United States

Department

of Agriculture

Forest Service

Rocky Mountain

Research Station

General Technical

Report RMRS-GTR-104

June 2003

Indicators of Rangeland

Health and Functionality

in the Intermountain West

Renee A. O’Brien

Curtis M. Johnson

Andrea M. Wilson

Van C. Elsbernd
The Authors

Renee A. O’Brien is Lead Ecologist and Analysis Team Leader with the Interior West Forest

Inventory and Analysis Program at the Rocky Mountain Research Station in Ogden, UT. She holds

a B.S. degree in botany from Weber State University and B.S. and M.S. degrees in range science

from Utah State University.

Curtis M. Johnson is Regional Rangeland Ecosystem Specialist for the Intermountain Region of

the Forest Service in Ogden, UT. He holds a B.S. degree in forest management from Humboldt State

University and a M.S. degree in watershed management from the University of Arizona.

Andrea M. Wilson was an Analyst with the Interior West Forest Inventory and Analysis Program at

the Rocky Mountain Research Station in Ogden, UT. She holds B.S. and M.S. degrees in Forestry

from Northern Arizona University.

Van C. Elsbernd is a national Rangeland Specialist for the Washington Office of the Forest Service

located in Fort Collins, CO. He has a B.S. degree in forest and rangeland management from the

University of Montana.

Acknowledgments

The authors gratefully acknowledge the cooperation between the Interior West Forest Inventory

and Analysis Program and the Intermountain Region of the USDA Forest Service to make this

technical reference possible. The authors especially thank Doug Myers (retired), Forest Inventory

and Assessment Group Leader at the Intermountain Region, for encouraging indicator development.

Appreciation is also extended to Levi Broyles of the Bridger-Teton National Forest rangeland

and timber staff and Dave Tart, Intermountain Region Ecologist, for input and review of indicator

development. Special thanks also go to Dr. John Mitchell, Dr. Phillip L. Simms, Tom Roberts,

Dr. Chris Lauver, Larry De Blander, and Sharon Woudenberg for their reviews.

Abstract

O’Brien, Renee A.; Johnson, Curtis M.; Wilson, Andrea M.; Elsbernd, Van C. 2003. Indicators of rangeland

health and functionality in the Intermountain West. Gen. Tech. Rep. RMRS-GTR-104. Ogden, UT: U.S.

Department of Agriculture, Forest Service, Rocky Mountain Research Station. 13 p.

Rangelands comprise about 42 percent of the land area of the United States and provide vital land functions

such as watershed, multiple-use, recreation, and other amenities. Currently, we do not know the status and

trends of many of our nation’s rangelands, and consistent protocols for describing rangeland system dynamics

across land management agencies are lacking. Various Federal land management agencies have responsibility for rangeland inventory and assessments that characterize the health of the nation’s rangelands. Many

efforts have been initiated to standardize an approach to large-scale monitoring and assessment of rangelands,

but none are universally accepted.

This paper describes four rangeland health indicators and interpretation criteria that can be used to

characterize rangeland health and functionality. The four indicators tested in this study—noxious weeds, ground

cover, species composition, and shrub cover—proved to be viable indicators of rangeland health and

functionality. The paper recommends that these indicators can be used at many scales, from the site level for

local planning, to State and national levels for strategic planning.

Keywords: rangeland health, functionality, indicators, bare ground, noxious weeds, species composition
Contents

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

Study Objectives ..................................................................................................... 1

Indicators of Rangeland Health and Functionality .................................................. 2

Methods ...................................................................................................................... 3

Results and Discussion ............................................................................................... 4

Develop Indicators of Rangeland Health and Functionality .................................... 4

Value of FIA Data and Grid for Evaluating Rangeland Health ................................ 7

Reliability and Precision of the Indicators ............................................................... 8

Bridger-Teton Cover Types at Risk ........................................................................ 9

Recommendations ...................................................................................................... 9

References ................................................................................................................ 10

Appendix A—Plant species designated as noxious weeds in Wyoming ................... 11

Appendix B—References for ground cover criteria for threshold

watershed protection in the Intermountain West as it relates to

properly functioning condition for rangeland health .......................................... 12

Appendix C—Plants needed with at least 5 percent canopy cover in

each Society for Range Management cover type to be at potential natural

community ecological status ............................................................................ 13

Cover photo courtesy of Curt Johnson

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-104. 2003 1

Introduction ____________________

Rangelands provide vital watershed, multiple-use,

and amenity land functions. An estimate of the area of

rangeland in 1992 in the continental United States is

801 million acres (Mitchell 2000), which is about 42

percent of the total land area. Currently, we do not

know the status and trend of many of our nation’s

rangelands, and we lack consistent protocols for describing rangeland system dynamics across land management agencies. Various Federal land management

agencies have responsibility for rangeland inventory

and assessments that characterize the health of the

nation’s rangelands. Several efforts have been initiated by these agencies to standardize an approach to

large-scale rangeland monitoring, but none are universally accepted. There is a need for a rangeland

inventory and assessment protocol that is consistent,

quantitative, relatively inexpensive, repeatable, systematic, statistically sound, and can be accomplished

with minimal technical skills.

Qualitative, descriptive rangeland health concepts

have been described in range health checklists developed by the National Research Council (1994) and

the USDI Bureau of Land Management (BLM) (2000).

