United States

Department of

Agriculture

Forest Service

Pacific Northwest

Research Station

United States

Department of

the Interior

Bureau of Land

Management

General Technical

Report

PNW-GTR-553

September 2002

Altered Rangeland Ecosystems

in the Interior Columbia Basin

Stephen C. Bunting, James L. Kingery, Miles A. Hemstrom,

Michael A. Schroeder, Rebecca A. Gravenmier, and

Wendel J. Hann
Authors

Stephen C. Bunting is a professor and James L. Kingery is an associate professor,

Department of Rangeland Ecology and Management, University of Idaho, Moscow, ID

83844-1135; Miles A. Hemstrom is a research ecologist and Rebecca A. Gravenmier

is a natural resource specialist, U.S. Department of Agriculture, Forest Service, Pacific

Northwest Research Station, P.O. Box 3890, Portland, OR 97208; Michael A. Schroeder

is a wildlife ecologist, Washington Department of Fish and Wildlife, Bridgeport, WA 98813;

and Wendel J. Hann is a landscape fire ecologist, U.S. Department of Agriculture, Forest

Service, Fire Management, 50 Highway 93 South, Salmon, ID 83467.
Altered Rangeland Ecosystems in the

Interior Columbia Basin

Stephen C. Bunting, James L. Kingery, Miles A. Hemstrom,

Michael A. Schroeder, Rebecca A. Gravenmier, and

Wendel J. Hann

Interior Columbia Basin Ecosystem Management Project:

Scientific Assessment

Thomas M. Quigley, Editor

U.S. Department of Agriculture

Forest Service

Pacific Northwest Research Station

Portland, Oregon

General Technical Report PNW-GTR-553

September 2002
United States

Department of

Agriculture

Forest Service

United States

Department of

the Interior

Bureau of Land

Management

Interior

Columbia

Basin

Ecosystem

Management

Project

Executive Summary

A workshop was held to address specific questions related to altered rangeland ecosystems within the Interior Columbia basin (hereafter referred to as the basin). Focus

was primarily on lands administered by the Forest Service (FS) and Bureau of Land

Management (BLM). Altered ecosystems were considered to be those where humaninduced or natural disturbances are of sufficient magnitude to change ecosystem processes. Long-term loss or displacement of native community types and reduction of

productive potential makes it difficult or impossible to restore these ecosystems to historical conditions. Seventeen rangeland potential vegetation types (PVTs) that are found

within the basin are briefly described. Descriptions of riparian or woodland vegetation

are not included.

The major factors that have altered the 17 rangeland PVTs are discussed. The most

common factors that have affected the PVTs found in the basin include livestock grazing, invasive species, and changes in fire regime. Climatic change has probably been an

important factor, but it is difficult to identify the specific influences. Agricultural development has been an important factor on private lands, and in some cases, these influences

have spread to adjacent BLM- and FS-managed lands.

Six rangeland PVTs were identified as the most seriously affected in the basin. Selection of these PVTs was related to the degree of alteration, areal extent of the PVT, and

the overall importance to the basin as a whole. These include salt desert shrub, Wyoming big sagebrush–warm, basin big sagebrush, mountain big sagebrush–mesic west,

mountain big sagebrush–mesic west with juniper, and wheatgrass grassland.

Many altered ecosystems may be restorable, but success of these efforts is variable

and untested for many restoration methods. Options exist to restore some altered rangeland ecosystems by restoring native plant communities, stabilizing ecosystem processes,

reducing the spread of invasive species, or conserving existing biota. In some altered

conditions, these options have a relatively high probability of success over the short

term with low to moderate cost at the site scale. However, in other altered conditions,

restoration options are expensive, have a low probability of success, and require long

timeframes. Failure to restore the most severely altered PVTs will affect the future

stability of these areas.
The PVTs differed considerably in the extent to which vegetation composition had

changed. The feasibility of restoration of the six most severely altered PVTs in the basin

was discussed by the workshop participants from four perspectives. The overall feasibility of restoration of the mountain big sagebrush–mesic west was high. Restoration could

primarily be accomplished through changes in the management of fire and livestock

grazing. Potential recruitment of native species was high where seed sources were

present and alteration by invasive species was low. These management changes could

be enacted relatively inexpensively, and the vegetation would respond rapidly to the

changes. Restoration of salt desert shrub and wheatgrass grassland PVTs was thought

to be the least feasible. Restoration of these PVTs would in most cases require control

of invasive species and seeding of native species. In addition, soil and topographic features limit many types of restoration practices. Recruitment rates of native species

are low owing to severe environmental conditions such as low rainfall. Consequently,

restoration would require a long time. Altered portions of the salt desert shrub are often

dominated by annual grasses that greatly increase wildfire occurrence. Wildfires would

need to be suppressed for many years to enable recruitment of the native shrubs in

this PVT.

Restoration of those sites within the mountain big sagebrush–mesic west with juniper in

the early stages of woodland development was highly feasible. The response would be

similar to that of the mountain big sagebrush–mesic west. However, restoration of those

sites that had advanced through succession to later woodland stages was less feasible.

Juniper may have to be removed by using methods other than fire, such as cutting or

other mechanical means. In many cases shrub and herbaceous species have been severely reduced on these sites. Shrubs and native perennial grasses have been successfully established through seeding, but little is known about the establishment of many of

the native forbs associated with this PVT.

Altered sites in the Wyoming big sagebrush–warm and basin big sagebrush PVTs have

a moderate restoration feasibility because of the presence of invasive species and subsequent reduction of recruitment of species native to these PVTs. Many areas are also

subject to frequent wildfire that prevents sagebrush recruitment. Severely altered sites

require seeding of native species. Availability of seed sources is limited, and the establishment requirements for seedlings for many of these species is not well understood.

