Soil-Disturbance 

Field Guide

U.S. Department of 

Agriculture

Forest Service

National Technology & 

Development Program

0819 1815—SDTDC

1940 Inventory & Monitoring

August 2009

Carolyn Napper, Soil Scientist

USDA Forest Service

San Dimas Technology and Development Center

Steven Howes, Soils Program Leader (Retired)

USDA Forest Service

Pacific Northwest Region

Portland, Oregon

Deborah Page-Dumroese, Ph.D., Research Soil Scientist

USDA Forest Service

Rocky Mountain Research Station

Moscow, Idaho

August 2009

The information contained in this publication has been developed for the guidance of employees of 

the Forest Service, U.S. Department of Agriculture, its contractors, and cooperating Federal and 

State agencies. The Forest Service assumes no responsibility for the interpretation or use of this 

information by other than its own employees. The use of trade, firm, or corporation names is for 

the information and convenience of the reader. Such use does not constitute an official evaluation, 

conclusion, recommendation, endorsement, or approval of any product or service to the exclusion 

of others that may be suitable.

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Soil-Disturbance 

Field Guide

Table of Contents

Chapter 1—Introduction ......................................................................................................................................... 1

Background .............................................................................................................................................................. 1

Field Guide Organization ......................................................................................................................................... 2

Planning and Implementing Projects Using Visual Soil-Distrubance Classes ........................................................ 3

 Onsite Investigations .......................................................................................................................................... 3

 Soil Risk Ratings ................................................................................................................................................ 3

 Desired Soil Conditions ...................................................................................................................................... 4

 Soil-Quality Monitoring ....................................................................................................................................... 5

Summary ................................................................................................................................................................. 6

Chapter 2—Using the Soil-Disturbance Field Guide .............................................................................................. 7

Soil-Disturbance-Class Attributes ........................................................................................................................... 7

 Forest-Floor Attributes ........................................................................................................................................ 8

 Surface Soil-Attributes ..................................................................................................................................... 10

 Subsurface Attributes ....................................................................................................................................... 16

Soil-Disturbance Classes ...................................................................................................................................... 20

Chapter 3—Defining Soil-Disturbance Class 0-Undisturbed Soil Surface .......................................................... 23

Chapter 4—Defining Soil-Disturbance Class 1 Disturbance ................................................................................ 31

Chapter 5—Defining Soil-Disturbance Class 2 Disturbance ................................................................................ 53

Chapter 6—Defining Soil-Disturbance Class 3 Disturbance ................................................................................ 67

Chapter 7—Mechanical Equipment Used in Harvest and Post-Harvest

Operations and Their Potential Soil Impacts ......................................................................................................... 81

 Harvest Equipment ........................................................................................................................................... 81

 Post-Harvest Mechanical Treatment Equipment .............................................................................................. 94

 Soil Restoration Equipment .............................................................................................................................. 97

References ........................................................................................................................................................... 99

Appendix ............................................................................................................................................................ 101

1

Chapter 1

CHAPTER 1 

Introduction

Background

The San Dimas Technology and Development Center of the 

Forest Service, U. S. Department of Agriculture, developed the 

soil-disturbance field guide as a soil monitoring tool to identify soildisturbance classes. The field guide provides detailed descriptions 

and photographic examples—over a wide range of climatic and 

vegetative conditions—of the undisturbed soil condition and the three 

soil-disturbance classes. The field guide is not only a training tool 

but also a tool for individuals, such as soil scientists, silviculturists, 

contract inspectors, fuel management specialists, and other 

resource managers to use when conducting field soil-disturbance 

assessments. 

The field guide also is a tool to improve communication between 

land managers and contractors, equipment operators, and public 

interest groups. Much has been written (i.e., opinions and scientific 

data) about the potential effects of soil disturbance on vegetative 

growth and other ecosystem functions. In order to have a clear 

understanding of these interactions, it requires that everyone speak 

the same language to help develop a soil-management prescription.

The Forest Service considers the sustainable production of 

natural resources and the maintenance of soil and water quality 

high priorities as it plans and implements management activities. 

Legislation, such as the Organic Administration Act of 1897, 

the Multiple Use and Sustained Yield Act of 1960, the National 

Environmental Policy Act of 1969, and the National Forest 

Management Act of 1976, speak either directly or indirectly about 

providing high-quality water, providing sustainable production of 

timber and forage, improving growth of forests and grasslands, 

disclosing impacts of proposed activities on soils, and not degrading 

the productive potential of the national forests. Little definitive 

direction was given on how to accomplish these goals.

In response to these laws, all Forest Service regions developed soil 

quality standards and implemented direction or guidance relating 

to maintenance and protection of soil productivity. Over the years, 

a wide array of monitoring protocols and definitions of detrimental 

soil conditions have been developed to determine if, in fact, agency 

management practices met this direction. These uncoordinated 

efforts, while well intentioned, created a number of problems. The 

most significant problem has been the inability to compare and/or 

share monitoring data across administrative boundaries because 

of (1) inconsistent or poorly designed sampling protocols, and (2) 

inconsistent descriptions of soil-disturbance categories and differing 

definitions of detrimental soil conditions. 
2

Soil-Disturbance Field Guide

The development of reliable monitoring protocols for assessing 

and comparing soil disturbance resulting from logging operations 

is a key component of an adaptive management process for forest 

soil conservation (Curran et al. 2005). Uniform and unambiguous 

definitions of soil-disturbance categories must be part of such 

protocols if accurate, consistent, and statistically sound assessments 

are to be made. Such categories must also relate to forest 

productivity and hydrologic function (Curran et al. 2007).

A proposed soil-quality protocol that incorporates both a statistically 

rigorous sampling protocol and definitions of visually observable soildisturbance categories has been developed by the Forest Service 

and is available in the Forest Soil Disturbance Monitoring Protocol 

(Page-Dubroese et al. 2009a and b). 

This field guide is a companion document to the national protocol 

(Page-Dumroese et al. 2009a and b), which also can be used on its 

own to identify disturbance classes and to monitor soil conditions 

before and after treatment.

Questions may arise regarding the accuracy and consistency of 

visual soil-disturbance assessments. Other forest management 

entities (Scott 2007, Curran et al. 2000) have found that such soildisturbance observations work effectively if they are supported by 

a disciplined training program, frequent checking by experienced 

individuals, and training of observers. This field guide is intended to 

be used in such training efforts, and to help promote the high level 

of uniformity and consistency required when conducting visual soildisturbance assessments. More importantly, it will improve the level 

of communication among all parties with an interest in forest soildisturbance monitoring. 

Chapter 1 describes the role of a visual guide within the context of 

soil risk ratings and soil-quality monitoring, and evaluates the effects 

of soil disturbance. Chapter 2 defines and describes the visual 

attributes that determine a soil-disturbance class. Chapters 3 through 

6 describe each disturbance class, its criteria, and where it may 

occur. Representational photographs also are included. By comparing 

photographs field personnel can determine which soil-disturbance 

class the management-induced disturbance falls within. Chapter 7 

provides examples of mechanized equipment commonly used to 

implement harvest prescriptions. 

Field Guide Organization
3

Chapter 1

One should follow a logical process when planning any grounddisturbing activity to ensure that soils and project-design features 

are considered when developing the desired conditions. Onsite 

investigations within a project area will determine the soils present 

and how the soils may have been impacted by past management 

activities. Soil-disturbance classes help to quantify the degree, 

extent, and distribution of existing impacts. Data collected as part of 

onsite investigations should be supplemented with other information, 

such as soil surveys, aerial photography, and management direction. 

Rating, or predicting the degree of risk of detrimental soil disturbance 

resulting from equipment operations, is a component of an adaptive 

management process for forest soils (Curran et al. 2005). Ideally, 

detrimental soil conditions are defined based on research designed 

to measure the effect of disturbance on specific soil types to 

subsequent tree growth. In the absence of such data, determinations 

are made about these cause-and-effect relationships. 

Soil risk ratings are one way to look at specific soil types and their 

individual properties, and make determinations about how changes 

in these properties, brought about by equipment operations or fire, 

may affect site productivity and hydrologic function. This process 

is described in detail in Reynolds et al. (2008). A risk-rating model 

has been developed that, in brief, views each soil in terms of a bank 

account. Some assumptions include:

• Degree and extent of soil disturbance has a potentially greater 

effect on shallow or infertile soil than it does on deep or fertile 

soils.

• Soils supporting vigorous plant growth are less likely to be 

affected by soil disturbance than are less favorable soils.

• Soil impacts are more likely to reduce vegetative growth under 

stressful climatic conditions.

Soil-quality objectives for specific land-management projects can 

be established based on soil types and their corresponding risk 

ratings. For example, soils with low risk of damage by equipment 

operations may be able to sustain more class-3 soil disturbances 

than soils with a high degree of risk. Another consideration is that 

Soil Risk Ratings

Planning and 

Implementing Projects 

Using Visual

Soil-Disturbance 

Classes

Onsite Investigations
4

Soil-Disturbance Field Guide

soils with a low degree of risk of damage from equipment operations 

may be able to withstand more equipment passes without incurring a 

class-3 soil disturbance. Many factors affect the risk rating, including 

soil texture, slope, and ecological setting. In the past, a single soilquality objective was applied to all soils regardless of differences in 

properties or degree of risk. Using risk ratings and past monitoring 

information, if available, should allow for more flexibility in developing 

soil-quality objectives during the project-planning process.

Soil risk ratings can be generated by running the model on the 

National Soils Information System (NASIS) database (where soil 

surveys are available), or by using a field key and making onsite 

observations of soil properties. 

Soil risk ratings are currently based on assumptions rather than on 

quantitative research. Therefore, they need to be verified or adjusted 

as part of the adaptive-management process. Soil-disturbance 

assessments, using visually observable disturbance classes, can 

provide some of the information needed to make these adjustments. 

Desired soil conditions for specific land-management activities can 

be based on the analysis of soil types, their characteristics, and their 

corresponding risk ratings. Desired soil conditions can be expressed 

as the allowable extent (usually expressed as a percentage of area 

occupied by each of the three soil-disturbance categories). However, 

there are other factors that contribute to the overall effect(s) of soil 

disturbance in a specific project area. These include:

Degree of disturbance. The amount of change in a particular soil 

property and the depth to which that change occurs (this is reflected 

in the soil-disturbance class).

