Western Juniper 

Field Guide: 

Asking the Right 

Questions to 

Select Appropriate 

Management Actions

U.S. Department of the Interior

U.S. Geological Survey

Circular 1321
Cover: Photograph taken by Richard F. Miller.
Western Juniper Field Guide: 

Asking the Right Questions to 

Select Appropriate 

Management Actions

By R.F. Miller, Oregon State University, J.D. Bates, T.J. 

Svejcar, F.B. Pierson, U.S. Department of Agriculture, and 

L.E. Eddleman, Oregon State University

This is contribution number 01 of the Sagebrush Steppe 

Treatment Evaluation Project (SageSTEP), supported by 

funds from the U.S. Joint Fire Science Program. Partial 

support for this guide was provided by U.S. Geological 

Survey Forest and Rangeland Ecosystem Science Center.

Circular 1321

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

For product and ordering information:

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does not imply endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from 

the individual copyright owners to reproduce any copyrighted materials contained within this report.

Suggested citation:

Miller, R.F., Bates, J.D., Svejcar, T.J., Pierson, F.B., and Eddleman, L.E., 2007, 

Western Juniper Field Guide: Asking the Right Questions to Select Appropriate 

Management Actions: U.S. Geological Survey Circular 1321, 61 p.

Edited and Designed by: Summer C. Olsen and Elizabeth A. Didier, Outreach 

Program Coordinators, Utah State University, Logan, Utah State University

All photographs in this guide were taken by Richard Miller unless otherwise 

noted.
Contents

Introduction.................................................................................1

Questions to be Addressed......................................................4

Setting Goals and Objectives...................................................6

Part I: Identifying the Ecological Site .....................................8

Part II: Current State of the Site ............................................24

Part III: Landscape Considerations ......................................41

Part IV: Selecting Appropriate Management 

Action and Treatment ................................................43

Post-Treatment Management................................................55

Appendix 1: Field Assessment Form....................................56

Appendix 2: Species Codes...................................................58

Glossary of Terms ....................................................................59
Figures

Figure 1. Juniper encroachment at Keystone Ranch, 

eastern Oregon, about 1890 and 1989 ................1

Figure 2. Current aerial distribution of western juniper 

(Juniperus occidentalis) in the western 

United States..........................................................3

Figure 3. Post-settlement Phase II western juniper 

stand ........................................................................7

Figure 4. Soil texture triangle...............................................9

Figure 5. A cemented ash layer at 12 in., compressing 

the juniper roots above the restrictive soil 

layer.........................................................................9

Figure 6. Basin big sagebrush/Thurber’s needlegrass 

plant association with a restrictive layer 

at 16-20 in., which limits tree rooting depth 

resulting in a loss of shrubs, grasses, 

and forbs ...............................................................10

Figure 7. Mountain big sagebrush/Idaho fescue plant 

association (Ecological site = Deep Loamy 

12-16 PZ) with moderately deep (>30 in.), 

well-drained, clay loam soils.............................10

Figure 8. A conceptual generalization of the potential 

for erosion and infiltration related to soil 

texture, slope, and the amount of gravel 

and pebbles on the surface ...............................11

Figure 9. Dead bitterbrush (PUTR) and big sagebrush 

(ARTR) remnants can be separated by 

differences in the wood; bitterbrush (top) is 

clear while sagebrush (bottom) has dark 

brown bands perpendicular to the annual 

growth rings..........................................................12

Figure 10. Diagnostic species that indicate warm-dry 

to cool-wet gradient............................................12
Figures—Continued

Figure 11. Crown of mountain big sagebrush (ARTRV) is 

generally flat-topped with inflorescence >1/2 

above vegetative crown, and Wyoming big 

sagebrush (ARTRW) with an uneven top and 

inflorescence <1/2 above vegetative crown...13

Figure 12. An 800-year-old western juniper tree with 

spreading rounded top and large lower limbs 

on sandy soils, Connely Hills, south-central 

Oregon...................................................................17

Figure 13. Old-growth western juniper with considerable 

dead branches, missing bark and lichen, 

occupying a shallow heavy clay soil on the 

Modoc Plateau in northern California..............17

Figure 14. Bark characteristics of three western 

juniper trees of different ages...........................18

Figure 15. Vigorous terminal and lateral leader growth 

(4-6 in.) on a sapling growing in the absence 

of competition from other trees ........................19

Figure 16. Mountain big sagebrush/bluebunch 

wheatgrass plant association with a stand 

of pre-settlement trees growing on shallow 

soils just below the ridgetop..............................19

Figure 17. Mountain big sagebrush/Idaho fescue 

plant association (Ecological site = Pumice 

10-12PZ) in central Oregon north of 

Christmas Valley ..................................................20

Figure 18. Relationship of time since fire and the

percent composition (dominance) of 

grasses, shrubs, and trees.................................22

Figure 19. Phase II mountain big sagebrush-bitterbrush/

Idaho fescue (Ecological site = Deep Loamy 

12-16 PZ) with a high level of structural 

diversity.................................................................23
Figures—Continued

Figure 20. Juniper leader growth, particularly of trees 

<3 m tall, is a good indicator of competition 

among trees..........................................................27

Figure 21. Three phases of woodland succession in 

mountain big sagebrush communities.............28

Figure 22. Conceptual model with estimated time 

periods from initial tree establishment (early 

Phase I) to minimum stocking adequate for 

Phase III, and estimated maximum potential 

for relative abundance and cover for 

stands developing on sites from high to low 

productivity...........................................................30

Figure 23. Relationship between age and tree height 

across mountain big sagebrush sites: tree 

height can be used as a coarse proxy to 

estimate stand age (multiply meters by 3.28

to convert to feet) ................................................31

Figure 24. A mixed-age stand of post-settlement trees ..31

Figure 25. Phase III site with an adequate density of 

deep-rooted grasses (Idaho Fescue, blue 

bunch wheatgrass, and Thurber’s 

needlegrass) to recover without seeding .......33

Figure 26. First growing season after a high-severity 

wildfire...................................................................34

Figure 27. Increasing juniper dominance on this site 

has led to increasing bare ground and 

mortality of understory species ........................34

Figure 28. This site lacks both woody and herbaceous 

understory to carry a fire and adequate 

desirable herbaceous species for 

restoration.............................................................35

Figure 29. A juniper-dominated site (Phase III) that has 

eroded to a restrictive layer (A horizon is 

gone) in the inter-canopy zone, resulting in 

accelerated runoff and erosion ........................37
Figures—Continued

Figure 30. Site with large, connected zones of bare 

ground in the inter-canopy.................................37

Figure 31. Mountain bluebirds consuming juniper 

berries early in the spring ..................................39

Figure 32. Tree cavity in the center of the trunk of an 

old-growth western juniper...............................39

Figure 33. Juniper thinning to 5 trees/acre (12/ha) 

(Ecological site = Deep Loamy 12-16PZ)..........45

Figure 34. Basin big sagebrush/bluebunch wheatgrassThurber’s plant association on a southwest 

aspect, 5,000 ft elevation, pre-treatment 

Phase III, tree canopy 25%, shrub cover 0.5%, 

herbaceous cover 2.5%, deep-rooted tall 

perennial bunchgrasses = 2/10 ft2....................47

Figure 35. Phases I and II mountain big sagebrush/

Idaho fescue (Ecological site = Deep North 

12-18 PZ), 4,500 ft elevation, and north aspect 

(background); basin big sagebrush/basin 

wildrye (foreground) (Phase I, but little rye 

prior to the fire) ....................................................49

Figure 36. A high-intensity wildfire was carried by 

the juniper canopy (35 to 40% cover) under 

extreme weather conditions, killing most 

of the understory, which included Idaho 

fescue, bluebunch wheatgrass, and 

Thurber’s needlegrass ........................................49

Figure 37. Prescribed fall burns in mountain big 

sagebrush and Idaho fescue in Phase II, 

8-12 native grasses/m2, and Phase III, 4-7 

plants/m2................................................................50

Figure 38. Aspen stand with dense sapling size (most 

of which are 40–60 years old) and western 

juniper in the understory ....................................51

Figure 39. Aspen regeneration following a prescribed 

fire to remove juniper..........................................51
Figures—Continued

Figure 40. Moderate-severity fire (notice needles on 

trees) where 80% of the native species in the 

understory survived; no seeding is required 

(Ecological site = Deep North 12-18PZ) ...........54

Figure 41. High-severity fire (notice no needles or bark 

remain on trees) where mortality of native 

herbaceous species was >80% ; 5 years 

after fire this site is dominated by introduced 

annual and biannual weeds; seeding 

required (Ecological site = Deep North 

12-18PZ).................................................................54

Tables

Table 1. Morphological characteristics of postsettlement (<150 years) and pre-settlement 

(>150 years) trees ................................................16

Table 2. Stand characteristics differentiating three 

transitional phases of woodland succession 

for several mountain big sagebrush 

associations, including Thurber’s needlegrass 

(maximum juniper cover 25-41%), Idaho 

fescue (maximum juniper cover 34-58%), 

and Columbia needlegrass (maximum 

juniper cover 60-75%) .........................................26

Keys

Key 1. Common sagebrush species associated 

with western juniper...........................................14

Key 2. Identifying ecological site and estimated 

fire return interval (FRI) ......................................21
Introduction

1

Introduction

Strong evidence indicates that western juniper has 

significantly expanded its range since the late 1800s by 

encroaching into landscapes once dominated by shrubs 

and herbaceous vegetation (fig. 1). Woodland expansion 

affects soil resources, plant community structure and 

composition, water, nutrient and fire cycles, forage 

production, wildlife habitat, and biodiversity. Goals 

of juniper management include an attempt to restore 

ecosystem function and a more balanced plant community 

that includes shrubs, grasses, and forbs, and to increase 

ecosystem resilience to disturbances. Developing a 

management strategy can be a difficult task due to 

uncertainty about how vegetation, soils, hydrologic 

function, and wildlife will respond to treatments. 