Greater sage grouse (Centrocercus urophasianus) and Columbian sharp-tailed grouse

(Tympanuchus phasianellus) are extremely important species within the basin because

of their widespread historical distribution, declining status, and potential use of most of

the PVTs. Sage grouse densities vary by season and PVT because of seasonal movements and their dependence on sagebrush leaves during winter, shrub and herbaceous

cover during spring, and forbs during summer. This natural variation has been exacerbated by differences in quantity, quality, and configuration of the PVTs. Of the six PVTs

evaluated by workshop participants, only Wyoming big sagebrush–warm, basin big sagebrush, mountain big sagebrush–mesic west, and mountain big sagebrush–mesic west

with juniper were considered to be primary habitats for greater sage grouse. The mountain big sagebrush PVTs were believed to be relatively intact, thus offering the best

opportunities for restoration. Unfortunately, these PVTs tend to be at relatively high

elevations and somewhat isolated by vast areas of alternate habitats less suitable for

sage grouse. The Wyoming and basin big sagebrush PVTs were believed to offer the
greatest restoration challenge because of their dramatically altered characteristics.

Nevertheless, their restoration may be the best way to realistically ensure the viability

of greater sage grouse in the region, because of their immense size and the connections

they provide between the smaller and more isolated PVTs. It is clear from this workshop that habitat management and restoration for greater sage grouse will require planning and action over a vast landscape.

Similar to densities of greater sage grouse, densities of Columbian sharp-tailed grouse

also vary by season and PVT. Sharp-tailed grouse tend to depend on herbaceous cover

during spring, forbs during summer, and deciduous shrubs and trees during winter. Of

the six PVTs evaluated by workshop participants, only mountain big sagebrush–mesic

west, mountain big sagebrush–mesic west with juniper, and wheatgrass grassland are

likely to be primary habitats for sharp-tailed grouse. Although other PVTs also can be

used by sharp-tailed grouse, their usage is often dependent on their proximity to a primary PVT. The mountain big sagebrush PVTs seem to be relatively intact, thus offering

excellent opportunities for restoration. In contrast, the wheatgrass grassland has largely

been eliminated by conversion to cropland. Among all 17 PVTs in the basin, the relatively high-elevation PVTs appear to be the most important for sharp-tailed grouse.

These include Wyoming big sagebrush–cool, threetip sagebrush, mountain big sagebrush

(four types), wheatgrass grassland, mountain shrub, and fescue grassland (two types).

Because many of these habitats are small, isolated, and long distances from existing

populations of sharp-tailed grouse, it is likely that restoration should be focused in specific areas where there are opportunities to expand or connect existing populations. As

with greater sage grouse, management and restoration of Columbian sharp-tailed grouse

will require planning and action over a vast landscape.
Abstract

Bunting, Stephen C.; Kingery, James L.; Hemstrom, Miles A.; Schroeder, Michael A.;

Gravenmier, Rebecca A.; Hann, Wendel J. 2002. Altered rangeland ecosystems in the

interior Columbia basin. Gen. Tech. Rep. PNW-GTR-553. Portland, OR: U.S. Department

of Agriculture, Forest Service, Pacific Northwest Research Station. 71 p. (Quigley, Thomas M.,

ed.; Interior Columbia Basin Ecosystem Management Project: scientific assessment).

A workshop was held to address specific questions related to altered rangeland ecosystems within

the interior Columbia basin. Focus was primarily on public lands administered by the Forest Service

and Bureau of Land Management. Altered ecosystems were considered to be those where humaninduced or natural disturbances are of sufficient magnitude to affect ecosystem processes, causing

long-term loss or displacement of native community types and loss of productivity, making it difficult

or impossible to restore these ecosystems to historical conditions. Seventeen rangeland potential vegetation types (PVT) were identified by the Interior Columbia Basin Ecosystem Management Project

and briefly described. Reasons that rangeland ecosystems are altered include presence of invasive

species, uncharacteristic grazing effects, climatic change, change in fire regime, and other factors

related to human presence. However, primary causes of alteration and restoration potential differ

among PVTs. Some altered rangeland ecosystems may be restored by stabilizing ecosystem processes, restoring native plant communities, reducing the spread of invasive species, or conserving

existing biota. In some altered conditions, these options have a relatively high probability of success

over the short term with low to moderate cost at the site scale. However, in other altered areas,

restoration options are expensive, have a low probability of success, and require long timeframes.

Restoration of rangeland PVTs is also necessary for the survival of some animal species whose

populations are in decline such as the Columbian sharp-tailed grouse and greater sage grouse.

Keywords: Altered rangelands, Columbia sharp-tailed grouse, greater sage grouse, restoration,