Duration of disturbance effects. The length of time that the 

disturbance effects can be expected to persist. (This is also reflected 

somewhat in the soil-disturbance class and risk rating).

Distribution of disturbance. The pattern of soil disturbance across 

a project area or landscape. (For example, evenly spaced small 

polygons versus single large polygons or linear polygons). The 

pattern of soil disturbance across a project area is probably the single 

most important factor in determining potential effects.

Location of soil disturbance in relation to other resource values. 

The proximity of soil disturbance to other resource values, such as 

streams, riparian areas, critical habitat, heritage sites, etc., also can 

be an important consideration when determining effects.

Desired Soil Conditions
5

Chapter 1

Soil variability. Soil differences across a project area may 

necessitate a set of desired soil conditions and project-design 

features for a specific project.

These five factors need to be considered when establishing desired 

soil conditions and project-design features for each project. Applying 

a single set of soil-quality standards to all projects is no longer 

scientifically supportable.

Soil-disturbance classes can be used quickly and easily to assess 

effectiveness of management activities in achieving desired soil 

conditions. If desired soil conditions are expressed in terms of soildisturbance classes, then soil-quality monitoring following the national 

protocol can be used to determine if desired conditions have been 

met.

Quantitative physical indices of soil quality, such as strength, 

macropore-space distribution, or bulk density, can be assigned for 

specific soils. These indices can be related to specific soil types 

and disturbance classes. However, if meaningful data are to be 

obtained, many quantitative measurements need to be taken as part 

of controlled studies.

Describing or defining soil disturbance in terms of variables, such as 

soil strength, pore space, or bulk density, makes assessing change 

resulting from management activities difficult and expensive. Soil 

variability, and the variation in the pattern of equipment operations 

or burning, further complicates assessments. Other factors, such 

as climate (macro and micro), vegetation-management practices, 

genetics, and hazardous-fuels distribution also can affect the extent 

and degree of soil disturbance and its subsequent effects. However, 

they are often overlooked.

Sometimes several forms of soil disturbance can occur at one place, 

making assessments difficult. For example, forest-floor removal, 

displacement, and compaction often can occur in the same location. 

Most soils exhibit bulk-density increases with depth. In soils where 

displacement has occurred, natural-density increases can be 

confused with compaction.

One way to simplify soil-disturbance assessments is to use visual 

classes to describe the degree of change from the natural (or 

preproject) conditions resulting from the application of management 

activities. Soil-disturbance classes also allow soil scientists to 

communicate the desired soil conditions and to display the effects to 

Soil-Quality Monitoring
6

Soil-Disturbance Field Guide

contract administrators, other resource specialists, and the public. On 

the landscape, soil disturbance occurs in a continuum—from little or 

none to very severe. Disturbance classes allow an observer to divide 

the continuum into meaningful and describable segments.

Soil-disturbance classes attempt to combine important disturbancetype features into easily observable groups. Soil-disturbance 

categories described in this field guide should be used for descriptive 

use only. For the most part, effects of the various degrees of soil 

disturbance on the productive potential or hydrologic function are not 

yet known or have not been validated. However, assumptions based 

on existing research or personal experience can be made.

When planning and implementing management activities using soildisturbance classes, this process may be helpful: 

1. Collect existing information on the project area.

• Review current and past aerial photography.

• Obtain documentation of previous management activities 

(if available).

• Review existing soil-survey information.

• Determine soil-resource issues.

2. Conduct onsite investigations to determine soil characteristics 

and impacts of past management activities. Disturbance 

classes can be used to quantify management impacts on soils. 

(Follow the Forest Soil Disturbance Monitoring Protocol, volume 

2.)

3. Determine the risk of soil disturbance resulting from planned 

management activities (equipment, fire) using current risk-rating 

models.

4. Establish desired soil conditions and develop project-design 

features needed to achieve them.

5. Conduct post-project monitoring following the national protocol 

to determine if desired soil conditions have been met.

6. Adjust soil risk ratings if needed.

7. Coordinate with the regional soil scientist on the need for more 

quantitative monitoring.

Summary
7

Chapter 2

The field guide is intended for individuals conducting field soildisturbance assessments. However, before starting an assessment 

it may be helpful to review the available information on the project 

area. Background information on the soils within the units will help to 

prioritize sampling areas and to identify potential areas of concern. 

Numerous sources of information are available including:

• Watershed and landscape analysis. 

• Management-activity records. 

• Aerial photographs. 

• Soil resource inventories. 

• Soil risk ratings. 

• Watershed improvement needs inventories.

• Soil-management prescription.

Field monitoring requires identifying specific soil attributes to 

determine the soil-disturbance class. A systematic method for 

observing soil conditions (physical, chemical, and biological) is 

necessary to make an accurate soil-disturbance-class determination. 

The following list of attributes is from the National Soil Disturbance 

Monitoring Protocol, volume 2, included in appendix A. Soil scientists, 

silviculturists, and contract inspectors can determine accurately the 

overall disturbance-class rating by following a systematic review of 

key soil attributes. To ensure an accurate soil-disturbance rating, 

the reviewer should be thoroughly familiar with the undisturbed soilcondition attributes for the forest floor, surface, and subsurface. 

Forest-Floor Attributes:

• Forest-floor impacted.

• Live plant.

• Fine woody. 

• Coarse woody. 

• Bare soil.

• Rock.

Surface-Soil Attributes:

• Topsoil displacement.

• Erosion.

• Ruts – shallow.

• Ruts – moderate.

• Ruts – deep.

• Puddled conditions.

• Burning – low severity.

• Burning – moderate severity.

• Burning – high severity.

CHAPTER 2

Using the Soil-Disturbance 

Field Guide

Soil-Disturbance-Class 

Attributes
8

Soil-Disturbance Field Guide

Subsurface Attributes:

• Compaction – shallow.

• Compaction – moderate.

• Compaction – deep.

• Platy structure. 

• Massive structure.

The forest-floor material (litter, duff, live vegetation) includes all 

organic horizons above the mineral soil surface. Description of the 

forest floor provides valuable information of forest-floor nutrients 

(Page-Dumroese et al. 2000) and soil-cover presence is useful in 

applying erosion-prediction models. Figures 2-1 through 2-6 illustrate 

forest-floor attributes.

Figure 2-1—Live vegetation dominates this project area, and rapidly provides soil 

cover.

Figure 2-2—Fine-woody material is approximately the size of the 100-hour fuels.

Forest-Floor Attributes
9

Chapter 2

Figure 2-3—Coarse-woody material left onsite after completing the harvest.

Figure 2-4—Coarse-woody material remains on the landing, and is dispersed 

throughout the treatment unit.
10

Soil-Disturbance Field Guide

Figure 2-5—Bare soil is identified within the tape-measure boundary.

Figure 2-6—Soil cover is dominated by rock.

Topsoil (surface soil) primarily includes the mineral-soil A horizons, 

but if the A horizon is shallow or undeveloped, it may include other 

horizons. Soil-displacement involves the removal of soil material from 

one place to another. It often is the result of scraping with a blade, 

the turning of tracks or wheels, or the dragging of logs or whole trees. 

Surface soils, high in organic matter, are important to maintaining 

site productivity. They usually have high infiltration rates and absorb 

water readily. Subsoils tend to be more erodible than surface soil. 

Maintenance of surface soils is an important objective, especially in 

Soil Displacement

Surface-Soil Attributes
11

Chapter 2

shallow soils, or where they are particularly thin. Soil displacement 

can occur over a large continuous area and is often more common 

than other types of soil disturbance. Figure 2-7 illustrates surface-soil 

displacement.

Figure 2-7—Displaced soil creates a berm along the skid trail by moving the topsoil 

(A horizon).

Erosion is the detachment and movement of soil or rock by water, 

wind, ice, or gravity (Soil Science Society of America 2001). Erosion 

indicators include the presence of rills or gullies, pedestaling of rocks/

plants, erosion pavement, and light-colored soil horizons exposed at 

the surface. Figures 2-8 through 2-10 illustrate erosion.

Figure 2-8—Rill erosion is prevalent on this cutslope due to lack of soil cover. 

Steep and long slope lengths without vegetation or soil cover are susceptible to 

accelerated erosion. 

Erosion
12

Soil-Disturbance Field Guide

Figure 2-9—An example of pedestaling shows that the unprotected soil is washed 

away.

Figure 2-10—An area with erosion pavement shows that all the fine soil material 

has been removed.

Surface-Soil Attributes (cont)
13

Chapter 2

Ruts vary in depth, but are primarily the deformation of the soil from 

equipment operation during suboptimal moisture conditions or on 

soils with low bearing strength. Compacted ruts can channel water 

downslope causing erosion and slowing regeneration. Figures 2-11 

through 2-14 illustrate rutting.

Figure 2-11—Shallow rutting is evident on the skid trail.

Figure 2-12—Moderate rutting on the skid trail, during suboptimal moisture 

conditions.

Surface-Soil Attributes (cont)

Rutting
14

Soil-Disturbance Field Guide

Figure 2-13—Moderate ruts from a single vehicle pass.

Figure 2-14—Deep ruts formed in soils with a high water table.

This field guide focuses on soil disturbance from mechanized 

equipment. However, once an area has been mechanically treated, a 

secondary follow-up treatment may include burn piles or prescribed 

burning to achieve resource objectives. In recognition that these 

conditions may exist when post-treatment monitoring is conducted, 

the values of low, moderate, and high burn severity are included in 

the guide. Evaluating soil burn severity can determine if increased 

erosion or the amount of remaining forest-floor nutrients is a concern 

from the treatment. Figures 2-15 through 2-17 illustrate the burnseverity classes. 

Surface-Soil Attributes (cont)

Soil Burn Severity
15

Chapter 2

Figure 2-15—Low soil burn severity. Pile burning of forest residues shows no 

evidence of soil heating. Black ash and incomplete combustion of materials on the 

surface indicates low soil burn severity. 

Figure 2-16—Moderate soil burn severity. Dark ash is prevalent but the soil 

structure is intact, and water repellency is discontinuous.