Figure 1. Juniper encroachment at Keystone Ranch, eastern 

Oregon, (a) about 1890 and (b) 1989. Photographs provided by 

Stu Garret.

(b)

(a)
Introduction

2

When developing a management strategy, the first 

and possibly most important step towards success is 

asking the right questions. Identifying the attributes of 

the area to be treated and selecting the right treatments

to be applied are of utmost importance. One must ask 

questions addressing the kind of site (that is, potential 

natural vegetation, soils, etc.), the current state of the site 

(that is, successional, hydrologic, etc.), what components 

need to be restored, how the management unit fits in with 

the overall landscape mosaic, and the long-term goals and 

objectives for the area or region. Keep in mind sagebrushsteppe vegetation is dynamic and management strategies 

must take into account multi-decade time frames. 

This guide provides a set of tools that will help field 

biologists, land managers, and private landowners conduct 

rapid qualitative field assessments that address the kind 

of site and its current state. These tools include a list of 

questions to be addressed and a series of photographs, 

keys, tables, and figures to help evaluate a site. 

Conducting this assessment will help prioritize sites to be 

treated, select the best treatment, and predict outcomes.

Success of a juniper management program may be 

greatly enhanced if an interdisciplinary team of local 

managers and resource specialists, who are experienced 

with vegetation, fuels, soils, hydrology, wildlife, and 

economic and sociological aspects of the local resource, 

use this guide to aid their decision-making.

Supporting Literature

This guide is closely linked to the synthesis 

publication Biology, Ecology, and Management of Western 

Juniper by Richard Miller and others (Oregon State 

University Agricultural Experiment Station Technical 

Bulletin 152, 2005). Please refer to this publication for 

more information and for literature cited. 
Introduction

3

Figure 2. Current aerial distribution of western juniper 

(Juniperus occidentalis) in the western United States.
Introduction

4

Questions to be Addressed

These questions are meant to provide a base or 

starting point for selecting appropriate management 

action. Because each management unit is unique, 

additional questions may need to be addressed or 

questions may need to be modified. The guide will focus 

on addressing the primary questions in Parts I, II, and III 

with information about the advantages and disadvantages 

of potential treatments in Part IV.

Setting Goals and Objectives

1. What are the desired ecological conditions or how 

should the site look in 5, 10, 20, or 50 years?

2. What vegetation changes need to occur to meet 

functional goals or habitat needs?

Answers to the questions in Parts I, II, and III will 

help managers determine feasible goals and objectives for 

a particular site. As a result, goals and objectives should 

be re-evaluated as these questions are answered.

Part I: Identifying the Ecological Site

3. What kind of soils are on the site?

4. How will the soils and physical features affect 

vegetation establishment and erosion?

5. What is the potential natural vegetation (PNV) or 

plant association?

6. Is there old-growth juniper on the site, and where is 

it growing?

7. Is the PNV woodland or shrub-steppe, and what is 

the fire return interval?

8. What was the past disturbance regime, and how did 

it influence the historic range of vegetation dynamics 

on the site?

9. What is the potential wildlife habitat value under 

PNV conditions?
Introduction

5

Part II: Current State of the Site

10. Clearly define the perceived problems: What are the 

factors affecting proper ecological function?

11. Is there recruitment of native understory species?

12. What is the stage of woodland succession (Phase I, 

II, or III) and age structure of trees?

13. What is the understory herbaceous composition?

14. What is the percentage of dead shrubs on the site, and 

what are the species?

15. What are the fuel characteristics, and what type of 

fire will the site support (ground fire or canopy fire)?

16. Are there signs of erosion and overland flow? What 

is the current capacity of the site to capture, store, 

and safely release water?

17. What is the current wildlife habitat suitability? How 

will treatment affect wildlife?

18. Are there social and/or economic concerns or issues 

tied to the site?

Part III: Landscape Considerations

19. What are the landscape spatial characteristics of the 

area to be treated with respect to patch size, edge, and 

connectedness?

20. Are there adjacent patches and what is the landscape 

composition?

21. How does the site connect to the landscape?

22. What are the current uses and management activities?

Part IV: Selecting Appropriate Management Action 

and Treatment

23. Factors that will influence treatment selection

24. Mechanical Treatments

25. Prescribed Fire

26. Cut and Burn Combinations

27. Chemical Treatments

28. Seeding

29. How will post-treatment management affect site 

conditions?
Setting Goals and Objectives

6

Setting Goals and Objectives

1. What are the desired1 ecological conditions 

or how should the site look in 5, 10, 20, or 50 

years?

Desired ecological conditions depend on 

management objectives, potential uses for the site, and 

ecological characteristics of the site, such as soil profiles 

and ecological site type. Managers need to identify 

conditions that are ecologically feasible on a given 

landscape and that will satisfy management objectives 

over the long term. Then they can determine if a treatment 

or series of treatments could help to achieve those results. 

Setting goals and objectives will often require 

participation by stakeholders, who may have differing 

or even conflicting ideas about the values that should 

be emphasized in juniper-dominated rangelands or the 

appropriate ecological condition of those lands. Natural 

disturbances and changes in environmental conditions 

also may affect the site, and management plans may need 

to be adjusted as a result. 

Because goals and objectives are influenced 

by many factors, they should be reevaluated as new 

information becomes available and adjusted accordingly. 

Answers to the questions that follow in this guide will 

provide information to managers that will help them 

in the ongoing process of setting appropriate goals and 

objectives for a particular site.

1

Words such as “desired”, “desirable”, and “best” are sometimes 

used to describe advantageous or suitable management approaches 

relative to management goals and objectives and in considerations 

of ecological responses of vegetation, soils, hydrologic function, and 

wildlife. These terms are used with recognition that many factors besides 

the evaluations described or cited in this manual may eventually come to 

bear in a decision-making process. In this context, these words should be 

viewed as relative terms only, not as explicit directives or judgments.
Goals & objectives

7

2. What vegetation changes need to occur to meet 

functional goals or habitat needs?

After a “desired condition” has been defined (for 

example, fig. 3), the next step is to identify the specific 

vegetation changes necessary for the site to meet 

functional goals, such as improved watershed health or 

wildlife habitat. For example, an increase in shrubs and 

herbaceous vegetation may be needed to increase vertical 

diversity for wildlife. Maintaining an open woodland 

canopy with a diverse understory may achieve these 

habitat goals. An increase in shrubs also could change 

structural diversity to affect fuels and maintain a desired 

fire regime. Erosion and sedimentation may be reduced 

with increasing perennial grass cover, and the ability of 

the site to capture and store water could be improved.

Figure 3. Post-settlement Phase II western juniper stand. A 

management objective for this site might be to maintain a diverse 

understory by reducing juniper dominance.
Identifying the Ecological Site

8

Part I: Identifying the Ecological Site

Ecological site and soil maps for the area should be 

obtained and used to help determine the proper ecological 

site description and soils. Maps should be verified during 

a site visit to ensure that the given descriptions match the 

site.

3. What kind of soils are on the site?

A soils map of the site or area will indicate what type 

of soils are present. 

Soil Texture (fig. 4): To determine soil texture of each 

horizon, add water to a healthy tablespoon of soil until 

you can roll it up in a ball without it leaving soil on your 

palm. Press the soil between your thumb and forefinger 

and attempt to form a ribbon.

•	 Good Ribbon: does not break and has few cracks = 

high clay content

•	 Medium Ribbon: ribbon cracks deeply and eventually 

breaks = moderate clay content

•	 Poor Ribbon: a ribbon cannot be formed or 

immediately breaks = low clay content

Add additional water and test for smoothness and 

grit. Gritty texture indicates sand.

