase for most species if operations occur 

in winter to early spring. The seedlings are dormant during this period and can handle the 

stresses associated with transplanting. There is also less chance of damaging new roots that 

occur during the spring and fall. In addition, planting early extends the period for root growth 

prior to soil-drying in summer. 

Collection could occur in either fall or spring if wildlings are to be cultured in a nursery. However, 

if plants are collected in the fall, care must be taken to avoid excessive root damage, since plants 

will not be dormant. Due to the perishable nature of wildlings, the timing of collection must 

be coordinated with the nursery to assure that the facilities, supplies, equipment, and labor 

are available following harvest (St John 2003). Once collected, plants should be transplanted 

immediately into containers.

Genetics – Collection of wildlings can consist of a single plant, a clump, or several pieces of a 

plant that have rooted through layering (NRCS 1997). A collection of individual plants should be 

large enough to assure adequate population sampling. A minimum of 50 plants within at least 

a range of 1 mile from the restoration site is recommended when possible.

Source Identifi cation – Every collection must be identifi ed with a Forest Reproductive 

Materials Identifi cation Tag, which specifi es the species, collection location, elevation, and date 

of collection (See Figure 10.53 in Section 10.2.1, or Figure 10.57 in Section 10.2.2).

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Figure 10.59 – Be sure to select small plants with a protective ball of soil around the roots (A). 

Do not attempt to transplant plants if the soil falls off the root system (B).

A B

268
Quality and Size – Only healthy, turgid, moderately vigorous, and adequately sized wildlings 

should be collected for either transplanting or nursery culturing. Unhealthy or stressed plants 

should be avoided. 

Although species dependent, successful transplanting typically increases as plant size 

decreases (St John 2003). Transplanting of large shrubs and trees is usually unsuccessful. 

Their root-to-shoot ratio is unbalanced, and these plants often do not recover from or survive 

transplanting shock. Transplanting of larger willows, sedges, or herbaceous material into 

riparian zones, however, may be appropriate depending on the vegetative competition and 

other establishment conditions (Hoag 2003; Steed and DeWald 2003). 

Handling, Transport, and Storage – Collection of wildling plants will be most successful if the 

soil is moist during plant removal. If precipitation has not occurred, irrigation prior to lifting 

would be desirable. Removal and transplanting should only occur in the mornings on cool, 

cloudy days, when the plant is fully turgid.

A tile spade or similar fl at-bladed shovel is the best tool for small to medium plant removal. 

Using the “dripline” of the plant as a guide, make shovel cuts with the blade as perpendicular to 

the surface of the ground as possible, since maintaining an intact ball of soil around the roots 

is important (Figure 10.59). Root morphology should also be considered in this process. Roots 

growing in deep soils or arid soils will tend to grow down rather than out. Roots growing in 

shallow soils will tend to spread, requiring a much larger area of disturbance (Therrell 2006). 

The shovel, as well as hands, can be used to lift the root ball gently out of the hole while attempting 

to keep the root ball intact. Hand pruners can be used to cut away woody roots that do not come 

free with the shovel. The root ball can then be transferred to a suitable container (large bucket, 

pot, burlap, or plastic bag) for transport to the transplanting site (Therrell 2006). If wildlings are 

to be transported to a nursery, plants should be placed in plastic bags in coolers. Plastic bags 

should also contain moistened towels 

or similar material if roots are not 

covered with soil.

A tree spade can be used if larger 

plants are to be excavated and 

transplanted (Figure 10.60). The 

factors important for using a tree 

spade are: 1) the terrain is accessible 

to the tree spade equipment (slope 

gradients no greater than 20%), 2) soils 

are relatively free of cobble size rock 

fragment, and 3) soils are moist. In this 

operation, planting holes are created 

fi rst, then plants are excavated, 

moved, and replanted. The size of the 

plant to be transplanted depends on 

the soil volume that can be removed 

by the tree spade. Typically plants up 

to 6 feet tall can be transplanted with 

success. Taller trees should be irrigated 

into the soil to improve survival. Using 

a backhoe has also been successful in 

transplanting large willow clumps 

(Hoag 2003).

Wildlings should be transplanted 

into their new location as quickly as 

possible, with minimal to no storage 

time. All vegetative material must 

be kept cool and moist during the 

process. If wildlings are transported 

to a nursery, the plants should be kept 

in a cooler and transplanted into pots 

within 1 to 2 days of collection. 

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Figure 10.60 – Plants can be excavated from the 

soil using the drip line (dashed lines) as a guide.

269
10.2.3.6 Survival Potential

As with rooted cuttings (See Section 10.2.2.5), not all wildlings will become established and 

thrive following transplanting. Survival is controlled by climate, soils, planting methods, and 

maintenance practices on the project.

Climate – Water loss potential (See Section 5.4) is probably the main determining factor for 

survival on many sites in the western United States. Sites with low moisture stress during 

root initiation (spring through early summer), and sites that have the potential for longer root 

initiation periods, will have higher survival. 

Within a project area, aspect can also aff ect root initiation and survival. Transplanted wildlings 

subjected to hot, dry conditions on southern aspects have a lower potential for survival than 

those on cooler northern aspects.

Soils – Survival of wildlings is aff ected by soil water storage and accessibility (See Section 5.3). 

Soils with low water-holding capacity or compacted soils will have lower survival than those 

with high water-holding capacity and greater porosity. 

Planting Methods – Good transplanting techniques will improve the survival rates of wildlings 

signifi cantly. Planting methods are the same for wildlings and nursery-grown seedlings. 

Common mistakes include planting too shallow or too deep, planting too loosely, damaging 

roots by exposing them to air, or failing to place root systems properly (Therrell 2006).

Ideally, transplanting should occur on a cool, cloudy day. Planting holes should not be allowed 

to stand empty for an extended period of time, as soil will dry rapidly. When possible, microsites 

should be used (rocks, logs, depressions, and so on) to provide protection from the sun or wind.

Plant Maintenance – Survival potential can also be increased if the plants are maintained 

during the fi rst year after planting. Practices including the control of competing vegetation and 

protection from animal browse. For large wildlings, irrigation during the summer will improve 

survival. Also large wildlings might need additional support depending on such site conditions 

as wind and snow.

10.2.3.7 Develop and Administer Contracts

A plan that includes the location of collection sites, and how the wildlings will be handled, 

transported, transplanted, and stored (for short periods of time) will be the basis for the 

development of a collection contract. The contract must specify:

 · Collection Locations. A map or GPS locations must identify wildling collection areas and 

specify a range of quantities that can be expected. If the contractor elects to collect from 

other areas, then these areas must be approved prior to collection. For each collection 

area, it should be specifi ed what percentage of the natural population can be collected.

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Figure 10.61 – Mechanical tree spades (A) can extract large plants quickly. A planting hole must 

be excavated prior to transplanting (B) and this can be accomplished with a tree spade. Photo 

credit: Chris Jensen, USFS.

A B

270
 · Dates of Collection. The contract must specify a period of time that the collections can 

be made (See Section 10.2.3.5). Collecting outside of this time period must be discussed 

in advance with the revegetation specialist.

 · Collection Quality and Size. Minimum and maximum plant sizes should be specifi ed in 

the contract. In addition, specifi cations for health and vigor should be included.

 · Collection, Handling, and Storage Methods. The contract should identify how the 

collections will be made, how the wildlings will be handled and processed following 

removal, and how wildlings will be temporarily stored prior to transplant or transport 

to the nursery. 

The contractor must address how plants will be temporarily stored when the weather is warm 

or dry. Wildlings must not be allow to dry out once they are collected. See Section 10.2.3.5 for 

proper handling and storage methods. 

10.2.4 NURSERY SEED PRODUCTION

10.2.4.1 Introduction

Most revegetation projects require large quantities of source-identifi ed seed. The most 

common approach to obtaining such quantities is to issue seed increase contracts. In these 

contracts stands of grasses and forbs are established from source-identifi ed seed (typically wild 

seed collections) and cultured specifi cally to produce seed (Figure 10.63). Usually the seeds are 

produced by the end of the fi rst or second year of production. 

Considering the costs and amounts of seeds that can be obtained from wild seed collection, 

propagating grass and forb seed is very effi cient. For example, mountain brome (Bromus 

carinatus) requires 8 pounds of wild seed to sow an acre of seed fi elds. At the end of the fi rst 

year, the seed collected from the fi eld will average 800 pounds, a hundred-fold increase. 

For most species grown in production beds for two years, the return is at least 50 pounds of 

seed produced for every pound of wild seed collected and sown. In some cases 100 pounds 

are collected per pound of wild seed sown. This section will outline the steps required for 

developing and administering seed increase contracts. 

10.2.4.2 Develop Timeline

Seed production varies by species but typically it takes three years to obtain seed. This involves 

one year to obtain seed from wild collections, and at least two years for seed production (Figure 

10.64). There are a series of steps or tasks that are required to obtain seed that will be discussed 

in detail in this section:

 · Determine seed needs,

 · Obtain starter seed,

 · Develop and award contract,

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Figure 10.62 – Transplant wildlings 

immediately following collection to minimize 

moisture stress.

271
 · Administer contract, and

 · Store seed.

Early in the planning phase a rough approximation of the quantity of needed seed for each 

species must be determined. Seed quantities will be refi ned as planning progresses, but 

because of the amount of time that is takes for wild seed collection and seed production, it 

is important to make an estimate early in the planning stages. Developing and awarding wild 

seed collection contracts is the fi rst task and this can take several months (See Section 10.2.4). 

To avoid missing the seed collection window, these contracts must be awarded by early spring, 

otherwise an additional year will be needed for wild seed collection.

Seed production contracts should be awarded by mid-July for fall sowing and late January for 

spring sowing. It is important to prepare and award seed increase contracts well in advance of 

sowing to allow the contractor enough time to prepare and sow their fi elds. Specifi c sowing 

dates will diff er for each seed producer because of diff erences in geographic location, climate, 

or experience. Some growers may want to certify the seed, so this may require additional 

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Figure 10.64 – Up to three years should be allowed when obtaining nursery grown seed because 

of the time it takes to obtain wild collected seed and obtaining seed from seed producers.

Determine seed needs

Seed Production

Tasks

Year

Obtain“starter”seed

Develop & award contract

Work with growers

Store seed

Develop sowing plan

-3 -2 -1 0 1

Road Construction Sow

Figure 10.63 – A variety of species 

can be propagated for seed. In this 

photograph small seedlots of forbs are 

being propagated. The beds in the upper 

left are western buttercup (Ranunculus 

occidentalis); lower left is fragrant 

popcornfl ower (Plagiobothrys fi guratus), 

and the bed on the right is elegant 

calicofl ower (Downingia elegans).

272
preparation time as well. It is benefi cial to contact the potential growers prior to award of 

contracts to fi nd out when sowing and fi rst harvests are expected. Once wild seed has been 

collected, cleaned, and tested, it is delivered to the seed producers. 

Seed increase contracts should cover a span of at least two years, to account for the possibility 

of a low fi rst year harvest. Seed harvests take place during the summer and seed cleaning in the 

fall of each year. Once seed has been cleaned, the grower submits a sample from each seedlot 

to a seed laboratory for testing. Seed testing typically takes place in the fall and is completed 

in several months. Seed is placed into seed storage until it is needed. For many revegetation 

projects, the seed that is harvested in the summer is needed for immediate fall sowing. This can 

be accomplished if those seedlots are put on a “fast track” for seed cleaning and testing. The seed 

production contract should state those seedlots that need to be ready for early fall sowing.

10.2.4.3 Determine Seed Needs

Determining total seed quantities for a revegetation project must be done as soon in the planning 

process as is feasible since wild seed collection contracts and seed propagation contracts are 

based on these fi gures. At this point, only a rough approximation of seed needs is required. 

Calculating the needed quantities of seed is performed for every species that will be used on a 

revegetation project. Each species requires a set of data which must be estimated since specifi c 

seed data is unavailable at this point in planning. The information that is needed includes an 

estimate of the following factors: 

 · Pure live seeds per pound,

 · Field survival,

 · Target seedling density,

 · Target species composition, and

 · Area to seed.

Pure Live Seeds Per Pound (PLS/lb) – The quality of seedlots can vary greatly. One method to 

assess seed quality is to calculate % pure live seed (PLS). This value represents the percent of 

the gross seed weight composed of viable seeds. For example, if a seed producer did not clean 

the harvested seed of a seedlot very thoroughly, the PLS would be low because there would be 

a lot of additional weight associated with non-seed debris. Seedlots that were cleaned well, on 

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Figure 10.65 – Pure live seed (PLS) is the percent of the bulk seed weight that is composed of 

viable seed. In this example 95% of the bulk weight is composed of seed and of this seed 83% 

was found to germinate from seed tests. Multiplying % purity by % germination gives % pure 

live seed. 

95% Purity 83% Germination

12 seeds 5% debris 2 dead 79% PLS

Purity

Test

Bulk

Seed

Germination

Test

Pure Live

Seed

273
the other hand, would have a higher PLS because the debris weight would have been removed. 

Seedlots that have higher germination rates also have higher PLS. These two factors, % purity 

and % germination, when multiplied together and divided by 100, give the pure live seed (PLS) 

of a seedlot. The concept of PLS is illustrated in Figure 10.65. In this example, purity of a grass 

seedlot is 95% and germination is 83% which results in a PLS of 79%. 

Another example of calculating PLS/lb is shown in Figure 10.66 for western pearly everlasting 

(Anaphalis margaritacea). For this seedlot the estimated purity is 60% which indicates that over 

half of the gross weight of seed is actually viable seed and the remaining part is either debris or 

non-viable seed. Multiplying this value by the percent of seeds per pound and by the percent 

of germination will yield the number of viable seeds per pound. In this example, the number 

of seeds in a pound of a western pearly everlasting seedlot is tested at 8,000,000. Multiplied by 

60% purity and 85% germination gives a value of approximately 4,080,000 PLS per pound of 

bulk seed. This value can be used in sowing calculations as shown in the example. Keep in mind 

that for each additional seedlot in a mix, similar calculations will have to be made. Estimates for 

purity, germination, and seeds per pound can be obtained from Table 10.14, seed inventories, 

or seed extractory managers. 

Field Survival – Field survival factors account for the viable seeds that, for one reason or another, 

do not grow into plants within the year after seeding. It accounts for viable seeds that did not 

germinate because of the harsh site conditions, or did germinate but could not survive the site. 

The fi eld survival factor refl ects the harshness of the site. For example, seeds that are sown 

under mulch on a moist, cool site will survive better than seeds sown on hot, dry sites without 

mulch, in which case the survival factor would be much lower. Only an estimate of fi eld survival 

can be made at this time, based on general understanding of the site (See Section 10.3.1.5 

for more discussion on estimating survival). Choosing a survival factor between 3% (poor site 

conditions and poor seeding practices) and 25% (good site conditions and practices) should 

be suffi cient for this estimate. In Figure 10.66, the fi eld survival was set very low because of the 

harshness of the site.

Target Seedling Density – The target fi rst year density indicates the number of plants/square 

foot that is desired one year after sowing. This is the target number of seedlings, for all species 

sown, in a one square foot area. Seedling densities range from a target of less than one plant 

per square foot for shrub and tree species to 10 and 25 seedlings per square foot for grasses 

and forbs (See Section 10.3.1.5).

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Figure 10.66 – Determining the quantity of seed that will be needed for a revegetation project 

can be made by completing this spreadsheet for each species. The estimated pounds of seed 

determined for each species can be the basis for ordering seed through a seed increase contract. 

This example calculates the quantity of western pearly everlasting (Anaphalis margaritacea 

[ANMA]) seeds needed for a project.

A Number of seeds/lb: 8,000,000 seeds/lb From Table 10.14 or other sources

I 0.9 lbs/acre Pounds of ANMA to sow on a per acre basis

H 83 PLS of ANMA to sow per ft2

43,560 * H / D 

J Area to seed: 25 acres Total area for seed mix

K I * J = 22 lbs Total ANMA needed 

G 10 %

PLS/ft2

Percent of total plants composed of ANMA

(F / E) * G =

F 25 seedlings/ft2

Desired number of seedlings per square

foot — all species (10 to 30 for grasses

and forbs)

Target composition

E 3 %

Estimate of the pure live seeds that become 

seedlings (as low as 3% for harsh sites and 

up to 25% for excellent sites)

Target seedling density: 

Field survival: 

D A * B / 100 * C /100 = 4,080,000 PLS/lb Pure Live Seeds (PLS) per bulk pound of seed

C Germination: 85 % From Table 10.14 or other sources

B Purity: 60 % From Table 10.14 or other sources

274
Target Species Composition – The target composition defi nes the percent of established 

plants that are made up of each sown species. For example, if three species are sown, the target 

composition of plants might be 50% species A, 35% species B and 15% species C. The target 

species composition is developed from reviewing fi eld surveys of disturbed and undisturbed 

reference sites. In the example shown in Figure 10.66, only 10 percent of the composition of 

plants is targeted to be pearly everlasting.

Area to Seed – This is the total area that is planned to be revegetated from seed based on the 

estimated acres presented in the preliminary road plans.

In the example shown in Figure 10.66, the seed needs for pearly everlasting is calculated to be 

approximately 22 pounds for the entire 25 acre project. This might seem like a very low amount 

of seed for a project of this size, but it refl ects the high live seeds per pound for this species.

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Table 10.14 – A seed increase reference table showing the approximate maximum cleaned seed 

needed for a seed producer to produce a 1-acre production fi eld. It also shows average fi rst and 

second year yields and germination and purity standards for commonly produced species.

Sowing Rates

(lbs of clean 

seed to sow 

per acre)

8

6

6

8

8

4

6

8

10

6

2

2

3

3

5

2

5

2

1

200

450

0

25

25

50

0

150

800

0

0

150

300

600

0

110

100

165

50

300

200

125

250

160

400

200

750

600

150

130

500

600

350

150

510

190

165

50

140,000

110,000

110,000

125,000

130,000

450,000

120,000

150,000

70,000

100,000

2,500,000

2,315,000

1,314,000

2,000,000

225,000

2,500,000

275,000

3,000,000

8,000,000

75/95

65/96

75/90

75/90

75/95

75/90

80/85

50/95

85/90

50/95

75/75

80/97

75/97

80/95

50/95

75/90

50/95

85/98

60/85 

Species

Bluebunch Wheatgrass

(Pseudoroegneria spicata)

Blue Wildrye

(Elymus glaucus)

Bottlebrush Squirreltail

(Elymus elymoides) 

California Oatgrass

(Danthonia californica)

Basin Wildrye

(Leymus cinereus)

Idaho Fescue

(Festuca idahoensis)

Indian Ricegrass

(Oryzopsis hymenoides)

Lemmon’s Needlegrass

(Achnatherum lemmonii)

Mountain Brome

(Bromus carinatus)

Needle and Thread 

(Hesperostipa comata)

Pinegrass

(Calamagrostis rubescens)

Prairie Junegrass

(Koeleria macrantha)

Sandberg Bluegrass

(Poa secunda)

Slender Hairgrass

(Deschampsia elongata)

Thurber’s Needlegrass

(Achnatherum thurberianum )

Tufted Hairgrass

(Deschampsia caespitosa)

Western Needlegrass

(Achnatherum occidentale)

Common Yarrow

(Achillea millefolium)

Western Pearly Everlasting

(Anaphalis margaritacea)

Average first 

year yields

(lbs/ac)

Average 

second year 

yields

(lbs/ac)

Average 

seeds per

pound

Average 

germination/

purity of 

harvested 

seeds

275
10.2.4.4 Obtain Starter Seed

Once the seed needs for a project are determined then the next step is to obtain starter seed to 

supply to the seed producer. Seed furnished to the seed producer must be of high quality and 

tested for purity, germination (or TZ), seeds per pound, and noxious weed content (See Section 

10.2.1.7 for seed testing). Seedlots with high weed content will produce weedy fi elds. It is very 

expensive to weed non-target species out of seed production fi elds or clean non-target seeds 

from harvested seedlots, so it is important to give seed producers only the highest quality 

seed. It is worth the investment of sending all wild seed collections to a seed extractory to be 

cleaned prior to sending to the seed producer. Section 10.2.1.3 discusses how to determine 

how much wild seed to collect for starting seed production crops.

There will be some projects where not enough wild seed is collected to establish a seed crop 

through seed sowing. In these cases, small collections of seed can still be used by fi rst sowing 

seed in small plugs (1 to 2 cubic inch size) at a nursery, then transplanting the plugs into a seed 

production fi eld at low densities (<1 seedling per foot). Not only will this reduce the amount 

of seed needed to establish a seedbed but seed production from these beds is often greater 

because plants are evenly spaced.

10.2.4.5 Develop Contract

The seed production contract must state for each seedlot being grown:

 · Seedlot ID,

 · Years each seedlot will be in production, 

 · Minimum annual seed yields for each seedlot, and

 · Minimum purity and germination rates.

Minimum annual seed yields and average germination and purity rates can be obtained from 

Table 10.14. The years that a seedlot 

will be in production will vary by 

species and lead-time (See Section 

10.2.1.2 for further discussion).

In addition, the seed production 

contract must address what is 

required or expected of the contractor 

in respect to the following criteria:

 · Seed production experience;

 · Timelines;

 · History of production fi elds;

 · Location of other seed crops;

 · Irrigation system;

 · Culturing practices;

 · Control measures for nontarget species;

 · Seed harvest methods;

 · Seed cleaning, packaging, 

and labeling; and 

 · Seed testing. 

The response to these criteria 

becomes the basis for selection of 

contractors. 

Seed Production Experience – Seed 

production is a specialized form 

of agriculture requiring diff erent 

growing strategies and equipment. 

While many seed producers have 

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Inset 10.16 – Source Identifi ed Straw Bales

A secondary product from the seed production 

contracts is the straw that remains after harvest. 

This material can be used for erosion control or 

seed covering. It can be used as a mulch and has 

the additional advantage of being a source of 

unharvested viable seed. This product must be 

treated similarly to certifi ed straw sources (See 

Section 10.1.3). There should be no noxious or 

undesirable weed seed in the bales. A visit to the 

seed production fi elds prior to seed harvest will 

indicate if there are any unwanted species that 

will be present in the hay bales. Bales of each 

seedlot must be kept separate from other sources 

to prevent mixing. If straw bales are stored 

for any length of time, they must be protected 

from rain. 

276
transitioned in seed production easily, it still requires several years of experience to understand 

how to effi ciently grow native seed. Many seed producers who have moved into growing 

native seed have previous experience growing vegetable or commercial grass seed. These 

seed producers bring great experience and perspective to the native seed industry. Seed 

producers who have had little experience growing seed, often start small with “easier” species 

(i.e., workhorse species) to gain experience. It is important to know the capability of each seed 

producer, and make frequent site visits. Those with a long history of good seed production can 

be contracted for species that are more diffi cult or have not been grown before. It is good to 

request production records, as well as seed tests, to include species, seed yields, seed quality, 

and clients served by the producer. 

Seed Production Timelines – Seed producers are located in many parts of the western United 

States, covering a range of climates aff ecting when seeds are sown and harvested. It is important 

to know the general growing schedule of each seed producer to determine when you will need 

to supply starter seed to the seed producer and when the fi rst shipment of harvested seed can 

be expected. Seed producers from east of the Cascade Mountains might need starter seed 

in the middle of the summer for an August sow, while those west of the Cascades might not 

need it until early fall. Some seed producers wait until the spring to sow seed crops, in which 

case the seed harvest in the fi rst year may be signifi cantly reduced. Depending on the climate, 

seed harvests occur as early as May to as late as August. It is important to specify a date in the 

contract when seed will be delivered, especially if you plan on using the seed in the same year 

it is harvested.

History of Production Fields – Every fi eld will have some amount of residue seeds from previous 

crops which will germinate along with the starter seed. Knowing the history of the fi elds during 

the planning stages helps determine whether these non-crop plants pose a problem for the 

seed production. Noxious weeds or undesirable non-native species are obviously a real concern, 

but many of these species can be roughed out of the seed beds prior to harvesting. Of more 

concern are fi elds where the same native species, but from a diff erent seed source, were grown. 

For example, a fi eld is being prepared for sowing California fescue (Festuca californica) from a 

seed source in the Blue Mountains of northeastern Oregon. The fi eld had previously grown 

California fescue from a seedlot collected west of the Cascades. Since seed from the previous 

fescue crop would germinate in the same bed, the resulting crop would include both seedlots. 

Since the plants from these seedlots would appear almost identical, it would be impossible to 

weed out the plants that came from the previous crop. Even species in the same genera are 

diffi cult to distinguish by untrained weeders and cannot be weeded out of beds. 

Fields that previously produced seed from the same or similar appearing species should be 

evaluated for the risk of seed contamination from previous seed crops. There are measures 

seed producers can take to reduce contamination risks. These include growing non-seed crops 

for several years between seed crops, rotating between grass and forb seed production (forb 

seed is easy to discern from grass seed), and fumigating between seed crops. These strategies 

must be discussed with the seed producers.

Location of Other Seedlots – Equally important to the history of seed production fi elds, is the 

location of adjacent seed crops of the same species. If seedlots of the same species are being 

grown close by, the risk of cross-pollination between crops increases and the genetic integrity 

of the proposed seed crop would potentially be compromised. There can even be crosspollination between similar species. For example, blue wildrye (Elymus glaucus), bottlebrush 

squirreltail (Elymus elymoides), and bluebunch wheatgrass (Pseudoroegneria spicata) are known 

to cross-pollinate. Talk to a local botanist or geneticist about which species can potentially cross 

breed. Seed crops that can cross-pollinate should also be separated by a minimum isolation 

distance. Under most circumstances, the isolation distances should be in accordance with State 

Certifi cation Standards (certifi ed class). These standards can be found at the departments of 

agriculture for each state.

Irrigation System – Many native species must be grown under irrigation to meet the quantities 

of seed specifi ed in the contract. Seed producers that have minimal or no irrigation capacity are 

often unlikely to meet seed production requirements and time frames. Only those species that 

do not require irrigation should be off ered to growers lacking irrigation systems.

Culturing Practices – A review of the culturing practices, which include irrigation, fertilization, 

disease, and insect control, should be done to determine whether they are appropriate for the 

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production of the species being grown. Culturing practices are often written up in propagation 

protocols that can be found at http://www.nativeplantnetwork.org.

Control Measures for Non-Target Species – Specifi c attention must be given to how weeds 

and other non-crop species will be controlled. Typical measures include 1) the use of herbicides 

prior to sowing and after the crop has been established, and 2) hand weeding of non-target 

species. The most important period of weed control is just prior to seed harvest because of the 

importance of eliminating potential non-target seed before seed harvest.

Seed Harvest Methods – Most seed harvests are carried out with specialized equipment 

that detaches seed from the stock, separates it from plant and soil debris, and collects it into 

storage containers (Figure 10.67). It is important to know the seed harvesting equipment that 

will be used for each species and how it will be cleaned between seedlot crops to prevent the 

possibility of seed contamination. 

Species with indeterminate infl orescences (seeds that ripen on the seed stock all summer long) 

must be hand collected more than once in the summer. Periodic seed harvests of these species 

must be planned so that the full range of seed can be collected. The seed producer should 

address how these species will be harvested to obtain the maximum seed yield.

Seed Cleaning, Packaging, and Labeling – After seed is harvested, it must be dried and 

further cleaned. Seeds are air dried (Figure 10.68) or placed in a forced air drying system. Seeds 

are then extracted and cleaned. Awns and fl ower parts are removed and dirt, stems, and other 

debris are separated from the bulk seed. Understanding the cleaning operation is important 

because viable seeds can be damaged or discarded during this process. 

Dry cleaned seed should be packaged in “breathable” woven poly bags at uniform weights. 

Industry standards are 25 or 50 lb bags. Bags of seed must be clearly identifi ed (labeled by 

stencil or permanent marking pens, with characters at least 1 inch in size) with the Government’s 

source seedlot identifi cation. In addition, all bags should have an affi xed tag stating the species 

name (scientifi c and common), seedlot identifi cation, % germination, % purity (including 

other crop seed, weed seed, and noxious weeds), date of seed test, and seed producer’s name. 

Additional labeling information may be requested, such as project name, National Forest or 

BLM offi ce, or seed owner name. 

Seed Testing and Acceptance – The contract must state the minimum acceptable standards for 

each species and seedlot. Acceptance and payment should be based on meeting the standards 

set for:

 · Germination,

 · Purity,

 · Weeds, and

 · Moisture content.

Seed testing is typically the responsibility of the contractor. Seed samples used for testing and 

contract performance must be taken by a certifi cation agency representative or the contract 

inspector. Samples must be tested by a state certifi ed seed laboratory (See Section 10.2.1.7). 

Seed test results must be identifi ed by the seed source identifi cation and task order number. 

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Figure 10.67 – Seed harvesting 

equipment varies by seed producers 

and species being harvested. 

Discuss with the seed producer 

how each species will be harvested 

and see that equipment is cleaned 

between seedlots.

278
Test results must be satisfactory to the Government before fi nal acceptance of the seed 

is made. 

Establishing minimum germination and purity rates can be based on averages obtained from 

commonly produced species shown in Table 10.14 or through discussion with seed extractory 

managers. The contract should address what actions the contractor can take to increase 

either germination or purity, if these rates fall below the standards. Lower purity rates can be 

accepted if seed will be used in a hydroseeder (See Section 10.3.2). A tetrazolium test (TZ) may 

be made in lieu of a germination test for a seed viability test depending on time constraints and 

species involved. All-State Noxious Weed examinations are required and if any of these species 

are present, then the seedlot is either rejected or recleaned. Seed moisture test must also be 

conducted and seed must not exceed 10% moisture.

10.2.4.6 Administer Contract

Seed producers are required to maintain adequate records to allow the Government to 

monitor contract progress. Records should include information and dates of fi eld preparation, 

seed sowing, fi eld treatments, fertilization, seed harvest, cleaning, storage, seed yields, and 

any other activity relating to seed production. It is a good practice to make contact either by 

phone or by visiting the seed producers two to three times a year to go over the progress of 

the contract. The best time of year for fi eld visits is just prior to or during seed harvest. A visit 

or phone contact in fall is important to discuss the potential of keeping seedlots additional 

years. Unless it is stated in the contract, seedlots are likely to be plowed under once the seed 

orders have been met. Visiting in the late summer or fall is also a good time to observe the seed 

extraction and cleaning processes.

During these visits, it is important to note the condition of the seedlots and how they are being 

identifi ed throughout the process; are there clear labels stating the seedlot identifi cation in the 

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Figure 10.68 – Seed is harvested and 

dried prior to cleaning and storage. This 

photograph shows a recently harvested 

seedlot in drying trays prior to being 

set on a forced air drier. Seed ID tags 

are attached to the side of each seed 

drying bin.

Figure 10.69 – It is important to visit 

seed producers to assess isolation 

distances, noxious weeds, culturing 

practices (e.g., irrigation, fertilization), 

and expected seed yields. The best 

period to visit is during seed ripening 

and seed harvest.

279
fi eld, during drying, extraction, and storage? Are seed harvest and extraction equipment being 

thoroughly cleaned between seedlots or are there remnant seeds remaining in the equipment 

that can contaminate the next seedlot being processed? Note the condition of the fi elds prior 

to seed harvest; are the fi elds weedy and will there be a fi nal weeding before harvest? Are seeds 

being handled with care or are they roughly handled? 

A good working relationship with the seed producer is essential in meeting the overall seed 

increase objectives. It should be realized that some factors, such as weather, are beyond the 

control of seed producers, and on some years seed harvests will fall short of the minimum 

amounts stated in the contract. Good communications with the seed producer will alert you 

to crop failures or fall down in orders as soon as they occur so that alternative measures can be 

taken. An inventory of the number of acres in each seedlot and the condition of the crop should 

be supplied by the contractor upon request.

10.2.4.7 Store Seed

Seeds can remain viable in storage for many years after harvest. How well seeds keep depends 

on the moisture content of the seed, the quality of the seed being stored, and the storage 

conditions (temperature and humidity). Riley (2006) found that there was minimal reduction 

of seed viability in granary storage after three years for mountain brome (Bromus marginatus) 

and Idaho fescue (Festuca idahoensis) (Figure 10.70). Seeds typically store poorly when seed 

quality is low or seed moisture content is above 10 percent. If seedlots are stored for more than 

a couple of years, it is important to periodically test the seed for germination.

Granary Storage – Most seedlots are stored for short periods of time before they are used 

on projects (usually less than fi ve years). For this reason, granary storage is the most common 

and economical form of seed storage. Granary storage unit are enclosed rooms sheltered from 

rainfall and temperature extremes. They are typically insulated and protected from rodent and 

insects. Many granary storage units are tree coolers that have been reconfi gured for this use. 

While seedlots can store for long periods, low quality seed should be used fi rst because it is 

more likely that this seed will loose viability in storage, than high quality seed.

Freezer Storage – Freezer storage is usually reserved for seedlots that will be stored for many 

years. Conifer and shrub seeds as well as forb and grass wild seed collections are usually stored 

under these conditions, whereas bulk grass and forb seeds typically are not.

10.2.5 NURSERY CUTTING PRODUCTION

10.2.5.1 Introduction

Obtaining cutting materials in the wild for restoration and bioengineering applications can be 

a diffi cult and expensive task, especially if populations of parent material are small or access 

is limited. Native plant nurseries can be an alternative source of a variety of woody cuttings. 

Understanding how nurseries establish and manage “stooling beds” can be a great help to 

Roadside revegetation specialists and project engineers. 

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Figure 10.70 – Properly 

cleaned, packaged, and dried 

seed can remain viable for 

many years under acceptable 

granary storage conditions. 

Seed germination for two 

Umatilla National Forest 

seedlots did not signifi cantly 

decrease in storage after three 

years as shown in this graph 

(Riley 2006).

2002

100

80

60

40

% Viable Seeds (TZ Test)

20

0

Mountain Brome Idaho Fescue

2005

2002 2005

280
10.2.5.2 What are Stooling Beds?

“Mother plants” are established in nurseries for the sole purpose of providing a ready source of 

cuttings. Stooling beds are hedge-like rows of mother plants that are established in bareroot 

nurseries or in vacant fi elds adjacent to container nurseries (Figure 10.71A). 

Stooling beds take advantage of the ability of many broadleaved woody plants to sprout 

profusely from the base after being cut off just above the root crown. Plants remain in the juvenile 

state, which means they have a higher tendency to sprout and produce roots. Once stooling 

beds are established, annual cutting ensures that juvenility can be prolonged indefi nitely.

Stooling beds allow the effi cient collection of dormant hardwood cuttings during the winter 

when it may be diffi cult or impossible to make fi eld collections (Figure 10.71B). Because they 

are located at nurseries, the beds can be irrigated and cultured; processing and storing the 

cuttings is also much more effi cient and cost-eff ective. Stooling beds have several advantages 

over wild collected cuttings.

Maintaining Genetic and Sexual Diversity – It is much easier to correctly identify diff erent 

plant species and ecotypes from labeled stooling beds as compared to wild collections. For 

example, willows often grow together along streams and can be diffi cult to identify during the 

winter dormant season. Stooling beds off er the ability to produce a large number of cuttings of 

unique species or ecotypes quickly and easily. 

Many government nurseries have established stooling beds of the species and ecotypes 

that are adapted to their local area and can thus be a potential source of cutting material for 

private growers or revegetation specialists. Private native plant nurseries are also establishing 

stooling beds of desirable species for their local areas, and several are specializing in riparian 

and wetland species. For specifi c revegetation projects, however, the odds of a nursery having 

existing stooling beds of the proper species and local ecotype are low. Therefore, collecting 

cuttings and establishing stooling beds should be done early in the planning process so a good 

supply of cuttings will be available when needed. 

Some plants, such as willows and cottonwoods, are either male or female, which can create 

a serious problem in restoration (Landis and others 2003). If a balanced mixture of male and 

female plants is not collected from the project site, the resultant stooling beds will not produce 

both male and female cuttings. When working with dioecious plants, the sexual identity of 

potential mother plants must be determined prior to collection (See Section 10.2.2, Collecting 

Wild Cuttings). 

Producing Healthy and Vigorous Cuttings – One of the most practical advantages of 

establishing stooling beds in nurseries is that the cuttings are often healthier and more 

vigorous than those collected from the project site. Willows are host to many insects and 

fungal pests, such as galls and cankers (Figure 10.72). They are also subject to animal browsing. 

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Figure 10.71 – Stooling beds (A) are an effi cient way of ensuring that a ready supply of 

hardwood cuttings of the proper species and source are available (B).

A B

281
These factors can signifi cantly lower the quality of wild-collected cuttings. For example, on 

a riparian restoration project in Idaho, cuttings were collected from heavily browsed willows 

on the project site and then planted in nursery beds to produce rooted cuttings. The yield 

of shippable plants was low and these wild-collected cuttings rooted poorly (<50%) when 

outplanted. These failures increased production costs and threatened the project’s replanting 

schedule. Subsequently, about 150 rooted cuttings from the fi rst nursery crop were used to start 

a stooling bed. The following year, harvesting just half of the stooling bed yielded more than 

6,000 healthy cuttings. Cuttings from the stooling beds rooted at over 99%, thereby lowering 

establishment costs and keeping the project on schedule (Dumroese and others 1998). 

Reducing Costs – It might seem that collecting cuttings in the wild would be the least expensive 

means of obtaining cutting materials. This is not necessarily the case. Ineffi ciencies of driving 

to remote locations, pulling cutting materials to road ways, using make-shift cutting practices, 

and working under severe winter conditions all add up to high costs per cutting.

10.2.5.3 Select Species Suitable for Stooling Beds

Poplars, cottonwoods, and willows are the species most often used in stooling beds. It should 

not be assumed, however, that all species of the willow family are good candidates for stooling 

beds. Some species have growth characteristics that reduce their potential. For example, 

trials at the Colorado State Forest Service Nursery in Fort Collins have shown that narrowleaf 

cottonwood (Populus angustifolia) and narrowleaf willow (Salix exigua) do not “stool” well and 

must be propagated by other methods (Grubb 2007). 

There is great potential for using other woody species that have the propensity to sprout 

and form roots easily. For example, redosier dogwood (Cornus sericea) is commonly grown in 

stooling blocks and used as a source of cuttings for restoration sites. Outplanting success is 

higher than with wild cuttings collected on the project site, and has ranged from 50% to 90% 

(Hoag 2007). In North Dakota, twinberry honeysuckle (Lonicera involucrata) is being investigated 

(Morgenson 2007). Native species that root easily from hardwood cuttings have the potential to 

be grown in stooling beds to generate cuttings. Species that have inherent deep seed dormancy 

characteristics, such as snowberry, honeysuckle, elderberry, and some species of currants, could 

be more easily propagated in the nursery using stooling beds than sowing seeds to produce 

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Figure 10.72 – Stooling beds can be cultured to prevent the occurrence of insect galls (A) and 

fungus cankers, such as Cytospora spp (B).

A B

282
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seedlings. Species that have consistently low seed viability, such as mock orange and ninebark 

(Physocarpus spp.), may also be produced more economically in stooling beds.

The Plant Materials Centers of the USDA Natural Resources Conservation Service identifi ed the 

potential of a wide variety of woody native plants that would be suitable for stooling beds 

(Table 10.15). For example, Crowder and Darris (1999) discuss which plants are suitable in 

the Pacifi c Northwest and provide a wealth of information on the installation and culture of 

stooling beds. 

Darris (2002) performed extensive greenhouse and fi eld trials to test the potential of several 

woody plants for live stake applications. Common snowberry (Symphoricarpos albus), 

salmonberry (Rubus spectabilis), Pacifi c ninebark (Physocarpus capitatus), and twinberry 

honeysuckle (Lonicera involucrata) have proven to be eff ective as live stakes for soil 

bioengineering in the Pacifi c Northwest. Notably, several have proven to be superior to willow 

Table 10.15 – Native woody plants of the Pacifi c Northwest with potential for propagation in 

stooling beds.

Plant Species Rooting 

Ability

Growth Rate Establishment 

Success

( 1 = Poor, 

5 = Good)

Scientifi c Name Common 

Name

Baccharis 

pilularis

Coyotebrush Fair to Good Moderate 3

Cornus sericea Redosier 

dogwood

Good Fast 3

Oemleria 

cerasiformis 

Indian plum Poor to Good Moderate 1

Physocarpus 

capitatus

Pacifi c 

ninebark

Good to 

Very Good

Moderate 

to Fast

4

Philadelphus 

lewisii

Lewis’ mock 

orange

Fair Moderate 1

Populus 

trichocarpa

Black 

cottonwood

Fair to Very 

Good

Very Fast 3

Rosa woodsii Woods’ rose Poor to Fair Moderate 

to Fast

1

Salix 

amygdaloides

Peachleaf 

willow

Excellent Very fast 5

Salix exigua Narrowleaf 

willow

Very Good Fast 4

Salix lasiolepis Arroyo 

willow

Excellent Very Fast 5

Salix scouleriana Scouler’s 

willow

Good to 

Very Good

Very Fast 4

Spiraea douglasii Rose spirea Very Good Fast 4

Symphoricarpos 

albus

Common 

snowberry

Very Good Fast 4

* = modifi ed from Crowder and Darris (1999)

283
on some sites, such as salmonberry in wet, shaded environments and snowberry on drier, 

exposed locations.

10.2.5.4 Select the Type of Cutting Material

Several diff erent types of cutting materials can be collected from stooling beds. Nurseries use 

small propagation cuttings to start their own bareroot or container plants. Stooling beds can 

also provide several types of unrooted cuttings used in restoration (Figure 10.73). 

Live Stakes – Live stakes are so named because, in addition to providing stability on restoration 

sites, they are expected to root and sprout after installation (See Section 10.3.3.2, Live Stakes). 

Because they are often pounded into the ground, live stakes are cut from relatively straight 

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Figure 10.73 – Several types of hardwood cuttings can be obtained from stooling beds, 

including cuttings for propagation at the nursery or live stakes and branched cuttings for 

restoration projects. Note that larger plant materials require extra time to produce.

18 to 24 inches

4 to 15 feet

6 to 8 feet

1 to 3 inches

0.5 to 2 inches

3 to 6 inches

A – Live Stake

B – Branched Cutting

C – Pole Cutting

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sections of second- or third-year wood. Live stakes are typically 18 to 24 inches in length and 

from 1 to 3 inches in diameter (Figure 10.73A). Depending on the plant species, it can take 2 to 

4 years for a stooling bed to produce large enough branches for live stakes. Some of the smaller 

willow species will never grow large enough.

Branched Cuttings – Bioengineering practices, such as live fascines, vertical bundles, brush 

layers, and pole drains (See Section 10.3.3.3, Live Brush Layers and Section 10.3.3.4, Live Fascines) 

require a large number of branched hardwood cuttings (Hoag and Landis 2001). The size of 

this material ranges from 0.5 to 2 inches in stem diameter and 4 to 15 feet in length (Figure 

10.73B). Stooling beds may take 2 or more years to produce signifi cant numbers of harvestable 

branched cuttings. 

Pole Cuttings – Pole cuttings (Figure 10.73C) are large diameter (3- to 6-inch) main stems that 

have all side branches with the top 1 to 2 feet of stem removed. They are used in restoration 

projects where stability is a main concern. Because of the large size of the plant material 

necessary for pole cuttings, nursery stooling beds are ideal. Larger trees, such as cottonwoods 

and tree-sized willows (e.g., Goodding’s willow [Salix gooddingii]), have primarily been used 

for pole cuttings. Other large woody plants with the potential to sprout may also prove to be 

viable material (Dreesen and Harrington 1997). 

10.2.5.5 Develop Timeline

Obtaining cutting materials from established stooling beds takes between 1 and 5 years, 

depending on the type of material. A minimum of one year is necessary to produce branched 

cuttings; 2 to 4 years to produce live stakes; and pole cutting may require over 4 years (Figure 

10.74). In the planning stages of the revegetation project, the number, type, and species of 

cuttings needed for the project must be determined. Procedures for making these calculations 

are outlined in Section 10.2.2.6, Determine Cutting Needs. Nurseries or government facilities 

that specialize in stooling bed production must be contacted to see if they will establish stooling 

beds for your project. The managers of these facilities will inform you of costs and the time 

frame for meeting your orders. While there will be some cutting materials produced in the fi rst 

year, full production of stooling beds does not happen until several years after installation. 

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Figure 10.74 – Obtaining cutting materials from stooling beds can take up to four years, 

depending on the type of material requested. Branched cuttings can be obtained from stooling 

beds after the fi rst growing season, while live stakes can take from 2 to 4 years. Pole cuttings can 

take even longer. The following is a timeline for producing branched cuttings and some smaller 

live stakes. Add several years for large stakes and some poles.

Store and install cuttings

Determine cutting needs

Cutting Production

Tasks

Year

Obtain“starter”material

Develop & award contract

Work with growers

-3 -2 -1 0 1

Road Construction Install Cuttings

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Most stooling beds are started from cuttings taken from the wild. The sources of starter material 

must be located in the fi eld during the summer or fall prior to installation of the beds. The 

sexual identity of dioecious plants must be determined during the appropriate season prior 

to collection. Section 10.2.2.3, Locate Cutting Areas, gives an outline of the steps necessary 

to obtain starter material. The nursery managers will tell you the number of feet of starter 

material, the quality of the wild collections (age, size, condition), and packaging and shipping 

methods necessary to meet the order. Wild cuttings are collected when the leaves are off the 

plants. Depending on the climate of the site, collections can begin in mid to late fall and end 

from late winter to mid spring. Wild cuttings are usually sent immediately to the nursery where 

they are prepared for installing in stooling beds. Most stooling beds are started directly from 

cuttings that are stuck in the spring. Cuttings root quickly in the spring and, with irrigation and 

fertilization, grow into large plants by the end of the summer. The following winter, the beds are 

ready for harvest. Since stooling beds are relatively uniform, the material can be harvested and 

processed in a production-oriented manner. Cutting materials are cut to your specifi cations 

and stored in either freezer or cold storage facilities until you request delivery. 