Surface-Soil Attributes (cont)
16

Soil-Disturbance Field Guide

Figure 2-17—High soil burn severity. Ash may be white or reddish. The soil 

structure is loose and powdery (structureless).

Soil compaction is an increase in the soil bulk density, and a 

concomitant decrease in the soil porosity, by the application of 

mechanical forces to the soil (Soil Science Society of America 

2001). There are three levels and depths of compaction: shallow (0 

to 4 inches), moderate (up to 12 inches), and deep (over 12 inches).

Figures 2-18 through 2-20 illustrate soil compaction.

Figure 2-18—Compaction shallow. Increased resistance and compression is 

evident but the rocky soils ameliorate the depth and severity of compaction.

Subsurface Attributes

Soil Compaction
17

Chapter 2

Figure 2-19—Compaction moderate. Increased resistance is evident to 

approximately 8 inches. 

Figure 2-20—Compaction deep. Increased resistance is greater than 12 inches in 

depth on this main skid trail.

Surface-Soil Attributes (cont)
18

Soil-Disturbance Field Guide

A platy soil structure is evident with flat-lying or tabular structure in 

the mineral soil. Massive indicates no structural units are present, 

and soil material is a coherent mass. A puddled soil condition results 

from both shearing and compactive forces, which destroys natural 

structure and results in a condition of greatly reduced pore space 

(Soil Science Society of America 2001). Visual attributes are defined 

as shallow (to 4 inches in depth), moderate (extends 12 inches 

deep), and deep (greater than 12 inches). Figures 2-21 through 2-24 

illustrate platy, massive, and puddled conditions. 

Figure 2-21—A puddled soil condition shows the effect of both a structureless 

condition and an impaired hydrologic function.

Figure 2-22—Shallow platy structure is evident in the top 4 inches, as the area 

recovers from previous harvesting.

Surface-Soil Attributes (cont)

Platy/Massive Soil 

Structure
19

Chapter 2

Figure 2-23—Massive (structureless) is found in this skid trail.

Figure 2-24—Deep platy structure is evident in the main skid trail.

Surface-Soil Attributes (cont)
20

Soil-Disturbance Field Guide

The soil-disturbance continuum extends from undisturbed to 

increased levels of disturbance. Visual attributes help select the soildisturbance class ranging from 0 (undisturbed) to 3 (highly disturbed). 

Once a systematic method is completed for observing soil conditions, 

the correct soil-disturbance category is applied to that point. Figures 

2-25 through 2-28 illustrate the undisturbed soil condition and the 

three soil-disturbance classes.

Figure 2-25—Soil-disturbance class 0, undisturbed.

Figure 2-26—Soil-disturbance class 1, faint wheel tracks, forest-floor intact, no 

signs of displacement or increased compaction.

Undistrubed Soil 

Condition

Soil-disturbance Class 0 

– Undisturbed

• No evidence of past equipment.

• No depressions or wheel tracks.

• Forest-floor layers are present

 and intact.

• No soil displacement evident.

• No management-generated soil

 erosion.

• No management-created soil

 compaction.

• No management-created platy

 soils.

Soil-Disturbance Class 1

• Wheel tracks or depressions

 evident, but faint and shallow.

• Forest-floor layers are present

 and intact.

• Surface soil has not been

 displaced.

• Soil burn severity from

 prescribed fires is low

 (slight charring of vegetation,

 discontinuous).

• Soil compaction is shallow 

 (0 to 4 inches).

• Soil structure is changed from

 undisturbed conditions to

 platy or massive albeit 

 discontinuous.
21

Chapter 2

Figure 2-27—Soil-disturbance class 2, wheel tracks are evident, forest-floor layers 

are missing, soil-displacement is evident, and soil compaction is increased (up to 12 

inches).

Figure 2-28—Soil-disturbance class 3, wheel tracks are evident, forest-floor layers 

are missing, signs of surface-soil removal are evident, and soil compaction is 

increased (over 12 inches in depth).

Temporal and spatial effects of mechanical disturbance need to 

be considered as a component of the monitoring effort. Different 

treatment prescriptions and equipment will yield different effects and 

must be matched to the area soil prescription.

Soil Disturbance Class 3

• Wheel tracks or depressions are 

 evident and deep.

• Forest-floor layers are missing.

• Surface soil is removed through 

 gouging or piling.

• Surface soil is displaced.

• Soil burn severity from 

 prescribed fires is high (white or 

 reddish ash, all litter completely 

 consumed, and soil structureless).

• Soil compaction is persistent

 and deep (greater than 12 

 inches).

• Soil structure is changed from 

 undisturbed and is platy or 

 massive throughout.

Soil Disturbance Class 2

• Wheel tracks or depressions are 

 evident and moderately deep.

• Forest-floor layers are partially 

 missing.

• Surface soil partially intact and 

 maybe mixed with subsoil.

• Soil burn severity from

 prescribed fires is moderate

 (black ash evident and water 

 repellency may be increased 

 compared to preburn condition).

• Soil compaction is moderately 

 deep (up to 12 inches).

• Soil structure is changed from 

 undisturbed conditions and may 

 be platy or massive.

23

Chapter 3

The soil-disturbance class 0 is defined by the following 

characteristics:

• No evidence of past equipment.

• No depressions or wheel tracks.

• Forest-floor layers are present and intact.

• No soil-displacement evident.

• No management-generated soil erosion.

• No management-created soil compaction.

• No management-created platy soils.

Soil-disturbance class 0 may be found throughout the landscape. 

Steep hillslopes, riparian- or streamside-management zones, and 

some research-natural areas may have little to no managementinduced disturbance. Review aerial photographs and available standlevel data if the area was previously treated. Aerial photographs help 

identify untreated areas adjacent to monitoring locations. Undisturbed 

areas are beneficial for monitoring calibration. Stand records have 

considerable data, such as when entries were made, treatment 

prescription, and follow-up treatments implemented. Soil-specialist 

reports identify the soil type within the project area and address risks 

and mitigation requirements. 

Figure 3-1—Soil-disturbance class 0 

– undisturbed.

CHAPTER 3

Defining Soil-Disturbance 

Class 0 – Undisturbed 

Soil Surface

• The forest floor is intact, no 

indications of past equipment 

operation. 

• Surface litter includes fine and 

coarse woody material and 

may have plants. 

• Deep organic material covers 

the A horizon.

• Both large and small roots 

extend throughout the soil 

profile. 

• Surface soil structure is 

generally granular.

• No resistance to penetration 

with a shovel.

Soil-Disturbance Class 0
24

Soil-Disturbance Field Guide

Figures 3-2 through 3-12 illustrate soil-disturbance class 0. The 

Ecomap information throughout this publication is taken from a 1994 

USDA Forest Service document, which is included in the references. 

The figure captions also include the photo location. 

Figure 3-2—Vegetation: Sitka spruce and western hemlock. A thick organic 

layer including feather moss covers the mineral soil surface. The surface soil 

texture is a gravelly silt loam. Ecomap Section M245C - Southern Alexander 

Archipelago, Tongass National Forest, Alaska Region.

Soil-disturbance Class 0 

– Undisturbed

• No evidence of past equipment.

• No depressions or wheel tracks.

• Forest-floor layers are present

 and intact.

• No soil displacement evident.

• No management-generated soil

 erosion.

• No management-created soil

 compaction.

• No management-created platy

 soils.
25

Chapter 3

Figure 3-3—Vegetation: Grand fir and Douglas fir. The soils are influenced by 

volcanic ash from Mount Mazama. The surface soil texture is silt loam. Ecomap 

Section 332G - Blue Mountains, Umatilla National Forest, Pacific Northwest Region.

Figure 3-4—Vegetation: Douglas fir and mixed conifer. The surface soil texture 

is sandy loam. Ecomap Section M261E - Sierra Nevada, Lake Tahoe Basin 

Management Unit, Pacific Southwest Region.
26

Soil-Disturbance Field Guide

Figure 3-5—Vegetation: Grand fir and Douglas fir, western spruce fir, and western 

ponderosa forest. The surface soil texture is loamy sand. Ecomap Province M332A 

- Idaho Batholith, Idaho-Panhandle National Forest, Northern Region. Undisturbed 

areas are often found adjacent to previous timber-harvest units, as in this case. 

Figure 3-6—Vegetation: Longleaf pine and slash pine. The surface soil texture 

is sandy loam. Ecomap Section 232B - Coastal Plains and Flatwoods, Conecuh 

National Forest, Southern Region. 
27

Chapter 3

Figure 3-7—Close-up view of the undisturbed soil structure in the unit. Vegetation: 

Longleaf pine and slash pine. The surface soil texture is sandy loam. Ecomap Section 

232B - Coastal Plains and Flatwoods, Conecuh National Forest, Southern Region.

Figure 3-8—Vegetation: Sitka spruce and western hemlock. The surface soil texture 

is a gravelly silt loam. Ecomap Section M245C - Southern Alexander Archipelago, 

Tongass National Forest, Alaska Region. Undisturbed areas can be found adjacent to 

previously harvested areas. 

Undisturbed area
28

Soil-Disturbance Field Guide

Figure 3-9—Vegetation: Northern hardwoods. The surface soil texture is sandy 

loam. Ecomap Section 212H - Northern Great Lakes, Hiawatha National Forest, 

Eastern Region.

Figure 3-10—Close-up view of the surface soil texture found in figure 3-9.
29

Chapter 3

Figure 3-11—Vegetation: Western spruce and fir forest with spruce dominating 

the overstory, and subalpine fir in the understory. The surface soil texture is sandy 

loam. Ecomap Section M331A - Yellowstone Highlands, Shoshone National Forest, 

Rocky Mountain Region.

Figure 3-12—Close-up of the soil structure from this undisturbed area in figure 3-11. 

Notice the abundance of roots throughout the sample. 

31

Chapter 4

The soil-disturbance class 1 is defined by the following 

characteristics:

Soil surface:

• Faint wheel tracks or slight depressions evident.

• Forest-floor layers present and intact.

• Surface soil has not been displaced and shows minimal mixing 

with subsoil.

• Low soil burn severity. Litter slightly charred or partially 

consumed. Duff largely intact. Water repellency is similar to 

pre-burn conditions.

• Soil compaction is shallow. [Compaction in the surface soil (top 

0 to 4 inches) is slightly greater than observed under natural 

conditions.]