Taking a more quantitative approach, a study of

rangeland health indicators was conducted on the

Bridger-Teton National Forest by the Interior West

Forest Inventory and Analysis (IW-FIA) Program

within the Rocky Mountain Research Station of the

USDA Forest Service. Forest Inventory and Analysis

(FIA) is a national program that conducts inventories

for large-scale planning and monitoring on all forest

land in the United States, including both public and

private ownerships. FIA sampling procedures for

forest lands are well documented and standardized

nationally (USDA Forest Service 2001). IW-FIA is

one of five regional FIA programs and conducts inventories in eight Interior West States as part of its

national FIA responsibilities.

IW-FIA conducted an inventory on the Bridger-Teton

during 1998 through 2001. FIA has not traditionally

Indicators of Rangeland Health

and Functionality in the

Intermountain West

Renee A. O’Brien

Curtis M. Johnson

Andrea M. Wilson

Van C. Elsbernd

sampled nonforested lands, those with less than 5

percent tree canopy cover or less than 10 percent

stocked by trees of any size. However, as much as 30

percent of National Forest System lands are classified

as nonforest. Nonforest land is often referred to as

rangeland, but rangeland is not restricted to nonforest

types. Therefore, all cover types on the Bridger-Teton,

both forest and nonforest, were included in this study

using the systematic FIA sample selection grid and

the portion of the FIA protocols that were relevant to

rangelands. An analysis was completed to determine

if the information collected on all Bridger-Teton plots

could be used to summarize the health and functionality of the Bridger-Teton rangelands. For this pilot

study, the interpretation criteria for functionality were

that a site was either in proper functioning condition,

or functioning at risk. Functioning at risk means

health and sustainability are threatened. A

nonfunctioning category was not used in this pilot

because that threshold has not yet been defined. The

threshold for functioning at risk was based on data

collected on rangelands in the Intermountain Region,

combined with professional judgment (appendix B;

Johnson and Elsbernd 1997; USDA Forest Service

1996).

Riparian areas occupy a small proportion of a landscape (usually less than 2 percent) and are typically

linear landscape features. Riparian areas are often

missed using the systematic FIA sample grid and

therefore were not included in this study. Because

they are not adequately sampled with the FIA grid,

they must be sampled using other methods. One such

procedure that handles riparian area monitoring and

analysis is outlined in Winward (2000).

Study Objectives

1. Develop indicators of rangeland health and

functionality.

2. Test the value of FIA data for evaluating the

indicators, and demonstrate use of the FIA grid

and data collection protocol for rangeland health.
2 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-104. 2003

3. Identify cover types currently in proper functioning condition or functioning at risk on the

Bridger-Teton.

Indicators of Rangeland Health and

Functionality

1. Noxious Weeds—These are plants that are designated as noxious weeds by the Secretary of Agriculture or by an appropriate State official. A comprehensive list of state and federally designated noxious

weeds for Wyoming is presented in appendix A. For

this paper, a potential new invader from adjacent

States was added to the list. Noxious weeds generally

possess one or more of the following characteristics:

aggressive and difficult to manage, poisonous, toxic,

parasitic, invasive, and new or not common to the

United States.

Data collection focused on determining the presence

or absence of a noxious weed on a sample location. The

interpretation for this indicator was that if any noxious weed was found on a sample site the acres represented by that sample were determined to be at risk

from both a health and sustainability viewpoint, even

if the ground cover was adequate for a properly functioning watershed. This interpretation was made because of the aggressive nature of noxious weeds in both

pristine and disturbed landscapes.

2. Ground Cover—A stable and sustainable soil

base is needed for rangeland watersheds to yield a

variety of multiple-use products, services, and amenities (Ellison and others 1951). The soil base, no matter

what the soil classification, needs an adequate ground

cover of vegetation, litter, and rock for protection from

rain, erosion, and use. Qualitative rangeland health

and functionality checklists in the literature have a

majority of indicators and descriptors focusing on

various aspects of ground cover. For example, in BLM

(2000), 11 of the 17 indicators deal with some aspect of

ground cover protection, such as rills, water flow

patterns, bare ground, soil surface resistance to erosion, and litter amount. The other indicators in the

literature deal with the vegetation on the site, addressed below in the species composition indicator

tested in this pilot.

Using the Society for Range Management (SRM)

cover types (Shiflet 1994) as the broad-scale vegetation classification base, ground cover threshold levels

were developed to represent the threshold point at

which a site in a particular cover type would begin to

lose basic functionality defined by increased soil

erosion and loss of site sustainability. Ground cover is

defined as basal vegetation, litter, moss/lichen, or rock

greater than 3

⁄4-inch diameter. The minimum ground

cover needed for proper functioning sustainable

watersheds for the four Bridger-Teton cover types

used in this pilot are:

Cover type Percent ground cover

Aspen 95

Alpine 90

Mountain big sagebrush 85

Tall forb 80

The ground cover threshold values for watershed

protection used in this study were derived from baseline

material collected throughout the Intermountain Region from healthy and functional rangelands (appendix B). The data were averaged across the Intermountain Region, modified for the Bridger-Teton, and

summarized in Johnson and Elsbernd (1997). Cover

types with ground cover levels below these minimum

thresholds were determined to be functioning at risk

for basic watershed protection.

