Plant Species of Concern
and Plant Associations

of

Powder River County,

Montana

Prepared for tlie
Bureau of Land Management

by

Bonnie Heidel, Catherine Jean
and Susan Crispin

Montana Natural Heritage Piogram

Natural Resource Information System
Montana State Library

October 2002

MONTANA

Natural Heritage
Program

Plant Species of Concern
and Plant Associations

of

Powder River County,

Montana

Prepared for the

Bureau of Land Management

Miles City, Montana

Under Agreement #
1422E930A960015

by

Bonnie Heidel^Catlierine Jean

and Susan Crispin

Montana Natural Heritage Progiam

1515 East Sixth Avenue

Helena, Montana 59620-1800

MONTANA

Natural Heritage
Program

T&ltate nJ4^ Natural Resource

Library ^^Sr^ information System

© 2002 Montana Natural Heritage Program

P.O. BOX201S00 • 1515 East Sixtb Ave • Helena, MT_^9<520-1800

This document should be cited as follows:

Heidel, B., C. Jean and S. Crispin. 2002. Plant Species of Concern and Plant Associations of
Powder River County, Montana. Report to the Biueau of Land Management. Montana Natural
Heritage Progiam, Helena, Montana. 23 pp. plus appendices.

EXECUTIVE SUMMARY

Soutlieastem Montana, including Powder River County, has some of the most extensive range land-
scapes in tlie state. A long histoiy of ranching as tlie predominant land use and effective land steward-
ship have maintained or restored extensive areas that support good quality rangelands with healthy, di-
vei'se populations of native wildlife and high ecological integrity. However, tlie biological character and
richness of tliis region has not been well documented. The goal of this project was to survey Bureau of
Land Management (BLM) lands in Powder River County for plant species of concern and document tlie
natural vegetation on tliese lands, including communities of limited range and outstanding examples of
more widespread community types.

Our survey work emphasized major blocks of land administeied by the BLM, but also included odier
public lands near or continuous with BLM blocks. We visited most BLM tiacts of at least five contigu-
ous sections, as well as select scattered tiacts, and adjacent private lands with landowner permission.
We occasionally also surveyed on nearby state lands tliatwere part of BLM allotments.

Sui'veys were conducted in the summeis of 1999 and 2000. To document vegetation communities, we
sampled a broad range of habitat types tliroughout tlie geographic breadth of BLM-administered lands in
the county. Surveys ranged from the most rugged topography to flat lands and from tlie most heavily
wooded to the least vegetated. We focused more detailed data collection on excellent representative ar-
eas of common vegetation types, those types of limited distiibution and/or potential statewide or range-
wide significance, and types not previously known or documented to occur in soutlieastem Montana. In
surveying plant species of concern, we particularly emphasized species of global or range-wide signifi-
cance.

All new data on plant species of concern and vegetation communities were geo-referenced, digitized and
entered into tlie Montana Natural Heritage Program (MTNHP) data system, making diem readily avail-
able to tlie BLM, as well as othei' landowners, resource managers and decision-makers, both public and
private.

The results of these surveys doubled (from 5 to 10) the number of Montana plant species of concern
documented in the County. Based on tlie number of new populations discovered, one species has been
dropped from the Montana Species of Concern list, anotlier is recommended for possible downgrading,
and we recommend that four species be considered for removal from BLM "Watch' status.

We also documented a total of 46 native vegetation types in Powder River County. Several of these are
particularly well -rep resented or of significance on BLM lands, either because of tlieir extent and good
condition and/or because tliey represent types that are uncommon or range-limited. In addition to col-
lecting data from vegetation plots to better document and understand these communities, we also identi-
fied six notable areas where one or more were particularly well -rep resented in good or excellent condi-
tion, witliin ecologically intact landscapes.

While tliis study added a great deal to knowledge of tlie vegetation and ecology of Powder River
County, it is far from comprehensive. We would recommend tliat inventory work be expanded to in-
clude fauna as well as flora, and to encompass lands under other ownerships to gain a more complete
and accuiate frame of reference for understanding tlie biological resources and ecology of tliis remarka-
bly healtliy and intact native landscape.

ACKNOWLEDGEMENTS

For suggesting and initially facilitating this study, we are indebted to Hal Vosen, Range Conservationist
now retired from the Bureau of Land Management (BLM), Miles City Office. We also received valu-
able support and assistance during tlie project from staff of the BLM Miles City Field Office, and from
Bill Volk and Roxanne Falise of the Montana State Office.

A number of HeiitageProgiam staff contributed to production of this report. Cedion Jones and Duane
Lund designed and produced tlie maps; Martin Miller, Terrie Kenney, Joy Lewis, and Coburn Cunier,
helped witli data processing and production, and Steve Cooper contributed to final editing.

This report has benefited from tlie support and contributions of many people, however any errors of
commission or omission rest with tlie authors. This project was supported by a challenge cost-share
agieement between tlie Bureau of Land Management and tlie Montana Natural Heritage Program (BLM
Agieement Number 1422E930A960015, Task Orders # 26 & 31).

TABLE OF CONTENTS

Executive Summary i

Acknowledgements ii

Table of Contents iii

Intioduction 1

SUidy Area 2

Location 2

Climate 2

Geology and Soils 3

Elso-Midway-Tliurlow association 4

Ringling-C abba-Midway association 5

Els o-Remmit-Ocean Lake association 5

Kyle-Midway -Cabb a association 5

Halverson-Glenberg association 5

Metliods 6

Inventory 6

Data Management 9

Vegetation Analysis 9

Results and Conclusions 12

Plant Species of Concern 12

Astragalus barrii 14

Care X gravida 14

Ceanothiis herbaceous 14

Chenopodhim siibg^abrum 14

Cypenis schMeht/tzii 15

Dichanthelium oligosanthes var. scribneriaimm 15

Mentzeha nuda 15

FlUox atidicola 15

Physaria brassicoides 15

Psoralen hypogaea 16

Vegetation Commuiuties 16

Pascopynmi smithii — Hesperstipa contata 16

Pascopyrum smithii — Biichloe dactyioides 16

Calamordfa longifoha — Hesperostipa comata 17

Andropogon hallii — CalaiHorilfa fotigifolia 17

Andropogon JtalUi — Carex inops ssp. heliophila 18

Psetidoroegneria spicaia — Boutefoua curtipe/tdula 18

Artemisia tr/derttata s^p. wyommgef/sis — Pascopyrum simthii 18

Artemisia tridentata ssp. wyomingensis — Buchloe dactyioides 19

Pimts po/tderosa — Pseudoregneria spicaia 19

Juniperus scopiilorum — Piptaiherum micranthum 19

Recommendations 20

Literature Cited 21

111

FIGURES

Figure 1. Topography of Powder River County
Figure 2. Powder River County Study Area
Figure 3. Climate Diagram of Broadus, MT
Figure 4. Elso-Midway-Thurlow association setting
Figure 5. Ringling-Cabba-Midway association setting
Figure 6. Elso-Remmit-Ocean Lake association setting
Figure 7. Kyle-Midway-Cabba association setting
Figure 8. Halverson-Glenbeig association setting
Figure 9. Vegetation study plots in Powder River County
Figure 10. Plant species of concern in Powder River County

TABLES

Table!. Plant Inventory Targets

Table 2. Plant Synonymy

Table 3. Plant Associations in Powder River County

Table 4. Plant Species of Concern in Powder River County

APPENDICES

Appendix A. Global/State Rank Definitions

Appendix B. Site Descriptions

Appendix C. Powder River County Plant Species of Concern

Appendix D. Rangeland ecological sites and plant associations of Powder River County

Appendix E. Plant Community Descriptions

IV

Photo by Bonnie Heidel

INTRODUCTION

Southeastern Montana, including Powder
River County, has some of tlie most ex-
tensive range landscapes in the state. A
long history of ranching as tlie predomi-
nant land use and effective land steward-
ship have maintained or restored exten-
sive areas that siippoit good quahty
rangelands with healtliy, diverse popula-
tions of native wildlife and high ecologi-
cal integrity.

However, the biological character and
richness of diis region has not been well
documented. Recent studies focusing on
the Tongue River drainage in southeast-
em Rosebud County (Heidel 1997) and
Carter County (Vanderhorst et al. 1998)

have provided a gieat deal of new infonnation on the vegetation and rare flora, but neither extended to
Powder River County. This study was undertaken as a first step in documenting the county's biological
resources and ecology, in tlie context of soutli eastern Montana and tlie sun'ounding region.