potential vegetation types, rangeland ecosystems.
Contents

 1 Introduction

 1 Methods

 4 Questions Addressed

 4 Rangeland PVTs Found Within the Basin

12 Salt Desert Shrub PVT

14 Wyoming Big Sagebrush–Warm PVT

20 Wyoming Big Sagebrush–Cool PVT

21 Basin Big Sagebrush PVT

22 Threetip Sagebrush PVT

22 Low Sagebrush–Xeric PVT

23 Low Sagebrush–Mesic PVT

25 Low Sagebrush–Mesic with Juniper PVT

26 Mountain Big Sagebrush–Mesic East PVT

26 Mountain Big Sagebrush–Mesic East with Conifers PVT

27 Mountain Big Sagebrush–Mesic West PVT

28 Mountain Big Sagebrush–Mesic West with Juniper PVT

29 Wheatgrass Grassland PVT

31 Antelope Bitterbrush PVT

32 Mountain Shrub PVT

32 Fescue Grassland PVT

33 Fescue Grassland with Conifer PVT

33 Primary Causes of PVT Alteration

36 Management Options and Feasibility for Restoration

38 Salt Desert Shrub PVT

39 Wyoming Big Sagebrush–Warm PVT

41 Basin Big Sagebrush PVT

41 Mountain Big Sagebrush–Mesic West PVT

43 Mountain Big Sagebrush–Mesic West with Juniper PVT

44 Wheatgrass Grassland PVT

45 Potential for Increasing Greater Sage Grouse Populations

48 Potential for Increasing Columbian Sharp-Tailed Grouse Populations

49 Conclusion

51 Acknowledgments

52 English Equivalents

52 Literature Cited

68 Appendix 1

69 Appendix 2
1

Introduction

The interior Columbia basin (hereafter referred

to as the basin) is a diverse region including that

portion of the Columbia River drainage within the

United States between the crest of the Cascade

Range on the west to the Continental Divide on

the east (fig. 1). In addition, it includes a portion

of the Klamath River basin and the Great Basin to

the south. It encompasses 58.4 million ha nearly

53 percent of which is managed by the USDA

Forest Service (FS) and USDI Bureau of Land

Management (BLM) (Quigley and Arbelbide

1997). A recent landscape assessment of the

basin provided detailed information on the broadscale current conditions and trends within the

basin (Hann et al. 1997). The assessment found

that numerous factors had altered many ecological components and processes. The most intensive alteration, agricultural development, had

affected 17 percent of the area. Other factors

that were less intensive but more extensive had

affected large portions of the basin. Fire regimes

had been altered, resulting in greater fire severity

and decreased fire frequency. Invasive species

had altered ecosystem characteristics across

nearly 47 percent of the basin. Improper livestock

grazing had affected much of the rangeland and

dry forest vegetation types. Improper grazing is

defined as the degree of use of the current year’s

growth that results in the reduction of the longterm productivity of the site and failure of the site

to meet the land management objectives. Improper use may result from one or a combination of

factors including season of grazing use, duration

of use, or numbers of animals. Hemstrom et al.

(in press) and Wisdom et al. (in press) examined

the conditions and likely future trends of rangelands and associated species in the basin, concluding that further deterioration is likely in the future.

The landscape assessment and rangeland projections were the impetus for a workshop to specifically address altered rangelands within the basin.

Methods

The following is a summary of a collaborative

survey of vegetation and vertebrate ecologists

concerning altered rangeland communities within

the basin. Conducted during a 3-day workshop

held August 28–30, 2000, the survey represents

the collective assessment of those attending the

workshop. The workshop was attended by 31

individuals affiliated with federal, state, and private organizations from throughout the basin

(app. 1). These people represented various disciplines related to plant and animal ecology. They

had expertise in both research and land management on the various ecosystems found within

the basin. The need for a survey and workshop

originated from concerns on projected environmental consequences for rangelands and associated animal species considered in the Interior

Columbia Basin Ecosystem Management Project

(ICBEMP) Supplemental Draft Environmental

Impact Statement (SDEIS). The primary focus

was conditions of rangelands administered by

the FS and BLM.

Information on historical and current rangeland vegetation was based on prior modeling

by Hemstrom et al. (in press) and Hann et al.

(1997). The foundation for this modeling was the

vegetation information developed by Hann et al.

(1997) that described 17 rangeland potential

vegetation types (PVTs) in the basin and more

than 50 cover type-structural stage combinations

that are nested within these PVTs. A “potential

vegetation type” (PVT) is defined as the representation of the biophysical properties of a portion of land that is described by the successional

Figure 1—Interior Columbia Basin Ecosystem Management

Project area.

Interior Columbia 

Basin Ecosystem 

Management 

Project area

State boundaries
2

convergence to a homogenous vegetation community. The concept is similar to that of a “potential natural community” (Jacoby 1989), except

that the classification is at a coarser scale.

Coarse-scale PVTs are usually a group of similar

habitat types or plant associations (Keane et al.

1996). Potential vegetation types reflect biophysical conditions, disturbance regimes, and the suite

of plant communities that can occupy sites over

time (Hann et al. 1997). Menakis et al. (1996)

describe the methods used in the development of

the PVTs. Wisdom et al. (2000) provide a summary of the estimation methods and associated

accuracy of the classification system. Vegetation

cover and structure are transient and reflect the

vegetation present at any given time. Cover types

reflect the dominant species in upper canopy

layers, whereas structural stages depict the horizontal and vertical arrangement of vegetative

structures (e.g., canopy cover/height class) and

are related to temporal vegetation development

patterns (Hann et al. 1997). The base vegetation

data included 41 cover types and 25 structural

stages across the basin mapped at a resolution

of 1-km2 pixels (fig. 2) (Hann et al. 1997, Wisdom

et al. 2000).

The reference point for change was the historical range of conditions resulting from 100-

and 400-year simulations of conditions prior to

Euro-American settlement. Hann et al. (1997)

described simulations of the historical range of

conditions and summarized late 1800s mapped

conditions that were used as baseline. They assumed climatic conditions similar to those that

exist at present. In this sense, their historical

conditions could be considered expected conditions under current climate given disturbance

regimes similar to those that preceded EuroAmerican settlement. Climatic conditions have

not been stable over the last few hundred years

(e.g., Tausch and Nowak 2000) and it is difficult

to separate the influences of climate change

from influences of land use and related changes

in disturbances. However, we use the modeled

range of variability from Hann et al. (1997)

as a baseline from which to estimate those

Figure 2—Upper Salmon River Valley north of Stanley, Idaho, consisting of a mosaic of mountain big sagebrush–

mesic east, riparian, and conifer PVTs. The riparian vegetation in the center will not be indicated on a vegetation

map at the 1-km scale, and the area will be classified into a “dominant” PVT. (Photo by Stephen Bunting.)
3

vegetation conditions that may have been altered

by excessive livestock grazing and related factors. It is likely that some of the altered conditions

we discuss include complex interactions between

human uses and climatic change. In addition,

future conditions may not be represented in either

the simulated historical conditions or the present

conditions. More work is needed to determine

changes that could be addressed through management versus those occurring because of

broader scale climate change.