A separate study conducted by Hardy (2002) assessed the applicability of using soil physical and plant

cover categories to predict Erosion Condition Class for

two major community types, mountain sagebrush and

mountain grassland, at the broad scale of FIA. Erosion

Condition Class is a tool developed by the BLM to

quantify levels of erosion at a given site. Seventeen

variables were tested for significance in predicting site

scores for Erosion Condition Class. Of those 17 variables, percent bare ground was the only significant

variable at the site level (p < .001).

3. Species Composition—Determining if the

proper vegetation is present on a site is the most

difficult question in the rangeland health discussion.

A general evaluation of ecological status may be conducted using a basic species composition list; however,

species lists would probably need to be revised to

adequately assess a site’s ability to meet more specific

health or other management objectives. An attempt

was made at describing the desired predominant species that should be present if the Society for Range

Management cover type was in potential natural community ecological status, with the understanding that

a potential natural community species composition

would not meet all desired plant community compositions. For this first approximation, predominant species are defined as species present with at least 5

percent canopy cover. This was done because FIA

protocols limit the field recording of species to those

with 5 percent or greater cover. The desired potential

natural community plant species components are listed

for each cover type in appendix C.

A site was considered to be functioning at risk if at

least one listed potential natural community plant

species was not present with at least 5 percent cover.

These interpretation criteria will change if the goal

changes from meeting the potential natural community
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-104. 2003 3

criteria to species composition desirable for a specific

purpose such as forage production, sage grouse habitat, low risk wildfire community, or a visually pleasing

wildflower setting in a sagebrush community.

4. Shrub Cover—Many rangelands across the

United States have a major shrub component. As an

example, much of the Intermountain region is occupied by sagebrush (Artemisia spp.). Because of ecological processes such as fire, insects and disease, and

normal life cycles, sagebrush ecosystems naturally

have a broad range of self-sustaining communities

with a variety of age classes and structures. Such a

mix of components provides a variety of habitat and

food that benefit an assortment of wildlife and domestic animals, along with a diversity of visual and watershed aspects across the landscape.

The approach taken with sagebrush cover is slightly

different from the approach taken with the first three

indicators. Instead of rating an individual site’s health

and aggregating those ratings to represent the health

of the cover type, this indicator only assesses the

properly functioning aspect of the entire cover type. It

is essentially a landscape level indicator. The desired

mix of cover classes for sustainable sagebrush ecosystems for all ecological purposes and needs (USDA

Forest Service 1996) was determined to be:

• 10 percent of the sagebrush area has 0 to 5 percent

shrub canopy cover

• 50 percent of the sagebrush area has 6 to 15

percent shrub canopy cover

• 40 percent of the sagebrush area has greater than

15 percent shrub canopy cover

If the mix of sagebrush cover is outside the desired

cover class distribution, the cover type may be functioning at risk for the overall ecological health and

diversity of a sustainable sagebrush community at a

landscape level.

Methods _______________________

FIA inventories provide a statistical-based sample

of forest resources across all ownerships that can be

used for planning and analysis at a National Forest or

BLM District; and State, regional, and national levels.

The sample was designed to meet national standards

for precision in State and regional estimates of forest

attributes. IW-FIA uses a two-phase sampling procedure. Field crews normally conduct the field phase of

the inventory only on forest land, but for this study,

plots were established on all grid points, including

nonforest. The sampling intensity is one field plot

every 5,000 m, or about every 3 miles.

The Bridger-Teton is located in the Greater

Yellowstone Ecosystem in western Wyoming. It is the

largest National Forest in the continental United

States, with 3.4 million acres, of which approximately

30 percent is nonforest. IW-FIA sample grid plots were

established on the Bridger-Teton between 1998 and

2001. There were 557 plots, of which 382 were classified with a forest location center, 159 were classified

with a nonforest location center, 15 were inaccessible,

and one was water. Each sample on the grid represents approximately 6,000 acres of land.

Data from both forest and nonforest plots were

used to evaluate the rangeland health indicators,

with the exception of the shrub cover indicator that

only used the mountain big sagebrush cover type.

The cover types chosen for the pilot study included

aspen, alpine, mountain big sagebrush, and tall forb.

Plots were assigned to the aspen type based on the

FIA forest type classification. Field crews assigned

the plots on nonforest types to Society for Range

Management cover types based on the general descriptions available in Shiflet (1994). These four

types were selected for this study based on adequate

sample size. Forest procedures were adapted to the

nonforest (rangeland) plots by using a subset of FIA

measurement variables (USDA Forest Service 1998)

that were relevant to nonforest conditions. These

included physiographic variables (elevation, slope,

and aspect), understory vegetation, and ground cover.

The layout of the field plot, which comprises four

subplots, is shown in figure 1.

.

 Subplot

 (1/24-acre,

24 ft radius)

1

2

4 3

Four-25 foot ground cover

transects per subplot

Distance between

subplot centers is

120 ft

.

.

. .

Location center

(LC)

Figure 1—Field plot layout.
4 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-104. 2003

Noxious Weeds—Field crews were trained in the

identification of plants listed as noxious or invasive in

the State of Wyoming and surrounding States. The

presence of any noxious weeds was recorded by species

and subplot.