Our goal was to suivey BLM lands in Powder River County for plant species of concern and document
tlie natural vegetation on these lands, including communities of limited range and outstanding examples
of more widespread community types. Sui'vey work emphasized major blocks of land administered by
the Bureau of Land Management (BLM), but also included otiier public lands near or continuous with
BLM blocks.

^'Species of concern" are those identified by tlie Montana Natiual Heritage Program (Heidel, 2001) as
vulnerable to extirpation across tlieir range or in Montana because of rarity, significant loss of habitat,
and/or sensitivity to habitat disturbances. Most of tliese are also designated as BLM Special Status Spe-
cies. We placed particular emphasis on species Ihat are of global orrangewide concern (Heritage ranks
Gl -G3; see Appendix A for rank definitions). In tlie course of sui'vey work, we also documented loca-
tions for "species of potential concern" (fomierly called "*watch" species) -primarily species of uncer-
tain status or regional endemics that are thought to be secure witliin their limited range.

Our specific objectives were to:

Clarify the distribution and status of plant species and vegetation community types relative to BLM

lands;

Identify particularly significant populations, habitats and areas of natural vegetation on public lands

in Powder River County;

Highlight management opportunities for maintaining species of concern and significant vegetation

communities;

Consolidate new and previous infoiTnation as a reference for tlie Bureau of Land Management and

otliers.

STUDY AREA

Figure 1. Topography of Powder River County

Location

Powder River County covers 3,297 square
miles of unglaciated Missouri Plateau in die
Eastern Sedimentary Plains of southeast Mon-
tana. The Powder River aud its tributaries,
including Little Powder River, Mizpah Creek
and Pumpkin Creek, drain most of tlie county,
dissecting the uplands and underlying sedi-
mentaiy bedrock layeis. Ottei' Creek and Bea- ^>'^
ver Creek, tributaries of the Tongue River,
drain the west end of the county. Nortli-soutli
valleys and intei'vening ridges fonn the preva-
lent landfomis (Figure 1), spanning elevations
from 2,768 feet in tlie county's northwest cor-
nel' to 4,305 feet in die soutliwest comer
(Parker etal. 1971).

Powder River County was part of Custer County until 1919. The county seat, Broadus, lies at tlie junc-
tion of tlie county's two main highways, M-59 and US-212. Lands in tlie county weie settled for ranch-
ing, and beef production reached its peak between 1880 - 1920 when open range prevailed (Parker et ak
1971). Cattle ranching remains tlie first and foremost industry the county today.

Like other counties in tliis area, the prevailing land cover is rangeland, however it includes a relatively
high woodland component. In 1976, land cover in Powder River County was 84% rangeland, 10%
woodland, and 5% cropland (Ross and Hunter 1976).

The highest ridge systems and the most extensive pine woodlands lie witliin the Ashland District of Cus-
ter National Forest at the western end of tlie County, diough tliere are pine-covered escarpments and
knolls in the soutlieastem comer and widely scattered tliroughout the County. Lands administei ed by
the BLM are concentrated on, but not limited to, rough teirain along the Powder and Little Powder Riv-
ers (Figure 2), and are intenningled witli private and state lands.

Climate

The area's climate is continental and typical of tlie high plains, witli cold winters, warm summers, and
peak rainfall early in tlie growing season. Average annual precipitation at Broadus is 13.4 inches while
across tlie county averages range from 11-19 inches. The average of meanmondily temperatures is 7.3°
Celsius (45.1" Fahrenlieit), with summei' temperatures usually cooler tlian in tlie Yellowstone River val-
ley to the north (Parkei' et al. 1971). Precipitation is typically concentjated in May and June, and maxi-
mum mean monthly temperatures occur later in July, resulting in a late summer water deficit (Figure 3).
Compiled climate data invariably mask tlie high degree of variation in climate from year-to-year, moiitli-
to-month, and tlie great variations tliat occur even in the span of weeks, days and hours.

Figure 2. Powder River County Sliidy Area

BLM

USPS

State trust fands

Tribal & Allotted

Other private

Water

10

Scale in Miles
MTNHP April 20, 2001

Geology and Soils

The sweeping, luiglaciated landscape of Powder River County is carved by erosion largely from the Fort
Union Fomiation, a heterogeneous Paleocene sedimentaiy deposit made up of sandstone, shale, ben-
tonite, lignite and otlier materials. It is dissected by Quaternary alluvial deposits along major rivers and
tributaries. The county lies entiiely widiin tlie unglaciated segment of the Great Plains biogeographic
province, and largely within the Powder River Basin section. Along tlie eastern side of the county, tlie
Foit Union fomiation gives way to shales and claystones of tlie Piene Shale Plains section.

Soils tluoughout die county are entisols and aridisols (Torriorthents and Camborthids) of dissected to
nearly level sedimentaiy bedrock plains and hills. In addition, Ustorthents and Argiborolls occur in the
pinelands, and Toniflu vents, Torrioitlients and Camboitliids in die broadest river valleys (Montague et
al. 1982). It is easiest to visualize tlie terrain and associated soils tluough schematic diagrams. The rela-

Figure 3. Climate diagram showing average montlily temperature and precipitation for Broadus, MT.
(Gray portion of bar indicates growing seasoQ lengthy or the number of frost- fi:ee days with mean daily minimum
temperature above 0° Centigrade.)

Broadus, MT {924 m/3030 ft) {7.3 C/45.1 F) (350.0 mm/1 3.8 in) (1 948 -1999)

40 n

f^n

ou

35

—•—Temperature

30

—A— Precipitation

-

-60

25

/ \ Period of

„ 20-
u

"^ 15-

"S 10-
m

E 5-
<u

-

/ -h\^^ — •^relative drought

-

Precipitation (mm)

-5-

^^^^

N

»

i

-10-
-15-
-20

-

-20

r- m

: 1 ii

^n

1 1 1 1 1 1 1 1 1 1

-H-U

Je

n Feb Mar Apr May Jun Jul Aug Sep Oct Nov

Dec

tionships between topogiaphy and soils for five of the nine major soil associations in tlie County are pre-
sented in Figures 4-8, from Parker et al. (1971). These were tlie primaiy associations in BLM lands that
we surveyed, and are listed below in descendmg order of tlieir prevalence on diose lands.

Figure 4. Elso-Midway-Thurlow association setting

Elso-Midway-Thurlow association

Dissected plains along the Powder and Little
Powder Rivers are mainly calcareous silt loams
and silty clay loams of tlie Elso-Midway-
Thurlow association (Figure 4). Deep-soil con-
ditions are more extensive witliin tiie gentler 8-
35% range of slopes, compared to tlie 35-75%
range of slopes. This association comprises a
disproportionately high share of BLM lands,
about 28% of the county according to Parker et
al. (1971). Silty ecological sites of die Elso
series prevail in the dissected uplands, whereas
the Midway series is associated with shallow
clay and silt ecological sites on ridges and knolls. The bare Midway outcrops and gully erosion make it
appear more dissected from the air (Figure 4) tlian it does from the ground.

Rmgling-C»bba-Midw»y association

Irregularly sloping and hilly tenain at higher
elevations in tlie comity are made up of silty
loams to clay loams (Figure 5). Ringling soils
prevail and cap the uplands witli erosion-
resistant baked porcellanite shale, representing
a shallow ecological site. Cabba soils are me-
dium-textured shallow soils. This association
covei's about 45% of the county according to
Parker et al. (1971) and is distiibuted over
much of tlie western half

Figure 6. Elso-Reinmit-Ocean Lake association setting

Figure 5. Ringling-C abba-Midway association setting

Elso-Remmit-Ocean Lake association
Smootli, rounded hills and sparingly dissected
plains are made up of sandy loams and shallow
silt loams at the far eastern end of the county
(Figuie 6). Silty ecological sites of die Elso
association prevail in parts of the gentle up-
lands, while sandy ecological sites of tlie Rem-
mit and Ocean Lake series are also tliroughout
the uplands.

Kyle-Midway-Cabba associ»tion

Hilly, rounded relief in die far soutliwestem
corner of the county has deep soils that are
clayey throughout (Figure 7). This association
resembles tlie Ringling-Cabba-Midway asso-
ciation (preceding) except for tlie prevalence of
the Kyle series, resulting in more rolling than
dissected tenain.