Soil Depth: Soil depth is measured from the surface 

to the layer that retards root development:

Very shallow: <10 in.

Shallow: 10 to 20 in.

Moderately deep: 20 to 36 in.

Deep: 36 to 60 in.

Very deep: >60 in.

Restrictive soil layers increase below-ground 

competition. With increasing juniper dominance, 

herbaceous vegetation is likely to decrease on sites where 

there is a restrictive soil layer 16-18 in. beneath the 
Identifying the Ecological Site

9

surface. Soil layers (for example, cemented ash, heavy 

clay argillic layer, etc.) that restrict water movement also 

will influence water runoff on the site, and this should be 

considered before treatment (figs. 5-7).

Figure 5. A cemented ash layer at 12 in., compressing the 

juniper roots above the restrictive soil layer.

cemented 

ash layer

Figure 4. Soil texture triangle.
Identifying the Ecological Site

10

Figure 7. Mountain big sagebrush/Idaho fescue plant association

(Ecological site = Deep Loamy 12-16 PZ) with moderately deep 

(>30 in.), well-drained, clay loam soils. Western juniper roots are 

well distributed throughout the soil profile resulting in a loss of 

shrubs, but the Idaho fescue persists in the understory.

Figure 6. Basin big sagebrush/Thurber’s needlegrass plant 

association with a restrictive layer at 16-20 in., which limits tree 

rooting depth resulting in a loss of shrubs, grasses, and forbs.
Identifying the Ecological Site

11

4. How will the soils and physical features affect 

vegetation establishment and erosion?

Soil characteristics will influence the level of 

risk for erosion following treatment that involves tree 

removal. Soil surface stability, soil texture, soil depth, 

aggregate stability, patterns of bare ground, and evidence 

of rill and sheet erosion should be examined across the 

site. Treatments like prescribed fire may remove a large 

amount of vegetation, and the site may be vulnerable 

to erosion in the short term. Soil can be protected by 

methods such as cutting juniper and leaving slash on the 

ground. Another factor to consider is whether past erosion 

due to tree dominance has changed soil characteristics in 

ways that will affect the success of seeding (that is, has 

topsoil been lost?).

Erosion Potential

Low ------------------------------------------------------High

Infiltration Rates

High ------------------------------------------------------Low

Soil Texture

Coarse --------------------------------------------------Fine

% Slope

0 ------------------------------------------------------------>30

Amount of Rock and Pebbles on the Surface

100-------------------------------------------------------------0

Figure 8. A conceptual generalization of the potential for erosion 

and infiltration related to soil texture, slope, and the amount of 

gravel and pebbles on the surface.
Identifying the Ecological Site

12

5. What is the potential natural vegetation (PNV) 

or plant association?

•	 Which sagebrush species or subspecies is present on 

the site (key 1 and figs. 9-11; if Phase III, look for 

shrub skeletons on the site)?

•	 Is there evidence that pre-settlement trees occupied 

this site in the past (table 1 and key 2)?

•	 What are the diagnostic grass species?

Warm-Dry--------------------------------------------Cool-Wet

ARAR<ARTRW<ARTRT<ARTRV<ARTRV+PUTR<ARTRV+SYOR

ACTH<PSSPS<FEID<ACNE

Figure 9. Dead bitterbrush (PUTR) and big sagebrush (ARTR) 

remnants can be separated by differences in the wood; 

bitterbrush (top) is clear while sagebrush (bottom) has dark 

brown bands perpendicular to the annual growth rings.

Figure 10. Diagnostic species that indicate warm-dry to coolwet gradient (for definitions of plant codes see appendix 2).
Identifying the Ecological Site

13

Figure 11. Crown of (a) mountain big sagebrush (ARTRV) is 

generally flat-topped with inflorescence >1/2 above vegetative 

crown, and (b) Wyoming big sagebrush (ARTRW) with an uneven 

top and inflorescence <1/2 above vegetative crown.

(a)

(b)
Identifying the Ecological Site

14

Key 1. Common sagebrush species associated with 

western juniper (figs. 10–11). Key is based on persistent 

leaves.

1a. Mature shrubs <18 in. tall. 

2a. Flowers early summer, leaves broadly 

cuneate, with deep, well developed lobes, 

center lobe often buck-toothed (wider than 

space between two outer leaves), flower 

heads >3 mm wide...............early sagebrush

2b. Center lobe not buck-toothed, flower heads 

<3 mm wide...........................low sagebrush

1b. Mature shrubs >18 in. tall.

3a. Plant flat-crowned, flower stalks mostly 

>1/2 above vegetative shoots, leaves wedge 

shaped and tapered to base, leaves in 

water fluoresce bright bluish white under 

ultraviolet light ...... mountain big sagebrush

3b. Plant crowns uneven, flower stalks 

throughout the crown, usually <1/2 above 

crown, does not fluoresce bluish under 

ultraviolet light.

4a. Plants usually >3 ft. tall, wedgedshaped leaves ........ basin big sagebrush

4b. Plants usually <3 ft. tall, bell-shaped 

leaves ...............Wyoming big sagebrush
Identifying the Ecological Site

15

6. Is there old-growth juniper on the site, and 

where is it growing?

Old-growth western juniper trees provide valuable 

wildlife habitat, add structural and biological diversity 

to the landscape, and are part of the PNV. For these 

reasons, it is important to identify areas where oldgrowth occurs and carefully consider the appropriateness 

and consequences of any tree removal projects that 

might jeopardize the integrity of these sites (that is, 

thinning of younger trees where there is a potential for 

a stand-replacement fire). Old-growth western juniper is 

associated with a variety of soils, landforms, and plant 

associations, but typically grows in rock outcrops and 

soils that are shallow, rocky, and often high in clay or 

sand content, and in fine textured sedimentary soils. 

Old-growth stands commonly grow in areas where fuels 

accumulation is limited and stand-replacement or mixedseverity fires are infrequent. 

Questions to ask to determine if the site is or was an 

old-growth site:

•	 Are there trees on the site showing old-growth 

characteristics, or are the trees <150 years old 

(table 1)?

•	 Do the soils typically support persistent juniper 

woodlands, or do they have characteristics such as 

mollic horizons that developed under a grass or 

grass-shrub dominated vegetation?

•	 Does tree age structure suggest the site is relatively 

stable (limited recruitment), or are younger trees 

in-filling? 

•	 Are there large stumps or snags (>18 in. but often >24 

in. in diameter), often covered with char? 

•	 Are there large logs or branches lying on the site?
Identifying the Ecological Site

16

 Western Juniper Growth Form*

Characteristic Relatively Young Trees Relatively Old Trees

Crown shape Conical with pointed tip Flattened, rounded, or uneven topBranch structure Branches become progressively smaller from 

bottom to top of tree

In open stands, large branches near the base

Dead wood Little dead wood in the bole, few dead 

branches, little to no foliose lichen

Dead branches, bark missing, covered by a 

light green lichen

Bark (fig. 14) Flaky, relatively thin with limited or shallow 

vertical furrows

Thick, fibrous with well-developed vertical 

furrows

Leader growth Terminal leader growth in the upper 1/4 of 

the tree, usually >2 in. In open stands, leader growth >2 in. from bottom to top

Leader growth in the upper 1/4 of the tree 

usually <1 in.

*Growth form and morphological characteristics vary across trees and stands so usually several characteristics are required to separate 

young and old.

Table 1. Morphological characteristics of post-settlement (<150 years) and pre-settlement (>150 years) trees (figs. 12–15).
Identifying the Ecological Site

17

Figure 13. Old-growth western juniper with considerable dead 

branches, missing bark and lichen, occupying a shallow heavy 

clay soil on the Modoc Plateau in northern California. Plant 

association: western juniper/low sagebrush/Sandberg bluegrass 

(Ecological site = Juniper Tableland 10-14 PZ).

Figure 12. An 800-year-old western juniper tree with spreading 

rounded top and large lower limbs on sandy soils, Connely 

Hills, south-central Oregon. Plant association: western juniper/

bluebunch wheatgrass.
Identifying the Ecological Site

18

(b) At 152 years, bark layer is 

thickening and beginning to 

develop vertical furrows.

Figure 14. Bark characteristics of three western juniper trees of 

different ages.

(c) At 270 years, bark is 

thick and fibrous, with welldeveloped vertical furrows.

(a) At 75 years, bark is thin 

and flaky.
Identifying the Ecological Site

19

Figure 16. Mountain big sagebrush/bluebunch wheatgrass plant 

association with a stand of pre-settlement trees growing on 

shallow soils just below the ridgetop.

Figure 15. Vigorous terminal and lateral leader growth (4-6 in.) 

on a sapling growing in the absence of competition from other 

trees.
Identifying the Ecological Site

20

Figure 17. Mountain big sagebrush/Idaho fescue plant 

association (Ecological site = Pumice 10-12PZ) in central Oregon 

north of Christmas Valley. Large charred stumps on shallow 

to moderately deep soils indicate that a low density of widely 

scattered trees occupied the site prior to the late 1800s. Current 

tree density is 30-50 times greater.