Ground Cover—Ground cover was identified on

400 points per plot. Using a tape measure, 25-foot

transects were laid out in the four cardinal directions

for each of the four subplot centers. Beginning at the

1-foot mark, the tip of a plot stake or sharply pointed

staff was placed on the ground surface along the side

of the tape at each 1-foot mark, and ground cover was

recorded at each point by category of cover. The categories were bare ground, pavement (pebbles between 1

⁄8

and 3⁄4 inches diameter), rocks (3⁄4 inches diameter or

greater), litter, moss/lichens, basal vegetation, and

other. For this study, pavement cover percentages

were combined with bare ground because material

between 1⁄8 and 3⁄4 inch does not impede raindrop

erosional impact. The transect layout was chosen for

efficiency for field crews and was similar to other FIA

protocols. The fact that transects radiate out from the

center of the subplot may oversample the center of the

subplot (see “Recommendations” section for more discussion of the transect configuration). For each plot,

the percent ground cover was estimated by dividing

the number of points not on bare ground by the total

number of sampled points on each plot. The estimate

was then averaged over all the plots in the cover

type to obtain the final estimate. The standard error

of the final estimate was calculated using the assumption that the plot level estimates were normally distributed.

Species Composition and Shrub Cover—For

each subplot (four per location), up to four species that

had 5 percent cover or greater were listed within each

life form (tree seedlings/saplings, shrubs, forbs, or

graminoids). Percent cover for each species listed was

ocularly estimated and recorded. Total percent cover

was also ocularly estimated and recorded for each life

form that occurred on each subplot. A maximum of

four species were recorded on each subplot per life

form, so it is possible that some species with 5 percent

or greater cover were present on a subplot yet not

recorded. For this study, all the species on all four

subplots were combined into one list for each location.

Results and Discussion __________

The objectives of this study were to (1) develop indicators of rangeland health and functionality, (2) test the

value of FIA data for evaluating the indicators, and

demonstrate use of the FIA grid and data collection

protocol for rangeland health, and (3) identify cover

types currently in proper functioning condition, or

functioning at risk on the Bridger-Teton.

Develop Indicators of Rangeland Health

and Functionality

The four indicators of rangeland health and functionality presented in this paper were shown to be

useful for describing rangelands in the Intermountain

West and could be applicable across the United States.

Used together, the four indicators can describe the

health and functionality of rangelands at many scales.

Noxious Weeds—The noxious weed indicator was

applied to all the cover types on the Bridger-Teton,

including all the coniferous forest types. Three percent

of the sampled locations (14 of 542 plots) had at least

one noxious weed species present. Five of the locations

with noxious weeds present were in the spruce-fir

cover type, four were in the Douglas-fir type, two were

in the aspen type; and one each were in the lodgepole,

tall forb, and mountain big sagebrush types. Weed

occurrence is typically associated with roads and trails,

and is not spread uniformly across the landscape. It is

therefore probably not reasonable to expand these

plot-based detections in the same way that FIA expands other forest attributes to get population estimates. A separate inventory of noxious weeds conducted by Bridger-Teton personnel in 2001 indicated

that about 6,712 acres had noxious weeds present.

One noxious weed, Canada thistle, often occurs as

a disturbance component in many coniferous forest

types. Its occurrence fluctuates with canopy closure,

and therefore “risk” may not be indicated just by its

presence.

Tracking the trend of noxious weed plant spread

through number of plot occurrences could indicate a

trend in rangeland sustainability. Figure 2 shows the

rough location of FIA plots having weed species on the

Forest, and table 1 lists the noxious weed species

found by number of plots.

Ground Cover—The percent ground cover results

for the four cover types analyzed on the Bridger-Teton

are compared to the desired ground cover thresholds

in figure 3. The results of the FIA estimates of bare

ground are presented with a 95 percent confidence

range on the estimated mean. The estimated average

ground cover for the aspen type on the Bridger-Teton

is 90 percent, plus or minus 5, compared to the 95 percent

ground cover needed for the type to be considered

healthy and properly functioning for watershed protection and soil sustainability and recovery. The estimated average ground cover for the alpine cover type is

68 percent, plus or minus 10, compared to the threshold value of 90. The estimated average ground cover

for the tall forb type is 67 percent, plus or minus 6,
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-104. 2003 5

Figure 2—Noxious weeds on FIA sample locations on the Bridger-Teton National Forest.
6 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-104. 2003

Table 1—Noxious weed species found by number

of locations on the Bridger-Teton National

Forest. The 14 plots represent 3 percent

of the total 542 sample plots.

Noxious weed Number of

species found locations

Canada thistle

(Cirsium arvense) 9

Scotch thistle

(Onopordum acanthium) 3

Plumeless thistle

(Carduus acanthoides) 1

Musk thistle

(Carduus nutans) 1

Common St. Johnswort

(Hypericum perforatum) 1

Dyer’s Woad

(Isatis tinctoria) 1

Tall forb estimate

Tall forb threshold

Mountain Big Sagebrush

estimate

Mountain Big Sagebrush

threshold

Alpine estimate

Alpine threshold

Aspen estimate

Aspen threshold

0 10 20 30 40 50 60 70 80 90 100

Cover type 

Percent

Figure 3—Estimated percent ground cover compared to proper physical functioning threshold by cover type,

Bridger-Teton National Forest, 1999.

compared to the threshold value of 80. The estimated

average ground cover for the mountain big sagebrush

type is 77 percent, plus or minus 5, compared to the

threshold value of 85. The range of ground cover

estimates for the alpine, tall forb, and mountain big

sagebrush types were all below the desired thresholds,

portraying that ground cover might not be high enough

for adequate watershed and soil protection over a long

period, which may threaten the sustainability of these

types on a Forestwide scale.

