A Field Guide for Rapid Assessment of Post-Wildfire 

Recovery Potential in Sagebrush and Piñon-Juniper 

Ecosystems in the Great Basin

Evaluating Resilience to Disturbance and Resistance to Invasive 

Annual Grasses and Predicting Vegetation Response

Richard F. Miller, Jeanne C. Chambers, and Mike Pellant

Rocky Mountain General Technical Report

Forest Service Research Station RMRS-GTR-338 July 2015

United States Department of Agriculture
Miller, Richard F.; Chambers, Jeanne C.; Pellant, Mike. 2015. A field guide for rapid assessment of postwildfire recovery potential in sagebrush and piñon-juniper ecosystems in the Great Basin: Evaluating 

resilience to disturbance and resistance to invasive annual grasses and predicting vegetation response.

Gen. Tech. Rep. RMRS-GTR-338. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky 

Mountain Research Station. 70 p.

Abstract

This field guide provides a framework for rapidly evaluating post-fire resilience to disturbance, or recovery 

potential, and resistance to invasive annual grasses, and for determining the need and suitability of the 

burned area for seeding. The framework identifies six primary components that largely determine resilience to 

disturbance, resistance to invasive grasses, and potential successional pathways following wildfire, as well as the 

information sources and tools needed to evaluate each component. The components are: (1) characteristics of 

the ecological site; (2) vegetation composition and structure prior to the wildfire; (3) fire severity; (4) post-wildfire 

weather; (5) post-wildfire management, especially grazing; and (6) monitoring and adaptive management. The 

tools provided are: (1) a conceptual model of the key components that largely determine resilience to disturbance 

and resistance to invasive annual grasses of the burn area, (2) a guide to evaluate post-wildfire severity, 

(3) indicators to estimate pre-wildfire plant composition and structure if not known, and (4) an evaluation score 

sheet to rate an area’s potential post-wildfire resilience to disturbance, resistance to invasive annual grasses 

and, thus, the need for seeding and probability of success.

Keywords: restoration, post-fire rehabilitation, seeding, succession, invasive annual grasses, cheatgrass

Authors 

Richard F. Miller, is a Professor Emeritus of Range and Fire Ecology, Eastern Oregon Agricultural Research 

Center, Oregon State University, Corvallis, Oregon; Jeanne C. Chambers, is a Research Ecologist, USDA 

Forest Service, Rocky Mountain Research Station, Reno, Nevada; Mike Pellant, is a Rangeland Ecologist, 

Bureau of Land Management, Boise, Idaho.
Acknowledgments

We sincerely thank all of the reviewers who commented on the manuscript and Eugénie MontBlanc for assisting 

with manuscript coordination. We acknowledge the Sagebrush Steppe Treatment Evaluation Project (http://

www.sagestep.org) for increasing our understanding of vegetation response following disturbance in these 

ecosystems. We also acknowledge the USDA-Natural Resources Conservation Service (NRCS) of Nevada and 

Oregon for the guidelines presented in Appendix 2, and Steve Campbell with the NRCS for his input in Appendix 

3. This field guide is a product of the Great Basin Fire Science Exchange, which is funded by the Joint Fire 

Science Program, and which received administrative support from the University of Nevada, Reno. Additional 

support was provided by the USDA Forest Service, Rocky Mountain Research Station and the Bureau of Land 

Management.
Contents

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

Purpose...............................................................................................................................2

Approach.............................................................................................................................2

Area of Application ............................................................................................................4

Supporting Information........................................................................................................8

Key Questions Addressing the Primary Components of 

Resilience and Resistance ................................................................................ 9

1—Ecological Site Characteristics .....................................................................................9

2—Pre-Wildfire Vegetation................................................................................................17

3—Wildfire Severity...........................................................................................................22

4—Post-Wildfire Weather..................................................................................................25

5—Post-Wildfire Grazing...................................................................................................26

6—Monitoring and Adaptive Management ........................................................................28

Post-Wildfire Vegetation Treatment Assessment ............................................. 29

State and Transition Models..............................................................................................29

Land Unit Evaluation Score Sheet ....................................................................................29

Seeding: Suitability and Need ...........................................................................................30

Selecting Areas Within the Burn for Seeding.................................................... 37

Key References.................................................................................................... 39

Literature Cited .................................................................................................... 41

Appendices

1–Primary Components and Attributes That Influence Resilience to 

Disturbance, Resistance to Invasive Annual Grasses, and Successional Trajectories.......44

2–Examples of Elevation Breaks and Plant Indicators for Soil Temperature 

Regimes in Two MLRAs......................................................................................................46

3–What is the Meaning of a Soil Family Name? ...................................................................47

4–Post-Wildfire Indicators of Fire Severity..............................................................................51

5–State and Transition Models (STMs) for Five Generalized Ecological 

Types for Big Sagebrush (from Chambers and others 2014b) ...........................................52

6–Examples of States, Phases, and Transitions Following Prescribed Fire 

Treatment for Three General Ecological Types in Different Phases and Precipitation 

Zones (PZ) ..........................................................................................................................58

7a–Score Sheet for Rating Resilience, Resistance to Annual Invasive 

Grasses, and the Need and Suitability for Seeding of an Ecological Site or Type 

Following Wildfire................................................................................................................62

7b–Explanation of Variables Used in the Resilience and Resistance 

Score Sheet ........................................................................................................................64

7c–Example of Rating Resilience and Resistance to Invasive 

Annual Grasses...................................................................................................................65

8–Definitions of Terms Used in This Field Guide ...................................................................68
USDA Forest Service RMRS-GTR-338. 2015 1

Immediately following a wildfire, rapid response teams such as the Burned 

Area Emergency Response (BAER) and Emergency Stabilization and Recovery 

(ES&R) teams must quickly evaluate large and often heterogeneous areas for 

erosion and invasive species potential. To effectively allocate resources and 

apply the most appropriate treatments, these teams must be able to rapidly 

determine the resilience to disturbance (recovery potential) and resistance 

to invasive annual grasses of the burned area. Important questions for these 

teams to address are:

1. What is the resilience (recovery potential) of the ecological sites in the 

burned area?

2. How resistant are they to invasive annual grasses?

3. How susceptible is the burned area to erosion? 

4. What areas within the burned area need seeding and are suitable for 

treatment?

These questions can be addressed by evaluating six primary components 

that largely drive plant successional pathways following wildfire. These 

components are: (1) characteristics of the ecological site; (2) composition and 

structure of vegetation present prior to the wildfire; (3) fire severity; (4) postwildfire weather; (5) post-wildfire management, especially grazing; and 

(6) monitoring and adaptive management. Components (1) and (2) are the 

primary drivers of potential resilience, resistance to invasive annual grasses, 

and plant successional pathways for the various ecological sites present on 

the burned area. However, components (3) through (6) can modify the potential resilience and resistance following wildfire and thus plant succession.

Resilient ecosystems have the capacity to regain their fundamental structure, 

processes, and function following disturbance, stressors, and management 

treatments. The resilience of an ecosystem reflects its recovery potential and 

is determined by environmental characteristics and ecological conditions such 

as current vegetation at the time of the disturbance. Resistant ecosystems 

have the ability to retain their fundamental structure, processes, and function (or remain largely unchanged) despite disturbance and stressors. The 

resistance of an ecosystem to invasive annual grasses is a function of the 

Introduction

USDA Forest Service RMRS-GTR-338. 2015 1
2 USDA Forest Service RMRS-GTR-338. 2015

environmental and ecological characteristics of an ecosystem that limit the 

population growth and expansion of the invasive species. Ecosystems that are 

both resilient and resistant provide valuable ecosystem services such as clean 

air, water, forage, and wildlife habitat.

Purpose

The purpose of this field guide is to help managers effectively meet the 

management objectives of increasing or restoring resilience to disturbances 

and resistance to invasive annual grasses following wildfire in sagebrush 

and piñon and/or juniper ecosystems. This field guide provides a framework 

that will enhance the ability of rapid response teams to: (1) quickly evaluate 

post-wildfire resilience, resistance to invasive annual grasses, and potential 

successional pathways immediately following wildfire; and (2) assess the 

need and suitability of the area for seeding. This field guide can also be used 

as a training tool to increase the observational skills needed for assessing 

resilience to disturbance and resistance to invasive annual grasses for areas of 

concern across various ecological sites.

Approach

This field guide presents a framework for conceptualizing and synthesizing 

information gathered from observation, experience, ecological site descriptions, soils surveys, and other sources for the rapid evaluation of post-wildfire 

resilience and resistance to invasive annual grasses. A set of Key Questions 

related to the six primary components shown in fig. 1 are used to evaluate 

resilience, resistance to invasive annual grasses, and potential successional 

pathways, and to determine the need and suitability of areas within the burn 

for seeding. The guide also provides the following set of tools: (1) characteristics of the six primary components that influence resilience and resistance 

to invasive annual grasses, (2) ecological site indicators that help identify 

an area’s resilience and resistance to invasive annual grasses, (3) criteria for 

evaluating post-wildfire severity, (4) state-and-transition models for five 

generalized ecological types of big sagebrush that describe potential successional pathways, and (5) an evaluation score sheet. The evaluation score sheet

(Appendix 7) helps managers quickly rate potential post-wildfire resilience 

and resistance to invasive annual grasses and the need and suitability for 

seeding across a burned area. The quality of the rapid assessment depends 

on: (1) the assessment team’s local expertise of soils, plants, and ecology; (2) 

familiarity with the burned area; and (3) amount of available information on 

the burned area.
USDA Forest Service RMRS-GTR-338. 2015 3

Figure 1. A simple conceptual model of the primary components that drive plant successional trajectories 

following wildfire. These components are the basis for a series of key questions to be addressed when 

evaluating resilience to fire and resistance to invasive annual grasses as well as predicting post-wildfire and 

seeding responses for an area of concern. 
4 USDA Forest Service RMRS-GTR-338. 2015

Area of Application

This field guide was developed for the northern Great Basin and Columbia 

River Plateau (fig. 2), which encompasses 11 Major Land Resource Areas 

(MLRAs) (table 1). MLRAs are geographically associated land resource units, 

usually encompassing millions of acres.They are characterized by particular 

patterns of soils, geology, climate, water resources, and land use. The MLRA 

in which the wildfire occurs provides important information for site evaluation, including: 

1. The elevation, topographic position, and indicator species used to identify 

soil temperature/moisture regimes that are closely linked to resilience to 

disturbance and management treatments as well as resistance to invasive 

annual grasses (fig. 3, Appendixes 1 and 2).

2. The relevant ecological site descriptions (ESDs; see definitions in 

Appendix 8). ESDs are usually unique to each MLRA, but similar ESDs can 

occur across different MLRAs. 

3. The potential vegetation (described in the ESD). Species composition 

may change across MRLAs, but the functional roles of plant groups (for 

example, deep-rooted and shallow-rooted perennial grasses, perennial 

forbs, and shrubs) are usually similar across MLRAs within the Great Basin 

and Columbia River Plateau regions.

When extrapolating plant response across different wildfires within the 

region, comparing similarities among specific ecological site characteristics

(including soil temperature/moisture regimes and pre-fire composition of the 

plant groups, such as deep-rooted perennial grasses) is usually more important than differences in geographic locations within or across MLRAs.
USDA Forest Service RMRS-GTR-338. 2015 5

Figure 2. Major Land Resource Areas (MLRAs) located in the Great Basin and Columbia River 

Plateau Region: Columbia Plateau (8); Blue Mountain Foothills (10); Snake River Plain (11); 

Klamath Valleys (21); Malheur High Plateau (23); Humboldt Area (24); Owyhee High Plateau 

(25); Carson Basin and Mountains (26); Fallon-Lovelock (27); Great Salt Lake (28A); and Central 

Nevada Basin and Range (28B) (derived from USDA Natural Resources Conservation Service 

[2011] by Eugénie MontBlanc, University of Nevada, Reno).
6 USDA Forest Service RMRS-GTR-338. 2015 Table 1. Major Land Resource Area (MLRA) names and identification numbers (see map in fig. 2) included in this field guide. For each MLRA, the size of land area, the states listed in descending order of proportion of area covered, most common elevation range (extreme), geology, common soil orders, range of average annual precipitation (extremes), and range in temperatures are described. The field guide only covers the sagebrush, salt-desert, and piñon pine and juniper ecological types within these MLRAs. MLRAs 8, 10, and 11 are located in the Northwestern Wheat and Range Region. The remaining MLRAs are located in the Western Range and Irrigated Region. Descriptions are derived from USDA Natural Resources Conservation Service (2011). MLRA (id #) Area (mi2) States Elevation (ft) Geology Soils Precipitation (in) Temp (°F) Columbia Plateau (8) 18,505 WA OR ID 1,300–3,600 basalt Mollisols 10–16 (6–36) 48-54 Blue Mt Foothills (10) 17,515 OR ID 1,300–6,600 basalt alluvium sedimentary Mollisols Aridisols 8–16 (41) 36–53 Snake River Plain (11) 16,475 ID OR 2,100–5,000 Idaho Batholith, basalts Aridisols 7–12 (20) 41–55 Klamath Valleys (21) 11,495 CA OR 2,600–4,600 (>7,000) basalt rhyolite andesite Mollisols 12–30 (9-58) 39–52 Malheur High Plateau (23) 22,896 OR NV CA 3,900–6,900 (>9,000) basalt & andesite Aridisols Mollisols 6–12 (>50) 39–52 Humboldt Area (24) 12,680 NV OR 3,950–5,900 (>8,850) alluvium (some andesite & basalt) Entisols Inceptisols Mollisols 6–12 (40) 38–53 Owyhee High Plateau (25) 28,930 NV ID OR UT 3,000–7,550 (>9,800) andesite basalt rhyolite Aridisols Mollisols 7–16 (>50) 35–53 Carson Basin & Mts (26) 6,520 NV CA 3,900–6,550 (13,100) granitic andesite basalt Aridisols Mollisols 5–36 37–54 Fallon-Lovelock (27) 12,565 NV CA 3,300–5,900 (<7,800) alluvium andesite basalt Aridisols Entisols 5–10 (19) 43–54 Central NV Basin & Range (28B) 23,555 NV 3,950–6,560 basin 6,560–11,150 mts playa lakebed deposits, old- sedimentary Aridisols Entisols Mollisols 5–12 (49) 39–53 Great Salt Lake (28A) 36,775 UT NV ID 4,900–6,550 basin 6,550–11,900 mts carbonate (north) andesite basalt (south) alluvium & lakebed deposits Aridisols Entisols Mollisols 4–12 (basins) 8–36 (mountains) 34–52
USDA Forest Service RMRS-GTR-338. 2015 7