Current vegetation maps were developed to reflect average conditions from 1985 to 1995, relying on a combination of satellite imagery, aerial

photography, sample data, and a map of landcover characteristics (Hann et al. 1997, Hessburg

et al. 1999, Keane et al. 1996, Menakis et al.

1996). Each pixel was assigned one cover type

and structural stage that reflected the likely dominant condition. Although each pixel is actually

a mosaic of conditions at finer resolutions, the

data were insufficient to refine resolution beyond

1 km. Estimates of conditions from these data,

while perhaps necessary at the scale of the entire

basin, are inherently limited by resolution and

other factors. Wisdom et al. (2000) cite several

limitations of particular relevance:

1. High variation in number of cover types

within the cell. Mapping units composed of

1-km2 cells typically contain three to five

different cover types that occur in patch

sizes of about 4 ha or larger. Typically, the

cover type with the largest area or greatest

biomass dominates the characteristics of

the cell. In many cases, the named type

only covers 20 to 30 percent of the cell

area, but it has the largest area and thus

dominates the reflectance shown in the

remote-sensed data source.

2. High variation in cover type distribution

within cells. Cover types that typically occur in small patches but are distributed

abundantly and scattered throughout the

cell also may dominate the characteristics

of the cell. Accurate mapping of these

types is dependent on summary of many

cells or grouping of cover types, which

again dampens the effect of high variation

in type distribution within cells.

3. Small sample size. Cover types that occur

in large patches, but that do not occur in

many cells, will dominate the characteristics of those cells. Accurate mapping of

these types is dependent on grouping of

related types, which dampens the effect

of small sample size.

4. Cover types with similar characteristics.

Two or more cover types that have similar

characteristics may dominate the characteristics of many cells. Accurate mapping

of these types is dependent on finding accurate correlations with other mapped biophysical and human-caused characteristics.

This dampens effects of errors in misclassification to other cover types that have

similar prediction characteristics.

The area of each PVT on BLM- and FS-administered lands within the SDEIS planning area was

classified into elevation and precipitation categories. Elevation was determined from a 500-m

digital elevation model (DEM). Elevation categories were defined as less than 1,000, 1,000 to

2,000, and greater than 2,000 m for the low, moderate, and high classes, respectively. The precipitation categories were defined as less than 30, 30

to 61, and greater than 61 cm for the low, moderate, and high classes, respectively.

Excessive livestock grazing, as we use the term,

is related to the degree to which grazing pressure

by livestock exceeds that of native ungulates

prior to Euro-American settlement. Our usage

is similar to “uncharacteristic grazing” as described by Hemstrom et al. (2001). Hemstrom

et al. (2001) estimated current excessive grazing

levels through a combination of livestock grazing

levels (data from FS and BLM field units), current potential vegetation types, cover types, and

structural stages. They assumed excessive grazing in rangeland PVTs was indicated by very

early seral condition or substantial presence or

dominance by exotic plant species. Although ungulate grazing did occur historically, the vegetation of the study area was not generally adapted
4

to high grazing pressure, particularly pressure

from bulk-grazers such as cattle (Mack and

Thompson 1982, Miller et al. 1994).

Questions Addressed

Workshop participants considered four primary

questions related to the alteration and restoration

of rangelands in the basin. They discussed each

question, after which a majority opinion was developed. To the extent possible, the information

presented here represents the majority opinion.

Question 1—What are the most likely causes

for altered rangeland ecosystems?

For the workshop, altered ecosystems were defined as areas that have been disturbed to the

extent that ecosystem processes have changed

or that long-term loss or displacement of native

community types and components has occurred.

Decline of productive potential may have occurred as well, making restoration to predisturbance conditions through natural processes alone

difficult. Altered ecosystem processes include

permanent changes in succession rates, creation

of new disturbance pathways, changes in species

composition, and permanent decline of productive

potential. Unfortunately, alteration includes

changes owing to both climate and land management. This question focused on changes owing

to land management, recognizing that climate

change was responsible for some portion of

altered conditions as well.

Question 2—Which specific rangeland potential

vegetation types are altered to the extent that

restoration to their historical or natural conditions

is unlikely?

To address this question, participants considered

all rangeland PVTs found within the basin and

identified those that were most altered and would

be difficult or perhaps impossible to restore to

prior natural conditions. For example, some PVTs

may be so altered owing to the introduction of

invasive species that they cannot be restored.

Question 3—What management options exist to

restore native communities within each potential

vegetation community, to stabilize conditions, or

to prevent alteration?

The following points were considered: (1) Which

restoration category (restore, stabilize, or prevent

alteration) is applicable? (2) Is restoration feasible? (3) Is the relative cost of restoration high,

moderate, or low? (4) Will restoration require

relatively little time (< 10 years), moderate

amounts of time (11 to 49 years), or long-term

efforts (> 50 years)? and (5) Is the likelihood of

success for restoration efforts relatively low,

moderate, or high?

Question 4—If the objective is to improve conditions for greater sage grouse (Centrocercus

urophasianus) or Columbian sharp-tailed grouse

(Tympanuchus phasianellus), what options can

be considered for prioritizing areas for conservation and restoration? What conservation and restoration techniques can be used for key habitats

and what are their values?