Species Composition—Table 2 depicts the results

of the Bridger-Teton plant species sample. These results are based on a comparison of the total species list

for each location, aggregated over all subplots, with

the list of potential natural community species. To be

counted as occurring on the plot, a potential natural

community species had to have at least 5 percent cover

on at least one subplot. The results show that 77 percent

of aspen sites had at least one of the potential natural

community species present, 42 percent had at least

two species present, 25 percent had at least three

potential natural community species present, and 4 percent had at least four species present. There were no

aspen type plots with more than five species from the

list. Of the alpine sites, 63 percent had at least one

potential natural community species present, and 7 percent had two species present. No alpine plots had more

than two species from the list. Of the mountain big

sage sites, 95 percent had at least one of the potential

natural community species present, 69 percent had at

least two species present, 24 percent had at least three

species present, and 7 percent had at least four species

present. No mountain big sage plots had more than

five listed species present. Only 37 percent of tall forb

communities had at least one of the potential natural

community species present, 4 percent had at least two

potential natural community species present, and no
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-104. 2003 7

plots had more than two species. According to the

study criteria, all of the types may be functioning at

risk from a species composition point of view. The

mountain big sage appears to be in the best health

based on list species present with 5 percent cover or

greater. The interpretation of this indicator is problematic, however, and needs more work.

Shrub Cover—Shrub cover results for the mountain big sagebrush cover type on the Bridger-Teton is

given in figure 4. The desired distribution of the

mountain big sagebrush cover type is a cover class mix

of 10 percent with 0 to 5 percent canopy cover, 50

percent with 6 to 15 percent canopy cover, and 40

percent over 15 percent canopy cover. The estimated

amount of the mountain big sage type that is in the

medium class is lower than desired, and the amount in

the high cover class is higher than desired. The confidence interval for estimates of percent shrub cover for

the Bridger-Teton at the 95 percent level is plus or

minus 5. These proportions indicate that the mountain big sagebrush landscape does not meet the desired distribution and may be functioning at risk for

sustainable rangeland sagebrush diversity.

Value of FIA Data and Grid for Evaluating

Rangeland Health

All four indicators used in this determination of the

health and functionality of the Bridger-Teton rangelands can be monitored using FIA protocols. One

criterion cannot stand alone as an ultimate judgment

of any rangeland’s sustainable health or functionality

because of the diversity of rangelands and the complexity of the question. These indicators can be used at

the project scale by Forest Service Ranger Districts

and BLM field offices for site-specific analyses, at

broader scales for Forest and BLM District planning

efforts, or at the State or national scale for broad

strategic-level assessments.

Table 2—Number of potential natural community (PNC) species present on four cover types on the Bridger-Teton National

Forest, listed as a percentage.

Percent of plots Percent of plots Percent of plots Percent of plots Percent of plots

with at least 1 with at least 2 with at least 3 with at least 4 with at least 5

Cover PNC species PNC species PNC species PNC species PNC species

type present present present present present

Aspen 77 42 25 4 2

Alpine 63 7000

Mountain

 big sage 95 69 24 7 4

Tall Forb 37 4000

0

10

20

30

40

50

60

70

80

low cover (0-5%) medium cover (6-15%) high cover (>15%)

Percent area

Desired

distribution

Estimated

distribution

Figure 4—Estimated area of shrub cover by cover class compared with desired area of

shrub cover by cover class for the mountain big sagebrush cover type.
8 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-104. 2003

Noxious Weeds—The presence of noxious weeds

determines whether a rangeland site, landscape, or

watershed is at risk from both a functioning and a

sustainable point of view. The magnitude of the noxious weed problem would influence the questions of

sustainability. The IW-FIA survey is not a census of

noxious weeds but rather a systematic sample that

can provide trend over time.

Ground Cover—This indicator shows which cover

types are properly functioning by providing enough

cover to protect watersheds and soils above an erodibility threshold, and which ones are at risk because of

inadequate surface cover that does not absorb water

and reduce surface impacts. This rangeland watershed health and functionality measurement could be

used at all scales.

Species Composition—The most difficult rangeland health criterion to collect and analyze is species

composition. Whether or not the appropriate plants

are present over a landscape, watershed, or ecosystem

depends on the purpose or objective that is defining a

health or determination call. For this study, referencing each potential natural community’s plants with 5

percent canopy cover or greater answers only the

ecological status question. If the question centers on

health for a threatened, endangered, or sensitive plant

that may need an early seral ecological status to

remain viable and sustainable, the criterion may be

quite different or even the opposite of what was used

in this study. IW-FIA data collection protocols provide data sufficient for some general ecological status

evaluation.

The species composition list in appendix C was

developed through examination of ecological

scorecards, and community and habitat type classification references. This study is intended to be a first

approximation. More work is needed to refine the

species composition lists for each type and to define

desired thresholds for different objectives. Another

approach would be to develop a total cover percentage

for a specific group of species.