Figure 3. A conceptual model that illustrates the factors influencing resilience to treatment and resistance to 

invasive annual grasses. Ecological site characteristics or environmental factors are the primary factors that 

influence soil temperature/moisture regimes and potential vegetation. The regimes are identified in soil maps 

as mesic (warm), frigid (cool), cryic (cold), aridic (dry), and xeric (moist). Potential vegetation + disturbance 

history + time since disturbance or treatment = current vegetation. If all of the ecological site characteristics 

are favorable and the site attributes and processes are all functioning within the natural range of variability, 

then levels of resilience to wildfire and resistance to invasive species are near potential for that site. However, 

if the site is not at potential because one or more components are below potential or missing (for example, 

perennial grasses are severely depleted or invasive annual grasses are abundant), resilience to wildfire and/or 

resistance to invasive annual grasses will be lower than potential (adapted from Chambers and others 2014a).
8 USDA Forest Service RMRS-GTR-338. 2015

Supporting Information

The framework for the field guide is based on a recent synthesis of the stateof-our knowledge titled, “A Review of Fire Effects on Vegetation and Soils 

in the Great Basin Region: Response and Ecological Site Characteristics,” 

RMRS-GTR-308, by Miller and others (2013). Additional information required 

for evaluating post-wildfire areas includes soil surveys, ecological site descriptions, and potential and current vegetation (see http://websoilsurvey.sc.egov.

usda.gov/App/HomePage.htm; http://www.nrcs.usda.gov/wps/portal/nrcs/

main/national/technical/ecoscience/desc/).

This is not a field guide for restoration/rehabilitation methods following 

wildfire, but rather a guide to evaluate the need for restoration and seeding 

based on vegetation composition and structure present prior to the wildfire, 

resilience and resistance to invasive annual grasses, and suitability of the 

post-wildfire area for seeding based on ecological site characteristics. Once 

the suitability of a site and need for seeding have been determined, restoration/rehabilitation methods can be found in references such as Field Guide for 

Restoration of Sagebrush-Steppe: Ecosystems with Special Emphasis on Greater 

Sage-Grouse Habitats, by Pyke and others (in preparation), Restoring Western 

Ranges and Wildlands, by Monsen and others (2004), and the Great Basin Fire 

Science Exchange website references on post-fire management (http://www.

gbfiresci.org).
USDA Forest Service RMRS-GTR-338. 2015 9

In ecology, the term mesic

is often used to mean moist 

or medium water supply for 

plant growth. However, in soil 

terminology and soil family names, 

mesic refers to warm soils, which in 

the Great Basin are often occupied 

by Wyoming big sagebrush and 

have relatively low resistance 

to invasive annual grasses (see 

Appendix 3, fig. 4).

USDA Forest Service RMRS-GTR-338. 2015 9

Key Questions 

Addressing the Primary 

Components of Resilience 

and Resistance

Post-wildfire ecological function and plant successional pathways are closely 

related to and dependent on: (1) ecological site characteristics, (2) current vegetation (composition and structure) present prior to the wildfire, 

(3) wildfire severity, (4) post-wildfire weather, (5) post-wildfire grazing, and 

(6) monitoring and adaptive management.

The key questions identify specific characteristics of the six primary components that drive plant succession following wildfire and influence longer-term 

outcomes (fig. 1).

1—Ecological Site Characteristics 

Climate, topography, and soils affect water availability, temperature regimes, 

potential vegetation, and productivity (fig. 3, Appendix 1). These, in turn, affect resilience to disturbance, resistance to invasive annual grasses, the need 

for vegetation treatments, and potential success of restoration treatments. 

Owing to underlying differences in 

characteristics of ecological sites, resilience after disturbance and resistance 

to invasive annual grasses following 

wildfire differ. Five ecological types for 

big sagebrush in the Great Basin and 

Columbia River Plateau regions are 

presented in table 2. They represent 

groupings of ecological sites that are 

occupied by Wyoming or mountain big 

sagebrush, span a range of soil temperature/moisture regimes (warm/dry to 
10 USDA Forest Service RMRS-GTR-338. 2015

Table 2. The five generalized ecological types for big sagebrush, their characteristics, and their resilience to wildfire and resistance to invasive annual grasses. 

Ecological type Site characteristics Resilience and resistanceWarm and dryWyoming big sagebrush

Soil temperature/moisture regime: Mesic/aridic Precipitation: 8–12 inchesIndicator shrubs: Artemisia tridentata ssp. wyomingensisIndicator grasses: Pseudoroegneria spicata, Achnatherum thurberianum on cooler/moister sites; A. hymenoides, A. comata, Elymus elymoides, Poa secunda on drier/warmer sites

Resilience – Low. Effective precipitation limits site productivity. Decreases in site productivity, herbaceous perennial species, and ecological conditions further decrease resilience.Resistance – Low. High climate suitability to cheatgrass and other invasive annual grasses. Resistance generally decreases as soil temperature increases, but establishment and growth are highly dependent on precipitation and vary among years.

Warm and moistBig sagebrushPiñon and juniper potential

Soil temperature/moisture regime: Cool mesic to warm frigid/xeric Precipitation:12–14 inchesIndicator shrubs: A. tridentata ssp. wyomingensis, A. tridentatassp. vaseyana, Purshia tridentataIndicator grasses: Pseudoroegneria spicata

Resilience – Moderate. Precipitation and productivity are moderately high. Decreases in site productivity, herbaceous perennial species, and ecological conditions can decrease resilience.Resistance – Moderately low. Climate suitability to invasive annual grasses is moderately low but increases as soil temperatures increase.

Cool and moistMountain big sagebrush

Soil temperature/moisture regime: Cool mesic to cool frigid/xericPrecipitation: 12–14 inchesIndicator shrubs: Artemisia tridentata ssp. vaseyana, Purshia tridentataIndicator grasses: Festuca idahoensis, Poa fendleriana

Resilience – Moderate. Precipitation and productivity are moderately high. Decreases in site productivity, herbaceous perennial species, and ecological conditions can decrease resilience.Resistance – Moderate. Climate suitability to invasive annual grasses is moderate but increases as soil temperatures increase. 

Cool/cold and moistMountain big sagebrush Piñon and juniper potential

Soil temperature/moisture regime: Cool frigid/xericPrecipitation: 12–14+ inchesIndicator shrubs: A. tridentata ssp. vaseyana, Amelanchierssp., Symphoricarpos ssp.Indicator grasses: Festuca idahoensis, Koeleria macrantha, Melica bulbosa

Resilience – Moderately high. Precipitation and productivity are generally high. Decreases in site productivity, herbaceous perennial species, and ecological conditions can decrease resilience.Resistance – Moderately high. Low climate suitability to invasive annual grasses. 

Cold and moistMountain big sagebrush

Soil temperature/moisture regime: Cryic/xericPrecipitation: 14+ inchesIndicator shrubs: A. tridentata ssp. vaseyana, Amelanchierssp., Symphoricarpos ssp.Indicator grasses: Festuca idahoensis, Koeleria macrantha, Melica bulbosa

Resilience – Moderately high. Precipitation and productivity are generally high. Short growing seasons can decrease resilience on coldest sites.Resistance – High. Low climate suitability to invasive annual grasses. 
USDA Forest Service RMRS-GTR-338. 2015 11

cold/moist), and characterize a large portion of the Great Basin and Columbia 

River Plateau regions. These can be useful when site-specific ESDs are not 

available or it is desirable or necessary to group ecological sites across a burn 

area. To determine the relative resilience and resistance of specific or generalized ecological sites(s) in the post-wildfire area, it is necessary to evaluate 

the soil temperature/moisture regimes, potential vegetation, and vegetation 

present and condition prior to the wildfire. If pre-wildfire vegetation composition, structure, and condition are unknown, assessment teams can make a 

best estimate based on a set of indicators listed in 2—Current Vegetation.

Soil Temperature Regime

1. Are the soils warm (mesic), cool (frigid), or cold (cryic) (fig. 4A and B)?

a. This information can be attained from soil surveys, soil family names, 

and/or elevation based on criteria used in soils surveys in the appropriate MLRA (appendices 2 and 3). Potential vegetation for the ecological 

sites of concern can also be indicators of soil temperature regime (see 

“Potential Vegetation” in next section).

2. Do elevation and aspect place the ecological site on the upper or lower end 

of the soil temperature regime (for example, warm-mesic versus coolmesic) (fig. 4)? 

a. In reality, soil temperature/moisture regimes are gradients. Thus, it 

helps to know if the ecological site is warm (lower one-half), or cool 

(upper one-half) relative to a specific soil temperature regime (fig. 4, 

Appendix 2). This can usually be determined by the elevation and aspect 

of the ecological site, which is adjusted for each MLRA. Indicator plant 

species can also be helpful. North and south aspects with >15 percent 

slope are usually adjusted by 500 ft. For example, in MLRA 23, the 

elevation boundary for mesic and frigid soils is 4,000 ft, but it is adjusted 

down to 3,500 ft on north aspects and up to 4,500 ft on south aspects.
12 USDA Forest Service RMRS-GTR-338. 2015

Figure 4. A conceptual model of 

(A) resilience to disturbance and 

(B) resistance to invasive annual 

grasses for Wyoming big sage 

(ARTRw), mountain big sagebrush 

(ARTRv), and mountain big 

sagebrush-snowberry (ARTRvSYOR) along an elevation/

productivity gradient in which soil 

temperature/moisture regimes grade 

from warm/dry (mesic/aridic) to cold/

moist (cryic/xeric). Soil moisture 

availability along these gradients is 

modified by soil characteristics. The 

mountain big sagebrush-snowberry 

(ARTRv-SYOR) type is similar to 

mountain shrub in Nevada and Utah 

and often includes mountain big 

sagebrush, snowberry, serviceberry, 

bitterbrush, and curl-leaf mountain 

mahogany. Resilience and resistance 

are affected by topography; the 

dashed dark blue and red lines 

in the resilience graph illustrate 

the effects of aspect. Ecological 

site characteristics determine the 

potential resilience and resistance. 

However, potential resilience and 

resistance can be lowered if certain 

components such as perennial grass 

abundance are depleted as a result 

of disturbance history or extreme 

climate conditions. In the resistance 

graph, the solid green line represents potential resistance to annual invasives in the reference state, and the 

red line indicates decline in resistance as a result of being in the at-risk-phase. The relationship between soil 

temperature/moisture regimes and elevation changes across MLRAs (see Appendix 2). Soil temperature/

moisture regimes are not separated by distinct boundaries but represent a gradient (shown by the overlapping 

arrows). Changes in soil temperature and moisture can be gradual (a gradual increase in elevation) or 

abrupt (a shift from a south to an opposing north aspect). The shift from one sagebrush subspecies to 

another does not have a definite lower or upper elevation limit but will vary with other site attributes, including 

location (MLRA), soils, aspect, and microtopography. For example, an overlap of cool (frigid) mountain big 

sage (ARTRv) into warm (mesic) Wyoming big sagebrush (ARTRw) can occur and is often influenced by 

soil moisture availability. As environmental gradients move to the right, resilience and resistance increase. 

Productivity and, thus, fuel loads also increase, resulting in a greater potential for more frequent fires (from 

Chambers and others 2014a).
USDA Forest Service RMRS-GTR-338. 2015 13

Soil Moisture Regime 

1. Does the ecological site have a dry-aridic (<10 inches precipitation [ppt]), 

aridic (10 to 12 inches ppt), or xeric (>12 inches ppt) moisture regime (see 

table 3 and figs. 5 and 6 for indicator species)?

a. This information can also be attained from soil surveys, soil family 

names, and/or elevation (based on criteria used in soils surveys in the 

appropriate MLRA) (appendices 2 and 3).

2. Is the soil depth very shallow (<10 

inches), shallow (10 to 20 inches), 

moderately deep (20 to 36 inches), 

or deep (>36 inches)?

a. Soil depth influences the water 

storage capacity of the ecological 

site. For example, a very shallow 

soil (<10 inches) in a xeric (>12 

inches) precipitation regime may 

be mapped as aridic due to limited water storage capacity. 

b. A general estimate of soil depth can be determined by the species or 

subspecies of sagebrush that should occupy the area and their height 

(fig. 5 and table 3). However, digging small soil pits is the best technique 

to determine soil depth.

c. Big sagebrush (Artemisia tridentata) are typically found on moderately 

deep to deep soils >20 inches depth.

3. Is the soil texture clay, sand, silt, loam, clay-loam, sandy-loam, or silt-loam 

(Appendix 3)?

a. Texture is an important soil characteristic because it influences soil 

water capture and storage. Soils with loamy textures typically have the 

greatest capacity to both capture and store water for plant use.

What is in a soil family name?