Soil physical conditions:

• Change in soil structure from granular structure to massive or 

platy structure; restricted to the surface soil.

• Platy structure is noncontinuous.

Soil-disturbance class 1 can be found throughout the landscape in 

both recent and older treatment units. Depending on the recovery 

time, look for soil-disturbance class 1 on secondary or tertiary 

skid trails, winter-logged units, single-pass trails, and low-severity, 

broadcast burn areas. 

Areas that were managed 20 to 30 years ago may still show 

indications of soil disturbance. Surface characteristics may be 

masked by pine needles and accumulated litter, but it is not 

uncommon to note slight depressions from equipment or greater 

penetration resistance on major skid trails, access roads, or landings. 

Areas monitored that demonstrate attributes of previous activity 

should be categorized as class-1 disturbance. 

Figure 4-1—An illustration of soildisturbance class 1.

CHAPTER 4

Defining SoilDisturbance Class 1

• Wheel tracks or depressions 

evident but faint and shallow.

• Forest-floor layers are present 

and intact.

• Surface soil has not been 

displaced.

• Soil burn severity from 

prescribed fires is low (slight 

charring of vegetation, 

discontinuous).

• Soil compaction is shallow (0 

to 4 inches).

• Soil structure is changed 

from undisturbed conditions 

to platy or massive albeit 

discontinuous.

Soil-Disturbance Class 1
32

Soil-Disturbance Field Guide

Figures 4-2 through 4-39 provide photographic examples of class-1 

soil disturbance from all regions of the country.

Figure 4-2—The thinning operation in this unit was completed 1 month prior to this 

photograph. The skid trail is evident, but the forest-floor layers are present and 

intact with no signs of soil displacement. 

Figure 4-3—Vegetation: Longleaf pine and slash pine. The surface soil texture 

is sandy loam. The treatment prescription was to reduce fire risk with a biomass 

removal of pine and hardwoods. A tracked feller-buncher and rubber-tired skidders 

yarded whole trees to the landing for processing. The photos were taken within 

1 month of treatment (February 2007). Ecomap Section 232C - Atlantic Coastal 

Flatlands, Francis Marion and Sumter National Forest, Eastern Region.
33

Chapter 4

Figure 4-4—Vegetation: White fir and ponderosa pine. The surface soil texture is 

gravelly sandy loam. These photos were taken during an active thinning (November 

2006) to reduce fuels using cut-to-length logging equipment. A rubber-tired fellerbuncher and a forwarder were followed by an excavator with a mowing head to 

reduce ladder fuels. Ecomap Section M261 E - Sierra Nevada, Lake Tahoe Basin 

Management Unit, Pacific Southwest Region.

Figure 4-5—The soil-disturbance class 1 is identified after removing the cut-tolength logs and chipping the residual vegetation. Slight wheel tracks are evident but 

operations over slash with low-ground-pressure equipment reduce soil impacts. 
34

Soil-Disturbance Field Guide

Figure 4-6—Vegetation communities include Douglas fir, white fir, ponderosa pine, 

and mixed-hardwood forest. The surface soil texture is sandy loam. These photos 

illustrate a thinning to promote tree growth by reducing competition. Treatment was 

implemented within the past 3 months (November 2006). Ecomap Section M261B - 

Northern California Coast Range, Shasta-Trinity National Forest, Pacific Southwest 

Region.

Figure 4-7—Using an available cutslope, the soil scientist identifies the soil type, 

structure, and natural soil resistance prior to monitoring the unit. 
35

Chapter 4

Figure 4-8—Vegetation: Jeffrey pine forest. The surface soil texture is gravelly 

sandy loam. The treatment is a fuels-reduction prescription designed to create 

defensible space adjacent to main transportation corridors. This was an activethinning project using a feller-buncher and grapple-skidder to yard whole trees to 

the landing (photo November 2006). Ecomap Section M261G -Modoc Plateau, 

Lassen National Forest, Pacific Southwest Region.

Figure 4-9—A closeup of the results of a single equipment pass, which leaves the 

litter layer intact.
36

Soil-Disturbance Field Guide

Figure 4-10—Vegetation: Ponderosa pine. The surface soil texture is gravelly 

sandy loam. The treatment is part of a larger project (Metolius Basin Project Area), 

with the objective of reducing fuel loading within wildland-urban interface zones. 

A couple of years after the areas are thinned, the bitterbrush is mowed using a 

small, tracked, all-season vehicle with a mower attachment. The mower makes a 

single pass over the entire unit (photo July 2007). Ecomap Section M242C -Eastern 

Cascades, Deschutes National Forest, Pacific Northwest Region.

Figure 4-11—Closeup of the soil structure in the unit. The forest floor is intact after 

mowing, with some soil displacement where the equipment turned.
37

Chapter 4

Figure 4-12—Vegetation: Ponderosa pine. The surface soil texture is gravelly 

sandy loam. The treatment was a green-tree thinning using a harvester/forwarder 

in 2007. The skid trail is rated as a class-1 disturbance based on shallow wheel 

tracks that are present, soil that has not been displaced, and compaction that is not 

evident (photo July 2007). Ecomap Section M242C - Eastern Cascades, Deschutes 

National Forest, Pacific Northwest Region.

Figure 4-13—Closeup of the soil structure from the skid trail in figure 4-12, showing 

no signs of increased compaction.
38

Soil-Disturbance Field Guide

Figure 4-14—Vegetation is dominated by grand-fir and Douglas-fir forests. The soils 

in the area are heavily influenced by a mantle of volcanic ash from Mount Mazama. 

The surface soil texture is silt loam. The treatment in this unit is part of an ongoing 

thinning project using cut-to-length with a harvester and forwarder. Soil impacts 

are within disturbance class 1. The combination of flat topography and operating 

on dry soil over surface litter reduces potential adverse impacts to soils (July 

2007). Ecomap Section M332G - Blue Mountains, Umatilla National Forest, Pacific 

Northwest Region.

Figure 4-15—A typical wheel track from the forwarder as it operates over surface 

litter.
39

Chapter 4

Figure 4-16—Vegetation is subalpine fir forest. The surface soil texture is loam. The 

unit was harvested in 2005 (photo August 2007) to remove insect mortality. The 

soil prescription was to operate over snow to reduce impacts to the soil. Prior to 

this treatment the area had not been entered since 1977. Ecomap Section M331A 

- Yellowstone Highlands, Shoshone National Forest, Rocky Mountain Region.

Figure 4-17—Closeup of the fine roots found throughout the soil sample of figure 

4-16.
40

Soil-Disturbance Field Guide

Figure 4-18—Forest vegetation is juniper-pinyon woodlands and saltbushgreasewood. The surface soil texture is loam. The treatment is to remove juniper 

with a small, tracked, rubber-tire tractor with a mulching head attachment. The 

treatment objective is for wildlife improvement and hazardous fuels reduction. The 

area was initially treated in the 1960s using two dozers dragging a chain. As the 

dozers worked cross slope the vegetation was removed, which created openings 

for wildlife movement. Now a less disturbing method uses a track-laying bobcat with 

mulching head. Mulch provides cover and reduces erosion. Treatment implemented 

in 2006 (photo June 2007). Ecomap Section 341C - Utah High Plateaus and 

Mountains, Dixie National Forest, Intermountain Region.

Figure 4-19—It is important to dig into the soil profile to check for signs of increased 

resistance and depth of soil compaction.
41

Chapter 4

Figure 4-20—Closeup of soil structure in the treated area below the mulch layer.

Figure 4-21—Closeup of the soil structure in the main skid trail.
42

Soil-Disturbance Field Guide

Figure 4-22—Vegetation is western spruce fir forest. The surface soil texture is 

gravelly clay loam. The unit is part of an insect salvage harvest of Engelmann 

spruce. The soil-prescription recommended use of preexisting trails and winter 

logging to reduce and avoid adverse impacts to soils. The logs were skidded over 

snow with rubber-tired skidders with chains and a D-5 track-laying dozer during 

the winter of 2006-2007. Compaction in the surface soil is only slightly greater than 

observed under natural condition. Ecomap Section M341C - Utah High Plateaus 

and Mountains, Dixie National Forest, Intermountain Region.
43

Chapter 4

Figure 4-23—Vegetation includes northern hardwoods on moraines and stratified 

ice-contact hills. The surface soil texture is fine sandy loam. This unit was part of 

a salvage logging prescription to remove trees damaged after a windstorm in 2006 

(photo September 2007). Ecomap Section 212H - Northern Great Lakes, Hiawatha 

National Forest, Eastern Region.
44

Soil-Disturbance Field Guide

Figure 4-24—Vegetation: Lodgepole pine. The surface soil texture is sandy loam. 

The treatment prescription was to thin the unit over snow during the winter of 

2005. Harvesting equipment included 3-wheeled shears and rubber-tired skidders. 

The soils are shallow to moderately deep and at high risk of erosion with removal 

of ground cover (photo August 2007). Ecomap Section M331H - North-Central 

Highlands and Rocky Mountain, Arapaho-Roosevelt National Forest, Rocky 

Mountain Region.

Figure 4-25—Closeup of the unit in figure 4-24 with no indications of compaction as 

a result of the winter-logging operation.
45

Chapter 4

Figure 4-26—Vegetation: Lodgepole pine. The surface soil texture is sandy loam. 

The thinning unit was conducted over snow during the winter of 2005. Equipment 

included 3-wheeled shears and rubber-tired skidders. Soils are shallow to 

moderately deep and at risk of accelerated erosion with loss of ground cover (photo 

August 2007). The low soil burn severity should not increase erosion because of 

limited areal extent and depth in the mineral soil. Ecomap Section M331H - NorthCentral Highlands and Rocky Mountain, Arapaho-Roosevelt National Forest, Rocky 

Mountain Region.