Figure 7. Kyle-Midway-Cabba association settin

Figure 8. Halverson-Glenberg association setting

Halverson-Glenberg association

Valley bottoms and stieani terraces have deep
loams soils deiived from alluvium (Figure 8).
These low-lying areas and their gentle terrain
are found along all of tlie rivers as well as most
of the major creeks, (tliose labeled on the BLM
1:100,000 map seiies).

METHODS

Surveys were conducted in tlie summers of 1999 and 2000. During tlie first year of fieldwork, we fo-
cused on targeted sui'veys for species of concern (Table 1) and priority vegetation types. During 2000,
we more tlioroughly dociunented plant associations in the largest blocks of BLM-adininistered lands.

We began by compiling and reviewing existing data on species of concern and vegetation for Powder
Rivei' County, as well as adjacent counties and states. This infomiation was used to target areas of po-
tential habitat for species of concern and to identify tlie range of native vegetation types documented.

Infomiation sources for vegetation and flora included Taylor and Hoist (1976), Culwell (1979), Husby et
al. (1979), Hansen and Hoffman (198S) and Vanderhorst et al. (1998), in addition to unpublished work-
ing lists of plant associations for the region, and data assembled and rapid ecological assessments con-
ducted for The Nature Conservancy's Nortlieiii Gieat Plains Steppe Ecoregion Plan (The Nature Conser-
vancy 1999). The two studies on die Ashland Disti'ict of Custer National Forest (Taylor and Hoist 1976,
Hansen and Hoffman 1988) were the only readily available references on the county's vegetation, hi
addition to tliese reports, we drew on vegetation infomiation from studies in adjoining states and prov-
inces, and from the recently compiled state and regional National Vegetation Classification System
(NVCS) for Gieat Plains states (NatureSei-ve 2002, Faber-Langendoen 1999).

Othei^ useful infomiation sources included the Powder Rivei' County Area soils survey (Parker et al.
1971), a Natural Resource Conservation Semce (NRCS) field review of mapping units (1980). We also
consulted BLM color aerial photographs to assess characteiistics of BLM tjacts and to help identify ar-
eas of potential habitat for target species. Notes were transcribed onto U.S.G.S. topographic maps (7.5')
for reference in the field.

From tlie MTNHP databases, we identified plant species of concern with documented occurrences in the
county and compiled available infomiation on tlieir biology and habitat characteristics. Some occur-
rences were targeted for re-visits to fill data gaps on tlie extent of populations, exact locations, or habitat.
We also drew on findings from previous botanical suiveys in the region (Heidel and Dueholm 1995,
Heidel andMamott 1996, Vanderhorst et al. 1998) to identify species of concern tliat may potentially
occur in Powder River County. Based on tliis infomiation, we developed an expanded list of target spe-
cies for our inventories (Table 1).

Field Surveys

Surveys were focused on tlie largest blocks of BLM -administered lands. We visited most BLM tracts of
at least five contiguous sections, as well as select scattered tiacts, and adjacent private lands with land-
ownei' permission. We occasionally also surveyed on nearby state lands that were part of BLM allot-
ments.

We documented occurrences for species of concem by collecting observational data on biology, habitat,
population size and possible trends. Locations of rare plants were mapped on 7.5' topographic quads.

Vouchers specimens were collected if population numbers were sufficiently large to avoid impact
(Montana Native Plant Society 1993). We also kept a miming list of tlie species encountered, cross-
referencing tliis with county dot maps in two floristic references (Bootli and Wright 1966, Great Plains
Flora Association 1977), and witli the geneial distributions described in Dom's flora of Montana (1984),
and flora of Wyoming (Dom 1992), tlie distiibution data in tlie Wyoming Rare Plant Field Guide (Fertig
et al. 1994) and the Wyoming plant distiibution atlas (http:/Avww.esb. utexas.edu/tcliumley/wyomap/
atlas.htm).

Table 1. Inventory Targets for Plant Species of Concern

Global State

Scientific N»iue

Common Name

Rank

Rank Phenology J

Species of Concern

iinorpha ccmescens

Leadplant

G5

SH

July

isclepias stenophylla

NaiTowleaf milkweed

G4G5

SI

late June- July

istragalus barri

Ban's mi Ik vetch

G3

S3

May -early June

istragalus racemosus var. racemosiis

Ra c em e m i Ik v et ch

G5T5

S2

July

Carex grmida var. grcnida

Pregnant sedge

G5T5?

SI

late June- July

Ce a/to thus herbaceous

New Jersey tea

G5

SH

late June

Che/topodium subglabrum

Smooth goosefoot

G3G4

SI

July

Cyperus acuminatus

S h or t -p inte d fl ats e dg e

G5

SI

July -Aug

Dichanthehum ohgoscmibes var. scribneriatmm

Scribner's panic grass

G5T5

SI

late June- July

Eriogonum visheri

Visher's buckwheat

G3

SI

July

MentzeUa imda

Dwaif mentzelia

G5

SI

July

PhJox andicola

Plains phlox

G4

S2

May -June

Pity sari a brassicoides

Double bladdeipod

G5

S2

May -June

Physaria didymocarpa var, lanata

Woolly bladderpod

G5T2

SI

Psilocarphus brexissimus var. brevissimus

Dwaifwooly -heads

G5T?

S2

late June- July

Scirpus fteterochaetus

Slender bulnish

G5

SI

July

Sporoboh/s asper

L ongl e af diop seed

G5

SH

July

Species of Potential Concern

igastac he foe idc ulum

Lavender hyssop

G5?

SA?

July

Carex torreyi

Torrey's sedge

G4

S3

July

Echinacea angustifolia

Purple coneflower

G4

SU

June- July

Exax prolifera

Big -head evax

G5

SU

June

Geum canadense

White avens

G5

SU

June

Ipomopsis congesta ssp. pseudotypica

Wyoming ipomopsis

G5T3?

S2S3

May -June

Psoralea hvpogaea

Little indian breadroot

G5T4

S2S3

May -June

During the first year of vegetation surveys, we sampled a broad range of habitat types throughout the
geographic breadtli of ELM -administered lands in the county. Surveys ranged from tlie most nigged to-
pography to flat lands and from die most heavily wooded to tlie least vegetated. Survey results were
compared against documented Montana plant associations to identify uncommon or previously undocu-
mented types.

Based on results from the fiist year of surveys, we designed vegetation surveys in 2000 to characterize:
L Excellent representative areas of common plant associations,

2. Plant associations of potential statewide oi rangewide rarity and significance, and

3. Provisional new plant associations or those not previously known fiom soudieastem Montana.

We could not sample all plant associations in each area surveyed, but ratlier focused on tlie more distinc-
tive types and those meeting the criteria listed above. This approach made it possible to collect a
broader range of infonnation relatively quickly, while focusing more detailed data collection on tlie
more important or distinctive vegetation features in the study area.

Plant associations were identified and documented based on species composition, stmcture and abiotic
environmental characteristics. Vegetation data was collected within representative 1/10 acre plots (37.2
ft radius) and recorded on a standardized survey foiin. Vegetation plots were placed to sample homoge-
neous natural vegetation and unifomi environmental conditions across tlie plot, in areas of least distur-
bance (Figure 9). Soil texture was recorded and used to characterize the ecological site. All species pre-
sent were recorded with canopy cover values.

Our surveys focused on grassland types for several reasons. Grasslands represent well over 90% of the
existing natural vegetation on BLM lands, and are among tlie most distinguishing ecological features of
the county, in a statewide context, hi addition, grasslands of this area provide a missing link in piecing
togetlier vegetation classifications of adjoining aieas.

Figure 9. Vegetation sampling plots in Powder River County

.:?^^

10 Milec

tiV, 4U 3DD^ trlnhiailHi rrl la

A Plot location

BLM

USPS
_ Tribal
B state Trust

Other private

Water

Our principle floristic references weie the Great Plains Flora (1977, 1986), Dorn (1984), and Hitchcock
and Cronquist (1973). Plant nomenclature follows Kartesz (1999), which uses newly revised names for
the wheat-grass tribe (Ehmtis and Agropyron), replacing the more familiar scientific names that have
long been in general use. Thus western wheatgrass, which is referenced as Agropyron simthii in Booth
(1950) and Hitchcock and Cronquist (1973) and Ehinus smithii inDom (1984), is now treated as as
Pascopyrum smithii. Table 2 provides a cross-reference for synonymy of dominant and indicator spe-
cies that appear in our plant association names. We also reference each species by both scientific and
common name when first mentioned in this report. Common names are based primarily on a national
list developed by the Natural Resource Consei'vation Service (2001). To a lesser degree, we use com-
mon names cited by Region 1 of tlie U. S. Forest Service.