A soil family name includes important information on related soil characteristics that influence ecological site resilience to disturbance, resistance to 

invasive annual grasses, and potential vegetation. This includes information 

related to relative organic matter content (Aridisols or Mollisols), soil depth 

(for example, mention of a restrictive layer), texture, and soil temperature/

moisture regime (mesic, frigid, or cryic/aridic, or xeric) (see Appendix 3 for 

examples).

In ecology, the term xeric is 

often used to mean environments 

with little moisture. However, in 

soil terminology and soil family 

names, xeric refers to moist soils (as 

compared to dry or wet), which in 

the Great Basin are areas receiving 

typically >12 inch ppt (see Appendix 

3, fig. 4).
14 USDA Forest Service RMRS-GTR-338. 2015

Table 3. Ecological site characteristics that commonly occur with different sagebrush and associated shrub 

species, although outliers occur. Lower elevation limits vary widely across Major Land Resource Areas. For 

example, the elevation where the transition of Wyoming to mountain big sagebrush occurs (modified by 

aspect) is commonly around 4,500 ft in the High Malheur Plateau (MLRA 23) and 6,500 to 7,500 ft in the 

Central Nevada Basin and Range (MLRA 28B) (from USDA-NRCS Plant Guide; Mahalovich and McArthur 

2004). 

Soil

Species PPT 

(in) Elevation (ft) Depth (in)

Moisture 

regime

Temperature 

regime

Texture and other 

characteristics

Wyoming big 

sagebrush 8–12 2,600–7,200 10-30 aridic mesic loamy soils with high clay content

Basin big 

sagebrush 8–16 600–2,100 >36 aridic-xeric mesic loamy to sandy

Mountain big 

sagebrush >12 2,600–10,000 18-36 xeric frigid-cryic loamy to gravely to clay loam

Xeric big 

sagebrush 12–16 2,600–4,900

(7,200)

>16 xeric mesic basalt or granitic

Low sagebrush 2,300–12,000 <20 aridic-xeric frigid-cryic rocky, shallow, clay 

soils

Black sagebrush <12 2,000–10,000 <20 aridic mesic-frigid shallow, stony, 

calcareous

Snowbank big 

sagebrush >12 6,800–10,000 >20 xeric cryic snow accumulation areas

Other Shrubs

Snowberry >14 4,800–10,000 >20 xeric cool-frigid 

to cryic sandy to clay loams

Serviceberry >14 5,000–8,500 >20 xeric cool-frigid 

to cryic loam

Shadscale 4–8 4,000–7,000 >20 dry-aridic mesic-frigid Aridisols (uplands)

Spiny hopsage <8 2,000–5,500 >20 dry-aridic mesic Aridisols

Mormon tea <10 3,000–7,500 >20 dry-aridic mesic sandy, gravely, rocky 

Aridisols
USDA Forest Service RMRS-GTR-338. 2015 15 SOIL TEMPERATURE GRADIENT Cold Cool Warm

DRY MOIST

SOIL MOISTURE GRADIENT

LARGE

SAGEBRUSHES 

OF COLD to 

WARM SITES

DWARF

SAGEBRUSHES

OF COLD-COOL

SITES

Cold-Cool

A. cana

Poor 

drainage

A. arbuscula

spp

thermopola

Shallow

claypan

Non-calcic

A. longiloba

Shallow

claypan

A. tripartita

spp

rupicola

Shallow or

deep

Lithic

DWARF

SAGEBRUSHES

OF WARMER

SITES

A. nova

Gravelly

Warm

Calcic

A. tripartita

spp

tripartita

Deep

Stony

A. rigida

Shallow 

Stony

A. arbuscula

spp

arbuscula

Shallow

hardpan

Gravelly

Calcic

A. pygmaea

Gravelly

Calcic

A. tridentata

spp

xericensis

bonnevillensis

Moderately

deep

A. tridentata

spp

wyomingensis

Moderately

deep

A. 

tridentata

spp

tridentata

Deep

A. 

tridentata

spp

vaseyana

Moderately

deep

A.spiciformis

Deep

A. rothrockii

Moderately

deep

Figure 5. Major sagebrush taxa in the Great Basin and Columbia River Plateau positioned along gradients 

of soil temperature and soil moisture (adapted from Robertson and others 1966; McArthur 1983; West 1983; 

West and Young 2000; Rosentreter 2005; Schultz 2009, 2012). Key soil characteristics associated with each 

species are shown under the species name. Relative abundance of the sagebrush species and subspecies is 

color coded: grey = scarce, orange = common, and green = dominant. 
16 USDA Forest Service RMRS-GTR-338. 2015

Potential Vegetation

The potential vegetation of an ecological site, as described in an ESD, is a function of ecological site characteristics (climate, topography, and soils), attributes 

and processes (soil temperature/moisture regime, soil processes, and vegetation dynamics), and natural disturbance regimes (see fig. 3 and the reference 

state in ESD state and transition models (STMs) in Appendix 5). Most ESDs 

contain a detailed species list by life-form and the relative proportion of these 

species expected in the reference state (reference community phase). In the 

Great Basin and Columbia River Plateau regions, strong topographic gradients 

influence temperature and moisture, and are often reflected by changes in the 

dominant plant species and subspecies, such as sagebrush, which can be good 

indicators of soil temperature/moisture regimes (table 3). 

1. What were the dominant shrub species or subspecies of sagebrush (fig. 5, 

table 3; see Shultz 2012)?

a. Wyoming big sagebrush is most commonly found on moderately deep, 

mesic/aridic (warm/dry) soils but can occur on warm-frigid/aridic (cool/

dry) soils (figs. 4 and 5). 

b. Mountain big sagebrush is most commonly found on moderately deep, 

frigid and cryic soils with xeric moisture regimes (cool/moist) (figs. 4 

and 5).

c. In zone where the big sagebrush subspecies come together, often near 

the threshold of mesic and frigid and/or aridic and xeric soil regimes, identification of subspecies can be difficult as a result of hybridization. Some 

Figure 6. The general distribution of common, deep-rooted grasses and cheatgrass across a soil temperature/

moisture gradient in the Great Basin and Columbia River Plateau.
USDA Forest Service RMRS-GTR-338. 2015 17

of these hybrid crosses have been separated out including Bonneville big 

sagebrush in Utah and xeric big sagebrush in Idaho, but in other areas 

they have not.

2. Some shrub species associated with sagebrush (usually present or codominant but not dominant) are also indictors of soil temperature/moisture 

regimes. For example, snowberry and serviceberry are common on coolfrigid and cryic (cool-cool and cold) soils with >14 inches ppt. In upland 

non-saline soils, shadscale and spiny hopsage often occur on mesic/dryaridic (warm/dry) soils typically with <8 inches ppt (table 3).

3. What are the dominant perennial grass species on the ecological site?

a. The perennial grass species that are potentially common or dominant in 

the reference state as described in the ESD (see Appendix 5 for examples 

and Appendix 8 for definition) for the ecological site are general indictors 

of moisture availability, temperature (fig. 6), and soil depth and texture.

b. If Sandberg’s bluegrass is the dominant grass, it can be an indicator of 

very shallow soils (< 10 inches) or, if on shallow to moderately deep soils 

(>10 inches), it can indicate improper grazing resulting in the loss of larger 

bunchgrasses. A high abundance of bottlebrush squirreltail is often an 

indicator of high severity and/or frequent disturbance. These two species 

increase resistance to invasive annual grasses on areas with shallow soils 

or where perennial native herbaceous species have been depleted.

2—Pre-Wildfire Vegetation

The composition and abundance of perennial vegetation that persists following 

wildfire is one of the primary drivers of 

both short- and long-term successional 

pathways. Post-wildfire vegetation is 

a function of pre-wildfire vegetation 

composition and structure, fire severity, 

post-wildfire herbivory, and weather.

Pre-Wildfire Composition 

and Structure Known

1. What was the composition and structure (cover and/or density) of perennial native grasses and forbs, and invasive annual grasses just prior to the 

wildfire?

a. Were the native perennials absent or severely depleted? In the severely 

depleted phase, perennial grasses were <2/m2 (10 ft2) for xeric and <3/

m2 (10 ft2) for aridic sites; invasive annual grasses were dominant (in 

Year-to-Year Invasive Annual 

Grass Variation

During a 20-year period on a mesic/

aridic ecological site in Utah, annual 

grass cover varied from trace in dry 

years to 25 percent in wet years.
18 USDA Forest Service RMRS-GTR-338. 2015

years with adequate winter/

spring moisture), and/or woody 

species (shrubs or trees) were 

near maximum cover.

b. Were they co-dominant with invasive annual grasses? The area is 

at risk if perennial grass densities 

were <2/m2 (10 ft2) for xeric and <3/m2 (10 ft2) for aridic, and/or cover 

typically did not exceed 10 percent prior to the fire.

c. Were perennial deep-rooted grasses and forbs dominant? If the area is 

not at risk, perennial deep-rooted grasses and forbs should be about >15 

to 25 percent cover or greater, and invasive annual grasses should be <5 

percent cover in years with adequate spring moisture.

d. What was the shrub canopy cover? Areas with >15 percent shrub 

canopy cover often burn hotter than areas with less cover or more open 

Perennial Grass Densities

A higher abundance of perennial 

grasses are required for recovery 

on sites with mesic/aridic regimes 

owing to low resilience and 

resistance.

Figure 7. Moderate to high severity fire (A) resulting in nearly 100% consumption of surface litter and seed. 

Low severity fire resulting in (B) residual litter and cheatgrass seed, and (C) intact medusahead litter.

C

A

B
USDA Forest Service RMRS-GTR-338. 2015 19

Figure 8. The relationships among pre-fire perennial herbaceous vegetation, wildfire severity and the post-fire 

cheatgrass seed bank, and seeding decisions. The red and green blocks represent two situations where a 

“don’t seed’ decision may be appropriate. The green blocks represent burned areas where sufficient perennial 

plants were present prior to the fire, fire severity was low to moderate, and pre-fire cheatgrass seed density 

was low or seeds were mostly consumed in the fire. In contrast, the red blocks represent areas where native 

perennials were severely depleted, cheatgrass was common to abundant, and cheatgrass seed mortality 

was limited as a result of low to moderate fire severity (sagebrush cover was less than 15%). The blue blocks 

represent areas where post-fire cheatgrass seed density is low as a result of high fire severity, and a 1-year 

window for seeding with minimal competition from cheatgrass typically occurs. The yellow blocks represent 

a less predictable vegetation response in the decision process that will require use of the score sheet to 

evaluate the areas resilience and resistance to annual invasives, information on past seeding results, and local 

experience.

canopies. Hotter fires typically consume the majority of invasive annual grass seed beneath the shrub canopies, which can substantially 

increase seeding success during favorable establishment years (figs. 7 

and 8). Pre-fire sagebrush dominance can be estimated using readily 

available 1 m2 aerial imagery (National Agricultural Imagery Program) 

with the assumption that the higher the density of sagebrush, the 

higher the fire severity. 
20 USDA Forest Service RMRS-GTR-338. 2015

Pre-Wildfire Composition and Structure Unknown

1. If the herbaceous composition prior to the wildfire is unknown, the following 

indicators can help approximate the abundance of perennial grasses and 

forbs prior to the wildfire.

a. Based on the ecological site description, what perennial grasses would be 

present in the reference state? 

b. What is the potential for invasive annual grasses and other invaders to 

increase on the burned area based on ecological site characteristics (for 

example, soil temperature/moisture regime, elevation, and aspect), seed 

source (on or off site), and current and future disturbances, including 

livestock grazing? Is the potential for invasives low, moderate, or high? (If 

the ecological site is mesic to warm-frigid, resistance to invasive annual 

grasses will largely depend on the post-wildfire abundance of perennial 

grasses and forbs.)

c. What is the density of germinable invasive annual grass seeds on the soil 

surface? Where shrub cover is relatively high (>15 percent) resulting in 

high fire intensity, the majority of cheatgrass seed under shrub canopies 

is usually consumed, decreasing cheatgrass competition and increasing 

seeding success given favorable first year conditions for establishment.

d. What is the density of burned and unburned deep-rooted perennial grass 

crowns (see Appendix 4 for indicators of burn severity, which will influence mortality)?

e. What is the density of shallow-rooted perennial grass crowns?

f. Is the general disturbance and land use history known for the burned area 

(for example, local knowledge, utilization studies, and trend plots)?

i. If not known, what would past grazing distribution and intensity likely 

have been based on topography, available water, and location of 

settlements (areas around towns and homesteads would have likely 

seen heavier grazing)?

1. If historical grazing was likely improper and soil temperature/moisture regimes are mesic/dry-aridic, aridic, or xeric, native perennial 

grasses were likely severely depleted to absent, and annual grasses 

were likely dominant or co-dominant with native perennial grasses 

and forbs.

2. If historical grazing was improper and the soil temperature/moisture regimes are frigid/xeric, native perennial grasses were likely 

depleted and invasive annual grasses were likely present but not 

dominant.
USDA Forest Service RMRS-GTR-338. 2015 21

ii. What other types of disturbances or land uses have potentially impacted 

vegetation structure and composition (for example, off-highway vehicle 

use, and wild horse and burro use)?

g. If there are similar adjacent unburned areas or unburned islands within the 

fire perimeter, what is their plant composition? When comparing burned 

and unburned areas, it is necessary to ensure that the areas are the same 

or similar ecological sites. Be careful in extrapolating, as unburned areas 

may have contained different fuel loads as a result of differences in soils, 

disturbance history, and other factors.