Developing stooling beds is a long-term investment. While they often take several years to 

fully establish, stooling beds can remain productive for many years depending on species, 

ecotype, nursery cultural practices, and pest management. For cottonwoods, stooling beds 

typically remain productive for 4 to 8 years, after which vigor and productivity start to decline. 

However, other nurseries have maintained stooling beds of willow and cottonwood for 12 to 

15 years without decreases in vigor. Cytospora canker, caused by fungi of the genus Cytospora

spp (Figure 10.72B), is a particularly serious pest of all Salicaceae and, because it is transmitted 

and thrives in wounded stem tissue, can ruin a productive stooling bed. The productivity and 

longevity of a stooling bed is a direct function of the amount of care given them. Since stooling 

beds are an investment with long-term payoff s, fi nding local partners (watershed councils, 

Forest Service, BLM, state and county land managers), who can utilize these beds after the 

needs of your project have been met can be a service to the local community.

10.2.6 NURSERY PLANT PRODUCTION

10.2.6.1 Introduction

Woody plants are critically important because they quickly provide vertical structure and 

aesthetic relief on roadside revegetation projects. When planted within areas seeded with 

grasses and forbs, trees and shrubs provide the essential matrix of a successful revegetation 

project. Direct seeding is rarely used to establish woody plants on restoration projects because 

they are often slow to germinate and take several years to become established. Depending on 

site characteristics, many sizes of nursery stock can be used, but large plants are favored by 

revegetation specialists because they establish quickly and dominate the site. Their physical 

size and deep roots allow them to quickly access deep soil moisture, and their expansive 

root systems help stabilize soils. In addition to providing wind protection and shade to lower 

growing vegetation, trees and large shrubs provide habitat for insects, birds, and other animals 

and can greatly accelerate the development of a sustainable plant community.

Grasses and forbs establish quickly and easily from seeds, so they are not commonly grown in 

nurseries. However, nursery stock is warranted under certain circumstances:

 · Suffi cient quantities of grass and forb seeds are rare or hard to collect.

 · Increasing grass and forb seeds by seed growers is difficult or excessively expensive.

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Figure 10.75 – Steps 2 through 4 of the 

Target Plant Concept are very useful 

when ordering nursery stock (adapted 

from Landis and Dumroese 2006). 2. Type of Plant Material

5. Timing of Outplanting Window

6. Outplanting Tools and Techniques

3. Genetic Considerations

4. Limiting Factors on 

 Outplanting Site

1. Objectives of Outplanting Project

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 · Establishing grasses and forbs is diffi cult on some sites.

 · Restoring threatened or sensitive species is a high priority.

 · Nursery stock is more effective in restoring wetlands.

 · Installing nursery stock is the best and fastest way to achieve a desired 

plant composition.

 · Aggressive weeds are a serious problem.

This guide outlines the steps needed to obtain quality seedlings, transplants, or rooted cuttings 

from native plant nurseries. Typically, it takes one to two years to grow nursery plants, so the 

revegetation specialist must develop growing contracts and establish timelines several years 

in advance. 

10.2.6.2 The Target Plant Approach

The target plant concept (Figure 10.75) is one method to optimize the use of native plant 

materials to ensure successful revegetation of the site. The fi rst two steps in the process were 

covered during planning (See Section 6.4). Consideration of the plant material that would 

best meet the project objectives for a given site may lead to the decision to use nursery stock. 

Nursery stocktype, genetic considerations, and site factors limiting to plant establishment 

must then be discussed prior to ordering nursery plant materials. These 3 topics will be covered 

in detail in the following sections. Outplanting windows and outplanting techniques will be 

discussed in Section 10.3.4, Installing Plants.

Stocktype – The term “stocktype” refers to the various products that a native plant nursery can 

provide (Inset 10.17). In a broad sense, it includes seeds, which are discussed in Section 10.2.4. 

The oldest nursery stocktypes are bareroot seedlings and transplants. However, container plants 

are usually most suitable for roadside revegetation projects. Container nurseries are currently 

producing a wide variety of stocktypes that include seedlings, transplants, and rooted cuttings. 

Although project objectives and planting site characteristics should be primary considerations, 

the choice of container stocktype is more often defi ned by price. The price of container stock is 

based on the cost of materials and, more important, nursery production space and time. A unit 

area of greenhouse bench space or outdoor growing compound is a fi xed cost, but the number 

of months or years to grow the plants to shippable size add to the stock price. Although selling 

prices for each container stocktype are set by tradition and market factors, older and larger 

plants will cost more. 

Genetic Considerations – Genetics are a key factor in the target plant concept (Figure 10.75), 

and two factors must be considered: local adaptation, and genetic and sexual diversity.

“Seed source” is an idea familiar to all foresters and restoration specialists. Plants are adapted to 

local conditions. If native species can be propagated from seeds, these seeds should always be 

collected within the local “seed zone.” The seed zone is a three-dimensional geographic area 

that is relatively similar in climate and soil type. 

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Inset 10.17 – Native Plant Nurseries Produce Two Main Stocktypes

Bareroot stock is grown in native soil in open fi elds and harvested without soil around 

the roots. Because of the added care needed and increased potential for transplant 

shock on highly disturbed sites, bareroot plants are not usually recommended for 

roadside revegetation.

Container stock is grown in artifi cial growing media in a controlled environment, such as a 

greenhouse, and their root systems form cohesive plugs when harvested.

Nursery-grown plants are grown as:

 · Seedlings are plants started from seeds. 

 · Rooted cuttings are plants grown from vegetative cuttings.

 · Transplants have been physically removed from the seedbed or container and 

replanted in a transplant bed or larger container for additional growth. 

287
Seed source aff ects plant establishment through growth rate and cold tolerance. In general, 

plants grown from seeds collected from higher latitudes or elevations will grow slower but tend 

to be more cold hardy during the winter than those grown from seeds from lower elevations 

or more southern latitudes (St Clair and Johnson 2003). The majority of seed zone research 

has focused on conifers in the Pacifi c Northwest. The same concepts can apply to other native 

species. Nurseries sow and culture plants according to seed zones. It would therefore be 

prudent to use nursery seedlings or cuttings from the same geographic zone and elevation in 

which it will be outplanted. 

Target plants should also represent the genetic and sexual diversity present on the outplanting 

site. To maximize genetic diversity in the nursery plants, seeds and cuttings should be collected 

from as many diff erent plants as possible. Cuttings must be collected near the outplanting site to 

assure they are properly adapted. Additional considerations are necessary for dioecious plants, 

such as Salix spp. and Populus spp., because all progeny produced by vegetative propagation 

will have the same sex as the source plant. Therefore, when collecting cuttings at the project 

site, care must be taken to ensure that male and female plants are equally represented.

Of course, collecting costs must be kept within reason, so the number of seeds or cuttings 

collected must be a compromise. Guinon (1993) provides an excellent discussion of all factors 

involved in preserving biodiversity when collecting seeds or cuttings, and suggests a general 

guideline of 50 to 100 donor plants.

Site Limiting Factors – The fourth aspect of the target plant concept (Figure 10.75) is based 

on the ecological “principle of limiting factors,” which states that any biological process will 

be limited by that factor present in the least amount. Each planting site must be evaluated to 

identify the environmental factors most limiting to plant survival and growth (See Chapter 5) 

as this information is critical to deciding on the proper nursery stocktype. Large container trees 

with a deep root system typically survive better and establish faster, but woody shrubs and 

other plants in smaller containers can fi ll other needs. 

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Figure 10.76 – Obtaining nursery-grown plants often requires two to three years of advance 

planning. This timeline can be shorted by up to a year if “starter” plant materials, like willow 

cuttings or seedlings for transplanting, are available. Certain woody plants require long seed 

treatments or grow slowly so timetables must be adjusted accordingly.

Determine plant needs

Plant Production

Tasks

Year

Obtain“starter”plant materials

Develop and award contract

Work with nursery

Develop planting plan

Store plants

Transport plants to site

-3 -2 -1 0 1

Road Construction Plant

288
Restoration sites pose interesting challenges when evaluating limiting factors. Road construction 

or decommission typically creates compacted soils that have been severely altered in texture, 

stability, nutrient status, and so on from their natural state. 

In addition to challenging physical soil characteristics, the biological component of roadside 

planting sites has been severely altered or even destroyed. A variety of mitigating measures 

may be necessary prior to outplanting. Benefi cial soil microorganisms, such as mycorrhizal fungi 

and nitrogen-fi xing bacteria, provide their host plants with many benefi ts including better 

water and mineral nutrient uptake. Plants destined for these sites should be inoculated with 

the appropriate symbiont before outplanting (See Section 10.1.7 for a complete discussion).

10.2.6.3 Develop Timelines

Obtaining some nursery stocktypes can take a considerable amount of lead time and planning. 

Although most native plant nurseries carry a wide variety of species, it is unlikely they would 

have plants that are genetically suitable for a specifi c project. Therefore, “source-identifi ed” 

native plants must usually be grown by contract. The large nursery stocktypes that will survive 

and grow on challenging restoration sites typically require several years (Figure 10.76). It is 

therefore necessary to develop contracts that will assure that the correct genetic material is 

being propagated and that the resulting plants are of the highest quality that will survive and 

grow when planted on the revegetation site. 

Project plant needs are determined early in the revegetation planning stages, including the 

number of plants, types of species, and size of plants. From the list of species, seed sources 

or “starter” plant material sources are located from suppliers or collected in the wild. This can 

typically take at least a year. Several years before the construction site is ready for planting, a 

contract for growing plants is developed and awarded. Once awarded, seeds and “starter” plant 

materials are sent to the nursery so that sowing, transplanting, or sticking can begin promptly. 

The growing time for large container stock can extend from 1 to 2 years, depending on the 

species. The nursery will take a fi nal seedling inventory during the middle of the fi nal growing 

season. At this time, a planting plan can be developed. Road construction will be moving into 

its fi nal stage and the planting plan can be tailored to specifi c on-site conditions. Including 

lifting, storage, and transporting plant materials, the whole process, from start to fi nish, takes 

two to three years.

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Figure 10.77 – A spreadsheet can be used to determine how many plants must be ordered for 

each species. Each revegetation unit should have separate calculations, since the units will have 

diff erent survival rates, species mixes, and plant spacing.

A Planting area: 0.75 acre Area that will be planted

I 340 plants Number of PIPO to order 

H 20 Percent of total established plants composed of AMAL2

E * F / 100 =

J E * G / 100 = 204 plants Number of POTR5 to order

K E * H / 100 = 136 plants Number of AMAL2 to order 

G 30 %

%

Percent of total established plants composed of POTR5

Serviceberry (AMAL2)

F 50 % Percent of total established plants composed of PIPO

Quaking aspen (POTR5)

E 681 plants Number of nursery plants that need to be planted

Ponderosa pine (PIPO)

Species Mix

D * (100 / C) =

D 510 plants Desired number of established plants after one 

growing season (A * 43,560) / (B * B) =

C 75 % Percent of seedlings that survive after one 

growing season Avg. survival potential:

B Target plant spacing: 8 feet Desired distance between established plants

289
10.2.6.4 Determine Plant Needs

Early in the planning stages, a general idea of plant needs is developed based on the desired 

future condition for each revegetation unit. The information required to determine the 

quantities for each revegetation unit includes:

 · Area to plant,

 · Plant spacing (density),

 · Survival potential, and

 · Species mix.

Using calculations similar to those presented in Figure 10.77, an estimate of the number of 

seedlings to order from nurseries can be determined. Calculations should be performed for 

each revegetation unit, since species mix, plant spacing, and survival will change considerably 

between units.

Planting Area – Summarize the acreage of all planting areas within each revegetation unit.

Target Plant Spacing – The target plant spacing is the desired distance between established 

plants. The spacing or density of established plants is an estimate that should be based on 

the site productivity and project objectives. A review of the reference sites can be a guide to 

determining the densities and species mix a site will support. Be sure to note how the diff erent 

plant species are naturally spaced on each reference site. Some grasses and forbs exhibit 

uniform spacing but many woody plants have a more random or clumped pattern (See Figure 

10.119 in Section 10.3.4, Installing Plants, for more discussion).

For example, an undisturbed reference site description shows that an average density for an 

established stand of trees is 500 trees/ac, with a species mix of 80% ponderosa pine and 20% 

quaking aspen (Density can be converted to plant spacing by taking the square root of 43,560 

divided by plants per acre).The selection of species often determines the planting densities. 

Shrubs, for instance, grow at much closer spacing than trees, and this should be taken into 

consideration when species mixes are determined for a revegetation unit. 

Revegetation unit objectives often require higher plant densities than typically occur on 

reference sites. Quick visual screening as the overriding objective will require high-density 

planting. Selecting a higher plant density than typically occurs in the project area should be 

done with some projection of how the area will appear many years later. High-density planting 

can create overstocked stands of trees within ten or twenty years of planting (Figure 10.78). 

Overly dense stands often lead to stressed trees and high fi re hazard conditions, and might 

require some thinning at a later in time. 

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Figure 10.78 – Determining plant spacing should be based on short- and long-term objectives. 

Where the short-term objective is quick visual screening and site stabilization, high density 

plantings of 1,500 trees/ac (A) will produce the short-term desired outcome. These trees may 

need to be thinned to reduce competition to avoid creating an unhealthy stand of trees with a 

high fi re risk. Reducing tree densities to 250 trees per acre will produce a mature stand of trees 

similar to (B). Planting at these lower densities will reduce the need for thinning, but tree cover 

will take longer to dominate the site.

A B

290
Survival Potential – The survival potential is an estimate of the percentage of planted 

seedlings that will survive and become established. There are many factors that determine how 

well nursery-grown plants will survive after outplanting. Factors that you can control include:

 · Selection of appropriate species and seed source for the site,

 · Quality of nursery plants,

 · Appropriate storage and transportation conditions, and 

 · Care in stock handling and planting. 

High rates of plant mortality are usually due to an oversight or neglect of one or more of these 

factors. Projects with high plant mortality are an indication of poor planning or implementation; 

in other words, you have missed the mark on one of these factors. However, aiming for 100% 

survival is often unreasonable because of the high associated costs. Most projects should aim 

for a plant establishment rate of 85% to 90%, but plan for 75%. 

Species Mix – Good survival and establishment of plants fundamentally rests on selecting the 

most appropriate species from locally adapted seed sources. Selecting the species mix for each 

revegetation unit should be based on an evaluation of disturbed and undisturbed reference 

site descriptions, which includes an understanding of the site limiting factors that will aff ect 

plant survival. 

10.2.6.5 Select Stocktypes

Plants are grown, or cultured, in a variety of ways – indoors or outdoors, in native soil or 

artifi cial media, for several months or up to several years. The nursery industry defi nes how 

a plant is grown and its size, or morphology, in groups called “stocktypes.” Although there is 

no standard terminology for describing the variety of possible stocktypes (Landis and others 

1993), individual stocktypes can be defi ned by:

 · Propagation environment (bareroot or container),

 · Years in the nursery, and

 · Size or shape of the container for container stock.

Propagation Environment – Plants are grown either in containers (container) or in native soil 

in open fi elds (bareroot). Bareroot stocktypes are harvested and packaged without soil around 

the roots, whereas the root systems of container plants are held together in a plug of rooting 

media. In many cases, container seedlings can be planted at any time of the year if appropriate 

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Figure 10.79 – Native 

plants have diff ering 

growth habits and rates, 

so it is important to 

match container size 

with species growth 

characteristics. Shaded 

blocks represent 

recommended container 

sizes for each species 

type in years 1, 2, and 3.

Evergreen TreesDeciduous TreesShrubs – fast growingShrubs – slow growingEvergreen TreesDeciduous TreesShrubs – fast growingShrubs – slow growingEvergreen TreesShrubs – slow growing

Container

Sizes

Years in Containers

Cubic

Inch Gallon

10-20

1 23

30

60

115

230

460

925

1/8

1/4

1/2

1

2

4 291
planting methods are used. Bareroot seedlings, on the other hand, are typically lifted in the 

winter months and held in storage for several months, limiting the planting window from early 

winter through later spring. Container plants can be grown in large pots for more than two 

years to very large sizes. Bareroot plants are limited to the depth of the growing beds, which 

is typically less than 12 inches. Depending on the species, bareroot plants can usually be held 

in beds for only 1 to 2 years. While container plants have many advantages over bareroots, 

bareroot seedlings are often much less expensive to purchase and plant. However, for most 

roadside revegetation sites, we recommend container stock.

Container Size – The size and age of a nursery-grown plant is controlled by the size of the 

container. Typically, the larger the container, the larger the plant and the longer it takes for 

roots to fi ll the container. In Figure 10.79, plants are grouped into broad categories based on 

how fast they typically fi ll out various container sizes. Many deciduous tree species, which 

include willows, cottonwood, maples, alders, and ash, tend to be very fast growing species and 

can fi ll out a range of container sizes in just one growing season. Conifer species (fi rs, pines, 

cedars, and hemlocks) will fi ll smaller containers the fi rst year and can be transplanted into 

larger containers for another one or two growing seasons. Faster-growing shrub species 

(ceanothus, bitterbrush, mountain mahogany) are often grown in small containers in the spring 

and transplanted into larger containers several months later. They will fi ll a 1/8 to 1/2 gallon in 

one growing season. Slower growing shrub species must remain in the smaller cells for a full 

growing season before transplanting. 

Container Design – Container shape is also an important consideration in stocktype selection 

because it determines how easily the root plug is extracted from a container, the degree of root 

spiraling, what planting methods are used, and ease of handling. The depth and taper of the 

container walls govern how easily a root plug can be extracted from its container. Generally, 

the greater the taper, the easier a root plug can be extracted from its container. Taper becomes 

more critical as container walls become longer with respect to the diameter of the opening. 

Straight-walled “tall pots,” made from PVC pipe, are very long in comparison to the diameter 

of the opening. Root plugs from this container are diffi cult to extract without the placement 

of Vexar tubing inside the container. Pulling the Vexar tubing during extraction brings out the 

entire root plug without undue stress 

to the stem or root system. Other 

nurseries off er tall pots with the PVC 

pipe cut in half lengthwise and held 

together with electrical ties. Before 

planting, the ties are cut, which allows 

easy access to the root system.

Several container design features 

aff ect root development and plant 

quality. When plant roots grow out 

and hit the sides of the container, 

they often grow downward in a 

spiral pattern. When roots reach the 

bottom holes, they should “air prune.” 

In poorly designed containers, the 

circling roots will eventually form a 

tight mesh which, after outplanting, 

can continue to circle and “strangle” 

the plant. Most containers have 

vertical ribs that guide roots down 

the sides of the container walls to 

prevent root spiraling. Some smaller 

containers feature copper coating on 

their walls to chemically prune the 

roots as they grow. Other container 

walls have vertical air slits which air 

prune the roots. When container 

roots are so cultured, the root system 

is more fi brous with more root tips. 

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Figure 10.80 – Nurseries can produce plants in 

all shapes and sizes. The best stocktype for your 

project will depend on site conditions and time and 

method of planting. Short One Treepot Tall One Treepot

2 Gallon Treepot

PVC Tallpot

Ball-and-Burlap

RL Supercell

D16 Deepot

292
Root condition is a critical factor to discuss at the time that growing contracts are being 

developed. Roots that have excessive spiral growth must be pruned before they are planted 

(See Figure 10.128 in Section 10.3.4). This is most easily done at the nursery during harvesting. 

This extra processing step must be stipulated in the growing contract. 

Matching Nursery Plants to Outplanting Site – A wide variety of nursery stocktypes are 

available (Figure 10.80). Site factors should be considered before placing an order. The depth 

and width of containers are very important for seedling survival and growth. Sites with low 

precipitation during spring, summer, and fall should be planted with larger container sizes. 

Where soil moisture-holding capacities are low or vegetative competition for soil moisture 

is high, long containers should be considered. Where rock content is high and it is hard to 

excavate a planting hole, shorter container stocktypes should be used. Additional postplanting care must be implemented to compensate for shorter roots (See Section 10.3.4). The 

planting method dictates the size of the root plug. For instance, the expandable stinger and 

power augers require plug diameters no greater less than 4 inches. Large seedling stems and 

tops are required where animal damage is expected. 

Stocktype selection often determines seedling survival rates and how fast they grow in the fi rst 

years after planting. Typically the larger the root system, the better the survival and growth. 

Larger stocktypes cost more, so it is important to target the stocktype to the needs of the 

site and revegetation objectives. For instance, if quick establishment of vegetation for visual 

screening is an important objective, then a large stocktype would be ordered. On the other 

hand, if a revegetation unit is relatively unseen and the site has few limitations to plant survival, 

a small, less expensive stocktype would be ordered. While larger stocktypes are generally 

more expensive than smaller stocktypes, the total costs of establishing seedlings should be 

considered before settling on a smaller plant. Costs for replanting a site where smaller seedlings 

died in the fi rst year can be far more expensive than planting larger plants in the fi rst place.

Years in the Nursery – Bareroot stocktypes are often defi ned by the years they are grown at 

the nursery, whereas container plants are typically described by the size of the container. This 

is important when ordering plants because many species take longer than one year to grow 

to the desired plant size. If plants are needed for a project within one year, the revegetation 

specialist will need to order smaller size containers to assure that the roots can fi ll the plug.

Unbalanced or Holdover Stock – A common mistake is growing container plants with tops 

larger than the root system can support. This is often the result of poor planning, delay of 

projects, or poor selection of stocktype. For example, road projects are frequently delayed for 

a year, leaving the revegetation specialist with the problem of what to do about the seedlings 

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Figure 10.81 – The shoots of these pine seedlings 

have grown too large for the size of the root system 

which increases moisture stress after planting. In 

addition, the buds have broken dormancy, which 

means the plants will not tolerate rough handling 

(A). Poorly balanced or conditioned nursery stock 

will struggle to survive and grow after planting and 

exhibit signs of “transplant shock” (B).

A

B

293
that are being grown. Typically under these circumstances the nursery manager is asked to 

hold the seedlings in the same containers an extra year. While most will comply, they will do 

it reluctantly. The result is plants that are “top heavy” – the shoots are too large for the root 

system to support (Figure 10.81A). The results are often deceiving. The plants have not shown 

stress because they have been pampered under greenhouse conditions and care. Yet, once 

seedlings are outplanted on a typical harsh site, it will be a struggle to grow enough roots to 

keep the tops healthy and alive. Plants respond to the lack of moisture in what is referred to 

as “transplant shock” (Figure 10.81B) by shutting down growth and often turning yellow or 

“chlorotic.” Roadsides are stressful sites that require the very best quality plant material. A good 

example of the diff erence between well-balanced and poorly-balanced nursery stock is shown 

in Figure 10.82. 

Delays are common in roadside projects, so two viable options can be considered: 1) transplant 

the stock into larger containers, 2) reject the plants and place a new order. Option one 

is appropriate if the plants are being grown in small containers and a larger container is 

available for transplanting. If you are growing plants in a large container, it makes little sense 

to transplant into a still larger one. This option is often more costly than option two, which is 

simply starting over with the order. But starting over assumes available seeds and other starter 

plant materials, and enough time to reorder. And what can be done with the plants that are not 

being used? You or the nursery manager can contact land managing agencies and landowners 

in the general geographic area to see if they are interested in these plants. If they are not, there 

are often watershed councils or environmental groups that would appreciate the donation for 

their projects.

10.2.6.6 Obtain Seeds or Other Starter Plant Materials

Nursery-grown plants begin from source-identifi ed seeds or other “starter” plant materials 

(cuttings, smaller seedlings for transplants) that must be supplied at the beginning of the 

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Figure 10.82 – The ponderosa pine seedling in the photograph (A) was grown for four or fi ve 

years at a nursery and outplanted on a semi-arid site. The photograph was taken one year after 

outplanting and shows the seedling has undergone transplant shock due to the imbalance, or 

high shoot to root ratio, of the seedling when it was planted. The seedling was root-bound when 

it was planted. The tree responded by dropping most of its nursery needles and grew very little in 

height in the fi rst year. Photograph B shows a ponderosa pine seedling that was grown in a onegallon container for one year, then outplanted. Because this seedling had good balance and was 

not root-bound, it did not undergo transplant shock after it was outplanted. After two years, this 

seedling is well established. The brackets in both A and B show the current year leader growth.

A B

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contract (Figure 10.83). Since starter plant materials can take a year or more to obtain, it is 

important that these needs are identifi ed early in planning, and collection contracts are put 

into place as soon as possible. Locally adapted seeds of some trees can take years to obtain 

because some species do not produce a crop every year. The benefi ts and drawbacks of each 

type of starter plant material are discussed below.

Seeds – Starting plants from seeds is usually the least expensive method of plant propagation 

and off ers the greatest genetic diversity. The downside is that, for most species, seed 

propagation is slower than growing from cuttings or transplants. Crop production times will 

vary with species and nursery practices. Most woody plants take two to three years to grow into 

large plants from seeds and must be transplanted at least once. Other faster-growing species 

can reach shippable size in one growing season with good culture. 

Seeds are either collected in the wild by seed collectors, or fi eld-grown in an agricultural setting 

from tree and shrub seed orchards or from grass and forb seedbeds (See Section 10.2.4). Both 

wild-collected and fi eld-grown seeds are sometimes available from federal seed extractories, 

federal nurseries, Forest Service district offi ces, or BLM resource areas. These agencies usually 

have tree seeds for most seed zones that cover federal lands, and often some selection of shrub, 

grass, and forb seeds are available. It is worth checking to see if these sources are available 

before you decide to collect seeds from the wild. Seed dealers do carry inventories, so be sure 

to inquire as to species and collection source. The single best resource for seeds or nursery 

stock is the Plant Materials Directory, which is published yearly as a special issue of the Native 

Plants Journal:

Indiana University Press

Journals Department

601 N Morton Street

Bloomington, IN 47404-3797

TEL: 800.842.6796

Website: http://www.nativeplantnetwork.org 

Seeds obtained through federal facilities or seed dealers must report: 1) seed source – location of 

collection or seed zone; 2) year of collection; 3) seeds per pound; 4) % purity; 5) % germination, 

or tetrazolium (TZ) tests, from recent testing facilities; and 6) amount of noxious weed or 

other non-crop seeds. If seeds are not available through either of these sources, wild seed 

collection will be necessary. This can be done under the direction of district or forest botanist 

or by contract.

Once a plant production contract is awarded, nurseries will request information on each of 

the seedlots they will be sowing, including the latest purity and germination test results to 

determine the amount of pure live seeds. In addition, they will require the number of seeds 

per pound to calculate how many pounds of seeds from each seedlot will be needed to meet 

your order. They will also factor in the diffi culty of growing each species, called the nursery 

factor, which will be diff erent for each species, stocktype, and nursery. The nursery factor is 

a prediction of what percentage of 

seeds sown will become “shippable” 

seedlings, and considers losses 

during the growing season as well as 

those plants which are “culled” during 

harvesting. Nursery factors typically 

range from 30% to 50%, which means 

that they will need to sow 2 to 3 viable 

seeds for each plant they produce. 

You can get a rough idea of how many 

seeds should be acquired by using the 

seed tests and a nursery factor of 30%. 

If the nursery requests signifi cantly 

more seeds, then it is appropriate to 

inquire why more seeds are needed.

Starter Plants – Most large container 

stocktypes are started by moving 

smaller plants into larger containers 

Figure 10.83 – Nursery grown plants are 

propagated from source-identifi ed seeds or other 

starter plant materials. Usually, seeds or starter 

materials must be secured prior to the award of a 

plant production contract. 

Wild Seeds

Type of Propagule

Field-Grown Seeds

Wild Plants

Nursery-Grown Plants

Wild Cuttings

Nursery-Grown Cuttings

Nursery-Grown

Plants

295
or into bareroot growing beds. This 

practice is called transplanting, and 

it produces quality plants with large, 

fi brous, healthy root systems and 

large stems. Starter plants are typically 

grown from seeds or cuttings into 

small plants and then transplanted. 

In some cases, wildlings can be 

salvaged from the construction site 

and brought back to the nursery for 

transplanting. When ordering large 

containers, it should be specifi ed 

that there will be at least one, and 

sometimes two, transplanting 

operations. Growing starter plants 

large enough for transplanting 

usually takes a year. They are then 

transplanted, usually in the spring or 

fall, and grown for another year or 

two. If seedlings or rooted cuttings 

are available from other sources, these 

can be sent directly to the nursery for 

transplanting, which would decrease 

production time by a year.

Rooted Cuttings – Rooted cuttings 

(Figure 10.84) can be shipped directly 

from the nursery for outplanting or 

serve as starter plant material for 

transplanting into larger containers. 

One big advantage of this stocktype 

is that cuttings can be collected each 

year, whereas seeds may be more 

diffi cult to procure. While cuttings of 

most species are derived from stems or branches, some species like, quaking aspen (Populus 

tremuloides) must be started from roots. Rooted cutting production is discussed in detail in 

Section 10.2.5.

10.2.6.7 Develop Growing Contract

All nurseries experience weather extremes, insect or disease losses, equipment failures, and 

other production problems that can severely decrease the quantity and quality of the stock. 

Therefore, it is a good strategy to reduce these inherent risks by growing plants at more than 

one nursery. In doing this, you will begin to see the strengths and weaknesses of each nursery. 

Future ordering can use this information to decide where to grow each species.

Nursery Selection – The western United States has an abundance of nurseries that grow native 

plants, but few will off er plants from source identifi ed plant materials specifi c to your project. 

Obtaining genetically appropriate plants will require fi nding nurseries willing to grow seedlings 

from specifi ed genetic material. A current list of native plant nurseries can be found in the Plant 

Materials Directory (See Section 10.2.6.6). 

When considering a nursery for plant production, there are some basic factors to consider:

 · Proximity. Is the nursery close enough to visit occasionally?

 · Service. Is the staff easy to contact? Do they promptly return phone calls or e-mails? Are 

they friendly and helpful?

 · Expertise. Are they knowledgeable in restoration and revegetation?

 · Years in business. Has the nursery been in business for at least 3 years?

 · Seedling quality. Is the overall seedling quality high?

 · Seedling quantities. Are the orders regularly met or do they consistently run short?

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Figure 10.84 – Rooted cuttings are the quickest 

and easiest way to produce some woody plants, 

such as cottonwoods and willows.

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 · Price. Are prices competitive?

 · Willingness. Will the nursery try new things?

If there are doubts about one or more of these factors, you might consider growing at another 

nursery. Ultimately, the selection comes down to personal experience with nurseries and wordof-mouth from other revegetation specialists.

Seedling Orders – A plant production contract must detail the information you have developed 

in previous sections of this chapter:

 · Species,

 · Genetic source,

 · Starter plant material,

 · Stocktype,

 · Net amount of plants,

 · Month and year for plant delivery,

 · Minimum seedling specifi cations, and

 · How they will be processed and stored.

A few phone calls to nurseries will give you some idea which ones will grow the species, 

stocktype, and quantities necessary for your project. Nurseries can still be utilized if they can 

only meet a portion of the order. Other nurseries can produce the remainder because there 

is less risk by sending plant orders to several nurseries. Contracts can be developed once you 

have some idea of what portions of an order a nursery can produce.

Plant Processing and Storage – Once seedlings have reached the target size and age at the 

nursery, they are harvested, stored, and processed for shipping. If the plants are bareroot 

seedlings, they are lifted from the soil, graded, and packaged. Container seedlings can be 

extracted from the containers, graded, and packaged, or sent to the planting site in containers 

and extracted immediately before planting. Either way, most stocktypes will be held at the 

nursery for one to six months, depending on when they are needed for planting. “Planting 

windows” are discussed in more detail in Section 10.3.4.

Storage times are longest for seedlings planted in the late winter and spring. For these orders, 

plants are extracted from their containers or lifted from the soil in the winter when they are 

least susceptible to the stress or damage associated with extraction, handling, and packaging. 

Plants in this condition are dormant. The onset of plant dormancy for deciduous plants is often 

around the time when plants have lost their leaves in late fall; the end of dormancy begins just 

before the buds begin to swell in the late winter to spring. The dormancy period for conifer 

species is not visibly discernible, but typically follows a similar time frame as deciduous species. 

Seedling dormancy in the western United States typically extends from December through 

February, but the dates will vary by nursery. If plants are to be extracted and held in cold 

storage for long periods, it is important to known when the nursery is extracting and handling 

the seedlings to be sure these operations are done when seedlings are dormant. Seedlings that 

are extracted or lifted outside the seedling dormancy period and stored for any length of time 

will survive and perform poorly.

When plants are lifted from bareroot beds or extracted from containers, they are also being 

graded for size and appearance. Unless otherwise agreed, the size specifi cations stated in the 

contract will be the grading criteria (Figure 10.85). It is good to be at the nursery during lifting/

extraction and grading to see which seedlings are being thrown away and which seedlings 

are considered shippable. Bareroot and smaller container plants are graded and boxed for 

refrigerated or freezer storage. Storage containers will have important information about the 

plants, such as seedlot, date packed, client name, and the number of seedlings in the container. 

Plants are typically held in cooler storage (32 to 35 °F) from a few weeks to two months. If 

longer storage is required, freezer storage (28 to 31 °F) is recommended to maintain seedling 

quality and reduce the chance for storage molds. 

Large container stocktypes (typically those equivalent to a half gallon or larger) are stored and 

transported in the containers in which they are grown. They are typically stored in shadehouses 

or other sheltered storage. In cold climates, the roots should be insulated to protect against 

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Inset 10.18 – Assessing Poor Quality Nursery Stock

Poor quality planting stock can be caused by biotic (e.g., diseases, insects) or abiotic 

factors (e.g., imbalance of soil moisture, temperature, nutrients, and pesticides) in the 

nursery resulting in det rimental, and sometimes devastating, eff ects on seedling survival 

and growth when outplanted. Infection with various pathogens, or biotic causes, may not 

necessarily be manifested in a nursery, but may cause stunting or mortality once seedlings 

are under stress following outplanting. Revegetation specialists should be aware of the possible nursery diseases in order to either recognize or discuss with nursery personnel during 

visits to inspect their seedlings.

Diseases caused by fungi, water molds, bacteria, and viruses can often be diffi cult to 

distinguish from damage caused by abiotic events or factors. If damage or chlorosis of 

seedlings is noted, it is recommended to check with the nurs ery manager to determine the 

history of the seed lings, what pathogens are traditionally a problem at the nursery, and 

what, if any, have occurred during the current growing season. Hamm and others (1990) and 

Landis and others (1990) provide more detailed information on nursery pests.

Shoot and foliage diseases can be caused by a variety of organisms, with various levels of 

impact on seed lings. Fusarium hypocotyl rot (caused by Fusarium oxysporum) can cause 

large losses in the nursery from July through October. Gray mold (caused by Botrytis 

cinerea) can cause signifi cant damage to densely grown bareroot and container seedlings, 

as well as nursery stock stored in less than optimal conditions (Hamm and others 1990). 

The mycelium and gray spore clusters are often easily visible to the naked eye. Botrytis can 

girdle infected seedlings, increasing mortality rates following outplanting. Minor shoot and 

foliage diseases, such as shoot blight (caused a number of organisms including Sirococcus 

spp., Phomopsis spp., and Phoma spp).and needle-casts and other foliage diseases tend to 

deform or stunt seedlings, but do not result in sig nifi cant mortality in the nursery or in an 

outplant ing situation.

Root diseases may be the most in sidious of nursery seedling diseases. Since seed lings are 

cultured under optimum conditions for growth, symptoms are often masked throughout the 

growing season, manifested only during out planting stress or drought stress in succeeding 

years. Most conifers, and many native species, are susceptible to root diseases and root rots 

caused by Phytophthora spp., Fusarium spp., and Cylindro carpon spp. These diseases will be 

manifested in the nursery in pockets of symptomatic seedlings or mortality, particularly 

in areas of poor drainage or previous infestation. Outplanting seedlings infected with 

these patho gens will result in reduced survival. In addition, trans fer of these organisms to 

outplanting sites may result in infection of the planting area. This specifi cally is a problem 

with the root disease, Phytophthora lateralis. The spread of this disease from infected 

seedlings can devastate populations of established Port Orford cedar.

Not all seedling quality problems are caused by biotic factors – many are one-time damaging 

events that occur during a short time span with a regular distribution through out the fi eld 

or greenhouse (Mallams 2006). If fo liage discoloration, foliage or stem wilting or die-back, 

seedling stunting, or mortality occur in large patches or over large areas in the nursery, the 

causes are often abi otic. Outplanting seedlings that have been stunted or damaged in the 

nursery can reduce seedling growth and survival, as well as increase the time required for 

site recovery. However, the symptoms of abiotic damage are often more apparent, and the 

consequences more easily predictable, than damage caused by pathogens.

Although restoration personnel have little to do with nursery cultural practices and dis ease 

mitigation in the nursery, several options exist to prevent or control disease problems on 

restora tion sites. Disease mitigating measures are similar to insect mitigating measures: 

1) only plant healthy stock because weakened or stressed seed lings are more susceptible 

to diseases both in the nursery and on the outplanting site, 2) plant a variety of species to 

avoid outplanting failure due to infestation of any single disease, 3) create a healthy soil 

environment – seedlings grown on poor sites or on sites outside of the species environmental 

ranges will be placed under stress and more susceptible to disease infection. 

298
cold injury. During unseasonably warm periods during the late winter or early spring, large 

container stock should be monitored for drying and irrigated if necessary. 

Grading Specifi cations – There are no nursery-wide minimum nursery standards for the size 

and appearance of nursery grown plants because of the wide variety of ages, stocktypes, and 

growth patterns of native species. Nevertheless, you must establish some criteria for accepting 

or rejecting plants or you might be receiving marginal plants. Being present at the time of 

packing is the most eff ective way to negotiate grading standards with the nursery and assure 

that you receive quality plants. 

Typical grading standards fall into the following categories (Figure 10.85): 

Stem diameter at root collar (“caliper”) – Stem caliper is the single most important morphological 

measure of nursery plant quality and has been consistently correlated with outplanting survival 

and growth. Diameter is not necessarily a good measurement for rooted cuttings since the size 

of the stem is dependent on the original diameter of the cutting. A typical grading specifi cation 

for many bareroot and container stocktypes is a minimum diameter of 3.5 to 4.0 mm for oneyear-old seedlings, and greater than 4.0 mm for plants grown for two years. Discuss these 

specifi cations with the nursery, since not all species will grow to these sizes in this time frame.

Shoot height – The height of the plant is measured from the root collar, or original ground 

line, to the top of the terminal bud. Some species do not form a terminal bud, so the swollen 

meristem tip or even the average top of the crown is used.

Root system – The root system of the plant should be examined carefully. For bareroot stock, 

the roots should be well developed and fi brous and approximately the same area as the 

crown. For container stock, the root “plug” must be fi rm but not too root-bound. If the roots 

have spiraled and formed a tight mass at the bottom of the plugs, they should be trimmed 

during harvesting. 

Seedling Balance – Nursery stock should have a good ratio between the amount of foliage and 

the root system. This is traditionally expressed as a shoot-to-root ratio (S:R), and typically ranges 

from one or two part shoots to one part roots (an S:R from 1:1 to 2:1). This grading standard is 

a qualitative determination to whether the root system is large enough to support the aboveground portion of the plant. 

General plant health – During grading, nursery stock should be inspected for physical injury or 

disease. Root disease is a particular hazard of container stock, and soft or moldy roots should 

be suspect. Scraping the roots with the blade of a knife should reveal white healthy tissue. 

10.2.6.8 Administer Contract

The nursery manager should be required to maintain records on how the plants were cultured. 

The basic information should include: date plants were started; the type, rates, and timing 

of fertilizer applications; irrigation schedules; greenhouse settings (temperature, lighting, 

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Figure 10.85 – Grading criteria for 

seedlings are based primarily on stem 

diameter, height, terminal bud, root 

volume, and integrity.

Shoot height

Stem diameter

at root collar

(caliper)

Terminal bud

or swollen 

meristem

Root plug volume

and integrity

299
humidity); pesticide applications; and any signifi cant problems that might have occurred with 

the seedlot. The nursery is also required to give an accounting, or inventory, of your plant 

orders by late summer. 

It is important to visit nurseries at least once a year, but more often is better. These visits will 

give you an indication of the quality of the stock you will be receiving and whether the number 

of seedlings you ordered is being met. It also helps strengthen the relationship between you 

and the nursery manager, which often leads to more attention being given to your orders. 

One of the best times to visit is during the initial plant establishment phase, which is during 

the late spring or early summer after seeds have germinated or seedlings and cuttings have 

been planted. If there are stock problems, they are most likely to be observed at this time. If 

for some reason there is a fall-down in the inventory or the seedlings look unhealthy at this 

time, you have an opportunity to discuss it with the nursery manager. If caught early enough, 

there can be time to start more plants. At the minimum, identifying problems early will give 

you time to adjust your planting plans as well as adjust other contracts that depend on the 

plant inventory.

Another good time to visit is during the processing of plants for storage or shipment. Your 

presence at this time helps the nursery manager with questions that might arise about grading 

specifi cations, packaging materials, pruning, and other operations that occur at this time. It 

gives you a good picture of what type of stock you will be receiving when it is shipped to 

the planting areas. It is never an enjoyable experience to open up a box of seedlings, with 

planters standing around, and be surprised to fi nd that the seedlings are not at all what you 

were expecting.

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10.3 INSTALLING PLANT MATERIALS

Once the project site has been prepared (See Section 10.1, Soil and Site Treatments) and 

the plant materials have been obtained (See Section 10.2, Obtaining Plant Materials), the 

vegetation can be installed on the project site. The following implementation guides cover 

the methods for installing seeds, cuttings, and plants. Section 10.3.1, Seeding, discusses the 

diff erent methods of seeding, how to formulate seed mixes, determining seeding rates, and 

assuring quality. A specialized form of seeding, hydroseeding, is discussed in Section 10.3.2. 

Section 10.3.3, Installing Cuttings, outlines cutting installation techniques most commonly 

used in biotechnical engineering designs. Section 10.3.4, Installing Plants, discusses techniques 

for planting bareroot and container plants. It also discusses seedlings, plant handling, storage, 

and quality control measures.

10.3.1 SEEDING

10.3.1.1 Introduction

Seeding is the distribution of seeds for the purpose of establishing seedlings at a desired 

density and species composition. Optimal seeding operations must take into consideration: 

1) how seeds are uniformly distributed over an area, 2) where seeds are placed vertically (that 

is, in, on, or under the soil surface), 3) species composition in the seed mix, and 4) when seeding 

takes place. These factors must be adapted to each revegetation unit to account for the unique 

climate, soils, and species requirements of each site.

Seeding is often coupled with other operations, such as fertilization, soil amendment 

applications, and soil stabilization treatments. While accomplishing these objectives at the same 

time as seeding often makes practical sense from an economic and scheduling standpoint, it 

might not always be best for the short-term establishment of native vegetation. It is important 

to consider the eff ects of combining too many operations into the actual sowing operation. It 

may be necessary to plan some of these operations at diff erent times. For example, fertilizing, 

which is often done during the seeding operation, might best meet objectives if applied 

separately from seeding (See Section 10.1.1).

This section will cover the diff erent steps in developing a seeding plan: 1) identifying seeding 

areas, 2) determining seed application methods, 3) developing seed mixes, 4) determining 

sowing rates, 5) preparing seed mixes, 6) selecting sowing dates, and 7) applying seed and 

assuring quality. 

10.3.1.2 Identify Seeding Areas

It is important to visit the project site as soon after road construction as possible and specifi cally 

identify seeding areas on the ground. If road construction is a multi-year project, fi nished slopes 

should be assessed for seeding while the remaining construction continues. While most of the 

seeding areas will conform to the revegetation units developed during planning, sites always 

look diff erent after construction. A fi eld review should note where topsoil has been placed, 

presence of surface rock, surface roughness, accessibility by equipment, microclimate, soil 

compaction and other site factors. These factors will be used to develop: 1) seeding methods, 

2) sowing dates, 3) seed mixes, and 4) seeding rates for each of the seeding areas. 

Seeding areas are located on a map and by road station. For each seeding area, acreage can 

be calculated using methods described in Figure 9.2 in Chapter 9, Implementation. These 

calculations must consider the areas where seeding will actually take place. For instance, 

seeds should not be applied in areas where herbicides will be used for maintenance. At 

the end of the fi eld survey, total acreage for each seeding area will be summarized and this 

information will be used in developing seed mixes for each seeding area (See Section 10.3.1.6 

and Section 10.3.1.7). 

10.3.1.3 Determine Seeding Methods

There are a variety of methods for applying seeds available to the revegetation specialist. 

The challenge is matching these methods to the sites encountered in mountainous terrain. 

Typically, the site characteristics of each seeding area will dictate the type of seeding method 

used. For example, a road project has three revegetation units – a steep, north-facing slope; an 

obliterated road; and a rocky south slope. Hydroseeding could be planned for the steep, northRoadside

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facing slope where other equipment cannot reach. On the obliterated road, several ground 

based seeding methods could be used, including mixing seeds into the soil, or broadcasting 

on the surface and covering with a mulch. The south-facing slopes could be hand-seeded or 

hydroseeded, then covered by a mulch to keep the seeds from drying out during germination. 

Each project needs to approach seeding with a strategy that is the most effi cient and will 

provide optimal conditions for seed germination.

Each species has a unique seed covering requirement. While seeds of most species must be 

buried in the soil or covered by mulch to germinate, some species actually require some exposure 

to light to germinate and must not be covered very deeply. A general rule for seed covering is 

to bury seeds at depths from twice (Munshower 1994) to three times (Monsen and Stevens 

2004) the seed diameter. The deeper the seeds are covered, the less likely they will dry out 

during germination. The tradeoff , however, is that seedlings will have to expend more energy 

to emerge from deeply buried seeds. This can ultimately aff ect early seedling establishment.