Data Management

New data collected on plant species of concern and high quality vegetation communities were geo-
referenced, digitized and documented as element occuirence records in the data system of tlie Montana
Natuial Heritage Program. Specimens have been deposited at tlie University of Montana (MONTU).
Plot data and summary infoimation on noteworthy sites weie also tianscribed to a computerized fomiat
for pemianent storage in tlie MTNHP databases. This data system serves as the state's clearinghouse
and as a primaiy source of information on tlie status and distribution of Montana's native species and
habitats.

Vegetation Analysis

We analyzed vegetation data to identify plant associations consistent widi the National Vegetation Clas-
sification System (Grossman et al. 1998). This classification uses recurring vegetation attributes, em-
phasizes natural existing conditions, and can be used to identify vegetation units based on botli quantita-
tive and, in some cases, qualitative data. The NVCS is hieiarchical and combines floristics at the lowest
levels (associations and alliances) and structure (physiognomy) and overarching climate conditions at
the highest levels. Plant associations are defined by dominant species of the uppennost vegetation layer
and any co-dominant species, diagnostic species, or the dominant species of understoiy vegetation lay-
ei's.

We developed a preliminaiy cross-reference (see Appendix D) between NRCS rangeland ecological
sites and plant associations tracked by tlie Montana Natural Heritage Program. Some plant associations
have wide ecological amplitude and occur across a range of ecological sites. For GxmuplG, Artemisia
tr'fdentata spp. }]yoimngemis / Pascopyrwn smithii can be found on thin silty, very shallow to clayey
ecological sites, wheieas^^n/j/^jc confertifoha - Artemisia tridentata is found only on the shale ecologi-
cal site.

Table 2. Synonymy of scientific names for indicator and characteristic plant species (alphabetically ar-

nd

ranged in 2 column).

Common Name

In: Booth (IPSO), (1966) or

Great Plains Flora Assoc.

(1P86)

In:Dom(19S4)

In: Kai'tesz & Meacham
(1999)

rhickspike Wheatgrass

Agropyron dasy^stachyiirii

SlyriJHS lanceolatiis

Elymus lanceolatus

Bearded Wlieatgrass

Agropyron camnum

Elymus trachycaulus

Elymus trachycaulus

[utermediate Wlieat-
grass

Agropyron internieduira

ElyriJHS hispidiLS

Thinopyrum intermedium

Western Wlieatgrass

Agropyron snuthu

Elymus smithu

Pascopyrum smithu

Bluebiincli Wlieatgrass

Agropyron spicatnra

Elymus sptcatus

Pseudoroegnena spicata

Redtop

Agrostis stolomfera

Agrostis stolontfera

Agrostis gigantea

Creeping Bentgrass

Agrostis alba vnv.Agroshs

Agrostis stolontfera

Agrostis stolonifera

Little Blue stem

Andropogon ^coparius

Sciuzachynuni scoparium

Schizachyrium scoparium

Gardneri's Saltsage

Atrip lex nuttaUii

Atriplex gardneri

Atriplex gardneri

Rill scale

Atrip lex dioica

Atriplex suckleyi

Endolepis dioica

Needleleaf Sedge

Carex eleochans

Carex stenophylla

Carex dunuscula

Sun Sedge

Carex heliophtla

Ca rex pe nsy Iva mca

Carex mops ssp. heliophila

Woolly Sedge

Carex lanuginosa

Carex lanuginosa

Carex pellita

Rubber Rabbi thru sli

Chrysothamnus nauseosus

Chrysothamnus nauseosus

Ericameria nauseosa

Rifted Hairgrass

De^^champsia cespitosa

Desciiarapsia cespitosa

Deschampsia cespitosa

[iiland Saltgrass

Distichlis sptcata var. striata

pistichlis stncta

Distichlis spicata

Few-headed Spikerush

Eleochans paiiciflora

Eleocharis paucijlora

Eleocharis quinueflora

Giant Wildrye

Elymus anereus

Elymus cinereiis

E'ymus cinereus

Prairie Junegrass

Ko e le ria py rami da ta

Koeleria macrantha

Koeleria macrantha

[udian Rice gra^s

Oiyzopsis hymenoides

Oiyzopsis hymenoides

Achnatherum hynienoides

Littleseed Ricegrass

Oryzopsis micrantha

Oiyzopsis micrantha

Piptatheruni micranthunj

Sandberg Bhiegrass

Poa sandbergii

Poa secunda

Poa secunda

Black Cottonwood

n/a

Populus balsamifera

Populus balsamifera ssp.
'inchocarpa

Shnibby Ciuqiiefoil

Po te ntillafi 'utt co sa

Po te n tilla fruti c osa

Dasiphora fruticosa ssp.
^!0}'ibunda

Silver-leaved Sciirfpea

Psoralea incana

Psoralea argophylla

Pediomelum argophyllum

Lemon Scurfpea

Psoralea lanceolate

Psoralea lane eo lata

Psoralidium lanceolatum

Hardstem Bulrush

Scirpiis acutns

Scirpus acutus

Schoenoplectus acutus

Needl e-and-tlirea d

Stipa comata

Stipa comata

Hesperostipa comata

Northern Porcupine
Grass

Stipa cui'tiseta

Stipa spartea (implicit as S. s.
var. curtisetd)

Hesperostipa curtiseta

Green Needlegrass

Stipa vtridula

Stipa viridula

Nassella viridula

10

RESULTS AND CONCLUSIONS

Among die most ecologically significant characteiistics of BLM lands in Powder River County are the
extensive and largely intact range landscapes, especially those supporting a mosaic of western wheat-
grass and Wyoming big sagebrush vegetation. Botli grassland and sagebrush communities support di-
vei'se suites of native species, some of which have been identified as potentially declining or vulnerable
eithei' locally or regionally. Foitunately, all or nearly all of these species still tlirive in the large, ecologi-
cally intact range landscapes that exist in Powder River County and elsewhere in eastern Montana. Al-
though this survey did not focus on animal species, it did yield substantial new information on plant spe-
cies of concern, tlie diveisity of vegetation types in the county, and areas supporting particularly signifi-
cant species populations and/or vegetation communities.

Othei' featuies of ecological significance in the county are the extensive sandy ecological sites, wliich
appear as isolated but not uncommon areas of well-developed sandy habitat. These sites support many
plant species of limited regional distiibution or endemism tliat are Montana species of concern, and they
also support distinctive plant communities.

Plant Species of Concern

Our surveys identified 5 new species of concern in the county, bringing tlie total documented to 10
(listed in Table 3). All but one are designated as BLM ''Watch" species. Our surveys also generated
new locations for species of concern tliat were previously documented in tlie county. Perhaps the most
important findings were new locations for Astragalus barrii (Ban's milkvetch), expanding the total
known in the county to 23, including the largest population documented to date in Montana (see below).
Figure 10 shows all known locations for species of concern in the counly.

Table 3. Plant species of concern in Powder River County.

Records in

Rf cords in

Scientillc Name

Common Name

Global/
State Rank BLM Status

Powder
River Co.

Montana
(total)

istragalus barrii

Ban's Milkvetch

G3/S3

Watch

23

32

Carex grcnida rar gravida

Pregnant Sedge

G5T5/S1

Watch

1

5

Ceatiothus herbaceus

New Jersey Tea

G5T? / SH

Watch

1

1

Che/topodium subglabnim

Smooth Goosefoot

G3G4/S1

Watch

1

5

Cyperus sckweinitzii

Schweinitz' Flatsedge

G5/S2

Watch

2

8

Dichanthelium oligoscmtfiesScribnGr'^ Panic Grass

G5T5/S1

Watch

4

6

var scribnerianum

Mentzelia imda

Bractless Mentzelia

G5/S1

Watch

3

8

Phlox andicola

Plains Phlox

G4/S2

Watch

1

10

Phy sarin brassic aides

Double Bladdeipod

G5/S2

3

8

Psoralea hypogaea

Little Indian BreadfniitG5T4 / S2S3Watch

6

18

11

Figure 10. Locations for Plant Species of Concern in Powder River County

,_^, NanjT^l Heritage rBr.'^',r^'"^

Hflf <«l-3£LD«r"|M<EB>l-lp rnri-

^ Astragalus barrij locations J

(W) Other tracked species '

I I Watch species (potential concern) Water

BLM
USPS
Tribal
State Trust
Other private

Infomiation gatliered during survey work has also provided new insights into tlie habitats characteristics
and ecology of tliese species. Below, we have summarized cunent infomiation for each species on tlieir
distribution in die county and potential management considerations. Appendix C provides fnll species
descriptions with additional infomiation, including detailed identification and habitat data, range-wide
distribution, an explanation of status, and illustrations and photos of each species.