2. What is the ability of plant species on the burned area to persist following 

wildfire?

a. How fire tolerant/persistent are the native species on the ecological site 

and how will this potentially influence post-wildfire composition?

i. Broadleaf grasses such as bluebunch wheatgrass are usually more fire 

tolerant than fine leaf grasses (e.g., Thurber needlegrass).

ii. Perennial grasses and forbs that are rhizomatous or have their crown 

buds below the soil surface are usually fire tolerant and quickly recover 

after fire.

b. What is the post-wildfire persistence of species of concern, and what is 

their potential for recovery?

i. The most common sagebrush 

species and subspecies are fire 

intolerant (Artemisia tridentata 

subspecies, A. arbuscula, and A. 

nova). Recovery depends on seedling establishment and is closely 

linked to ecological site characteristics, available seed source, 

pre-and post-wildfire weather, 

and subspecies of sagebrush.

3. If piñon and/or juniper were present on 

the site, what was the woodland phase? 

Woodland phase affects understory composition in addition to fuel loads and 

structure, which affects fire severity.

a. Phase III woodlands can result in low perennial grass and forb cover unless 

soils are moderately deep to deep with minimal development of a restrictive layer (for example, argillic) that limits water infiltration through the soil 

profile.

b. Based on Appendix 4, what was the fire severity? Phase III woodlands 

usually burn at high severity resulting in high perennial grass and forb 

mortality.

Fire persistence (tolerance 

or avoidance) of most 

herbaceous vegetation can 

often be determined from visible 

morphological traits (table 4). 

Persistence of shrubs depends 

on the ability to re-sprout (table 

5), and new plant establishment 

depends on seed banks, external 

seed sources, and favorable years 

for germination and growth. 
22 USDA Forest Service RMRS-GTR-338. 2015

Table 4. Examples of some common perennial forbs in the Great Basin and Columbia River Plateau Regions 

and their tolerance to fire as related to their growth form.

Tolerant

(damage none to slight)

Intolerant

(damage moderate to severe)

Buds below ground

common yarrow (Achillea millefolium)

mountain dandelion (Agoseris spp.) 

onion (Allium sp.)

aster sp. (Aster sp.)

milkvetch sp. (Astragalus sp.)

arrowleaf balsamroot (Balsamorhiza spp.)

mariposa lilly (Calochortus spp.)

hawksbeard (Crepis spp.)

fleabane (Erigeron spp.)

sticky purple geranium (Geranium viscosissimum)

old man’s whiskers (Geum triflorum)

biscutroot (Lomatium spp.) 

lupine sp. (Lupinus spp.)

bluebells sp. (Mertensia spp.)

woolly groundsel (Pakera cana)

penstemon spp. (Penstemon spp.)

longleaf phlox (Phlox longifolia)

lambstongue ragwort (Senecio integerrimus)

largehead clover (Trifolium macrocarpum)

death camus spp. (Zigadenus spp.)

mules ear (Wyethia amplexicaulis)

Buds above ground

pussytoes (Antennaria spp)

sandwort (Arenaria spp.)

matted buckwheat (Eriogonum caespitosum)

Douglas buckwheat (Eriogonum douglasii)

parsnip buckwheat (Eriogonum heracleoides)

slender buckwheat (Eriogonum microthecum)

rock buckwheat (Eriogonum sphaerocephalum)

sulfur-flower buckwheat (Eriogonum 

umbellatum)

spiny phlox (Phlox hoodii)

Derived from Blaisdell 1953; Pechanec and others 1954; Mueggler and Blaisdell 1958; Lyon and Stickney 

1976; Klebenow and Beall 1977; Wright and others 1979; Volland and Dell 1981; Bradley and others 1992; 

Pyle and Crawford 1996; Riegel and others 2006; USDA-Forest Service 2013.

3—Wildfire Severity

Fire severity is a function of fuel characteristics, weather, and topography.

Assessing Wildfire Severity 

1. Was severity (Appendix 8) of the wildfire low, moderate, or high? Fire 

severity can be estimated after the wildfire by evaluating the percentage 

and types of aboveground organic matter consumed (Appendix 4) or using 

remote sensing models that portray burn severity across the entire burn 

(http://www.fs.fed.us/eng/rsac/baer/ ).

2. What is the size and distribution of unburned patches? What is the distribution of low, moderate, and high severity burned areas?
USDA Forest Service RMRS-GTR-338. 2015 23

Table 5. Potential response of common shrubs to fire in the Great Basin and Columbia River Plateau Regions.

Tolerant Moderately tolerant Intolerant

silver sagebrush (Artemisia cana) (s)

snowfield sagebrush (Artemisia 

spiciformis) (s)

aspen (Populus tremuloides) (s)

green rabbitbrush (Chrysothamnus 

viscidiflorus) (s)

wax current (Ribes cereum) (s)

desert gooseberry (Ribes velutinum) (s)

Woods’ rose (Rosa woodsii) (s)

mountain snowberry (Symphoricarpos 

oreophilus) (s)

horsebrush sp (Tetradymia sp.) (s)

serviceberry (Amelanchier alnifolia) (s)

Stansbury cliffrose (Purshia 

stansburiana) (s)

desert bitterbrush (Purshia tridentata var. 

glandulosa) (s)

Nevada Mormon tea (Ephedera 

nevadensis) (s)

greasewood (Sarcobatus velutinus) (s)

Torrey’s saltbush (Atriplex torreyii) (s)

Gardner’s saltbush (Atriplex gardnerii) (s)

Sagebrush Steppe

rubber rabbitbrush 

(Ericameria nauseosus) (s)

three-tip sagebrush 

(Artemisia tripartita) (ws)

Desert shrub

low sagebrush (Artemisia cana) (ns)

black sagebrush (Artemisia nova) (ns)

big sagebrush (Artemisia tridentata) (ns)

curl-leaf mountain mahogany 

(Cercocarpus ledifolius) (ws)

antelope bitterbrush (Purshia tridentata

var. tridentata) (ws)

Mexican cliffrose (Purshia mexicana) 

(ws)

broom snakeweed (Guiterrezia 

sarothrae) (ws)

spiny hopsage (Grayia spinosa) (ws)

bud sagebrush (Picrothamnus 

desertorum) (ns)

shadscale (Atriplex confertifolia) (ns)

fourwing saltbush (Atriplex canescens) 

(ws) 

winterfat (Krascheninnikovia lanata) (ws)

S = sprouter; ws = weak sprouter; ns = non-sprouter. Derived from Blaisdell 1953; Mueggler and Blaisdell 1958; 

Nord 1965; Wright 1972; Wright and others 1979; West 1994.

3. What were the weather conditions during the wildfire?

4. What were the fuel loads, if known?

a. What was the general structure of the vegetation: grassland; open 

shrub-grassland; shrub-grassland; dense shrubland; or phase I, II, or III 

woodland?
24 USDA Forest Service RMRS-GTR-338. 2015

i. Wildfire severity in shrub grassland is most commonly low to 

moderate.

b. Were the surface fuels adequate to carry a wildfire across a shrubland 

community or woodland?

i. If shrub cover was relatively high (>15 percent), and invasive annual grasses were present, a large portion of the invasive annual 

grass seed bank is typically 

consumed, resulting in low 

abundance in the first postwildfire year (see section 

2. 1d).

c. If juniper and/or piñon occupy 

the area, what is the woodland phase (I, II, or III)? Fuel 

structure in late phase II and 

especially phase III requires severe weather conditions (low humidity, 

high temperatures, and wind) to carry fire due to lack of horizontal 

As resilience to disturbance(s) 

and resistance to invasive annual 

grasses and other invasives 

decrease, fire severity becomes 

of greater concern because it can 

cause irreversible damage.

Figure 9. Fire behavior, including intensity, duration, and rate of spread, are determined by three components: 

topography, climate and weather, and fuels. The specific traits of each of these components influence fire 

behavior and are closely related to fire severity.
USDA Forest Service RMRS-GTR-338. 2015 25

fuel continuity resulting from limited surface fuels. The combination 

of extreme weather conditions and heavy fuels typically results in 

high severity fires.

i. High fire severity in phase III woodlands can result in >80 percent 

mortality of perennial grasses and forbs.

ii. Low to moderate fire severity usually results in <20 percent mortality of perennial grasses and forbs.

4—Post-Wildfire Weather

Post-wildfire weather conditions can influence future seed production, 

seedling establishment, and recovery of plants that survive the wildfire (both 

native and invasive species). Consequently, weather can influence the type of 

post-wildfire management actions, including length of deferment from grazing or closure of wildfire areas to off-road vehicles.

1. How will post-wildfire weather influence successional pathways, and will 

additional actions or multiple interventions potentially be needed (for 

example, invasive annual grass control, seeding or reseeding, or transplanting sagebrush)?

a. Seed banks of perennial native species are often low, and seedling establishment usually only occurs during wet springs, especially on warm/

dry ecological sites.

b. Favorable weather conditions can increase establishment, productivity, 

and seed-crops of both desirable and undesirable plant species.

c. Recovery of perennial herbaceous vegetation in the first 1 to 2 years is 

typically dependent on vegetation that survived the wildfire.

d. Recovery of sagebrush is highly dependent upon nearby seed sources 

and seed in the post-fire seed bank. Successful establishment is dependent on favorable post-fire weather and limited competition from 

invasive annual grasses.

2. What is the potential for wind or water erosion in the first 1 to 2 years post 

wildfire?

Drought conditions may simply delay recovery or redirect successional 

pathways. 
26 USDA Forest Service RMRS-GTR-338. 2015

5—Post-Wildfire Grazing

1. Assuming proper livestock grazing management, how long should the 

burned area be deferred from grazing? The deferment period may vary 

across ecological sites in the area burned and, if so, the ecological site that 

is most sensitive to grazing impacts should dictate the deferment period. 

Vegetation present prior to the wildfire, wildfire severity, and if the burned 

area was reseeded also can influence length of the deferment period.

a. Deferring grazing during the active growth period for the first 2 years is 

probably adequate only for ecological sites where:

• Fire severity was low to 

moderate 

• Post-wildfire erosion is minimal

• Resilience and resistance to 

invasive annual grasses is high

• Pre-wildfire herbaceous vegetation was dominated by natives, 

and invasive annual grasses were only a minor component

• Post-wildfire monitoring indicates adequate recovery of shrubs, perennial grasses, and forbs or that seeding objectives have been met

b. Deferring grazing during the active growth period for the first 2 years is 

probably inadequate where any of following apply:

• Wildfire severity was high, 

resulting in high mortality of 

deep-rooted perennial grasses 

• Resilience to wildfire and resistance to invasive annual grasses 

are moderate to low 

• Invasive annual grasses were codominant or dominant

• Post-wildfire monitoring indicates low or slow recovery of perennial 

grasses and forbs or that seeding objectives have not been met

2. What is the post-wildfire level of control of grazing in terms of duration, 

stocking rates, distribution, and season of use? Appropriate grazing management after the post-fire livestock deferment period is necessary to maintain 

the recovered or seeded plant community.

3. What are the potential impacts of recreational use, wild horses and burros, 

and wildlife (for example, elk use in treated areas with increased grass 

abundance)?

The lack of adequate 

deferment or proper long-term 

grazing management can have a 

dramatic effect on the resilience 

and resistance of the burned area 

(fig. 10).

The amount of time for postwildfire grazing deferment that is 

necessary for recovery is largely 

determined by wildfire severity, 

ecological site characteristics, 

pre-wildfire plant composition 

and structure, and post-wildfire 

weather.
USDA Forest Service RMRS-GTR-338. 2015 27

Figure 10. Comparison of adjacent (A) exclosed and (B) grazed areas that were treated with prescribed fire 

7 years before the photos were taken. The ecological site is a cool-mesic/aridic bordering on xeric Wyoming 

big sagebrush/Thurber’s needlegrass type. The site is in Nevada at an elevation of 7,500 to 7,800 ft and was 

grazed prior to treatment. Fencing was installed after the fire. Inappropriate grazing resulted in loss and/or 

limited recovery of deep-rooted perennial grasses and the dominance of non-native invasives, as shown in 

photo B (photographs by Robin Tausch).

A

B
28 USDA Forest Service RMRS-GTR-338. 2015

6—Monitoring and Adaptive Management

A monitoring plan should be implemented to direct adaptive management 

and provide information for future recovery plans or vegetation treatments.

1. Do the monitoring protocols measure the project objectives? See USGS 

publication “Monitoring Post-Fire Vegetation Rehabilitation Projects: A 

Common Approach for Non-Forested Ecosystems” (http://pubs.usgs.gov/

sir/2006/5048/).

2. Are the monitoring methods consistent with those being used elsewhere?

3. Is a plan in place for data entry and analyses that is consistent across the 

agency(s) (for example, the Land Treatment Digital Library (http://ltdl.

wr.usgs.gov/)?

4. Is there a mechanism for summarizing the results and incorporating the 

relevant information into the planning process?

5. Is there a mechanism to share monitoring results with others implementing similar treatments on similar sites? The Joint Fire Science Program’s 

Great Basin Fire Science Exchange 

can assist with this effort (http://

www.gbfiresci.org). Monitoring provides essential 

information on post-wildfire 

outcomes that can be used to 

adjust future prescriptions and to 

determine if post-treatment actions 

are needed.
USDA Forest Service RMRS-GTR-338. 2015 29

Post-Wildfire Vegetation 

Treatment Assessment

State and Transition Models

State and transition models (STMs) can be used to illustrate potential successional pathways that result from wildfire and follow-up vegetation treatment 

scenarios. Appendix 5 provides STMs that represent five generalized ecological types for big sagebrush in the Great Basin and Columbia River Plateau 

regions. For many areas, specific ESDs and STMs are available (see: http://

www.nrcs.usda.gov/wps/portal/nrcs/main/national/technical/ecoscience/

desc/).

Identification of the specific or generalized big sagebrush ecological sites 

and knowing (or estimating) the pre-wildfire vegetation composition and 

structure will help to determine the need and suitability of the area for seeding (Appendix 6) and the plant species that should be considered for the seed 

mix. ESDs also provide information related to relative resilience and resistance to invasive annual grasses and the associated STMs provide information 

on potential successional pathways.