The ideal seedbed, as defi ned by Monsen and Stevens (2004), is “one in which the seed is 

fi rmly enclosed within soil particles to provide hydraulic conductivity of moisture to the seed. 

Seeds should be placed deep enough to prevent rapid drying but shallow enough to allow 

natural emergence.” Creating an ideal seed environment is an important practice, especially in 

nurseries, farms, or gardens where the objective is to create a uniform plant crop. All operations 

in these settings must be standardized and uniform (e.g., correct seed depth, optimum lighting, 

uniform irrigation, uniform seed densities, etc.). While uniformity and standardization can be 

applied to wildland revegetation, an alternative strategy might be considered. This strategy 

starts from the premise that we really cannot know much about the specifi c germination and 

early seedling growth requirements of diff erent native species at each seeding site. For this 

reason, we should be creating a variety of environments, or “regeneration niches” (Grubb 

1977), where seeds might fi nd the right conditions for germination (Figure 10.86). Further, we 

should apply a range of native species to fi ll these environments. With wildland revegetation, 

uniformity is not the objective. In fact, non-uniformity will most likely fi t with the surrounding 

plant communities.

Vertical seed placement, where seeds are vertically distributed in soil or mulch layers, can be 

grouped into the following categories:

 · Broadcast onto the surface,

 · Pressed into the soil surface,

 · Mixed under the soil surface,

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Figure 10.86 – When a seed mix, ranging from small to large seeds, is applied to an uneven 

surface (A) and covered by a long-fi bered mulch (B), a range of germination environments are 

created. Optimum germination environments for large seeds occur in depressions where deeper 

seed cover occurs; optimum germination environments for small seeds, needing less cover, occur 

on the ridges where mulch is not as thick.

large

small

medium

B mulch

A B

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 · Drilled under the soil surface,

 · Covered with long-fi ber mulch,

 · Mixed into long-fiber mulch, and

 · Mixed into hydromulch.

Vertical seed placement methods will be discussed in the following sections in the context of 

how they aff ect germination and seedling establishment. 

Seeds Sown on the Soil Surface – One of the most common forms of seeding is broadcast 

seeding, which is casting seeds on the surface of the soil with a rotary spreader or by hand. 

Broadcast seeding is almost always the least expensive form of seeding. Rotary spreaders can 

be attached to most types of vehicles, including all-terrain vehicles and pickups, and used 

where vehicle accessibility is good. Where slope gradient or accessibility limits mechanical 

seeding, using a hand-held broadcast seeder is an option. While manual broadcast seeding 

might be considered a very low-tech method, it still has an important place in revegetation. 

Manual broadcast seeding off ers the opportunity to spot-seed microsites at diff erent seed 

rates and seed mixes. For example, two people could hand seed a steep cut slope requiring 

two diff erent seed mixes – the lower portion of the slope sown with a grass and forb seed mix 

and the upper portion with a shrub and seed mix. In another instance, a fi ll slope composed 

of rocky outcrops interspersed among deep soils has two distinct microsites that could be 

seeded separately with diff erent seed mixes. With knowledge of the road objectives, several 

hand seeders can apply seeds across a project area that mimics the vegetative patterns of the 

landscape. Spot-seeding can also be a method of applying valuable seeds or “unique” species 

to strategic locations. For instance, showy forbs that are expensive to obtain or require a specifi c 

habitat can be spot-seeded in those locations. 

The disadvantage of broadcast seeding is that seeds are not covered by soil or mulch (Figure 

10.87). Since seeds need intimate contact with the soil to germinate, broadcast seeding typically 

leads to low establishment of seedlings. If greater quantities of seeds are sown; however, some 

seeds will fi nd microsites with high humidity (between surface gravels or rock) or will be 

covered by soil particles that have been moved through erosion processes. Estimates of 50% to 

75% more seeds must be sown to compensate for the inability of seeds to germinate or the loss 

of seeds to rodents (Monsen and Stevens 2004). Survival factors must be adjusted downward 

when calculating sowing rates for seed mixes (See Section 10.3.1.6). Broadcast seeding on 

roughened surfaces can potentially increase germination rates, especially if seeds are sown 

in the fall. The probability that seeds will be covered by sloughing soil over time is increased 

(Stevens and Monsen 2004), so it is important that the soil surface be left as rough as possible 

where broadcast seeding will be used. 

Seeds Pressed into the Soil Surface – Seed that is sown on the surface and pressed into the 

soil increases germination rates over broadcast sowing. Seeds are in fi rm, intimate contact 

with the soil, which increases available water to the seeds (Stevens and Van Epps 1984) (Figure 

10.88). Imprinting produces a variety of microsites which may benefi t the germination of a mix 

of species (Stevens and Monsen 2004). This type of seeding is accomplished with imprinting 

equipment (See Section 10.1.2.4). In this operation, seeds are dropped from a seeder mounted in 

front of the imprinter and then pressed into the soil. Imprinting works well for small to medium 

sized seeds; seeds are in fi rm contact with the soil but not buried too deeply to aff ect seedling 

emergence. In some cases, imprinting small- and medium-sized seeds can result in germination 

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Figure 10.87– Broadcast seeding leaves 

seeds exposed on the soil surface where 

they are not in contact with the soil. 

Figure 10.88 – Pressing seeds into the soil 

surface improves germination by increasing 

soil contact. 

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as good as, or better, than drilling seed 

(Haferkamp and others 1985). Larger 

seeds must be covered by soil or mulch for 

adequate germination. Imprinting seeds 

cannot occur on steep slope gradients or 

slopes with high rock content. Sites that are 

too steep for tractor access are too steep 

for current imprinting equipment. 

Seeds Mixed Under the Soil Surface –

Mixing seeds into the surface of the soil is 

one of the best ways to achieve optimum 

germination (Figure 10.89). Mixing is done 

in two stages – seeds are applied on the 

soil surface by either broadcast seeders or by using a seedbox and drop tubes; seeds are then 

incorporated into the soil by dragging anchor chains, disk chains, cables, pipe harrows, or 

other implements behind a tractor. Equipment has been developed for wildland conditions 

that will seed and incorporate in one operation. The “ripper-seeder-harrow” (Figure 10.90) is 

a specialized seeder that subsoils, broadcasts seeds, and mixes in one operation. Use of this 

equipment is limited to slope gradients of 3H:1V or less and non-rocky soil surfaces. 

When mixing seeds into the soil on steeper slopes, any method that scarifi es the soil surface 

after seeds have been broadcast will mix the seeds into the surface. Using a hand rake to 

incorporate broadcast seeds into the surface works well, and can be used in areas where 

expensive or valuable seeds have been applied. This type of seed placement requires that the 

seed depth be monitored to assure that it is not buried too deeply. Seeds should not be mixed 

deeper than one inch. 

These application methods allow seeds to be mixed evenly through the soil and not concentrated 

in rows, as they are with drilling (see below). However, soil is left loose around the seeds, which 

decreases water-holding capacity. If seeds are sown in the fall and do not germinate until the 

following spring, natural packing of soil around the seeds will occur. 

Seeds Drilled Under the Soil Surface – Using a seed drill is another method for covering seeds 

with soil. Seeds are not actually drilled into the soil, as the name implies, but sown just under 

the surface in rows. Seed drills 1) open the surface of the soil with a disk or tine; 2) drop seeds 

from a seedbox, through tubes, into the open furrows; 3) close the furrows with a disk; and 4) 

pack the soil fi rmly around seeds with a press wheel. Cropland drills have been developed for 

the agricultural industry. However, this equipment has limited applicability on highly disturbed 

sites because rocky soils and uneven soil surfaces create diffi culties in placing seeds at proper 

soil depths. Several drills have been developed for rangeland restoration that compensate for 

these limitations. The Rangeland and Truax® drills were specifi cally developed for seeding rocky, 

uneven surfaces. The Truax® drill was an improvement on the Rangeland drill, and includes 

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Figure 10.90 – The “ripper-seeder-harrow” equipment was developed by the Umatilla National 

Forest. This equipment prepares the soil surface and mixes the seeds into the surface in one 

operation. Soils are loosened 

using subsoil tines, leaving 

a roughened soil surface (A). 

Seeds are metered from a 

seedbox through drop tubes 

onto the soil (B), where seeds 

are mixed into the soil using 

a chain harrow (C). Blueprints 

for this equipment can be 

obtained from the USDA 

Forest Service, Missoula 

Technology Development 

Center (MTDC).

Figure 10.89 – Seeds mixed under the soil 

surface puts them in direct contact with the 

soil, greatly improving germination.

304
three seed boxes that can independently distribute seeds at diff erent depths corresponding to 

the size and shape of the seeds (Stevens and Monsen 2004). 

Seed drills concentrate seed into rows (Figure 10.92), creating a greater potential for competition 

between emerging seeds within rows than if seeds were broadcast. For example, a seed mix 

with an aggressive species will emerge and dominate the row of seeds at the expensive of less 

aggressive species. The three seedboxes on the Truax® seed drill can be used to compensate 

for this potential problem. The less aggressive species are placed in separate seedboxes and 

sown in separate rows. If more than one seedbox is used, separate sowing rates must be 

calculated for each box. Typically, lower seed rates are used in drilling operations because the 

seeds are concentrated in rows and closer together. Where rodents are present, drilled seeds 

are more prone to being excavated by rodents that simply follow a row of seeds (Stevens and 

Monsen 2004). 

Seeds Covered With Long-Fibered Mulch – Optimum seed germination is obtained under 

long-fi bered mulch. The mulch provides a moisture barrier that protects seeds and keeps soil 

from drying (Figure 10.93). Soil moisture is maintained longer around seeds than if they were 

strictly covered by soil. This is a two-stage operation in which seeds are broadcast on the soil 

surface and then covered by mulch. The thickness at which the mulch is applied depends on 

the seed size and the type of mulch. Small seeds will require less cover than large seeds. The 

rate at which mulch can be applied varies by the characteristics of each type of mulch. Wood 

strands and straw, for instance, can be applied at higher rates (thicker layers) than composts or 

chips because more light is able to penetrate these mulches, allowing seed germination and 

seedling establishment. See Section 10.1.3 for further discussion of mulches.

Sowing seed mixes that contain a variety of seed sizes will require that the mulch not be 

uniformly applied. One strategy is to begin with a roughened seedbed as shown in Figure 

10.86. Because the surface is not even, mulch will settle in depressions and be thicker than 

on the ridges. Monitoring the application rates is important to assure that seeds are covered 

with the proper mulch thickness. While covering seeds with long-fi bered mulch is the most 

favorable method for optimum seed germination, it is also the most expensive.

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Figure 10.92 – Seed drills place seeds in 

rows under the surface where they are in 

direct contact with the soil.

Figure 10.93 – Covering broadcast seeds 

with long-fi bered mulch is very eff ective in 

conserving moisture around the seeds.

Figure 10.91 – Seed sowing and 

mixing equipment can be attached 

to most types of ground based 

equipment, including all-terrain 

vehicles. A seed spreader attached 

to the back of an all-terrain vehicle 

broadcasts seeds on the soil 

surface and a chain harrow mixes 

seeds into the soil.

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Seeds Mixed into Long-Fibered Mulch – Seeding and mulching are often combined into one 

operation (Figure 10.94). Most mulch blowers have seed metering systems which distribute 

seeds with the mulch as it is being applied to the soil surface. Seeds in this operation are 

distributed within the mulch, as opposed to being placed between the soil surface and mulch 

layer. Although one operation is more effi cient, seed germination and seedling emergence 

rates are typically lower than when seeds are broadcast on the surface and covered with mulch. 

Seeds are not in contact with the soil when mulch and seed are mixed. Unless the mulch has 

a high water-holding capacity, moisture around the seeds will be limiting during germination 

and seedling emergence. It is important to know how much moisture a mulch can hold when 

deciding whether seeds will be mixed with the mulch or broadcast applied fi rst then covered 

with mulch (See Section 5.2.2.1 for determining moisture holding capacities of mulches). 

Composts, for instance, have high water-holding capacities, and seeds will germinate well in 

this material; ground or shredded wood mulch and wood strands have very little water-holding 

capacity and seed germination will be poor. Seed rates should increase relative to how much 

moisture the mulch is expected to hold. For low water-holding capacity mulches, seeds in the 

upper portions of the mulch will not germinate or will germinate poorly. Seed rates in this type 

of mulch should be increased by 25% to 50%.

Seeds Applied in Hydromulch – When seeds are applied through a hydroseeder (See Section 

10.3.2), they will lay on the soil surface surrounded by a thin covering of fi ne-textured wood 

fi bers (Figure 10.95). At rates of 1,000 lb/ac hydromulch, seeds will be covered with less than 

0.25 inch of mulch, with some seeds not covered. As rates approach 3,000 lb/ac, mulch 

thickness increases to over 0.25 inch, with most seeds being covered. Hydromulch has a high 

water-holding capacity, maintaining up to two and a half times its dry weight in water. This 

can be benefi cial to seeds during germination. However, unless very high rates of hydromulch 

are applied, many seeds in the slurry are not covered by the hydromulch. Some hydroseeding 

operations try to compensate for this by applying a slurry containing seeds fi rst, and covering 

the seeds with hydromulch with a second pass. The thin seed cover is favorable for only small 

seeded species. Seeds can be damaged in the hydroseeding operations through the pumps 

and agitators, or by hitting the ground at very high speeds during application. 

Even with these limitations, hydroseeding is still one of the most common methods of applying 

seeds to road construction disturbances. It is often the only way to place seeds on steep, 

rough terrain encountered in mountainous regions. Compensation for these limitations has 

had varying degrees of success. Possible variations include: 1) increasing the amount of seeds, 

2) applying seeds in the fi rst pass, then covering with hydromulch in the second pass, and 3) 

applying higher rates of mulch. Fall hydroseeding also increases establishment rates. Overwintered seeds are ready to germinate on the fi rst warm days of late winter or early spring when 

humidity levels are high. In addition, hydraulic mulches are more likely to stay moist for longer 

periods of time. Hydroseeding is simpler than dry seeding because there is no seed metering 

system; seed mixes are simply mixed into the hydroseeder tank and applied. See Section 10.3.2 

for more discussion on hydroseeding.

10.3.1.4 Formulate Seed Mixes

The seed mix refers to the species composition being applied over a seeding area. It is important 

to avoid applying a single species to a site. Since highly disturbed sites typically are extremely 

variable in soil temperatures, fertility, soil moisture, solar radiation, and other site factors, it is 

Figure 10.94 – Seeds mixed into longfi bered mulch have less contact with soil, 

which can reduce germination.

Figure 10.95 – Applying seeds in a 

hydromulch places a portion of seeds on 

the soil surface and some suspended in the 

hydroseeding matrix above the surface. 

306
important to apply a number of species in a seed mix to assure that all possible microsites are 

populated (Monsen and Stevens 2004). Microsites that are unfavorable to one species might be 

favorable to others. Applying a mix of species also assures that if there is a problem with the 

germination of one species, the other species will fi ll in. The composition of seed mixes and 

sowing rates should be based on the growth habits of each species and the soils and climate 

of the site.

It is preferable to avoid mixing slow-growing species with fast growers, because the fast 

growers will out-compete the slow growers for space and resources (Monsen and Stevens 

2004). Separating slow growers from fast growers is not always possible. The seed quantities 

must therefore refl ect higher ratios of slow growers to fast growers to achieve some degree of 

success. Shrubs and trees are typically less aggressive than grasses during the establishment 

phase, and should be applied in a separate mix or planted as seedlings. Grasses tend to be 

more aggressive than forbs. However, if the Truax® seed drill is used, they could be applied in 

the same area but in diff erent rows using the separate seed boxes. Some species take several 

years to develop. A mixture of fast-growing annuals and slow-growing perennials will assure 

that there is cover the fi rst year, yielding to more robust perennials in the succeeding years.

Disturbed reference sites can be good indicators of species that are adapted to the climate and 

soils of the project area. Vegetative surveys conducted during the planning stages should show 

the proportions of species that can be expected, and these fi ndings should become the basis 

for developing species composition and ratios of each species. Prior to determining sowing 

rates, the proportion of each species within each seed mix should be set. This information will 

be used to determine seeding rates for each species.

10.3.1.5 Determine Sowing Rates

The sowing rate is the amount of seeds of each species in a seed mix that are applied in a 

given area. Sowing rates are calculated for each species that compose a seed mix. These 

calculations are performed twice – once during the development of seed increase contracts 

to obtain an approximate quantity of seeds to propagate for the entire project, and several 

months prior to actual seeding when seed inventories are known and exact seeding areas are 

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Figure 10.96 – Assembling a seed mix requires sowing calculations for each species in the mix. 

This fi gure shows one way to calculate the quantity of seeds for one species (e.g. Elymus glaucus

[ELGL]) in a mix. These calculations must be made for each of the remaining species in the mix.

A Number of seeds/lb: 128,000 seeds/lb From seed tests

B Purity: 92 % From seed tests

C Germination: 89 % From seed tests

D A * B / 100 * C / 100 = 104,806 PLS/lb Number of PLS per pound of bulk seed

E First year survival: 20 % The estimate of PLS of ELGL that 

become seedlings

F Target 1st year 

seedling density: 20 seedlings/ft2 Desired number of seedlings (per ft2) 

of all species in seed mix after 1 year

G Target composition: 35 % Target percent of total 1st year plants 

composed of ELGL

H (F / E) * G = 35 PLS/ft2 PLS of ELGL to sow per ft2

I 43,560 * H / D = 14.5 pounds/acre Pounds of ELGL to sow on a per acre basis

J Area to seed: 5.5 acres Total area for seed mix

K I * J = 80 lbs Total ELGL needed for seed mix

L Quantity of 

containers: 4 bags/acre For handling

M I / L = 3.6 pounds/bag Total weight ELGL to put into each 

seed mix bag 307
located. The calculations made prior to seeding will be used to assemble the seed mixes for 

each seeding area. 

Each species requires a set of data to calculate the total pounds of seeds needed in a seed mix 

which includes: 

 · Pure live seeds per pound of bulk seeds,

· Estimated first year survival,

· Target first year seedling density for all seeded species,

 · Percentage of density composed of each species, and

 · Area that will be seeded with seed mix.

Figure 10.96 shows one method for calculating the amount of seeds needed of each species in 

a seed mix. Since a seed mix is made up of several species, calculations must be performed on 

each species. In this example, blue wildrye (Elymus glaucus) is one of several species included in 

a seed mix. The end result of these calculations is the number of pounds of blue wild rye seeds 

that must be added to each seed mix bag. 

Pure Live Seeds Per Pound (PLS/lb) – When purity and germination are multiplied together and 

divided by 100, the resulting value is the % pure live seeds (PLS). It represents the percentage of 

the gross seed weight that is composed of viable seeds (See Figure 10.65 in Section 10.2.4). For 

example, if germination is 89% and purity is 92%, the PLS would be 82%. When PLS is multiplied 

by the number of seeds per pound, the result is the pure live seeds per pound of gross seeds 

(PLS/lb). This value is often used in seed and sowing calculations, and it states the approximate 

number of seeds that will germinate in a pound of gross seeds under ideal (test) environments. 

For example, the PLS in Figure 10.96 is 82%, and the number of seeds per pound is 128,000. The 

total PLS/lb is (82/100) * 128,000 = 104,806 (Line D in 10.96). Tests for purity, germination, and 

seeds per pound are run by State Certifi ed Seed Testing Laboratories and obtained from the 

seed producer or supplier. 

First Year Survival – Not all viable seeds develop into established seedlings after being sown 

on a disturbed site. The conditions encountered on revegetation sites are generally unfavorable 

for germination and plant establishment. The fi rst year survival factor refl ects the eff ect of the 

harshness of the site on plant establishment (Line E of Figure 10.96). It is a prediction of the 

percentage of PLS that germinate and become established plants after the fi rst growing season. 

A favorable site, for instance, will have a high survival factor because a high percentage of live 

seeds will germinate and establish into plants; a harsh site will have a low fi rst year survival 

factor because seeds will germinate poorly, resulting in plants less likely to survive over the dry 

summer months. Unfortunately, there are currently no established fi eld survival factors for the 

western United States. Therefore, the revegetation specialist will have to make estimates based 

on experience and an understanding of site factors, seed handling, and sowing methods. 

How much fall down actually occurs? Even under very controlled growing environments, such 

as those found in seedling nurseries, survival factors are much lower than most would think. It 

is not uncommon for bareroot seedling nurseries to set fi rst year survival values between 65% 

and 75% (USFS 1991). Compare the highly controlled environment of a nursery to seeding in 

the wild, where precipitation is intermittent and soils are depauperate. It should be no surprise 

to fi nd that only 10% to 20% of the live seeds sown in the wild actually turn into live plants the 

fi rst year after seeding (Monsen and Stevens 2004; Steinfeld 2005).

Estimating the fi rst year survival is always a guess. It is interesting that very exact data from seed 

tests are used for a portion of the sowing calculations, followed by a broad approximation of 

how well viable seeds will actually germinate and become established in the fi eld. Unfortunately, 

this information is hard to obtain. Monitoring data collected in the spring and fall, after the 

completion of each seeding project, can be used to develop a basic understanding of how 

seeds perform in the fi eld under various soils, climates, and mitigating treatments. First-year 

monitoring that measures seedling density is useful in this regard. The number of seedlings 

can be counted in a series of photoplots, and the average number of seedlings per square foot 

can be calculated. The average seedling density, divided by the average number of PLS sown 

per square foot (line H of Figure 10.96), gives the survival factor for that project area. Steinfeld 

(2005) performed this type of monitoring for several seeding projects six months after sowing 

on southwest Oregon sites and found the results to be very low (15% of viable seeds became 

established plants). If this type of assessment is conducted over a range of seeding projects, 

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308
survival factors could be developed for a range of soil and climate conditions. It would be good 

to understand how survival factors change with diff erent types of seed covering methods. 

Factors to consider when estimating survival factors are shown in Table 10.16. Chapter 5 

discussed how these factors aff ect plant growth. Sites with low fi rst year survival would have a 

large number of limiting factors. Very poor sites can have survival factors below 5%, whereas 

favorable sites can have factors as high as 20%. 

Target First Year Seedling Density – The target fi rst year density is the number of plants/ft2

desired the fi rst year after sowing (Line F of Figure 10.96). Establishing target density factors is 

often based on the objectives of the project. For example, projects where the objective is fast 

plant establishment for either erosion control or weed prevention would usually require the 

target fi rst year densities to be relatively high. Target densities are also based on the growth 

habits of the species to be sown. Fast-growing species with large spreading growth habits 

would have low target densities. Shrubs and trees would have target fi rst year densities of less 

than 1 plant/ft2, whereas grasses might have densities up to 25 seedlings/ft2. Monitoring sites 

after one year can give a good indication of what densities can be expected from each species 

and what densities are most appropriate for meeting project objectives. 

It should be recognized that there is a point of diminishing returns, where applying more 

seeds does not necessarily produce more seedlings. There is a limit to how many seedlings can 

survive on a site, and no amount of seeds applied will change this fact. While applying excess 

seed errs on the conservative side, it can be wasteful and costly. It can also favor the aggressive 

species over the less aggressive species (Monsen and Stevens 2004). When using high seeding 

rates, it is important to reduce the ratio of aggressive species to non-aggressive species in order 

to assure that non-aggressive species can become established.

Target Composition – The target composition is the proportion of each species that will 

comprise the seedlings found in a given area (Line G of Figure 10.96). An example of a target 

seed mix composition is one that would produce a stand of grass and forb seedlings made 

up of 35% blue wildrye (Elymus glaucus), 35% California fescue (Festuca californica), and 30% 

common yarrow (Achillea millefolium). See Section 10.3.1.4 for further discussion.

Area to Seed – The area to seed is the total acreage of a seeding area to which a seed mix will be 

applied (See Section 10.3.1.2 for a discussion on how seeding areas are determined.)

10.3.1.6 Prepare Seed Mixes

Once sowing calculations are completed for each species, seed mixing operations can begin. 

The objective of these operations is put together seed mixes in packages that are organized, 

easy to handle, and ready to use. This is an important step, because there can be no room 

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Table 10.16 – First year seedling 

survival is dependent on the quality of 

the germination environment. This table 

is a guide to setting fi rst-year survival 

rates based on factors that infl uence 

germination. High fi rst-year survival 

rates might be closer to 20%: low 

survival is often less than 5%. 

Seed cover none

Low

Estimated Field Survival

High

mulch

Spring rainfall low high

Humidity low high

Water-holding capacity low high

Sowing method poor good

Season sown fall spring

Seed treatments poor good

Freeze thaw high low

Surface erosion high low

Aspect south north

Fertility low high

309
for confusion in seeding operations 

or time for reorganizing seed mixes. 

The seed mixing operation involves 

weighing seeds from each species 

or seedlot, mixing seedlots, placing 

seeds in bags, and labeling. 

The seed bag is the basic handling 

unit used in seeding. Before mixing 

begins, you must determine how 

much area a bag of seed mix will 

cover. This will depend on the seeding 

method. For hydroseeding contracts, 

the seed bags can be no larger than 

the area a slurry unit will cover (See 

Section 10.3.2). For example, if a 1,000 

gallon hydroseeder tank covers a 

quarter acre, then the bags of seed 

mix would have enough seeds to 

cover a quarter acre. In this example, 

the seed mix is divided into four bags 

per acre (Line L of Figure 10.96). The 

most typical seed bag coverage is 

a quarter of an acre because of the 

increased fl exibility, reduced weight, 

and ease of handling. 

The sowing method is an important 

factor in assembling the seed mix. 

If the mix is to be used in a seed 

metering system (Inset 10.19), 

each seedlot must be thoroughly 

mixed together to ensure a uniform 

distribution of seeds of each species 

on the site. On the other hand, if the 

seed mix is placed in a hydroseeder, it 

is not necessary to mix the seeds since 

all seeds will eventually be mixed in 

the hydroseeder before application. 

Other packaging will be required if 

more than one seedbox is used (e.g., 

the Truax® seed drill).

Other materials can also be included 

in the assembly of the seed mix. 

Mycorrhizal inoculum can be mixed 

with the seeds, as well as dyes to 

make seeds easier to see after seeding. Mycorrhizal inoculum and dye will change the rates that 

seeds will fl ow. Seed metering systems will have to be calibrated for these materials. Very smallseeded species may need to be sown with carriers, such as rice hulls (Stevens and Munson 

2004). For small, fl uff y seeds, wheat bran can be added to help prevent them from migrating 

upward in the seed mix (Dixon and Carr 2001b).

When calibrating seeds for mulch blowing operations, it will be necessary to create more small 

seed bags that represent smaller calibration areas (Inset 10.20).

10.3.1.7 Determine Seeding Date

The best date to sow varies by site, but typically it is in the fall. On cool, arid sites, seeding later 

in the fall is better to prevent premature germination prior to the onset of the winter (Monsen 

and Stevens 2004). On warm, moist sites (e.g., the west side of the Cascade Mountains), sowing 

can take place in the late summer and early fall, anticipating that seeds will germinate with 

early fall rains and become established prior to winter. If seeds are sown in the spring or early 

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Inset 10.19 – Seed Metering and Delivery 

Systems

The seed metering system is key to uniform 

application of dry seed mixes. Seed boxes should 

contain a mechanical seed agitator (as shown 

in picture) that constantly mixes the seeds to 

prevent seed bridging. The rate of seed fl ow 

must also be easy to adjust to allow for changes 

in sowing rates. Some systems, such as those 

found on mulch blowers, have remote controls 

that allow the applicator to turn the metering 

system on and off . 

There are several types of seed delivery systems 

available, and the choice of the system will 

depend on project objectives. Some systems 

have more than one seed box to keep several 

species separate. This might be necessary when 

working with seed mixes that include chaff y or 

fl uff y seeds. Specialized seed boxes that are 

manufactured with a semicircular seedbox, 

auger agitator, and pickerwheel, as developed by 

the Texas Agricultural Experiment Station (USDA/

USDI 2005), can be used for these types of seeds. 

Drilling diff erent sized seeds may also require 

two or more seed boxes. The Truax® seed drill has 

three seedboxes that are adjusted to sow various 

seed sizes and shapes. 

310
summer, seed mixes should be composed of species that germinate quickly and do not require 

a long natural stratifi cation period.

10.3.1.8 Assure Quality

There are several factors to monitor during seeding to assure operations are administered 

correctly. Depth of seed placement, uniformity in application, target seed densities, and seed 

handling must be monitored throughout the process. It is important to periodically measure 

seed depths, especially at the beginning of the operation or when any new site being seeded. 

Seed dyes are sometimes applied to make seeds more visible. However, these are not useful 

when seeds are applied through hydraulic seeders or mulch blowers. Uniformity of seed 

application can be monitored as seeds are being distributed through seed metering or delivery 

systems. Sometimes seed systems plug or malfunction, resulting in sporadic application of 

seeds. Poorly applied seeds, where the applicator either misses spots or applies over seeded 

areas, will also results in an uneven application.

Seed densities can be monitored indirectly by measuring the area where a known weight of 

seed has been applied and matching it to the estimated acreage it was targeted to cover. For 

example, on a project where a seed mix is split into a quarter-acre bags, the area seeded with 

one bag of seed mix would be measured. If a quarter-acre bag covered only 0.2 acres, the seed 

was sown more thickly and the density was increased by 25% (0.5/0.2). If the seed bag had 

been applied over 0.30 acre, the seeds would have been spread across more area and the seed 

density would have decreased by 17% (0.5/0.3). These measurements should be done as each 

seed mix is being applied. If there is a signifi cant change in density, adjustments to the seeding 

operations can be made.

Measuring a seeding area unit is important not only for determining if seeding rates are 

being applied correctly, but also for accurately paying the seeding contractors. Contract 

administrators should be measuring the area that each seed bag or known seed quantity is 

being sown during, or immediately after, seed application. Figure 9.2 in Chapter 9 describes 

a method to measure area by measuring the slope length that has been seeded at each road 

station marker and multiplying it by the distance between markers. 

Proper seed handling should also be monitored. Seed bags should stored in suitable 

conditions and always handled with care. Seed bags should not be thrown or dropped or left 

in unsuitable conditions. 

10.3.2 HYDROSEEDING

10.3.2.1 Introduction

Hydroseeding is a method of hydraulically applying seeds, stabilizers, and soil amendments 

to the surface of the soil for the primary objective of revegetation. The term hydromulching 

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Inset 10.20 – Calibrating Seed Densities for Mulch Blowing

Calibrating seed metering systems on mulch blowers to obtain the target seed density can 

be accomplished by laying out several plots of identical area (e.g., 1,000 square feet) with 

fl agging. The seed required for each plot is determined and measured:

seed weight = plot area (sq ft) * (target pounds of seed mix/acre) / 43,560.

For example if the seed mix application rate is calculated at 30 lb/ac and the plot size is 

1,000 ft2, the weight of seed to apply per plot is 1,000*30/43,560, or 0.69 lb. Make at least 6 

seed calibration bags. Prior to applying mulch, place the seeds from the calibration bag into 

the seed metering bin. Apply the mulch to the plot at the target depth while one person 

monitors the seeds being metered out. When all seeds are dispensed, stop the application 

and estimate the area covered by mulch. If the mulched area was approximately half of the 

1,000 ft2 plot (500 ft2), the seed densities would have been doubled. Adjustments to the 

seed metering controls would need to be made to deliver 50% of the seeds. After these 

changes are made, mulch would be applied to another plot to determine if seeding rates 

were closer to the target rates. 

311
is often used interchangeably with hydroseeding, but there is an important distinction; 

hydromulching is the application of hydraulic mulch and surface stabilizers for the primary 

purpose of erosion control. Hydromulching is typically conducted on multi-year construction 

projects, when surface soils need to be temporarily stabilized for soil erosion or dust 

abatement. While hydromulching and hydroseeding operations both must stabilize the soil 

surface, hydroseeding has the additional and overriding goal of placing viable seeds in a 

surface environment to germinate and grow into healthy plants. Meeting the dual objectives 

of erosion control and plant establishment in one operation is often a balancing act. The best 

methods for soil stabilization are not always optimal for seed germination and plant growth. 

In this section, we will focus on hydroseeding, not hydromulching. We will discuss how to best 

meet the needs of early plant establishment using hydraulic sowing methods and leave the 

discussion of stabilizing the surface through hydromulching to the many articles on this subject 

and to the manufacturers of these products.

Hydroseeding equipment is composed of: 1) a tank that holds a slurry of water, seeds, soil 

amendments, and stabilizing products; 2) paddles or agitation jets in the tank to mix the slurry; 

3) a high pressure pumping system; and 4) a hose and nozzle (Figure 10.97). 

Tanks come in a variety of sizes, from a few hundred to over 3,000 gallons. As the size of the 

tank increases, the speed and effi ciency of the operation improves. Because the travel time is 

the same for any size hydroseeding unit, the farther the water source is from the project site, 

the more effi cient larger tanks become. 

The hydroseeding tank is analogous to a large mixing bowl fi lled with various ingredients 

and blended together with water to make a slurry. Typical hydroseeding ingredients fall into 

these categories:

 · Seed,

 · Hydraulic mulch,

· Tackifi er,

 · Fertilizer,

 · Soil amendments, and

 · Dye (typically in the hydraulic mulch).

The mixture of ingredients is called a slurry. When a slurry is applied to an acre, it is referred to as 

a slurry unit. The quantity of each material added to a slurry tank is only limited by the ability of 

the mixture to be pumped through a hose and shot through a small nozzle without clogging. The 

tank can only hold so much material before the mixture becomes too thick to pump. Finding the 

right mix and rates of ingredients is important for effi cient use of the equipment. The applicators 

and manufacturers of these products can recommend optimum product rates. 

Hydroseeding ingredients must be thoroughly blended prior to application to achieve uniform 

seed coverage. There are two types of hydroseeding mixing systems – those that mechanically 

stir and those that mix using a hydraulic jet. The fi rst system employs rotating paddles to blend 

the slurry in the tank and a centrifugal pump or positive displacement gear pump for slurry 

delivery. The second system uses a centrifugal pump to both agitate the slurry and deliver the 

slurry to the site.

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Figure 10.97 – The hydraulic seeder 

is composed of a tank that holds and 

mixes a slurry, and a pump system that 

moves the slurry through a nozzle for 

application to the soil surface.

312
During application, the slurry is pumped to the nozzle for application. The applicator has a 

choice of nozzles, use of which depends on the site and slurry conditions. Slurry application can 

be from a “gun” mounted on the top of the hydroseeding unit or from a hose pulled manually 

to the application site. Stationary application (using a hydroseeding gun) is accomplished 

where the hydroseeding equipment can easily access the site. These areas are typically cut 

slopes and fi ll slopes. Depending on the consistence of the slurry, the pumping system, and 

wind conditions, slurry can be shot 200 feet or more. Hoses are laid out for sites that cannot be 

reached this way. Depending on the diameter of the hose and the pumping system, hoses can 

reach sites over 300 feet from the hydroseeding unit.

Hydroseeding is used when other seeding methods are impractical (See Section 10.3.1, Seeding). 

Typically, these are steeper sites where ground based seeders are limited. Hydroseeding has 

the advantage over other seeding methods of applying soil amendments, fertilizers, soil 

stabilizers, and seeds together in one operation, making this a one pass operation. In addition, 

seeds that are used in hydroseeding operations do not have to be as clean (that is, free of straw, 

awns, chaff ) as for other seeding methods. This can reduce costs and time associated with seed 

cleaning operations.

The time it takes to hydroseed is a function of the size of the mixing tank and the amount of 

hydraulic mulch that is applied on a per acre basis (Figure 10.98). The greater the amount of 

hydraulic mulch applied per acre, the longer it will take. For example, it takes almost twice as 

long to apply 2,000 lb/ac of hydraulic mulch through hydroseeding equipment as it does to 

apply 1,200 lb/ac. For this reason, determining the appropriate amount of hydraulic mulch is 

important from a cost standpoint. Cost includes not only the costs of purchasing the product, 

but also the time to apply it. Tank size is also an important factor in application rates; the larger 

the tank size, the less application time it takes. A 3,000 gallon mixing tank for example, takes 

less than half the time to cover an acre than a 1,000 gallon tank. 

Hydroseeding in wildland revegetation has a number of limitations (Stevens and 

Monsen 2004):

1) Seeds are not placed in the soil

2) Seeds and seedlings can dry out

3) Some seedlings cannot grow through the hydraulic mulch

4) Seeds can be damaged by agitators and pumps

5) Precocious germination can occur as a result of moisture in the hydraulic mulch

6) Hydroseeding requires large quantities of water

With good planning, implementation, and monitoring, many of these limitations can be 

managed, resulting in successful revegetation. Ultimately, the success of any hydroseeding 

project comes down to the availability of water during germination and seedling establishment. 

Hydroseeding is successful in the landscaping business because seeds are irrigated after 

hydroseeding until a stand of grass has become established. As one applicator stated, “what 

people don’t understand is you can do the best hydroseeding job in the world but if they don’t 

water it, it’s not going to grow” (Brzozowski 2004). The challenge in wildland revegetation is 

that, for most projects, irrigation is not available. To make hydroseeding successful, strategies 

must be developed that maintain moisture around the seeds and in the soil during early 

plant establishment.

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Figure 10.98 – Hydromulch application 

time can be roughly calculated from 

the size of the mixing tank and the 

application rate. Cycle time (the time 

it takes to drive from the water source 

to the spray area, discharge the slurry, 

and return) used in this analysis was 60 

minutes for a 3,000 gallon tank and 45 

minutes for a 1,000 gallon tank (fi gure 

modifi ed after Trotti 2000).

1,000

Tank Size

Mulch Rates (lb/ac)

Hours per Acre

3,000

1,200

5

4

3

2

1

0

1,600 2,000

313
10.3.2.2 Integrate Hydroseeding into Revegetation Strategy

From a revegetation standpoint, hydroseeding serves as: 1) a method of seed placement, 

2) a means of stabilizing the soil surface for controlling erosion and to allow seedlings to become 

established, and 3) a way to apply fertilizers and other soil amendments. These objectives 

cannot always be met in one hydroseeding operation. It often requires that each objective be 

considered independently, and then integrated into an overall strategy. Clarifying objectives, 

based on the site specifi c conditions of the project, and determining the best way to achieve 

them using hydroseeding equipment as part of the approach, will lead to the best revegetation 

results. For example, seed placement and fertilizing are diff erent objectives, yet meeting 

both objectives is often accomplished in one hydroseeding operation out of convenience. 

However, the best time to apply fertilizers on many projects is after the seeds have germinated 

(See Section 10.1.1). Instead of meeting fertilizer and seeding objectives in one hydroseeding 

operation, separating them into two diff erent applications would be a better strategy for 

meeting overall project objectives. 

On a site with high surface rock, for example, the main objective would be seed placement. 

Little importance would be placed on surface stabilization since the rock has already created 

a stable surface. The best potential sites for seedling germination on this harsh surface would 

be between the surface coarse fragments, where seeds are protected and moisture collects. 

Yet a common mistake that occurs in many hydroseeding projects is to include the same rates 

of tackifi ers as would be used on a soil surface. Under these circumstances, tackifi ers adhere 

seeds to the rock surface, preventing the seeds from washing between the gravel and cobbles 

that cover the surface. The objective of stabilizing the surface is not only unnecessary in this 

example, it would negatively aff ect placement of seeds.

Hydroseeding should always be accomplished within a strategy of creating an optimum seed 

environment. The hydroseeding operation places seeds on the surface of the soil which is often a 

poor environment for germination. Hydraulic mulch is inferior to long-fi ber mulches in reducing 

surface temperatures, maintaining soil moisture, and moderating surface temperatures (See 

Section 10.1.3). The term “hydraulic mulch” is misleading because most materials that fall into 

this category lack many of the important properties associated with mulches (See Section 

10.3.2.5). By their nature, hydraulic mulches are more like a growing medium than mulches 

because of their capacity to absorb water (Most hydraulic mulches hold greater than 1,000 times 

their weight in water).As a growing medium, hydraulic mulch maintains high moisture around 

the germinating seeds. But once the hydraulic mulch dries out, which is often very quickly on 

dry sites, it no longer protects the seeds from drying as a mulch would and germination rates 

are compromised. 

The literature is scant and inconclusive on the benefi ts of hydraulic mulch to seed germination 

and seedling establishment in wildland conditions. Carr and Ballard (1980) found no diff erence 

in plant establishment when seeds were applied with and without hydraulic mulches, but only 

low rates of hydromulches were compared. One approach to increasing seed germination that 

is often used in drying climates is a two pass application system, where seeds and a minimum 

amount of hydraulic mulch are applied in the fi rst pass, then covered by a thick application 

of hydraulic mulch in a second pass. While this application method appears to have some 

advantage over a one pass operation because the seeds are covered with a greater thickness of 

hydraulic mulch, it is not known what the diff erence in germination and seedling establishment 

rates might be. The benefi ts from a germination standpoint are probably not seen until the 

hydromulch rates are high (3,000 lb/ac or greater). Even then, on arid sites receiving less than 6 

inches precipitation, higher hydraulic mulch rates can intercept the low amount of precipitation 

that is received, preventing moisture from reaching the seeds (See Section 5.2.2). Since it is 

uncertain whether hydraulic mulches improve germination, it is better to base mulch rates on 

surface stability objectives than on seeding objectives and use other methods to improve seed 

germination. For example, it might be more eff ective to reduce the amount of hydraulic mulch 

to the minimum amount necessary to apply seeds and, with the costs savings, apply a longfi bered mulch in a second operation.

10.3.2.3 Identify Hydroseeding Areas

Hydroseeding should take place after the fi nal slope shaping and topsoil placement have been 

completed. Several months before hydroseeding is to take place, the site must be visited to 

fi nalize an implementation plan that includes the locations of where the plants or cuttings are 

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314
to be installed and where seeding will take place. While most of the hydroseeding areas will 

conform to the revegetation units developed during planning, things always look diff erent 

after construction. In this fi eld review, the exact locations of the areas that will be hydroseeded 

are drawn on a road map and areas are identifi ed where diff erent seed mixes, fertilizer types/

rates, or hydraulic mulch rates will be applied.

The acreage for each hydroseeding area is calculated using methods described in Figure 9.2 

in Chapter 9. This method partitions the cuts lopes and fi ll slopes into rectilinear units by road 

stations and calculates acreage between each unit. This information is then summarized in a 

hydroseeding table (shown in Figure 10.107) that is used to develop task orders. It can also be 

used in the fi eld for keeping record of acreages and location of hydroseeding operations.

The proximity to streams must be considered when locating hydroseeding areas. If 

hydroseeding areas are adjacent to ditches or waterways that drain into live streams, a buff er 

should be included around these features to avoid entry of fertilizers into the stream system. 

Fertilizers applied to these sites have the potential of entering the ditches during rainstorms 

and eventually reach a stream course as nutrient pollution. Road runoff can be a signifi cant 

contributor of nutrients to water systems (Reuter and others 1998). 

10.3.2.4 Determine Seeding Rates

Sowing rates for hydroseeding are calculated using the same method outlined in Figure 10.96 

in Section 10.3.1. The reader is referred to this section for determining seeding rates for any 

type of sowing method. These sowing calculations assume that the method of sowing does not 

cause damage to seeds. This might not be a good assumption with hydroseeding, which has 

been shown to increase the risk of seed breakage in the hydraulic seeder tank during mixing 

(Kay and others 1977; Wolf and others 1984; Pill and Nesnow 1999). Additions of fertilizers 

further increase the risk by exposing seeds to high salt levels when seeds are in the slurry tank 

and also after they are applied to the soil surface (Brooks and Blaser 1964; Carr and Ballard 

1979; Brown and others 1983). Taking precautions to reduce the risk of seed damage during 

hydroseeding will increase the seed germination rates and reduce the amount of seed needed 

for the project. 

Considerations that can reduce the risk of damaging seeds include:

 · Type of hydraulic seeder,

 · Seed condition,

 · Duration in slurry,

 · Seed moisture,

 · Hydraulic mulch,

 · Nozzle and nozzle position, and

 · Fertilizers.

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Figure 10.99 – Grass seeds are protected 

by sets of bracts called the lemma and 

the palea (the lemma is the larger, outer 

covering, and the palea is the shorter, 

interior sheath). The awn is a fi brous 

bristle that extends from the midrib of 

the lemma. The awns for most grass 

species are removed during cleaning 

for easy sowing. The lemma and palea 

should be kept on the seeds to protect 

them from seed damage during sowing, 

especially in hydroseeding operations.

Awn

Palea

Lemma

315
Hydraulic Seeders – Hydraulic seeders that use centrifugal pumps for agitation and delivery can 

have a higher potential to damage seeds than systems with paddles and rubber-coated gear 

pumps (Kay 1972a; Kay and others 1977). Kay (1972a) found that germination of intermediate 

wheatgrass (Agropyron trichophorum [Link Richt.]) seeds was reduced from 80% (control) to 10% 

germination after one hour in a centrifugal agitation system; after two hours, germination was 

reduced to 1%. There was no reduction in germination after one hour using paddle agitation, 

but germination declined to 59% after two hours. Pill and Nesnow (1999), however, found that 

centrifugal pumps did not reduce germination rates of Kentucky bluegrass (Poa pratensis) and 

perennial ryegrass (Lolium perenne) after mixing for an hour in a slurry tank. 

Seed Condition – Grass seeds are enclosed by sets of bracts, called the lemma and palea. 

These structures provide a protective covering (Figure 10.99) and are believed to reduce seed 

breakage during hydroseeding agitation and application. In the aforementioned study, Pill and 

Nesnow (1999) believed that one of the primary reasons there was no decline in germination 

after an hour of mixing in a slurry tank was because the lemmas and paleas were still intact 

around the seeds. The association between presence of these seed structures and protection 

from seed breakage during hydroseeding should be considered when cleaning seeds for 

hydroseeding. Seed cleaning is necessary for storage and seeding (See Section 10.2.1 and 

Section 10.2.4). However, seeds for use in hydroseeding operations do not have to be as clean 

as seeds used in other seeding methods. Each species has diff erent cleaning requirements for 

hydroseeding. Some require thorough cleaning, while others might require very little cleaning. 