Responses to the above questions differed considerably depending on specific environments

within the selected PVTs. It was agreed that

most environments require active restoration,

passive restoration, or both. Consequently, the

focus of the discussions was on restoration

opportunities, rather than identifying where

restoration was not possible.

Rangeland PVTs Found

Within the Basin

Seventeen dry grass, dry shrub, and cool shrub

PVTs were identified in the basin (Hann et al.

1997, Keane et al. 1996). Menakis et al. (1996)

described the process of PVT classification.

The PVT descriptions were developed from

many sources but particularly from the vegetation

classification research of Daubenmire (1970),

Hironaka et al. (1983), Johnson (1987), Mueggler

and Stewart (1980), Tisdale (1986), Zamora and

Tueller (1973) and the work of Knight (1994)

(table 1). Workshop participants identified factors

related to the importance of each PVT within the

basin. Environmental characteristics (table 2) and

past land use activities were identified for each
5

PVT that increased its likelihood of becoming

altered. Riparian, woodland, and forest PVTs

were not considered in this evaluation. Several

rangeland PVTs include the possibility for conifer

encroachment, particularly following reduction of

fire frequency. We include these in rangelands

because they were historically dominated by

rangeland vegetation rather than conifers. In addition, these PVTs are generally labeled by their

dominant rangeland condition under historical

Table 1—Relations between rangeland potential vegetation types found within the interior

Columbia basin and previously published habitat type classificationsa

Potential vegetation type (PVT) Prior habitat type classificationsb

Salt desert shrub Daubenmire (1970) eastern Washington

Sarcobatus vermiculatus/Distichlis stricta

Grayia spinosa/Poa secunda

Eurotia lanata/Poa secunda

Mueggler and Stewart (1980) western Montana

Sarcobatus vermiculatus/Agropyron smithii

Sarcobatus vermiculatus/Elymus cinereus

Note: Salt desert shrub habitat types have not been adequately

described for most of the basin.

Wyoming big sagebrush–warm Daubenmire (1970) eastern Washington

Artemisia tridentata/Agropyron spicatum

Hironaka et al. (1983) southern Idaho

Artemisia tridentata subsp. wyomingensis/Poa sandbergii

Artemisia tridentata subsp. wyomingensis/Sitanion hystrix

Artemisia tridentata subsp. wyomingensis/Stipa thurberiana

Artemisia tridentata subsp. wyomingensis/Agropyron spicatum

Artemisia tridentata subsp. wyomingensis/Stipa comata

Artemisia tridentata subsp. xericensis/Agropyron spicatum

Artemisia tridentata subsp. xericensis/Festuca idahoensis

Wyoming big sagebrush–cool Daubenmire (1970) eastern Washington

Artemisia tridentata/Festuca idahoensis

Mueggler and Stewart (1980) western Montana

Artemisia tridentata /Agropyron spicatum

Hironaka et al. (1983) southern Idaho

Artemisia tridentata subsp. wyomingensis/Poa sandbergii

Artemisia tridentata subsp. wyomingensis/Sitanion hystrix

Artemisia tridentata subsp. wyomingensis/Stipa thurberiana

Artemisia tridentata subsp. wyomingensis/Agropyron spicatum

disturbance regimes rather than their tendency

for conifer encroachment under current disturbance regimes. The following section provides a

general description of the characteristic vegetal

and environmental conditions for the 17 rangeland

PVTs found within the basin. General management and restoration discussions are provided for

11 PVTs that are not discussed in detail in the

“management options and feasibility of restoration” section of this manuscript.
6

Table 1—Relations between rangeland potential vegetation types found within the interior

Columbia basin and previously published habitat type classificationsa (continued)

Potential vegetation type (PVT) Prior habitat type classificationsb

Basin big sagebrush Daubenmire (1970) eastern Washington

Artemisia tridentata/Agropyron spicatum

Hironaka et al. (1983) southern Idaho

Artemisia tridentata subsp.tridentata/Agropyron spicatum

Artemisia tridentata subsp.tridentata/Stipa comata

Threetip sagebrush Daubenmire (1970) eastern Washington

Artemisia tripartita/Agropyron spicatum

Artemisia tripartita/Festuca idahoensis

Mueggler and Stewart (1980) western Montana

Artemisia tripartita/Festuca idahoensis

Hironaka et al. (1983) southern Idaho

Artemisia tripartita/Agropyron spicatum

Artemisia tripartita/Festuca idahoensis

Low sagebrush–xeric Daubenmire (1970) eastern Washington

Eurotia lanata/Poa secunda

Yensen and Smith (1984) southwestern Idaho

Ceratoides lanata/Artemisia tridentata subsp. wyomingensis

Atriplex falcata/Artemisia tridentata subsp. wyomingensis

Note: Winterfat and other salt desert shrub habitat types have

not been adequately described for most of the basin.

Low sagebrush–mesic Daubenmire (1970) eastern Washington

Artemisia rigida/Poa secunda

Zamora and Tueller (1973) northern Nevada

Artemisia arbuscula/Stipa thurberiana

Artemisia arbuscula-Purshia tridentata/Agropyron spicatum

Artemisia arbuscula/Festuca idahoensis

Artemisia longiloba/Festuca idahoensis

Artemisia nova/Agropyron spicatum

Artemisia nova/Agropyron inerme

Artemisia nova/Stipa comata

Mueggler and Stewart (1980) western Montana

Artemisia arbuscula/Agropyron spicatum

Artemisia arbuscula/Festuca idahoensis

Hironaka et al. (1983) southern Idaho

Artemisia arbuscula/Poa sandbergii

Artemisia arbuscula/Agropyron spicatum

Artemisia arbuscula/Festuca idahoensis

Artemisia longiloba/Festuca idahoensis

Artemisia nova/Agropyron spicatum

Artemisia nova/Festuca idahoensis

Artemisia rigida/Poa sandbergii

Johnson (1987) northeastern Oregon

Artemisia rigida/Poa sandbergii
7

Table 1—Relations between rangeland potential vegetation types found within the interior