Figure 4-27—Several trees show signs of equipment operating in the area.
46

Soil-Disturbance Field Guide

Figure 4-28—Vegetation is silver fir, Douglas-fir, and fir/hemlock forest. The soils 

are dry for a significant portion of the summer due to rain-shadow effects on the 

east slope. Soils have low bulk density and organic-matter rich topsoil. The loss 

of topsoil from wind erosion is prevalent once soil cover is removed. Cold soils are 

common and less resilient to compaction. This unit has been entered previously 

and mechanical-equipment tracks are evident. Ecomap Section M242C - Eastern 

Cascades, Okanogan National Forest, Pacific Northwest Region. 
47

Chapter 4

Figure 4-29—Shallow ruts and increased compaction are visual attributes of 

previous mechanical activity.
48

Soil-Disturbance Field Guide

Figure 4-30—Vegetation: Mixed conifer. The soils are influenced by a mantle of 

volcanic ash from Mount Mazama. The surface soil texture is silty clay loam. The 

treatment was a commercial thinning with a tracked harvester and processor. The 

photo illustrates a single pass with equipment and minimal forest floor impacts. 

Ecomap Section M332G - Blue Mountains, Umatilla National Forest, Pacific 

Northwest Region. 

Figure 4-31—When conducting an assessment, compare the soil within the track 

and undisturbed area to assess the soil compaction. 
49

Chapter 4

Figure 4-32—Vegetation: Mixed conifer forest. Soils in this area are influenced by 

a mantle of volcanic ash from Mount Mazama. The surface soil texture is silt loam. 

The photograph illustrates legacy disturbance from a timber harvest approximately 

20 years ago. Visual indicators of class-1 disturbance in previously harvested units 

include vegetation composition and vigor, depth of forest floor, presence of stumps 

or cull decks, increased resistance to penetration with tile spade, and or platy 

soils. Ecomap Section M332G - Blue Mountains, Umatilla National Forest, Pacific 

Northwest Region. 

Figure 4-33—A closer inspection of the soil structure helps to observe the recovery 

of the soil. Areas with legacy disturbance can often be validated by reviewing older 

aerial photographs or stand records to pinpoint when an activity occurred.
50

Soil-Disturbance Field Guide

Figure 4-34—Vegetation: Mixed conifer forest. Soils in this area are influenced 

by a mantle of volcanic ash from Mount Mazama. The surface soil texture is silt 

loam. Legacy disturbance is identified in the field from previous timber harvest 

approximately 20 years ago. Visual indicators of class-1 disturbance include 

vegetation composition and vigor, depth of forest floor, presence of stumps or 

cull decks, increased resistance to penetration with tile spade, and or platy soils. 

Ecomap Section M332G - Blue Mountains, Umatilla National Forest, Pacific 

Northwest Region. 

Figure 4-35—Old stumps and logs indicate legacy disturbance.

Legacy disturbance is identified 

in the field thru visual indicators 

including:

• Vegetation composition and 

vigor.

• Depth of forest floor.

• Presence of stumps.

• Cull decks.

• Platy soils.

• Increased resistance.to 

penetration with tile spade.

Legacy disturbance
51

Chapter 4

Figure 4-36—Vegetation: Sitka spruce. The surface soil texture is a gravelly silt 

loam. Slight depressions are evident from yarding the trees across to the landing. 

Ecomap Section M 245C - Southern Alexander Archipelago, Tongass National 

Forest, Alaska Region. 

Figure 4-37—An older unit where logs were fully suspended as they were cable 

yarded across the narrow drainage to the landing area. Tongass National Forest, 

Alaska Region.

Indicators of forest floor 

disturbance:

• Ruts from yarding.

• Displaced soil.

• Vegetation type.

• Bare ground.

Indicators of forest 

floor disturbance
52

Soil-Disturbance Field Guide

Figure 4-38—Vegetation: Sitka spruce and western hemlock. Surface soil texture 

is a gravelly silt loam. A shovel-yarding technique is used on slopes less than 20 

percent. Slash mats are constructed to prevent rutting and support the weight of 

the shovel yarder (excavator). The soils have low bearing strength and adverse soil 

effects are avoided by combining a slash mat and equipment with a low (7 to 10 

pounds per square inch) static load. Ecomap Section M245C - Southern Alexander 

Archipelago, Tongass National Forest, Alaska Region.

Figure 4-39—Areas with heavy slash mats are reviewed by the soil scientist to 

assess impacts to the forest-recovery response time. Ecomap Section M245C - 

Southern Alexander Archipelago, Tongass National Forest, Alaska Region.
53

Chapter 5

The soil-disturbance class 2 is defined by the following 

characteristics:

Soil surface:

• Wheel tracks or depressions are evident in the mineral soil.

• Forest-floor layers partially intact or missing.

• Surface soil partially intact and may be mixed with subsoil. 

• Moderate soil burn severity. 

o Surface soil-water repellency increased compared to the 

preburn conditions.

o Black ash with the majority of the fuel consumed.

• Soil compaction is present in the mineral soil (down to about 12 

inches).

Observations of soil physical condition:

• Change in soil structure from granular to platy.

• Platy structure is generally continuous.

o Large roots may penetrate the platy structure; but fine and 

medium roots may not.

Soil-disturbance class 2 can be found throughout the landscape in 

both recent and older treatment units. Locations where one might 

expect to find class-2 disturbance is on main skid trails, flat terrain 

where there was more mechanized-equipment movement over the 

area, equipment turn locations, jackpot-burn piles with mixed fuels 

and soil, units with multiple operations occurring (e.g., thinning, 

mechanical-site preparation, prescribed burning), or units with large 

amounts of tree-volume removed.

Figure 5-1—Soil disturbance class 2.

• Wheel tracks or depressions 

are evident and moderately 

deep.

• Forest-floor layers are partially 

missing.

• Surface soil partially intact and 

maybe mixed with subsoil.

• Soil burn severity from 

prescribed fires is moderate 

(black ash evident and water 

repellency may be increased 

compared to preburn 

condition).

• Soil compaction is moderately 

deep (up to 12 inches).

• Soil structure is changed from 

undisturbed conditions and 

may be platy or massive.

CHAPTER 5

Defining SoilDisturbance Class 2

Soil-Disturbance Class 2
54

Soil-Disturbance Field Guide

Figures 5-2 through 5-24 provide photographic examples of soildisturbance class 2 from all Forest Service regions.

Figure 5-2—Vegetation: Lodgepole pine. The surface soil texture is sandy loam. 

The treatment prescription was to remove dead-and-dying lodgepole pine as a part 

of an insect salvage project. Extensive beetle infestation throughout the forest has 

resulted in a large volume of material being removed, leaving a clearcut appearance 

to the units. Potential adverse impacts to soils may occur from the number and 

density of skid trails, soil displacement, and amount of material left to maintain 

long-term soil productivity. Mechanized-equipment included a feller buncher and 

rubber-tired skidders. The unit was harvested in 2005-2006 (photo July 2007). 

Ecomap Section M331H - North-Central Highlands and Rocky Mountain, ArapahoRoosevelt National Forest, Rocky Mountain Region.

Figure 5-3—Vegetation: Lodgepole pine. The surface soil texture is sandy loam. 

This location was rated as class 2 after reviewing each soil attribute. The skid trail 

had increased soil compaction, and forest-floor layers were missing. ArapahoRoosevelt National Forest, Rocky Mountain Region.

• Forest floor layers are missing.

• Soil compaction.

• Soil structure changed from 

undisturbed.

Class 2
55

Chapter 5

Figure 5-4—A closeup of soil conditions within the skid trail from figure 5-3.

Figure 5-5—Vegetation: Longleaf pine and slash pine. Generally, the soils are 

poorly drained and deep throughout the unit. The surface soil texture is sandy 

loam. The treatment prescription was to reduce basal area to 50- to 60-basal 

feet per acre. The skid trails were placed on 70-foot centers to disperse activity 

throughout the unit. The equipment used included a feller buncher and rubber-tired 

skidders. The harvesting was completed 2-weeks prior to this photograph being 

taken (photo February 2007). Ecomap Section 232D - Florida Coastal Lowlands, 

Apalachicola National Forest, Eastern Region.
56

Soil-Disturbance Field Guide

Figure 5-6—Bare soil and ruts are visual indicators of class-2 soil disturbance.

Figure 5-7—A closeup of the weak soil structure of the sandy loam soil that is 

prevalent in the treatment units.

• Bare soil.

• Ruts.

Class 2
57

Chapter 5

Figure 5-8—Vegetation: Ponderosa pine. The surface soil textures include sandy 

loam and gravelly sandy loam. The treatment was implemented in 2004 to salvage 

dead trees from a 2004 wildfire and reforest the site. The main skid trail within the 

unit leads to the landing area (photo July 2007) and was subsoiled after it was used. 

Ecomap Section M242C - Eastern Cascades, Deschutes National Forest, Pacific 

Northwest Region.

Figure 5-9—Vegetation: Ponderosa pine. The surface soil texture is gravelly sandy 

loam. The treatment prescription included jackpot piling with an excavator to reduce 

fuel loading in the wildland-urban interface zone. Moderate soil-burn severity is 

evident with material consumed and black ash on surface. Piles burned during the 

winter of 2007 (photo July 2007). Ecomap Section M242C - Eastern Cascades, 

Deschutes National Forest, Pacific Northwest Region.

• Forest floor layers are missing.

• Soil compaction.

• Moderate soil burn severity.

Class 2
58

Soil-Disturbance Field Guide

Figure 5-10—Vegetation: Ponderosa pine, white fir, Douglas-fir, and some pinyon 

pine and juniper. The area burned during the 2000 Rodeo Chedeski wildfire 

(photo March 2007) and the surface soil remains charred. Visual evidence of soil 

morphological indicators of increased soil compaction is present. Ecomap Section 

M313A - White Mountain-San Francisco Peaks- Mogollon Rim, Apache-Sitgreaves 

National Forest, Southwestern Region.

Figure 5-11—Vegetation: Mixed conifer. The soils are influenced by a mantle 

of volcanic ash from Mount Mazama. The surface soil texture is silty clay loam. 

Wheel tracks are evident in the mineral soil and forest-floor layers are missing. 

The treatment prescription is for a commercial thin to improve stand health using 

a tracked processor for cut-to-length logging. Soil has high clay content and holds 

moisture. After one to two passes with the equipment there was visual evidence of 

class-2 soil disturbance, and the operation was temporarily suspended. Ecomap 

Section M332G - Blue Mountains, Umatilla National Forest, Pacific Northwest 

Region.

• Soil compaction.

• Ruts from equipment.

• Forest floor layers missing.

• Change in soil structure from 

undisturbed.