Astragalus barrii, Harris milkvetch (G3, S3, BLM Watch status)

Coti/tty Distribution: The two largest areas of concenti'ation for tliis species in Montana lie in Powder
River County, where it has been documented from a total of 23 locations. Of tliose, 18 are clustered into
two large population complexes, one along part of Otter Creek and the other in the Little Powder River-
drainage. In visits to tlie latter, we found Ihat it occurs repeatedly across tlie landscape where suitable-
habitat is extensive, such that some of tlie populations are quite large.

12

Ecology and managemeni considerations: This species almost always occurs on secondary range and is
not glazed due to its low growth fomi. It is little-affected by allotment management practices and devel-
opments unless concenti'ated livestock tiampling occurs in its habitat. It may be vulneiable to exotic spe-
cies encroachment, however there is little tlireat from weedy annuals at present, and the fine texture and
instability of soils limit invasion by annual bromes. A non-native mustard, Malcolmia {Malcolmia qfri-
ca/td), is beginning to invade fine-textured slopes of Powdei' River County; it has become abundant in
similar habitats elsewhere, and appears to be spreading along backroads. Seeding of sweetclover
(MelHohts spp.) should be avoided in revegetation efforts or road plantings near tliis species' habitat.

Status Note: Bair's milkvetch is a regional endemic species of limited distribution in the nortliem Great
Plains, where it is restiicted to portions of thiee states. Its total range comprises an area less tlian half
the size of Montana. Given the extensive distribution of Ban's milkvetch in Powder River County, tlie
status of tliis species will be reviewed and may be downgraded statewide from ''species of concern" to
''species of potential concern." This evaluation will need to consider any cunent tlireats to tlie species
and tlie security of existing populations and habitats with respect to land management, especially for
those on public lands.

Carer gravida, Pregnant Sedge (G5, SI)

Coii/tty Distribution: It has only been found in two places on the Ashland District of the Custer National
Forest (Heidel and Marriott 1996), and these represent tlie known Powder River and Rosebud records. In
tlie course of tliis survey tliere was veiy little suitable habitat in tlie areas that were visited, so it was not
found and no additional data was collected on tliis species and its distribution.

Ecology and management considerations: This plant seems restricted to niesic microhabitats witliin
pine woodlands, which could make it vulnerable to changes in woodland structure and composition by
grazing and logging. These settings are also vulnerable to invasion of exotic species like Kentucky blue-
grass (Poapratensis). Theie were fire scars among the Ponderosa pine at one of the Ashland District
sites where it occuned, indicating tliat the species survives ground fires.

Status note: Since this species is restricted to woodlands and has not been found on BLM lands in Mon-
tana, it could be dropped from BLM ''Watch" status.

Ceanothus herbaceous^ New Jersey tea (G5, SH)

County Distribution: The single collection of this species in Montana was from a "grassy, pine-covered
hill" in Powder River County. There are few pine stands on BLM lands in tlie county, and of tlie few
that were surveyed, none appeared to have suitable microhabitat. It is not known whetlier tliis species is
resti'icted to pineland habitat in Montana, and we also looked for it nearby grassland habitat on BLM
lands. We did not locate it, and were unable to collect any additional data on this species in tlie county.

Ecology and management considerations: We have no infomiation on the ecology of tliis plant. It has
reportedly diminished elsewhere on the Great Plains (Ode, pers. conini.) Some species of Ceanothus are
highly palatable to wildlife and livestock.

Status note: Since this species is restricted to woodlands and has not been found on BLM lands in Mon-
tana, it could be dropped from BLM "Watch" status.

Chenopodiunt subglabrum, Smooth Goosefoot (G3G4, SI)

County Distribution: This plant was documented for die first time in Powder River County and on
BLM -administered lands during this study. We found it in the noitlieastem comer of the County on an
isolated ridgetop.

13

Ecology and management considerations: The Powder River County population occurs in secondary
range, where livestock use is light and watei' sources are remote. This species is a poor competitor and is
associated with otlier annuals and early-succession species. Maintenance of early successional habitat in
upland settings requires a balance of fire and/or grazing. Leafy spuige is in early stages of invading
some of the most extensive areas of tliis habitat type in the state.

Cyperus schweinitzii, Schweinitz' Flatsedge (G5, S2)

Coii/tty Distribution: We documented tliis plant for the first time in Powder Rivei' County, at two sites
in the noitlieastem comer in small blowouts at toeslope positions on loose sand eroded from sandstone
outcrops above.

Ecology and management considerations: The Powder River populations occur in primaiy range that is
in good to excellent condition. Maintaining the species' early -sue cession habitat requires grazing and/or
fire, and it may decline in the absence (or excess) of tliese. Leafy spurge is in early stages of invading
some of the most extensive areas of tliis habitat type in the state.

Dichanthelium oUgosanthes var. scribnerianum, Scribner's Panic Grass (G5T5, SI)
County Distribution: This plant has been documented at four sites in Powder River County, all on the
Ashland Distiict of Custer National Forest. It grows in openpondeiosa pine woodlands of valleys and
plains. There are few pine stands onBLM lands in the county, and of tliefew tliatwere surveyed, none
appeared to have suitable microhabitat.

Ecology and management considerations: This species occupies open pine woodland that may be af-
fected by vegetation encroachment and by grazing, particularly early in the growing season. It cannot
complete witli sod-fomiing grasses like Kentucky bluegrass (Poapratensis).

Status note: Since this species is restiicted to woodlands and has not been found on BLM lands in Mon-
tana, it could be dropped from BLM ''Watch" status.

Mentzelia niidOy BractlessMentzelia (G5, SI)

County Distribution: We documented tliis species from three locations in the northeastern comer of
Powder River County; these weie die first county records for it. Prior to this, it had not been reported
anywhere in Montana since 1957.

Ecology artd management considerations: In Powder River County, it was found in blowouts associated
with outcrops, and on tlie sandstone outcrops tliemselves. It could be vulnerable to road constniction,
subdivision, and exotic species invasion, however we identified no immediate management concerns.

Phlox andicolOy Plains Phlox (G4, S2)

County Distribution: We discovered this species at one location in the southeastern comer of Powder

River County; this was the first record of it for tlie county.

Ecology and management considerations: The single Powder River County population was found in a
parti ally -re vegetated blowout witli prairie sandreed {Calamoxilfa longifolia). sandhills bluestem
(Andropogon hallii), lemon scurfpea (Psoralea tanceolatd) and yucca {Yucca glauca). It is an early- to
mid-succession species of plains and woodlands, and is subject to encroachment by bettei- competing
species in more productive settings. Moderate levels of grazing and disturbances that reduce competition
may benefit the species. Anecdotal observations indicate it is favored by fall fire and winter grazing.

14

Physaria brassicoideSt Double Bladdeipod (G5, S2)

Coii/tty Distribution: It occurs in soutliwestem and possibly northeastern areas of Powder River County

where tliere are sandstone outcrops.

Ecology and management consideratioiis: Double bladderpod is restricted to sandy or stony soi! of open
grassland slopes on the plains. In Powder River County, it occupies secondaiy range. It grows where the
vegetation is sparse, often on steep slopes where tlie slope is unstable and there is little or no profile de-
velopment, and is vulnerable to competition from invasive exotics. Seeding of sweetclover {Melilotits
spp.) should be avoided near its habitat. It could also be vulnerable to road widening, maintenance, and
hei'bicide tjeatment.