Columbia basin and previously published habitat type classificationsa (continued)

Potential vegetation type (PVT) Prior habitat type classificationsb

Low sagebrush–mesic Zamora and Tueller (1973) northern Nevada

with juniper Artemisia arbuscula/Stipa thurberiana

Artemisia arbuscula-Purshia tridentata/Agropyron spicatum

Artemisia arbuscula/Festuca idahoensis

Artemisia longiloba/Festuca idahoensis

Artemisia nova/Agropyron spicatum

Artemisia nova/Agropyron inerme

Artemisia nova/Stipa comata

Hironaka et al. (1983) southern Idaho

Artemisia arbuscula/Poa sandbergii

Artemisia arbuscula/Agropyron spicatum

Artemisia arbuscula/Festuca idahoensis

Artemisia longiloba/Festuca idahoensis

Mountain big sagebrush– Mueggler and Stewart (1980) western Montana

mesic east Artemisia tridentata /Festuca idahoensis

Artemisia tridentata /Festuca scabrella

Hironaka et al. (1983) southern Idaho

Artemisia tridentata subsp. vaseyana/Agropyron spicatum

Artemisia tridentata subsp. vaseyana/Festuca idahoensis

Artemisia tridentata subsp. vaseyana-Symphoricarpos oreophilus/

Agropyron spicatum

Artemisia tridentata subsp. vaseyana-Symphoricarpos oreophilus/

Festuca idahoensis

Mountain big sagebrush– Hironaka et al. (1983) southern Idaho

mesic east with conifers Artemisia tridentata subsp. vaseyana/Agropyron spicatum

Artemisia tridentata subsp. vaseyana/Festuca idahoensis

Artemisia tridentata subsp. vaseyana-Symphoricarpos oreophilus/

Agropyron spicatum

Artemisia tridentata subsp. vaseyana-Symphoricarpos oreophilus/

Festuca idahoensis

Mountain big sagebrush– Daubenmire (1970) eastern Washington

mesic west Artemisia tridentata subsp. vaseyana/Festuca idahoensis

Hironaka et al. (1983) southern Idaho

Artemisia tridentata subsp. vaseyana/Agropyron spicatum

Artemisia tridentata subsp. vaseyana/Festuca idahoensis

Artemisia tridentata subsp. vaseyana-Symphoricarpos oreophilus/

Agropyron spicatum

Artemisia tridentata subsp. vaseyana-Symphoricarpos oreophilus/

Festuca idahoensis

Johnson (1987) northeastern Oregon

Artemisia tridentata subsp. vaseyana/Festuca idahoensis

Artemisia tridentata subsp. vaseyana-Symphoricarpos oreophilus/

Bromus carinatus
8

Table 1—Relations between rangeland potential vegetation types found within the interior

Columbia basin and previously published habitat type classificationsa (continued)

Potential vegetation type (PVT) Prior habitat type classificationsb

Mountain big sagebrush– Hironaka et al. (1983) southern Idaho

mesic west with juniper Artemisia tridentata subsp. vaseyana/Festuca idahoensis

Artemisia tridentata subsp. vaseyana-Symphoricarpos oreophilus/

Festuca idahoensis

Wheatgrass grassland Daubenmire (1970) eastern Washington

Agropyron spicatum/Poa secunda

Agropyron spicatum/Festuca idahoensis

Mueggler and Stewart (1980) western Montana

Agropyron spicatum/Agropyron smithii

Agropyron spicatum/Poa sandbergii

Tisdale (1986) central Idaho

Apropyron spicatum-Poa sandbergii/Balsamorhiza sagittata

Agropyron spicatum/Opuntia polyacantha

Johnson (1987) northeastern Oregon

Agropyron spicatum/Eriogonum heracleoides

Agropyron spicatum/Poa sandbergii

Agropyron spicatum-Poa sandbergii/Scutellaria angustifolia

Agropyron spicatum-Poa sandbergii/Astragalus cusickii

Agropyron spicatum-Poa sandbergii/Erigeron pumilus

Agropyron spicatum-Poa sandbergii/Phlox colubrina

Agropyron spicatum-Poa sandbergii/Opuntia polyacantha

Antelope bitterbrush Daubenmire (1970) eastern Washington

Purshia tridentata/Stipa comata

Purshia tridentata/Agropyron spicatum

Purshia tridentata/Festuca idahoensis

Mueggler and Stewart (1980) western Montana

Purshia tridentata/Agropyron spicatum

Purshia tridentata/Festuca idahoensis

Purshia tridentata/Festuca scabrella

Hironaka et al. (1983) southern Idaho

Purshia tridentata/Stipa comata

Purshia tridentata/Agropyron spicatum

Johnson (1987) northeastern Oregon

Purshia tridentata/Festuca idahoensis-Agropyron spicatum

Purshia tridentata/Agropyron spicatum

Mountain shrub Mountain shrub habitat types have not been described for

the basin.