Visual indictors of 

Class 2
59

Chapter 5

Figure 5-12—Closeup of wheel tracks created from operating in suboptimal 

moisture conditions.

Figure 5-13—An example of the type and size of soil clod created from the 

equipment.
60

Soil-Disturbance Field Guide

Figure 5-14—Vegetation: Ponderosa pine, white fir, Douglas-fir, with areas of pinyon 

pine and juniper. The treatment prescription was to reduce fuel risks in forests 

adjacent to the wildland-urban interface by thinning. This main skid trail has high 

use by rubber-tired skidders as trees are yarded into the landing. Ecomap Section 

M313A - White Mountain-San Francisco Peaks-Mogollon Rim, Apache-Sitegraves 

National Forest, Southwestern Region.

Figure 5-15—Vegetation: Northern hardwoods. The surface soil texture is fine 

sandy loam. Ecomap Section 212H - Northern Great Lakes, Hiawatha National 

Forest, Eastern Region.
61

Chapter 5

Figure 5-16—Compaction-and-compression effects of equipment are observed in 

older skid trail. Loss of depth of A horizon is evident. 

Figure 5-17—Vegetation: Western spruce-fir forest. The surface soil texture is 

gravelly clay loam. A field test revealed increased resistance to penetration when 

digging with a tile spade in the skid trail. Differences between an undisturbed, 

single-equipment pass, and multiple-equipment pass trail were observed. The 

photo shows the difference in soil disturbance from the main skid and a single-pass 

skid trail adjacent to each other. Ecomap Section M341C - Utah High Plateaus and 

Mountains, Dixie National Forest, Intermountain Region.

Main

skid

Single

pass

• Age of impact and recovery.

• Degree of use: main skid versus 

single pass.

Skid trail differences 

due to:
62

Soil-Disturbance Field Guide

Figure 5-18—Signs of increased compaction in the main skid trail over the singlepass trail.

Figure 5-19—Vegetation: Western spruce-fir forest. The surface soil texture is 

gravelly clay loam. Increased resistance is apparent along with visual indicators of 

compaction deeper into the profile. Ecomap Section M341C - Utah High Plateaus 

and Mountains, Dixie National Forest, Intermountain Region.

Single pass skid trail under suboptimal conditions.
63

Chapter 5

Figure 5-20—Compacted soil found within skid trail.

Figure 5-21—Vegetation: Western spruce-fir forest with spruce dominating the 

overstory and subalpine fir in the understory. The surface soil texture is sandy loam. 

This unit was logged in 2004 to remove insect-damaged trees. Track-laying shears 

and rubber-tired skidders were used to yard logs. The soil prescription included 

avoiding slopes over 35 percent and subsoiling main skid trails and seeding with 

mountain brome after harvesting. The photo shows a remanent skid trail from 

the treatment conducted in 2004 (photo August 2007). Ecomap Section M331A - 

Yellowstone Highlands, Shoshone National Forest, Rocky Mountain Region.

• Compressed soil.

• Change in vegetation.

• Platy soils.

Class 2 indicators
64

Soil-Disturbance Field Guide

Figure 5-22—A closeup of the skid trail illustrates weak platy soil structure. 

Figure 5-23—Vegetation: Douglas-fir and western ponderosa forest. The surface 

soil texture is sandy loam. The treatment is a thinning operation conducted in 2006 

(2007 photo) using a ground-based harvester and forwarder. Ecomap Province 

M333B - Flathead Valley, Flathead National Forest, Northern Region.
65

Chapter 5

Figure 5-24—Closeup of forest-floor recovery in skid trail. Sample area is 

missing forest floor but small woody material and vegetation growth is apparent in 

surrounding area.

67

Chapter 6

The soil-disturbance class 3 is defined by the following 

characteristics:

Soil surface:

• Wheel tracks and depressions highly evident.

• Forest-floor layers are missing.

• Evidence of surface soil removal, gouging, and piling.

• The majority of surface soil has been displaced. Surface soil 

may be mixed with subsoil. Subsoil partially or totally exposed.

• High soil burn severity has the duff and litter layer completely 

consumed. The surface soil color may be reddish or orange in 

places and the surface soil is water repellent.

• Soil compaction is deep in the soil profile (greater than 12 

inches in depth).

Observations of soil physical conditions:

• Change in soil structure from granular structure to massive or 

platy structure greater than 12 inches in depth.

• Platy structure is continuous and roots do not penetrate the 

platy structure.

Landings, major skid trails, and temporary access roads often are 

classified as soil-disturbance class 3 due to equipment type and use. 

Soils with higher risk ratings due to high water tables, soil texture, 

slope steepness, or other conditions that increase the risk to the soil 

from equipment impacts should also be monitored. 

Operations that occur during the “shoulder” period of a season 

or under suboptimal conditions may develop areas of class-3 soil 

disturbance. Often the sale administrator is the best source of 

information on areas of potential concern. 

Figure 6-1 Soil-disturbance class 3.

• Wheel tracks or depressions 

are evident and moderately 

deep.

• Forest-floor layers are partially 

missing.

• Surface soil partially intact and 

maybe mixed with subsoil.

• Soil burn severity from 

prescribed fires is moderate 

(black ash evident and water 

repellency may be increased 

compared to preburn condition).

• Soil compaction is moderately 

deep (up to 12 inches).

• Soil structure is changed from 

undisturbed conditions and may 

be platy or massive.

CHAPTER 6

Defining SoilDisturbance Class 3

Soil-Disturbance Class 3
68

Soil-Disturbance Field Guide

Figures 6-2 through 6-24 provide photographic examples of class-3 

soil disturbance from all Forest Service regions.

Figure 6-2—Vegetation: Ponderosa pine. The surface soil texture is sandy loam. 

The treatment prescription was to remove roadside hazard trees as a part of a firesalvage sale. Ecomap Section M242C - Eastern Cascades, Deschutes National 

Forest, Pacific Northwest Region.

Figure 6-3—Closeup of soil structure from within the sample area on the skid trail.
69

Chapter 6

Figure 6-4—Vegetation: Sitka spruce and western hemlock. The surface soil 

texture is gravelly silt loam. Private timber lands are at high risk to mechanicalequipment impacts due to low load-bearing capacity of the soil. In remote areas 

aerial reconnaissance may help identify areas of concern. Ecomap Section M245C 

- Southern Alexander Archipelago, Alaska Region.

Figure 6-5—Extensive rutting can occur without slash mats to protect the soil. 

Highlighted areas show extensive 

rutting due to soils with low loadbearing capacity.
70

Soil-Disturbance Field Guide

Figure 6-6—Vegetation: Longleaf pine and slash pine with some areas of oak, gum, 

and cypress cover. The surface soil texture is sandy loam. Due to a high water table 

and poorly drained soils the soil prescription included installation of several water 

table monitoring wells and restricting the number of skid trails. This main skid trail 

was used to remove all the timber thereby concentrating the impacts to an area 

the forest could later restore. Ecomap Section 232D - Florida Coastal Lowlands, 

Apalachicola National Forest, Southern Region.

Figure 6-7—The platy soil structure is deep and continuous throughout the upper 

portion of the profile. 

Monitor units to 

assess:

• Degree of soil impacts.

• Extent of soil impacts.

• Duration of soil impacts.

• Distribution of soil impacts.
71

Chapter 6

Figure 6-8—Closeup of platy soil structure from the main skid trail. Notice that 

there are few roots within the soil. 

Figure 6-9—The soil risk rating for this area would identify the low load-bearing 

capacity of these soils due to a high water table. Deep ruts were created with a 

single equipment pass. Ecomap Section 232C - Atlantic Coastal Flatlands, Francis 

Marion and Sumter National Forest, Southern Region.
72

Soil-Disturbance Field Guide

Figure 6-10—Vegetation: Southern mixed forest and oak, hickory, and pine forest. 

Forest cover in this area is mainly longleaf pine and slash pine. The soils have a 

high water table with low load-bearing capacity. The surface soil texture is sandy 

loam. The treatment prescription for this active treatment area is a biomass removal 

of pine and hardwood to reduce fire risk (photo February 2007). Most of the 

treatment area had class-1 soil disturbance but higher risk areas (high water table) 

had deep ruts. Ecomap Section 232 C - Atlantic Coastal Flatlands, Francis Marion 

and Sumter National Forest, Southern Region.

Figure 6-11—Vegetation: Mixed conifer. The surface soil texture is sandy loam. This 

November 2006 photo shows recent thinning (within 2 months of when photo was 

taken) to improve stand health. Turning equipment often displaces soil and removes 

forest-floor cover. Ecomap Section M261B - Northern California Coast Ranges, 

Shasta-Trinity National Forest, Pacific Southwest Region.

Highlighted areas illustrate rut 

depth and soil displacement.
73

Chapter 6

Figure 6-12—The photo is a clearcut with extensive skid trails and surface-soil 

displacement. Ecomap Section M261B - Northern California Coast Ranges, ShastaTrinity National Forest, Pacific Southwest Region.

Figure 6-13—Vegetation: Jeffrey-pine forest. The surface soil texture is a gravelly 

sandy loam. The treatment prescription is biomass thinning to reduce the fuel 

hazard and create a defensible fuel break. The class-3 soil disturbance is in areas 

adjacent to the landing from heavy vehicle traffic during moist soil conditions, which 

causes compaction deep in the soil profile. Active timber sale (photo November 

2006). Ecomap Section M261G - Modoc Plateau, Lassen National Forest, Pacific 

Southwest Region. 

Class 3

Soil Displaced

No forest floor cover

Evidence of subsurface horizons

Class 1
74

Soil-Disturbance Field Guide

Figure 6-14—A main skid trail shows deep wheel tracks and depressions. The 

forest-floor layers are missing and soil compaction is deep.

Figure 6-15—Deep ruts and displaced soil from turning equipment is evident.
75

Chapter 6

Figure 6-16—Vegetation: Western spruce-fir forest. The surface soil texture is 

loam. This unit is part of an insect-salvage harvest of Engelmann spruce. Deep 

ruts and surface soil displacement from turning equipment reflect a class-3 soil 

disturbance. The soil scientist reviewed the area to explore options for yarding 

the cut trees to reduce and ameliorate effects to soils. Steep slopes add to the 

challenge of removing insect-salvage trees from the site. Ecomap Section M341C 

- Utah High Plateaus and Mountains, Dixie National Forest, Intermountain Region. 