Shrub Cover—Shrub cover arranged in a mosaic of

varying densities over a landscape indicates shrub

health regarding sustainability and diversity for a

multitude of habitat values and uses. Shrub cover can

be a primary rangeland health and functionality indicator in the Interior West (especially in the sagebrush

ecosystem) and among some places in the West Coast

and Plains ecosystems. In the national picture it could

certainly indicate health and functionality of a large

percentage of the Western rangelands.

The use of these indicators for the purpose of determining rangeland health and functionality was demonstrated at the National Forest scale. The indicators

can be monitored in the field using FIA protocols.

Although not demonstrated, the authors believe these

indicators could be aggregated for rangeland health

determination at a State or national level, and could

also be utilized for more intensive, smaller scale determinations, such as watersheds, landscapes, or rangeland management units.

Reliability and Precision of the Indicators

Sample estimates are subject to variation. How

much they vary depends on the inherent variability of

the population and on the size of the sample. The FIA

sample was designed to meet national standards for

State and regional estimates of forest attributes. Standard errors, which denote the precision of an estimate,

are presented in table 3 for ground and shrub cover

estimates, along with the number of plots from which

data for each cover type was obtained. The standard

errors of the estimates were calculated using the

assumption that plot level estimates were normally

distributed. A system of computing and reporting

quality assurance of all FIA variables is currently

under development.

Noxious Weeds—The results of this indicator were

reported as noxious weeds being either present or not.

The reliability and precision of this indicator is based

on the ability of FIA field crews to recognize the plant

Table 3—Average cover, standard errors, and number of plots for four cover types on the Bridger-Teton National Forest.

Average shrub Average forb Average grass Average Number of

Cover type cover cover cover ground cover plots

Aspen 12.54 20.57 17.76 89.89 48

SE 1.69 2.4 2.1 2.36

Alpine 1.65 18.52 19.31 67.54 28

SE .81 4.04 3.5 4.95

Mountain big

 sagebrush 26.20 17.96 19.11 77.03 56

SE 2.44 1.82 1.82 2.42

Tall forb 3.48 41.01 18.32 66.89 27

SE .94 4.2 3.25 3.21
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-104. 2003 9

species of concern. In Wyoming, field crews went

through 2 days of training on plant identification,

which included recognition of noxious species. They

were also provided a weed handbook, with color photos

and detailed description of each plant.

Ground Cover and Shrub Cover—Confidence in

the ground and shrub cover estimates is presented by

the standard error of the mean. Standard errors for

ground and shrub cover are presented in table 3. A

confidence interval on the mean was set by multiplying the standard error by a “t” value, in this case 1.96

or 2.0 (depending on sample size) for the 95 percent

confidence level.

Species Composition—As with the noxious weed

indicator, the reliability of this indicator is based on

the ability of field crews to correctly identify the

common species on FIA plots. The variability within

the estimates of cover is presented with standard

errors for each lifeform in table 3.

Bridger-Teton Cover Types at Risk

Aspen—Noxious weeds were present on two aspen

locations. Ground cover averaged 90 percent (plus or

minus 5), which barely encompassed the proper functioning condition threshold of 95 percent for sustained

health and functionality. Of aspen sites, 77 percent

met the minimum species composition requirements

for potential natural community. The results of this

pilot indicate slight risk to health and functionality of

the aspen type on the Bridger-Teton.

Alpine—None of the alpine sample locations had

any presence of noxious weeds. Ground cover averaged 68 percent, plus or minus 10, compared with the

proper functioning condition threshold of 90 percent.

Of the alpine sites, 63 percent met the minimum

species composition requirements for potential natural community. This type is also at risk based on the

ground cover and species composition indicators.

Mountain Big Sagebrush—Noxious weeds were

present on one mountain big sagebrush location.

Ground cover averaged 77 percent, plus or minus 5,

which is lower than the proper functioning condition

threshold of 85 percent. Of the mountain big sagebrush sites, 95 percent met the minimum species

composition requirements for potential natural community. Based on the shrub cover indicator, there is

some risk to the health of the mountain big sagebrush

plant community. To achieve the highest sustainable

diversity for multiple uses, the amount of area in the

6 to 15 percent canopy cover class needs to increase,

and the amount of area in the greater than 15 percent

class needs to decrease.

Tall forb—Noxious weeds were present on one tall

forb location. Ground cover averaged 67 percent plus

or minus 7, compared to the proper functioning condition threshold of 80 percent. Only 37 percent of tall

forb sites met the minimum species composition requirements for potential natural community. Health

and functionality indicators of ground cover and species composition identify this type as being at high risk

on the Bridger-Teton.

Recommendations ______________

The use of these indicators for the purpose of determining rangeland health and functionality was demonstrated at the National Forest scale. Health and

functionality can be monitored using FIA protocols.

Although not demonstrated, the authors believe these

indicators can be aggregated for rangeland health

determination at a State or national level and could

also be utilized for more intensive, smaller scale determinations, such as watersheds, landscapes, or rangeland management units. The summary of these individual data into an analytical health and functionality

judgment at any scale could give a management signal

of the state of our rangelands.

Additional analyses of the ground cover point

transects showed that fewer points may give essentially the same estimate of bare ground that was

obtained with the 400-point sample, with only a slight

decrease in confidence. A more thorough analysis of

quantity of transects needed for estimating percent

bare ground by cover type is under development

(O’Brien and Wilson, in preparation).

The species composition indicator needs more work.