It would be benefi cial to discuss the level of seed cleaning for hydroseeding with your seed 

extractory personnel and seed increase contractors.

Duration in Slurry – The longer seeds are mixed in the slurry tank, the greater the potential 

for breakage. Kay and others (1977) found that after 20 minutes of agitation, seed germination 

decreased signifi cantly (Figure 10.100). For this reason, it is important to add seeds immediately 

before application. 

Seed Moisture – As a general rule, moistened seeds have less potential for breakage than dry 

seeds because they are more fl exible when impacted. Kay and others (1977) found that soaking 

seeds for 1.5 days prior to application signifi cantly increased germination over dry seeds (Figure 

10.100). Longer soaking periods (4 days) had negative eff ects on germination because radicles 

were emerging and were damaged with mixing.

Soaking seeds prior to hydroseeding will unfortunately initiate seed germination, which is not 

usually desirable for hydroseeding projects. Pill and Nesnow (1999) suggest seed priming as 

an alternative to soaking. Priming is a seed treatment that partially moistens seeds without 

initiating seed germination (Pill and others 1997). Seed is mixed at one part seed to 10 parts 

moist vermiculite (although peat could be used as a substitute) and stored at cool temperatures 

for up to 10 days prior to hydroseeding.

Hydraulic Mulch – Hydroseeding without hydraulic mulch can increase seed damage (Kay 

1972a, 1978). Using a minimum rate of 500 lb/ac hydraulic mulch is suggested for protecting 

seeds (Kay 1978).

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Figure 10.100 – Using a centrifugal 

hydroseeding pump system, Kay 

and others (1977) found a reduction 

in germination of Bermudagrass 

(Cynodon dactylon) seeds after 

20 minutes in the slurry tank. Seed 

germination improved when the 

seeds were soaked in water for 1.5 

days prior to placing in a hydraulic 

seeder tank. However, soaking 

for longer than 1.5 days reduced 

germination more than if the seeds 

were not soaked (modifi ed from Kay 

and others 1977).

100

90

80

70

60

50

40

30

20

10

0

0 10 20 30 40 50 60

1.5 Day Soak

No Soak

4Day Soak

Minutes in hydroseeder

% Germination

316
Nozzle Type and Nozzle Position – Shooting slurry straight at the soil in close range can 

damage seeds. The impact at high speeds can cause seed coats to break. As one hydroseeding 

operator describes the action, “we just shove that seed right smack in the ground with a lot of 

force...the gun was slamming straight to it” (Brzozowski 2003). Describing this action to a Forest 

Service seed extractory specialist, his reaction was, “that can’t be good for the seed” (Barnar 

2007). In the seed production and seed extraction businesses, handling seeds carefully is a high 

priority. This attitude and practice should not stop with the seed producers, but follow through 

to the application of seeds. One application practice that could reduce seed damage is to aim 

nozzles so the slurry is not hitting the soil surface with full force at close range. Arching the 

slurry stream so the spray hits with lower force is more desirable. Using less pressure or lower 

pressure nozzles, such as fan nozzles, can also reduce seed damage (Figure 10.102). Some soils 

are very loose or powdery after construction, which can cushion the seeds, as opposed to very 

compacted surfaces. Seeds applied to these surfaces can be buried under the loose soil when 

the slurry is shot straight at the surface, off setting the eff ects of seed breakage and increasing 

germination potential (Mast 2007).

Fertilizers – Adding fertilizer to the slurry can reduce germination of certain species due to the 

eff ects of fertilizer salts on seed imbibition, or uptake of water (Brooks and Blaser 1964; Carr 

and Ballard 1979; Brown and others 1983). This is not just a problem when seeds and fertilizers 

are mixed together in the slurry tank; it can also negatively impact the seeds after they are 

applied to the soil surface and before the fi rst rains dilute the surrounding salts. Eff ects of 

fertilizer salts will be more detrimental on sites with low rainfall. Carr and Ballard (1979) found 

white clover (Trifolium repens) and, to a lesser degree, Festuca spp. had the greatest reduction 

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Figure 10.102 – Hydraulic seeders are equipped with several types of nozzles. The nozzle shown 

in photograph (A) shoots long, high pressure, streams while the fan nozzle shown in (B) spreads 

the slurry out for closer applications.

A B

Figure 10.101 – Incorporating 

10-30-10 fertilizer into hydroseed 

slurries can reduce the germination of 

some species (Carr and Ballard 1979).

Without Fertilizer

Trifolium 

repens

% Germination

Festuca 

rubra

Lolium

perenne

Festuca 

arundinacea

100

90

80

70

60

50

40

30

With Fertilizer

317
in germination. They suggest white clover should be applied by hand, separate from the 

hydroseeding operation. 

Assuming that most native seeds, especially legume species, are aff ected by fertilizer salts, it is 

important to understand what the eff ects of diff erent types and rates of fertilizers will have on 

the salt concentrations in the slurry. Brooks and Blaser (1964), Carr and Ballard (1979) and Brown 

and others (1983) used inorganic, fast release fertilizers, which dissolve quickly in solution (See 

Section 10.1.1). Organic and control release fertilizers, on the other hand, dissolve slowly and 

therefore should have lower salt levels in solution. Whichever fertilizers or rates are used, 

testing the slurry for soluble salts should be conducted to assure that concentrations are not 

lethal (See Section 5.5.5).

The eff ect of hydroseeding operations on seed viability is an important issue and deserves 

more research attention. Monitoring information can be used to broaden our understanding 

on how to properly use this important tool. 

10.3.2.5 Select Hydraulic Mulch and Determine Rates

Hydraulic mulch is a low bulk density material applied through a hydraulic seeder to increase 

surface soil strength and reduce erosion. At high application rates, seeds are covered, thereby 

increasing the potential for increased seed germination. Commercial hydraulic mulches 

are derived from wood fi ber, recycled paper (wood cellulose), sterilized grass straw, or a 

combination of the three. Wood fi ber mulches are manufactured from wood chips thermally 

treated by a steam and high pressure shredding process; wood cellulose mulches are made 

from waste paper materials such as recycled newspaper and cardboard (Trotti 2000). Hydraulic 

mulches typically have very high water-holding capacities (over a 1,000 times their weight 

in water). A pound of wood fi ber mulch, for instance, absorbs between 1.5 to 2.5 gallons of 

water and, inversely, a gallon of water holds between 0.40 and 0.66 lb hydraulic mulch. This 

is important information to know when determining how much hydraulic mulch to add to a 

slurry tank. Most operators will not exceed a ratio of 0.4 to assure they do not clog their system 

with a slurry that is too thick. At this proportion, a 1,000 gallon tank would hold 400 pounds of 

wood fi ber mulch. Product specifi cation sheets should indicate the ratio of hydraulic mulch to 

water for hydroseeding equipment.

The depth and cover of hydraulic mulch depends primarily on the quantity and properties of 

the mulch placed in the tank. Typical hydroseeding projects range in application rates from 

500 to 3,000 lb/ac. At low application rates (<1,000 lb/ac), wood fi ber mulch will not cover the 

entire soil surface, leaving most seeds and much of the soil surface exposed. At high rates 

(>3,000 lb/ac) the soil surface and seeds are usually completely covered (Figure 10.103). With 

the appropriate mix of tackifi ers, hydraulic mulch rates above 3,000 lb/ac can bond together 

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Figure 10.103 – Hydraulic mulch 

applied at high rates and with 

specialized tackifi ers will hold together 

as a sheet and is referred to as a “bonded 

fi ber matrix,” or BFM. The application rate 

of wood fi ber mulch in this picture was 

3,000 lb/ac.

318
to form a continuous sheet, called a bonded fi ber matrix, or BFM. A bonded fi ber matrix will 

stabilize seeds and control surface erosion up to a year after application. 

The length of the wood or cellulose fi bers is an important characteristic in creating a soil cover 

mulch that does not restrict seed germination or plant growth. Cellulose mulches have shorter 

fi bers than wood fi ber mulches and, because of this, these materials compact much easier 

when they are applied. Applying too much cellulose mulch can result in a soil surface that 

has the consistency of “paper mache.” At application rates greater than 1,500 lb/ac cellulose 

mulch, there is a reduction in infi ltration and air exchange, and seed germination and seedling 

establishment are decreased (Gassman 2001). Some manufacturers have overcome this 

problem by mixing straw, a long-fi bered material, with paper mulch. Typically, cellulose mulch 

requires 20% to 40% more material to achieve the same uniformity of coverage as wood fi ber 

mulch (Trotti 2000) (Figure 10.104). While recycled paper mulches are typically less expensive 

than wood fi ber, the cost savings are partially off set by the increased amount of paper mulch 

used. Blended mulches (those with equal portions of wood fi ber with recycled paper) are an 

eff ort to improve the characteristics of recycled paper by adding wood fi ber.

The use of hydraulic mulch for seed germination becomes less important on wetter sites, 

especially in climates where there is little soil drying during germination (Carr and Ballard 

1980). These conditions are found from fall through early spring on many sites in the Coast 

Range and Cascade Mountains, and microsites that include north aspects and sites shaded by 

vegetation. On these sites, 1,000 lb/ac or less might be suffi cient for seed germination. In areas 

with high rainfall and erosive soils, higher hydraulic mulch rates or even a bonded fi ber matrix 

might be needed to keep seeds and soil in place until seeds have germinated and grown into 

established seedlings.

10.3.2.6 Select Tackifi er

Tackifi ers are sticking agents that bind soil particles together and protect the surface from wind 

and water erosion. When applied with hydraulic mulch, tackifi ers increase the eff ectiveness of 

the mulch as a soil cover by binding the hydraulic mulch fi bers and the surface soil particles 

together. Tackifi ers create water-stable surfaces, which means they are capable of repeated 

wetting and drying and do not lose strength after a series of rainstorms. Hydraulic mulch and 

tackifi ers can remain eff ective even through a winter with high precipitation (Figure 10.105).

Selecting a tackifi er can be diffi cult. There are numerous commercially available products on the 

market from which to choose. Unless you have used these products side by side in the fi eld, it 

is diffi cult to know the diff erence. A hydraulic seeder operator can off er advice on tackifi ers and 

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Figure 10.104 – The slurry tank can hold only so much material before the slurry becomes too 

thick to pump through the system. This graph gives a general relationship between the size 

of the slurry tank and the maximum amount of hydraulic mulch it can hold (modifi ed from 

http://www.bowieindustries.com). 

Since virgin wood fi ber mulch holds 

more moisture than paper mulch, 

less virgin wood fi ber mulch can be 

added to a slurry tank. For a project 

utilizing a 3,200 gallon slurry tank 

(A), a maximum of 1,500 lb virgin 

wood fi ber mulch (B) can be placed 

in the tank with 150 lb guar tackifi er 

(C). Guar tackifi er rates are based 

on a ratio of 1:10 guar to wood fi ber 

mulch. At a prescribed rate of 1,000 

lb/ac of wood fi ber mulch, this slurry 

tank will cover approximately 1.5 ac. 

If the application rate is 3,000 lb/ac 

virgin wood fi ber mulch, it will take 

2 tanks. Slurry Tank Size (gallons) Pounds per Slurry Tank 1,600

1,400

1,200

1,000

800

600

400

200

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500

A

C

B

Paper

Virgin Wood Fiber:

manufacturing rates

Virgin Wood Fiber:

operational rates

Guar Tackifier

319
other hydraulic seeding products, 

since they have tried a variety of 

products and would usually have a 

good idea of eff ectiveness. 

There are two general types 

of tackifi ers commonly used in 

hydroseeding – organic and synthetic. 

Organic tackifi ers are derived from 

plant materials which include guar, 

plantago, and other plant starches. 

Synthetic tackifi ers are manufactured 

polymers and copolymers that include 

polyacrylamides (referred to as PAM), 

acrylic polymers and copolymers, 

methacrylates and acrylates, and 

hydro-colloid polymers. Organic 

tackifi ers break down biologically and 

are typically eff ective for at least three 

months, depending on site conditions 

and product type. Synthetic tackifi ers 

are photo and chemically degradable 

and have somewhat greater longevity 

than organic tackifi ers, lasting up to a 

year on many sites (CASQA 2003b). 

Revegetation specialists and operators usually develop a preference for tackifi er products based 

on: 1) ease of handling and storage, 2) ease of application, 3) toxicity to plants, 4) environmental 

concerns, 5) weather restrictions, and 6) application rates.

Handling and Storage – Tackifi ers are available as dry powder or liquid formulations. Most 

organic and some synthetic tackifi ers are packaged as dry powders. These products are easy 

to handle and store because they weigh less and have less bulk than liquid containers. Liquid 

tackifi ers must be stored in areas that will not freeze if stored over the winter. Handling and 

disposal of plastic containers is also a consideration when using liquid tackifi ers.

Ease of Application – An important property of tackifi ers is viscosity. Viscosity is the measure 

of the “stickiness” of a tackifi er, or the propensity of the tackifi er to hold a slurry together when 

it is applied. Tackifi ers with high viscosity, such as guar based tackifi ers, will hold the slurry 

together as a fi ne stream when pumped from the nozzle (Figure 10.106A), and the stream of 

slurry will shoot farther. When a slurry with high viscosity hits the soil surface, it sticks and does 

not easily run off . A slurry with low viscosity, on the other hand, will separate as it is comes out 

of the nozzle and drift, especially if there is a breeze, resulting in uneven application (Figure 

10.106B). If low viscosity slurries are applied at rates that are greater than the soil infi ltration 

rates, the slurry will run off the surface. Not only will seeds be lost, but other materials in 

the slurry (including fertilizers) have the possibility of moving into surface drainage systems

(Figure 10.106C). 

Tackifi ers act as lubricants and create less friction through the hydraulic equipment. With high 

viscosity tackifi ers, equipment runs smoother and nozzles do not plug as frequently. This will 

enhance the overall performance and longevity of the equipment.

Toxicity to Plants – One reason organic tackifi ers are sometimes preferred over synthetic 

tackifi ers is the belief that these materials are better for seed germination and seedling 

establishment. They are organic substances that break down into non-toxic compounds. While 

organic tackifi ers are sometimes advertised as being better for plant health, there is nothing 

in the scientifi c literature to indicate that synthetic tackifi ers are any more harmful or toxic to 

plant establishment than organic tackifi ers.

Environmental Concerns – There have been concerns about the use of polyacrylamides (PAM) 

on human health and the environment. Acrylamide, a known neurotoxin to humans, is the 

main ingredient of this polymer. Polyacrylamides alone have low toxicity – LD50 of 5,000/kg 

oral dosage (Peterson 2002). However, in the manufacturing of the polymer, some acrylamide 

is formed. The US Food and Drug Administration has set a maximum allowable acrylamide 

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Figure 10.105 – Hydraulic mulch with tackifi ers 

remain eff ective for up to a year. This hydraulic 

mulch and tackifi er slurry was applied nine months 

prior to this picture, and was still partially eff ective.

320
content in PAM of 0.05%. While PAM 

does not appear to break down in 

the environment to acrylamide, if 

released during decomposition, it is 

thought to be quickly decomposed 

by soil microbes (Peterson 2002). 

Furthermore, since PAM degrades 

slowly in the environment, there 

should not be an accumulation of 

acrylamide in the soil (Claassen 

and Hogan 1998). Evans (2006) 

cites reviews by Barvenic (1994) on 

health hazards and Goodrich and 

others (1991) on aquatic macrofauna, 

edaphic microorganisms, or crop 

species. When polyacrylamides were 

applied at recommended rates, the 

materials were found to be safe 

for the environment. The reader 

is referred to Barvenik (1994) for a 

comprehensive discussion of PAM in 

the environment.

As with all products used in 

revegetation, a material safety data 

sheet should be requested from the 

manufacturer of the product and 

reviewed for possible human eff ects 

and eff ects to the environment. Some 

states have regulations on the use 

synthetic polymers in landscaping. 

It is important to be abreast of the 

latest environmental regulations 

(Peterson 2002).

Weather Conditions – Tackifi ers have 

limitations and conditions for proper 

application, including: soils must be 

moistened prior to application; there 

must be a 1- to 3-day drying period 

after application; the site cannot 

freeze during or immediately after 

application; or they must be applied 

between a certain temperature range. 

It is important to understand which 

environmental restrictions apply to 

the tackifi er you are using and how 

it might aff ect the hydroseeding 

operations. A site that is expected 

to be wet in the fall, for instance, 

will require a tackifi er that needs a 

minimal curing period.

Tackifi er Rates – When tackifi ers are 

used with hydraulic mulches, tackifi ers 

are applied at rates at 5% to 10% of the 

weight of the hydraulic mulch (CASQA 

2003a). Refer to manufacturer labels 

for specifi c rates. Roadside

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Figure 10.106 – High viscosity tackifi ers, mixed at 

manufacturer recommended rates, keep the slurry 

together during application using a “stream” nozzle 

(A). Low viscosity tackifi ers, or slurries with low 

concentrations of tackifi ers, do not hold together 

when applied and will drift with wind (B) or run off 

slopes (C).

A

B

C

321
10.3.2.7 Select Other Slurry Components 

The remaining components of the hydroseeding slurry can include dyes, fertilizers, 

biostimulants, and mycorrhizae.

Dyes – Dyes are used as markers for the applicator to indicate where the slurry has been applied. 

Most hydraulic mulches include dyes, so it is not usually necessary to include dyes in the slurry 

when using these mulches.

Fertilizers – Fertilizers are often applied through hydroseeders. Determining the type and 

amount of fertilizers to use is discussed in Section 10.1.1. 

Biostimulants – Biostimulants are sometimes applied to the slurry.

Mycorrhizae – Mycorrhizae are often included in the slurry (See Section 10.1.7, Benefi cial 

Soil Microorganisms).

10.3.2.8 Locate Water Source

It should go without saying that you cannot hydroseed without a water source, yet a common 

mistake is to wait until the last minute to locate a source. For many parts of the western United 

States, water sources can be long distances from the project site. It is important to establish 

early where water will be obtained for hydroseeding early in the planning process. 

Considerations when selecting a water source include:

Distance – On projects where the water source is a long distance from the hydroseeding site, 

large slurry tanks will increase the effi ciency of the operation. Conservation of water should 

be a priority in these circumstances. Covering more area with each slurry tank is one way to 

reduce water needs. This can be accomplished by applying lower rates of hydraulic mulch and 

tackifi er per acre.

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Figure 10.107 – Prior to hydroseeding, review the areas to be hydroseeded in the fi eld. For each 

road station (column C), the length of the slope (column D) that will be hydroseeded is measured 

(or estimated) and recorded. This information is placed in a spreadsheet as shown in this fi gure 

and acreage for each station is made by multiplying slope length by distance between stations 

(column E) and converting to area units (columns F and G) (e.g., acres). During hydroseeding, 

the stations and percentage of area to be covered (column B) within the station are recorded 

for each slurry tank (column A). Partial station coverage is estimated and acreages adjusted, 

as shown in the last entry in this example. When the slurry is completed, the total acres for that 

slurry tank are summed.

4 100 20+1000 27 20 540 0.133

Tank % Covered Station

Slope

Length 

(m)

Distance

between

stations

(m) Area (m2

) Acres

Acres covered by

Tank 4 = 0.95

4 100 20+1020 24 20 480 0.119

4 100 20+1040 25 20 500 0.124

4 100 20+1060 24 20 480 0.119

4 100 20+1080 25 20 500 0.124

4 100 20+1100 27 20 540 0.133

4 100 20+1120 26 20 520 0.128

4 50 20+1140 28 20 560 0.138

20+1160 23 20 460 0.114 0.069

20+1180 21 20 420 0.104

20+1200 26 20 520 0.128

20+1220 22 20 440 0.109

AB C D E F G

322
Water Quality – The quality of the water for hydroseeding must be low in salts and other 

potentially toxic compounds. If in doubt, send a sample to a water quality lab for testing or, at 

minimum, run pH and conductivity measurements on a sample.

Water Use Permits – Always check with the agency or landowner for permits to use 

their water.

10.3.2.9 Develop Hydroseeding Contract

Once a basic hydroseeding plan is developed, a contract is developed. The contract usually 

contains most of the following elements:

Site Location and Description – A general description of the site, slope gradients, location, and 

time of year the hydroseeding will occur should be addressed.

Products and Rates – The hydroseeding products or equivalent products (hydraulic mulch, 

tackifi ers, fertilizers, and so on) are identifi ed, and the rates per acre for each product are stated 

for each hydroseeding mix or mixes. The total number of acres for each hydroseeding mix must 

be tabulated.

Water Source – The location and distance to each water source are described. The contract 

should indicate whether it is the responsibility of the contractor to obtain agreements from 

owners for use or any required water permits.

Storage Area – The contractor will want a site to store hydraulic mulches, tackifi ers, fertilizers, 

and other materials associated with the hydroseeding operation. The site should be in close 

proximity to the hydroseeding areas and relatively safe from vandalism.

Equipment – If specifi c types of hydraulic seeders are required for the job, they should 

be specifi ed in the contract. Using hoses to access portions of the project site will often be 

necessary. The contract should specify how many feet of hose are needed and what percentage 

of the project will be applied by hose.

Cleaning Equipment – The contract must state that the tank and hoses will be cleaned from 

all previous hydroseeding or hydromulching projects. The equipment will be inspected 

and, if it does not pass inspection, the contractor will be required to clean equipment at an 

approved off site location.

Weather Conditions – The weather conditions, based on manufacturer specifi cations, should 

be stated. The contract should specify acceptable temperature ranges and wind velocities. It 

should also state whether rain or freezing temperatures can occur within a specifi ed period 

after application. A provision should be stated that applications will not occur on frozen ground. 

Some tackifi ers also require that the soils be moistened before application.

Mixing – The contract should state that the seeds be mixed into the slurry immediately before 

application. It should further state that the slurry must be applied within 30 minutes after the 

seeds have been placed in the tank. When the seeds are in the slurry, it should be moderately 

agitated only enough to mix the seeds and keep the slurry from separating.

Application – The slurry should be applied at a rate that covers 85% of the soil surface. Slurry 

should not run off the soil. If it does, adjustments to application speeds or nozzles must be 

made. Figure 10.102 shows the spray pattern of two types of nozzles. Avoid applying slurry at 

a range that causes slurry to splash off the surface and soil to dislodge. A two pass method is 

preferred to obtain good seed coverage. In the fi rst pass, 50% or less of the slurry is applied, 

followed by the second pass that applies the remainder of the material. Each pass is applied in a 

diff erent direction (bidirectionally), which reduces the “shadow eff ect” created by just one pass 

and may serve to better lock the matrix together (Bill Mast personal communication).

Traffi c Control – The contract must state how traffi c safety will be ensured during application. 

Will the contractor be required to supply signs, warning lights, or fl aggers?

10.3.2.10 Keep Good Records

Hydroseeding is a complex task. Not only are several products being applied at diff erent rates 

at one time, but they must be evenly applied over large complex areas. A skilled hydroseeding 

operator must be at the helm, and you must keep track of what is being applied and the acres 

on which it is being applied. This will assure that you are getting the target amount and enable 

accurate payment to the contractor.

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Inset 10.21 – Keeping Track of the Numbers

Hydroseeding might look easy, but keeping track of the numbers is not. Most hydroseeding 

operators have learned to do calculations in their heads on the run. However, unless you do 

this kind of work all the time, you probably will not be able to manage this along with the 

other requirements of being a contract inspector. As fast as this operation goes in the fi eld, 

you cannot aff ord not to have a good record-keeping system. After all, it is your responsibility 

to make sure that the contract is being fulfi lled. 

Planned Application Rates. A hydroseeding plan is developed during the preparation of 

the contract that locates hydroseeding areas and defi nes general rates of materials to be 

applied. The Table 1 shows how planning information for hydroseeding can be displayed. 

In this example, 3 hydroseeding mixes are defi ned by diff erent rates of tackifi er, mulch, and 

seed mixes in a slurry unit. Hydro mix 1 will be applied on gentle slopes requiring only a light 

covering of mulch (MulchRite) at 1,000 lb/ac. Hydro mix 2 is for steeper slopes and requires 

2,000 lb/ac mulch and more tackifi er. Hydro mix 3 is for very erosive slopes and requires 

3,000 lb/ac mulch and a diff erent seed mix. The hydro mix locations are designated on a 

road map. From this table, a total quantities list of materials for the project can be made by 

multiplying the per acre rates by the acres for each hydro mix.

Conversions to Product Units. When you are in the fi eld, you do not think in terms of 

pounds per acre because every product comes in packages. For example, MulchRite is 

packaged in 45 pound bales. To make it a simple, all rates must be converted from pounds 

per acre to product units (Table 2). 

Operational Plans. Table 3 

converts the planned application 

rates to operational loading rates 

by 1) converting “pounds per acre” 

to “product units per acre” and 2) 

converting “product units per 

acre” to “product units per slurry 

tank.” The key to these calculations 

is knowing approximately how 

many acres each slurry tank will cover. This is a function of the size of the slurry tank and 

the amount and type of mulch and other materials being mixed in each tank (See Figure 

10.104 for calculating acres per slurry tank). In this example, it was estimated that hydro 

mix 1 would cover approximately 1.5 acres. Hydro mix 2 would cover half the area (0.75 ac) 

because twice the hydromulch is being applied. Hydro mix 3 would cover one third of the

Slurry Unit (per Acre Rates)

Hydro

Mix

SlowGro

Fertilizer Seed MajiTack MulchRite MycoAlive

Reveg

Units Seedmix

1

2

3

A

A

B

4

Bags/ac Buckets/ac Bales/ac Bags/ac Bags/ac

4

4

100

200

200

1,000

2,000

3,000

10

10

10

1,900 22,500 105

1,000

1,000

1,000

10,500

2.0

5.0

3.5

A2, B1

B1

D1, D2

Acres

Total Quantities:

Table 1

SlowGro

Fertilizer MajiTack MulchRite MycoAlive

50 45 10 50

Bucket Bale Bag Bags

Pounds per

 Product Unit:

Table 2

Per Slurry Tank

Hydro

Mix

SlowGro

Fertilizer Seed MajiTack MulchRite MycoAlive

Tank Size Ac/Tank

1

2

3

1.5

0.75

0.5

6

Bags Buckets Bales Bags Bags

3

2

3

3

2.0

33

33

33

1.5

0.8

0.5

30

15

10

A

A

B

3,300

3,300

3,300

Seedmix

Table 3

324
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Keeping Track of the Numbers (Cont.)

area as hydro mix 1. The math, using the tackifi er MajiTack in hydro mix 1 as an example, is 

100 (shaded cell in Table 1) /50 (shaded cell in Table 2) * 1.5 (shaded cell in Table 3) = 3 (circled 

cell in Table 3) buckets per slurry tank. Notice the diff erence in some of the product unit 

rates, such as the “SlowGro Fertilizer.” 

Operations Diary. Table 4 covers the minimum amount of information that must be 

collected during hydroseeding operations. It captures date, time, and quantity of product 

units placed in the slurry tank. It is also a record of the acres that were covered by each slurry 

tank (See Figure 10.107 for a quick way of determining acreage). Notice that the application 

rates in this example (ac/tank) were variable, especially for Tank 2. This is not uncommon for 

hydroseeding projects. At the end of each day, Table 4 is used to summarize the amount of 

materials used each day and to track inventory. This table is the basis for contract payment.

Actual Applied Rates. Tables 5 and 6 convert what was actually applied back to pounds 

per acre to compare what was originally planned from Table 1. For example, 33 bales of 

MulchRite was applied in Tank 4 (shaded cell in Table 4). It is converted to actual pounds 

per acre as follows: 33 * 45 (shaded 

cell in Table 5) * 0.95 (shaded cell in 

Table 6) = 1,563 lbs/ac (circled cell in 

Table 6). Compared to the original 

plan, this was three quarters of the 

planned rates because the slurry tank 

was applied over a greater area than 

originally planned. For seed rates, 

this means that a quarter fewer seeds 

were applied. 

Products

Map

Unit

Ac/

Tank

Water

(gal)

Seed

Mix

SlowGro

Fertilizer Seed MajiTack MulchRite MycoAlive

Tank Date Start Finish

1

2

3

A2

A2

B1

9:15

10:10

11:20

Mix 1

Bags/

ac Buckets/ac Bales/ac Bags/ac Bags/ac

Mix 1

Mix 1

6

6

3

33

33

33

2.0

2.0

5.0

1.5

1.5

1.0

1 1 192 65 6

30.0

30.0

15.0

105

1.20

1.80

0.70

3,300

3,300

3,300

10/18/07

10/18/07

10/18/07

4 B1 1 10/18/07 3:00 0.95 3,300 Mix 1 3 3 5.0 3 1.0 15.0

5 B1 14:15

9:50

10:50

11:55

13:35

10/19/07 15:15 M 0.80 3,300 ix 1 3 3 5.0 3 1.0 15.0

Toal Quantities:

Table 4

SlowGro

Fertilizer MajiTack MulchRite MycoAlive

50 45 10 50

Bucket Bale Bag Bags

Pounds per

Product Unit:

Table 5

Products

Map

Unit

Ac/

Tank

Water

(gal)

Seed

Mix

SlowGro

Fertilizer Seed MajiTack MulchRite MycoAlive

Tank Date Start Finish

1

2

3

A2

A2

B1

9:15

10:10

11:20

Mix 1

Bags

/ac Buckets/ac Bales/ac Bags/ac Bags/ac

Mix 1

Mix 1

5.0

3.3

4.3

1,238

825

2,121

83

56

357

12.5

8.3

14.3

1,250

833

1,071

1.20

1.80

0.70

3,300

3,300

3,300

10/18/07

10/18/07

10/18/07

4 B1 1 10/18/07 3:00 0.95 3,300 Mix 1 3.2 263 1,563 10.5 789

5 B1 14:15

9:50

10:50

11:55

13:35

10/19/07 15:15 M 0.80 3,300 ix 1 3.8 313 1,856 12.5 938

Table 6

325
The records begin with the original hydroseeding prescription. These are the planned 

application rates of each hydroseeding material. It is not enough to know what you want as 

a fi nished product on the site; you must understand how it will be accomplished. This means 

that you must translate the prescribed product quantities per acre into how it will actually be 

applied. These calculations can be challenging, especially when the hydroseeding operation is 

in full swing. It is better to have some idea how this will work before you arrive in the fi eld. Inset 

10.21 is a guide through a process of determining how much of each hydroseeding material 

must go into a slurry tank. These calculations, along with the contract specifi cation, become 

the operation plans.

During the hydroseeding operations, the contract inspector must keep track of each slurry 

tank that is applied. This includes the time, amount of water, quantities of products, location, 

acreage, and weather conditions. Calculating the acreage of each slurry tank is important 

in the fi eld to assure that the rates of materials are being applied as prescribed. This can be 

accomplished using a method shown in Inset 10.21, Table 4. When this information is collected, 

the actual applied rates of materials per acre can be made using methods shown in Inset 

10.21, Table 6. This will tell you how close each slurry tank came to the prescribed rates. This is 

important feedback for the hydroseeder operator. If the application rates were off signifi cantly, 

adjustments can be made quickly. These records can be summarized at the end of the project to 

determine total quantity of materials used and the number of acres covered. This information 

can be the basis for contract payment. 

10.3.3 INSTALLING CUTTINGS

10.3.3.1 Introduction

Live cuttings have a variety of uses in revegetation projects, from stream restoration to roadside 

stabilization. When live cuttings are used as slope reinforcement, barriers to soil movement, 

or integrated into retaining structures such as rock gabions, crib walls, or rock walls, they 

form the living component of a soil biotechnical engineering system (Sotir and Gray 1992). 

In slope reinforcement, live cuttings initially play a structural role by increasing soil strength 

and preventing surface erosion. As cuttings establish into plants, soils are stabilized through 

a dense network of interlocking root systems. Soils are further stabilized during the growing 

season as soils dry due to increased evapotranspiration and rainfall interception.

Soil biotechnical engineering techniques are well documented. Gray and Leister (1982), Sotir 

and Gray (1992), and Lewis (2000) are excellent sources on road and slope stabilization, and 

the reader should refer to Bentrup and Hoag (1998) for streamside stabilization. Section 10.2.2 

discussed how to collect and evaluate live cutting quality; this section will focus on the care 

and installation of live cuttings to optimize the success of biotechnical engineering and other 

roadside revegetation projects. For simplicity, live cuttings are grouped by general application 

in biotechnical engineering projects: 1) live stakes, 2) live brush layers, and 3) live fascines.

10.3.3.2 Live Stakes

Live stakes are individual cuttings that are inserted into the slope to physically stabilize the 

soil and, with time, grow into individual plants with dense, interconnecting roots that further 

increase soil stability. Live stakes are used to repair small earth slips and slumps (Sotir and Gray 

1992) and as pole plantings for stabilizing streambanks (Bentrup and Hoag 1998). Joint planting 

refers to live stakes inserted into voids or openings between large rocks. The live stakes can take 

root and revegetate rock riprap sites or portions of fractured bedrock (Sotir and Gray 1992). Live 

stakes are also used in live fascine installations and to anchor erosion mats to the soil (Lewis 

2000). In gullies, draws, or intermittent streams, live stakes are placed in rows as live silt fences 

(Polster 1997) to slow water velocities and catch sediments and other debris. In saturated soil 

conditions, where excavation for brush layering or fascines is not feasible, live stakes can be 

densely stuck by hand.

Collection – Live stakes are collected from the main stems of donor plants located in the wild 

(See Section 10.2.2) or from stooling beds in nurseries (See Section 10.2.5). The optimum period 

to collect cuttings is during the dormant period, after the plants have lost their leaves. If cuttings 

are collected outside this period, testing the viability of the cutting material is essential (See 

Section 10.2.2.4). It is important to collect cuttings with several dormant buds because this is 

where shoots will originate (Figure 10.108).

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When preparing stakes, all side branches are removed, leaving just the stem. Only stems with 

diameters between 1 and 3 inches are used. Stems are cut into lengths of 1 to 3 feet, depending 

on how the materials will be used. It is important to select the appropriate cutting length. 

Stems that are too short will aff ect the success of the project, and cuttings that are too long 

will increase the costs of the project. During collection, basal ends of the cuttings are always 

oriented in the same direction to assure that the buds will be aligned. This will help avoid 

confusion later when the stakes are being installed. Finding the orientation of the buds is often 

diffi cult (Figure 10.108) and having to reorient in the fi eld takes time. As individual stakes are 

made, the top of the stake is cut fl at, while the basal end is cut at an angle (Figure 10.109). This 

makes the stake easier to insert into the soil and orients the live stake so the buds are facing up 

and away from the soil surface. If buds are facing down, the live stake will not root. 

During collection, live stakes are wrapped in small bundles with twine. The size of the bundle 

must be light enough to be easily carried. Once the bundle size has been determined, the 

numbers should not vary in order to track cutting quantities. Stakes should be cut from healthy 

donor plants. Stems that have obvious insect or disease damage should not be used. It is often 

easy to forget that live cuttings are plant materials, like seeds and seedlings, and must be 

handled and stored with care.

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Figure 10.108 – The vertical orientation 

of buds on older willow (Salix spp).stems 

can be visually diffi cult to discern (see 

arrows). Keeping track of the orientation 

of the bud from collection to installation 

is very important. 

Figure 10.109 – Live stakes are cut at an angle on the basal end (circle) for easier installation 

and to assure the stake is placed with buds facing up. Cuttings with buds installed upside-down 

will not develop into plants.

A B

327
Storage – It is recommended that live, dormant stakes be collected and installed the same day 

(Sotir and Gray 1992; Lewis 2000). This is not always possible in a road construction project. When 

it is not, temporary storage in Forest Service district tree coolers is an option. Temperatures in 

these facilities should be set below 40°F and, if humidifying equipment is available, it should 

be kept on high. For longer-term storage (over two weeks), cuttings should be wrapped in 

plastic or moist burlap to prevent the vegetative material from drying out and temperatures 

should be set just below freezing. Lower temperatures can result in damage and even death 

(Wearstler 2004). As a last resort, cuttings can be temporarily stored outside, provided: 1) daily 

temperatures are low (<50 °F) and humidity is high, 2) cuttings are completely wrapped in 

plastic, 3) temperatures will not drop below 25 °F, and 4) the site is shaded from the sun. 

Preparation – Studies of black willow (Salix nigra) have shown that soaking dormant cuttings 

prior to installation can increase survival (Schaff and others 2002; Martin and others 2005; 

Pezeshki and others 2005; Pezeshki and Shields 2006). Soaking for approximately 10 days 

appears to be the optimum period for black willow (Schaff and others 2002; Pezeshki and 

Shields 2006). Soaking non-dormant cuttings, however, appears to be detrimental to survival 

(Pezeshki and others 2005; Pezeshki and Shields 2006). Species native to the western United 

States might respond similarly to the black willow. The eff ects of soaking can be tested in other 

willow species using a method outlined in Section 10.2.2.4. If live stakes are soaked in streams, 

it is important to be sure they are suffi ciently protected from being swept downstream during 

high precipitation or snowmelt.

Installation – For most applications, live stakes are installed perpendicular to the soil surface. 

When installed, no more than one quarter to one fi fth of the cutting is exposed (Sotir and Gray 

1992; Darris and Williams 2001). Buds are always pointing up and away from the soil surface 

with at least two healthy buds above the soil surface. It is essential that soil be fi rmly packed 

around live stakes so there are no large air spaces surrounding the cutting. Live stakes can be 

installed using techniques described in Section 10.3.4, Installing Plants. These include a shovel, 

auger, or expandable stinger. In addition to these methods, several techniques are available 

specifi cally for live stake installation, which include a hammer, stinger, or waterjet stinger. 

Hammer or Mallet. Live stakes can be pounded into the ground using a hammer or mallet. The 

angled basal end of the stake is placed on the soil surface and the top of the cutting is struck. 

A small two by four wood block can be placed on the top to absorb the impacts and reduce 

the risk of splintering the stake. If splintering does occur, the splintered ends should be cut 

(Lewis 2000). After cutting, there must still be several viable buds above the soil surface. Using a 

hammer or mallet works best when soils are loose and low in rock fragments. It becomes more 

and more diffi cult as rock content or compaction increases. Smaller stem diameters are often 

not sturdy enough for this installation method. 

Stinger. The stinger is a good method for installing live stakes on rocky or compacted soils. A 

pilot hole is created by mechanically pushing a metal rod into the soil. A live stake is inserted 

into the hole and tamped to the bottom using a hammer or mallet, as discussed above. Some 

operators will create the hole with the stinger and, after placement of the stake, use the face of 

the excavator or backhoe bucket to push the stake further into the soil. The hole created by the 

stinger is often larger than the diameter of the stake, and the soil must be tamped in around 

the cutting to reduce air space and create good soil contact. A stinger can be made by welding 

a long piece of rebar to the bucket of an excavator or backhoe. The stinger is limited by slope 

gradient and terrain accessibility.

Waterjet Stinger. The Waterjet Stinger hydraulically creates a hole for installing live stakes. A 

pump draws water from a stream, lake, or water truck for delivery through a hose to the stinger 

nozzle. As the tip of the nozzle is pushed into the ground, high-pressure water is injected into 

the soil, creating a slurry (Figure 10.110). When the Waterjet Stinger is removed, a stake is quickly 

pushed into the resulting slurry at the desired depth. As water drains from the slurry, soil settles 

around the cutting, resulting in good soil contact.

The advantages of using the Waterjet Stinger are: 1) it is simple to operate and transport; 2) 

little training is necessary; 3) production rates are high; 4) holes are deep, assuring that cuttings 

are planted directly into a wet environment, 5) soils are saturated around the cutting for a 

long period of time; and 6) the soil slurry settles around the cutting, eliminating air pockets 

in the rooting zone (Hoag and others 2001). The disadvantage of the Waterjet Stinger is that it 

requires a source of water. If the project is not near a body of water, it can be brought in using 

a water truck or large water storage containers placed in the back of a truck (Figure 10.111). The 

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Waterjet Stinger is also limited by the amount of rock present in the soil. This equipment does 

not work well in soils containing gravels, cobbles, and boulders that obstruct the downward 

movement of the probe (Hoag 2007). Sandy soils drain quickly, so installation of cuttings with 

the Waterjet Stinger must be done quickly and with a little more eff ort. Steep slope gradients 

and rough terrain also limit equipment and the transportation of water. For more information 

on the Waterjet Stinger refer to Hoag and others (2001).

Expandable Stinger. The expandable stinger can install live stakes into all soil types and 

soil conditions, from rocky to compacted. It can plant long cuttings (> 4 ft), and stems of 

most diameters (including very small diameters). The stake is placed into the stinger, which 

is inserted into the soil and released, leaving the cutting at the desired depth (See Section 

10.3.4.3, Select Planting Tools and Methods). This installation method can leave large air 

spaces around cuttings. It is therefore recommended that soils be tamped around the cutting 

after placement. 

Hand-Sticking. Hand-sticking is appropriate in areas where soils are mucky or saturated, 

including recent landslides and wetlands, and cuttings can easily be inserted into the soil. 

Because this installation method can be done quickly, areas can be planted at very high 

densities (Figure 10.112). 

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Figure 10.110 – The Waterjet Stinger (A) injects high-pressure water into the soil, turning it to a 

slurry (B) into which a live stake can be inserted (Photos courtesy of Chris Hoag).

A B

Figure 10.111 – A 250-gallon water 

tank with pump can be installed in the 

bed of a pickup truck to supply water for 

Waterjet Stinger sticking.

329
10.3.3.3 Live Brush Layers

Live brush layers are cuttings that are spread on excavated benches and covered by soil 

(Figure 10.113). This practice is used in several biotechnical engineering applications, including 

brush layers and modifi ed brush layers. Constructing brush layers is a three-step process in 

which contour benches are excavated, live branches are spread across the bench surface, and 

branches are covered with soil from constructed benches directly upslope. The process begins 

at the bottom of the slope and is repeated until the entire slope is installed with brush layers. 

In a modifi ed brush layer system, the brush layers are resting on, and supported by, logs or live 

fascines (Sloan 2001). 

Brush layers and modifi ed brush layers increase slope stability and reduce erosion by breaking 

slope length, reinforcing soil, trapping sediment, increasing infi ltration, acting as horizontal 

drains, and reinforcing soil as cuttings develop roots (Sotir and Gray 1992). Live brush layers 

can also be used to vegetate crib walls, rock gabions, and rock walls. In this application, live 

branches are placed on benches that are created as these structures are built. For crib walls 

(Inset 10.22), live layers are placed on the bench created behind each layer of logs; in rock 

gabions, live layers are placed on each layer of gabion baskets.

Collection – Materials for live layering are obtained from branched cuttings collected in the 

wild or from stooling beds. Stems up to 2 inches in diameter can be used (Sotir and Gray 1992). 

The basal end of the cuttings are always oriented in the same direction during collection 

and bundling. Cuttings for brush layers should be long enough that the growing tips are just 

exposed at the soil surface, while the basal portion of the cuttings reach to the back of the 

bench (Sotir and Gray 1992). For rock gabions, rock walls, and crib walls, cuttings should be 

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Figure 10.112 – Hand-sticking cuttings 

at high densities is an option for 

saturated soils where the soils are too 

wet for installation of fascines or brush 

layers. This photograph shows leaves 

forming on cuttings several months 

after installation.

Figure 10.113 – Live brush layers are cuttings that are placed on benches and covered with soil 

(A). The basal end of the cuttings should extend back to the base of the bench, and the growing 

tip should just show out of the soil. When placed on the contour and at regular intervals, live 

brush layers form a network of roots and vegetation that tie the slope together in a series of 

strips, increasing slope stability and reducing erosion.

A B

330
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Inset 10.22 – When Should Seedlings 

or Rooted Cuttings be Substituted for 

Live Cuttings?

Live cuttings are widely used in biotechnical 

engineering projects. Sometimes, however, it 

is more practical to substitute rooted cuttings 

or seedlings in place of live cuttings. This is 

especially the case when the road project calls 

for cuttings to be planted in the summer or fall, 

when dormant, live cuttings are not available, 

or when live cutting material is not available in 

large enough quantities. 

For example, a road near a wild and scenic river 

is being widened. Biotechnical engineering 

techniques using live willow cuttings are 

being planned for retaining walls to increase 

slope stability in areas adjacent to the river. 

The design looks good on paper (A). However 

when discussing the details with a revegetation 

specialist, question arises: where will the 

cuttings be collected and what time of year will 

the willows be installed? Upon inventorying 

the willow stands on the district, they learn 

there is not a supply of willows great enough 

to meet the needs of the project. To obtain this 

volume and size of cuttings would require the 

establishment of stooling beds at a nursery (See 

Section 10.2.5), which would take at least two 

years prior to project implementation. More 

disturbing, they learn that the contract can only 

be implemented in the summer due to water 

quality and wildlife restrictions. While some 

cuttings installed in the summer would sprout, 

most would not, as was determined through 

rooting potential testing (See Section 10.2.2.4). 

Referring back to the project objective, the 

design engineer and the revegetation specialist 

realize that going ahead with the project, as 

designed, would compromise revegetating the 

retaining wall. The decision was made to adopt 

an alternative design to install rooted cuttings 

grown in long tubes (at a nursery) instead of 

unrooted cuttings. The rooted cuttings would 

be planted at very high densities where the 

brush layers were to be installed (Figure B). 

Since only a small amount of cuttings would be 

necessary to start rooted cuttings in containers 

at the nursery, there was no need to develop 

stooling beds, eliminating the extra time and 

costs to produce these plant materials.

The stems of the long-tube rooted cuttings 

can be set back several feet into the soil 

(see circle in Figure B) as long as a portion 

of the foliage is above ground. This will add 

length to the rooting area and the stems will 

initiate roots (C).