Figure 6-17—Vegetation: Ponderosa pine, white fir, Douglas-fir, and some areas of 

pinyon pine and juniper. Rutted segment of skid trail has deep compaction and platy 

soil structure without roots (photo March 2007). Ecomap Section M313A - White 

Mountain-San Francisco Peaks-Mogollon Rim, Apache-Sitgreaves National Forest, 

Southwestern Region.

Soil-distubance class 3 

attributes:

• Soil structure is changed 

 from undisturbed conditions

 to platy or massive.
76

Soil-Disturbance Field Guide

Figure 6-18—Deeply compacted soils can be difficult to sample.

Figure 6-19—Compacted soil from main skid trail that may have been used during 

suboptimal moisture conditions.

Subsurface attributes:

• Compaction-deep.

• Platy structure.
77

Chapter 6

Figure 6-20—Vegetation: Sitka spruce and western hemlock. The surface soil 

texture is gravelly silt loam. On steep slopes, trees are downhill cable yarded to the 

landing. Proper deflection is necessary to avoid loss of soil cover. Soil prescriptions 

include partial suspension to minimize bare soil. Ecomap Section M245C - 

Southern Alexander Archipelago, Tongass National Forest, Alaska Region.

Figure 6-21—Vegetation: Lodgepole pine is dominate. The surface soil texture is 

sandy loam. This large unit was treated to remove insect-killed trees. The main 

skid trail has no soil cover, increased soil compaction, soil displacement, and 

some areas of soil rutting. The soil scientist reviewed the area after treatment 

and included mitigation measures to reduce compaction and the areal extent of 

skid trails, landings, and temporary roads in subsequent insect-salvage units. The 

treatment was implemented in 2005 (photo August 2007). Ecomap Section M331H - 

North-central Highlands and Rocky Mountain, Arapaho-Roosevelt National Forest, 

Rocky Mountain Region.

Class 3 on compacted 

access road and skid trail

Soil-distubance class 3 

attributes:

• Bare soil.

• Ruts.

• Topsoil displacement.

• Compaction-deep.

• Change in soil structure.
78

Soil-Disturbance Field Guide

Figure 6-22—Closeup of soil compaction within the skid trail.

Figure 6-23—Vegetation: Jack pine. The surface soil texture is sandy loam. 

After timber harvest in this 40-year-old jack pine unit with heavy mortality from 

insects, the unit was prepared for planting using a roller chopper that breaks up 

the remaining slash. Prior to planting, the area is scalped to create openings for 

reforestation. Areas of bare and gouged soil indicate class-3 soil disturbance. 

Ecomap Section 212H - Northern Great Lakes, Hiawatha National Forest, Eastern 

Region.
79

Chapter 6

Figure 6-24—Closeup of soil found within the treatment unit shown in figure 6-23.
80

Soil-Disturbance Field Guide
81

Chapter 7

Felling and yarding trees to a landing is often accomplished with 

mechanized equipment. It is during these operations that the 

risk of soil disturbance is greatest. Because of the design, some 

mechanized felling and yarding equipment is more prone to cause 

soil disturbance (in terms of extent and degree). However, all 

equipment can cause unwanted soil disturbance if it is operated 

improperly or beyond its capability. 

Volume of timber removed from a given stand, log size, residual 

slash, and soil conditions at time of operation, also play important 

roles in determining the amounts and effects of soil disturbance.

Post-harvest operations, such as mechanical-slash treatment and 

site preparation, also have the potential to generate varying degrees 

of soil disturbance. In some instances, these operations can create 

more soil disturbance than the original felling and yarding operations. 

Creation of soil disturbance also may be a management objective in 

some site-preparation operations.

When planning timber-harvest and post-harvest operations, land 

managers must not only consider the capabilities and limitations of 

specific equipment, but also the kinds of soils on which operations 

will occur. On low-risk soils, for example, managers may have a wider 

range of equipment choices and timing of operations than they do on 

high-risk soils.

Mechanized timber-harvesting technology has evolved over the 

years, and new machinery is available that provides cost-effective 

operations and limits soil disturbance. A prudent manager will 

select the best equipment for a particular job based on analysis of 

vegetation, topography, and soil characteristics as well as project 

objectives and economics. Figures 7-1 through 7-30 show the 

mechanized timber-harvesting equipment at work.

Common equipment and machinery used for felling include:

• Wheeled feller-buncher.

• Tracked feller-buncher.

• Excavator with harvesting head.

• Harvester.

A wheeled feller-buncher can have a boom-mounted head or—more 

commonly—a drive-to-tree configuration. Considerations for the soil 

prescription for the unit include the amount of ground surface covered 

by the equipment, the soil type and its risk rating within a proposed 

CHAPTER 7

Mechanical Equipment 

Used in Harvest and 

Post-Harvest 

Operations and Their 

Potential Soil Impacts

Harvest Equipment
82

Soil-Disturbance Field Guide

harvest unit, its inherent risk of damage by equipment, static and 

dynamic load effects, and slope limitations. Log size and volume to 

be removed also are important considerations.

Figure 7-1—A rubber-tired feller-buncher harvesting trees.

A tracked feller-buncher is similar to an excavator with a cutting 

head attached to the end of the boom, which provides lateral reach 

capabilities that enable the operator to fell and stack trees in bunches 

without having to drive to each one. Track-laying equipment generally 

has a lower static and dynamic load than wheel-based equipment. 

Depending on equipment size and reach capability, there is less soil 

disturbance. 

Tracked feller-bunchers come in many sizes. Choose the size of the 

equipment based on volume and size of timber to be removed, soil 

risk factors, and topographic characteristics. 

Figure 7-2—A tracked feller-buncher working at a single location. Once all trees are 

felled and bunched at this location, the machine will move to the next setting.

Tracked Feller-Buncher
83

Chapter 7

Harvesters generally are mounted on high-flotation, low-groundpressure tires. The number of wheels can vary. Harvesters have 

long booms with an attached cutting and processing head. As each 

stem is cut, it is delimbed and bucked into desired lengths. Logs are 

bunched for later retrieval and yarding to a landing by a forwarder. 

Figure 7-3—A rubber-tired harvester operating over rocky soils.

Figure 7-4—A harvester equipped with a processing head felling a tree.

Harvester
84

Soil-Disturbance Field Guide

Figure 7-5—A processing head is delimbing the tree prior to its being cut into 

lengths and picked up by a forwarder.

The forwarder is a self-propelled machine that is self-loading and 

designed to transport trees by carrying them completely off the 

ground. When combined with a harvester it is known as a cut-tolength system.

Forwarders often can be used to redistribute slash created by 

harvester operations onto trails to reduce soil impacts. 

Figure 7-6—A forwarder loading processed logs into the bunk. Note use of the 

slash mat that was created to reduce soil disturbance. 

Forwarder
85

Chapter 7

A three-wheeled feller-buncher commonly is used throughout the 

country. It is fast and maneuverable and can operate easily in 

densely stocked stands, but it has limitations on tree diameter. The 

machine must travel to each tree, and it can impact a large portion 

of a harvest unit. Soil concerns are related to the extent of ground 

surface impacted and forest-floor removal.

After a tree is felled, the whole tree is yarded into the landing area 

by a skidder. Limbs are removed at the landing where additional 

processing may occur. Soil-nutrient cycling must be considered when 

developing project design features.

Figure 7-7—Front view of a three-wheeled feller-buncher.

Figure 7-8—Fast and maneuverable, the three-wheeled feller-buncher can fell 

small-diameter trees quickly.

Three-Wheeled FellerBuncher
86

Soil-Disturbance Field Guide

Figure 7-9—Often a larger feller-buncher will work with the smaller, three-wheeled 

feller-buncher to fell the large-diameter trees in a treatment unit.

Skidders transport the cut trees to the landing area. There are 

several types of skidders, including:

• Grapple-skidder. This machine is used extensively to 

assemble and hold a load. It uses a hydraulic grapple or 

“pincher” to hold a turn of logs. One advantage of the grappleskidder is that one end of a turn of logs can be lifted free of 

the ground in order to avoid gouging and displacing surface 

soil. 

• Cable-skidder. This machine uses a main winch-cable and 

choker-set to assemble and hold a load. A cable-skidder is 

more versatile than a grapple-skidder, and the operator can 

“pull rope” to reach logs that cannot be driven to or that have 

unfavorable soil considerations.

• Tracked-skidder/bulldozer. This machine is mounted on tracks 

rather than on rubber tires. Most of these machines use a 

cable winch, and some have fair-leads to partially lift one end 

of the logs free of the ground.

Skidders
87

Chapter 7

Grapple-skidders vary in size. Notice the size difference between 

these two grapple-skidders. 

Figure 7-10—A small grapple-skidder can maneuver easily in tight areas.

Figure 7-11—This large grapple-skidder can bring a large load of trees into a 

landing area. Identify compaction or rutting concerns in areas with high risk-rated 

soils.
88

Soil-Disturbance Field Guide

Figure 7-12—A grapple-skidder with chains used for winter logging operations.

Trees are bundled by the feller-buncher and they are often stacked 

one behind another, similar to cars of a train.

Figure 7-13—Bundles of trees are ready to be moved into the landing area for 

sorting and processing.

Skidding Sequence
89

Chapter 7

Figure 7-14—The grapple-skidder moves into position and grabs an entire bundle of 

trees.

Figure 7-15—The bundle of trees is pulled into the landing area for further 

processing.
90

Soil-Disturbance Field Guide

Figure 7-16—Logs are delimbed, cut, and sorted prior to being trucked to the 

sawmill or cogeneration power plant. The landing size is an important consideration 

from both a safety and a soil-impact perspective.

Figure 7-17—At the landing site some of the logs and residues may be processed 

further. A chipper is often brought into the landing once all the saw-logs are 

removed. Small-diameter logs may be chipped. Limbs and branches may be 

redistributed on skid trails or placed in a pile for burning.
91

Chapter 7

Figure 7-18—Chip-van access into a unit was accomplished by removing the 

saw logs and then chipping the smaller logs. Once this process is completed, the 

landing access can be closed and the area subsoiled to improve infiltration.