Species lists need to be refined for specific scales and

purposes. The general lists developed for the cover

types used in this study were meant for use at a broad

scale. More specific lists will be more useful at finer

scales.

Additional work is needed to establish thresholds

and properly functioning criteria for other types and

other areas at many scales: other National Forests,

watersheds, ecoregions, and so forth. More work is

also needed to establish thresholds for “nonfunctioning”

rangeland categories.

The sampling design used in this pilot represents an

amalgamation of the Intermountain Region’s standard rangeland assessment techniques and the FIA

sampling protocols. More work is needed, which may

include additional modifications to the design and

validation of the statistical techniques. Subsequent to

the inventory of the Bridger-Teton, to avoid

oversampling the center of the subplot, the configuration of the ground-cover transects was changed in the

FIA protocols to one straight line transect across each
10 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-104. 2003

subplot, instead of four short transects radiating out

from the center. More work is also needed on the

subject of adequate sample size. Sample size may need

to be increased above the intensity of the FIA grid for

some types at some scales in order to decrease variance and increase confidence in the precision of the

estimate.

References _____________________

Ellison, L.; Croft, A.R.; Bailey, R.W. (ed). 1951. Indicators of condition and trend on high range-watersheds of the Intermountain

Region. Agric. Handbook. 19. Washington, DC: U.S. Department

of Agriculture, Forest Service. 66 p.

Hardy, Erik M. 2002. Cover, soil, and physiographic variables

useful in predicting erosion condition class for mountain sagebrush and mountain grassland communities. Fort Collins, CO:

Colorado State University. M.S. Thesis.

Johnson, Curtis M.; Elsbernd, Van C. 1997. Memorandum to the

Washington Office on the National Rangeland Inventory. On file

at: Ogden, UT: U.S. Department of Agriculture, Forest Service,

Intermountain Region. 12 p.

Mitchell, John E. 2000. Rangeland resource trends in the United

States: A technical document supporting the 2000 USDA Forest

Service RPA Assessment. Gen. Tech. Rep. RMRS-GTR-68. Fort

Collins, CO: U.S. Department of Agriculture, Forest Service,

Rocky Mountain Research Station. 84 p.

National Research Council. 1994. Rangeland health—new methods

to classify, inventory, and monitor rangelands. Washington, DC:

Committee on Rangeland Classification, Board of Agriculture.

National Academy Press. 182 p.

O’Brien, Renee A.; Wilson, Andrea, M. [In preparation]. Optimal

sample size for estimating bare ground with point transects.

Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky

Mountain Research Station, Forestry Sciences Laboratory.

Shiflet, Tomas N. (ed). 1994. Rangeland cover types of the United

States. Denver, CO: Society for Range Management. 152 p.

U.S. Department of Agriculture, Forest Service. 2001. Forest survey

field procedures. Unpublished field guide on file at Ogden, UT:

U.S. Department of Agriculture, Forest Service, Rocky Mountain

Research Station, Forestry Sciences Laboratory, Interior West

Forest Inventory and Analysis Program.

U.S. Department of Agriculture, Forest Service. 1998. Forest survey

field procedures. Unpublished field guide on file at Ogden, UT:

U.S. Department of Agriculture, Forest Service, Rocky Mountain

Research Station, Forestry Sciences Laboratory, Interior West

Forest Inventory and Analysis Program.

U.S. Department of Agriculture, Forest Service. 1996. Properly

functioning condition process. Report on file at Ogden, UT: U.S.

Department of Agriculture, Forest Service, Intermountain Region. 76 p.

U.S. Department of the Interior, Bureau of Land Management.

2000. Interpreting indicators of rangeland health, version 3.

Technical Reference 1734-6. Denver, CO: U.S. Department of the

Interior, Bureau of Land Management Service Center. 118 p.

Winward, Alma. 2000. Monitoring the vegetation resources in

riparian areas. Gen. Tech. Rep. RM-47. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research

Station. 49 p.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-104. 2003 11

Scientific name Common name

Acroptilon repens Russian knapweed

Ambrosia tomentosa Skeletonleaf bursage

Arctium minus Common burdock

Cardaria draba Pepperweed whitetop

Carduus acanthoides Plumeless thistle

Carduus nutans Musk thistle

Centaurea biebersteinii Spotted knapweed

Centaurea diffusa Diffuse knapweed

Cirsium arvense Canada thistle

Convolvulus arvensis Field bindweed

Cynoglossum officinale Houndstongue

Elytrigia repens var. repens Quackgrass

Euphorbia esula Leafy spurge

Isatis tinctoria Dyer’s woad

Lepidium latifolium Perennial pepperweed

Leucanthemum vulgare Oxeye daisy

Linaria dalmatica Dalmation toadflax

Linaria vulgaris Toadflax

Lythrum salicaria Purple loosestrife

Onopordum acanthium Scotch thistle

Sonchus arvensis Perennial sowthistle

* Hypericum perforatum St. Johnswort

*A new invader in the State but not yet listed as noxious in Wyoming.

Appendix A—Plant species designated as noxious weeds in Wyoming
12 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-104. 2003

Appendix B—References for ground cover criteria for threshold watershed

protection in the Intermountain West as it relates to properly functioning

condition for rangeland health ______________________________________

Goodrich, Sherel. 1997. Personal communication. Desired future

condition and potential natural community—descriptive input in

Ashley National Forest allotment planning processes, and range

trend data sheets for various sites. Vernal, UT: U.S. Department

of Agriculture, Forest Service, Ashley National Forest.