7. Is the PNV woodland or shrub-steppe, and what 

is the fire return interval?

Key 2 can help identify the site as old-growth 

woodland (existing or following disturbance), tree-shrub 

savanna, or shrub steppe (figs. 16–17). The key also gives 

an estimated fire return interval (FRI) for the site. Return 

intervals in the key are meant only as a coarse proxy 

of the number of years between fires prior to Eurasian 

settlement if other documentation is not available.
Identifying the Ecological Site

21

Key 2. Identifying ecological site and estimated fire return interval (FRI).

1a. Potentially can grow big sagebrush

2a. Old live trees on the site (>150 years old).

3a. Old-growth tree canopy >20%..........................................................woodland........................... FRI >150 years

3b. Old-growth tree canopy <20%..........................................................tree shrub savanna

4a. Old trees on protected microsites* .......................................................................................... FRI <50 years

4b. Old trees scattered but on deeper soils ................................................................................... FRI 50-100 years

2b. No live old-growth trees on the site

5a. No large dead wood or stumps on site (>12 in. diameter fluted)......shrub steppe...................... FRI <50 years5b. Large dead wood present on the site.

6a. Density >22/acre.........................................................................woodland........................... FRI > 150 years

6b. Density <22/acre.........................................................................tree shrub savanna

7a. Relic wood on protected microsites ................................................................................. FRI <50 years

7b. Relic wood scattered but on deeper soils ......................................................................... FRI 50-100 years

1b. Potentially can grow low sagebrush (ARAR)

8a. ARAR >12 in. height, FEID or PSSPS diagnostic grass (go to 2a. and 2b.)8b. ARAR <12 in. height, POSA diagnostic grass

9a. No live old-growth or large relic wood.............................................low shrubland................... FRI >150 years9b. Old live trees or large relic wood (canopy rarely exceeds 20%).......tree-low shrub savanna.... FRI >150 years

*4a. Are old trees growing uniformly or randomly across the site, or do they grow on microsites (microtopography convex, rocky, etc.)? 

This is more common on south slopes. 
Identifying the Ecological Site

22

8. What was the past fire disturbance regime, 

and how did it influence the historic range of 

vegetation dynamics on the site?

The number of years between fire disturbance 

events (refer to key 2) will determine what kind of plant 

community will be most persistent on a site (fig. 18).

Figure 18. Relationship of time since fire and the percent composition (dominance) of grasses, shrubs, and trees. 

Years since last fire

Percent composition

120 80 140 60 40 160 200 100

80604020

0

100

Grassland Shrub steppe Woodland

Grasses Shrubs Juniper woodland

Shrubs

Grasses

Trees – High productive site

Trees – Low productive site
Identifying the Ecological Site

23

9. What is the potential wildlife habitat value 

under PNV conditions?

Would vegetation on the site and surrounding area 

support sensitive wildlife species (that is, sagebrush 

obligates) (fig. 19)?

•	 Is it important seasonal habitat (that is, key winter, 

nesting, brood-rearing habitat)?

•	 Is it an important link between other habitats?

•	 What vegetation layers (herb, shrub, tree) should be 

present and in what relative proportion?

Figure 19. Phase II mountain big sagebrush-bitterbrush/Idaho 

fescue (Ecological site = Deep Loamy 12-16 PZ) with a high 

level of structural diversity. Notice the leader growth on the 

juniper trees in the background, which will result in rapid canopy 

closure, loss of shrubs, and structural diversity. Sagebrush 

obligates, such as the green-tailed-towhee and Brewer’s 

sparrow, still use this site, but the sage thrasher, sage sparrow, 

and sage grouse are not likely to frequent such sites.
Current State of the Site

24

Part II: Current State of the Site

10. Clearly define the perceived problems: What are 

the factors affecting proper ecological function?

An important attribute that affects proper ecological 

function is vegetation structure, specifically the amount, 

type, and distribution of plant ground cover. If the site 

is not functional with respect to water and nutrient 

cycles or soil or biotic integrity, physical conditions 

that are connected to the problem need to be identified. 

Site condition should be evaluated to determine if an 

imbalance in plant community composition, a lack of 

structural diversity in the vegetation community, or a 

high proportion of bare ground are contributing factors. If 

proper ecological function or biodiversity are at risk due 

to encroachment or increasing density of junipers, the best 

way to maintain or restore hydrologic function and soil 

or biotic integrity is to implement treatments that reduce 

juniper dominance and ensure recovery or maintenance of 

understory vegetation on the site. Additional factors that 

might be weighed in treatment decisions include multiple 

management objectives (for example, wildlife habitat and 

fuels management), economic costs/benefits, and social 

values.

11. Is there recruitment of native understory species?

•	 Are there different size sagebrush or bitterbrush 

indicating recruitment?

•	 Are there perennial grass seedlings or small, 

young-looking bunches?

The presence of established seedlings and young 

plants indicates ongoing recruitment of species, while 

presence of healthy mature, seed-producing plants 

indicates that the potential for seed production still persists 

on the site. If old, decadent, or dying plants are common 

and no signs of active reproduction/recruitment are found, 

species are likely on the decline and the site may require 

restoration. 
Current State of the Site

25

12. What is the stage of woodland succession 

(Phase I, II, or III) and age structure of trees?

The stage of woodland development can influence 

the type of treatment selected, follow-up treatments 

and management, understory competition, seed pools, 

and vegetation response following management. There 

are three transitional phases of juniper woodland 

development: 

•	 Phase I – trees are present but shrubs and herbs are 

the dominant vegetation that influence ecological 

processes (hydrologic, nutrient, and energy cycles) on 

the site;

•	 Phase II – trees are co-dominant with shrubs and 

herbs, and all three vegetation layers influence 

ecological processes on the site;

•	 Phase III – trees are the dominant vegetation and the 

primary plant layer influencing ecological processes 

on the site.

Stand characteristics can be used to classify 

woodland development according to these phases. Early 

indicators to identify juniper domination of a site include 

shrub canopy mortality and reduction of leader growth 

on juniper saplings (<10 ft tall). The number of years 

between initial juniper encroachment and stand closure 

is largely determined by the rate of establishment and 

climate conditions (figs. 20–24 and table 2). 
Current State of the Site

26

Phases of Juniper Woodland Succession

Characteristics

(post-settlement stands)

Phase I

(early)

Phase II

(mid)

Phase III

(late)

Tree canopy

(% of maximum potential)

Open, actively expanding

<10%

Actively expanding

10 to 30%

Expansion nearly stabilized

>30%

Leader growth

(dominant trees) (cm/yr)

terminal >10

lateral >10

terminal >10

lateral 5 to >10

terminal >10

lateral <5

Crown lift*

(dominant trees) Absent Absent Lower limbs dying or dead where tree canopy >40%

Potential berry production Low Moderate to high Low to near absent

Tree recruitment Active Active Limited

Leader growth

(understory trees) (cm/yr)

terminal >10

lateral >8

terminal 5 to >10

lateral 2 to >8

terminal <5

lateral <2

Shrub layer Intact Nearly intact to significant thinning >75% dead

Table 2. Stand characteristics differentiating three transitional phases of woodland succession for several mountain big sagebrush 

associations, including Thurber’s needlegrass (maximum juniper cover 25-41%), Idaho fescue (maximum juniper cover 34-58%), and Columbia needlegrass (maximum juniper cover 60-75%) .

*Crown lift is the mortality of lower tree limbs, usually due to shading by neighboring trees.
Current State of the Site

27

(a) Leader growth is between 10-15 cm (4-6 in.), Phases I and early II.

(c) Leader growth is <5 cm (2 in.), late Phase II and Phase III.

(b) Leader growth is 5-10 cm (2-4 in.), Phase II.

Figure 20. Juniper leader growth, particularly of trees <3 m tall, 

is a good indicator of competition among trees.
Current State of the Site

28

Figure 21. Three phases of woodland succession in mountain 

big sagebrush communities.

(a) Subordinate - Phase I

Plant association: mountain big sagebrush/Idaho fescue

Ecological site: Deep Loamy 12-16 PZ

Maximum potential tree cover: 40-60%

Current tree cover: <5%, shrub cover: 40% 

(b) Co-dominant - Phase II

Plant association: mountain big sagebrush/Thurber’s 

needlegrass

Maximum potential tree cover: 25-35%

Current tree cover: 5-10%, shrub cover: 15-20%
Current State of the Site

29

(d) Dominant - Phase III on a south aspect with a soil restrictive 

layer at 41-46 cm (16-18 in.).