Cable-yarding systems generally are used in areas with steep 

topography (slopes over 35 percent), or where other significant 

resource concerns may exist. Most cable systems used today are 

designed to either partially or totally suspend logs above the ground. 

Logs are attached to the cable using “chokers.”

There are many cable-logging systems (yarders, towers, carriages) 

in use today. Each system is designed to operate within certain 

topographic conditions and log-size parameters. These systems are 

not discussed in this guide.

While cable systems create little soil disturbance (approximately 3 to 

5 percent) within timber-harvest units, they do have the potential to 

create significant amounts of soil disturbance just below the landings. 

Often, such disturbance can concentrate water draining from the 

landing, which can cause unacceptable amounts of surface soil 

erosion and also trigger mass movement. In blind-lead situations, 

cable logging can generate large amounts of soil displacement where 

turns of logs (the number of logs hauled in one trip) create long, linear 

gouges. Depending on the particular system used, cable operations 

may require more roads and larger landings than some ground-based 

systems. 

Cable Yarding
92

Soil-Disturbance Field Guide

Figure 7-19—A cable-yarding operation is set up on a spur road harvesting trees on 

this steep slope.

Figure 7-20—Logs are brought up to the landing area with the small swing-yarder 

and then sorted and loaded onto log trucks.

Cable Yarding (cont)
93

Chapter 7

Shovel yarding uses an excavator body with a grapple-head 

attachment. This equipment generally is used on more gentle slopes. 

Often the shovel-yarder will lay down a slash mat to walk on as it 

yards the cut trees towards the landing.

Figure 7-21—Working on the sideslope, the shovel-yarder is moving the logs 

towards the landing. 

Figure 7-22—Shovel-yarding the felled trees towards the landing in Alaska.

Shovel Yarding
94

Soil-Disturbance Field Guide

The next step, after an area is harvested, is to ensure that the 

treatment objectives are met. Many forest-health and fuel-reduction 

prescriptions require follow-up treatments to reduce ladder fuel. 

Options available to eliminate ladder fuels depend on resource 

objectives not limited to soil and fuel prescriptions, air-quality 

constraints, slope, and cost. The fuel type and amount also factor into 

the eventual treatment design. Mechanical equipment (mowers and 

masticators) eliminate the fuel ladder and leave the residue onsite. 

Other treatments that remove the fuel from the treatment area include 

jackpot piling and burning of fuels, or broadcast burning.

One of the most common treatments has been the machine piling 

of slash using rubber-tired or tracked vehicles. These vehicles are 

often the same vehicles used in skidding operations. The slash piles 

are subsequently burned. If not done carefully, this operation has a 

high potential for creating undesirable amounts of soil disturbance, 

especially topsoil displacement. Pile burning can cause localized 

areas where the soil’s physical and chemical properties have been 

irreversibly altered. Machine slash piling can be done successfully if 

equipment is outfitted with brush rakes and operators use extreme 

care not to incorporate the mineral soil into the piles. 

Masticators and mowers commonly are used to reduce the size 

and vertical distribution of fuels. While the masticator and mower 

heads do not actually impact the ground, the excavator must travel 

to areas of fuel concentrations. This can create varying amounts 

of soil disturbance depending on how fuels are distributed within a 

treatment unit. The forest floor and topsoil easily can be displaced, 

especially where equipment makes turns. Hydro-ax and Tomahawk 

are examples of this equipment.

Figure 7-23—An excavator with a masticator attachment is shredding live 

vegetation.

Post-Harvest MechanicalTreatment Equipment
95

Chapter 7

Figure 7-24—The masticator-head grinds or flails woody vegetation into chips that 

provide soil cover.

The roller-chopper is a large drum pulled behind a skidder. The drum 

can be filled with water to add more weight, which helps to chop 

the woody material left onsite. The drum has several cutting blades 

that “chop” live vegetation and downed woody material. The residue 

is placed in contact with the ground surface, which helps facilitate 

decomposition and reduce the fire hazard. Most soil disturbance is 

generated by the vehicle towing the drum, although some severe 

compaction may occur directly under the cutting blades. The rollerchopper is used as a site-preparation technique in the Southern and 

Eastern Regions.

Figure 7-25—The front end of the skidder with a brush-rake attachment.

Skidder-Mounted 

Roller-Chopper
96

Soil-Disturbance Field Guide

Figure 7-26—A roller-chopper drum with blades designed to “chop” downed 

material.

Figure 7-27—A roller-chopper is breaking up forest residues on the Hiawatha 

National Forest after a salvage harvest.
97

Chapter 7

Figure 7-28—Chains have been attached to create openings and expose bare soil.

Many types of equipment have been developed and used over the 

years to restore soil disturbed by timber-harvest and post-harvest 

operations. While well intended, soil-restoration efforts can often 

produce unwanted soil disturbance if they are not designed to 

achieve specific objectives. 

Early efforts consisted of brush rakes attached to blades on either 

rubber-tired or tracked vehicles. Rock rippers also were used 

frequently to ameliorate effects of soil compaction. Neither piece 

of equipment produced the desired results and often created soil 

conditions worse than the ones being restored (furrows, dragging 

large stones and boulders to the surface, additional compaction, 

etc.).

In the 1980s and 1990s, soil cultivators, winged-subsoilers, and 

self-drafting winged-subsoilers were developed to improve results of 

soil-restoration projects. Soil cultivators were designed to be towed 

by small tracked vehicles. They could be lifted from the soil when 

stumps and boulders were encountered and, because of their small 

size, could be maneuvered into areas that could not be reached 

by larger pieces of equipment. Soil cultivators also resulted in less 

damage to residual trees. 

Soil Restoration 

Equipment
98

Soil-Disturbance Field Guide

Winged-subsoilers were an improvement over soil cultivators. They 

were designed to lift and shatter compacted soils without “plowing” 

them or dragging large rocks and boulders to the surface. They 

attach to the toolbar behind medium-to-large tracked vehicles. On 

self-drafting subsoilers, each shank is attached to an individual 

hydraulic mount that independently lifts the wing when obstructions, 

such as roots, stumps, and rocks, are encountered. The wings seek 

their maximum depth without additional weight. Again, this equipment 

produces desired results only when used properly under the correct 

soil conditions.

Figure 7-29—A modified excavator head to decompact landings and skid trails.

Figure 7-30—Subsoiling skid trail with a ripper shank on an excavator.
99

References

Curran, M.; Davis, I.; Mitchell, B. 2000. Silviculture prescription data collection field handbook: 

Interpretive guide for data collection, site stratification, and sensitivity evaluation for silviculture 

prescriptions. British Columbia Ministry of Forests Land Management Handbook 47. Victoria, BC, 

Canada: BC Ministry of Forests Research Program. 152 p.

Curran, M. P.; Maynard, D. G.; Heninger, R. L.; Terry, T. A.; Howes, S. W.; Stone, D. M.; Niemann, T.; 

Miller, R. E.; Powers, R. F. 2005. An adaptive management process for forest soil conservation. Forestry 

Chronicle. 81: 717-722. 

Curran, M. P.; Miller, R. E.; Howes, S. W.; Maynard, D. G.; Terry, T. A.; Heninger, R. L.; Niemann, T.; 

Van Rees, K.; Powers, R. F.; Schoenholtz, S. H. 2005. Progress towards more uniform assessment 

and reporting of soil disturbance for operations, research, and sustainability protocols. Forest Ecology 

Management. 220: 17-30.

Curran, M. P.; Maynard, D. G.; Heninger, R. L.; Terry, T. A.; Howes, S. W.; Stone, D.; Niemann, T.; 

Miller, R. E. 2007. Elements and rationale for a common approach to assessment and reporting of soil 

disturbance. Forestry Chronicle. 83: 852-866

Page-Dumroese, D.; Abbott, A. M., Rice, T. M. 2009. USDA Forest soil disturbance monitoring protocol, 

volume 1 - rapid assessment. FS-WO-82a. Moscow, ID: U.S. Department of Agriculture, Forest Service, 

Rocky Mountain Research Station. 29p.

Page-Dumroese, D.; Abbott, A. M., Rice, T. M. 2009. Forest soil disturbance monitoring protocol, volume 

2 - supplementary methods, statistics, and data collection. FS-WO-82b. Moscow, ID: U.S. Department of 

Agriculture, Forest Service. 64p.

Page-Dumroese, D; Jurgensen, M., Elliot, W., Rice, T. M., Nesser, J., Collins, T., Meurisse, R. 2000. Soil 

quality standards and guidelines for forest sustainability in northwestern North America. Forest Ecology 

Management. 138: 445-462. 

Powers, R. F.; Scott, D. A.; Sanchez, F. G.; Voldseth, R. A.; Page-Dumroese, D.; Elioff, J. D.; Stone, D. 

M. 2005. The North American long-term soil productivity experiment: Findings from the first decade of 

research. Forest Ecology Management. 220: 31-50.

Reynolds, K.M., Hessburg, P.F., Jensen, C.M., Miller, R.E., Meurisse, R.T., and Salter, R.B., (in press) 

Predicting risk of soil degradation associated with wildfire and ground-based logging. Soil Science 

Society of America Journal.

Soil Science Society of America. 2001. Glossary of soil science terms. Madison, WI: Soil Science 

Society of America. 

Scott, William. 2007. A soil disturbance classification system. Long-term site productivity paper #07-3/

October 2007. Weyerhaeuser Company. Western Timberlands R&D. 

U.S. Department of Agriculture, Forest Service. 1994. Ecological subregions of the United States: 

Section Descriptions. WO-WSA-5. Washington, DC: U.S. Department of Agriculture, Forest Service. 

Appendix

National Soil Disturbance Monitoring Form

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103

San Dimas Technology and Development Center (SDTDC) national publications are available on the 

Internet at: http://www.fs.fed.us/eng/pubs/

Forest Service and U.S. Department of the Interior, Bureau of Land Management employees also can 

view videos, CDs, and SDTDC individual project pages on their internal computer network at: http://fsweb.

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For additional information on the Soil-Disturbance Field Guide, contact Carolyn Napper at SDTDC. 

Phone: 909–599–1267 ext. 229. E-mail: cnapper@fs.fed.us