ABC

331
long enough to extend into soil or backfi ll behind the structures. During collection, cuttings 

are placed in bundles and secured with twine. Bundles should be light enough to carry. The 

optimum period to collect cuttings is during the dormant period, when the plants have lost 

their leaves. If cuttings are collected outside of this period, then testing the viability of the 

cutting material is essential (See Section 10.2.2.4). Fine branches dry out quickly if exposed 

to warm dry temperatures. Cuttings must be protected during transportation, storage, and 

handling to avoid drying. 

Storage – See discussion under Live Stakes, Section 10.3.3.2.

Installation – Branched cuttings are laid out on benches so the basal end of the cutting reaches 

to the back of the bench and the growing tips extend just beyond the front. Soil is placed 

over the cuttings and tamped to assure there are no large air spaces. Excessive compaction 

is unnecessary for plant establishment and is often detrimental for long-term plant growth 

(See Section 5.3.3). The material used to cover live branches in or behind crib walls, rock 

gabions, and rock walls is often low in water-holding capacity, nutrients, and organic matter. 

Soil amendments, such as compost, can be incorporated into backfi ll material to improve 

water-holding capacity and to serve as a long-term source of nutrients and organic matter. 

These amendments can increase establishment and improve plant growth (See Section 10.1.5, 

Organic Matter Amendments). Waiting until after the construction of crib walls, rock gabions, 

and rock walls to amend the soil is not practical or feasible.

10.3.3.4 Live Fascines

Live fascines are cuttings bound together to form a long continuous bundle (Figure 10.114). 

When installed on the contour, live fascines slow runoff , increase infi ltration rate, capture 

sediments, reduce slope length, and revegetate the site (Sotir and Gray 1992). Live fascines 

have a good potential for quick establishment because of the high density of buds near the 

surface of the soil. Live fascines can quickly send out shoots and roots early in the growing 

season and become established before summer (Figure 10.114). 

Fascines are used in the construction of live pole drains to drain saturated slopes, small slumps, 

or gullies (Polster 1997). Live pole drains are designed to intercept surface water from unstable 

slopes or seepage areas, and transmit it through a system of interconnecting bundles to more 

stable areas (See Section 5.7.3). The constant supply of intercepted water encourages vigorous 

growth of the cutting material into a continuous stand of vegetation. Fascines are also used 

as the base or support in the construction of modifi ed brush layers. Live fascines have great 

potential for establishment because of the high density of buds just under the surface of the 

soil. These buds can emerge quickly in late winter and early spring. Because they are installed 

at the soil surface, live fascines are more prone to drying out than live brush layers or live stakes. 

For this reason, live fascines are more successful on moist sites or in conjunction with live brush 

layering or live staking. 

Collection – Branches and stems up to 2 inches in diameter are collected from the wild or 

from stooling beds and gathered to form a long continuous bundle. Fascines vary in length 

Roadside

Revegetation

Introduction

Initiation

Planning

Implementation 

Guides

Monitoring 

& Management

Summary

Figure 10.114 – Live fascines are long bundles of cuttings placed in trenches constructed 

perpendicular to the slope. The bundles are placed in contact with the soil, with the upper 

portion of the fascine covered by a thin layer of soil (A). Fascines initiate shoots and roots in the 

spring, and are established by early summer (B). 

A B

332
from 5 to 30 ft, and from 6 to 8 inches in diameter. For large projects, constructing a series of 

sawhorse-type structures makes this operation easier and more effi cient (Sotir and Gray 1992). 

At frequent intervals, bundles are secured with twine to hold the fascines together. Cuttings 

should be collected during the dormant season, when the plants have lost their leaves. Fine 

branches dry out quickly if exposed to warm dry temperatures and must be protected during 

transportation, storage, and handling. 

Storage – See discussion under Live Stakes, Section 10.3.3.2.

Installation – Prior to installation, trenches should be created at the proper depth so the top 

of the fascine is fl ush to the surface of the slope when installed. The shape of the trench should 

allow soil contact with all portions of the bundle. Soil is tamped down around the sides of the 

bundles to assure soil contact, and the upper fi fth of the bundle is covered by a thin layer (<1 

inch) of soil. A very small portion of the fascine should be exposed, but not enough to dry the 

stems. If the fascine is buried too deeply, vegetative growth will be restricted. 

10.3.4 INSTALLING PLANTS 

10.3.4.1 Introduction

Although a wealth of information exists about planting for reforestation, very little information 

has been published about planting nursery stock on roadsides. Several references can be found 

discussing harsh site reclamation. Ashby and Vogel (1993) is an excellent source for planting on 

restored minelands.

Before beginning a planting project, the revegetation plan and plant production contract 

should be reviewed carefully, as should the Target Seedling Concept (Figure 10.115) which was 

considered during the planning process (See Section 6.4). The fi rst four steps were covered 

when plants were ordered during the planning process. The timing of the outplanting window 

and planting tools must be considered at this time. 

Timing of the Outplanting Window – The outplanting window is the period of time in which 

environmental conditions on the outplanting site are most favorable for survival and growth 

of nursery stock (Figure 10.116). The outplanting window is usually defi ned by limiting factors, 

and soil moisture and temperature are the usual constraints. In most of the continental United 

States, nursery stock is outplanted during the rains of winter or early spring when soil moisture 

Roadside

Revegetation

Introduction

Initiation

Planning

Implementation 

Guides

Monitoring

& Management

Summary

Figure 10.115 – The fi nal two steps 

of the Target Seedling Concept, the 

Outplanting Window and Planting 

Tools and Techniques, must be 

considered before initiating planting 

projects (adapted from Landis and 

Dumroese 2006).

2. Type of Plant Material

5. Timing of Outplanting Window

6. Outplanting Tools and Techniques

3. Genetic Considerations

4. Limiting Factors on 

 Outplanting Site

1. Objectives of Outplanting Project

Figure 10.116 – The best time to plant 

your project site (the “outplanting 

window”) will depend on local weather 

and soil moisture conditions. In the Pacifi c 

Northwest, this is typically during late 

winter or early spring, when soil water 

content is high and atmospheric drying 

potential is low (modifi ed from South and 

Mexal 1984).

Survival

Dec Jan Feb Mar Apr

Planting Month

Outplanting Performance (%)

Growth

Outplanting Window

333
is high and evapotranspirational losses are low. Fall outplanting is another option on some 

projects, especially when dormant and hardy plants can be installed just before the normal 

rainy season begins. Planting during the summer is usually discouraged because the nursery 

stock is not dormant and will experience severe transplant shock. If nursery stock is carefully 

handled and plants can be irrigated, then summer plantings are possible.

Planting Tools and Techniques – Nursery stocktype and the conditions on each outplanting 

site must be considered before planting begins. All too often, planters develop a preference 

for a particular planting implement because it has worked well in the past. However, no one 

tool will work for all types of nursery plants and under all site conditions. Size of nursery stock, 

in particular the depth and width of the root plug, is the critical consideration. Tall pots, for 

example, have an unusually deep root plug, which makes them diffi cult to plant properly with 

standard tools. For some types of plants and especially for large planting projects, it may be 

necessary to buy or rent specialized equipment, which must be secured in advance. The planting 

tools recommended for roadside revegetation projects are discussed in Section 10.3.4.3.

10.3.4.2 Defi ne Planting Areas

When construction is completed, the project site is assessed for planting. A detailed map 

showing the exact planting locations and conditions is developed by reviewing each location 

on the ground. Each area should be identifi ed on a map and described in a spreadsheet by: 

 · Planting area acreage,

 · Planting patterns,

 · Plant spacing (density),

 · Survival potential, and

 · Species and stocktype mix.

Roadside

Revegetation

Introduction

Initiation

Planning

Implementation 

Guides

Monitoring 

& Management

Summary

Figure 10.117 – This type of spreadsheet helps calculate how many plants of each species are 

needed and should be developed for each planting area. This example includes quaking aspen 

(POTR5), ponderosa pine (PIPO), and Saskatoon serviceberry (AMAL2), but can be extended to 

accommodate more species.

PIPO

A

B

C

D

E

POTR5 AMAL2 Units

0.75 acres

9 14 20 feet

95 70 70 %

403 167 82 plants

425 238 117 plants

2 Definition

Revegetation Unit Plant Species

Area that will be planted

Desired distance between established plants

Planting area:

Target plant spacing:

Ave. survival potential:

(43,560 * A) / (B * B) =

D * (100 / C) =

Percent of seedlings that survive after 

one growing season 

Desired number of established plants after 

one growing season

Number of nursery plants that need to 

be planted

Figure 10.118 – This spreadsheet is a 

practical way to calculate the area of 

each planting unit. 

A

1

2

Station

Slope

Length

(m)

Distance

Between

Stations

(m)

Area

(m2)

Area

(m2)

3

4

5

6

12

2 + 1000

2 + 1020

2 + 1040

2 + 1060

2 + 1080

3

4

6

7

6

20

20

20

20

20

60

80

120

140

120

7 2 + 1100 4 20 80

8

9

10

11

2 + 1120 2 20 40

B C

m2 640

Totals ft2 6,888.90

Acres 0.16

= B2 * C2

= B3 * C3

= B4 * C4

= B5 * C5

= B6 * C6

= B7 * C7

= B8 * C8

= SUM(D2:D8)

= D10 * 10.76391

= D11 / 43,560

D D

334
With this information, a planting 

strategy can be developed for each 

planting area using calculations similar 

to those shown in Figure 10.117. 

Size of Planting Areas – The fi rst 

step is to measure the area of each 

planting unit. Although they could be 

calculated from blueprints, the true 

planting areas should be measured 

on-site. A practical method is 

described in Figure 10.118.

Planting Patterns – The pattern at 

which nursery stock is planted is 

critical for creating a more natural and 

visually pleasing roadside experience. 

Most planters have learned to install 

plants at uniform spacing and in rows 

(Figure 10.119A). Although uniform 

patterns ensure that all plants have 

equal growing space, it is not natural. 

Planting seedlings in groups (Figure 

10.119B) or clumps (Figure 10.119C) 

is more visually appealing and more 

ecologically functional.

More specifi c considerations about 

planting patterns are based on project 

objectives and site characteristics of 

the area. A typical example would 

be using plants to screen potentially 

dangerous or visually sensitive 

areas, such as large cuts and fi lls or 

obliterated roads. Determining where 

trees or shrubs are to be planted to 

meet these objectives can only be 

accomplished by driving the newly 

constructed road and making these 

decisions in person.

Plant Spacing – The planting spacing 

or density (See Section 10.2.6.4) 

will determine how quickly an area 

will be screened by vegetation. 

The higher the density, the more 

plants are required. Selecting the 

appropriate density must be based 

on the existing vegetation density 

recorded at reference sites, as well 

as both short- and long-term project 

objectives. It must also be based on 

the expected survival rates of the 

planted stock, since not all planted 

stock will survive. 

Survival Potential – Each planting area must be assessed for its unique site characteristics, 

such as rock content, soil depth, accessibility, steep slopes, and poor accessibility. These will 

determine the stocktype and species selection, method of planting, and the diffi culty of 

transporting large plants to the site. The identifi ed site limitations will determine the expected 

survival rates; target survival rates should be at least 70% to minimize the costs of site 

preparation and anticipated replanting.

Roadside

Revegetation

Introduction

Initiation

Planning

Implementation 

Guides

Monitoring

& Management

Summary

Figure 10.119 – The objectives of the outplanting 

project and desired appearance aff ect planting 

patterns. If the objective is rapid growth and 

quick site coverage, the plants can be regularly 

spaced (A). However, plants spaced in a more 

random pattern mimic natural conditions (B), 

and a random clumped pattern where diff erent 

species are planted in groups is often the most 

natural appearing (C) (adapted from Landis and 

Dumroese 2006). 

A - UNIFORM

C - CLUMPED

(but groups are random)

B - RANDOM

335
Species Mix and Stocktype – Each planting area will have a diff erent mix of species and 

stocktypes based on the site characteristics and project objectives defi ned during the planning 

stages. This is a refi nement of those plans, based on site specifi c evaluation of the area. Trees 

and other large woody plants are considered “keystone species” because of their sheer size and 

longevity. These structurally and functionally dominant plants play a pivotal role in restoration 

plantings because they generate physical structure and create ecological niches for many other 

species. This fosters the in-seeding of other plants, resulting in a more natural and visually 

appealing landscape.

10.3.4.3 Select Planting Tools and Methods

One planting method will rarely work for all planting areas in a revegetation project. Roadside 

sites off er some serious challenges to planting nursery stock, most notably highly compacted 

soils and often a high percentage of rock. Road projects create the opportunity for unique 

situations such as planting islands. 

The most common type of planting method is manual planting using a shovel. Recent 

developments in mechanized planting equipment have increased tools available. The most 

common types of planting tools for roadside revegetation sites are described below:

Shovel – The versatile “tile spade” shovel (Figure 10.120A) is the fi rst choice for compacted soils 

and stocktypes used in roadside revegetation. Forestry supply companies sell a specialized 

planting shovel with a 14 by 5 inch blade, a welded reinforcement plate on the back of the 

blade (Figure 10.120B), and rubber padded footplates (Figure 10.120C). Shovels work well when 

planting both bareroot and container stock, as well as bulbs and other plant materials that do 

not require holes deeper than one foot. Working the shovel blade back and forth breaks up 

compacted soil and can create a planting hole for large container stock (Figure 10.120D). Sites 

must be accessible for hand planters, and the soils not too rocky or shallow. Very steep slopes 

(1:1 or greater) make shovel planting very slow and diffi cult. 

Power Auger – Power augers can be an excellent and effi cient way to excavate holes for planting 

(Figure 10.121A). Many types of augers are available: 1-person operated, 2-person operated, 

and a chain saw modifi cation. A wide variety of auger sizes means that this one implement can 

work for many stocktypes. Augers are particularly good for large container stock. For example, 

a four-inch auger bit will create planting holes that will just fi t the root plug of a “Tall Pot” 

container plant, ensuring good root-to-soil contact (Figure 10.121B). In a comprehensive review 

of planting tools, Kloetzel (2004) concluded that, when container size is larger than 336 ml (20 

in3), power augers will boost production under most soil conditions. It is most effi cient to have 

one person operating the auger, with several people planting behind him/her. Auger planting 

is eff ective on restoration sites because one person determines the location and pattern of 

the planting holes. Production rates are reduced with rocky or compacted soils, but a drill 

Roadside

Revegetation

Introduction

Initiation

Planning

Implementation 

Guides

Monitoring 

& Management

Summary

Figure 10.120 – Specialized “tile spade” shovels are ideal for planting a wide variety of nursery 

stock on restoration sites (A). Commercial planting shovels feature a reinforced blade (B) 

and rubber-padded footplates (C). Working the long shovel blade back and forth breaks up 

compacted soil and creates planting holes deep enough for large container stock (D).

A

B

C D

336
auger with a special bit has been developed for planting large container stock in rocky soils (St. 

Amour 1998). 

Expandable Stinger – Specialized planting equipment is needed for the rocky and steep slopes 

that are often found along forest roads. The original stinger was a pointed metal bar that was 

hydraulically forced into the soil to plant willow and cottonwood cuttings. The expandable 

stinger is a recently developed planting device attached to the arm of an excavator (Figure 

10.122) that creates a hole and plants the seedling all in one operation. The planting head is 

composed of two parallel steel shafts, which are hinged in the middle to open and close in a 

scissor-like manner. Each shaft is constructed to create a long hollow chamber between them 

when closed. The opening and closing of the shafts are hydraulically driven. When the shafts 

are closed, the stinger comes to a point and is pushed into the soil by the force of the excavator 

arm. A long hardwood cutting or container plant is placed into the chamber. The expandable 

stinger is maneuvered to the planting spot, where the beak is inserted into the soil. When 

the beak opens, the seedling drops to the bottom of the hole leaving, the seedling in place 

(Figure 10.122B-D).

Two expandable stinger models are currently in use. The single-shot model inserts plants one 

at a time and averages between 50 to 80 seedlings per hour. The 50-shot model contains a 

rotary magazine that can hold fi fty plants of up to three diff erent species and can double the 

planting rate of the single-shot model (Kloetzel 2004).

The advantage of this equipment is that it can reach very steep cut and fi ll slopes, sites that 

are inaccessible by other planting methods. Smaller excavators can reach 25 feet, while larger 

machines extend planting up to a 50 foot radius, which is adequate for most cut and fi ll slopes. 

This equipment can also plant in very rocky soil conditions, including rip-rap and gabions, and 

can insert plants up to 6 feet. With the typically compacted soils on roadside sites, the action 

of the beak of the expandable stinger breaks up the compaction around the planting hole. 

While soil typically falls back around the root plug after the expandable stinger has planted 

the seedling, it is still important to determine whether additional soil needs to be fi lled and 

tamped around the plant. Poor soil contact with the root system can reduce survival and 

growth during establishment.

The major drawback to the expandable stinger is the expense. Because of the high hourly rate 

of an operator and equipment, the expandable stinger must be working at full capacity at all 

times. Good planning is essential. This means that all the planting sites are laid out before the 

Roadside

Revegetation

Introduction

Initiation

Planning

Implementation 

Guides

Monitoring

& Management

Summary

Figure 10.121 – Power augers are eff ective because one trained operator determines the depth 

and spacing of the planting holes (A). Auger bits come in a variety of sizes to accommodate the 

large stocktypes favored in restoration plantings (B). 

A B

337
equipment arrives, there is a clear understanding of species mix and planting for each planting 

area, seedlings are on the site and ready for loading into the equipment, and there is enough 

personnel to keep the equipment going. In a well-planned operation, the expandable stinger can 

plant up to 200 seedlings in an hour. In addition to the hourly operating costs, the mobilization 

costs can be very high, especially if the excavator and expandable stinger must be transported 

across several states. These costs must be spread across all seedlings being planted for a true 

cost. The more seedlings that are planted by the expandable stinger at one construction site, 

the less it will cost per planted seedling. Larger planting projects (>1,500 seedlings) spread 

these costs over more seedlings and make expandable stinger projects economical.

Pot Planter – The pot planter is a modifi cation of the waterjet stinger (See Section 10.3.3, 

Installing Cuttings) that creates planting holes large enough for container plants. Like the 

waterjet stinger, it draws water from a water source (e.g., a lake, stream, water truck) and 

hydraulically creates a planting hole as the tip of the high pressure nozzle is pushed into the 

soil (Figure 10.123A). The pot planter has 3-inch vanes attached to the sides of the nozzle, which 

create holes large enough for containers up to one gallon (Figure 10.123B). The hole that is 

created by the pot planter is actually a soil slurry that is displaced when the root plug is pushed 

into it at the desired planting depth. Once the water drains from the slurry into the surrounding 

soil, the soil settles in around the root plug, assuring good soil-to-root contact.

The advantages of using a pot planter include: 1) container plugs are thoroughly moistened 

at outplanting, 2) there are fewer air pockets in the soil and better root-to-soil contact, and 

3) soil around the planting hole is moistened, allowing roots more time to move out of the plug 

and into the native soil. These advantages create the opportunity for earlier fall planting dates, 

even as early as late August to early September in some areas. The earlier the fall planting, the 

greater the chance for rooting to occur before winter sets in. This rooting will be in addition 

to the root growth that occurs the following spring and can make the diff erence in whether 

a seedling survives the fi rst growing season. Large containers can be planted quickly at a rate 

of approximately one plant per minute (Hoag 2006). The pot planter is limited by the same 

factors as the waterjet stinger, which include steep slope gradients, inaccessibility, high soil 

rock content, and poor water source availability.

Roadside

Revegetation

Introduction

Initiation

Planning

Implementation 

Guides

Monitoring 

& Management

Summary

Figure 10.122 – The expandable stinger is operated by placing a long container or hardwood 

cutting into the chamber (A). The arm of the excavator pushes the point of the stinger into the 

soil to the appropriate planting depth for the root system (B) and the beak opens, shattering the 

soil (if it is compacted) and creating a hole (C). The stinger is removed and the plant remains in 

place as soil collapses around the sides of the plug (D).

B C D

A

338
Planting into Engineered Structures – There are occasions when seedlings will be planted 

as engineered structures are being built. These structures include vegetated gabion walls, 

riprap, and retaining walls (See Inset 10.22 in Section 10.3.3). Planting must be well planned 

and integrated into the construction schedule. Since road construction often takes place in 

the summer when plants are in full growth, special handling methods and irrigation must be 

implemented during installation to assure optimum seedling establishment (Figure 10.124). 

Installing plants into riprap, for example, requires good planning and integration into 

construction activities. Drawings and a set of planting instructions are essential. Seedlings are 

partially planted in the existing soil and partially in riprap. Riprap and soil is hand placed around 

the seedling plug to assure good root–to-soil contact and that the seedlings are handled with 

care. The remainder of the riprap is placed and the seedlings are irrigated. Each vegetated 

engineered structure will require diff erent sets of instructions and drawings that are specifi c to 

the objectives and environmental conditions of the site.

Roadside

Revegetation

Introduction

Initiation

Planning

Implementation 

Guides

Monitoring

& Management

Summary

Figure 10.123 – The pot planter creates a planting hole by injecting high pressure water into 

the soil (A). Once the soil is liquefi ed, the container is pushed into the soil to the appropriate 

depth (B).

A B

Figure 10.124 – Engineered structures 

of gabions and riprap require tall nursery 

stock and special installation techniques. 

When properly done, however, plants 

survive and grow well and greatly 

increase the visual appearance of 

the structure. 

339
10.3.4.4 Assess Plant Inventories

Depending on the size and scope of the project, there may be many combinations of species, 

seedlots, and stocktypes being grown at one or more nurseries. Seedling inventories from all 

nurseries where your stock is being grown must be consolidated into one list. Each nursery will 

supply a list of the quantity of seedlings in each seedlot that meet the contract specifi cations. 

Do not be surprised if this list does not exactly meet your original order. It is rare that the 

original seedling order ever gets fi lled exactly as requested. Some seedlots grow well, while 

others grow poorly, and this is refl ected in the seedling inventory. You will fi nd there are more 

seedlings in one seedlot and less in another. 

Plant inventories do not always give the full story about seedlots. Prior to putting together 

a planting plan, a visit to the nurseries will give a full picture of the status of each seedlot. 

Stressed seedlings, poor roots, root-bound seedlings, disease, and other problems can only be 

realized by visiting the nursery months before plants are received. The visit to the nursery is 

not always a negative fact fi nding mission. It should be approached as a problem-solving trip. 

For example, an inventory might indicate that certain seedlots do not meet size specifi cations. 

A closer review at the nursery may show that many of the seedlings that do not meet size 

specifi cations would be suitable in certain planting areas. If inventories are low, discussions 

with the nursery manager might bring up the possibilities of substituting surplus seedlots from 

other clients for the downfall in your inventory.

10.3.4.5 Match Inventories to Planting Area

At this point, the information developed during the location of planting units, including 

seedling density, species, and stocktype, must be reevaluated in light of the newest seedling 

inventory. In other words, the seedlings from the inventory must now be divided between 

planting areas in a manner that still meets the project objectives. 

Using the spreadsheet in Figure 10.125 is a simple way to reconcile the diff erences between the 

plants needed at each planting area and the plant inventory. In this example, three planting 

areas are defi ned (A1, A2, and B). For each planting area the number of plants of each species/

stocktype are listed. The planned needs are summarized in Line A. When the seedling 

inventory (Line B) is received, it is 

discovered that there will not be 

enough ponderosa pine (PIPO) or 

quaking aspen (POTR5) to meet the 

planned needs. The defi cits are circled 

in Line C. In this example seedlings 

can either be obtained from other 

sources, or the plant needs can be 

adjusted downward. In this example, 

the PIPO and POTR5 were adjusted 

downward because no substitute 

trees could be found to make up 

the diff erence. AMAL2 (Saskatoon 

serviceberry) was adjusted upward as 

a partial substitution for the shortfall 

of tree seedlings. Planting spacing was 

recalculated from Figure 10.117 with a 

resulting increase of approximately 

1 ft for both PIPO and POTR5. The 

extra PUTR2 (antelope bitterbrush) 

and PREM (bitter cherry) were not 

planted (Line F), but surplused to a 

local landowner. Many more rows and 

columns can be added to this spread 

sheet to accommodate more species 

and planting areas. Roadside

Revegetation

Introduction

Initiation

Planning

Implementation 

Guides

Monitoring 

& Management

Summary

Figure 10.125 – Spreadsheets are a handy way 

to keep track of nursery orders and adjust plant 

inventories to planting needs. 

Planting Areas

Planned Seedling Needs

Species & Stocktype

Planned Needs

Seedling Inventory

Difference

A

B

C

PIPO POTR5 AMAL2 PUTR2 PREM

A1

A2

B

2 Gal 1T18 1T12 1STP 1STP

425 238 117

75

500

400

-100

25 35

152

200

48

100

125

25

50

75

25

100

275

538

435

-103

50

Planting Areas

Species & Stocktype

Adjusted Needs

Seedling Inventory

Difference

D

E

F

PIPO POTR5 AMAL2 PUTR2 PREM

A1

A2

B

1 Gal 1T18 1T12 STP STP

350 200 155

50

400

400

0

10 45

200

200

0

100

125

25

50

75

25

100

225

435

435

0

50

Adjusted Seedling Needs

340
10.3.4.6 Transport Plants

The delivery of seedlings to the 

planting site is not generally the 

responsibility of the nursery. It can be 

an item in the seedling production 

contract, a separate transportation 

contract, or you can transport them 

yourself. Whichever way you decide, 

remember that seedlings can be 

easily damaged during transportation 

by poor handling, hot temperatures, 

or drying conditions. Plants that have 

been packed in bags or boxes are 

protected from drying conditions and 

can be transported in most vehicles. 

If containers are transported in open 

pickups, they should be covered with 

a space blanket or special tarps to 

moderate temperatures and minimize 

the potential for desiccation (Figure 

10.126). Specially-constructed Mylar® 

tarps can be purchased from forestry 

or restoration supply companies. 

Plants that have been kept in freezer 

storage should be thawed prior to 

transportation and planting. While 

small container stock has been shown 

to have satisfactory survival when 

planted frozen, there is no indication 

that large stock will perform the 

same. Once frozen seedlings have been thawed or cooler-stored seedlings have been allowed 

to warm, they should be planted immediately. Seedling viability will decrease if they are placed 

back into cold storage for more than a few days.

Plants that have not been packed in storage containers must be transported in enclosed 

units. Transporting plants in open vehicles, such as pickups, exposes foliage to strong, drying 

winds which can unduly stress the plants. Large container plants typically stand 2 to 4 feet 

tall (including the container) and require transportation with enough space to accommodate 

the size.

10.3.4.7 Develop Planting Contract 

The following discussion outlines some of the basic components that should be addressed in 

a planting contract.

Location – A map of the planting areas should be included in the contract.

Planting Quantities – The quantity of species, by stocktype, must be presented for each 

planting area.

Planting Method – There might be several planting methods which should be indicated for 

each stocktype and planting area.

Plant Spacing Requirements – For each planting area, describe or defi ne the plant spacing 

at which each species will be planted. Calculations to determine the proper spacing between 

plants was presented in Figures 10.117. Approximate distance between plants can be 

determined graphically by knowing the target plants per acre, and, in reverse, the plants per 

acre can be determined by knowing the target spacing between plants (Figure 10.127). For 

example, if the plan calls for a density of 600 seedlings to be planted per acre, the spacing 

between plants would be around 8.5 feet (Figure 10.127A). If the plan calls 600 seedlings to be 

planted in planting pockets of three plants per pocket, there would be 200 planting pockets 

spaced approximately 15 feet apart (Figure 10.127B). In another example, if you want to know 

the number of seedlings to order for a given area with a target spacing of 6 feet, the number of 

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Figure 10.126 – During transportation and onsite storage, nursery stock should be covered with 

special refl ective tarps (A) which have been proven 

to reduce temperature buildup (B).

Dark-Green Canvas

Bagged Seedlings - Sun

Temperature ( ̊F)

Time of Day

110

100

90

80

70

60

50

40

30

9 10 11 12 1 2 3 4

White Cloth Sheet

Air Temperature - Sun

Mylar® Silver Surface

Mylar® White Surface

Bagged Seedlings - Shade

A

B

341
plants required would be just under 

1,100 seedlings (Figure 10.127C).

These spacing requirements are an 

average. Depending on the plantability 

of a site, the specifi ed average spacing 

may vary up to 25% in any direction 

to fi nd a suitable planting spot. Where 

an unplantable spot is encountered, 

the planter will plant in the closest 

plantable spot. Whenever possible, 

plants should be installed next to 

stumps, logs, or other obstacles that 

provide partial protection from sun, 

wind, and animals. If planting islands 

are designed into the planting areas, 

each island should be marked within 

the planting area by the contract 

inspector and the species mix should 

be stated in the contract. 

Handling Care – Plants must be handled with care to prevent damage to roots and foliage. 

Seedlings must not be thrown, dropped, hit, or otherwise mechanically impacted. Extracting 

the root plug from the container must be done gently, avoiding excessive force when pulling 

the seedling from the container. Seedlings should not be removed from containers until the 

hole is excavated. The container is then removed, and the seedling is quickly planted. Excessive 

exposure of the root system to the air will decrease seedling survival and growth (Greaves and 

Hermann 1978).

Root Pruning – The bottoms of some containers are poorly designed, causing roots to circle or 

build up at the bottom of the pot (Figure 10.128A). These damaged roots must be cut prior to 

planting to prevent potential root strangling, especially for tap-rooted woody species (Figure 

10.128B). Root pruning is best accomplished at the nursery, but must be stated in the growing 

contract to cover the added expense. Pruning in the fi eld is not recommended because of 

the increased root exposure. However, it may be necessary when nursery stock arrives with 

constricted roots.

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Figure 10.128 – Roots will circle and accumulate at the bottom of some container types (A), 

especially if the stock has been held too long. Pruning these roots at planting will ensure that 

new roots will promptly grow out into the surrounding soil (B).

A B

Figure 10.127 – Approximate distance between 

plants can be determined from this graph by 

knowing the target plants per acre, and, in reverse, 

the plants per acre can be determined by knowing 

the target spacing between plants.

24

22

20

18

16

15

12

10

8

6

4

2

0

100 200 400 600 800 1,000

Spacing Between Plants

Plants per Acre

1,200 1,400 1,600 1,800 2,000

C

A

B

342
Container Moisture – Root plugs that are dry must be thoroughly moistened prior to planting. 

Irrigating seedlings at the nursery several days before shipping and again on the day of shipping 

assures that root plugs are completely wet. These instructions must be conveyed to the nursery 

manager prior to picking up the seedlings. Provisions should be in the contract that addresses 

the need for wetting root systems should they be dry at the time of planting. Wetting root 

plugs can be accomplished by dipping seedling containers into a large water container, such as 

a cattle trough or trash can, prior to planting. Planting seedlings using the pot planter assures 

that the root plugs are wet at planting.

Temporary Storage – If container plants cannot be planted in one day, they can be stored 

in the fi eld in a well-sheltered area protected from the sun and animals. Refl ective tarps are 

recommended to keep plants cool and moist during on-site storage (Figure 10.126). If container 

plants are left out for several days, the root plug should not be allowed dry out. If they do lose 

moisture, the containers must be irrigated prior to planting. Plants that have been extracted 

and placed in storage boxes or bags should not be left on–site, but returned to a local cooler 

for storage.

Planting – Prior to preparing the planting hole, the planters must clear the surface of the 

planting spot of all limbs, logs, snow, duff , litter, rocks, and other loose debris. If sod, crowns of 

living plants, and roots are present, they must be scalped down to moist mineral soils. Clearing 

and scalping dimensions must be stated in the contract. Planting holes shall be located 

near the center of the prepared planting spot and they should be dug vertically rather than 

perpendicular to the ground surface. The planting hole should be three to four inches deeper 

than the total length of the root system or root plug, and wide enough to fully accommodate 

the width of the root system. Seedlings should be placed in the hole so that the cotyledon scar 

(the bump or constricted area on the seedling stem that is the transition from the root system 

to the stem) is one inch below the ground line. Species that can be rooted from cuttings can 

be planted deeper, since portions of the stem will root when buried. The root plugs should not 

be forced into the planting hole, distorted, or broken during planting. After placing the plant 

in the hole, excavated soil is placed fi rmly around the root system so there is no loose soil or 

air pockets around the root plug. The root system must not be damaged during this operation. 

A small circular water-holding basin can be created around each seedling after planting to 

capture water or store irrigation water. 

10.3.4.8 Administer Contract

The planting contract inspector must 1) schedule the shipment of seedlings from the nursery, 

2) be certain that root plugs are moist and ready for planting, 3) have the right quantities 

of plants at each planting area, and 4) inspect the contract. In addition, if there are special 

planting patterns designed for the planting area, these may need to be marked on the site prior 

to planting. 

The planting inspector must determine if the conditions are favorable for planting. Seedlings 

should not be planted into dry soil unless the planting spot is irrigated immediately after 

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Figure 10.129 – Monitoring the survival 

and growth of nursery stock for several 

years after planting provides valuable 

information for future projects.

343
planting or the pot planter method is being used. Under certain circumstances, high moisture 

soils follow geomorphic features, such as creek or river terraces where high ground water 

brings moisture to the soil surface. These sites should be identifi ed on the ground at the time 

of planting. 

10.3.4.9 Monitor Planting Success

Valuable information can be gained by monitoring nursery stock for several years after planting. 

The fi rst few months are critical because nursery plants that die immediately after outplanting 

indicate a problem with nursery stock quality. Plants that survive initially, but gradually lose 

vigor, indicate poor planting or drought conditions. Therefore, plots must be monitored during 

and at the end of the fi rst year for initial survival. Subsequent checks after 3 years will give 

a good indication of plant growth potential (Figure 10.129). This performance information is 

then used to give valuable feedback to the nursery manager, who can fi ne-tune the target 

specifi cations for the next crop.

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10.4 POST INSTALLATION CARE OF PLANT MATERIALS

The fi rst year after plant materials are installed on a project site is typically the most critical 

period in a revegetation project because this is when plants become established. Applying the 

appropriate mitigation measures to improve the site and soil conditions prior to installation of 

plant materials greatly increases the chances of plant establishment. Sometimes even these 

measures are not enough to overcome limiting site factors. The implementation guides in this 

section cover several post installation measures that can be done to increase the potential of 

plant establishment.

Establishing plants from nursery stock is often limited by animal browsing. Section 10.4.2, 

Animal Protection, covers the methods available for protecting plants from diff erent forms of 

animal damage. On hot, dry sites, plants need to be shaded from mid to late afternoon solar 

radiation. The application of shade cards, Section 10.4.3, is one method for protecting young 

plants from heat stresses. Moderating the climate around plants from extreme temperatures 

and high evapotranspiration rates is sometimes accomplished through the use of tree shelters. 

Section 10.4.4, Tree Shelters, outlines when these structures are used, product types, and how 

they are applied. Some projects require supplemental irrigation for establishing seedlings 

on extremely dry sites. Section 10.4.5, Irrigation, discusses two types of irrigation used in 

revegetation projects – deep pot irrigation and drip irrigation.

10.4.1 INTRODUCTION

The fi rst several years after the installation of seedlings are critical for the survival of healthy 

nursery plants. In the western United States, nursery plants die because of animal damage, 

high surface temperatures, high evapotranspiration rates, lack of soil moisture, and vegetative 

competition. In this section, we will discuss certain steps to reduce these impacts. Where animal 

browsing is high, fencing, netting, and animal repellants are important to consider (See Section 

10.4.2). For high surface soil temperatures shade cards can be used to protect seedlings (See 

Section 10.4.3). Reducing evapotranspiration rates is achieved using tree shelters (See Section 

10.4.4) and shade cards. Some high visibility projects require fast growth rates and low risk in 

plant establishment, in which case irrigation can be considered (See Section 10.4.5). Additional 

measures that benefi t seedling survival are covered in other sections. These include applying 

mulch around seedlings to conserve soil moisture and reduce vegetative competition (See 

Section 10.1.3), spot fertilizing (See Section 10.1.1), and applying mycorrhizal inoculum (See 

Section 10.1.7). 

10.4.2 ANIMAL PROTECTION

Planted seedlings can be damaged by a variety of animals, including cattle, deer, elk, gophers, 

and voles. While some damage by animals can be expected, excessive damage should be 

prevented. There are a variety of methods to protect seedlings which include rigid and nonrigid netting, fencing, and animal repellents. 

10.4.2.1. Netting

A common practice for protecting seedlings from browsing animals is to install a plastic netting 

over each seedling. The netting acts as a barrier to foraging of foliage, stems, and even root 

systems, without impeding plant growth. It has been used to protect seedlings from deer, elk, 

gophers, and other ground burrowing animals.

There are two general types of netting – rigid and non-rigid. Non-rigid netting is a soft, fi nemesh plastic material. When installed on a seedling, it fi ts snuggly around the foliage like a sock. 

The rigid netting (Figure 10.130) has larger mesh openings and holds its form when installed. 

Rigid netting, while typically more expensive, is usually preferred over non-rigid because it is 

easier to install and seedling growth inside the netting is less restricted. 

Netting must be installed as soon after planting as possible to ensure immediate protection. 

If installation occurs after bud break, care must be taken not to break or damage the terminal 

leaders or buds. Rigid netting is held in place with one or two bamboo stakes woven through 

the netting at three places and driven into the soil at a minimum depth of 8 inches. For deer 

and elk protection, netting is placed so the height of the netting is several inches or more 

above the terminal bud. Non-rigid netting is simply placed over the foliage like a sock and 

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not secured with stakes. Rigid netting can off er some protection from gopher damage if the 

netting is installed more than several inches below the surface of the soil (Figure 10.130).

The eff ectiveness of the netting decreases as the terminal leader grows out of the rigid netting 

and become susceptible to browsing. At this point, the netting can be repositioned upward to 

protect the terminal leader, which requires annual maintenance. At some point, netting must 

be removed entirely to avoid restricting seedling growth and ultimately killing the seedling. 

Some netting has been manufactured with photodegradable material which will break down 

within several years, eliminating the need for removal. Nevertheless, sites that have had any 

type of plastic netting installed on seedlings should be visited several years after planting to 

determine whether the plastic netting is decomposing or needs to be removed. 

10.4.2 2. Fencing 

Fencing is often used to protect planted or seeded areas from wild ungulate and livestock 

grazing or trampling. Each group of animals requires diff erent fencing specifi cations. Fence 

height for wild ungulates require 8 to 12 ft (Helgerson and others 1992) while fence height for 

livestock is 4 to 5 ft. Fences must be installed prior to seeding or planting to ensure optimal 

plant establishment. 

Fencing entire planting or seeding areas is expensive to install and maintain. Maintenance must 

be given high priority because one break or opening in the fence will place the entire project at 

risk. It has been recommended that fences be monitored and maintained at least once a week 

and up to three times per week during peak browse season (Greaves and others 1978). 

An alternative to fencing entire planting areas is to fence strategically located areas, such as 

planting islands. Fenced areas, called exclosures, range in diameter from 6 to 15 ft and are 

typically constructed with a 14 gauge, galvanized welded wire mesh (2- by 4-inch openings). 

Fence heights can be reduced around small diameter exclosures because wild ungulates 

are less likely to jump into small areas (Gobar 2006). Fence heights as low as 5 ft have been 

installed with good results (Riley 1999). In this strategy, the smaller size and greater number 

of exclosures reduces the risk of a failed project. After seedlings have grown high enough to 

withstand grazing and browsing pressures, small enclosures should be removed.

10.4.2.3. Animal Repellent

Browsing by deer and elk can be temporarily controlled by applying animal repellents to the 

foliage of seedlings. There are a variety of repellents on the market with varying degrees of 

eff ectiveness. Trent and others (2001) tested 20 products for eff ectiveness in reducing deer 

browse on western redcedar (Thuja plicata) seedlings and found that products emitting 

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Figure 10.130 – Rigid netting can 

protect seedlings from deer, elk, and 

gopher damage. The netting in this 

picture was installed 3 inches below 

the ground line to protect the seedling 

from gophers while the foliage and 

terminal leader is protected from deer 

and elk browsing.

346
sulfurous odors were the most eff ective. These products contain active ingredients such as 

“putrescent whole egg solids” or “meat meal.” Less eff ective products were those causing pain 

or irritation, containing active ingredients such as capsaicin, garlic, d-limonene, and thiram. Of 

the products tested, the least eff ective repellents protected seedlings for a few weeks, while 

the most eff ective protected seedlings for up to three months. Since seedlings are generally 

more palatable after winter dormancy, deer repellents should be applied just before bud break 

(Helgerson and others 1992) and at several month intervals during the active growing period as 

needed. Animal repellents in a hydrophilic powder formulation are reported to adhere better 

and last longer in climates with high rainfall than liquid forms (Helgerson and others 1992).

10.4.3 SHADE CARDS

Since high soil surface temperatures can limit seedling survival and growth, it is important that 

the stem of the seedling (where heat buildup occurs and causes the most damage) is shaded 

from the sun (Childs and Flint 1987). Seedlings can be planted next to obstructions, such as 

logs, to utilize the shade these structures provide. Unless the placement of obstacles is planned 

into the project, construction sites will usually be free of material large enough to cast shadows. 

An alternative, but less eff ective, method of creating shade is using shade cards. Shade cards 

are small, easy-to-install structures that shade the lower portions of the seedling from high 

surface soil temperatures (Figure 10.131). Tesch and Helms (1992) reviewed numerous studies 

that evaluated the eff ects of shade cards on planted seedlings and found that, while the use 

of shade cards can signifi cantly improve seedling survival, they should only be considered on 

sites where several revegetation conditions are suboptimal, including south-facing aspects, 

sites with high winds, or when planting small, poor quality stock.

To be eff ective, shade cards should be installed in the spring after planting and before hot 

weather sets in. It is important to know where the shadow of the installed shade card will be 

cast in order to know where to place the card. The shadow must cast shade on the stem and 

lower portions of the seedling to protect these areas from high surface temperatures during 

the hottest portion of the day (Childs and Flint 1987). The length of the shadow is dependent 

on the longitude, date, time of day, slope angle, and height of the shade card. Improper 

installation of shade cards is a common mistake which typically occurs when cards are placed 

on the wrong side of the seedling. Card installers must be aware of the cardinal directions at 

all times during the day, which can be diffi cult on cloudy days. For this reason, contractors 

and inspectors should use a compass when installing cards and inspecting contracts. Another 

common mistake is not placing the shade card close enough to shade the base of the seedling 

during the hottest times of day. 

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Figure 10.131 – Shade cards are placed 

on the south side of the seedling so the 

shadow cast by the shelter protects 

the lower portion of the seedling. This 

photo was taken two years after shade 

card placement.

347
Shade cards are also used to protect seedlings from strong, drying winds that create high 

moisture stress for establishing seedlings. Typically, shade cards are placed on the windward 

side of the seedling to defl ect the wind. It is important to know the direction of the strongest 

or hottest wind in order to properly install the shade cards. For example, on a site with strong, 

drying winds coming up-valley in the afternoon, two shade cards would be installed at 90° 

angle to each other on the down-valley side to enclose the seedling.

Shade cards are made from shingles, cardboard, tarpaper, and polypropylene mesh. Selecting 

the appropriate shade card for your site should be based on how easy the shade card is to 

install, the weight, dimensions, life span, and costs. The drawbacks to the use of shade cards are 

the visual impact on the site and the fact that they must be removed after several years.

10.4.4 TREE SHELTERS

Tree shelters are translucent plastic tubes that are placed around seedlings after planting (Figure 

10.132). They benefi t seedling establishment by creating a favorable growing environment 

while shielding the seedling against animal damage. Tree shelters enhance plant growth by 

creating a microclimate similar to a mini-greenhouse, which has lower light intensities, higher 

temperatures, and higher relative humidities (Applegate and Bragg 1989; Jacobs and Steinbeck 

2001). On high elevation sites, tree shelters increase above-ground temperatures and extend 

the growing season (Jacobs and Steinbeck 2001). Seedling survival and growth is enhanced 

by tree shelters on some sites because increased condensation on the inner shelter walls 

during the evening, drips into the soil and increases soil moisture (Bergez and Cupraz 1997). On 

windy sites, tree shelters protect seedlings from wind damage and blowing sands (Bainbridge 

1994). In addition, tree shelters protect seedlings from large game, gophers, rabbits, voles, and 

grasshoppers (Tuley 1985; McCreary and Tecklin 1997; Jacobs and Steinbeck 2001).

Where to Use: Tree shelters should be considered for sites where the potential for animal 

damage is extreme and seedling survival and rapid seedling growth are essential. These sites 

include but are not limited to sites with the following characteristics:

 · Gopher or vole damage,

 · High elevation,

 · High winds,

 · Hot and dry,

 · High solar intensity,

 · Low water-holding capacity soils, and

 · “One-shot” planting.

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Figure 10.132 – Corrugated plastic 

tree shelters create a microclimate 

around seedlings to enhance moisture 

and temperatures for seedling growth. 

In addition, they protect plants from 

animal browsing.

348
Drawbacks: Tree shelters are not intended for all species or site conditions. Several studies 

have shown that, under certain climates, seedlings grown in tree shelters are more susceptible 

to low temperature extremes than those grown in the open (Svihra and others 1993; Kjelgren 

and others 1997). These conditions occur in the late winter and early spring on some sites when 

warmer daily temperatures in tree shelters induce earlier bud break and stem dehardening, 

leaving seedlings more susceptible to cold temperatures. Air temperatures can also be colder 

at night in tree shelters on some sites because tree shelters can potentially trap cold air near 

the ground surface (Swistock and others 1999). On the opposite extreme, extremely high 

temperatures in the summer can be reached inside the shelters during mid-day, which might 

be detrimental to seedling growth. For these reasons, installing tree shelters should be done 

with some understanding of the eff ects that the shelters will have on each species to be planted 

and the climate of the site. Small trials, prior to installation, can point out potential problems.