Psoralea hypogaea, Little Indian Breadioot (G5T4, S2S3)

Comity Distribution: We found this plant on sandstone outcrops in tliree of tlie four comers of Powder

River County, and there are more records of it here tlian in any otlier Montana county. It was previously

reported from single isolated populations in smaller-scale studies (Heidel 1994, Heidel 1997, Vander-

horst et al. 1998). The sandstone outcrops of Powder River County are widespread but mostly small and

isolated, so tliese neu' location records suggest that tlie species is likely more widespread than previously

known.

Ecology and management considerations: This plant occupies ridgetop blowouts, and loose sand slopes
around isolated sandstone outcrops and tliose along the Powder River valley. Initial observations indi-
cate that it is not sensitive to grazing. The size of populations appears to be directly related to the extent
of available habitat, and it appears able to peisist in low, isolated pockets.

Status note : As a result of tliis inventory work, Little Indian Breadroot has been dropped as a state spe-
cies of concein, and we recommend that BLM drop it from ''Watch" designation.

Vegetation Communities

Based on our field surveys and previous studies, we have now documented a total of 46 native vegeta-
tion communities in Powder River County. These are listed in Table 4. Appendix E provides detailed
descriptions for 32 of tliese vegetation types. Where infomiation is available, these include composition
and distinguishing attributes, environmental setting, state and county distributions, global and state
status, and ecological or management considerations (NatureServe 2002). State status ranks for commu-
nities should be considered preliminary and will continue to be reviewed and revised as we acquire new
infonnation.

Several vegetation types were particularly noteworthy on BLM lands in the county, either by their extent
and good condition and/or as distinctive types tliat are uncommon or range-limited. In addition to col-
lecting data from vegetation plots to better document and understand these communities, we have also
identified areas where they are particularly well -rep re sen ted in high quality condition, witliin ecologi-
cally intact landscapes.

The discussion below highlights a few of the significant communities and representative areas tliatwe
documented during our surveys. Each area mentioned by name is summarized witli a site profile in Ap-
pendix B, which includes photographs and a map showing its generalized location and extent.

15

Table 4. Plant Associations found in Powdei' River County

Global

State

Scifiitiflc Name

Rank

Rank

WOODLAND

Fraxmns pennsydvanica / Pntnits virgimana Forest

GJ?

S2S3

Junipeiiis scopidorum / Piptathentm inicranthwn (= Oiyzopsis inicrarttha) Woo<lland

G3G4

S3

fiimpems scopidomm / Pseudoroegneria spicata Woodland

G4

S4

Pmtis ponderosa / Carex mops ssp. hdiophila Woodland

G3G4

S3S4

Pmtis ponderosa / Feshica idahoensis Woodlaud

G4

S4

Pmus pondsrosa / Jimipenis honzorttahs Woodlaud

<^?

S3

Pmics ponderosa / Pseudoroegneha spicata Woodland

G4

S4

Pirtus ponderosa / Pnmiis virginiana Forest

G3

S4

Popidus deltoides I Symphoricaipos occiderttalis Woodlaud

G2G3

S2S3

SHRUBLAND

Aitemisia tndentatCv ssp \vyom\ngens\s/ Pascopynim ssuithu Sluaib Herbaceous Vegetation

G4

S?

Aitemisia tridentata ssp. wyomingensis / Pseudoroegnena spicatii SlllTlbland

G5?

S5?

Artemisia tridentata ssp. wyomingensis -Alriplex confertifolia Shrubland

caos

S3

Artemisia cana / Pascopymm smithii Shniblaud

G4

S4

Artemisia cana ssp. cana / Pas copy nan ssnithu Shiiib Herbaceous Vegetation

G4

S?

Atriplex gardneri / Pascopynim smithii Dwarf-Shniblaud

C3

S3

Krascheninnihovia lanata / Hesperostipa (= Stipa) comata Dwarf-Shmbland

G3

S3

Rhus trilobata / Pseudoroegnena spicata Sluiib Herbaceous Vegetation

G4

S4

Salix exig\ia Temporarily Hooded Shiiibland

G5

S5

Sarcobattfs venmcidatiis / Artemisia tridentata Sluiiblaud

G4

S4

Sarcobatus venmcidatiis / Pseisdoroegneria spicata Sbnibland

C3

S3

Sarcobatus venmcidatiis / Pascopy-nun smithii Sluiib Herbaceous Vegelatiou

G4

S4

Symphoricaipos occidentaiis Temporaiily Hood Sluaibland

G4G5

S4S5

HERBACEOUS VEGETATION

Andropogon hallii - Calamovdfa longifolia Herbaceous Vegetation

G4G5

S7

Andropogon hallii - Carex inops ssp. heliophda Herbaceous Vegetation

GJ

S3

Calamovilfa longifolia - Carex inops ssp. heliophda Herbaceous Vegetation

Gi

S3?

Calamovilfa longifolia - Hesperostipa (= Stipa) comata Herbaceous Vegetation

<S

S3

Carex nebrascensis Herbaceous Vegetation

G4

S4

Carex pellita (_= laniigmosa) - Calamagrostis stricta Herbaceous Vegetation

GJG5

S3?

Eleocharis paliistris Herbaceous Vegetation

G5

S5

Festuca idahoensis - Carex inops ssp. heliophila Herbaceous Vegetation

<^

S3

Hesperostipa (= Stipa) comata - Carex filifolia Herbaceous Vegetation

G4

S4

Hesperostipa (= Stipa) comata - Carex inops ssp. heliophda Herbaceous Vegetation

G4

S4

Hesperostipa (= Stipa) comata - Bouteloua gracilis - Carex filifolia Herbaceous Vegetation

G5

S?

funciis balticHS Herbaceous Vegetation

G5

S5

Pascopyrum smithii Herbaceous Vegetation

G3G5Q

S4

Pascopyrum smithii - Bouieloua gracilis - Carex filifolia Herbaceous Vegetation

G4

S4

Pascopyrum smithi - Hordewn jubatiLm Herbaceous Vegetation

G4

S?

Phalaris antndinacea Western Herbaceous Vegetation

G5

S4

Pseudoroegnena spicata - Boutelona curtipendida Herbaceous Vegetation

<^

S3

Pseudoroegnena spicata - Carex filifolia Herbaceous Vegetation

G4

S4

Pseudoroegnena spicata - Pascopynim smithii Herbaceous Vegetation

G4

S4

Schizachyriwn scoparium - Boitteloita (curtipendida, gracilis) / Carex filifolia Herbaceous Vegetation

G3G4

S?

Schizachynum scoparium (_= Andropogon scoparius) - Carex inops ssp. heliophda Hcibaccoiis Vegetation G3

S3

Schoenoplectus (^Sciipiis) pungens Herbaceous Vegetation

G3G4

S3

Spartina pectinata Western Herbaceous Vegetation

GM

S3?

SPARSE VEGETATION

Eriogonum panciflonmi - Gtitierrezia sarothrae Badlands Sparse Vegetation

G4G5

S?

16

Grasslands

Pascopyriim smithii — Hesperostipa comata (western wheatgrass -needle-and-thread) and
Pascopyrmn smithii — Buchloe rf/ic/>7*;/rf^y(westfrnwheatgr ass — buffalo grass)

(See full description of Western wheatgrass Alliance communities in Appendix E, page 30)

Distribution: In Powder River County, western wheatgrass- dominated communities occur on gentle to
modeiate slopes ranging from 0-35 % and it is characteiistic of the widespread Silty Ecological Site of
the 10-14 inch precipitation zone. This type is prevalent on gentler slopes witliin the Elso-Midway-
Thurlow and the Elso-Remmit-Ocean Lake soil associations deiived from calcareous shales. It also
occurs on Silty Ecological Sites on well-drained deep-loam soils of the Elso - Ocean Lake association to
the north. It is occasional on upland and bench positions with suitable substiate in the Ringling-Cabba-
Midway association to tlie west, a Clayey Ecological Site of the 15-19 inch precipitation zone. InPow-
dei' River County, we documented tliis community with seveial different co-dominants including Hes-
perostipa comata and Biichhe dactyloides, tlie latter having not been previously documented and
apparently distinctive to tliis region. We recorded data from ten plots in this vegetation type and made
extensive field notes, with particular emphasis on documenting the communities co-dominated by
western wheatgrass and buffalo grass, which were extensive on BLM lands.

Representative sites: One area that is dominated by western wheatgrass — needle-and-tliread community
in particularly good condition was Five Mile Hill. We documented particularly good representation of
tlie distinctive western wheatgrass — buffalo grass community in two areas: Little Powder Hills and
Biddle Hills.