Land Unit Evaluation Score Sheet

Appendix 7 provides a score sheet that can be used to quickly evaluate the 

level of ecological site resilience to disturbance and resistance to invasive annual grasses, and to determine the suitability of the area for seeding and the 

need for seeding. It is based on four components: (1) soil temperature regime, 

(2) soil moisture regime, (3) pre-wildfire plant composition, and (4) fire severity. Site characteristic scores, which evaluate soil temperature and moisture 

regimes, estimate the suitability of the area for seeding. Pre-wildfire vegetation and fire severity determine the need for seeding. Each major ecological 

site (or group of similar ecological sites) within the proposed burned area is 

evaluated with a separate score sheet. Scores are not absolute and should 

be used only as guidelines. The score sheet values can be modified when 

quantitative data and/or scientific studies provide better information or when 

the results of monitoring of similar treatments become available for the same 

ecological sites. 

USDA Forest Service RMRS-GTR-338. 2015 29
30 USDA Forest Service RMRS-GTR-338. 2015

Seeding: Suitability and Need

Ecological criteria used to determine whether or not to seed are: (1) ecological 

site characteristics that strongly contribute to the degree of success (seeding 

success increases with resilience), (2) the ecological site’s resistance to invasive annual grasses, (3) the composition and abundance of native perennial 

grasses and forbs that likely survived the wildfire, and (4) the pre-wildfire 

abundance of invasive annual grasses and post-fire seed bank survival. 

Ecological Site Characteristics

The level and probability of successful seeding will vary across ecological 

sites. Success of seeding natives on ecological sites with mesic/aridic (warm/

dry) (<10 inches ppt) soil temperature/moisture regimes is very low (accumulative soil temperature and moisture score <10) (fig. 11). Using introduced 

wheatgrasses or a half-shrub such as forage kochia (Kochia scoparia) may increase seeding success on these sites, but may not meet resource objectives. 

Seeding species such as crested wheatgrass and forage kochia can reduce the 

threat of fire and competition from invasive annual grasses. Seeding success 

on cool-mesic/aridic ecological sites (10 to 12 inches ppt) is usually mixed 

and is highly dependent on annual moisture in the first 2 to 3 post-fire years 

(cumulative soil temperature and moisture score = 12 to 15) (fig. 12) and the 

methods used to apply the seed (for example, drilling vs aerial or broadcast 

seeding). Seeding success on frigid/xeric (cool/moist) ecological sites (cumulative soil temperature and moisture score = 14 to 17) is typically high. 

Environmental factors such as precipitation timing and amount, which cannot 

be controlled or predicted, can affect seeding success even on cool-mesic/aridic 

and frigid/xeric ecological sites. Drill seeding is much more effective than 

aerial or broadcast seeding (without a follow-up coverage treatment), especially on mesic/aridic soil temperature/moisture regimes where establishment 

success is very low. 
USDA Forest Service RMRS-GTR-338. 2015 31

Figure 11. Post-wildfire response for adjacent (A) seeded and (B) unseeded areas that burned 9 years earlier 

in 2002. The ecological site is a warm-mesic/dry-aridic Wyoming big sagebrush/Indian ricegrass-Sandberg 

bluegrass type located at an elevation of 5,000 ft southeast of Gerlach, Nevada. Native herbaceous vegetation 

prior to the burn was probably severely depleted to absent and the presence of a sagebrush canopy was 

unknown. Based on the score card (Appendix 7), the soil temperature + moisture score is 9, and the total 

score is 9 to 12 depending on pre-fire vegetation. Limited moisture and warm temperature result in low 

suitability for seeding and resilience to disturbance. The treated area (A) was drill seeded in the fall following 

the fire to native grasses and (B) was not seeded. Cover in the seeded area (A) is 0% deep rooted perennial 

grasses, 89% cheatgrass, 6.7% native shrub, and 0% non-native shrub. Cover in the unseeded area (B) is 0% 

native deep-rooted perennial grasses, 61% cheatgrass, 3.3% native shrub, and 6% non-native shrub. 

B

A
32 USDA Forest Service RMRS-GTR-338. 2015

Figure 12. Post-wildfire response for adjacent (A) seeded and (B) unseeded areas that burned 9 years 

earlier. The ecological site is a cool-mesic/aridic Wyoming big sagebrush/bluebunch (10 to 12 inch PZ) type 

located south of Rome, Oregon, at an elevation of 5,000 ft. Native herbaceous vegetation prior to the burn was 

probably severely depleted to absent, and the presence of a sagebrush canopy was unknown. Based on the 

score card (Appendix 7), the soil temperature + moisture score is 12, and the total score is 12 to 15 depending 

on pre-fire vegetation. The treated area (A) was drill seeded in the fall following the fire to native grasses. 

Cover in the seeded area (A) is 23% native deep-rooted perennial species and 65% cheatgrass; cover in the 

unseeded area (B) is 7% native deep-rooted perennial and 69% cheatgrass.

A

B
USDA Forest Service RMRS-GTR-338. 2015 33

Need

Seeding should be considered on burned areas where perennial herbaceous 

species were severely depleted to absent; cheatgrass seed bank is low; or fire 

severity was high, resulting in high mortality of perennial herbaceous species, 

and where ecological site characteristics are suitable for success (cumulative 

soil temperature and moisture usually scores >10). However, for areas with 

scores between 10 and 15 that have sufficient perennial herbaceous species 

to recover following wildfire, seeding with introduced species or aggressive cultivars will likely retard or prevent recovery of the native community. 

Considerations for evaluating the need to seed (fig. 8) are:

1. Seeding of herbaceous vegetation should not be considered for areas in 

the burn where perennial grasses and forbs were common in the area prior 

to the wildfire and fire severity was low to moderate. Recovery may occur 

in high severity burn areas but the degree of recovery is lower than in the 

moderate to low categories.

2. Seeding may not be necessary on low to moderate severity burned areas 

where native herbaceous perennial grasses are depleted but are likely >2/

m2 (10 ft2) on frigid-xeric and >3/m2 (10 ft2) on mid to cool mesic/aridic (10 

to 12 inches ppt). However, if invasive annual grasses have the potential to 

substantially increase on areas with mid- to cool-mesic soil temperatures 

and >10 inches ppt, and native perennial grasses are depleted (<3/m2 [10 

ft2]), seeding should be a strong consideration.

3. If native herbaceous perennial grasses are severely depleted, (<2/m2 [10 

ft2] on frigid/xeric and <3/m2 (10 ft2) on mid to cool-mesic/aridic temperature/moisture regimes) and/or fire severity was high, seeding should be 

considered.

4. If native perennial grasses are severely depleted (<3/m2 [10 ft2]) on warmto mid-mesic/aridic or mesic/xeric (<10 inches ppt) regimes, establishment 

success of native seed will likely be low. Seeding may still be a consideration in areas of conservation concern, but more than one intervention 

may be required.

a. The potential for rapid reintroduction of invasive annual grasses on 

severely depleted burned areas will depend on the ecological site’s resistance to invasive annual grasses, seed source available following the 

wildfire, and post-wildfire moisture availability.

b. Most invasive annual grass seed under shrub canopies is consumed by 

wildfire on areas with >15 percent shrub cover, often resulting in low 

plant abundance in the first post-wildfire growing season. However, increased soil resources result in high growth and reproduction of invasive 
34 USDA Forest Service RMRS-GTR-338. 2015

annual grasses, leading to a large increase in abundance the second or 

third year after wildfire.

c. Areas that are dominated by sagebrush with cheatgrass in the understory often provide a 1-year window opportunity to seed due to the higher 

intensity fires resulting in the consumption of cheatgrass seed.

5. Seeding big sagebrush? 

a. Seeding Wyoming big sagebrush on areas with mid- to cool-mesic soils 

and >10 inches ppt should also be a consideration. However, seeding 

success is often very low when seed is broadcast or applied with a 

rangeland drill. Seeding methods that result in a firm seedbed, such as 

a Truax Roughrider® drill with cultipacker wheels, can result in increased 

establishment of sagebrush. Planting seedlings or distributing straw 

mulch over the sagebrush seed is costly but may be a consideration in 

areas of conservation concern.

b. Sagebrush cover in burned areas previously occupied by mountain big 

sagebrush usually recovers to pre-wildfire conditions within 25 to 35 

years in the absence of seeding. Seeding or transplanting mountain big 

sagebrush may be a consideration to increase the rate of recovery or 

connectivity in areas of conservation concern.

c. Post-fire establishment of basin big sagebrush is usually faster than 

Wyoming big sagebrush but slower than mountain big sagebrush. 

Seeding decisions should be based on local experience.

6. Recovery of low sagebrush (Artemisia arbuscula) on shallow claypan soils, 

where Sandberg’s bluegrass is the potential dominant herbaceous species 

is typically very slow.

7. Recovery of black sagebrush, which typically grows on shallow mesic/aridic 

soils, is usually very slow.

8. Success of seeding native shrubs and herbaceous species on warm- to midmesic soils with <10 inches of precipitation is low.

Recovery of big sagebrush is largely determined by ecological site characteristics, subspecies, competition from invasive annual grasses, post-wildfire 

weather conditions, and size and complexity of the wildfire, which effects 

distance to seed source and seed pools present immediately after the wildfire.
USDA Forest Service RMRS-GTR-338. 2015 35

When seeding is not likely to meet the objectives of increasing or restoring 

resilience to disturbance and resistance to invasive annual grasses following 

treatment, a logical decision is “not to treat.” Exceptions may include:

1. Critical habitat where sufficient funds exist for repeated interventions and 

integrated strategies can be used such as prescribed-fire treatments followed by control of invasive annual grasses and revegetation.

2. Critical portions of a watershed where treatment is necessary to prevent 

erosion or introduction of an invasive annual grass seed-source. Also, areas 

where integrated strategies can be used such as prescribed-fire treatments 

followed by control of invasive annual grasses and revegetation.
36 USDA Forest Service RMRS-GTR-338. 2015
USDA Forest Service RMRS-GTR-338. 2015 37

Selecting Areas Within the 

Burn for Seeding

What, where, and how much area to seed across a burn area is usually determined by priorities, need, potential for success, and available resources, 

including funding and availability of seed adapted to the area. Questions to 

address when selecting areas to be treated include:

1. What are the chances of seeding success based on the area’s resilience to 

disturbance and resistance to invasive annual grasses, which are closely 

linked to ecological site characteristics?

2. What is the need for seeding based on plant community composition and 

structure prior to the wildfire and fire severity? 

3. Does the area provide important habitat for animal and/or plant species of 

concern? 

4. Can reseeding increase the landscape connectivity for species of concern? 

5. Are portions of the burn major sources of sediment to nearby streams, or 

do they have high erosion potential?

6. What is the treatment cost?

7. What seeding methods can be used based on steepness of slope, rockiness, 

etc.

8. Is retreatment likely to be needed and, if so, is it an option?

9. Can post-treatment management be modified to attain project objectives? 

For example, can livestock grazing be deferred long enough for the site 

to recover, and can appropriate grazing be implemented to maintain the 

treatment objectives once the decision to resume grazing has been made?

USDA Forest Service RMRS-GTR-338. 2015 37
38 USDA Forest Service RMRS-GTR-338. 2015
USDA Forest Service RMRS-GTR-338. 2015 39

Key References

Chambers, J.C.; Bradley, B.A.; Brown, C.S.; D’Antonio, C.; Germino, M.J.; Grace, J.B.; 

Hardegree, S.P.; Miller, R.F.; Pyke, D.A. 2014a. Resilience to stress and disturbance, 

and resistance to Bromus tectorum L. invasion in cold desert shrublands of western 

North America. Ecosystems. 17: 360–376.

Miller, R.F.; Bates, J.D.; Svejcar, T.J.; Pierson, F.B.; Eddleman, L.E. 2005. Biology, 

ecology, and management of western juniper (Juniperus occidentalis). Tech. Bull. 

152. Corvallis, OR: Oregon State University Agricultural Experiment Station. 77 p.

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

field guide: asking the right questions to select appropriate management actions. 

Circular 1321. Reston, VA: U.S. Department of the Interior, Geological Survey. 59 p.

Miller, R.F.; Knick, S.T.; Pyke, D.A.; Meinke, C.W.; Hanser, S.E.; Wisdom, M.J.; Hild, 

A.L. 2011. Characteristics of sagebrush habitats and limitations to long-term 

conservation. In: Knick, S.T.; Connelly, J.W., eds. Greater sage-grouse: ecology 

and conservation of a landscape species and its habitats. Studies in Avian Biology. 

Berkley, CA: University California Press: 38: 146–184.

Parson, A.; Robichaud, P.R.; Lewis, S.A.; Napper, C.; Clark, J.T. 2010. Field guide for 

mapping post-fire soil burn severity. Gen. Tech. Rep. RMRS-GTR-243. Fort Collins, 

CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research 

Station. 49 p.

Pyke, D.A. 2011. Restoring and rehabilitating sagebrush habitats. In: Knick, S.T.; 

Connelly, J.W., eds. Greater sage-grouse: ecology and conservation of a landscape 

species and its habitats. Studies in Avian Biology. Berkeley, CA: University of 

California Press. 38: 531–548.

Shultz, L.M. 2012. Pocket guide to sagebrush. Petaluma, CA: Point Blue Conservation 

Science. 85 p.

Tausch, R.J.; Miller, R.F.; Roundy, B.A.; Chambers, J.C. 2009. Piñon and juniper field 

guide: asking the right questions to select appropriate management actions. 

Circular 1335. Reston, VA: US. Department of the Interior, U.S. Geological Survey. 

http://pubs.usgs.gov/circ/1335/. (April 13, 2015).