In visually sensitive areas, tree shelters do not blend well with natural backgrounds. Depending 

on the species and the site, tree shelters might have to remain around plants for up to fi ve 

years. In addition, long range planning for shelter removal is critical; without removal, the stem 

of the plant can be restricted. 

Installation: Installing tree shelters may be done during or immediately after planting to protect 

seedlings from animal damage. Tree shelters are usually delivered in stacks of plastic sheets. 

They are assembled on site into cylinders that are placed over the seedling and held upright 

with a stake (Figure 10.132). The stake is driven into the soil so that the bottom of each cylinder 

is in direct contact with the soil surface. If burrowing animals are a problem, shelters can be 

installed several inches below the soil surface. This is an eff ective control of gophers and voles 

(McCreary and Tecklin 1997; Jacobs and Steinbeck 2001). Netting is sometimes placed over the 

opening of the shelter to prevent birds and lizards from becoming trapped (Bainbridge 1994). 

Rigid tubing can be placed over the top of the tree shelter to protect the emerging foliage from 

deer and elk browse (Figure 10.133). Tall tree shelters will require very strong stakes anchored 

fi rmly in the soil to withstand strong winds. As the shelters are installed, care must be taken 

to avoid skinned bark, damaged buds, or broken leaders. Where moisture is a limiting factor, 

weeding the vegetation from around the shelters is essential. Seedlings competing with weeds 

are unlikely to take advantage of the water saved by a tree shelter (Bainbridge 1994; McCreary 

and Tecklin 1997).

Maintenance and Removal: Installed properly, tree shelters require little maintenance. 

Nevertheless, sites where tree shelters are installed should be inspected annually to assess 

seedling conditions in the tree shelter and determine if any maintenance is needed. Since 

yellow jackets and other animals create homes inside tree shelters, it is wise to be cautious 

when conducting inspections. 

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Figure 10.133 – Rigid tubing can 

be installed over the top of the tree 

shelter to protect seedlings from larger 

browsing animals.

349
Tree shelters create growing conditions that favor seedling height growth over stem diameter 

growth (Figure 10.134). Since tree shelters physically support the seedlings while they are 

growing, the seedling directs more of its energy into growing up to the light and less into the 

stem. Tree shelters must not be removed until a portion of the seedling crown has grown out of 

the shelter. If the tree shelter is removed while it is still growing inside the shelter, the seedling 

will not be capable of supporting itself. Once the seedling has emerged from the shelter, stem 

diameters will continue to increase as the foliage acclimates. 

Available Products: Tree shelters are available in a variety of shapes, sizes, colors, and styles 

from companies that specialize in reforestation, restoration products, or grape growing. 

Color. Color and translucency of the plastic are important characteristics for selecting a tree 

shelter. Brown-colored tree shelters greatly reduce solar radiation and, in one study on a 

high elevation site, was shown to drastically decrease seedling survival of Engelmann spruce 

(Picea engelmannii) (Jacobs and Steinbeck 2001). But on hot, dry sites, reduced radiation might 

benefi t seedlings. Oak seedlings (Quercus spp).planted in a semi-arid environment actually 

performed best in short, brown-colored shelters because of reduced daily temperatures (Bellot 

and others 2002). 

Lighter colored tree shelters allow greater solar radiation to reach the seedling, but can also 

heat up when they are exposed to direct sunlight. Highly translucent tree shelters should be 

considered where light is limiting. On the other hand, low translucent shelters might be more 

appropriate for sites where solar radiation and mid-day temperatures are high in order to 

reduce the potential for overheating. 

Material. Tree shelters are made from translucent plastic for light transmission built with 

diff erent degrees of sturdiness. Corrugated tree shelters are the sturdiest and are used on 

sites with strong winds. Corrugated materials are also used in the taller tree shelters for added 

support (Figure 10.132), while thin plastic can be used in shorter shelters. Tree shelters are 

typically designed to degrade in fi ve years, but in many cases they do not. Many shelters can 

therefore be reused, which will reduce project costs.

Ventilation. Without ventilation, tree shelters will build up heat on warm days, especially if 

they are in direct solar radiation. Maximum daily summer temperature in shelters can be 8 to 

16 °C (15 to 30 °F) higher than ambient air temperatures (Steinfeld 2005). Extreme temperatures 

can be reached on days where ambient air temperatures exceed 38 °C (100 °F). For these sites, 

shelters with some form of ventilation, such as holes, should be used. Ventilated tree shelters 

have been shown to reduce maximum daily shelter temperatures by 3 °C (5 °F) (Swistock and 

others 1999). Where ventilation is needed, taller shelters will require more ventilation than 

shorter shelters. 

A ventilated tree shelter may restrict CO2 in the area around the seedlings, which would be a 

further consideration for ventilation. Some studies have shown that CO2 is very low in shelters 

(Dupraz and Bergez 1997). However, other studies that have shown higher levels of CO2 within 

shelters than outside (Frearson and Weiss 1987).

Size. Selecting the size of the shelter should be based on the anticipated growth rates of the 

species planted and the anticipated animal damage. Shelter heights range from 1 to 9 ft, and 

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Figure 10.134 – A study 

conducted with Australian 

redcedar (Toona australis) on 

a warm, moist site in North 

Queensland showed that, as taller 

tree shelters are used, fi rst year 

shoot growth increases. Stem 

diameters, however, do not change 

(Applegate and Bragg 1989).

Height 3.0

2.5

2.0

1.5

1.0 4

6

8

10

12

2

0

0.5

0 1 23 4

Stem Diameter

Height of Shelter (m)

First Year Seedling Height (m)

First Year Stem Diameter (cm)

350
diameters up to 6 inches. To obtain the greatest benefi t from tree shelters, the shelter height 

should not exceed the maximum seedling growth in the fi rst year. Fast-growing species should 

have tall shelters; shorter shelters should be used for slow-growing species. Ideally, the shelter 

height should be greater than the browsing level of the foraging animal. For instance, tree 

shelter heights in deer browse areas should be at least 4 ft tall so that new seedling growth 

from the top of the tube is not severely browsed back. Extending the protection of the tree 

shelter can be done by using a rigid netting placed over the top of the shelter. Large shelters 

can be cut into any height or diameter needed for the project. Very small shelters (less than 

6 inches tall) can be used around germinating seeds to protect them from small animals and 

create a micro-climate for germination (Figure 10.135).

Costs: Tree shelters can be an expensive addition to the revegetation project. The high costs 

to purchase, assemble, install, maintain, and remove shelters should be considered against the 

benefi t of increase survival and growth. On projects where smaller, less expensive seedlings are 

being planted, the cost savings from not planting larger stock can off set the installation of tree 

shelters. Assuming that tree shelters increase seedling survival, fewer seedlings would need 

to be planted, and these savings could off set the costs of installing tree shelters. Where quick 

establishment of vegetation is the objective, the use of tree shelters should be considered.

10.4.5 IRRIGATION

There is a wide range of irrigation methods and techniques available to the revegetation 

specialist, ranging from simple to elaborate, and modestly priced to costly. Since irrigation is 

often a very expensive revegetation strategy for most projects, the decision to irrigate, and 

subsequently the selection and design, must be integrated into the objectives of the road 

project during the planning stages. The most common reason for irrigating in the western 

United States is to aid in seedling survival during the fi rst several growing seasons. Those sites 

that have low soil water-holding capacities, high evapotranspiration rates, or low summer 

rainfall meet these criteria. Irrigation is also used when the project objectives call for a quick 

establishment of vegetation for visual screening, erosion control, or slope stabilization. 

Wildland irrigation is almost always a temporary measure, spanning a maximum of three years. 

Therefore, elaborate or expensive irrigation systems are not often the best choice for these 

situations. Low-tech systems, requiring minimal maintenance, tend to be more appropriate for 

wildland restoration. 

The challenge in wildland irrigation is the timing and placement of water in the soil. An 

irrigation system that delivers water when the plant is less likely to need it is wasteful and can 

be detrimental to the seedling. A system or schedule that applies water when the plant requires 

it for survival or growth is most cost eff ective and benefi cial for seedling survival and growth. 

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Figure 10.135 – Small tree shelters can 

be placed around germinating seeds to 

enhance germination and early seedling 

establishment, as shown in this picture 

of an establishing California black oak 

(Quercus kelloggii) seedling in a tree 

shelter made out of x-ray fi lm.

351
Developing irrigation schedules based on plant needs is an essential part of using irrigation for 

establishing plants, and those needs change based on the species being established, nursery 

stocktype, soils, and climate.

Placing the water in the soil profi le where it can be directly accessed by much of the root system 

is critical for effi cient use of an irrigation system. Some irrigation systems moisten more of the 

soil profi le than will be accessible by the establishing root system, and water is consequently 

wasted. Other ineff ective systems barely wet the soil surface, leaving the applicator satisfi ed, 

but the roots without water. The objective of an effi cient and eff ective irrigation system in 

wildland settings is to deliver only the amount of water needed, when and where it is needed 

for seedling survival and growth.

Tree and shrub seedlings survive by growing roots down into the soil profi le, accessing moisture 

at deeper portions of the soil profi le than annual grasses and forbs. Deep placement of water 

for these species is far more important than surface soil moisture. Yet many irrigation systems, 

such as drip, basin, and overhead sprinklers, deliver water through the surface, wetting soil 

where it is not needed, and encouraging weeds and other competitive plants to establish and 

thrive. Furthermore, surface irrigation does not always assure moisture will be evenly delivered 

to the deeper portions of the soil where the roots of trees and shrubs are growing. Soil structure 

and texture aff ect the wetting-front patterns of surface-applied irrigation water. If the soil is 

compacted, the amount of water that 

is delivered to the lower rooting zone 

can be reduced. A better method 

of water delivery to the root zone 

of trees and shrubs is to bypass the 

surface of the soil completely. 

10.4.5.1 Deep Pot Irrigation

There are several irrigation methods 

developed for arid land revegetation 

that bypass the soil surface and deliver 

water directly to the root zone. These 

systems include deep pot, porous 

hose, and wick irrigation methods 

(Bainbridge 2006a). Because these 

systems deliver water directly to the 

soil profi le where roots are actively 

growing, far less water is required. 

Deep pot irrigation (Figure 10.136) 

appears to be the most eff ective and 

practical method for irrigating planted 

seedlings in arid environments 

(Bainbridge 2006b). This system has 

been found to be three times more 

eff ective at increasing seedling 

survival than surface irrigation using 

the same amount of water (Bainbridge 

and others 2001).

Deep pot irrigation delivers water 

to the root system through a pipe 

positioned next to the seedling 

(Figure 10.136). The pipe is either 

fi lled periodically by hand or through 

an installed drip irrigation system. 

The soil is moistened as water drains 

through both the bottom of the PVC 

pipe and the holes drilled in the sides. 

The amount of water delivered to the 

soil depends on the size of the pipe 

and how much water is applied. Deep 

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Figure 10.136 – Deep pot irrigation uses an openended PVC pipe placed next to a planted seedling. 

Small holes (1 mm) are drilled 2 to 3 inches down 

the pipe and positioned toward the root system. 

A screen is placed over the top of the pipe to keep 

animals out. The size of the pipe and placement 

is designed to deliver the appropriate amount of 

water to actively growing roots (modifi ed after 

Bainbridge 2006b).

PVC pipe

Wetting

front

Screen

352
pot irrigation pipes are typically made from PVC pipes, though most pipe or tubing material 

can be used. Pipe diameters range from 0.5 to 3 inches. Pipe lengths range from 8 to 18 inches, 

depending on the stocktype and water volume to be delivered. A seedling with a short root plug 

will require a shorter pipe, whereas a longer root plug will require a longer pipe. The bottom of 

the pipe should be positioned no deeper than the length of the root plug so the wetting front 

moves around the bottom and lower portions of the plug where it can be accessed by new, 

advancing roots. The top of the pipe is screened to prevent animal entry and is placed several 

inches above the level of the soil.

The diameter of the pipe will determine the quantity of water that can be delivered at any one 

irrigation (Figure 10.137). Given the same pipe lengths, a 2 inch diameter pipe holds 4 times 

the amount of water as a 1 inch pipe, and a 3 inch diameter pipe holds 8 times the amount of 

water. Since fi lling pipes is expensive, determining the proper diameter is important. Oversized 

pipes will deliver a wetting front that extends beyond where it can be accessed by the root 

system, and water will be wasted. Pipes that are too small will not fully wet the area around 

the advancing rooting zone, requiring more frequent irrigations. Pipe size and irrigation 

frequencies depend on:

Soil Type – Sandy or rocky soils have low water-holding capacities, causing wetting fronts to 

travel deeper and in a narrower band. Less water but more frequent irrigations are needed in 

these soils. Pipes must be placed closer to the root plug to ensure the wetting front reaches the 

root system. Finer textured soils, such as loams and clays, have a higher water-holding capacity 

and wider wetting fronts. More water can be applied in these soil types and at less frequent 

intervals than sandy soils.

Stocktype – Large stocktypes have greater root volumes and greater above-ground vegetation 

to support than smaller stocktypes, and therefore require more irrigation water. However, 

smaller stocktypes might require more frequent irrigation.

Seedling Quality – Healthy seedlings grow new roots quickly and can access deeper soil 

moisture. Poor quality seedlings are slow to initiate roots and therefore must be irrigated 

more frequently.

Competing Vegetation – Where undesirable vegetation is growing near planted seedlings, soil 

moisture is depleted sooner, requiring more frequent irrigations than if seedlings were free 

from competing vegetation.

Species – Every species has unique rooting patterns, growth rates, and water needs. Those 

that grow roots quickly and have a higher rate of water withdrawal require larger, deeper 

pipes and more frequent irrigations. These species include many of the fast growing riparian 

species such as cottonwoods, willows, and maples. For more information, contact the nursery 

manager growing the species of interest. They are very familiar with root growth and water 

needs by species.

The volume of the pipes and frequency of irrigations will determine the type of water delivery 

system to use. Sites that need frequent irrigations and high volumes of water per plant might 

require water delivery through a drip system (See Section 10.4.5.2). For most projects, however, 

pipes can be economically watered by hand using backpack spray equipment or fi re bladder 

bags. Bladder bags hold approximately 5 gallons of water and can be fi lled from water trucks or 

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Figure 10.137 – The maximum 

amount of water that can be 

delivered to a root system in 

a single irrigation (y axis) is 

determined by the pipe length (x 

axis) and the diameter of the deep 

pot (lines). For example, a 14-inch 

pipe with a 1-inch diameter will 

hold approximately 0.15 quarts 

of water; a 2-inch diameter pipe 

will hold 0.75 quarts; a 3-inch 

diameter pipe will hold 1.7 quarts 

of water.

8

0.0

0.5

1.0

Water Delivery (quarts)

Pipe Length (inches)

2.5

1.5

2.0

10 12 14 16 18

3 inch Diameter

2 inch Diameter

1 inch Diameter

353
large water containers positioned in pickup beds. Assuming that an irrigator can carry 20 quarts 

of water at a time (5 gallons) and each plant in the project requires a quart of water, the applicator 

could irrigate 20 seedlings before returning for more water. If less water is required, more plants 

could be irrigated before refi lling is necessary. 

Deep pot irrigation allows for the introduction of soluble fertilizers (See Section 10.1.1) and 

mycorrhizal fungi inoculum (See Section 10.1.7) if seedlings require these treatments. Since 

soluble fertilizers are delivered directly to the roots, bypassing the soil surface, weeds are not 

encouraged to grow. Care must be taken when determining fertilizer rates to avoid increasing 

soluble salts above levels that are toxic for root growth. Salt levels and pH of the irrigation water 

must be monitored to assure that salts do not exceed toxicity levels for plant growth (See Section 

5.5.5, pH and Salts).

Determining when to irrigate can be based on the moisture stress status of the plant. An accurate 

method for determining plant moisture stress (PMS) is using a pressure chamber (Inset 10.23). This 

equipment reads plant stress (in negative bars) at the time of the readings. PMS readings should 

be made in the early morning, prior to sunrise, when diurnal PMS is at its lowest. Five seedlings 

should be collected in one area and averaged per site. If pre-dawn PMS readings are less than -15 

bars, seedlings are under high moisture stress and must be irrigated soon to keep the seedlings 

from dying. If the objective of irrigation is for fast seedling growth, then PMS during the plant 

growth (spring and fall) must be kept above -5 bars. PMS equipment is expensive to purchase. 

However, many Forest Service district offi ces use and maintain this equipment. 

10.4.5.2 Drip Irrigation

Drip (or low pressure) irrigation is generally a temporary measure to help establish roadside 

plantings. It is typically used for one or two seasons to establish nursery-grown plants and then 

removed. Setting up drip irrigation might be considered extravagant. For projects where there is no 

tolerance for seedling failure, this can be a viable, economical alternative (Bean and others 2004). 

Some advantages of using drip systems for roadsides are water effi ciency, system fl exibility, 

portability, and ease of application of soluble fertilizers. The main disadvantage is the high 

maintenance required to keep the system operational. Drip systems are composed of 

numerous points where failures can occur: storage tanks, burst end clamps, connectors, 

emitters, hundreds of feet of pipe and drip irrigation tubing. For this reason, the system must 

be inspected and maintained regularly during the summer to assure that all seedlings are being 

properly irrigated. This involves inspecting all emitters, pipes, tubing, and tanks. Emitters clog 

with sediment and insects (Bainbridge 2006c); animals gnaw through tubing when it is above 

ground; and plastic water tanks make great shooting targets. These damages to the system 

must be repaired before each irrigation cycle. Another disadvantage is that, on hilly sites, the 

system must be designed to maintain the correct pressure to each emitter.

In its simplest form, the drip irrigation system consists of: 1) a water source, 2) mainline and side 

lateral pipes, and 3) drip pipes and emitters. The system is under pressure during irrigation, 

which moves water from the water source, through the mainline and side laterals, to the 

emitters where seedlings are watered. The objective is to deliver equal amounts of water to 

each seedling. This is not a problem when the system is laid out on fl at ground and pressures 

at any point in the system are equal, but fl at terrain is seldom found on highway projects. 

On projects that have any slope gradients, there will be changes in pressure depending on 

the elevation of the emitters. The pressure change occurs at a rate of 1 lb/in2 (PSI) per 2.31 ft 

elevation drop. This means that an emitter at an elevation that is 46 ft lower than the water 

source will have a PSI of 20 (46/2.31 = 20), while an emitter at 92 ft lower than the water source 

will have a PSI of 40 (92/2.31 = 40). Unless pressure-regulating techniques are used to reduce 

the pressure to the lower elevation emitters, the amount of water delivered to those emitters 

will be approximately twice that of the upper elevation emitters. Compensating for pressure 

changes is critical for delivering equal amounts of water to each seedling. Systems that do 

not compensate will have seedlings that receive too much water, while others will not receive 

enough during an irrigation cycle.

Water Source – The water source constitutes the beginning point of the drip system. It is 

typically the most uphill point because it must feed every emitter below. Water is typically 

trucked to the site and pumped directly into the mainline, or stored in temporary, portable 

storage tanks (Figure 10.138). Water trucks range in capacity from 1,000 to 2,500 gallons. If there 

is a location for a portable water storage tank above the planting area, gravity feed can be used 

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Inset 10.23 – Measuring Plant 

Moisture Stress

(modifi ed from McDonald 1984)

Measuring plant moisture stress 

(PMS) is an accurate method to help 

determine the water needs and 

status of a plant. When a seedling 

(A) is under moisture stress, it is 

pulling water from the soil through 

the stem. The water in the stem is 

under tension, much like a rubber 

band that is being stretched (B). 

When a small branch is cut, the 

tension in the stem is released and 

the water shrinks back from the cut 

surface (C). The further back the 

water shrinks, the more moisture 

stress the plant is under. The cut 

end of the stem is placed through 

a small hole in a stopper, with the 

end protruding from the lid (D). The 

foliage is placed in the steel chamber 

and tightened so it is airtight (E). 

Nitrogen gas is slowly applied into 

the chamber, exerting pressure 

through the stomata and pushing 

water through the stem toward 

the cut end. When the water just 

begins to emerge from the cut end, 

a pressure reading is made. This is 

the amount of suction or stress that 

the seedling is under at the time the 

sample was collected. Since PMS 

varies throughout a 24-hour period, 

seedling samples must be taken in 

the pre-dawn for consistency and 

comparison purposes. 

PMS readings can be used to 

determine when to irrigate 

seedlings. If pre-dawn PMS readings 

are greater than -15 bars, seedlings 

are under high moisture stress and 

must be irrigated soon to keep the 

seedlings healthy. If the objective of 

irrigation is for fast seedling growth, 

then PMS during the plant growth 

(spring and fall) must be kept below 

-5 bars. PMS equipment is expensive 

to purchase; however, many Forest 

Service district offi ces use and 

maintain this equipment. 

Water Column in Tension

Nitrogen

Gas

PMS

(bars)

Outlet

Valve

Overpressure

Valve

Safety

Valve

ABCDEF

355
to pressurize the system. Operational 

water pressure for a drip system 

ranges from 20 to 40 PSI. To achieve 

a minimum pressure of 20 PSI with a 

gravity feed system requires a 46 ft 

elevation drop from the storage tank 

to the fi rst line of emitters (20 * 2.31 

= 46). If this drop does not exist, then 

a pump will be needed to augment 

the pressure. 

Components of a temporary water 

tank system include fi lters, on-off valve, 

backfl ow, and a pressure-reducing 

valve (if the water source pressure is 

greater than 40 PSI) (Stryker 2001). 

When planning water storage, ease of 

access is an important consideration. 

Sometimes water will need to be 

pumped a substantial distance to a 

water storage tank. In other cases, 

more than one tank will be required 

to reach all planting areas in complex 

terrain. Water from unknown sources 

should be sent to a qualifi ed lab 

and analyzed for contaminants and 

impurities (Zoldoske 1998). Chances 

are that most water sources will have 

impurities that will clog very small 

drip emitter openings. Installing a 100 

(150 micron) to 150 (100 micron) mesh 

fi lter is recommended (Stryker 2001).

Mainline and Laterals – The mainline 

delivers water from the water source 

to the lateral pipes. The layout of the 

mainline and laterals can compensate 

for pressure changes associated with 

hilly terrain. A series of parallel lateral 

lines can be laid out perpendicular to 

the slope gradient. Since each line is 

on the contour, there is no pressure 

diff erence between emitters within a 

line. Between lateral lines, however, 

there is change in pressure based on 1 

PSI per 2.31 ft elevation drop. Placing 

a pressure regulator at the connection 

between the mainline and each lateral 

line can compensate for the pressure 

increase with elevation drop.

The drip tubing diameter determines the volume of water that can be carried in the lateral 

lines and the rate it will be delivered based on friction losses. A two inch pipe, for instance, 

carries four times as much water as a one inch pipe, but the costs are correspondingly much 

higher. For long stretches, increased frictional losses inside narrow diameter pipes can cause 

inadequate water coverage. Increasing water pressures or increasing pipe diameters can 

compensate for this. 

The carrying capacity is the amount of water that specifi c tubing can deliver under a specifi c 

line pressure. For example, 0.75-inch tubing has a carrying capacity of approximately 160 

gallons per hour at a line pressure of 20 PSI, whereas 1-inch pipe has a carrying capacity of 

370 gallons per hour at the same pressure. Charts are available that compare various tubing 

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Figure 10.138 – Large holding tanks are used for 

temporary drip irrigation systems (A). A simple on/

off valve controls water to the gravity-feed system 

(B). Pressure release valves (C) are used to control 

water pressure on hilly sites. 

A

B

C

356
diameters, emitter outputs, and system pressures for determining the length of tubing. These 

charts must be referenced when designing an effi cient drip system.

Emitters – From the laterals, water fl ows through a smaller diameter pipe to the emitter, which 

meters out water directly to the base of each plant. Emitters apply water to the soil surface 

without wasting water on the surrounding area, thus discouraging non-target species. When 

emitters are placed in a deep pot irrigation system, water effi ciency is increased further 

because water is delivered directly to the roots. There are many types of emitters, but pressure 

compensating emitters work well on hilly topography because they are designed to discharge 

water at uniform rates under a range of water pressures. With pressure compensating emitters, 

a system at 15 PSI would have the same emitter fl ow rate as a system at 45 PSI (Stryker 2001). 

These emitters are two to three times more expensive than non-compensating emitters. 

Emitters come in a range of fl ow rates, with the most common rates of 2 liters/hour and 

4 liters/hour. Choosing the fl ow rate for the emitters should be based on soil texture, water 

requirements of the plants, water delivery capabilities of a system, and budget. Most designers 

agree that placing two emitters at each plant is better than one emitter with twice the output, 

because the water distribution area will more closely match the rooting profi le of the plant. 

Two emitters also off er backup should one of the emitters become clogged. 

A good grasp of the soil drainage and water storage characteristics is necessary in choosing 

emitter capacity and duration of irrigations. Well-drained soils (e.g., sandy texture or high 

coarse fragments) require emitters with higher fl ow rates, but shorter irrigation time. On the 

other hand, poorly drained soils (higher in clays, or compacted) require lower output emitters 

and longer irrigations. Size of planting stock will infl uence the number of emitters and fl ow 

rates; the larger the planting stock, the longer the irrigation cycles and more output emitters 

are needed.

There are a limited number of emitters that can be installed on any one lateral line. For example, 

0.75-inch pipe or tubing delivers approximately 160 gallons per hour, the number of emitters 

that can be installed on the line will vary by emitter output rates. Installing 0.5 gallon/hour 

emitters allows approximately 300 emitters (600/2 = 300) on the line. If two emitters were 

placed by each plant, 150 plants could be watered on a line. If the emitters were rated at 1.0 

gallon/hour, then 75 plants could be watered. 

Installation – The installation of a drip system involves placing pipe and inserting emitters. 

Tubing comes in rolls and is easiest to lay out like a wheel to keep kinks from developing in the 

line. Lateral tubing should be placed upslope from the plant, which will act like a stake should 

the tubing move downslope. Tubing migrates until it has been used for a while and may require 

periodic staking. When the main line and laterals are in their general locations, the system is 

fi lled with water to fl ush the pipes clean. The ends are clamped or plugged and then fi lled 

again. This will reveal whether there are any leaks or problems to fi x before installing the tubing 

to the emitters. A pressure gauge should be used at this time to take readings across long runs 

within or between lateral lines to check consistency of pressures. If there are problems, they 

should be corrected at this time. Puncturing tubing for emitters can be done when the system is 

charged with water, so that adequate emitter fl ows and problems are seen immediately. Some 

designers choose to bury emitters below the soil surface to reduce surface evaporation. Losing 

visual inspection, however, usually outweighs the benefi ts of this strategy (Zoldoske 1998).

Operation – Prior to operating the drip system, fi lters must be cleaned. Check salt levels and pH 

of the irrigation water using a pH/conductivity meter to assure that salts do not exceed toxicity 

levels for plant growth (See Section 5.5.5, pH and Salts). Once these measures have been taken, 

the system can be opened and lines and emitters inspected. If emitters need cleaning, repair, 

or repositioning, it is done at this time. Tools and spare parts for the system are brought along 

and used where needed. Determining when to irrigate should be determined through PMS 

monitoring (Inset 10.23). Determining the duration of the irrigation cycle can be done once or 

twice during the growing season through a visual inspection soil profi les dug below several 

emitters. Observing the wetting front should be done several hours after the system has been 

shut off because the wetting front will have stabilized at that time. 

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11 MONITORING AND MANAGEMENT 

11.1 INTRODUCTION

The goal of roadside revegetation is to establish healthy, functional communities of native 

plants along roadsides and on road-related disturbances. However, projects to establish native 

plants on disturbed sites rarely turn out exactly the way they were planned. Therefore, regular 

visits to the project to evaluate progress, and to intervene if necessary, are essential parts of the 

revegetation process.

Monitoring is carried out for two reasons: 1) to correct, manage, and maintain the project 

eff ectively, and 2) to learn lessons for future projects. Monitoring provides the answers to the 

following questions:

 · Is native vegetation establishing well, or is some corrective action needed? 

 · Were regulatory standards or revegetation commitments met?

 · Were there diff erences in plant responses between diff erent revegetation treatments?

These questions may be answered simply through general observations during routine fi eld

visits, through formal photo point monitoring, or through statistical methods. Monitoring 

begins during the implementation phase and continues after the project has been installed. 

A general monitoring protocol that can be applied to all revegetation projects does not exist. 

Instead, monitoring should be tailored to the objectives of each project and to the uniqueness 

of the site. It is important to determine in advance whether formal data collection and statistical 

analysis is necessary for the project. Simple fi eld visits or photo point monitoring may provide 

suffi cient information to determine whether objectives have been met. This chapter discusses 

general monitoring and management steps. If statistical methods will be necessary, Chapter 

12 outlines some statistical monitoring protocols that cover the most common roadside 

revegetation objectives and conditions.

Information collected during monitoring will guide management and maintenance activities 

for the current project. This information can also be used to improve revegetation techniques 

for future projects. Monitoring completes the project cycle by providing feedback regarding 

the success or failure of a revegetation project. This information is used to adapt and improve 

other projects that are in the initiation, planning, or even implementation phases of the other 

project cycles (Figure 11.1).

Monitoring can also play an important role in advancing the knowledge and understanding of 

establishing native plants on highly disturbed sites. This relatively new fi eld of study lacks basic 

fi eld-tested techniques. With well-designed monitoring projects, the revegetation specialist 

can provide valuable information for the use of native plants in revegetating harsh sites.

The monitoring and management phase of the project involves several steps:

 · Revisit project objectives and DFCs,

 · Develop monitoring strategy and protocol(s),

 · Record data and observations,

 · Evaluate data and apply any corrective measures,

 · Organize and file project results, and

 · Share lessons learned.

Monitoring information is utilized to evaluate progress and to inform any management activities 

needed to correct the results. Long-term road maintenance and management is usually the 

responsibility of the road-owning agency. However, monitoring information can facilitate 

long-term results and help inform management even after the revegetation specialist’s role 

is completed.
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Summary

The

Project

Cycle

Initiation

Adapt

and

Improve

Initiation

of

Future Projects

Monitoring/

Management

Implementation

Planning

Figure 11.1 – Monitoring 

and Management are the 

fi nal components of the 

project cycle. Monitoring 

guides management 

actions for the current 

project, and provides 

valuable information to 

improve future projects. 

Management actions 

can correct shortcomings 

in results.

359

11.2 REVISIT PROJECT OBJECTIVES AND DFCS

A common pitfall in many monitoring projects is the lack of clearly stated objectives or 

reasoning behind data collection. A good monitoring project is not defi ned by the amount 

of data collected, but by whether the data adequately and effi ciently determines whether the 

objectives of the revegetation project were met. This question can only be addressed when the 

objectives for monitoring are clearly stated. Monitoring eff orts must not only link back to the 

original project objectives, but also to the specifi c DFCs developed in the planning phase (See 

Chapter 4). Objectives and DFCs set the standards (sometimes called “performance standards,” 

“thresholds,” or “indicators”) against which the project is evaluated (Clewell 2004).

DFCs are often stated in quantitative language. For example, the DFC for a cut slope three 

years after construction is stated in the revegetation plan as “less than 25% bare soil will be 

exposed” and “vegetative cover will be composed of greater than 70% native species.” These 

DFCs are very specifi c and can be used as target values, or thresholds, for determining whether 

or not the project was successful. Monitoring methods, or protocols, are developed specifi cally 

around each of these targets or thresholds. When monitoring is approached in this manner, 

only the information needed to determine whether targets were met is collected. Expensive, 

superfl uous data collection is avoided because the DFCs were clearly defi ned.

11.3 DEVELOP MONITORING STRATEGY AND PROTOCOL(S)

The DFCs identify what will be monitored and defi nes the minimum acceptable thresholds. The 

monitoring strategy defi nes how those criteria will be measured and evaluated. This involves 

issues of scope (what level of detail or certainty is needed?), methods (what is the best way 

to obtain the necessary information?), and location, timing, and frequency (where, when, and 

how often should monitoring take place?). After the information is collected, the DFC threshold 

values will be used to evaluate success or failure, in order to determine if results are acceptable 

or if corrective action is required.

A monitoring protocol is a specifi c set of directions that outlines, step by step, how the 

monitoring will actually take place in the fi eld. Sometimes several diff erent protocols will be 

utilized on one project. The monitoring strategy sums up the monitoring protocols and creates 

a comprehensive map, schedule, and budget for monitoring activities for the project.

11.3.1 Defi ne Scope

Scope defi nes the level of monitoring detail. Some portions of the revegetation project might 

require only a project diary and a series of photographs while other areas within the project will 

require a statistically designed monitoring protocol. At a minimum, most projects require annual 

visits and recorded observations or qualitative assessments. Portions of revegetation projects 

may require statistically-based monitoring to ensure regulatory compliance and accountability. 

For example, if water quality standards dictate that road sections near a high-value fi shery have 

no greater than 20% bare soil the fi rst year after construction for sediment control, the importance 
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360

of this project to fi sheries and water quality will require high confi dence in the accuracy of the 

data. This might require more intensive data collection and statistical analysis to ensure a higher 

level of certainty. On the other hand, road sections that do not aff ect the stream system would 

have less need to collect data for statistical analysis of this intensity. In such cases, qualitative 

assessments such as photo point monitoring or fewer sampling points may suffi ce (Inset 11.1). In 

general, the scope of monitoring should refl ect the importance of the revegetation objective and 

the ecological sensitivity of the project site and surrounding areas (See Chapter 12).

11.3.2 Determine Location, Timing, and Frequency

Choosing appropriate sampling areas to assess whether project objectives were met is a 

foundation of a good monitoring strategy. Some revegetation projects can be complex and 

cover many acres. For these projects, it is important to identify specifi c monitoring areas. 

However, not every area needs to be monitored. The revegetation unit is usually the basic unit of 

sampling. There should be little reason to split out the revegetation units in order to determine 

whether standards or thresholds were met. Finer delineation of areas within revegetation units 

for monitoring should only be done if there are specifi c questions to answer about treatment 

eff ectiveness or diff erences. 

Determining the most appropriate time of the year and frequency for monitoring is a key part 

of developing a monitoring strategy. Some portions of a revegetation project may require only 

one monitoring visit, which may simply be carried out as part of quality control during the 

implementation phase (See Chapter 9). For example, if a two-inch application of composted 

mulch is a stated objective in the revegetation plan, then one visit to the site, preferably during 

mulch application, will suffi ce to confi rm whether this occurred or not. For other objectives, a 

series of observations over time will be necessary. For example, a planting contract requires 

400 live trees to be established the fi rst year after planting and 300 live trees by the third year. 

This project would need to be monitored twice, once at the end of the fi rst year and once in 

the fall of the third year.

It is important to defi ne the season that monitoring will take place because vegetation changes 

from season to season. This will aff ect the results of the data being collected. For instance, if the 

monitoring objective is to determine the species cover after seeding native grasses and forbs, 

monitoring should take place in the early summer when plants are fl owering and species are 

easily identifi able. Collecting soil cover data, on the other hand, is often done in the fall prior 

to winter rainstorms, since the revegetation specialist will want to know the amount of ground 

cover that will be protecting the soil during these events. Monitoring fi rst year seedling survival 

should be done in fall and not in spring or summer. Taking data in spring or summer will show 

higher survival; by fall, most of the seedling mortality will have occurred. 

11.3.3 Develop Sampling Methods

Sampling methods defi ne what parameters will be measured and how the data will be collected. 

Parameters may be biotic or abiotic, and are determined by the revegetation objectives. 

For example, vegetative cover can be measured as basal cover or aerial cover. If the objective 

is erosion control, then basal area is usually measured. If the revegetation objective is visual 

aesthetics, then aerial cover would be selected. In another example, if a revegetation objective 

is to reestablish a working group of species, then measuring for species presence would 

be conducted. If this is the case, the interest is only in working group species, so only these 

species need to be monitored. Any other species can be grouped into broader categories, such 

as grasses and forbs, for measurement. This strategy reduces the need to identify all species 

present in a sampling unit, and instead focuses data collection on the key species or groups of 

species that are relevant for meeting project objectives.

11.3.4 Summarize Monitoring Strategy

The monitoring protocol or protocol(s) to be utilized to evaluate the progress should be 

summarized into an overall monitoring strategy (Table 11.1). The monitoring strategy should 

have these components (Elzinga and others 1998):
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 · Summary of objectives. The purpose for monitoring, the project objectives and DFCs to 

be met, DFC “threshold values” for success or failure on each revegetation unit.

 · Monitoring area map. The monitoring area map locates and identifies all monitoring 

areas in the road project area. For example, the monitoring areas identifi ed in Table 11.1 

would each be located on a road map.

 · Summary of monitoring protocols. The strategy summarizes the general type of 

monitoring, including scope, location, timing, frequency, and sampling methods for 

monitoring each revegetation unit (Table 11.1).

 · Consolidated timelines. A comprehensive timeline should be developed for the entire 

project, detail the schedule for how each revegetation area will be monitored, and 

include the due date for the Final Monitoring Report.

 · Expertise. Some monitoring protocols will require specific expertise in botany, soils, 

or other natural resource disciplines. This should be addressed in the strategy to make 

sure these resources are available.

 · Costs. A general estimation of costs can be made once the monitoring protocols have 

been selected. It is important to take stock of the budget at this point since this is the 

fi nal phase of the revegetation project and there must be enough funding to implement 

the monitoring.

 · Monitoring oversight. One person must have oversight of all monitoring activities; it is 

the responsibility of this person to ensure that the protocols are being implemented 

within the timelines that were developed. This person completes the fi nal monitoring 

report and summarizes important fi ndings.

Table 11.1 – Example of a basic monitoring summary. This table, accompanied by a map of the 

revegetation project, are the basic elements of a monitoring strategy.

Revegetation 

Unit DFCs or Objective Monitoring Protocol Year

Expertise 

Required

1

Steep Cut 

Slope

- Photo point 0, 1, 3, 5 -

70% soil cover Soil cover 1 -

90% soil cover Soil cover 3 -

60% native 

vegetation

Species presence 3 Botany

Nitrogen analysis Soil samples 2 Soils

2

Obliterated 

Road

- Photo point 0, 1, 3, 5 -

400 live trees 

per acre

Plant survival 1 -

300 live trees 

per acre

Plant survival 3 -

4 foot average 

tree height

Plant growth 3 -

3

Wetland

- Photo point 0, 1, 3, 5 -

80% survival 

of plants

Plant survival 1, 3 -

70% native 

plant cover

Species cover 3 Botany

No invasive plants Invasive plant survey 1, 3 Botany
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11.4 RECORD DATA AND OBSERVATIONS

With the monitoring protocols defi ned and the overall strategy in place, data and observations 

can be recorded as schedules. Methods of data collection can be qualitative or quantitative, 

complex or simple. No matter what methods are to be utilized, clear written instructions in 

the protocols will outline exactly how data is to be collected. Chapter 12 illustrates the most 

common statistically-based monitoring protocols needed to meet most roadside monitoring 

objectives. The protocols must still be used in the context of the unique environmental and 

operational characteristics of the revegetation unit. For example, accessibility to a cut slope 

for monitoring soil cover might be limited due to very steep slope gradients. Although the 

soil cover monitoring protocol would be selected, modifi cations would be necessary to assure 

personnel safety. The modifi ed protocol would not be the same as one developed for areas 

where slope gradients are gentle. Keep good records of the information that is collected. 

A fi eld monitoring form (such as the example provided in Table 11.2) is a useful tool to keep 

information organized and consistent as measurements are taken over time. 

11.5 EVALUATE DATA AND APPLY ANY CORRECTIVE MEASURES

There is no purpose in monitoring if the information will not be appropriately analyzed. 

The primary reasons monitoring data is not analyzed may include: 1) the monitoring plan was 

too complicated (massive amounts of data were generated); 2) insuffi cient thought was given 

to analytic methods; 3) monitoring was not designed in a meaningful or statistical manner; 

or 4) the monitoring objectives were poorly stated. Chapter 12 addresses these issues and 

presents strategies to streamline monitoring so that only essential information is collected and 

data can be quickly and easily analyzed.

Analysis of the monitoring data provides the feedback needed to identify and correct problems 

as they arise (Figure 11.1). There are many reasons corrective actions may be necessary as 

the project develops. This may include unanticipated events, such as unforeseen invasion/

infestation of weeds or other pests, theft or human impacts, or unforeseen weather events, 

such as drought or early frost. In addition, there may have been some erroneous assumptions 

during the planning phase about either the appropriate future conditions for the site, or 

about the appropriate method to achieve the desired conditions. The sooner issues can be 

identifi ed through data collection and analysis, the sooner (and more economically) they can 

be corrected. This is the basis of good management. 

Table 11.2 – Example Field Monitoring Form (adapted from Elzinga and others 1998).

Project name:

Dates of data collection:

Personnel: 

Location of monitoring (attach map and GPS coordinates):

Revegetation unit:

Revegetation treatments: 

Desired future conditions (DFCs): 

Sampling objectives: 

Monitoring protocol (soil cover, species presence, species cover, etc.):

Sampling design (size and shape of sampling unit):

Number of transects or quadrats:

Type of data analysis:

Description of codes (on map or in notes):

Notes and location of accompanying map and data fi les:
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Inset 11.1 Photo Point Monitoring

(Adapted from Hall 2002a, 2002b)

Photo point monitoring is a method of displaying landscape changes in vegetation over 

time. If a picture is worth a thousand words, photo point monitoring is often a useful way to 

show the success or failure of a revegetation project. Landscape images from photo point 

monitoring, in conjunction with data collected from other monitoring methods, can be 

very eff ective in describing the results of revegetation eff orts. Hall‘s Photo Point Monitoring 

Handbook (2002a, 2002b) provide more thorough coverage of the subject.

Locating photo points. The fi rst step in photo point monitoring is to establish where the 

photo will be taken. The locations of the photo point should be based on the objectives of 

the revegetation project. These should include the important aspects of revegetation to 

document over time. For example, if the objectives for revegetation are visual enhancement, 

photo points should be located in the best places for showing these changes over time. 

The eff ects that vegetative growth will have on the line-of-site as vegetation matures should 

also be considered. Small shrub and tree seedlings planted along roadsides will, with time, 

fi ll in the entire picture frame, obscuring any long-distance views. To avoid this, the location 

and direction of the camera should place the road corridor in the foreground, since the road 

corridor will always be free of vegetation.

Photo point locations should be described in detail to be easily located years later by 

personnel other than the person who took the original photograph. Permanent structures 

that can be easily described and located by others make good reference points for photo 

locations. These include culvert inlets and outlets, guardrail posts, mile post markers, road 

signs, road intersections, telephone poles, and other types of permanent utility structures. 

Since these features are not always permanent, it is important to locate more than one 

structure in the fi eld.

The photograph is either taken from the permanent structure or from a measured distance. 

For example, a photographer might decide to take a picture on the fog line directly above 

a culvert outlet. This spot would be easily described and locatable in the fi eld by another 

person several years later. A photographer might also locate a site at a permanent sign post 

or by counting the number of posts in a guardrail back from a known spot. An azimuth 

reading and measured distance from the structure should be recorded in the notes.

A common method for locating a photo point is to drive a stake (rebar) at the spot. This 

method works but has some drawbacks: the stake must be set back far enough so that it 

does not interfere with maintenance activities or traffi c safety; the stake must be driven 

several feet into the soil, which is limiting on most cut slopes and some fi ll slopes; and the 

stake must be identifi ed with a tag that is readable over time. One problem associated 

with poorly placed stakes is that they are often displaced through active soil movement, 

animal traffi c, vandalism, or road maintenance activities. Utilizing a permanent feature of 

the roadside, such as a guardrail or signpost, is generally a better alternative. GPS points can 

also help locate photo points. 

The camera. Digital and fi lm cameras are both acceptable for photo point monitoring. 

For digital cameras, a dpi setting of 2280 by 1800 (4.1-megapixel or higher) should be used 

to obtain adequate resolution. For fi lm cameras, a ISO rating of 100 should be used. Using 

cameras with good lens quality is also essential for optimum photographs. Avoid using the 

zoom lens because this feature can pose problems in reproducing the original photograph 

(Hall 2002b). 

Taking the fi rst picture. The camera is set on a tripod over the identifi ed photo point 

location and image is previewed on the LCD screen or through the lens. With a compass 

aligned to the side of the camera, an azimuth reading is taken. (Be sure that the declination 

of the compass is defi ned in the notes.) Using a clinometer on the top of the camera, the 

degrees from horizontal are recorded. 
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Keep a log or electronic document that includes the following information about the 

photograph being taken:

 · Photograph name;

 · Project name;

 · Date;

 · Time;

 · Photographer;

 · Location on plan map;

 · Location description;

 · Azimuth of camera;

 · Angle of camera;

 · Manufacturer and model of camera;

 · Focal length;

 · Brand, type of film, and ISO rating 

(for fi lm cameras); and

 · Large imported jpeg image of 

photograph.

Photo data bases, where this information is tied directly to the image, are great storage 

systems for electronic photographs. Digital images can also be fi led with the hard copies.

Taking subsequent photographs. At later dates, the photo point is relocated using the 

map, photo, GPS point, and/or and location description. The camera azimuth and vertical 

angle is set, and the image is viewed through the LCD screen or lens and compared to the 

print of the original photograph. If the original spot cannot be located, then relocating the 

photo point can be attempted using the procedures outlined in Figure 11.2.

A

3

1

2

3

1

2

B

Figure 11.2 – If no records exist for the 

original photo locations, then a close 

approximation can be determined 

(after Hall 2002a). If the photographs 

were taken along a roadside, it is often 

possible to relocate the approximate point 

the photograph was taken by locating 

permanent structures (such as guardrails 

and culverts).

To relocate the photo point in the historic 

photograph (A), a large print was made 

and taken to the general location in the 

fi eld. Since the original photograph was 

obviously taken from the paved road 

surface on the inside of the guardrail, 

there was little doubt that the elevation 

of the second photograph (B) would be 

approximately the same.