Fescue grassland Daubenmire (1970) eastern Washington

Festuca idahoensis/Symphoricarpos albus

Festuca idahoensis/Rosa nutkana
9

Table 1—Relations between rangeland potential vegetation types found within the interior

Columbia basin and previously published habitat type classificationsa (continued)

Potential vegetation type (PVT) Prior habitat type classificationsb

Fescue grassland Mueggler and Stewart (1980) western Montana

 (continued) Festuca scabrella/Festuca idahoensis

Festuca idahoensis/Agropyron spicatum

Festuca idahoensis/Carex filifolia

Festuca idahoensis/Stipa richardsonii

Festuca idahoensis/Deschampsia caespitosa

Tisdale (1986) central Idaho

Festuca idahoensis/Agropyron spicatum

Festuca idahoensis/Koeleria cristata

Carex hoodii/Festuca idahoensis

Johnson (1987) northeastern Oregon

Festuca viridula/Lupinus laxiflorus

Festuca idahoensis/Koeleria cristata

Festuca idahoensis/Agropyron spicatum

Festuca idahoensis-Agropyron spicatum/Lupinus sericeus

Festuca idahoensis-Agroptron spicatum/Balsamorhiza sagittata

Festuca idahoensis-Agropyron spicatum/Phlox colubrina

Festuca idahoensis/Carex hoodii

Fescue grassland with conifers Mueggler and Stewart (1980) western Montana

Festuca scabrella/Festuca idahoensis

Festuca idahoensis/Agropyron spicatum

Festuca idahoensis/Carex filifolia

Festuca idahoensis/Stipa richardsonii

Festuca idahoensis/Deschampsia caespitosa

Tisdale (1986) central Idaho

Festuca idahoensis/Agropyron spicatum

Festuca idahoensis/Koeleria cristata

Festuca viridula/Lupinus laxiflorus

Johnson (1987) northeastern Oregon

Festuca viridula/Lupinus laxiflorus

Festuca idahoensis/Koeleria cristata

Festuca idahoensis/Agropyron spicatum

Festuca idahoensis-Agropyron spicatum/Lupinus sericeus

Festuca idahoensis-Agroptron spicatum/Balsamorhiza sagittata

Festuca idahoensis-Agropyron spicatum/Phlox colubrina

Festuca idahoensis/Carex hoodii

a

 Johnson (1987) classified vegetation into “plant associations” rather than the landscape into “habitat types.”

b

 Habitat type names included are those used by the authors. Plant nomenclature can be updated with the USDA

NRCS plants database.
10

Table 2—General site characteristics of potential vegetation types found within the interior

Columbia basin (all lands)

Potential vegetation General site characteristics (areal extent within the basin

type (PVT) in million ha)a

Typically occurs on poorly drained flats or basins with saline soils in a

mosaic with slopes and ridges containing Wyoming big sagebrush–warm

PVT or as a zone that receives less than 30 cm precipitation; typically

<2000 m elevation. Less extensive areas also occur on upland soils derived from marine or other highly saline sediments. (0.86)

Encompasses the lower elevation (<2000 m) and more arid portion of the

Wyoming big sagebrush zone, typically <2000 m elevation and receiving

less than 30 cm of precipitation. Common on semiarid valley bottoms

and lower mountain slopes. A dominant PVT of Snake River plain, southeastern Oregon, and central Washington. (9.59)

Encompasses the higher elevation (>1000 m) and colder portion of the

Wyoming big sagebrush zone. This PVT has a more continental climatic

regime and colder winter temperatures that limit influence of annual grasses more than in the Wyoming big sagebrush–warm PVT. Common in valley

bottoms and lower slopes of cental Oregon, northern Nevada, eastern Idaho, and southwestern Montana. (0.66)

Generally occurs on lower elevation deep soils within the basin. Because of

the potential productivity of these soils, much of the original area has been

converted to agricultural use. Remaining areas are typically smaller patches surrounded by Wyoming big sagebrush–warm PVT sites with shallower

soils. This PVT produces structures that are 1 to 3 m tall, depending on

age of sagebrush and soil productivity. (0.73)

Widespread geographically throughout sagebrush-dominated portion of the

basin but seldom locally abundant. Found intermixed with Wyoming big

sagebrush vegetation but typically on north or east slopes. This PVT is

most prevalent in southeastern Idaho and southwestern Montana where

summer precipitation is not as limiting. This sagebrush species resprouts

after fire, but this varies widely locally. (0.18)

Dominated by winterfat that occurs in a mosaic with Wyoming big sagebrush communities. The mosaic is determined primarily by the salinity

of the sediment-derived soils. Understory includes Gardner’s or sickle saltbush and Sandberg bluegrass. Sites often are dominated by cheatgrass

after fire. (0.36)

Sites dominated by one of several species of dwarf sagebrushes including

low, stiff, black, Owyhee, and little sagebrush. Low sagebrush is the most

extensive in the basin. This PVT generally occurs on distinctive soils that

differentiate the sites from those supporting the surrounding big-sagebrushdominated PVTs. Stiff sagebrush also occurs in association with wheatgrass grassland and dry forest PVTs. Herbaceous coverage and production

are less than in surrounding PVTs. (0.74)

Sites are similar to low sagebrush–mesic but occur in association with

juniper woodlands. (0.05)

Salt desert shrub

Wyoming big sagebrush–

 warm

Wyoming big sagebrush–

 cool

Basin big sagebrush

Threetip sagebrush

Low sagebrush–xeric

Low sagebrush–mesic

 with juniper

Low sagebrush–mesic
11

Typically dominated by mountain big sagebrush, other shrubs species, and

a variety of herbaceous species. Occurs primarily in valley bottoms and

mountain slopes in southwestern Montana and eastern Idaho. Much of this

PVT had a shorter fire return interval during historical times, and changes

in composition such as increased sagebrush coverage and decreased

herbaceous species coverage reflect this decrease in fire occurrence. Invasive annual grasses are present but have not affected the dynamics of

disturbance and composition to the extent of many other sagebrush

steppe vegetation types. (1.92)

Composition and geographical range is similar to that of the mountain big

sagebrush–mesic east PVT except having a greater conifer component.