USDA Forest Service RMRS-GTR-338. 2015 39
40 USDA Forest Service RMRS-GTR-338. 2015
USDA Forest Service RMRS-GTR-338. 2015 41

Literature Cited

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the upper Snake River Plains. Tech. Bull. 1075. Washington, DC: U.S. Department of 

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Forest Service, Intermountain Forest and Range Experiment Station. 128 p.

Chambers, J.C.; Bradley, B.A.; Brown, C.S.; D’Antonio, C.; Germino, M.J.; Grace, J.B.; 

Hardegree, S.P.; Miller, R.F.; Pyke, D.A. 2014a. Resilience to stress and disturbance, 

and resistance to Bromus tectorum L. invasion in cold desert shrublands of Western 

North America. Ecosystems. 17: 360–376.

Chambers, J.C.; Miller, R.F.; Board, D.I.; Grace, J.B.; Pyke, D.A.; Roundy, B.A.; Schupp, 

E.W.; Tausch, R.J. 2014b. Resilience and resistance of sagebrush ecosystems: 

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Basin rangelands. In: Proceedings of the 1977 Rangeland Management and Fire 

Symposium. Missoula, MT: University of Montana Press: 59–62.

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3–11.

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effects on vegetation and soils in the Great Basin Region: response and ecological site 

characteristics. Gen. Tech. Rep. RMRS-GTR 308. Fort Collins, CO: U.S. Department 

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I, II, III. RMRS-GTR-136. Fort Collins, CO: U.S. Department of Agriculture, Forest 

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spraying, and railing sagebrush. Journal of Range Management. 11: 61–66.

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307–334.

Parson, A.; Robichaud, P.R.; Lewis, S.A.; Napper, C.; Clark, J.T. 2010. Field guide 

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prescribed fire in sagebrush-bitterbrush. Journal of Range Management. 49: 320–

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northeastern Plateaus bioregion. In: Sugihara, N.G.; Borchert, M.; van Wagtendonk, 

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5370-211. 1524 p.

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system. http://www.fs.fed.us/database/feis/plants/index.html. (April 13, 2015).

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interpreting soil surveys. Agric. Handb. 436. http://www.nrcs.usda.gov/Internet/

FSE_DOCUMENTS/nrcs142p2_051232.pdf. (April 13, 2015).

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apps.cei.psu.edu/mlra/. (April 13, 2015).
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usda.gov/plantguide/pdf/pg_artr2.pdf. (April 13, 2015).

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vegetation. Range Management and Aviation and Fire Report 6. Portland, OR: U.S. 

Department of Agriculture, Forest Service, Pacific Northwest Region. 23 p.

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Temperate deserts and semi-deserts. Amsterdam, the Netherlands: Elsevier 

Publishing Company: 351–374.

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Experiment Station. 48 p.
44 USDA Forest Service RMRS-GTR-338. 2015

Component Characteristics

Ecological site 

(figs.1, 2, and 3)

Regional location (MLRA)

Climate

Topography

Elevation, aspect, slope, landform, and landscape position (consider 

how topography affects water movement and storage, and heat loads)

Soils

Soil temperature/moisture regimes

Depth, texture, percentage of organic matter, and structure

(consider factors that influence water storage and availability)

Potential vegetation within the reference state

Species composition and structure (biomass, cover, density, etc.)

Potential production in favorable, average, and unfavorable years 

Current vegetation

Vegetation productivity (annual production)

Species composition and structure relative to the ecological site 

description

Fire-tolerant and non-tolerant species (morphology)

Native and invasive species

 Residual perennial herbaceous species are often more important for

 recovery than seed banks and seed sources

Potential for invasive species 

Environmental characteristics of the site (mesic to warm frigid

 south-facing slopes, etc.)

 Relative abundance of perennial herbaceous species

On site and adjacent invasive seed banks and potential seed ra

Fuel load and structure

Woodland phase (fire severity increases with increased tree biomass)

Fine surface fuels and structure (biomass, continuity, and packing 

 ratios)

Woodland age structure (pre- and post-settlement tree densities)

Amount and distribution of bare ground and gap size between perennial 

plants Amount and distribution of biological soil crusts

At-risk-phase?

Appendix 1: Primary Components and Attributes That Influence 

Resilience to Disturbance, Resistance to Invasive Annual Grasses, 

and Successional Trajectories.
USDA Forest Service RMRS-GTR-338. 2015 45

Disturbance history 

(figs. 1 and 3; pre- and post)

Severity and frequency

Time since last event 

Type

Fire

Mechanical

Drought

Herbivory, including livestock, native and introduced herbivores 

Disease, snow-mold, fungus, etc.

Insects

Fire severity (fig. 7)

Fuels

Topography 

Fire weather

Season (linked with fire weather and plant phenology)

Current vegetation (fuel abundance, continuity, and structure)

Fire type

Ground, surface, crown, head fire, backfire, and backing fire

Pre-wildfire weather

(previous 1 to 3 years)

Timing and amount of precipitation

Temperatures (primarily extremes)

Consider how it has influenced:

 Fuels

 Seed banks

 Pre-treatment species composition and vigor
46 USDA Forest Service RMRS-GTR-338. 2015

Appendix 2: Examples of Elevation Breaks and Plant Indicators 

for Soil Temperature Regimes in Two MLRAs

Soil 

temperature 

regime

Elevation (ft)a PPT

(in)

Moisture 

regime

Indicator 

plantsb

Ecological 

zones

MLRA 23 MLRA 28B

Mesic

Warm <3000 4,000–6,000 4–8 Typic 

aridic

Arsp, Atco, 

Krla, Heco, 

Achy

Desert 

basins

Cool 3,000–4,000 5,500–6,500 8–12 Aridic 

bordering 

xeric

Arno, Artrw, 

(few Juos 

or Juoc), 

Acth

Sagebrush 

semi-desert

Frigid

Warm 4,000–5,000 6,000–8,000 12–14 Xeric 

bordering 

aridic

Arno, Arar, 

Artrv, Artrw, 

Juos or 

Juoc, Pimo, 

Acth

Upland 

sagebrush, 

juniper, 

piñon 

Cool 5,000–6,000 7,500–8,200 14+ Typic xeric Artrv, 

Symph, 

Amal, 

Pimo, 

Juos or 

Juoc, Feid, 

Acne, snow 

pocket Potr

Upland 

mountain 

sagebrush, 

piñon, 

juniper 

Cryic

Warm 6,000–7,500 

(8,000)

8,200–9,600 16+ Typic xeric Artrv, 

Arsp8, Arar, 

Symph, 

Amal,Cele, 

Abco, Potr

Mountain 

brush

Cool 8,000–9,000 9,300–10,600 18+ Typic xeric Pien, Piar, 

Pifl

High 

mountain

Cold >9,000 10,600–13,061 20+ Xeric 

bordering 

aridic

Alpine 

plants

Subalpine 

and alpine

a Elevation is usually adjusted 500 ft for north (-) or south (+) aspects, and elevation breaks change from 

the north to south ends of the MLRA. Elevation and indicator species should be fine-tuned for a specific 

management area. It is also important to consider that changes along elevation gradients or from north to 

south locations within an MLRA are usually gradual and are not defined by distinct boundaries. 

b Plant codes: Abco = Abies concolor, Achy = Achnatherum hymenoides, Acne = Acnatherum nevadense, 

Acth = Achnatherum thurberianum, Amal = Amelachier alnifolia, Arar = Artemisia arbuscula, Arno = 

Artemisia nova, Arsp = Artemisia spinescens, Arsp8 = Artemisia spiciformis, Artrv = Artemisia tridentata

spp. vaseyana, Artrw = Artemisia tridenatata spp. wyomingensis, Atco = Atriplex confertifolia, Cele = 

Cercocarpus ledifolius, Feid = Festuca idahoensis, Heco = Hesperostipa comata, Juoc = Juniperus 

occidentalis, Juos = Juniperus osteosperma, Krla = Krascheninnikovia lanata, Piar = Pinus aristata, Pifl = 

Pinus flexilis, Pimo = Pinus monophylla, Symph = Symphoricarpos sp., Potr = Populus tremuloides.
USDA Forest Service RMRS-GTR-338. 2015 47

Appendix 3: What is the Meaning of a Soil Family Name? 

Soil Family Names

In general, soil family names ending in “olls” are Mollisols indicating that they have a minimum 

of 1 percent organic matter. Soils ending in “ids” are Aridisols. They contain <1 percent organic 

matter, usually occur in aridic precipitation zones, and are less productive than Mollisols. Both 

soil orders are common in the Great Basin. Examples of naming protocols for Mollisols and 

Aridisols follow.

1 Course sandy loam mixed mesic aridic Typic Haploxerolls

2 Clayey smectic frigid lithic xeric Haplargids

3 Fine loamy mixed super active xeric Argicryolls

4 Loamy skeletal mixed frigid Pachic Haploxerolls

Soil texture / temperature / moisture

Soil 1: Warm (mesic), dry (aridic) soil with an aridic moisture regime that is approaching xeric 

(xer for xeric) or 12 inches of annual ppt. This soil has the lowest potential resilience to disturbance and resistance to invasives due to its mesic/aridic soil temperature/moisture regime.

Soil 2: A cool (frigid), moist (xeric), shallow (lithic) soil with accumulation of clay in the B horizon (argi for argillic layer) and >12 inches of annual ppt. This soil has the lowest potential 

infiltration rates due to the presence of an argillic layer and the lowest storage potential due 

to a shallow soil depth (lithic for shallow) and <1 percent organic matter content.

Soil 3: A cold (cry for cryic)/moist (xeric, >12 inches of annual ppt) soil with accumulation of clay 

(argi) in the B horizon. This soil has the highest potential resistance to invasive species due to 

the cold temperature regime. Potential resilience will usually decline along a gradient from 

warm-cryic to cold-cryic as a result of a shortened growing season.

Soil 4: A moist (xeric), cool (frigid), rocky (skeletal) soil. This soil has relatively high resilience 

and moderate resistant to invasives. It has the highest water capture potential of the four 

soils due to the loamy soil texture and lack of an argillic layer. 
48 USDA Forest Service RMRS-GTR-338. 2015

Soil Terms

Arigillic—Typically defined by percent increase in alluvial clay content (usually the B horizon) 

relative to the overlying soil layer (usually the A horizon). The increase in clay and abrupt 

change in texture can substantially reduce infiltration rates.

Duripan—A subsurface horizon that is cemented by alluvial (water transported) silica to the 

degree that fragments from the air-dry horizon do not slake (take in water or crumble) during prolonged soaking.

Lithic—Shallow soils over a paralithic (soft bedrock) contact or duripan (subsurface horizon 

cemented by bedrock).

Skeletal—Soils with >35 percent particle sizes >2 mm by volume.

Soil depth—Very shallow is <10 inches; shallow is 10-20 inches; moderately deep is 20-36 

inches; and deep is >36 inches.

Soil moisture regime—An important soil property that, in combination with growing season 

soil temperature, influences plant growth and biological soil processes. The moisture regime 

is based on the amount of soil moisture available during the growing season in areas with 
USDA Forest Service RMRS-GTR-338. 2015 49

cool/moist winters and hot/dry summers. Xeric (moist or >12 inches annual ppt) and aridic 

(dry or <12 inches of annual ppt) soils are characteristic of arid regions where soil is dry for at 

least half the growing season and moist for less than 90 days. Although mapped as distinct 

breaks in precipitation (<12 inches or >12 inches), soil moisture regimes, in reality, are continuous gradients that change with location and elevation. Thus, it is important to consider 

where the site fits along the gradient. For example, a site with an aridic moisture regime 

that receives 11.5 inches of ppt will often be more resilient to disturbance than an aridic 

site receiving 9 inches of ppt. For a detailed definition and description of each soil moisture 

regime, see USDA-NRCS (1999). For this field guide, we define the following soil moisture 

regimes:

Dry-aridic: <10 inches annual ppt

Aridic: 10-12 inches annual ppt

Xeric: 12-14 inches annual ppt

Moist-xeric: >14 inches annual ppt

Soil temperature regime—An important property of a soil that, along with soil moisture, influences plant growth and biological soil processes. Soil temperature is usually measured at a 

depth of 20 inches (50 cm) (or depth at the lithic or paralithic contact), which is considered 

deep enough to reflect seasonal temperatures and not daily cycles. Since measurements 

of seasonal soil temperatures are spatially limited across the Great Basin, soil temperature 

regimes are estimated based on seasonal air temperatures, which are largely influenced by 

location, elevation, and aspect. When soils are mapped, temperature regimes are most commonly based on elevation and aspect, which are adjusted for each sub-region (MLRA). For a 

detailed definition and description of each soil regime, see USDA-NRCS (1999). 

Mesic (warm)—indicator species are Wyoming big sagebrush and black sagebrush. Mesic 

soils have low relative resistance to invasives compared to frigid and cryic soils. They also 

are considered to have lower resilience.

Frigid (cool)—indicator species are mountain big sagebrush, piñon pine, and low sagebrush 

on shallow soil, but black sagebrush and, occasionally, Wyoming big sagebrush may occur on the warmer end of this soil regime or where soil moisture is limiting. Resilience to 

disturbance and resistance to invasive species are higher than on mesic soils.

Cryic (cold)—indicator species are curl-leaf mountain mahogany, white and grand fir, limber 

pine, lodgepole, and white bark pine, which typically intermingle with mountain big and 

low sagebrush. Resilience is high on the warm end of this regime but declines as temperatures become colder due to limitations on plant growth. Resistance to invasive species 

is higher than for mesic and likely frigid soils (although data are limited). Cryic soils are 

cooler in summer than frigid soils.
50 USDA Forest Service RMRS-GTR-338. 2015

Soil Temperature and Moisture Regimes

The soil terms and the precipitation ranges used in the text refer to the specific soil terms shown in the following table (personal communication with 

Steve Campbell, NRCS). For a detailed definition and description of each soil 

regime, see USDA-NRCS (1999).