Plant association: mountain big sagebrush/Thurber’s 

needlegrass

Ecological site: Juniper South 12-16 PZ

Maximum potential tree cover: 25-35%

Current tree cover: 25%, shrub cover: 0%

(c) Dominant - Phase III on a north aspect and deep (for 

example, >61 cm or 24 in.) well-drained soil.

Plant association: mountain big sagebrush/Idaho fescue

Ecological site: Deep North 12-18 PZ

Maximum potential tree cover: 40-60%
Current State of the Site

30

Figure 22. Conceptual model with estimated time periods from initial tree establishment (early Phase I) to minimum stocking adequate for Phase III, and estimated maximum potential for relative abundance and cover for stands developing on sites from high to low productivity (from Johnson, D.D. and R.F. Miller, 2006, Structure and development of expanding western juniper woodlands as influenced by two topographic variables. Forest Ecology and Management 229:7-15.).
Current State of the Site

31

Figure 24. A mixed-age stand of post-settlement trees. For scale, 

the 42-year-old tree is 2.3 m (7.5 ft ) tall.

Figure 23. Relationship between age and tree height across 

mountain big sagebrush sites: tree height can be used as a 

coarse proxy to estimate stand age (multiply meters by 3.28 to 

convert to feet).

75yrs

2.3m

35yrs

42yrs

27yrs

24yrs

84yrs

0

2

4

6

8

10

12

14

16

0 20 40 60 80 100 120

Tree Age (yrs)

Height (m)
Current State of the Site

32

13. What is the herbaceous composition?

•	 Is the density of tall perennial bunchgrasses adequate 

for restoration or should the site be seeded?

•	 What are the desirable species and how abundant are 

they?

•	 Is there evidence of reproductive effort for the 

desirable species?

•	 Are there young, deep-rooted perennial grasses?

•	 Are there threatened or endangered plant species on 

the site?

•	 Are invasive plant species present, or are seed sources 

near the site?

Pre-treatment understory composition has a large 

influence on the success or failure of efforts to restore 

plant communities by removing or thinning western 

juniper. How does current understory composition 

compare to the desired understory composition? 

Potential impacts of natural disturbance or treatment 

implementation on the understory should be considered. 

Does pre-treatment understory composition indicate that 

the site will recover following treatment? 

Limited research suggests that if at least two deeprooted perennial grasses (that is, Idaho fescue, bluebunch 

wheatgrass, needlegrass) per 1 m2

 (10 ft2) persist on the 

site, recovery of understory vegetation after treatment 

is possible, although this is likely to vary with soil 

type, precipitation regime, and method of treatment 

(fig. 25). If perennial grasses and forbs are not present, 

or if the existing plants are in such poor condition that 

they are unlikely to survive the treatment, seeding may 

be necessary. The presence of an invasive species seed 

source, like cheatgrass, also may increase the need to 

quickly seed the site (fig. 26).
Current State of the Site

33

Invasive Plant Species

If undesirable plants, such as non-native weeds, 

are present on the site or present on adjacent sites, 

controlling their establishment and spread should be part 

of the management plan. Weed invasion is more likely 

on low-elevation and dry sites. Hot fires where woody 

vegetation is dense also will increase the potential of 

weed invasion. Several studies have shown that annual 

weeds can increase dramatically immediately after a 

tree-removal project, but often decrease over a period of 

years as native perennials are established on the site. A 

careful evaluation of expected desirable plant response 

based on the perennial grasses and forbs existing on the 

site prior to treatment, along with clear alternative plans 

in the event that native understory recovery does not occur 

as expected, will increase the likelihood of successful 

restoration (fig. 26).

Figure 25. Phase III site with an adequate density of deeprooted grasses (Idaho Fescue, blue bunch wheatgrass, and 

Thurber’s needlegrass) to recover without seeding. Although 

fires in Phase III are infrequent, when wildfires do occur they are 

usually high severity resulting in greater mortality of deep-rooted 

perennial grasses (Ecological site = Deep Loamy 12-16PZ).
Current State of the Site

34

14. What is the percentage of dead shrubs on the 

site, and what are the species (fig. 27)?

Figure 27. Increasing juniper dominance on this site has led 

to increasing bare ground and mortality of understory species. 

Note the dead shrub skeletons. Site is in the early stages of 

Phase III.

Figure 26. First growing season after a high-severity wildfire. 

This south aspect site burned during a hot windy August day, 

resulting in high mortality of an already depleted stand of deeprooted perennial grasses and establishment of cheatgrass.
Current State of the Site

35

15. What are the fuel characteristics, and what 

type of fire will the site support (ground fire or 

canopy fire)?

•	 What type of fire will the site support, and will it burn 

under moderate or extreme conditions (fig. 28)?

An assessment of fuel characteristics is necessary for 

selecting management treatments and understanding how 

natural processes (for example, water, nutrient, fire cycles) 

may be affected by treatment or no management action. 

Is herbaceous vegetation in the understory providing fine 

fuels? Does the amount of shrubs and small trees in the 

plant community provide sufficient ladder fuels to carry 

a fire into tree canopies? Does the site have a closed tree 

canopy that is likely to carry the fire throughout the entire 

site or is there an open canopy that may result in a mosaic 

fire pattern?

Figure 28. This site lacks both woody and herbaceous 

understory to carry a fire and adequate desirable herbaceous 

species for restoration. This Phase III woodland will burn under 

severe conditions and introduced annual weeds will dominate 

the site following fire.
Current State of the Site

36

16. Are there signs of erosion and overland flow? 

What is the current capacity of the site to 

capture, store, and safely release water (derived 

from Interpreting Indicators of Rangeland 

Health2

)?

•	 Are there rills on the site that suggest an accelerated 

loss of soil and water?

•	 What are the water flow patterns, and how do they 

relate to ground vegetation cover?

Sites with large amounts of bare ground, relatively 

fine-textured soils, steeper slopes and potential for 

high-intensity thundershowers are susceptible to erosion. 

Runoff can move continuously through connected intercanopy zones of bare ground, and accelerated erosion 

is likely to be a problem on sites with these conditions. 

Soil in bare inter-canopy zones also is more susceptible 

to raindrop impact, soil crusting, decreased infiltration, 

and increased erosion due to lack of protection from 

vegetation. 

A thick overstory of juniper also can reduce soilwater-capture and infiltration by limiting the amount of 

precipitation that reaches the ground. Research indicates 

that when juniper dominance is reduced, resulting in an 

increase in herbaceous cover on sites with relatively finetextured soils, runoff and soil erosion decrease. Leaving 

juniper debris on the ground after mechanical treatments 

can intercept runoff and increase infiltration, as well as 

reduce evaporative loss of soil water. Signs of erosion 

may include rills, gullies, plant pedestals or terracettes, 

and large amounts of plant litter movement by water. 

Water flow patterns should be examined to determine if 

they indicate erosion (figs. 29-30).

2

Pellant, M. P. Shaver, D. Pyke and J. Herrick. 2005. Interpreting 

Indicators of Rangeland Health. Technical Reference 1734-6. Available 

online at http://fresc.usgs.gov/products/papers/1385_Pellant.pdf
Current State of the Site

37

Figure 30. Site with large, connected zones of bare ground in the 

inter-canopy.

Figure 29. A juniper-dominated site (Phase III) that has eroded 

to a restrictive layer (A horizon is gone) in the inter-canopy zone, 

resulting in accelerated runoff and erosion.
Current State of the Site

38

17. What is the current wildlife habitat suitability? 

How will treatment affect wildlife?

The habitat suitability will largely be determined 

by the composition and structure of vegetation at the 

community and landscape level. The spatial arrangement 

and connectedness of plant community patches are an 

important attribute in determining habitat suitability. 

Increasing juniper dominance at the community 

and landscape levels results in a decline in landscape 

and plant community diversity, which reduces wildlife 

abundance and diversity. Research has not identified any 

wildlife species that are obligates to closed (Phase III) 

juniper woodlands. However, old-growth and open juniper 

woodlands provide important habitat. Following are some 

habitat suitability conditions to consider when planning 

treatments.

•	 Is the site in a transitional phase that will alter 

structure and composition, resulting in a change in 

habitat stability?

•	 Juniper berries (female cones) are an important winter 

food source for a variety of birds, so maintaining a 

woodland component on the site can be beneficial 

(fig. 31). However, berry production declines as 

woodlands transition toward Phase III. 

•	 Bird species diversity and richness are greatest in 

Phases I and II (structural diversity of vegetation is 

important). 

•	 Greater numbers of tree cavity nesting birds are 

usually found in old-growth juniper woodlands.

•	 Mule deer use juniper stands as winter cover. Dense 

stands with shrubs/trees more than 5 ft tall provide 

optimal thermal cover but minimal food resources. 

•	 Decreases in shrubs due to woodland development 

results in decreased browse available for deer and 

other species. 