Ecology and management considerations: Altliough western wheatgrass communities are common
tliroughout a broad geographic range, heavy grazing and lack of fire may cause many stands to have a
high proportion of exotics. In the past, fire likely occuned commonly in tliis type. Fire, botli aboriginal-
and lightening-caused, was a regular part of this landscape. Fire-return intei'vals have been considerably
lengthened since settlement by European-Americans. Vast (singly and in the aggregate) black-tailed
prairie dog {Cynomys hidoriciarms) "towns" once developed on tlie favorable substrates in tliis
community and exploited its vegetation. Prairie dog populations have undergone significant decline
since settlement, so much of tliis type could be in various states of secondaiy succession, returning from
a somewhat denuded state and altered composition created by tlie prairie dogs as well as bison (Bos
bison) tliat found nutritious forage here.

Calamovilfa longffblia - Hesperostipa comata (prairie sandreed - needle-and-thread)

(See full description of this community in Appendix E, page 26)

Distribution: This is a rare upland community that was not previously documented in Montana. It oc-
curs in small patches on the landscape. In Powder River County, tliis plant association is found in the
Sandy Ecological Sites of tlie 10-14 inch precipitation zone.

Representative sites: We documented tliis community on the eastern edge of the county along Cabin
Creek. This site supports a diversity of otlier grassland types. The prairie sandreed - needle-and-tliread
community occurs on the upper portions of well-drained sandy slopes along watercourses and ridges.

Ecology and management considerations: This community can be highly susceptible to invasion by
exotic brome grasses and other non-native invasives.

17

Antlropogon hallii - CaliUHOvilfa loitgifoUa (sand blue^tem - prnii ie snndrecd)

(See full description of this community in Appendix E, page 22)

Distribution: This community types is characteiistic of sandy deposits, usually on gentle to moderate
slopes, ranging from stabilized rolling to choppy sand dunes. In Montana, where we do not have
extensive choppy dune systems, it is uncommon and widely -scatteied, associated with active wind
ei'osion. This association occurs at tlie ''rim" of blowouts at Medicine Lakes, but is so small and narrow
a vegetation band that it was not included in our description of plant associations in Sheridan County.
The unglaciated sedimentaiy plains of the Fort Union Fonnation in southeastern Montana provides more
habitat for it on active wind erosion featuies associated with sandstone outcrops, which are widely-
scattered in small pockets, hi Powder River County, this community is uncommon in areas with
sandstone outcrops in at least tlie eastern end of tlie county. It occurs witliin the 10-14 in precipitation
zone, and at higher precipitation levels elsewhere. This plant association or closely related ones
provides habitat for a number of Montana species of concern, including Chenopodium subglabrum,
Cryptcuithafeiuileri, Cyperits schweinitzii, Meutzeha nuda, and possibly otliers.

Ecology and Management Considerations: Blowouts may occui' in this community type, leading to bare
soils or subsoils. Blowouts may be related to seveie droughts and windstonns, and may occur in con-
junction with grazing pressures or fires tliat reduce the ability of the vegetation cover to stabilize tlie
sand.

Andropogon hallU - Carex mops ssp. heliophila (sand bluestem - sun sedge)

(See full description of this community in Appendix E, page 24)

Distribution: This sand bluestem prairie community type is found in restricted areas of the nortliern
Great Plains of tlie United States, including southeastern Montana and soutlieastemNoilli Dakota.,
where stands are typically less than a hectare in size. It occurs on gentle to steep sloping tenain with
sand or sandy loam soil, and in Montana, can occur on slopes of any aspect, witli nortli the least
frequent.

Ecology and Management Considerations: Blowouts may occur in this community type, leading to bare
soils or subsoils. Blowouts may be caused by severe droughts and windstorms, and may occur in
conjunction witli grazing pressures that reduce the ability of the vegetation covei' to stabilize the sand.
This community may be an early successional stage on tliese blowouts, where vegetation cover and
diversity are low.

Pseudoroegneria spicata - Bouteloua curtipendiila (bluebunch whe^tgrass - sideoats grnma)

(See full description of this community in Appendix E, page 36)

Distribution: This mixedgrass association occurs as small to large patches on foothills and sideslopes
along major drainages between the Tongue and Powder rivers of southeastern Montana. To date, it has
been documented only in soutlieastem Montana, although potential habitat exists in northeast Wyoming
and westernmost Noitli Dakota. It is considered a topo-edaphic climax by Hansen and Hoffman (1988)
because it occurs on moderate to steep slopes (>45%) witli large amounts of inegularly shaped, iron
oxide porcelainite shale (scoria), produced by fires in contiguous coal beds (liowever the soils are
conventional loams). These harsh sites produce a unique depauperate community with one of the lowest
total and giaminoid covers of any southeastern Montana community.

Ecology a/ td Management considerations: Given the low covei' and patchiness of this type, fires
probably burned in a mosaic fashion witli reduced intensity. It could be vulneiable to grazing, but stands

IS

are generally somewhat removed from watei\ These areas are generally not conducive to alien
bromegrasses, but tlieir susceptibility to invasion by other weeds is unknown. Pronghom antelope
(Antilocapra americana) use areas sites for grazing and predator detection.

Shrublands and Shrubland-Grasslands :

Artemisia truletUata ssp. wyomiiigensis — Pascopyrum srnitltii (Wyoming bigsagf - westfin wheat-
grass)

(See full description of this community in Appendix E, page 13)

Distribution: In Powder River County, this widespread Montana community occurs wheiever tlie
topography is dissected, and is especially extensive in the extreme soutliwestern comer of the county.
Over most of the county's shale plains, it is concentiated on tlie steeper slopes (greater tli an 8%) giving
way to giassland on gentlei' slopes. It occurs on Thin Silty Ecological Sites, with 10-14 in. precipitation
zone. It is not limited to steep slopes in all settings, and prevails at the extreme southwestern border of
the county on Silty ecological sites, where elevation is higher.

Representative sites: We found good stands of Wyoming bigsage - western wheatgrass at Chico Buttes
and in the Little Powder Hills. Botli are in good condition and exist in a landscape tliat is largely ecol-
ogically intact. The Little Powder Hills represents tlie cool phase of tliis community, with a co-
dominance of Carexfiiifoha (three-leaved sedge) in the understoiy. At Chico Buttes, tlie understory is
co-dominated by Nassefia xiridnla (green needlegrass), indicating a more mesic phase of this vegetation
type. The Chico Buttes site also supports a particularly rich stand witli species that were scarce or
absent elsewhere, including Calochortus mittcdliU (Nuttall's maiiposa lily), Besseya Myomingensis,
(Wyoming coral-drops), Limim lewisii (prairie flax), and gieen needlegrass.

Ecology and managemeni considerations: Taylor and Hoist (1976) refer to an ^'upland praririe sagebrush
ecosystem" of the Ashland Distiict and note that this sagebnish ecosystem overlaps strongly witli upland
grassland, appearing as an edaphic difference in places, and as a grazing disclimax in otliers. In Powder
River County, we found many areas of tliis community in good condition, indicating its edaphic origin.
Wyoming bigsage is killed within prairie dog towns. In Powder River County, vegetation sampling was
conducted on a bench along Buffalo Creek in what appeared to be a long-abandoned prairie dog town,
even tliough theie were no signs of buirow mounds remaining. Elsewhere on the bench, Wyoming
bigsage dominated in identical settings. In the abandoned prairie dog town, tliere was 50% covei' of
Wyoming bigsage and 10% cover of both ^^^^^^^^^/^^^(^(Sandbergbluegrass) mid Br omt is japonic us
(Japanese bronie), with high litter accumulation (greater than 60%). Perhaps tlie fertilizing and churning
influence of tlie praiiie dogs heightened productivity and impeded re-establishment of Wyoming bigsage
in the high vegetation and/or higli litter cover. Under heavy grazing pressure, the cover of exotic and
increaser species like Japanese brome, Hedeoma hispida (rough pennyroyal), Flaniago patagonica
(woolly plantain), and Vulpia octoflora (slender 8-flowered fescue) increases greatly.

Artemisia truletUata ssp. wyomiitgensis - Buchloe dactyloides (Wyoming bigsage - buffalo gi ass)

(This is referenced in Appendix E, page 15 under Wyoming bigsage-westem wheatgrass shrubland)

Distribution: We documented this vegetation type for the first time in Powder River County during
these surveys, where it occuned on BLM lands in much of the county. This community type has not
been well-documented elsewhere in tlie northem Gieat Plains.