Term or value used in text Soil term

- Soil temperature -

hot-mesic mesic bordering on thermic

warm-mesic mesic-typic

cool-mesic mesic bordering frigid

warm-frigid frigid bordering mesic

cool-frigid frigid bordering on cryic

warm-cryic cryic bordering on frigid

cool-cryic cryic-typic

- Soil moisture -

dry-aridic or <10 inches ppt aridic-typic

aridic or 10-12 inches ppt aridic bordering on xeric

xeric or 12-14 inches ppt xeric bordering on aridic

moist-xeric or >14 inches ppt xeric-typic
USDA Forest Service RMRS-GTR-338. 2015 51

Appendix 4: Post-Wildfire Indicators of Fire Severity

Low severity Moderate severity High severity

>75% burned sagebrush skeletons 

remaining

15 to 75% burned sagebrush 

skeletons remaining

Sagebrush basal stumps remain 

or burned below the soil surface

<25% tree foliage dead, <15% 

foliage consumption

25 to 75% tree foliage dead, 15 to 

50% foliage consumed

>75% tree foliage dead, >50% 

consumed

Tree duff blackened but little 

consumed

Majority of tree duff consumed, 

surface blackened

White ash layer beneath tree 

canopy

>2 inches blackened stubble 

remains on burned grasses

0.25 to 1 inch blackened stubble 

remains on burned grasses

Grass crowns consumed to or 

below the surface

Unburned patches >50% Unburned patches 15 to 50% Unburned patches <15%

Interspace litter consumption 

<50%

Interspace litter consumption 50 

to 80%

Interspace litter consumption

>80%, white ash deposition

Shrub canopy litter consumption 

<50%

Shrub canopy litter consumption 

50 to 80%

Shrub canopy litter consumption 

>80%, white ash deposition

Minimal ash, ground fuels 

blackened and recognizable

Thin layer of black to gray ash, 

some litter recognizable

Layer of powdery gray or white 

ash, >90% surface organics 

consumed

No fire-induced water repellency Weak to medium water repellency 

at or just below the surface

Strong water repellency at or 

below the surface

Surface soil structure

Unchanged

Surface structure slightly to not 

altered

Aggregated stability reduced or 

destroyed, surface loose and/or 

powdery

Cheatgrass seeds common with 

minimal signs of consumption 

outside of pre-fire shrub canopies

Cheatgrass seeds few to 

moderately abundant outside of 

pre-fire shrub canopies, seed 

consumption variable

Cheatgrass seeds sparse both 

inside and outside of pre-fire shrub 

canopies, seed consumption 

nearly complete

Soil and litter indicators are derived from Parson and others (2010).
52 USDA Forest Service RMRS-GTR-338. 2015

Appendix 5: State and Transition Models (STMs) for Five 

Generalized Ecological Types for Big Sagebrush (from Chambers 

and others 2014b) 

These STMs represent groupings of ecological types that are occupied by 

Wyoming or mountain big sagebrush, span a range of soil temperature/

moisture regimes (warm-dry to cold-moist), and characterize a large portion of the Great Basin and Columbia River Plateau regions: (A) Mesic/aridic 

Wyoming big sagebrush (8 to 12 inch precipitation zone [PZ]); (B) Cool-mesic 

to warm-frigid/xeric big sagebrush with piñon pine and juniper potential (12 

to 14 inch PZ), (C) Cool-mesic to cool-frigid/xeric mountain big sagebrush (12 

to 14 inch PZ); (D) Cool frigid/xeric mountain big sagebrush with piñon and 

juniper potential (12 to 14+ inch PZ); and (E) Cryic/xeric mountain big sagebrush/mountain brush (14+ inch PZ). Large boxes illustrate states that are 

comprised of community phases (smaller boxes). Transitions among states 

are shown with arrows starting with T; restoration pathways are shown with 

arrows starting with R. The “at risk” community phase is most vulnerable to 

transition to an alternative state.
USDA Forest Service RMRS-GTR-338. 2015 53
54 USDA Forest Service RMRS-GTR-338. 2015
USDA Forest Service RMRS-GTR-338. 2015 55
56 USDA Forest Service RMRS-GTR-338. 2015
USDA Forest Service RMRS-GTR-338. 2015 57
58 USDA Forest Service RMRS-GTR-338. 2015

Appendix 6: Examples of States, Phases, and Transitions 

Following Prescribed Fire Treatment for Three General Ecological 

Types in Different Phases and Precipitation Zones (PZ)

Photos are from SageSTEP plots (http://www.sagestep.org). For interpretation of resilience and resistance scores, see Appendix 7.
USDA Forest Service RMRS-GTR-338. 2015 59

Fire

6A—Warm-mesic/aridic

Wyoming big sagebrush/bluebunch wheatgrass-Sandberg bluegrass (8 to 12 inch PZ)

Reference State

Fire resistant bluebunch wheatgrass is abundant, Sandberg bluegrass fills the interspaces, and 

cheatgrass is only a trace. Although warm-mesic/aridic, the area has a high probability of a 

successful recovery following a wildfire of low to moderate severity. Resilience and Resistance 

score = 17. 

Fire

6B—Warm-mesic/aridic

Wyoming big sagebrush/bluebunch wheatgrass-Indian ricegrass (8 to 12 inch PZ)

Invaded State

2009

2012

2008 2010
60 USDA Forest Service RMRS-GTR-338. 2015

6C—Cool mesic/aridic

Basin and Wyoming big sagebrush/bluebunch wheatgrass (10 to 12 inch PZ)

Juniper potential

Mechanical

Reference State

Phase I woodland/sagebrush/perennial 

grass/forb

This site is near the reference state. 

Bluebunch wheatgrass is abundant and 

cheatgrass is only a trace. The area has 

a high probability for recovery following 

wildfire or prescribed fire without seeding. 

Resilience and Resistance score = 20. 

Fire

Grassland phase

Sagebrush/perennial grass phase
USDA Forest Service RMRS-GTR-338. 2015 61

6D—Cool frigid/xeric

Mountain big sagebrush/Idaho fescue (12 to 14 inch PZ) 

Juniper potential

Reference State

The presence of Idaho fescue indicates that this is a cool-frigid soil temperature regime. The herbaceous layer is dominated by native grasses and forbs. 

There is only a trace of invasive annuals. An Aroga moth infestation caused 

nearly 100% sagebrush mortality prior to a prescribed fire. The combination of 

good herbaceous plant cover and soil moisture/temperature regimes resulted 

in high resilience and resistance. Due to adequate cover of native grasses and 

forbs and relatively high resistance, seeding is not required on this site after 

fire. Resilience and Resistance score = 25.

Fire
62 USDA Forest Service RMRS-GTR-338. 2015

Appendix 7a: Score Sheet for Rating Resilience, Resistance 

to Annual Invasive Grasses, and the Need and Suitability for 

Seeding of an Ecological Site or Type Following Wildfire

Applicability—This score sheet is a tool for a rapid assessment of resilience 

and resistance to invasive annuals for an area-of-concern that is based largely 

on three key attributes; soil temperature, available moisture, and pre-fire 

vegetation. These three attributes are primary drivers of resilience to disturbance or vegetation management, and resistance to invasives and are a 

function of climate, topography, and soils. Stringham and others (2015) state 

that: “Many ecological sites are similar in their plant composition and other 

important physical attributes such as soils but may differ in total production 

or landscape setting. Thus, often these similar ecological sites will respond to 

the same disturbance in a similar manner. The rate of response to disturbance 

may be different but the endpoint of the change will be very similar.” Because 

the score sheet is based on the physical attributes and vegetation composition that determine resilience and resistance to invasive annuals, it has 

widespread applicability.

Adaptation—It may be possible to further adapt the score sheet to a specific MLRA or ecological site as additional information becomes available. 

Attributes specific to the MLRA and/or ecological site, such as timing of moisture, can modify the response to disturbance or vegetation management. For 

example in the Intermountain West, the densest and most extensive stands of 

B. tectorum in unburned sagebrush occur in locations with hot dry summers 

and relatively warm, wet winters (Lavin and others, in review). These conditions minimize plant growth in mid-summer and promote plant growth in the 

winter and are characteristic of the Lahontan Basin (MLRA 27 & 24), Columbia 

Plateau (MLRA 8), lower Snake River Plain (western half of MLRA 11), and 

west central Utah (small central portion of MLRA 28A).

How to use this score sheet—Scores are based on soil temperature and 

moisture indicators, pre-fire plant composition, and estimated fire severity. 

Large wildfires frequently burn across several ecological sites or types. The % 

Area on the score sheet is the estimated proportion of the ecological site type 

within the treatment area. Explanations of the variables used in the score 

sheet are found in appendix 7b. If pre-wildfire vegetation is not known, see 

“Pre-Wildfire Composition and Structure Unknown” in the text. To estimate 

fire severity following a wildfire, see Appendix 4.
USDA Forest Service RMRS-GTR-338. 2015 63

†The plot should represent a plant community and fit within one ecological site. It can vary in size but should be small enough to 

easily observe vegetation composition and structure by standing at one point or walking a short distance (approximately 100 ft).

Score Sheet for Rating Resilience to Disturbance and Resistance to Invasive Annual Grasses

Ecological Site or Type Name: _______________________________________________

_________________________________________________________________________

%Area: ______________ UTMs: ___________________________________________ (Use ecological site descriptions or guidelines for the MLRA with field assessment to complete score sheet.)

PLOT SCORE†

(Sample two to five plots per 

ecological site depending on 

size and variability of area.)

SITE CHARACTERISTICS SCORE FOR VARIABLE 1 2 3 4 5

Temperature (Soil temperature regime + Species or subspecies of sagebrush)

Soil temperature regime

1 = hot-mesic, 2 = warm-mesic, 3 = cool-mesic, 

or cool-cryic (resilience is low but resistance is 

high), 4 = warm-frigid, 5 = cool-frigid, 6 = warmcryic

Species or subspecies of sagebrush 1 = Wyoming, low, black, or Lahontan; 2 = basin, 

Bonneville, or xeric; 3 = mountain

A. Temperature Score =

Moisture (Precipitation + Soil texture + Soil depth)

Precipitation in inches (in) 1 = <10, 2 = 10-12, 3 = 12-14, 4 = >14

Soil texture 1 = clay, sand, or silt; 2 = silty, sandy, or clay 

loams; 3 = loam

Soil depth in inches (in) 0 = very shallow (<10), 1 = shallow (10-20), 

3 = moderately deep to deep (>20)

B. Moisture Score =

Temperature Score (A) + Moisture Score (B)

Pre-Fire Vegetation (PFV) (Plant groups modified by soil depth)

Plant Groups:

Deep-rooted perennial grasses (DRPG)

(potentially dominant in shallow to 

deep soils >10 in)

Sandberg bluegrass (POSE)

(potentially dominant in very shallow 

soils <10 in)

Perennial forbs (PF)

Invasive annual grasses (IAG)

0 = DRPG and POSE scarce to severely depleted 

(DRPG <2-3/m2 and/or less than 5% foliar cover)

3 = DRPG on soils >10 in deep scarce, but POSE 

or PF are >50% foliar cover (resistance may be 

relatively high, but resilience is low)

6 = DRPG on soils >10 in deep depleted (2-

3/m2

or about 5-10% foliar cover), or co-dominant 

with IAG; or on soils <10 in deep, POSE and PF 

5-15% foliar cover and co-dominant with IAG

9 = DRPG and PF dominant on soils >10 in deep;

or POSE and PF dominant on soils <10 in deep.

Pre-Fire Vegetation (PFV) Adjusted for Fire Severity (Estimated)

C. Adjusted Pre-Fire Vegetation

(Estimate from fire severity indicators in 

Appendix 4.)

Low severity wildfire = PFV x 95%

Moderate severity wildfire = PFV x 80%

High severity wildfire = PFV x 20%

Total Resilience & Resistance Score=Temperature (A) + Moisture (B) + Adjusted PFV(C)

Resilience & Resistance Rating: Very low = <10, Low = 10-14, Moderate = 15-20, High = >20
64 USDA Forest Service RMRS-GTR-338. 2015

Appendix 7b: Explanation of Variables Used in the Resilience and 

Resistance Score Sheet

Explanation of Variables Used in the Score Sheet for Rating Resilience and Resistance

Site 

Characteristics Variable Explanation

Score

min max

Temperature (Soil temperature regime + Species or subspecies of sagebrush)

Soil temperature

regime

1 = hot-mesic

2 = warm-mesic

3 = cool-mesic

3 = cool-cryic

4 = warm-frigid

5 = cool-frigid

6 = warm-cryic

Estimated from soil survey data, ESDs, or from elevation 

within each MLRA (see Appendix 2). It is necessary to 

adjust for aspect and to consider if you are in the lower 

(warm) or upper (cool) part of the temperature regime.

1 6

Species or 

subspecies of 

sagebrush

1 = Wyoming, low, black,

and Lahontan

2 = basin, Bonneville, and 

xeric

3 = mountain

Sagebrush species and subspecies correspond to soil 

temperature/moisture regimes as well as soil depth and 

texture, and differ over elevation gradients, as described 

in ESDs, Table 3, and Appendix 2. Species identities are

confirmed through on-site surveys.

1 3

Temperature (A) Sum of soil temperature + sagebrush subspecies 2 9

Moisture (Precipitation + Soil texture + Soil depth)

Precipitation in 

inches (in)

1 = <10 in

2 = 10 to 12 in

3 = 12 to 14 in

4 = >14 in

Estimated from soil surveys, ESDs, or climate models, 

and confirmed on-site. Soil moisture regimes are: < 10 in 

= dry-aridic; 10 to 12 in = aridic; 12 to 14 in = xeric; >14 

in = moist-xeric.