•	 Decreases in grasses reduce seed production and 

seeds eaten by small mammals and birds.
Current State of the Site

39

Figure 31. Mountain bluebirds consuming juniper berries early in 

the spring. Photograph by Rick Vetter.

Figure 32. Tree cavity in the center of the trunk of an old-growth 

western juniper. Old stands of trees have a relatively high density 

of cavity nesting birds. Photograph by Rick Vetter.

Treatments such as prescribed fire may have 

immediate negative impacts on certain species, such as 

shrub-nesting birds, but may be important in limiting 

juniper encroachment and maintaining optimal conditions 

for wildlife across the landscape in the long term.
Current State of the Site

40

18. Are there social and/or economic concerns or 

issues tied to the site?

Treatment of a site may not be feasible or practical 

due to ecological, economic, or sociological reasons. 

Treatment can be expensive, especially for Phase III 

woodlands, because of the inputs needed to return the site 

to a desired condition, and achieving desired results can 

be difficult. 

Conducting an economic evaluation may assist a 

manager in considering the long-term environmental 

consequences. Not all benefits and costs involved with 

these treatments are quantifiable or have dollar values 

attached to them. In those cases, a social benefit-cost 

analysis can be used to identify both the quantifiable 

and non-quantifiable benefits and costs. Where dollar 

values cannot be determined, economic principles may be 

applied to assist in allocating resources, such as treatment 

funds and labor. 

Treating a stand in Phase I may make more economic 

sense than waiting until Phase II even though the apparent 

immediate benefits may be lower. Seeding can be 

risky on dry sites, where a high amount of erosion has 

occurred, where safe sites are not plentiful for seedling 

establishment, or where non-native invasive species are 

likely to quickly occupy the site. Removal of trees on 

sites where treatments are not likely to succeed may 

cause greater ecological damage (for example, increased 

bare ground, erosion and nutrient loss, increased weed 

invasion, and loss of wildlife habitat) than no management 

action. 

Social issues to consider include wildland urban 

interface, values, perceived ecological impacts of different 

treatments, concerns for sensitive wildlife and plant 

species, recreation, development, archeological sites, etc.
Landscape Considerations

41

Part III: Landscape Considerations

19. What are the landscape spatial characteristics of 

the area to be treated with respect to patch3 size, 

edge, and connectedness?

Patch size: Treatment patch size is especially 

important to consider in relation to use by wildlife and 

livestock. Is the treatment size large enough to provide 

suitable conditions for wildlife species of concern? Is 

the treatment area so small that post-treatment overuse/

overgrazing by domestic and/or wild herbivores will 

threaten the survival of newly established understory 

plants or aspen? Even with adequate forage in the area, 

the palatability of plants for several seasons after a fire 

will be higher than before, and burned patches will tend 

to attract wild and domestic herbivores. Is the patch 

size large enough to justify post-treatment management 

changes, such as no grazing for 1 or 2 years before or 

after the burn? If the treatment site is a relatively small 

area within a much larger pasture, resting the entire 

pasture from grazing may not be economically feasible 

or socially acceptable. Doing so may result in more 

ecological harm at other sites as grazing pressure is 

moved to those locations (on either public or private land).

Edge: Will treatment create sufficient edge habitat 

that is valuable to wildlife? How will the spatial 

distribution of edge influence seed rain from adjacent 

unburned sites onto the treated site?

Connectivity: Is the connectivity of various 

patches important for wildlife species of concern? 

Patch connectivity can influence wildlife movement, 

recruitment, predation, etc. How does distance to 

similar patches or patches of concern influence wildlife 

movement, recruitment, predation, etc.?

3

A patch is defined here as an assemblage of plant species growing on 

a contiguous area forming a plant community with a defined boundary 

and may represent different successional states within an ecological site.
Landscape Considerations

42

20. Are there adjacent patches and what is the 

landscape composition?

Considering how the site is connected to other 

patches and the distance to similar patches, will treatment 

enhance wildlife habitat and watershed health? Do 

corridors exist between patches for wildlife movement? 

Does landscape patch composition provide diverse habitat 

for a variety of wildlife in all seasons? How will treatment 

affect biodiversity at the landscape scale?

21. How does the site connect to the landscape? 

Landscapes are composed of patches of different 

plant communities and habitats. Management of 

landscapes rather than individual stands includes 

consideration of patch composition, spatial arrangement, 

size, and connectivity. Consideration of which patches 

and how much to treat are important. Portions of these 

landscapes may provide key habitat for certain species 

(that is, sagebrush cover for sagebrush obligates or deer 

fawning). The initial removal of sagebrush as trees are 

removed may be necessary to maintain the long-term 

integrity of these important habitats. An alternative would 

be to treat a percentage of these key habitats, saving the 

remaining proportion for treatment at a later date when 

the treated areas have recovered. Maintaining a mosaic 

of patches of different successional stages also may be 

desirable for maximizing habitat diversity, reducing fuel 

continuity, increasing snow capture, etc. 

22. What are the current uses and management 

activities?

It is important to consider how a treatment will affect 

current use and management activities in the short and 

long term. If the immediate treatment negatively affects 

wildlife habitat or livestock grazing, how long will it take 

to realize benefits of treatment? Are there other areas 

available for these uses during the short term? If the 

treatment location is within a larger area being managed 

for fuels reduction, how will the treatment affect this?
Selecting Appropriate Management Action and Treatment

43

Part IV: Selecting Appropriate 

Management Action and Treatment

Woodland structure within and across woodland 

successional phases will be determined by the type, 

frequency, and intensity of disturbance. The best 

management actions will be determined by the 

composition of all vegetation layers of the woodland, 

economic feasibility, and social acceptability.

23. Factors that will influence treatment selection:

•	 Fuel composition and structure » Tree sizes » Number of trees per acre » Dead plant material » Herbaceous plant size and density » Shrub size and density

•	 Plant composition » Abundance of desirable species » Desirable fire-sensitive species (for example, 

sagebrush, bitterbrush)

» Invasive species » Woodland phase

•	 Ecological site – risk and restoration potential

•	 Sensitive species (for example, sage grouse)

•	 Objectives

•	 Size of area to be treated

•	 Liability and proximity to other plant communities 

(for example, forest)

•	 Cost and resources

•	 Social acceptability
Selecting Appropriate Management Action and Treatment

44

24. Mechanical Treatments

Mechanical treatments are often used to reduce 

juniper dominance in Phases II and III woodlands. In 

general, the benefits of mechanical removal of juniper 

include flexibility in timing of treatment application and 

the ability to precisely control treatment boundaries or 

trees targeted (for example, old-growth trees can be left 

as wildlife habitat). With mechanical treatments, the 

impact to understory vegetation is often minimal. Cut 

trees or slash also can be left on the site to control erosion 

and provide safe sites for seedling establishment, or to 

enhance wildlife habitat.

Disadvantages are that mechanical methods often 

require follow-up treatment for small trees that were not 

initially removed, fuel loads can be increased by leaving 

cut trees/slash on the site, and treatment can be difficult to 

implement and costly when working in areas with rough 

terrain. Large amounts of slash in late Phase II and Phase 

III create a fire hazard for a minimum of 2 years and can 

limit the mobility of large herbivores (domestic and wild). 

In addition, heavy slash, which may kill desirable plants 

by shading, will provide open sites for establishment of 

introduced species.

Patience may be required in regards to treatment 

response when using mechanical treatments for 

restoration. A delayed understory response is common. 

Understory response in the first year after treatment is 

unpredictable, and it may take several years for understory 

plants to fully occupy the treated area.
Selecting Appropriate Management Action and Treatment

45

Heavy machinery

Heavy machinery can be used to reduce juniper 

dominance, but these treatments tend to be expensive. 

Methods include using bulldozers to push trees over, 

pulling anchor chains or steel cables with bulldozers to 

uproot trees, or use of mechanical cutting and grinding 

devices. 

Soil conditions, such as texture and moisture content, 

and machinery operation (for example, use of tight turns) 

should be evaluated, and plans should be developed to 

minimize soil surface disturbance. Impacts on desirable 

understory vegetation also may be a concern with use of 

heavy machinery, but impacts have been shown to be light 

to moderate with chaining. Chaining has not been used in 

western juniper woodlands since the 1980s.

Feller bunchers, which are currently being used, cut 

and lay groups of 3-8 trees (depending on size) on the 

ground. Bundles can be left in place, burned, or chipped. 

However, little is known about the ecological effects 

of burning piles or leaving chips on site. Soil surface 

disturbance from feller bunchers is usually minimal on 

dry soils. Depending on the price being paid for chips, 

biomass utilization can significantly offset, if not pay for, 

the cost of juniper removal.

Figure 33. Juniper thinning to 5 trees/acre (12/ha) (Ecological 

site = Deep Loamy 12-16PZ).
Selecting Appropriate Management Action and Treatment

46

Chainsaw cutting

Chainsaw cutting of juniper can be used to 

selectively remove trees with minimal soil disturbance. 