Johnson, Curtis M.; Elsbernd, Van C. 1997. Memorandum to the

Washington Office on the National Rangeland Inventory. On file

at Ogden, UT: U.S. Department of Agriculture, Forest Service,

Intermountain Region. 12 p.

Lewis, Mont E. 1970. Alpine rangelands of the Uinta Mountains,

Ashley and Wasatch National Forests. Misc. Pub. Ogden, UT:

U.S. Department of Agriculture, Forest Service, Intermountain

Region. 75 p.

Muegglar, W.F.; Stewart, W.L. 1980. Grassland and shrubland

habitat types of western Montana. Gen. Tech. Rep. INT-66.

Ogden, UT: U.S. Department of Agriculture, Forest Service,

Intermountain Research Station. 154 p.

Nelson, Lynda P.; Jensen, Mark P. 1987. Sagebrush-grass community types of the Humboldt National Forest. Misc. Pub. Ogden,

UT: U.S. Department of Agriculture, Forest Service, Intermountain Region. 80 p.

O’Brien, Renee A. 1997. Personal communication. FIA ground cover

summaries for the Ashley National Forest. Ogden, UT: U.S.

Department of Agriculture, Forest Service, Rocky Mountain

Research Station.

Society for Range Management. 1994. Rangeland cover types of the

United States. Thomas N. Shiflet, editor. Denver, CO: Society for

Range Management. 152 p.

Tart, Dave. 1996. Big sagebrush plant associations of the Pinedale

Ranger District. Misc. Pub. Pinedale, WY: U.S. Department of

Agriculture, Forest Service, Bridger-Teton National Forest. 97 p.

Tart, Dave. 1997. Personal communication. Ground cover data from

the Bridger East ecological unit inventory database. Pinedale,

WY: U.S. Department of Agriculture, Forest Service, BridgerTeton National Forest.

Tew, Ron K.; Lott, John T.; Bliss, Timothy M. 1988. Ecosystem

stratification of the Fishlake National Forest. Misc. Pub. Ogden,

UT: U.S. Department of Agriculture, Forest Service, Intermountain Region. 176 p.

U.S. Department of Agriculture, Forest Service. 1967. Forest and

range hydrology handbook. Agric. Handb. 2536. Washington, DC:

U.S. Department of Agriculture, Forest Service. 272 p.

U.S. Department of Agriculture, Forest Service. 1996. Ecological

type potential natural community scorecards for Intermountain

and Rocky Mountain Region community types. Forest Service.

On file at Ogden, UT: U.S. Department of Agriculture, Forest

Service, Intermountain Region.

U.S. Department of Agriculture, Forest Service. 1996. Properly

functioning condition process. Report on file at Ogden, UT: U.S.

Department of Agriculture, Forest Service, Intermountain Region. 76 p.

U.S. Department of Agriculture, Forest Service, 1997. A hierarchical stratification of ecosystems for the Caribou National Forest.

Misc. Pub. On file at Idaho Falls, ID: U.S. Department of Agriculture, Forest Service, Caribou National Forest. 92 p.

U.S. Department of Agriculture, Soil Conservation Service. 1982.

Relationship between soil, plant community, and climate on

rangelands of the Intermountain West. Tech. Bull. 1669. Washington DC: U.S. Department of Agriculture, Soil Conservation

Service. 123 p.

Weixelman, Dave. 1997. Personal communication. Ground cover

data from the Humboldt-Toyiabe ecology team database. Sparks,

NV: U.S. Department of Agriculture, Forest Service, HumboldtToyiabe National Forest.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-104. 2003 13

Appendix C—Plants needed with at least 5 percent canopy cover in each

Society for Range Management cover type to be at potential natural

community ecological status _______________________________________

SRM cover type Predominant associated species

Alpine Geum rossi – Ross avens

Carex scirpoidea – Canada single-spike sedge

Carex elynoides – blackroot sedge

Festuca ovina – Sheep Fescue

Deschampsia cespitosa – Tuffed hairgrass

Danthonia intermedia – Timber oatgrass

Aspen Symphoricarpos oreophilis – Wolfberry

Juniperus communis – Common juniper

Sheperdia canadensis – Soapberry

Thalictrum fendleri – Fendler meadowrue

Geranium viscosissium – Sticky geranium

Lupinus argenteus – Silvery lupine

Lathyrus spp. – Sweetpea

Calamagrostis rubescens – Pinegrass

Elymus carinatuss – Mountain brome

Carex geyeri – Elk sedge

Trisetum spicatum – Spike trisetum

Tall Forb Geranium viscossimumi – Sticky geranium

Ligusticum filicnum – Fernleaf ligusticum

Helianthella uniflora – Single flowered sunflower

Valeriana edulis – Tobacco root

Bromus carinatus – Mountain brome

Mountain Big Sagebrush Artemisia tridentate var. vaseyana – Mountain big sagebrush

Symphoricarpos oreophilis – Wolfberry

Purshia tridentate – Bitterbrush

Elymus trachycaulus – Slender wheatgrass

Festuca idahoensis – Idaho fescue

Elymus spicatus – Bluebunch wheatgrass

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