Locating the original photo point along the 

guardrail was accomplished by establishing 

a relatively vertical centerline connecting 

two identifi able points on both the original 

photograph (A) and the photograph to be 

taken (B). In this example, the centerline is 

drawn from the left side of the culvert (1) 

to the 12th post of the guardrail (2) from 

the refl ector stake (3). Picture B is a close 

approximation to the photo point location 

of photo A, but notice that the centerline 

is not quite in the same direction as in 

photo A. To fi nd the more exact location, 

the photographer should move to the right 

along the inside of the guardrail until the 

centerline lines up in the same direction as 

in photograph A.
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11.6 ORGANIZE, FILE AND REPORT PROJECT RESULTS

Monitoring is a long-term eff ort that can span many years. It is important to document, organize, 

and fi le monitoring information in a manner that will be understandable to others years later. 

The cover sheet illustrated in Table 11.2 is useful to attach to the front of a monitoring data set 

when fi ling. It details the date, location, and methods of monitoring.

Be sure that the project records include:

 · The diary or log kept during the project,

 · Copies of all maps and plans,

 · Copies of all budgets and task orders,

 · Photos and data, and

 · Reports and evaluations.

Depending on the complexity of the project and the agencies involved, some reporting of 

monitoring results will be necessary. Reports are an excellent opportunity to summarize the 

information collected and describe any management actions taken to correct shortcomings.

Timing varies, but typically, a Final Monitoring Report is submitted after the third monitoring 

season. This report summarizes whether the revegetation project met standards and 

commitments made during the planning stages. It is important to review the original 

revegetation plan to address whether the desired future condition was fulfi lled as stated. 

The report should address this in the context of successes or failures in each revegetation unit.

11.7 SHARE LESSONS LEARNED

Revegetating highly disturbed sites with native plants is a relatively new fi eld of study. 

Well-designed and analyzed monitoring projects can provide good information to a wider 

audience of practitioners and scientists working in this fi eld. By taking the time to share monitoring 

results, the science and practice of revegetating highly disturbed sites can be advanced.

Conferences, societies, newsletters, internet sites, and trade publications are some venues to 

share knowledge. The small-scale trials that were carried out to test, for example, diff erent rates 

of fertilizer, tackifi er, seeds, or hydromulch should also be of great interest. Case histories or 

trials can be shared on websites, in journals, or in posters and presentations at conferences 

(SER 2005). Evaluations of the overall approach taken and the lessons learned will be an 

important contribution to future projects.

11.8 ROADSIDE MAINTENANCE AND MANAGEMENT

Following road construction, maintenance of roadside revegetation is usually administered 

by local agencies. Once the fi nal revegetation report is submitted and the reimbursable 

agreement is closed, maintenance and monitoring of vegetation is no longer the responsibility 

of the revegetation specialist. However, coordination with the road maintenance agency is vital 

to ensure the long-term success of the project. Monitoring information can help guide eff ective 

decision-making for the life of the project site. While specifi c maintenance strategies are beyond 

the scope of this manual, many resources exist to protect and enhance native vegetation 

on roadsides and to reduce the spread of invasive species. For example, on a national level, 

guidelines have been developed for Integrated Roadside Vegetation Management (IRVM) to 

maintain healthy populations of native plant communities to exclude invasive species (Berger 

2005). Many road-owning agencies have their own protocols for monitoring and managing 

roadsides. Readers are encouraged to explore these resources in order to support the goal of 

healthy native plant communities on roadsides.

11.9 CONCLUSION

Roadside revegetation is an integrative process that involves careful planning, implementation, 

and monitoring. It is important to select monitoring strategies that generate useful information 

targeted to project objectives and DFCs. Analyzing and sharing results is a key practice to guide 

eff ective management of the project, as well as to improve results on future projects.
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Figure 12.1 – Quick Guide to Monitoring 

Chapter. 

What are you monitoring?

What is the shape of the sampling area?

What is the objective for monitoring?

Read

Soil Cover 12.2

12.3

12.4

12.5

12.6

Species Cover

Species Presence

Plant Density

Plant Attributes

12.7.2

12.7.1

Rectilinear

Dispersed 12.7.3

Linear

12.9.2

12.9.1

Treatment Differences

Trends 12.9.3

Compliance

366

12 MONITORING PROTOCOLS

12.1 INTRODUCTION

This chapter describes statistical sampling design, data collection techniques, and analysis 

methods for quantifi able parameters to determine success of roadside revegetation projects. 

It is written specifi cally for fi eld personnel as a quick guide to monitoring roadsides. It is not 

intended to teach statistics or explain the statistical basis behind the procedures addressed in 

this section. If the reader wishes to explore the statistics used in this chapter, a supplemental 

report (Kern 2007) details the statistical basis for each procedure. There are many approaches to 

statistically monitoring roadside vegetation. This report takes the approach that if monitoring 

is not simple, inexpensive, and objective-based, it will not be done well, or done at all.

The reader will be directed to those sections necessary to prepare and implement a monitoring 

plan. Three questions must be to answered before monitoring begins:

1) What are you monitoring?

2) What is the shape of the sampling area?

3) What is the objective behind monitoring?

The answers to these questions will lead the reader to diff erent parts of the chapter (Figure 12.1). 

This chapter presents methods to record, summarize, and analyze data using the Excel® 

spreadsheet program. You can create your own spreadsheet, or obtain a monitoring Excel® 

workbook which contains the spreadsheets shown in the chapter by contacting the authors 

of the report. Before using the spreadsheets, the reader is advised to see whether the Analysis 

ToolPak is installed. If it is not, many of the spreadsheets will not function properly. To do this, 

go to the toolbar and select Tools, Add-Ins, then make sure that the box next to Analysis ToolPak 

is checked.

What are you monitoring? There are many 

revegetation parameters that can be monitored. 

In this chapter, parameters are grouped 

into 5 categories based on the following 

revegetation objectives:

 · Soil cover – to determine whether 

treatments increased soil cover for 

erosion control.

 · Species cover – to determine whether 

treatments increased native grass and 

forb cover.

 · Species presence – to determine whether 

there was an increase in the number of 

seeded native grass and forb species.

 · Plant density – to determine how many 

seedlings or cuttings became established 

after planting to assess whether stocking 

is adequate or the site needs replanting. 

Plant survival can also be determined 

from this protocol.

 · Plant attributes – to determine how fast 

planted shrubs and trees are growing.

The procedures for monitoring each of 

these parameters are described in Sections 

12.2 through 12.6. Each protocol discusses how 

Note: This chapter uses abbreviated scientifi c names, or plant symbols, from the PLANTS Database 

(http://www.plants.usda.gov) to conserve space in spreadsheets. The PLANTS Database includes scientifi c names, plant 

symbols, common names, distributional data, images, and species characteristics for vascular plants of the United States.
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transects and quadrats (or plots) are located, methods for collecting data at each plot, and how 

data is summarized for statistical analysis.

What is the shape of the sampling area? Revegetation projects associated with road 

construction can be classifi ed into three broad sampling design categories based on the spatial 

features of the sampling unit:

 · Linear areas – associated with cut slopes, fill slopes, and abandoned roads

 · Rectilinear areas – associated with staging areas and material stock piles

 · Dispersed areas – associated with planting islands, planting pockets, clump plantings

Each of these sampling designs has a set of procedures defi ning how transects and quadrats 

will be laid out. Section 12.8 guides the reader through methods for determining how many 

transects and quadrats to establish.

What is the objective behind monitoring? There are three basic reasons for 

statistical monitoring:

 · Compliance – were regulatory standards or project objectives met?

 · Treatment diff erences – are there differences between revegetation treatments?

 · Trends – what degree of change is occurring over time?

Monitoring for most projects will be conducted to determine whether standards were met 

(compliance) since this will be of most interest to the reviewing offi cials. There will be occasions 

however, when you might want to know if diff erent revegetation treatments applied to the 

same area resulting in a diff erent vegetative response. There might also be times when it will 

be important to know to what degree things have changed over time. It is important to discern 

which of these three objectives meet the intent of your monitoring. 

As you move through this chapter to the appropriate sections, you will develop, by the end, a 

set of instructions that establish:

 · Quadrat locations (See Section 12.7)

 · Quantity of quadrats to take (See Section 12.8)

 · Type of data collection at each quadrat (See Sections 12.2 through 12.6)

 · Type of data analysis to perform (See Section 12.9)

These instructions should be developed prior to any monitoring work and organized in a 

manner that is easy to reference in the fi eld. 

12.2 SOIL COVER PROTOCOL

Reestablishing grasses and forbs on disturbed sites is essential for erosion control. In general, 

erosion and sediment transport is a function of live or dead cover in contact with the soil 

surface. Soil cover protocol can be selected to determine the amount and type of cover existing 

on the surface after construction.

The quadrat is the unit of area that is monitored for soil cover. Exact measurements are based on 

recording the surface soil attributes at 20 data points within each quadrat. In this assessment, 

a grid of 20 data points is placed on the surface of the soil; where each point hits the surface is 

where the soil cover attribute is recorded. For instance, the data recorded at the fi rst quadrat 

shows that 5 points were rock, 10 points were live plant cover, and 5 points were soil. The results 

for that quadrat would be 25% rock, 50% live plant cover, and 25% bare soil.

Quadrats are read in the fi eld using a fi xed frame (See Section 12.2.1), or read later in the offi ce 

from digital pictures of quadrats. A system for taking digital photographs of the surface, where 

the photograph itself becomes the quadrat, is described in Section 12.2.2.

The sampling design for laying out transects and quadrats depends on the shape of the 

sampling unit (See Section 12.7). The number of transects and quadrats depends on the 

variability of the parameter of interest (See Section 12.8). How the data will be analyzed will be 

based on the objectives for monitoring (See Section 12.9). These sections should be reviewed 

before this protocol is used.
Figure 12.2 – A fi xed frame for measuring 

soil cover is placed at predetermined 

distances on a transect.

Figure 12.3 – A fi xed frame can be adapted to 

allow for the positioning of a laser pointer at 

20 points in the frame. Soil cover or plant cover 

attributes are recorded at each laser point. The 

frame in this example is 8 in by 20 in, with 2 in 

spacing within rows and 4 in spacing between 

rows. The laser is a Class IIIa red laser diode 

module that produces a 1mm dot.

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12.2.1 Sampling by Fixed Frame

Soil cover is quantifi ed at each quadrat based on readings from a 20 point fi xed frame. There 

are several types of frames that have been developed. The most appropriate frames are 

1) light weight and portable, 2) stable, and 3) easy to assess data points on the ground surface. 

One frame that meets these criteria uses a laser pointer to identify data points. The frame 

shown in Figure 12.3 has 20 slots to position a laser pointer. During monitoring, the laser 

pointer is moved to each of the 20 slots. Soil cover attributes are recorded where the laser hits 

the ground surface. Contact the authors of this report for more information on this frame.

The fi xed frame must be located along the tape in a consistent manner throughout the 

sampling of a unit (Figure 12.2). For instance, the frame might be placed on the right side 

of the tape with the lower corner of the frame at the predetermined distance on the tape. 

This procedure would be applied across the entire sampling area. The legs of the frame are 

positioned so that the surface of the frame is on the same plane as the ground surface (Elliot 

personal correspondence 2007).

Each data point is characterized from a set of predetermined label descriptors which include, 

but are not limited to:

 · Soil

 · Gravel (2mm to 3 inches)

 · Rock (> 3 inches)

 · Applied mulch

 · Live vegetation (grasses, forbs, lichens, mosses)

 · Dead vegetation

Ideally, one would quantify only cover in contact with the soil surface. However, diff erentiating 

between plant leaves and stems that are in direct contact with the soil as opposed to simply 

in close proximity to the soil surface can be diffi cult and not always feasible. In this protocol, 

the assumption is that if live or dead vegetation is within one inch of the soil surface, it will be 

recorded as soil cover.

Diff erent levels of vegetative cover will block the view of the soil surface. To circumvent this 

problem, the quadrat will be clipped of standing vegetation (dead or alive) at a one inch height 
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A2 fx Transect

A

1

2

3

TransectQuadratSoilGravelMulchLive VegDeadVegTotal PointsSoilGravelMulchLive VegDeadVeg

4

5

6

7

8

9

1

1

1

1

2

2

1

2

3

4

1

2

3

4

0

1

3

0

5

7

1

2

5

1

6

8

12

8

12

10

3

1

3

3

0

6

3

0

4

6

0

3

20

20

20

20

20

20

15

20

0

5

15

0

25

35

5

10

25

5

30

40

60

40

60

50

15

5

15

15

0

30

15

0

20

30

0

15

Sampling Area:

B CDE F G H I J K L M

Number of Points % of Points

H M

Total Points

% of Points

=C3 =D3 =E3 =F3 =G3

=SUM (C4:G4) =C4/20*100 =D4/20*100 =E4/20*100 =F4/20*100 =G4/20*100

=SUM (C5:G5) =C5/20*100 =D5/20*100 =E5/20*100 =F5/20*100 =G5/20*100

I JKL

Figure 12.4 – A data collection and summary form can be developed similar to the fi rst 7 

columns in this spreadsheet. The fi eld recorder fi lls in the transect and quadrat number at 

each plot (columns A and B). The names of the attributes being sampled are written in cells 

C3 through G3. The columns below each attribute (columns C through G) are fi lled in with the 

number of points out of 20 that fall into each category. These points are converted into percent 

of total points by copying the equations from columns H through M. Filling in the equations can 

be done simply and accurately by fi lling out the fi rst row (cells H4 through M4) exactly as it is 

shown in the fi gure, then highlighting the fi rst row of cells, and moving the cursor to the lower 

right hand corner of the last cell. When the cursor turns into a small cross, click and drag the cells 

down. The equations will fi ll in as you drag the curser down the page. Note: Rectilinear study 

areas will not use the transect column.

369

above the ground surface prior to taking the readings. The clipped vegetation is removed 

from the plot before the reading is made. This method errs on the side of lower ground cover 

readings because the standing vegetative material that is clipped and removed would have 

eventually become ground cover.

Data can be recorded on a fi eld-going computer or on paper. Recording data on paper bypasses 

the need for electronic equipment in the fi eld. However, it requires that data be entered into a 

computer at a later time. The development of a paper form should consider how data will be 

entered and statistically analyzed. Figure 12.4 shows a spreadsheet for collecting data which 

also will summarize the data by % of surface in a cover attribute.

12.2.2 Sampling by Digital Camera

Digital cameras are being used more and more frequently for monitoring plants and animal life. 

This technology allows the data collector to spend most of the fi eld time laying out transects 

and taking pictures of quadrats, reducing fi eld time signifi cantly. With recent developments 

in photo-imaging software, photos can be assessed quickly back in the offi ce. Because these 

are permanently stored records, digital photographs have several advantages: 1) photographs 

can be reviewed during the “off ” season or “down time,” 2) they are historical records that can 

be referenced years later, and 3) they can be reviewed by supervisors for quality control. In 

addition, taking digital photographs of ground cover can be accomplished by one person, not 

two as is often required of fi xed frame monitoring. On steeper slopes, using a digital camera to 

record quadrats is much quicker and simpler than reading attributes from a fi xed frame which 

is often very diffi cult (Figure 12.6).

Sampling by camera requires the same statistical design and plot layout as the fi xed frame 

method. The diff erence is that a picture is taken at the quadrat location instead of on-site 

measurements. In the offi ce, digital photographs are catalogued electronically and a 20-point 
Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring 

Protocols

Summary

Figure 12.6 – Road cuts are often 

too steep for sampling without the 

aid of ladders or ropes. A hazard 

analysis must be conducted prior to 

implementing such measures. For 

the monitoring shown in this picture, 

a camera was used for the soil cover 

protocol which cut down the amount 

of time spent on the ladder (Photo by 

Greg Carey).

Figure 12.5 – For the soil cover protocol, 

a 20 point grid is randomly positioned 

on a digital photograph of the plot. Soil 

cover attributes are identifi ed where 

the point hits. In this example, there are 

8 “soil” points (40%), 3 “grass” (15%), 

7 “dead vegetation” (35%), and 2 “straw 

mulch” (10%).

370

overlay is placed on the image that identifi es the data points to be described (Figure 12.5). The 

data points are described in the same manner as the fi xed frame method.

Prior to photo monitoring, the resolution of the images must be determined. Setting the 

camera at the highest resolution is fi ne provided the camera has the memory capacity to 

store large images. It is possible that over a hundred digital images will be recorded for each 

sampling area. When memory is limiting, it is important to select the minimum resolution 

that will allow fi ne surface details to be observed. Resolution should be determined for each 

camera by taking photos of a soil surface at several camera settings (see the camera manual) 

and viewing them on a computer screen to determine whether photos are detailed enough for 

accurate measurement of the soil cover attributes. It is important to have enough memory to 

store the number of pictures required. Carrying extra memory (as well as an extra battery) is 

always a good idea.

The camera should be secured to a tripod at a fi xed height between 3 to 5 feet above the 

ground surface. The camera height should be adjusted so it is comfortable for the person 

sampling while still capable of capturing the image within a photo frame. A photo frame 

defi nes the area within which the photograph will be taken. The frame can be easily made from 

PVC pipe joined together with pipe connectors. There is not a standard frame size however, an 

11 in by 14 in frame seems to work well. Prior to each photograph, the transect/quadrat must 

be recorded within each frame so that each image can be accurately identifi ed later. This can be 

done with by writing the number on small tags or paper and included in a corner of the frame. 

Quadrat identifi ers are abbreviation of the transect and quadrat numbers (e.g., “4-2” represents 

the fourth transect/second quadrat).
Roadside

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Introduction

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Summary

Figure 12.7 – This spreadsheet can be used to summarize species cover data and is similar to 

Figure 12.4. Fill in the names of the seeded species in cells C3 through G3. Beneath each species, 

report the number of points that were encountered for each species. The corresponding 

percent cover for each species will show up in the formula cells. Insert additional rows and 

columns if more are needed. Note: Rectilinear study areas will not have the transect column 

fi lled in.

P4 fx

A

1

2

3

Transect /DispersedUnitQuadratELGLBRCA5FECAERLAERUMTotal PointsELGLBRCA5FECAERLA

4

5

6

7

8

9

1

1

1

1

2

2

1

2

3

4

1

2

3

4

0

1

3

0

5

7

1

2

5

1

2

4

6

4

5

3

3

1

3

3

0

6

3

0

4

2

0

3

20

20

20

20

20

20

15

20

0

5

15

0

25

35

5

10

25

5

10

20

30

20

25

15

15

5

15

15

0

30

80

80

70

60

65

65

B CDE F G H I J K L N ERUM 15

0

20

10

0

15

M

Number of Points % of Points

M N

% of Points

=C3 =D3 =E3 =F3 =G3

=C4/20*100 =D4/20*100 =E4/20*100 =F4/20*100 =G4/20*100 =SUM(C4:G4)/H4*100

=C5/20*100 =D5/20*100 =E5/20*100 =F5/20*100 =G5/20*100 =SUM(C5:G5)/H5*100

I JKL

% Cover by

Seeded

Species

% Cover by

Seeded Species

371

When the photo frame is in place and the quadrat has been identifi ed, vegetation greater 

than one inch from the surface of the soil is cut to a height of one inch and removed. The 

tripod is positioned over the photo frame so the camera is approximately on the same plane 

as the ground surface. The camera lens should be adjusted so the photo image in the view 

screen is just inside the quadrat frame. The picture should be taken so shadows from the 

tripod or the photographer are not in the frame. Cloudy days are often ideal due to the lack of 

shadows. Clear days, especially when the plots are in direct sunlight, can be diffi cult because 

of the extreme shadows. The camera fl ash can be used under these conditions to reduce the 

contrasts within the images.

The FHWA and USDA Forest Service have developed a method for evaluating digital 

photographs by adapting a software program for monitoring underwater coral cover. The 

program is called “Monitoring soil cover using CPCe digital photo assessment method” and 

it automates the confi guration of a large group of digital photographs so that they are easy 

to evaluate and record. The program navigates the user to the 20 points on each digitally 

photographed quadrat at the click of a mouse. At each point the user records the observed 

soil cover attribute. The data is summarized and can be taken directly into spreadsheets for 

statistical analysis. 

12.3 SPECIES COVER PROTOCOL

The species cover protocol is used to assess the aerial dominance of seeded species. This 

protocol is used when revegetation standards require that a certain percentage of vegetative 

cover be composed of native species. For example, revegetation objectives that were agreed 

upon during the planning phase state that over 50% of the vegetative cover existing on the site 

two years after construction will be composed of native species that were seeded. Monitoring 

the vegetative cover through this protocol will assess whether this was accomplished. Since 

grass and forb cover changes during the season, the timing of species cover monitoring is 

important. The best time to monitor is during fl owering, typically from mid-May through July, 

because the species are identifi able during this period.

Use of a digital camera is not usually applicable to species cover monitoring because identifying 

species is not always possible in digital photographs. Sampling is therefore accomplished 
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Summary

Figure 12.8 – Species of interest (seeded species) are placed as headings in this spreadsheet 

(cells C3 through G3). In the columns below each species, the presence or absence of the species 

is recorded as a “1” for present or “0” for absent. Fill in cells H4 and I4 with equations shown 

in inset. Copy the remainder of the cells with equations by highlighting cells H4 and I4, then, 

while they are highlighted move the curser to the lower right hand corner of cell I4. When the 

curser turns into a cross, left click the mouse and drag the equations down the page. After the 

spreadsheet is completed, do a test run with the data shown in columns A through G to see if the 

equations in column H and I are correct. Note: Rectilinear study areas will not have the transect 

column fi lled in.

I17 fx SUM(C17:G17)/H17*100

A

1

2

3

QuadratELGLBRCA5FECAERLAERUM

Total

Number

Species

Sown

4

5

6

7

8

9

1

1

1

1

2

2

1

2

3

4

1

2

1

1

0

1

0

0

0

1

1

0

1

1

0

0

1

1

1

1

1

0

1

1

0

1

1

0

1

1

0

1

5

5

5

5

5

5

60

40

80

80

40

80

B CDE F G I

Presence of Plants (1=presence, 0=not present)

Total Number

Species Sown

Percent Seeded

Species Present

in Plot

=COUNT(C4:G4) =SUM(C4:G4)/H4*100

=COUNT(C5:G5) =SUM(C5:G5)/H5*100

H I

% Seeded

Species

Present

in Plot

H

Transect /DispersedUnit

372

with a fi xed frame. This sampling protocol typically requires a botanist to identify species and 

another person to help lay out the plots and record data.

Species cover is quantifi ed at each quadrat based on readings from a 20-point fi xed frame (See 

Section 12.2.1). At each point, the species is recorded on a spreadsheet similar to Figure 12.7. 

More columns can be inserted on the spreadsheet to account for a larger number of species. 

The tendency can be to record all species encountered in a sampling area; however, this is not 

recommended. Instead, we recommend grouping species into such categories as “non-native 

grasses,” or “non-seeded native forbs,” which can be useful for later analysis and reporting.

As with all protocols, the sampling design for laying out transects and quadrats depends on the 

shape of the sampling unit (See Section 12.7), and the number of quadrats to sample depends 

on the variability of the parameter of interest (See Section 12.8). How the data will be analyzed 

will be based on the objectives for monitoring (See Section 12.9). These sections should be 

reviewed before this protocol is used.

12.4 SPECIES PRESENCE PROTOCOL

Determining species cover, as outlined in the previous section, can be time-consuming and 

expensive. The species presence protocol is an alternative method of determining whether 

or not species that were seeded are present on the site. While this method still requires a 

botanist in the fi eld, it takes far less time per plot because only presence or absence of a species 

is recorded.
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Summary

Figure 12.9 – Prior to monitoring, a list of planted species are identifi ed in cells C3 through G3. 

At each plot, the number of plants of each species is recorded in columns C through G. The size 

of the quadrat is recorded in Column H (a 1/100 acre plot is 436 ft2). Using the equations shown 

in the inset for Columns I through N, the number of plants per species per acre is calculated. 

Column N sums the total number of plants per acre as represented in each plot. Fill in cells 

I4 through N4 with the equations, then copy to the remaining cells. Note: There is only one 

quadrat per transect.

H20 fx

A

1

2

3

QuadratPIPOPSMELIDEARMEARPA

Size of

Quadrat

(sq ft)

PIPOPSMELIDEARME

4

5

6

7

8

9

1

2

3

4

5

6

1

2

3

4

5

6

3

4

4

1

3

0

1

3

1

2

1

1

0

2

1

0

0

1

1

0

3

3

0

2

0

1

4

2

2

1

436

436

436

436

436

436

300

400

400

100

300

0

100

300

100

200

100

100

0

200

100

0

0

100

100

0

300

300

0

200

500

999

1,299

799

599

500

B CDE F G I J KL N ARPA 0

100

400

200

200

100

M

Number of Plants per Quadrat Plants per Acre

M N

Plants per Acre

=C3 =D3 =E3 =F3 =G3

=C4*43560/H4 =D4*43560/H4 =E4*43560/H4 =F4*43560/H4 =G4*43560/H4 =SUM(I4:M4)

=C5*43560/H5 =D5*43560/H5 =E5*43560/H5 =F5*43560/H5 =G5*43560/H5 =SUM(I5:M5)

I JKL

Total

Plants

per Acre

Total Plants

per Acre

H

Transect /DispersedUnit

373

In this method, a fi xed frame is placed on the surface of the soil at each quadrat. The size of the 

fi xed frame should be based on what is considered a measurement of success. For instance, 

for shrub or tree species, having one plant established every 10 ft2 (equivalent to 4,356 plants/

acre) would be very successful. However one grass plant every 10 ft2 might not be considered 

successful. For monitoring most species, we recommend a frame size of 4 ft2 (2 ft on each side) 

using a PVC pipe with connectors. This size frame is easy to carry and read. Whatever size is used, 

we recommend that the frame dimension stay the same throughout the monitoring project. 

Prior to sampling, the species of interest (typically just the seeded species) are identifi ed and 

recorded on the data form (Figure 12.8). These will be the only species recorded at each quadrat. 

At each quadrat, the species of interest are evaluated for presence or absence. If the species is 

present, it is given a “1,” and if it is not present, it is given a “0.” The data is summarized by the 

percentage of the species present on the quadrat out of the total number of seeded species.

As with all protocols, the sampling design for laying out transects and quadrats depends on the 

shape of the sampling unit (See Section 12.7), and the number of quadrats to sample depends 

on the variability of the parameter of interest (See Section 12.8). How the data will be analyzed 

will be based on the objectives for monitoring (See Section 12.9). These sections should be 

reviewed before this protocol is used.

12.5 PLANT DENSITY PROTOCOL

Trees and shrubs are typically established from plants (See Section 10.2.6, Nursery Plant 

Production and Section 10.2.3, Collecting Wild Plants) or cuttings (See Section 10.2.2, Collecting 

Wild Cuttings and Section 10.2.5, Nursery Cutting Production). Many constructed wetlands 

are also planted from nursery grown or wild collected seedlings. Monitoring the density of 

live plants following the fi rst and third year after they are planted is important in order to 

determine if they have survived and whether the site will need to be replanted. In the case of 

constructed wetlands, plant density monitoring is conducted to determine whether regulatory 

requirements were met.

The quadrat in this protocol is a circular plot with a specifi ed radius. We recommend using a 

1/100 acre plot, which has an 11.7 ft radius and covers 436 ft2. A staff is placed at plot center 

and a tape or rope is stretched 11.7 ft. While one person holds the staff , the other walks the 
Roadside

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Figure 12.10 – A spreadsheet is shown here for recording one species and one attribute. This 

spreadsheet can be developed to record several attributes or several species.

K4 fx

A

1

2

3

QuadratPlant 1Plant 4Plant 5

Average

4

5

6

7

8

1

2

3

4

5

32

36

35

30

27

33

32

36

39

41

27

25

31

39

25

Plant 2Plant 3

41

29

33

34

25

34

25

33

32

33

33

29

34

35

30

B E C D F G

Attribute: Plant Height (in)

Species: PIPO

G

=AVERAGE(B4:F4)

=AVERAGE(B5:F5) Average

374

circumference of the plot and counts the number of plants within the quadrat. This information 

is recorded on a spreadsheet similar to Figure 12.9. This spreadsheet reports the number of 

plants per acre by species. It also summarizes total plants per acre.

From this spreadsheet plant density can be estimated and an approximate survival rate can be 

determined by dividing the estimated density (average of column N) by the original planting 

density (per acre basis from planting records). Plant density monitoring used to determine 

survival rates are called survival surveys and these are usually conducted in the fall or winter. If 

the site is planted in the fall or spring and monitoring occurs the following fall, the results are 

referred to as the “fi rst year survival.” Plant density monitoring thereafter, is referred to as the 

years after planting (e.g., third year sampling is “third year survival”).

The sampling design for laying out transects and quadrats depends on the shape of the 

sampling unit (See Section 12.7), and the number of quadrats to collect from depends on 

the variability of the parameter of interest as discussed in Section 12.8. (Note that for linear 

sampling designs, there is only one randomly placed quadrat per transect.) How the data will 

be analyzed will be based on the objectives for monitoring (See Section 12.9). These sections 

should be reviewed before this protocol is used.

12.6 PLANT ATTRIBUTES PROTOCOL

The plant attributes protocol is used to measure plant growth. This protocol can be used to assess 

growth responses between revegetation treatments or revegetation units, and to determine 

whether standards pertaining to growth requirements were met. Typically only sensitive areas, 

such as visual corridors or wetlands, have stated growth requirements that must be monitored. 

This protocol might have limited applicability to most revegetation projects.

Any part of a plant can be measured, and the selection of an attribute is dependent on the 

species being sampled. Common attributes include:

 · Total height – trees and most shrubs

 · Last season’s leader length – most trees

 · Stem diameter – shrubs and trees

 · Crown cover – shrubs, forbs, and grasses

 · Weight – grasses and forbs

Total height is typically measured from the ground surface to the top of the bud. If the plant 

has several leaders (or tops), the most dominant leader is used for measurement. Last season’s 

leader growth can be observed in most tree species. For conifers, leader growth is measured 
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Summary

375

from the last whirl of branches to the base of the bud. Comparing leader growth from year to 

year can indicate whether plants are healthy and actively growing. Stem diameter can be used 

to measure most trees and shrubs; in this method, the basal portion of the plant is measured 

with calipers at the ground surface. Crown cover is more conducive to spreading plants, such 

as shrubs, grasses, and forbs. This measurement requires the use of a large frame with grids 

or points that can be placed over the plant to obtain an aerial coverage. Weight of the plant is 

typically used for grasses and forbs. Foliage is clipped at the base and weighed immediately for 

fresh weight, or dry weight after the sample has been oven-dried.

Sampling plant attributes should be narrowed to a species of interest. It is probably not 

necessary to measure all species on a site. Those species that are easy to measure and will 

dominate the site are the best to sample (typically trees and shrubs). It is not necessary to 

sample all plants in a quadrat. We suggest a minimum sample of 5 plants from each species. 

An unbiased way to select which plants of each species to monitor is to sample those plants 

closest to plot center. If there are not enough plants in the quadrat to sample, then the nearest 

plants outside of the quadrat should be sampled. 

The measurement for each plant is recorded in a data sheet similar to Figure 12.10. The species 

and the attribute being measured must be identifi ed on each sheet (cell B2). The number of 

quadrats to establish depends on the variability of the plant attribute which is discussed in 

Section 12.8. How the data will be analyzed is based on the objectives for monitoring (See 

Section 12.9). These sections should be reviewed before this protocol is used.

12.7 SAMPLING AREA DESIGN

Three basic sampling designs are used to monitor revegetation units depending on the shape 

or geometry of the sampling areas. The primary objective of these designs is to provide even 

spatial coverage of sampling locations within revegetation units that results in unbiased data 

collection. The three types of designs that will be covered are:

Linear (See Section 12.7.1). Long and narrow sampling areas, such as road cut and fi ll slopes, 

are sampled using a systematic series of transects, oriented perpendicular to the road, along 

which are located a set of quadrats. Each transect is treated as the primary experimental unit 

for statistical analysis.

Rectilinear (See Section 12.7.2). For more rectilinear sampling areas, a systematic grid (that is, a 

checkerboard) of quadrats is sampled, and each quadrat is treated as the primary experimental 

unit for statistical analysis. 

Dispersed (See Section 12.7.3). When a series of discrete areas (e.g., planting pockets, 

planting islands) are encountered, a systematic or grid sample design of dispersed areas is 

identifi ed for sampling. Depending on the geometry and size of these areas, either complete 

enumeration (measuring all plants) or subsampling using transects or grids is employed within 

selected areas.

12.7.1 Linear Sampling Areas

Linear areas, such as cut and fi ll slopes and abandoned roads, are sampled using a systematic 

series of equally spaced transects. Each transect has varying numbers of quadrats (plots), 

depending on the length of the transect. When the revegetation unit is fairly uniform in width, 

each transect will have approximately an equal number of quadrats; when the width of the 

revegetation unit is highly variable, there will be unequal numbers of quadrats per transect. In 

either case, each transect is treated as the primary experimental unit.

Figure 12.11 shows a typical sampling design for a linear area. In this example, the sampling area 

included only those portions of the cut slope that were seeded; it did not include road shoulders 

or ditch line. For statistical analysis, the number of transects (n) to collect was estimated to be 

20 based on pre-monitoring data (See Section 12.8). Spacing the 20 transects equally along the 

sampling area was calculated by dividing the total length of the sampling area by the number 

of transects to obtain the distance between transects (3,100/20 = 155 ft). Locating the fi rst 

transect was done in an unbiased way by generating a random number between 1 and 155 

using the random number spreadsheet function shown in Figure 12.12.

Transects are laid out by establishing a line perpendicular to the edge of the road. The 

transect begins at the edge of where seeding or other treatments were completed, which 
Roadside

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Introduction

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Summary

Figure 12.11 – Linear sampling areas are typically long units with varying widths. Road cuts, 

fi lls and abandoned roads typically fi t this sampling design. The design of linear sampling areas 

uses a series of transects with uniformly spaced quadrats within each transect. The distance 

between quadrats varies by the length of the transect. Transects longer than 100 feet have 20 

feet of spacing between quadrats (T4 through T6), transects between 20 and 100 feet have 10 

feet between quadrats (T9 through T14), and transects less than 20 feet long have two randomly 

placed quadrats (T15 through T20).

Transect length is:

>100 ft

Revegetation Unit

Road Shoulder – Not Sampled

Road

Transect and Quadrat

Transect length is:

>20 ft

Transect length is:

>20 ft but <100 ft

T3

T4

T5 T6

T6

T7

Not a Transect Sampling Area

Width

T8

T9 T10 T11 T12

T13

T14

T15

T16

T17

G F G

E

T10

T17

T18

T19 

T20

B

T2

T1

A

C = 155’

D = 23’

20’

10’

Top of Cut Slope

A = Starting point

B = Ending point

A to B = Length (L) of sampling area (3,100 ft)

n = Number of transects (20) calculated from pre-monitoring data (Section 12.8)

C = Distance between transects = length (L) / number (n) of transects = 3,100/20 = 155 ft

D = Distance to first transect = random number within the distance between transects (between 1 and 155 ft)

E = For >100 ft transect, a random number between 1 and 20

F = For >20 ft but <100 ft transect, a random number between 1 and 10

G = for <20 ft transect, two random numbers between 1 and 19 376

is typically beyond the road shoulder and ditch. Each transect contains a group of evenly 

spaced quadrats.

The spacing between quadrats vary by the length of the transect:

 · <20 ft transect lengths. For sampling areas where transect lengths are less than 20 feet, 

2 quadrats are installed. Two random numbers (G) are generated between the numbers 

1 and 19. These numbers indicate the location of each transect.

 · >20 and <100 ft transect lengths. For sampling areas where transect lengths are 

between 20 and 100 feet, quadrats are placed at 10 foot intervals. The distance to the 

fi rst quadrat will be based on a random number between 1 and 10 feet.

 · >100 ft transect lengths. These long transects have 20 feet between quadrats. The 

distance to the fi rst quadrat will be based on a random number between 1 and 

20 feet.

For the Plant Density and Plant Attribute protocols, only one quadrat is randomly located within 

each transect. The location is determined by assigning the RANDBETWEEN random number 

function to the length of each transect (Figure 12.12).
Roadside

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Summary

Figure 12.12 – The locations for the fi rst 

quadrat for each transect are based on 

randomly assigned numbers that can be 

obtained prior to going to the fi eld using 

the RANDBETWEEN function. This tool 

provides uniformly distributed random 

numbers within a specifi ed range. 

For example, if the distance between 

quadrats has been calculated to be 52 ft, 

then random numbers between 0 and 

52 feet can be calculated by providing 

the following equation for each transect: 

“=RANDBETWEEN(0,52).” The number 

given for each transect is the distance 

from the edge of the revegetation unit to 

the fi rst quadrat.

16

P10

A C B D

3

4

5

6

7

8

9

10

11

12

13

14

15

T2

T1

43

32

24

28

17

2

38

40

44

18

Transect ID Random Start

T3

T10

T11

T8

T9

T7

T6

T5

T4

1

=RANDBETWEEN (0,52)

SUM fx

Sheet 1

2

377

12.7.2 Rectilinear Sampling Areas

When sampling areas are more elliptical or rectangular in shape, or composed of several 

large irregular polygons, the sampling design will be based on a rectangular grid of quadrats 

systematically located with a random starting point. Figure 12.13 shows an example of such 

a sampling design. Notice that this design is diff erent from the linear sampling design in that 

there are no transects. The quadrat in this sampling design is the primary experimental unit, 

not the transect.

To determine the grid spacing (E) for the quadrat locations, the area of the sampling unit must 

be obtained from maps, and the number of quadrats to be sampled (n) must be determined 

from pre-monitoring data (See Section 12.8.2). The following equation gives the length of each 

side of a square grid (E):

Area E = n

For example, the sampling area in Figure 12.13 covers 4,262 ft2 and it has been determined 

from pre-monitoring data that approximately 20 quadrats are necessary to attain the statistical 

sampling requirements for this sampling area. The formula indicates that each side (E) of the 

grid should be 14.6 ft:

E = 4,262 / 20 = 14.6 ft

A starting point of the grid is arbitrarily located in any corner of the study area. To avoid biasing 

the placement of the quadrats, the corner of the grid must be shifted by assigning random 

numbers to the x and the y coordinates as shown in Figure 12.13. This is called a systematic design 

with a random start. It provides equal likelihood that any point in the study area is included in the 

sample unless there are obvious systematic patterns in the site such as planting rows. In this case, 

the random number shifts were 11 ft in the horizontal direction and 4 ft in the vertical direction.

In this example, the monitoring team would locate the starting point in the fi eld. Taking a true 

north bearing, the team would measure 39.8 ft (10.6+14.6+14.6 = 39.8) to take the fi rst plot. They 

would measure 14.6 ft on that bearing to locate the next quadrat. After they collected data 

from the last quadrat in that line, they would take a due east bearing and walk 14.6 ft to locate 

the next plot. This system of sampling would continue until the entire area has been sampled.
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Figure 12.13 – For rectangular or elliptical sampling areas, a grid composed of quadrats is used. 

The length of the grid cells (E) is calculated , which becomes the standard distance between 

quadrats for this sampling area. To avoid bias, the x and y axis of the grid is randomly off set. The 

monitoring team follows compass bearings and uses a measuring tape in a systematic manner 

to locate all quadrats.

Random Shift in

Y Direction (4 ft)

Random Shift in

X Direction (11 ft)

Sampling Area

Starting Point

Grid Corner

Quadrant Location

Direction of Travel

N

w e

A

E

E

First Quadrat

14.6 ft

39.8 ft

378

12.7.3 Dispersed Area Sampling

When sampling areas occur as small, distinct areas, a two-stage sampling design is recommended. 

The fi rst stage is to determine which dispersed areas to sample and the second stage is 

determining how to sample within each selected area. For the fi rst sampling stage we suggest 

that a minimum of 20 dispersed areas be monitored within each revegetation unit. If there are 

20 dispersed areas or fewer, then all dispersed areas would be sampled. If there are more areas 

than 20, then they must be sampled using one of two sampling designs. For dispersed areas that 

range in sizes from small to large and are mapped, the systematic sampling design is used (See 

Section 12.7.3.1). If the dispersed areas are small or are not mapped, then a grid sampling design 

is used (See Section 12.7.3.2). In most cases, the grid sampling method is recommended. 

12.7.3.1 Systematic Sampling of Dispersed Areas

First Stage – The systematic sampling method of dispersed areas assumes that the dispersed 

areas have been mapped and identifi ed. The dispersed area in this method is the experimental 

unit. In this approach, the dispersed areas are numbered sequentially by progressing from one 

dispersed area to the next closest dispersed area. Determining how to calculate the number (n) 

of dispersed areas to sample is presented in 12.8.3. Odd- or even-numbered dispersed areas are 

selected based on a random number using the RANDBETWEEN function. For example, if there 

were 40 dispersed areas (N) but only 20 dispersed areas needed to be sampled (n), then 50% 

of the dispersed areas would be sampled (n/N). A random number using RANDBETWEEN(1,2) is 
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Random Shift in

X Direction

Random Shift in

Y Direction

PS1 Layout Units to Sample

Direction of Travel

Starting Point

First Quadrat

Quadrats to Sample

E

E

PS1

PS2

PS3

PS4

PS5

PS6

PS7

PS8

PS9

PS10

N

w e

Figure 12.14 – A systematic sample of dispersed areas, shown in this example, is based on 50% 

sampling (the pink areas). Alternating dispersed areas were sampled. Quadrats were located 

in each sampling area by fi rst locating a starting point and then measuring off random x and y 

off set coordinates to locate the fi rst quadrat of the sampling grid.

379

used. If the function returns a “1” the odd numbered dispersed areas are selected; if 2, then even 

numbered areas are selected. Figure 12.14 provides a schematic depiction of such a design.

Second Stage – Once the dispersed areas have been selected, the layout of quadrats within 

each dispersed area is determined. A grid-based sampling design, as described in Section 

12.7.2, can be used. To determine the grid spacing (E) for the quadrat locations, determine 

whether the size of the dispersed area is >1,600 ft2 or <1,600 ft2 (1,600 ft2 is a 40 by 40 ft area). 

Depending on the sample size, the number of quadrats will be:

 · Less than 1,600 ft – 4 quadrats

 · Greater than 1,600 ft – 8 quadrats

Using the following equation, the grid sides (E) are determined where n = 4 or 8 depending on 

the size of the dispersed area and Area is the estimated dispersed area size.

Area E = n
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This calculation will be made for each dispersed area. To avoid biasing the placement of 

quadrats, a predetermined starting point is decided upon (e.g., the northwest corner of each 

dispersed area). Random x and y coordinates are generated for each dispersed area that are 

within the predetermined length of the square grid (E). The corner of the grid is placed at this 

point and oriented north. The location of the fi rst quadrat is x and y coordinates from the 

starting point as shown in Figure 12.14.

For the plant density and plant attribute protocols, only one quadrat is randomly located within 

each dispersed sampling area. The location is determined by assigning the RANDBETWEEN 

random number function to the number of quadrats determined for the dispersed area. The 

random number that is generated is the quadrat selected for sampling.

12.7.3.2 Grid Sampling of Dispersed Areas

First Stage – A grid sampling design is used on projects where dispersed areas have not been 

mapped and there are more than 30 areas. This sampling design is typically used on projects 

where dispersed areas are numerous and the sizes of the areas are small. In this sampling 

design a grid is placed over the revegetation unit as shown in Figure 12.15 and the dispersed 

area nearest to the grid center is selected for monitoring. One quadrat is randomly placed in 

each dispersed area and this becomes the experimental unit.

Determining the grid cell dimensions (E) is accomplished by using the following equation:

Area E = n

where the area is the total area of the revegetation unit and n is the number of quadrats to 

locate (See Section 12.8.3 for determining number of quadrats to sample).

The grid is laid out unbiasedly by locating a starting point just outside the revegetation unit 

and assigning random numbers to the x and the y coordinates. The corner of the grid is placed 

at the x and y off set point and oriented north. In the fi eld the grid centers are located using a 

compass and measuring tape. At each grid center, the closest dispersed area is selected for 

monitoring. If there are no dispersed areas found within half the distance between grid centers 

(E/2), then the monitoring team moves on to the next grid center. For revegetation units that 

have dispersed areas somewhat clustered, grid centers will sometimes be located where there 

will be no dispersed areas to sample. For this reason, when calculating the grid cell dimension 

(E) from the equation above, the number of quadrats (n) should be increased 10 to 20% to 

compensate for grid centers where dispersed areas are not in close proximity. 

Second Stage – For seedling density and seedling attribute protocols, dispersed units that are 

selected for sampling may be small enough that plant measurements can be exhaustive (e.g., 

all plants are measured). These situations usually arise when seedlings are planted in planting 

islands, benches, or pockets. When this is not possible, or other protocols, such as soil cover, 

species cover, or species presence protocols are being used, one quadrat is located randomly 

by facing away from the dispersed area and throwing a rock, hammer, or something heavy and 

selecting the quadrat location where it lands.

12.8 SAMPLE SIZE DETERMINATION

The number of experimental units needed to statistically sample a revegetation area is based 

on the variability of the attributes being sampled. By pre-sampling representative areas prior 

to monitoring, an approximate number of quadrats and transects can be determined. Using 

pre-monitoring data, however, does not always guarantee enough samples will be taken. There 

will be projects where pre-monitoring data will not predict the variability, and more samples 

will be needed. This is usually discovered after reviewing the data back at the offi ce. At that 

time, the monitoring leader has to decide whether to return to the site and collect more data. 

To avoid this expensive scenario, we recommend that each revegetation unit be composed of 

at least 20 primary experimental units (20 transects for linear sampling design, 20 quadrats for 

rectilinear, or 20 dispersed areas for dispersed area sampling design).