Although costs increase when treating areas with steep 

terrain or areas isolated from roads, cutting is an option in 

these areas where use of heavy machinery is not feasible. 

This may be the only treatment option in areas of cultural 

resource concern. Expense of cutting treatments increases 

when limbs or slash are spread across the site, so this 

should only be done where post-treatment erosion is a 

risk. This treatment will maintain and usually increase 

stand vigor of non-sprouting understory shrubs (that is, 

sagebrush). (a) Before chainsaw cutting. (b) One year after chainsaw cutting. All large grasses were present prior 

to cutting but <1 in. (2.5 cm) in diameter.
Selecting Appropriate Management Action and Treatment

47

(c) One year after chainsaw cutting.

(d) Three years after chainsaw cutting; herbaceous cover 25-35%.

Figure 34. Basin big sagebrush/bluebunch wheatgrassThurber’s plant association on a southwest aspect, 5,000 ft 

elevation, pre-treatment Phase III, tree canopy 25%, shrub 

cover 0.5%, herbaceous cover 2.5%, deep-rooted tall perennial 

bunchgrasses = 2/10 ft

2

.
Selecting Appropriate Management Action and Treatment

48

25. Prescribed Fire

The primary factors that will influence post-burn

response are: 

•	 Plant community composition

•	 The abundance of perennial grasses, forbs, and seed 

pools prior to treatment

•	 Ecological site (site potential)

•	 Fire severity

•	 Extent and patchiness of fire 

•	 Pre- and post-fire climate conditions 

•	 Post-treatment management. 

Prescribed fire treatments can produce desirable 

results on sites with woodlands in Phases I and II when 

there is an abundance of natives in the understory (>2 

desirable grasses/m

2

). On sites that are in late Phases II 

and III with a depleted understory, (1) fire will be difficult 

to carry through the stand as a result of limited ground 

and ladder fuels, (2) more costly inputs are likely (see 

cutting and burning), and (3) response can be difficult 

to predict. When weeds are present on the site, risk of 

failure is increased, especially if the site is warm and dry, 

or on fine-textured soils. Additional follow-up treatments 

targeted at undesirable species can be beneficial.

An initial response to fire includes decreased litter 

and woody vegetation and increased bare ground. How 

will these responses affect wildlife (that is, loss of the 

shrub layer), water runoff, and erosion in the short term? 

Mountain big sagebrush usually will recover to preburn levels within 25–35 years (varies with climate and 

seed source). Controlling fire temperature and duration 

is important for protection of the soil and understory 

vegetation.
Selecting Appropriate Management Action and Treatment

49

Figure 35. Phases I and II mountain big sagebrush/Idaho fescue 

(Ecological site = Deep North 12-18 PZ), 4,500 ft elevation, and 

north aspect (background); basin big sagebrush/basin wildrye 

(foreground) (Phase I, but little rye prior to the fire). Native 

perennial forbs doubled and Idaho fescue decreased about 1/3 in 

the first year. In year 3, perennial forbs equal to pre-burn, fescue 

about 120% of pre-burn. Foreground about a 600% increase in 

squirreltail.

Figure 36. A high-intensity wildfire was carried by the juniper 

canopy (35 to 40% cover) under extreme weather conditions, 

killing most of the understory, which included Idaho fescue, 

bluebunch wheatgrass, and Thurber’s needlegrass. Abundant 

understory vegetation 2 years after fire is cheatgrass and tumble 

mustard. If burned under cooler conditions, the native understory 

would likely have survived and dominated post-fire succession 

(Ecological site = Juniper South 12-16 PZ).
Selecting Appropriate Management Action and Treatment

50

Figure 37. Prescribed fall burns in mountain big sagebrush and 

Idaho fescue in (a) Phase II, 8-12 native grasses/m

2

, and (b) 

Phase III, 4-7 plants/m

2

. Mortality decreased perennial grasses 

to less than 2 plants/m

2

 following fire in Phase III. Phase II is 

coming back to native grasses, while Phase III has a dominant 

cover of introduced annuals. Photographs by John Bates. (a) (b)
Selecting Appropriate Management Action and Treatment

51

Burning in aspen for juniper removal

Due to high fuel-moisture conditions often found 

in aspen forests, prescribed fire can be difficult to 

implement. However, if suitable conditions exist for fire, 

burning can produce desirable results. Protection from 

livestock and wildlife use may be necessary for aspen 

establishment after treatment. Research indicates this 

could take about 3–5 years, but depends on site conditions 

and climate.

Figure 38. Aspen stand with dense sapling size (most of which 

are 40–60 years old) and western juniper in the understory. Trees 

will begin to dominate the stand in 20–30 years (Ecological site = 

Aspen Grove).

Figure 39. Aspen regeneration following a prescribed fire to 

remove juniper.
Selecting Appropriate Management Action and Treatment

52

26. Cut and Burn Combinations

The combination of cutting and burning are used 

to (1) increase ground fuels to carry fire, and/or (2) 

remove juniper slash created by cutting. This treatment 

combination is most often used in late Phase II and Phase 

III. Fall burning in Phase III can have severe effects 

on understory vegetation resulting in >75% mortality. 

Winter burning (Nov.–Mar.) has less severe effects 

resulting in 20-50% mortality of perennial grasses. Cut 

and burn treatment of Phase III stands is higher risk 

and more expensive than in Phases I and II. Cutting no 

more juniper than is necessary is recommended to keep 

the treatment as cost-effective as possible and to avoid 

building a fuel load that will result in a fire that is too 

hot. Other precautions noted earlier regarding understory 

vegetation, erosion, wildlife habitat, economic feasibility, 

and social acceptability on Phase III woodlands need to be 

considered.

Research on social acceptability of vegetation 

management in rangelands has found that citizens 

generally prefer prescribed fire as a treatment because 

it is perceived as more “natural” than other treatments. 

However, this is true only insofar as smoke levels and 

risks of adjacent property damage are low; in locations 

near human habitation, mechanical treatment may be 

more acceptable to the public. All other things being 

equal, citizens are likely to prefer chainsaw cutting over 

the use of bulldozers. No research has examined the 

relative acceptability of cutting and grinding machines.

4

4

Brunson, M.W., and B.A. Shindler, 2004, Geographic variation in 

social acceptability of wildland fuels management in the western U.S. 

Society and Natural Resources 17:661-678.
Selecting Appropriate Management Action and Treatment

53

27. Chemical Treatments

Because past chemical application on western 

juniper has met with poor or mixed results, only limited 

information is available to guide managers in using this 

method. The most important consideration for chemical 

treatment of juniper woodlands is site selection. Chemical 

treatment should only be used on sites where the herbicide 

will work as intended (for example, where the soil type 

will not interfere with the chemical’s performance) 

and the understory has potential to respond. Following 

herbicide treatment, standing dead trees may interfere 

with subsequent weed control and seeding of perennials. 

Social acceptability tends to be lower for chemical 

treatments than for any other restoration method.

Tebuthiuron

Aerial application of tebuthiuron is not 

recommended as a method for reducing western juniper 

dominance. Research has shown this method is not 

successful in killing western juniper, but can significantly 

reduce desirable understory plants. Applying tebuthiuron 

to individual trees may be an option.

Picloram

Applying picloram to individual trees around the 

canopy driplines can be highly effective. 

Other Chemicals

Velpar L, Pronone Power Pellets, Chopper and 

Arsenal treatments have been shown to be effective for 

western juniper trees up to 6 ft in height in northern 

California. Chopper and Arsenal also have shown to be 

effective for treating cut juniper stumps with green limbs 

remaining below the cut.
Selecting Appropriate Management Action and Treatment

54

28. Seeding

Success of seeding on sites where a treatment 

has been used to reduce juniper dominance is greatly 

influenced by precipitation and soil texture. When 

broadcast seeding, safe sites for seedling establishment 

should be created if possible. Roller punching to scarify 

soils, followed by broadcast seeding and scattering of 

slash, has been successful. Scattering slash is an expensive 

strategy that may only be justifiable on highly erodible 

soils and slopes.

Figure 40. Moderate-severity fire (notice needles on trees) 

where 80% of the native species in the understory survived; no 

seeding is required (Ecological site = Deep North 12-18PZ).

Figure 41. High-severity fire (notice no needles or bark remain 

on trees) where mortality of native herbaceous species was 

>80% ; 5 years after fire this site is dominated by introduced 

annual and biannual weeds; seeding required (Ecological site = 

Deep North 12-18PZ).
Selecting Appropriate Management Action and Treatment

55

Post-Treatment Management

29. How will post-treatment management affect site 

conditions?

Maintenance of desirable site conditions is most 

likely when post-treatment management remains adaptive 

and flexible, and when plans are continually reassessed. 