Historically this PVT probably occurred as a mosaic of mature conifer

stands interspersed with grassland, mountain big sagebrush steppe,

young developing conifer, and mature conifer communities. Decreased fire

occurrence has resulted in more continuous conifer overstory development

and conifer expansion into adjacent sagebrush-dominated communities.

(0.09)

Common on mid to upper mountain slopes from central Oregon to southwest and south-central Idaho. Often occurring within the Wyoming big

sagebrush–warm PVT or on opposing north-facing more moist slopes

and the coniferous zone; typically at elevations >1000 m. (1.18)

Similar in composition to the mountain big sagebrush–mesic west PVT and

occurs at the contact between the sagebrush steppe and juniper woodland

zones in the basin; typically >1000 m elevation. Juniper woodland is the

late seral stage of this PVT. Common from central Oregon east to southwest and south-central Idaho. (1.31)

Once extensive on canyon and lower valley slopes throughout the central

portions of the basin. Additional areas known as the Palouse Grassland

were found in southeastern Washington, northeastern Oregon, and northern Idaho, but these have largely been converted to agricultural use. (0.63)

Typically found in a mosaic of dry forest and mountain big sagebrush–mesic

west PVTs in north-central Washington and southern Oregon. Usually located on coarse-textured soils and dry aspects. Herbaceous understory

often is altered by past livestock grazing and invasive species. (0.18)

Occurs at the transition between the upper shrub steppe and dry forest

PVTs and includes a variety of shrub species common to these communities. May also occur as stringers of shrub-dominated vegetation in the

draws of upper watersheds. (0.03)

Occurs at transition between wheatgrass grassland and coniferous forest

PVTs in northern Montana, central Idaho, and northeastern Oregon. Composition is usually dominated by rough fescue, Idaho fescue, and bluebunch wheatgrass. (0.29)

Table 2—General site characteristics of potential vegetation types found within the interior

Columbia basin (all lands) (continued)

Potential vegetation General site characteristics (areal extent within the basin

type (PVT) in million ha)a

Mountain big sagebrush–

 mesic east

Mountain big sagebrush–

 mesic east with conifers

Mountain big sagebrush–

 mesic west

Mountain big sagebrush–

 mesic west with juniper

Wheatgrass grassland

Antelope bitterbrush

Mountain shrub

Fescue grassland
12

Herbaceous composition similar to fescue grassland PVT but occurring in a

mosaic of coniferous forest PVTs. Often contains sparse overstory of conifers such as Douglas-fir and lodgepole pine. Most common in western

Montana, and northeastern Oregon. (1.39)

Fescue grassland with

 conifers

Table 2—General site characteristics of potential vegetation types found within the interior

Columbia basin (all lands) (continued)

Potential vegetation General site characteristics (areal extent within the basin

type (PVT) in million ha)a

Salt Desert Shrub PVT

The salt desert shrub PVT is often dominated by

one or more species of shrubs or half-shrubs in

the Chenopodiaceae and Asteraceae families

(Blaisdell and Holmgren 1984) (figs. 3 and 4). A

large number of species occur in the salt desert

shrub communities. However, in any given site, a

relatively simple composition exists because the

species distributions vary in relation to gradients

of salinity and aridity (Knight 1994, West 1988).

Common plant community dominants occurring in

this PVT include black greasewood,1 fourwing

saltbush, winterfat, shadscale, and budsage. As

salinity increases, the site is dominated by winterfat, shadscale, Gardner’s saltbush and finally

black greasewood. Greasewood also occupies

the less arid sites. Herbaceous plant coverage

is sparse.

Biological soil crusts are a critical component of

salt desert shrub vegetation, providing soil stability

and nutrient input into the ecosystem (Mayland

et al. 1966, West and Skujins 1977). They appear

to be more resilient to livestock use when wet

during spring than later in the year when they

become more susceptible to mechanical damage

(Anderson et al. 1982a, 1982b). Johansen et al.

(1984) found that wildfire severely reduced biological soil crusts in a shadscale-greasewood

community. Moss and algal coverage recovered

within 5 years postburn. Lichen coverage, however, was less than 50 percent of the unburned

sites after 5 years.

Livestock and feral horse grazing has affected

extensive areas, particularly during the first half

of the 20th century. Subsequently, invasive species have entered many areas of this PVT.

During years with above-average precipitation,

annual grasses may develop herbaceous biomass

capable of supporting unwanted wildland fire

(wildfires) (Pellant and Reichert 1984). Fire occurrence further favors communities dominated

by annual grasses.

Slightly altered salt desert shrub sites usually

have relatively intact shrub components. Invasive

annuals are often present in low amounts. These

sites are unlikely to burn because they have little

fine fuel except after periods of above-average

precipitation (Knight 1994, Pellant and Reichert

1984). Once fire occurs, however, invasive annuals increase greatly, increasing the probability of

subsequent fires. The salt desert shrub PVT often occurs in a mosaic with the Wyoming big

sagebrush–warm PVT, which has greater biomass production and fire potential. Fire often

starts in this PVT and spreads to salt desert

shrub communities.

Severely altered salt desert shrub sites typically

have lost shrub and half-shrub components and

have become dominated by invasive annual

grasses and forbs. Natural recruitment of native

species is inhibited by competition from annual

species, lack of seed sources, recurrent fires, and

herbivory. Once burned, these sites often become

dominated by annual grasses, increasing the risk

of subsequent fire occurrence. Frequent fires

may preclude reestablishment of the native shrub

component and increase the extent of the disturbed area.

1 Plant taxonomy nomenclature follows that used by the

USDA Natural Resources Conservation Service (USDA

NRCS 2001; see app. 2).

a

 Area of PVTs is from unpublished ICBEMP data on file with: USDA Forest Service, Pacific Northwest Research Station,

P.O. Box 3890, Portland, OR 97208.