Taking a minimum of 20 samples should help prevent the possibility of having to return to the 

site to collect more data. The cost of collecting a small amount of extra data from quadrats or 

transects during initial monitoring is typically low relative to the cost of personnel, equipment, 

and travel to and from the project area. Taking a minimum of 20 samples is considered a prudent 
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Figure 12.15 – Small dispersed areas can be randomly sampled using a grid that is off set in the 

x and y axis. The grid dimensions (E) are calculated based on number of grid centers (n) needed 

and the size of the revegetation unit. Once grid centers are located, the nearest dispersed unit 

is found (closest dispersed unit is shown in circle). If there are no dispersed units within half the 

distance between grid centers (E/2), then the monitoring team moves to the next grid center.

E

E

Random Shift in

Y Direction

Random Shift in

X Direction

N

w e

Revegetation Unit

Starting Point

Grid Center Point

Dispersed Unit

Dispersed unit closest to grid

center point to sample

381

precaution. While 20 samples should be enough for most projects, sample size calculations 

should nevertheless be conducted to determine whether additional primary experimental 

units may be needed to achieve the precision requirements of the monitoring plan.

Sample size determination methods must be tailored to the monitoring objectives and 

sampling area design. For compliance objectives for linear area sampling design see Section 

12.8.1, rectilinear sampling area design see Section 12.8.2, and dispersed areas see Section 

12.8.3. For determining sample size for comparing treatments areas see Section 12.8.4

12.8.1 Comparing Means with Standards – Linear Sample Size Determination

To calculate the minimum sample size for linear sampling areas (See Section 12.7.1), it is 

necessary to approximate the expected sample mean and the range in values. A visual 

estimate of the mean and the range of values may be adequate. However, for more precise 

estimates, 4 transects can be sampled to establish estimates of the mean and range of values. 
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Figure 12.16 – Example of how to 

calculate the number of transects needed 

to be established from pre-monitoring 

data set.

Quadrat

Transect Q1 Q2 Averages

T1 10 15 12.5

T2 12 22 17

T3 18 6 12

T4 32 21 26.5

Estimated Mean = 17

Range (26.5 - 12.5) = 14.5

n = (0.838 * 14.5)

2 / (0.2 * 17.0)2

 = 12.8 transects 382

The following is a quick method of determining the number of transects to sample based on 

pre-monitoring data collection:

1) Drive the entire revegetation unit and note the diff erent extremes of revegetation success. 

2) Find 4 areas that represent the extremes and lay out a transect in each area.

3) Randomly place 2 quadrats within each transect to collect data on the attribute of 

interest (e.g., % ground cover). 

4) For each transect, average the quadrat values (4 averages).

5) Calculate the average of the 4 transect averages and calculate the range (diff erence 

between highest and lowest values of the 4 averages).

6) Apply the range and the average to the following equation to obtain the minimum 

number of transects needed to monitor the revegetation unit (equation based on a 

sample size of 20% of the true population value with 90% confi dence).

n = (0.838 * Range)2 / (0.2 * x)2

The number of transects (n) obtained from this quick assessment is used to determine the 

layout of the monitoring design as discussed in Section 12.7.

Example: Suppose that monitoring is to be conducted along a road cut to determine the 

percentage of soil cover. The monitoring objective is to estimate mean percent cover to within 

20% of the true population value with 90% confi dence. Four transects that represent a range in 

conditions are laid out within the revegetation unit. These transects do not need to be located 

randomly, but rather should be sited to capture the range of values observed in the sampling 

area. It is better to over-estimate the range of values, as this will tend to result in a conservative 

estimate of the sample size. The data set and equation is shown in Figure 12.16.

Using the equation presented above, an estimated 13 transects were calculated for a minimum 

sample size. Although the minimum sample size is estimated at 13, it is still recommended 

that at least 20 transects be sampled because the cost of additional transects (should the 

actual monitoring data be more variable than the pre-monitoring data) is minor relative to the 

expense of returning to the site and collecting more data.

12.8.2 Comparing Means with Standards –Rectilinear Sample Size Determination

When a grid of quadrats is to be implemented (See Section 12.7.2), the sample size calculations 

use quadrat measurements as opposed to the transect averages that were used in linear 

sampling areas. The steps involved in calculating the number (n) of quadrats are:

1) Visit the entire revegetation unit and notice the diff erent extremes of revegetation success. 

2) Find 4 areas that represent these extremes and lay out a transect in each area.

3) Randomly place 2 to 3 quadrats within each transect to collect data on the variable of 

interest (e.g., % ground cover).

4) Average the quadrat values (8 quadrat values to average) 

5) Calculate the range of all 8 samples (diff erence between highest and lowest values).
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6) Apply the range and the average to the following equation to obtain the minimum 

number (n) of transects needed to monitor the revegetation unit.

n = (0.838 * Range)2 / (0.2 * x)2

Using the data from the previous example (Figure 12.16), the 8 quadrats would be averaged. 

While the mean in this example would still remain at 17, the range has spread to 26 (maximum 

32 minus the minimum 6) The number of quadrats to sample would be 41:

n = (0.838 * 26)2 / (0.2 * 17.0)2 = 41.1

12.8.3 Comparing Means with Standards – Dispersed Area Sample Size Determination

Systematic Sampling Method: The systematic sampling method is used when the dispersed 

areas are mapped. The experimental unit in this design is the dispersed area.

1) Find 4 dispersed areas that represent the extremes of the attribute of interest and lay out.

2) Randomly place 2 quadrats within each dispersed area to collect data on the attribute 

of interest (e.g., % ground cover).

3) For each dispersed area, calculate the average of the 4 dispersed areas’ averages and 

the range.

4) Apply the range and the average to the following equation to obtain the minimum 

number of dispersed areas needed to monitor in a revegetation unit (equation based 

on a sample size of 20% of the true population value with 90% confi dence).

n = (0.838 * Range)2 / (0.2 * x)2

Grid Sampling Method: The grid sampling method is used for revegetation units that have 

small dispersed areas that have not been mapped (See Section 12.7.3.2). Since only one quadrat 

is located in a dispersed area, the quadrat becomes the experimental unit. The number of 

quadrats to sample is estimated by following these steps:

1) Visit a range of dispersed areas and select 4 dispersed areas that represent these 

extremes of site conditions.

2) Randomly place 1 quadrat in each of the 4 dispersed areas and collect data on the 

parameter of interest (e.g., % ground cover).

3) Calculate the average and range in values.

4) Apply the range and the average to the following equation to obtain the minimum 

number (n) of dispersed areas to sample.

n = (0.838 * Range)2 / (0.2 * x)2

12.8.4 Sample Size for Comparing Means Among Treatment Groups

When determining the sample size for comparing treatment diff erences (See Section 12.9.2), 

it is not necessary to diff erentiate between linear, rectilinear, or dispersed sampling designs. 

Sample size determinations can be made by following these steps:

1) Review each treatment area to be compared. These can be diff erent revegetation units 

or diff erent types of revegetation treatments.

2) From each treatment area, collect data from 2 transects composed of 2 quadrats. These 

should represent a range of extremes for a total of 4 transects.

3) Determine the range.

4) Determine delta. Delta defi nes the level of signifi cance that is needed for monitoring, 

or the meaningful diff erence in measurement output. For example, calculating bare soil 

at 1% diff erences in means would be unimportant, that is, the diff erence between 8% 

and 9% bare soil is too fi ne a distinction to make. A 5% diff erence might be important 

if the amount of data that is needed to be collected was not great. More than likely, 

a 10% diff erence (e.g., the diff erence between 10% and 20% bare soil) would be an 
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384

acceptable delta value for bare soil cover. It is important to note, the smaller the delta 

value, the more samples need to be collected.

The number of transects (n) can be calculated using a simplifi ed equation:

n = 15.68 / (∆ * 2.059 / Range)2

The number of transects determined from these calculations are applied equally to the two 

(or more) areas being compared. This equation assumes that tests will be conducted at the 

delta level of signifi cance and that there will be a diff erence detected at or greater than an 

80% probability. Readers who prefer to apply diff erent assumptions are encouraged to read 

the backup document to this guide (Kern 2007).

Example: Suppose you are interested in fi nding out whether a commercial product actually 

increases plant cover by at least 10% after the fi rst year as advertised. You have set up similar 

areas, one where the product was applied and one where it was not. A year later, you want 

to determine whether there is a diff erence in the percentage of vegetative ground cover. To 

determine the number of transects to install in each area, you set out 4 transects, 2 in each area. 

From this information, you fi nd a range in % vegetative ground cover values of 22. You assume 

that tests will be conducted at the delta level of signifi cance of 10% (important to be able to 

detect a diff erence in 10% cover with at least 80% probability). Using the simplifi ed equation 

stated above, the following number of transects are required for each treatment area:

n = 15.68 / (10* 2.059 / 22)2 = 17.9 transects

In general, using the simple equation provided here, and possibly adding 10% to 20% additional 

samples as a level of conservatism, is a reasonable approach.

12.9 STATISTICAL ANALYSIS USING CONFIDENCE INTERVALS

This section provides statistical methods for analyzing data collected for all monitoring 

protocols covered in this chapter. There are three types of analysis based on these 

monitoring objectives:

 · Compliance – determine whether standards were met (See Section 12.9.1).

 · Treatment differences – determine whether there is a diff erence between treatments or 

changes between years (See Section 12.9.2).

 · Trends – determine the degree of vegetation or soil cover change over time (See 

Section 12.9.3).

The analysis for these objectives uses the concept of confi dence intervals for determining the 

statistical signifi cance of the monitoring data set.

12.9.1 Determine Standards Compliance

The objective behind most monitoring is to answer the following questions: were 

regulatory standards met? Did we actually do what we stated we were going to do in our 

reports and commitments to the community in terms of protecting soil and reestablishing 

native vegetation?

To answer these questions requires comparing the means of the attribute data collected (e.g., 

bare soil, species presence) with the set standard or stated threshold. For example, a project 

has a standard of at least 70% soil cover on a road cut near a live stream one year after road 

construction. Using the soil cover protocol, data is collected on 20 transects and a mean of 

81% soil cover is determined by averaging the quadrat means. At this point, the reader might 

conclude that the standards were met. From a statistician’s point of view however, the data 

displayed in this context is inconclusive because we do not know, or cannot account for, the 

variability of the soil cover in the sampling area. In other words, how do we know how good the 

number is? Is it really depicting what is happening on the site? If another person were to use the 

soil cover protocol in the same sampling area, but at a diff erent spot, would the soil cover be 

exactly 81%? This is highly unlikely because of the high variability of soil cover.

Confi dence intervals give us the means of predicting, at a chosen level of certainty, that the soil 

cover value collected anywhere in the sampling area will be within a stated range. Confi dence 

intervals are an alternative to saying, “We think the soil cover at any point in the sampling area 
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Figure 12.17 – Data set A has an 

upper confi dence limit of 89% and a 

lower confi dence limit of 73%. Since 

the lower confi dence limit is above the 

standard of 70%, it can be stated with 

90% confi dence that the standards were 

met. Data set B has a wider confi dence 

interval and a lower confi dence limit 

of 66%, which is below the standard. 

In this case, there is uncertainty at the 

90% confi dence limit that the standards 

were met.

60%

Unacceptable

Acceptable

Threshold

90%

100%

70%

80% A B

LCL = 66%

89%

73%

UCL = 96%

x = 81%

Upper Confidence Limit

Lower Confidence Limit

UCL

LCL

385

will be around 81%.” Using confi dence intervals we can say instead that, “we are 90% confi dent 

that if the study were repeated at this site 10 times, 9 out of 10 times the average soil cover 

estimate would be within our confi dence limits.” If you want to feel more confi dent than that 

about your predictions (most scientists working in the health fi elds want to be very certain) you 

might decide you want to have confi dence intervals based on 95% or even 99% certainty. If this 

is the case, the confi dence interval would be much wider.

The data sets from very diff erent revegetation units are shown in Figure 12.17 to convey the 

concept of confi dence intervals. While both data sets have the same mean of 81% soil cover, 

the confi dence intervals are very diff erent. Data set A was taken at a site with very uniform soil 

cover, while data set B had much more variability. For both data sets, we want to defi ne the 

confi dence intervals at a 90% confi dence. Notice that the confi dence interval for data set B is 

much wider than data set A since it has greater variability.

With confi dence intervals, we can say with greater certainty whether the standard of 70% soil 

cover was met or not. We can state with 90% confi dence that data set A met the standards 

because the lower confi dence limit (73%) is above the stated standard of 70%. Data set B, 

on the other hand, poses some problems. We cannot say with 90% confi dence that the unit 

average is above the standard of 70%. The lower confi dence limit of data set B is 66%, or 4% 

below the standard. The reader might argue that, because the mean is above the standard, the 

standards were met (“hey, it’s close enough!”). To statisticians, however, the fact that the lower 

confi dence interval is below the stated standards indicates a fair amount of uncertainty. They 

would tell you that you cannot make that statement without getting more data or changing 

how confi dent you are with the prediction.

One of the main purposes for monitoring roadside vegetation is to document successful 

project completion. Statistically based sampling designs and analysis provides an objective 

way to describe revegetation performance. An understanding of confi dence limits and their 

interpretation is critical to documenting that standards have been met. The following section 

outlines how confi dence intervals are calculated and compared with standards. It is organized 

by sampling design: linear, rectilinear, and dispersed.
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Figure 12.18 – Confi dence intervals for linear sampling designs can be easily obtained by 

copying equations and format of this spreadsheet.

A1

A C B I DEFG H J K

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

28

29

30

31

32

33

34

35

36

37

38

T2

T1 = AVERAGE(C4:H4)

= AVERAGE(C5:H5)

= AVERAGE(C6:H6)

= AVERAGE(C7:H7)

= AVERAGE(C8:H8)

= AVERAGE(C9:H9)

= AVERAGE(C10:H10)

= AVERAGE(C11:H11)

= AVERAGE(C12:H12)

= AVERAGE(C13:H13)

= AVERAGE(C14:H14)

= AVERAGE(C15:H15)

= AVERAGE(C16:H16)

= AVERAGE(C17:H17)

= AVERAGE(C18:H18)

= AVERAGE(C19:H19)

= AVERAGE(C20:H20)

= AVERAGE(C21:H21)

= AVERAGE(C22:H22)

= AVERAGE(C23:H23)

= B4*14

= B5*15

= B6*16

= B7*17

= B8*18

= B9*19

= B10*110

= B11*111

= B12*112

= B13*113

= B14*114

= B15*115

= B16*116

= B17*117

= B18*118

= B19*119

= B20*120

= B21*121

= B22*122

= B23*123

= B4^2

= B5^2

= B6^2

= B7^2

= B8^2

= B9^2

= B10^2

= B11^2

= B12^2

= B13^2

= B14^2

= B15^2

= B16^2

= B17^2

= B18^2

= B19^2

= B20^2

= B21^2

= B22^2

= B23^2

Q1 Q2 Q3 Q4 Q5 Q6 Average

Transect

ID

Transect

Length

Parameter: Calculations

T3

T13

T10

T11

T12

T15

T16

T20

T19

T18

T17

T14

T8

T9

T7

T6

T5

T4

fx

1

L1 x x1 L1

2

Field Data

= Sum (J4:J23) = Sum (K4:K23)

27

Equations

= SUM(B4:B23) 

= J24/E27 

= VAR(I4:I23) 

= K24/E27/E27*VAR(I4:I23) 

= SQRT(E30) 

= COUNT(I4:I23)-1 

= TINV(0.1,E32) 

 

= E28-E33*E31 

= E28+E33*E31

Mean

Between Transect Variance

Variance of Mean

Standard Error

Degrees of Freedom

T

 

90% Lower Confidence Limit:

90% Upper Confidence Limit:

386

12.9.1.1 Calculating Confi dence Intervals for Linear Sampling Design

Figures 12.18 and 12.19 give examples of how to calculate confi dence intervals from a data 

set for a linear sampling area (See Section 12.7.1). Figure 12.18 shows how to set up the 

spreadsheet and Figure 12.19 shows what a typical data set might look like. Once you have set 

the spreadsheet up exactly as it is shown in Figure 12.18, it needs to be tested by entering the 

data shown in Figure 12.19. If the confi dence intervals in your spreadsheet do not match those 

of Figure 12.19, then you will need to review the spreadsheet for errors in copying. Make sure 

that the equations are in the same cells as shown in Figure 12.18. To obtain a number for “T” (cell 

E31) the Excel ToolPak must be installed. To do this, go to the toolbar and select Tools, Add-Ins, 

and check the box next to Analysis ToolPak.

The essential data needed to complete the spreadsheet in Figure 12.18 is:

Transect Length (Column B) – This is the total length of the transect recorded in the fi eld at the 

time the transect is laid out.

Parameters (Cell C2) – There may be several parameters collected at each quadrat. The 

parameter (or attribute) to be evaluated should be stated at the top of the quadrat columns. 

For instance, in Figure 12.19, the attribute to be analyzed is “% bare soil,” which was obtained 

using the Soil Cover Protocol spreadsheet (Figure 12.4). Only one attribute can be measured 

on a spreadsheet. Gravel, rock, live and dead vegetation, for instance, are often collected in 

the soil cover protocol. If a statistical analysis of these attributes is needed, a spreadsheet must 

be developed for each attribute. While not all attributes need to be statistically analyzed, it is 

important to analyze those attributes that have been identifi ed for measurements of success 

(e.g., % bare soil or % soil cover).
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Figure 12.19 – The spreadsheet developed from Figure 12.18 can be checked for accuracy by 

entering the data in this spreadsheet.

P10

A C DE F H B IJ K

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

T2

T1 25.0

35.0

28.0

25.0

16.3

36.8

28.7

26.7

20.0

30.0

30.0

38

98

261

100

207

207

150

154

131

131

84

25.0

30.0

20.0

30.0

10.0

50.0

21.0

40.0

10.0

20.0

40.0

10.0

20.0

30.0

22.0

54.0

30.0

40.0

10.0

40.0

50.0 20.0

15.0

35.0

11.0

10.0

30.0

40.0

30.0

950.00

3430.00

7308.00

2500.00

3363.75

7607.25

4300.00

4106.67

2620.00

3930.00

2520.00

1444

9604

68121

10000

42849

42849

22500

23716

17161

17161

7056

0

0

0

0

0

0

0

0

0

Q1 Q2 Q3 Q4 Q5 Q6 Average

Erase these formulas 

if transects 

were not taken

Transect

ID

Transect

Length

Parameter: % bare soil Calculations

T3

T13

T10

T11

T12

T15

T16

T20

T19

T18

T17

T14

T8

T9

T7

T6

T5

T4

fx

1

L1 x x1 L1

2

G

42635.67 262461

Equations

= 1561

= 27.31

= 35.18068182 

= 3.7893 

= 1.9466 

= 10

= 1.8125 

 

= 23.8

= 30.8

Mean

Between Transect Variance

Variance of Mean

Standard Error

Degrees of Freedom

T

 

90% Lower Confidence Limit

90% Upper Confidence Limit

387

Field Data (Columns C Through H) – The data collected at each transect and quadrat for the 

parameter of interest is typed into these cells. This information comes from the spreadsheets 

developed for each protocol (Soil Cover Protocol – Figure 12.4, Species Cover Protocol – 

Figure 12.7, Species Presence Protocol – Figure 12.8, Plant Density Protocol – Figure 12.9, and 

Plant Attributes Protocol – Figure 12.20) and it is entered and summarized by transect.

Columns I and J – If fewer than 20 transects were taken, the equations in the cells of column I 

and J that do not have data must be cleared for the spreadsheet to work (see highlighted cells 

in Figure 12.19).

12.9.1.2 Calculating Confi dence Intervals for Rectilinear Sampling Designs

Figure 12.20 shows how to calculate confi dence intervals for rectilinear sampling areas 

(See Section 12.7.2). Copy the equations exactly as they are shown in Figure 12.20 into your 

spreadsheet. Once you have created the spreadsheet, check the confi dence limits in your 

spreadsheet. They should match those shown Figure 12.20. If they do not, then review 

your spreadsheet for errors. To obtain a number for “T” (cell C28) the Excel ToolPak must be 

installed. To do this, go to the toolbar and select Tools, Add-Ins, and check the box next to 

Analysis ToolPak.

The essential data needed to complete the spreadsheet is:

Parameters (Cell C2) – The parameter to be evaluated should be stated at the top of the 

quadrat columns. In this example, total cover for “seeded” native species was obtained from 

Figure 12.7, but any number of site attributes can be analyzed. Copying column C and pasting it 

in the columns to the right allows for multiple attributes to be analyzed in one spreadsheet.
Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring 

Protocols

Summary

Figure 12.20 – This fi gure shows how confi dence intervals are obtained from a spreadsheet 

developed for rectilinear sampling designs.

B34

A C B

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

28

29

30

31

Quadrat Parameter:

fx

1

Field Data 27

 = AVERAGE (C3:C22)

 = VAR(C3:C22)

 = SQRT(C25/COUNT(C3:C22)) 

 = COUNT(C3:C22)-1 

 = TINV(0.1,C27)

 = C24-C28*C26

 = C24+C26*N28

Mean

Variance

Standard Error

Degrees of Freedom

T

90% Lower Confidence Limit:

90% Upper Confidence Limit:

F16

A C B

2

3

4

5

6

7

8

9

10

11

12

13

14

15

17

18

19

20

21

22

23

24

25

26

28

29

30

31

Quadrat

Parameter:

Native Species Cover

fx

1

27

= 64.2

= 442.4

= 4.7 

= 19

= 1.7

= 56.1 

= 64.2

Mean

Variance

Standard Error

Degrees of Freedom

T

90% Lower Confidence Limit:

90% Upper Confidence Limit:

16

T1

T2

T3

T4

T5

T6

T7

T8

T9

T10

T11

T12

T13

T14

T15

T16

T17

T18

T19

T20

80

90

75

60

45

32

67

50

80

50

30

50

70

90

100

80

70

65

75

25

388

Field Data (Columns C Through H) – The data collected at each quadrat for the parameter of 

interest is typed into these cells. This information comes from the spreadsheets developed for 

each protocol (Soil Cover Protocol – Figure 12.4, Species Cover Protocol – Figure 12.7, Species 

Presence Protocol – Figure 12.8, Plant Density Protocol – Figure 12.9, and Plant Attributes 

Protocol – Figure 12.10).

12.9.1.3 Calculating Confi dence Intervals for Dispersed Sampling Design

There are two methods for determining confi dence intervals for dispersed sampling design – 

the systematic sampling design (See Section 12.7.3.1) and the grid sampling design (See 

Section 12.7.3.2). Confi dence intervals for the grid sampling design are obtained by using the 

spreadsheet shown in Figure 12.20. For the systematic sampling design, Figure 12.21 is used. 

The essential data needed to complete the spreadsheet is:

Dispersed Area ID – For some projects, not all dispersed areas will be sampled. Identify in 

Column A which areas were sampled.

Number of Quadrats (Column B) – Specify the number of quadrats that were sampled for each 

dispersed area.

Parameters (Cell C2) – There may be several parameters collected at each quadrat. The 

parameter to be evaluated should be stated at the top of the quadrat columns. Only one 

attribute can be analyzed on a spreadsheet. Gravel, rock, live and dead vegetation, for instance, 

are often collected in the soil cover protocol. If a statistical analysis of these attributes is 

needed, a spreadsheet must be developed for each attribute. While not all attributes need to 

be statistically analyzed, it is important to analyze those attributes that have been identifi ed for 

measurements of success (e.g., % bare soil or % soil cover).

Field Data (Columns C Through H) – The data collected at quadrats for each dispersed 

area for the parameter of interest is typed into these cells. This information comes from the 

spreadsheets developed for each protocol (Soil Cover Protocol – Figure 12.4, Species Cover 

Protocol – Figure 12.7, Species Presence Protocol – Figure 12.8, Plant Density Protocol – 

Figure 12.9, and Plant Attributes Protocol – Figure 12.10) and it is entered and summarized by

dispersed area.
Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring 

Protocols

Summary

Figure 12.21 – Confi dence intervals for dispersed areas using the systematic sampling design 

can be obtained by using the equations shown in this spreadsheet.

N36

A C B I DEFG H J K

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

28

29

30

31

32

33

34

35

37

38

D2

D1 = AVERAGE(C4:H4)

= AVERAGE(C5:H5)

= AVERAGE(C6:H6)

= AVERAGE(C7:H7)

= AVERAGE(C8:H8)

= AVERAGE(C9:H9)

= AVERAGE(C10:H10)

= AVERAGE(C11:H11)

= AVERAGE(C12:H12)

= AVERAGE(C13:H13)

= AVERAGE(C14:H14)

= AVERAGE(C15:H15)

= AVERAGE(C16:H16)

= AVERAGE(C17:H17)

= AVERAGE(C18:H18)

= AVERAGE(C19:H19)

= AVERAGE(C20:H20)

= AVERAGE(C21:H21)

= AVERAGE(C22:H22)

= AVERAGE(C23:H23)

= B4*14

= B5*15

= B6*16

= B7*17

= B8*18

= B9*19

= B10*110

= B11*111

= B12*112

= B13*113

= B14*114

= B15*115

= B16*116

= B17*117

= B18*118

= B19*119

= B20*120

= B21*121

= B22*122

= B23*123

= B4^2

= B5^2

= B6^2

= B7^2

= B8^2

= B9^2

= B10^2

= B11^2

= B12^2

= B13^2

= B14^2

= B15^2

= B16^2

= B17^2

= B18^2

= B19^2

= B20^2

= B21^2

= B22^2

= B23^2

Q1 Q2 Q3 Q4 Q5 Q6 Average

Transect

ID

Transect

Length

Parameter: Calculations

D3

D13

D10

D11

D12

D15

D16

D20

D19

D18

D17

D14

D8

D9

D7

D6

D5

D4

fx

1

L1 x x1 L1

2

Field Data

= Sum (J4:J23) = Sum (K4:K23)

Equations

= SUM(B4:B23)

= J24/E27

= VAR(I4:I23)

= K24/E27/E27*VAR(I4:I23)

= SQRT(E30)

= COUNT(C4:C23)-1 

= TINV(0.1,E32)

 

= E28-E33*E31 

= E28+E33*E31

27

36

xw

s2(xi )

s2(xw )

SE(xw )

Degrees of Freedom (n-1)

Tn-1, 0.95

 

90% Lower Confidence Limit

90% Upper Confidence Limit

389

Columns I and J – If fewer than 20 dispersed areas were taken, the equations in the cells 

of column I and J that do not have data must be cleared for the spreadsheet to work (see 

highlighted cells in Figure 12.19).

12.9.1.4 Interpreting Confi dence Intervals for Compliance

Confi dence intervals, as stated previously, are used to evaluate the success of a revegetation 

project relative to specifi ed standards or stated goals. Suppose that one of the objectives of 

the revegetation plan was to establish at least 65% total cover over the soil to protect against 

surface erosion. Or stated another way, the objective is no more than 35% bare soil exposed 

one year after revegetation treatments were applied. In the example shown in Figure 12.19 (cells 

E34 and E35), the confi dence interval was below 35%. We can say with 90% level of confi dence 

that the objectives were met. But what if the confi dence interval was either above the standard 

or straddled the standard?

Figure 12.22 shows four possible scenarios for confi dence intervals that the revegetation 

specialist may encounter. Scenario A is a case where the data supports the conclusion at 90% 

confi dence that the project met the standard. Scenario B did not meet the standard because 

the lower confi dence limit was above 35% bare soil.

Scenario C is a case where the mean meets the standard, but the upper confi dence limit is 

above the standard. It cannot be said with 90% confi dence that the standards were met. At this 

point you might ask how important it is to know whether the standards were met or not. If the 

site directly infl uences a live stream, it might be very important to know. However, if streams 

are miles away, it might suffi ce to report that the there was some uncertainty whether the 
Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring 

Protocols

Summary

Figure 12.22 – Four possible scenarios that can be encountered when comparing standards to 

confi dence intervals. Confi dence interval A is clearly acceptable, whereas confi dence interval 

B is clearly unacceptable. Uncertainty arises when the lower confi dence limit is acceptable but 

the upper confi dence limit is unacceptable. This is shown in cases where the mean is in the 

acceptable range (C) and in the unacceptable range (D).

Unacceptable

Acceptable

C

D

B

0%

10%

40%

50%

30%

20%

0%

10%

40%

50%

30%

20%

0%

10%

40%

50%

30%

20%

0%

10%

40%

50%

30%

20%

A

Upper Confidence Limit

Lower Confidence Limit

UCL

LCL

UCL

LCL

UCL

LCL

UCL

LCL

UCL

LCL

390

standards were met. If you determine that you need to be more certain about the results, more 

data will need to be collected.

Scenario D is a case where the mean does not meet the standard, but the lower confi dence 

limit is below the standard of 35% bare soil. One might state that this project did not meet the 

standards, but this still could not be stated with 90% confi dence. In this scenario, more transects 

could be taken to narrow the confi dence interval and hope that the results do not straddle the 

standard. Another option might be to take measures that would decrease the amount of bare 

soil to meet the standards. This could include more seeding or mulch application. A resampling 

of the site later would reveal whether the standards were met.

12.9.2 Determine Treatment Diff erences

There will be opportunities to compare the eff ects of diff erent revegetation products or methods 

on plant establishment and growth using monitoring data. Some of these opportunities will be 

planned (e.g., trying a new product), and some will be mistakes (e.g., inadvertently doubling 

the rate of mulch). Planned or unplanned, when diff erent revegetation activities have occurred 

within a revegetation unit, monitoring can be designed to assess whether there is a diff erent 

vegetative response between those activities or treatments. Note: The monitoring design 

outlined in this section will not replace a well-designed study or experiment; we suggest that if 

more conclusive results of treatment diff erences are required, a study should be designed with 

statistical oversight.

The confi dence interval concept is applied in this section to determine diff erences between 

new revegetation treatments (new treatments) and routine revegetation methods (standard 

treatments). Three possible outcomes are possible when new treatments are compared 

to standard methods: 1) the new treatment results in a favorable increase in the measured 

parameters over the standard treatment (positive diff erence), 2) the new treatment results in a 

decrease (negative diff erence), or 3) there is no positive or negative diff erence (no diff erence). 

Using confi dence intervals, it is possible to determine which of these outcomes is statistically 

supported for any monitoring data set. In this method, the means and variance of means are 

calculated for both the new treatment and standard treatment and a confi dence interval is 

calculated for the certainty of the treatment diff erences.
Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring 

Protocols

Summary

Figure 12.23 – Treatment diff erences can be determined using the following spreadsheet. 

Copy each equation exactly as presented. Fill in cell B2 with the parameters being compared. 

In this example, vegetative ground cover (cell B2) and native species cover (cell C2) are being 

compared. From the two data sets that were summarized from spreadsheets in Figure 12.18, 

12.20, or 12.21, the number of transects, means, and variance of the mean from each can be 

obtained. From this information the spreadsheet calculates the lower and upper confi dence 

limits for each attribute at 90% confi dence.

Treatment: 2X Additional Fertilizer

Veg Ground

Cover Native Species Cover

Parameter

Treatment: Standard Fertilizer Rates

4 Number of Transects:

3

2

1

5

6

7

8

9

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

Mean:

Variance of the Mean:

A

B27

C

12.000000

3.907370

0.002082

29.5000

57.0000

7.5498

12

1.7823

16.0440

42.9560

17.000000

-5.669467

0.000028

-45.0000

63.0000

7.9373

17

1.7396

-58.8077

-31.1923

Number of Transects:

Mean:

Variance of the Mean:

Two Sample T-Test

Degrees of Freedom (df):

T Statistic:

Statistical Significance:

Confidence Interval for Difference in Means

Difference:

Variance of Difference:

Standard Error of Difference:

Degrees of Freedom (df):

T Statistic (90% Critical Value):

Lower 90% Confidence Limit:

Upper 90% Confidence Limit:

10

Parameter

From Spreadsheets 12.18, 12.20, or 12.21

From Spreadsheets 12.18, 12.20, or 12.21

From Spreadsheets 12.18, 12.20, or 12.21

B

From Spreadsheets 12.18, 12.20, or 12.21

From Spreadsheets 12.18, 12.20, or 12.21

From Spreadsheets 12.18, 12.20, or 12.21

=ROUND((B6/B4+B11/B9)^2/(B6^2/B4^3+B11^2/B9^3)-2,0)

=(B5-B10)/SQRT(B6+B11)

=TDIST(B15,B14,2)

=B5-B10

=B6+B11

=SQRT (B20)

=ROUND((B6/B4+B11/B9)^2/(B6^2/B4^3+B11^2/B9^3)-2,0)

=TINV(0.1,B22)

=B19-B23*B21

=B19+B23*B21

fx

B

10

62

47

10

45

23

10

33

10

10

90

40

391

The following example demonstrates how a confi dence interval is determined and how it can 

be used to interpret two data sets. During a hydroseeding operation, someone discovers that 

the rate of fertilizer application was mistakenly applied at twice the normal rate in one area. 

This area was staked in the fi eld and visited by the project team a year later. Some on the team 

believed that there was more vegetative ground cover where fertilizer was doubled; others felt 

that there was actually less. One or two on the team did not believe they could make either 

call. Since monitoring was going to take place a few weeks later, they decided to design a 

monitoring protocol to answer the question, “Was there a positive, negative, or no response of 

vegetative ground cover to the application of additional fertilizer?”

Within the framework of monitoring that was already scheduled for this revegetation unit, a 

monitoring strategy was developed. The soil cover protocol was used (See Section 12.2) along 

with the linear sampling design since this was a road cut (See Section 12.7.1). Each treatment 

area was considered a separate sampling unit, and monitoring took place independently 

of each other. The data from each treatment area was summarized from Figure 12.4 into % 

vegetative ground cover and entered into Figure 12.18 to obtain means and variance of means. 

Number of transects, means, and variance of means for each treatment were then entered 

into Figure 12.23 (cells B4–B6 for the new treatment and B9-B11 for the standard treatment), 

producing a confi dence interval (cells B24 and B25) for comparison.

The results of this analysis showed that the standard rates of fertilizer had an average vegetative 

ground cover of 33% (cell B10) as compared to 62% (B5) for double the fertilizer rate. While this 

looks like an obvious diff erence, how certain could the team be? A confi dence interval was 

derived to answer that question. In this example, the confi dence interval (at 90% confi dence) 

showed that additional fertilizer signifi cantly increased vegetative ground cover. This can 

be shown graphically in Figure 12.24. The 2X fertilizer treatment increased ground cover a 

minimum of 16% over the standard treatment (lower confi dence limit) to as high as 42% ground 

cover (upper confi dence limit).

The team accepted these results and commented that they should increase fertilizer rates for 

future projects. One member posed the question, “We might have achieved better cover on 
Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring 

Protocols

Summary

Figure 12.24 – In the example presented 

in the text and Figure 12.23, confi dence 

intervals are used to answer: 1) how 

vegetative ground cover responds to 

2X the fertilizer rate, and 2) how native 

species cover responds to 2X fertilizer 

rates. The confi dence interval collected 

for the fi rst question was found to be 

positive, indicating that vegetative 

ground cover responds positively to twice 

the fertilizer. The confi dence interval 

for the data set collected for the second 

question was negative, indicating 

that native species cover responded 

negatively to more fertilizer.

80%

60%

40%

20%

0%

-20%

-40%

-60%

-80%

Negative Difference

(decrease in cover)

Positive Difference

(increase in cover)

Vegetative

Ground

Cover

Native

Species

Cover

LCL = 16%

UCL = 42%

LCL = -59%

UCL = -31%

Upper Confidence Limit

Lower Confidence Limit

UCL

LCL

392

this site during the fi rst year, but is it the vegetative cover we really want?” Since the monitoring 

team was still on the project site, they resampled the two areas using the species cover protocol 

(See Section 12.3). In this protocol, native and non-native annuals and perennials were recorded 

at each quadrat. Confi dence intervals were determined for each treatment for native perennial 

cover (Figure 12.23, cells C24 and C25). They learned, in this case, that additional fertilizer had 

a negative eff ect on the establishment of native perennial cover (Figure 12.24). But what if the 

upper confi dence interval in this example had been positive and the lower confi dence interval 

had been negative? In this case, it would have to be concluded that there was no diff erence 

between treatments at 90% confi dence.

12.9.3 Determine Trends

The last of the three objectives for roadside monitoring is assessing trend, or the degree of 

vegetative or soil cover over time. The reason to perform this type of monitoring is usually based 

on the need to understand how growth patterns of certain species or soil cover changes over 

the years. Many monitoring protocols employ permanent monitoring plots or transects that 

can be repeatedly and accurately revisited for sampling. We take the approach that collecting 

data in the same location over time is not feasible for roadside monitoring because of the 

hazards to road maintenance personnel and to the public of placing permanent stakes in road 

corridors. In addition, permanent markers are often hard to relocate years later or can move 

due to the instability of steep cut and fi ll slopes. In this section we off er a statistical analysis that 

does not require locating and resurveying of exact quadrats.

The confi dence interval concept is applied in this section to determine if there are diff erences 

in attributes from one sampling date to another. Three outcomes are possible when comparing 

data from one sampling date to the next: 1) plant or soil cover attributes have increased since 

the last sampling period (positive diff erence); 2) ) plant or soil cover attributes have decreased 

since the last sampling period (negative diff erence); or 3) either there was no change in plant or 

soil cover attributes or the number of samples was inadequate to detect the amount of change 

that occurred. Using confi dence intervals it is possible to make statistically valid statements 

regarding the observed outcomes.
Roadside

Revegetation

Introduction

Initiation

Planning

Implementation

Monitoring 

Protocols

Summary

Figure 12.25 – Changes in attributes over time can be determined using the following 

spreadsheet. The equations shown in the right column (B14 through B25) correspond to the cells 

located in column B (left side spreadsheet). Copy each equation exactly as they appear. Fill in 

cell B2 with the attribute of interest. In this example, the attribute of interest is the crown cover 

of California brome and Idaho fescue (cell C4). From the data sets (see Figures 12.18, 12.20, and 

12.21) obtained on the two sampling dates (2001 and 2006), the number of transects, means, 

and variance of the mean are obtained and copied into rows 4, 5 and 6 for the latest sampling 

date and in rows 9, 10, and 11 for the earlier date. From this information the spreadsheet 

calculates the lower and upper confi dence limit at 90% confi dence.

Sampling Year: 2006

BRCA5

Parameter: % Crown Cover

FEID

Sampling Year: 2001

4 Number of Transects:

3

2

1

5

6

7

8

9

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

Mean:

Variance of the Mean:

20

A

G10

B C

27

19

20

35

22

20

33

15

20

5

10

38.000000

-1.249390

0.219164

-8.0000

41.0000

6.4031

38

1.6860

-18.7954

2.7954

36.000000

5.600000

0.000002

28.0000

25.0000

5.0000

36

1.6883

19.5585

36.4415

Number of Transects:

Mean:

Variance of the Mean:

Two Sample T-Test

Degrees of Freedom (df):

T Statistic:

Statistical Significance:

Difference in Means

Difference:

Variance of Difference:

Standard Error of Difference:

Degrees of Freedom (df):

T Statistic (90% Critical Value):

Lower 90% Confidence Limit:

Upper 90% Confidence Limit:

10

Parameter

From Spreadsheets 12.18, 12.20, or 12.21

From Spreadsheets 12.18, 12.20, or 12.21

From Spreadsheets 12.18, 12.20, or 12.21

B

From Spreadsheets 12.18, 12.20, or 12.21

From Spreadsheets 12.18, 12.20, or 12.21

From Spreadsheets 12.18, 12.20, or 12.21

=ROUND((B6/B4+B11/B9)^2/(B6^2/B4^3+B11^2/B9^3)-2,0)

=(B5-B10)/SQRT(B6+B11)

=TDIST(B15,B14,2)

=B5-B10

=B6+B11

=SQRT (B20)

=ROUND((B6/B4+B11/B9)^2/(B6^2/B4^3+B11^2/B9^3)-2,0)

=TINV(0.1,B22)

=B19-B23*B21

=B19+B23*B21

fx

393

The following example demonstrates how a confi dence interval is determined and how it is 

used to interpret data taken at diff erent sampling dates. Members of the revegetation team 

believed that California brome (Bromus carinatus) was a short lived species; that it established 

well after seeding but by the fi fth year it had very little presence on most sites. They also 

believed that Idaho fescue started out slowly but gained dominance over time. The team felt 

that by understanding these trends they might develop a better seed mix for sites similar to 

the ones they were monitoring. The question they posed was: “is there a positive, negative, or 

no diff erence in the cover of California brome and Idaho fescue from the fi rst year to the fi fth 

year after seeding?”

This question required the use of the species cover protocol (See Section 12.3) since dominance 

was being expressed as % crown cover for each species. Linear Sampling Design was used for 

both monitoring dates because the sampling area was a long cut slope. The data from each 

sampling date was summarized into % cover for California brome (BRCA5) and entered into 

Figure 12.18 to obtain means and variance of means. Number of transects, means, and variance 

of means for each treatment were then entered into Figure 12.25 (cells B9–B11 for earliest 

sampling date and B4 through B6 for latest sampling date), producing a confi dence interval 

(cells B24 and B25) for comparison. Data entry was also done in the same manner for Idaho 

fescue (FEID).

The results of this analysis showed that California brome had an average crown cover of 

35% (B10) in 2001 but decreased to 27% (B5) in 2006, fi ve years later. Was this a statistically 

signifi cantly diff erence? Using confi dence intervals, they found that the means were not 

statistically diff erent at 90% confi dence. This can be shown graphically in Figure 12.26. The 

BRCA5 in 2006 had a maximum of 3% crown cover increase over 2001 and a minimum of -19% 

ground cover over 2001. Because the upper confi dence limit (UCL) was positive and the lower 
Roadside

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Figure 12.26 – In the example presented 

in the text and Figure 12.25, confi dence 

intervals are used to answer whether 

California brome and Idaho fescue 

increased, decreased, or stayed the 

same from 2001 to 2006. The % cover 

of California brome was found not 

to have changed in this time period 

because the lower confi dence limit was 

negative and the upper confi dence limit 

was positive. The confi dence interval 

for the Idaho fescue showed a positive 

diff erence between 2001 and 2006 

(cells C24 and C25). Since the upper and 

lower confi dence limits were positive, 

the diff erences in the means between 

sampling dates was signifi cant at 

90% confi dence.

40%

30%

20%

10%

0%

-10%

-20%

-30%

-40%

Negative Difference

(decrease in cover)

Positive Difference

(increase in cover)

BRCA5

FEID

LCL = 19%

UCL = 36%

LCL = -19%

UCL = 3%

Upper Confidence Limit

Lower Confidence Limit

UCL

LCL

394

confi dence limit (LCL) was negative, the observed data was not adequate to demonstrate a 

change in % crown cover of California brome with 90% level of confi dence.

Idaho fescue, on the other hand, did show an increase in mean cover from 2001 to 2006, from 

5% (cell B10)to 33% (cell B5) respectively. The team could be 90% confi dent that the true percent 

crown cover did indeed increase from 5% in 2001 to 33% in 2006 because the upper confi dence 

limit (UCL) and the lower confi dence limit (LCL) were positive (Figure 12.26).

12.10 SUMMARY

This chapter guided the revegetation specialist through a series of steps for collecting fi eld 

data, developing a sampling design, and statistically analyzing data needed to monitor 

vegetation on roadsides. Monitoring completes the project cycle by answering the question: 

Did we accomplish what we proposed in the revegetation plan?
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13 SUMMARY

Within the transportation community, the challenge is to move beyond regulation-driven 

mitigation approaches and into proactive environmental stewardship. Native plants are 

a foundation of ecological health and function. Roadside revegetation with native plants 

has become a key practice for managing environmental impacts and improving conditions 

for healthy ecosystems. This report synthesizes an integrated approach that can be used to 

eff ectively revegetate roadsides and other disturbance areas associated with road construction, 

modifi cation, or obliteration. The report will be of interest to public and private sector 

practitioners, as well as to transportation and planning professionals, land managers, policy 

makers, and owners and operators of roads. The report can be consulted during any phase of a 

revegetation project. It is also intended to serve as a foundation for future trainings.

After introducing the challenges of roadside revegetation, the report provides a systematic, 

interdisciplinary guide through the process in four stages. The Initiation section helps the user 

bridge terminology and technical expertise between non-engineers and engineers, create key 

relationships, and navigate the decision process in order to initiate a project. Essential steps to 

coordinate revegetation eff orts with road planning and construction are detailed, including 

budgetary and scheduling issues.

Next, the Planning section guides the reader through the process of defi ning project 

objectives, assessing the site, overcoming limitations, strategizing revegetation procedures, 

and integrating the revegetation activities with the road project.

The Implementation section provides information on how to make the project unfold in the 

fi eld, from coordinating contracts and creating budgets and timelines to caring for the plants 

as they mature. Implementation Guides are fi lled with practical how-to information for many 

cost-eff ective site treatments and revegetation tactics that are used to revegetate roadsides.

Finally, the Monitoring and Management section describes how to assess the eff ectiveness 

of the revegetation project to correct any shortcomings, improve practice, and add to 

future knowledge. Example monitoring protocols are included to guide readers in selecting 

appropriate monitoring methods for the project’s goals.

When planned well, the successful establishment of desirable vegetation supports 

transportation goals for safety and effi ciency, stabilizing slopes, reinforcing infrastructure, 

and improving the road user’s experience by creating natural beauty and diversity along the 

roadside. Healthy native plant communities are often the best long-term defense against 

invasive and noxious weeds. Maintenance costs for managing problematic vegetation are 

reduced, as is the controversy that sometimes results when weeds from roadsides invade 

neighboring lands, or where pollution from herbicide use is a concern.

Revegetation success is a key factor in determining whether the over 12 million acres that 

make up the transportation corridor of the United States will be hospitable environments 

to plants and other forms of life – or a wasteland. It is hoped that continuing improvements 

in interagency cooperation, enlightened policies, better science and technology, and the 

dedication and innovation of fi eld-based practitioners will continue to build a foundation for a 

more sustainable future.
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396

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