An optimal management approach usually considers 

short- and long-term successional responses and includes 

evaluation of the benefits of follow-up treatments. At 

minimum, a good monitoring plan might include regularly 

taking photographs at established points and keeping a list 

of dominant species throughout the project area. Active 

monitoring can be particularly informative in areas with 

negative hydrologic responses or invasive species.

How will treatment influence the distribution of 

livestock and wildlife use of the site? Rest from grazing 

following treatment will significantly improve the chances 

of success, especially if the understory is depleted. If it 

is not possible to keep animals out of the treated area, 

grazing impacts can be reduced by controlling placement 

of water and mineral supplements or grazing during 

herbaceous dormancy in the summer and fall. After fire, 

2 years of grazing rest is common practice, but plant 

response is often a better indicator of the actual amount of 

rest needed. Grazing during the growing season in the first 

and second years following treatment has been shown to 

increase mortality and decrease leaf and seed production 

of desirable grasses. Grazing after seed set in the first 2 

years following treatment has been shown to have little 

effect on plant health. 

It is important to provide opportunities to maximize 

seed production and seedling establishment. Production of 

grass seed is not likely to be significant until the second 

year post-fire. Usually, cutting and chemical applications 

minimally affect understory vegetation, but use of heavy 

equipment may have greater impact.
Appendix

56

Appendix 1: Field Assessment Form

Site Name _____________________________________

Location ______________________________________

Date__________________________________________

I. Ecological Site / Plant Association

A. Diagnostic sagebrush species____________________

__________________________________________

B. Bitterbrush present? Y / N

C. Diagnostic perennial grass(es) ___________________

__________________________________________

D. Old growth on the site (table 1)? Y / N

E. Large wood found on the site? Y / N

F. Plant association or PNV _______________________

G. Ecological Site _______________________________

a. Soil Type _______________________________

H. Historic Fire Return Interval (key 2) ______________

I. Soil erosion potential High Moderate Low

J. Species of concern ____________________________

II. Current State

A. Dominant shrub ______________ recruitment. Y / N

B. Desirable shrub ______________ recruitment. Y / N

a. % dead <10% 11-25% 26-50% >50%

C. Dominant grass(es) ___________________________

a. ≥2 desirable grasses/m2? Y / N

D. Post-settlement trees present? Y / N; Phase I II III

E. Invasive species present? Y / N

F. Evidence of surface erosion (rills, sediment dams,

pedestals, etc.)? Y / N
Appendix

57

G. Current plant community _____________________

H. Perceived problem___________________________

I. Habitat suitability for target species 

Low Moderate High

a. If low or moderate, what is missing?_________

J. The site will burn With / Without pre-treatment.

K. Social concerns _____________________________

L. Current uses________________________________

III. Landscape considerations

A. Size of area to be treated ______________________

B. How will treatment affect adjacent patches?_______

C. Treatment will fragment / link adjacent patches.

IV. Management Action

Phase I and/or II (circle treatment recommendation)

A. Cut

B. Burn

C. Seeding required Y / N 

D. Other options_______________________________

Phase II and/or III (circle treatment recommendation)

A. Partial cut and broadcast burn

B. Cut drop and leave

C. Cut drop and burn

D. Cut pile and burn

E. Seeding required Y / N 

F. Other options_______________________________

Considerations:

A. Small trees may require follow-up.

B. Weed potential, shrub layer, liability, structures, 

containment.

C. Post treatment.

D. Monitoring.
Appendix

58

Species Codes

Code Scientific Name Common Name

AMAL Amelanchier alnifolia ServiceberryARAR Artemisia arbuscula Low sagebrushARTRW Artemisia tridentata ssp. womingensis Wyoming big sagebrushARTRT Artemisia tridentata ssp. tridentata Basin big sagebrushARTRV Artemisia tridentata ssp. vaseyana Mountain big sagebrushPUTR Purshia tridentata BitterbrushSYOR Symphoricarpos oreophilis SnowberryACNE Acnatherum nelsonii Colombia needlegrassACTH Acnatherum thurberiana Thurber’s needlegrassFEID Festuca idahoensis Idaho fescuePOSA Poa secunda Sandberg bluegrassPSSP Psuedorogneria spicata Bluebunch wheatgrass

Appendix 2: Species Codes
Glossary

59

Glossary of Terms

Bare ground: exposed mineral soil that is susceptible 

to raindrop splash erosion. The size, distribution, and 

connectedness of bare ground are the most important 

contributor to site stability relative to site potential.

Cover type: see potential natural vegetation.

Ecological site: a type of land with specific physical 

characteristics that differs from other types of land in 

its ability to produce distinctive kinds and amounts of 

vegetation and its response to management. Apparently 

synonymous with ecological type used by USDA 

Forest Service, and Rangeland Ecological Site (http://

esis.sc.egov.usda.gov/Welcome/pgReportLocation.

aspx?type=ESD).

Ecological function: referred to here as the actions 

or behavior of important processes such as hydrology, 

nutrient cycling, and energy capture.

Fire Return Interval (FRI) (or fire free interval or 

return fire interval): the number of years between two 

successive fires documented in a designated area (that 

is, the interval between two successive fire occurrences); 

the size of the area must be clearly specified. Variability 

in intervals is the meaningful reality of the disturbance 

regime on the site, not the mean (MFRI).

Fluted: pockets where the cambium layer folds in on 

itself forming deep grooves or bark pockets.

Fuel: all burnable material live and dead.

Functional goals: examples are watershed health, habitat 

for a defined set of species, etc., which are met by a 

desired set of conditions on the site often determined by 

vegetation composition and structure. 

Gullies: channels that have been cut into the soil by 

moving water.
Glossary

60

Ladder fuel: material on or near the ground that will 

carry fire from the ground to the crown of trees (that is, 

sagebrush, bitterbrush, dead down wood and branches).

Management unit: an area of land defined by boundaries 

where a management strategy is to be applied. The land 

area may be composed of one or more ecological sites, 

and the entire area may or may not be treated.

Mean Fire Return Interval (MFRI) (or mean fire 

free interval): arithmetic average of all fire intervals 

determined in a designated area during a designated time 

period; the size of the area and the time period must be 

specified. MFRI only provides the central tendency; 

variability in intervals is the meaningful reality of the 

disturbance regime on the site, not the mean (MFRI). 

Post-settlement trees: trees establishing after 1860.

Potential natural vegetation (PNV): the vegetation that 

will persist under the pre-settlement disturbance regimes 

and climate. PNV is an expression of environmental 

factors such as topography, soils and climate across 

an area where cover type is a classification of existing 

vegetation. The existing cover type at any particular 

location and time may reflect a vegetation community 

anywhere along its successional pathway—from seral to 

climax.

Pre-settlement: trees establishing before 1860 (see oldgrowth). 

Old-growth: a relative term that has been based on 

morphological characteristics, actual age, or general 

period of establishment (pre- and post-settlement, before 

or after 1860).

Rills: small erosional rivulets that are generally linear and 

do not necessarily follow the microtopography that flow 

patterns do.

Savanna or savannah: grassland or shrub-steppe with 

widely scattered trees (<10% canopy cover).
Glossary

61

Soil/site stability: The capacity of an area to limit 

redistribution and loss of soil resources including 

nutrients and organic matter by wind and water (Tech. 

Ref. 1734-6, 2005).

Species of concern: Species that require special 

consideration in restoration. These include species that 

may increase following treatment (that is, noxious weeds) 

or species that are declining or appear to be in need 

of concentrated conservation actions, including State 

Endangered, State Threatened, State Sensitive, or State 

Candidate speices.

Stocking: A fully stocked site is one with enough trees 

that does or will eventually fully occupy a site (that is, at 

maturity, interspecific competition limits the expansion 

or addition of new leaf canopy). Stocking density varies 

across ecological sites and with tree size.

Water flow pattern: the path that water takes as it moves 

across the soil surface during overland flow. Evidence of 

water flow patterns include redistribution of litter, soil or 

gravel, or pedestalling of vegetation or stones.

Woodland: an area of smaller statured trees usually with 

canopy cover >10%; open 10-20%, intermediate 20-40%, 

dense >40%.

Abbreviation Definition

in. inches

ft feet/foot

m meter(s)

cm centimeter(s)

mm millimeter(s)

ha hectare

% percent

yr(s). year(s)

Abbreviations
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Manuscript approved for publication, November 27, 2007

Prepared by the U.S. Geological Survey Publishing Network

Linda Rogers

Bobbie Jo Richey

For more information concerning the research in this report, contact the 

Director, Forest and Rangeland Ecosystem Science Center, 

U.S. Geological Survey, 777 NW 9th Street 

Corvallis, Oregon 97330

http://fresc.usgs.gov
Miller and others—Western Juniper Field Guide: Asking the Right Questions to Select Appropriate Management Actions— Circular 1321