1 4

Soil texture

1 = clay, sand, or silt

2 = silty, sandy, or clay loams

3 = loam

Dominant soil texture in upper 20 in of soil profile from 

soil descriptions and on-site soil pits. Loams often show 

balance between infiltration and water storage capacity; 

clay, sand, or silt soils are more variable.

1 3

Soil depth in 

inches (in)

0 = very shallow (<10)

1 = shallow (10 to 20)

3 = mod deep to deep (>20)

Depth to restrictive layer from soil descriptions and onsite soil pits. Soil depth largely determines water storage 

capacity and rooting depth.

0 3

Moisture (B) Sum of precipitation + soil texture + soil depth 2 10

Total Temperature (A) + Moisture (B) Sum of temperature and moisture scores 4 19

Pre-Fire Vegetation (PFV) (Plant groups modified by soil depth)

Plant Groups

Deep-rooted 

perennial grasses 

(DRPG)

Sandberg 

bluegrass (POSE)

Perennial Forbs 

(PF)

Invasive annual 

grasses (IAG)

0 = DRPG scarce to severely 

depleted (<2-3/m2); or POSE 

and PF are <5% foliar cover on 

very shallow soils

0 = DRPG are <2/m2 for xeric and <3/m2 for aridic; 

invasives are dominant or, if invasives are not dominant,

woody species (shrubs or trees) are near maximum

cover.

0 9

3 = Soils >10 in deep; DRPG 

scarce; but POSE, PF, and/or 

crusts >50% cover

3 = Cover of POSE, PF, and/or crusts is high. 

Establishment of DRPG is often limited, thus resilience 

may be low, but resistance can still be high. 

6 = Soils >10 in deep; DRPG 

depleted (2-3/m2, 5-10% cover); 

or where soils <10 in deep, 

POSE and PF 5-15% cover 

and/or co-dominant with IAG

6 = Abundance of DRPG, POSE, and PF is near or equal 

to IAG (IAG abundance is highly variable depending on 

moisture). IAG have low abundance (<5% cover), and 

DRPG are depleted, but >2/m2 for xeric and >3/m2 for 

aridic; or soils are very shallow and POSE and PF are 5 

to 15% cover.

9 = Soils >10 in deep and 

DRPG dominant; or soils <10 in 

deep and POSE or PF dominant

9 = Native grasses and forbs are dominant. If the area is 

seeded to non-native grasses, return to the reference state 

is unlikely, but resistance to annual grasses can be high.

Pre-Fire Vegetation (PFV) Adjusted for Fire Severity (Estimated)

PFV adjusted for 

fire severity 

based on 

indicators in 

Appendix 4.

Low severity fire = PFV x 95% Low severity fire can occur on low productivity sites and 

results in little mortality of perennial grasses and forbs.

Moderate severity fire = PFV x 0 8.6

80%

Moderate severity fire can occur in Phase I and II 

woodlands and high density shrublands.

High severity fire = PFV x 20% High severity fire usually occurs in Phase III woodlands.

Total Resilience and Resistance Score Rating: 

Very low = <10, Low = 10-14, Moderate = 15-20,

High = >20

Temperature (A) + Moisture (B) + Adjusted PFV(C) = 

Resilience & Resistance Score 4 27.6
USDA Forest Service RMRS-GTR-338. 2015 65

Appendix 7c. Example of Rating Resilience and Resistance to 

Invasive Annual Grasses

Example of rating resilience and resistance to invasive annual grasses for the 

mesic/aridic Wyoming big sagebrush (8 to 12 inch PZ) ecological type, where 

the pre-treatment vegetation varies in ecological condition and fuel characteristics. See the STM for this ecological type in Appendix 5A to determine the 

potential states and community phases. 
66 USDA Forest Service RMRS-GTR-338. 2015

†The plot should represent a plant community and fit within one ecological site. It can vary in size but should be small enough to 

easily observe vegetation composition and structure by standing at one point or walking a short distance (approximately 100 ft).

Score Sheet for Rating Resilience to Disturbance and Resistance to Invasive Annual Grasses

Ecological Site or Type Name: Mesic/aridic Wyoming big sagebrush/Thurber needlegrass 

(8 to 12 inch PZ)_______________________________

%Area: _60%___________ UTMs: _(your site) ________________________________ (Use ecological site descriptions or guidelines for the MLRA with field assessment to complete score sheet.)

PLOT SCORE†

(Sample two to five plots per 

ecological site depending on 

size and variability of area.)

SITE CHARACTERISTICS SCORE FOR VARIABLE 1 2 3 4 5

Temperature (Soil temperature regime + Species or subspecies of sagebrush)

Soil temperature regime

1 = hot-mesic, 2 = warm-mesic, 3 = cool-mesic, 

or cool-cryic (resilience is low but resistance is 

high), 4 = warm-frigid, 5 = cool-frigid, 6 =

warm-cryic

2 3 2 2 3

Species or subspecies of sagebrush 1 = Wyoming, low, black, or Lahontan;

2 = basin, Bonneville, or xeric; 3 = mountain 1 1 1 1 1

A. Temperature Score = 3 4 3 3 4

Moisture (Precipitation + Soil texture + Soil depth)

Precipitation in inches (in) 1 = <10, 2 = -12, 3 = 12-14, 4 = >14 2 2 2 2 2

Soil texture 1 = clay, sand, or silt; 2 = silty, sandy, or clay 

loams; 3 = loam 2 2 2 2 2

Soil depth in inches (in) 0 = very shallow (<10), 1 = shallow (10-20), 

3 = moderately deep to deep (>20) 3 3 3 3 3

B. Moisture Score = 7 7 7 7 7

Temperature Score (A)+ Moisture Score (B) 10 11 10 10 11

Pre-Fire Vegetation (PFV) (Plant groups modified by soil depth)

Plant Groups:

Deep-rooted perennial grasses (DRPG)

(potentially dominant in shallow to 

deep soils >10 in)

Sandberg bluegrass (POSE)

(potentially dominant in very shallow 

soils <10 in)

Perennial forbs (PF)

Invasive annual grasses (IAG)

0 = DRPG and POSE scarce to severely depleted 

(DRPG <2-3/m2 and/or less than 5% foliar cover)

3 = DRPG on soils >10 in deep scarce, but POSE 

or PF are >50% foliar cover (resistance may be 

relatively high but resilience is low)

6 = DRPG on soils >10 in deep depleted (2-

3/m2

or about 5-10% foliar cover), or co-dominant 

with IAG; or on soils <10 in deep POSE and PF 

5-15% foliar cover and co-dominant with IAG

9 = DRPG and PF dominant on soils >10 in deep;

or POSE and PF dominant on soils <10 in deep.

0

3

0

3

6

Pre-Fire Vegetation (PFV) Adjusted for Fire Severity (Estimated)

C. Adjusted Pre-Fire Vegetation

(Estimate from fire severity indicators in 

Appendix 4.)

Low severity wildfire = PFV x 95%

Moderate severity wildfire = PFV x 80%

High severity wildfire = PFV x 20%

0

2.9

0

2.9

4.8

Total Resilience & Resistance Score=Temperature (A) + Moisture (B) + Adjusted PFV(C) 10 14 10 13 16

Resilience & Resistance Rating: Very low = <10, Low = 10-14, Moderate = 15-20, High = >20
USDA Forest Service RMRS-GTR-338. 2015 67

Potential vegetation on this ecological site is Wyoming big sagebrush and 

Thurber needlegrass. Soil temperatures vary from warm-mesic to cool-mesic 

depending on elevation and aspect. Mean annual precipitation is 10 to 12 

inches. Soils are moderately deep clay loams. Current vegetation ranges 

from severely depleted on approximately 65% of the area to native perennial 

grasses and forbs dominating the understory on about 15% of the area. Fire 

severity varies from low to moderate. Resilience on the majority of the area 

(75%) is very low to low. The only area where resilience is moderate to approaching high is where native perennial herbaceous vegetation is dominant.

Explanation of Resilience and Resistance 

Rating from Example Score Sheet.
68 USDA Forest Service RMRS-GTR-338. 2015

Appendix 8: Definitions of Terms Used in This Field Guide 

(For soil terms, see Appendix 3) 

At-risk phase—A community phase that is most vulnerable to transition to an alternative state 

(for example, least resilient). See Phase.

Ecological site—A conceptual division of the landscape that is defined as a distinctive kind of 

land based on recurring soil, landform, geological, and climate characteristics; that differs 

from other kinds of land in its ability to produce distinctive kinds and amounts of vegetation and in its ability to respond similarly to management actions and natural disturbances. 

Similar to “ecological type” used by the USDA Forest Service and “Range Site Description” 

used by the NRCS.

Ecological Site Descriptions (ESD) —The documentation of the characteristics of an ecological 

site. The documentation includes data used to define the distinctive properties and characteristics of the ecological site; the biotic and abiotic characteristics that differentiate the site 

(i.e., climate, topography, soil characteristics, and plant communities); and the ecological 

dynamics of the site that describe how changes in disturbance processes and management 

can affect the site. An ESD also provides interpretations about the land uses and ecosystem 

services that a particular ecological site can support and management alternatives for 

achieving land management. Similar to “ecological type” used by the USDA Forest Service 

and “Range Site Description” used by the NRCS.

Ecological type—A category of land with a distinctive combination of landscape elements—

specifically, climate, geology, geomorphology, soils, and potential natural vegetation. 

Ecological types differ from one other in their ability to produce vegetation and respond to 

management and natural disturbances. 

Fire intensity—A general term relating to the heat energy released in a fire; the amount and 

rate of surface fuel consumption.

Fire severity—The effects of fire on ecological processes, soil, flora, and fauna; the degree to 

which a site has been altered or disrupted by fire.

Major Land Resource Areas/MLRAs—Geographic area that is usually several thousand acres in 

extent and characterized by a particular pattern of soils, climate, water resources, and land 

use.

Phase (community) —Community phases interact with the environment to produce a characteristic composition of plant species, functional and structural groups, soil functions, and 

range of variability. Phases may not progress directly to the most resilient community phase 

without passing through an intermediate phase. 

Potential vegetation—As described in an ESD, is a function of ecological site characteristics 

(climate, topography, and soils), attributes and processes (soil temperature/moisture regime, soil processes, and vegetation dynamics), and disturbance history.
USDA Forest Service RMRS-GTR-338. 2015 69

Reference state—Historical or potential plant community, including seral (successional) 

stages; based on conditions believed to be present before widespread alterations by 

Euro-Americans.

Resilience—Capacity of an ecosystem to regain its fundamental structure, processes, and functioning when altered by stresses such as increased CO2, nitrogen deposition, and drought 

and by disturbances such as land development and fire.

Resistance—Capacity of an ecosystem to retain its fundamental structure, processes, and functioning (or remain largely unchanged) despite stresses, disturbances, or invasive species.

Resistance to invasion—Abiotic and biotic attributes and ecological processes of an ecosystem 

that limit the population growth of an invading species.

Restoration pathways—These describe the environmental conditions and management practices that are required to recover a state that has undergone a transition. 

State—A suite of plant community successional phases occurring on similar soils that interact 

with the environment to produce resistant functional and structural attributes with a characteristic range of variability that are maintained through autogenic repair mechanisms.

Treatment area—An area that is being considered for some form of vegetation manipulation 

(prescribed fire or mechanical treatments) to increase resilience and/or resistance or that 

has experienced a wildfire. The treatment area is often composed of different ecological 

sites that may have different resilience to disturbance and resistance to invasives (a result 

of varying elevation, topography, soils, and disturbance history). It is helpful to place these 

sites into general groups based on soil moisture/temperature regime and current vegetation.

Woodland phase I, II, III—Phase I trees are present but shrubs and herbs are the dominant 

vegetation influencing ecological processes on the site; phase II trees are co-dominant with 

shrubs and herbs, and all three vegetation layers influence ecological processes; phase III

trees are the dominant vegetation on the site and the primary plant layer influencing ecological processes on the site (from Miller and others 2005). Phases can be calculated using % 

cover (from Roundy and others 2014).

Phase I = total tree / total tree + shrub + perennial grass = <0.33 (tree biomass <1/3)

Phase II = total tree / total tree + shrub + perennial grass = 0.34 to 0.65 (tree biomass 1/3 to 2/3)

Phase III = total tree / total tree + shrub + perennial grass = >0.66 (tree biomass >2/3)
70 USDA Forest Service RMRS-GTR-338. 2015

Phases of Woodland Succession

Characteristics

(post-settlement stands)

Phase I

(early)

Phase II

(mid)

Phase III

(late)

Tree canopy

percentage of maximum 

potential cover

Open, actively 

expanding

<1/3 max potential 

Open, actively expanding

1/3 to 2/3 max potential

Expansion nearly 

stabilized

>2/3 max potential

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%

Tree recruitment Active Active Limited to absent

Potential berry production Low Moderate to high Low to near absent

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

*Crown lift is the mortality of lower tree limbs usually associated with shading of neighboring trees as tree 

density and size increases in relatively dense stands.
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at any USDA office or write a letter addressed to USDA and provide in the letter all of the information requested in the form. To request a copy of the complaint form, call (866) 632-9992. 

Submit your completed form or letter to USDA by: (1) mail: U.S. Department of Agriculture, Office of the Assistant Secretary for Civil Rights, 1400 Independence Avenue, SW, Washington, 

D.C. 20250-9410; (2) fax: (202) 690-7442; or (3) email: program.intake@usda.gov. 

United States Department of Agriculture

Forest Service

Rocky Mountain Research Station