Representative sites: We identified two particularly high quality landscapes with good stands of this
community type. In the Riddle Hills, Wyoming bigsage -buffalo glass occurred ovei' about half a

19

township in essentially undisturbed natural condition, witliin a functionally intact landscape. Buffalo
grass is also co-dominant (with western wheatgrass) in tlie giasslands of the Biddle Hills. One of tlie
few areas in the county where we found the Wyoming bigsage - buffalo glass community on clay
substrate (Ai^ada-Bone complex, rather than the typical silt substrate) was at the Cabin Creek site. It
occurs theie in good condition within an ecologically intact landscape.

Ecology Of td management considerations: We have no infomiation that is specific to this type.

Waodlands :

Pinus ponderoifa- Pseudoregneria \pic{ita (ponder 0%^ pine -bluebunch wheatgrass)

(See full description of tliis community in Appendix E, page 10)

Distribution: In Powder River County, this association is found on Shallow to Sandy and Silty
Ecological Sites in both 10-14 and 15-19 inch precipitation zones. It occurs on slopes witli coarse soils,
often with a high gravel or rock content, and occurs mostly on steep soutlierly aspects.

Representative sites: We identified ponderosa pine — bluebunch wheatgrass stands at Five Mile Hill that
are good condition second growtli. This site is one of seveial areas near Broadus tliat best represent the
''park-like" nature of tlie ponderosa pine community type. The Buffalo Breaks along the southwestern
edge of the county, east of the Powder River, has a complex system of steep ridge slopes covered by a
ponderosa pine woodland with some Juniperus scopiilorum (Rocky Mountain juniper ) in tlie
understoiy. The area is impressive in its extent and complexity, and supports a diverse complex of
woodland, steppe and grasslands similar to nearby National Forest lands.

Ecology and management considerations: Fire likely occurred at regular intervals in this type;
documentation on fire frequency is not available. The lack of Rocky Mountain juniper in many stands
may be attiibutable to past fires killing diis species and leaving tlie pondeiosa pine overstory intact, this
scenario has been documented by Culwell et al. (1991) in tlie Bull Mountains of central Montana.

Juniperus scopulorum - Piptatlterum micnuttJtum Woodland (Rocky Mountain juniper - little-seed
mountain riccgi ass)

(See full description of this community in Appendix E, page 6)

Distribution: In Montana, this association is best-developed on sheltered aspects in dissected
sedimentary plains. Witliin Powdei' River County, it is widely -scatteied on thin silty ecological
conditions, along noitli eastern escai'pments and dissected terrain along tlie soutli end of the Powder
River in the soutliwestern comer of the County. This type closely intergrades witli Ju/uperus
scopulortmi / Pseudoroegneria spicaia andbotli may be represented on the same slope or on opposite
aspects of the same landfomi, as we found tliem in the dissected terrain along die Powder River.

Ecology and Management Considerations: This plant association is in relatively moist habitat that is not
as prone to burning as sunounding vegetation types, but is highly flammable when diy. Rocky Moun-
tain junipei' is readily killed by fire; once ignited the crowns are almost always completely incinerated.

It often has grassland or steppe openings that influence the levels of overall livestock use. Signs of
fencepost cuttings are ubiquitous in tlie stands and the changes brought on by tliis histoiy need to be fur-
ther addressed in characteiizins stand structure.

20

Recommendations for future work

While tliis study added a great deal to knowledge of tlie vegetation and ecology of Powder River
County, it is far from comprehensive. One limitation was our focus on BLM lands - and principally
large blocks witliin tliose lands. While tliese lands support a diversity of community types, many in
good to excellent condition, tliey also tend to concentrate in certain types of landscapes, resulting in
oversampling of some features and undersampling of otliers.

For example, the more mesic river valleys and major draws stand out as one of tlie least-documented
vegetation complexes in tlie county, and one tliat we did not addiess, since they occur almost entirely on
private lands. Riparian communities have undergone major changes, including conversion to pasture
grasses and widespread loss of cottonwood regeneiation. Howevei, tliey continue to be extiemely im-
portant to a divei'sity of wildlife species. An understanding of biological resources in drainages and as-
sociated lowlands will be particularly important due to tlieir favorability as locations for coalbed meth-
ane wells and associated facilities. These areas are also of ti' emend ous importance for a diversity of
wildlife species. This study did not address fauna at all, and future efforts should include wildlife, em-
phasizing species of concern and lesser-known groups such as small mammals, reptiles and amphibians,
and songbirds. It may also be valuable to better understand the effects of existing riparian modifications
on wildlife species populations and diversity, to help in evaluating the impacts of potential futuie modi-
fications and identify management options.

Forb diversity was relatively low in many of tlie communities that we documented. This would be wor-
thy of fui'ther documentation to detemiine its extent and to identify patterns related to geology, geogra-
phy and/or land use history (e.g., sheep grazing).

Much of Powder River County has not yet been extensively invaded by many invasive exotic weeds that
pose serious thieats elsewhere in the state. Continued documentation of tliose weeds that are present
and/or invading will be important to safeguarding tlie rangeland values provided by native vegetation
communities. We did note a significant presence of Japanese and smootli bronie. The ecological impact
of these species on tlie native communities and species has not been evaluated, to our knowledge, and
may be woithy of further attention.

Our survey efforts were also limited by time and tlie scale of the project, which was relatively modest.
We designed our approach to provide a representative overview of vegetation types on BLM lands, how-
ever many tracts were not visited, and among tliose tliat we did survey, none were systematically inven-
toried and many were far too large to be more than sampled. In addition, portions of the counfy are
quite remote witli limited access, which imposed restrictions on the reach of our ground surveys.

It would also be worthwhile to extend survey work to significant state land holdings in the southeastern
part of the county, and into Custer National Forest in the west. All of these additional efforts would con-
tribute to developing a tnily integrated portrait of the biological resources and dynamics in this large,
diverse and relatively intact landscape.

21

LITERATURE CITED

Booth, W. E. 1950. Flora of Montana, part 1, conifers and monocots. The Research Foundation at
Montana State College, Bozeman, MT. 232 pp.

Booth, WE. and J. C. Wright. 1966. Flora of Montana, Part II. Dicotyledons. Montana State Univei-
sity, Bozeman, MT. 305 pp.

Connelly, J.W., M.A. Schroedei, A.R. Sands and C.E. Braun, 2000. Guidelines to manage sage grouse
populations and their habitats. Wildhfe Society Bulletin 28 (4): 967-985.

Culwell, L. D. 1979. Vegetation communities of tlie Coal Creek study area, Powdei' River County. Re-
port to Coal Creek Mining Company. Western Technology and Engineering, Inc. Helena, MT.

Braun, C. E., O.O. Oedekoven, and C. L. Aldridge, 2002. Oil and Gas Development in Western North
America: Effects on Sagebrush Steppe Avifauna witli Particular Emphasis on Sage-grouse.
Transactions of the North American Wildlife and Natural Resources Conferences. 67: In Press.

Dorn, R. D. 1984. Vascular Plants of Montana. Mountain West Publishing, Cheyenne, WY. 276 pp.

Dorn, R. D. 1992. Vascular Plants of Wyoming. Mountain West Publishing, Cheyenne, WY. 340 pp.

Fabei'-Langendoen, D. 1999. Tenestrial Vegetation of the midwestern United States. Compiled com-
munity characterization abstiact in draft fonn. Midwest Office of The Nature Conservancy,
Minneapolis, Minn.

Fertig, W., C. Refsdal, and J. Whipple. 1994. Wyoming Rare Plant Field Guide. Wyoming Rare Plant
Technical Committee, Cheyenne, WY.

Great Plains Flora Association. 1977. Atlas of the flora of the Great Plains. Iowa University Press,
Ames, lA. 600 pp.

Great Plains Flora Association. 1986. Flora of the Gieat Plains. University Press of Kansas, Lawrence,
Kansas. 1392 pp.

Grossman, D.H., D. Faber-Langendoen, A.S. Weakley, M. Anderson, P. Bourgeron, R. Crawford, K.

Goodin, S. Landaal, K. Metzler, K. Patterson, M. Pyne,M. Reid, and L. Sneddon. 1998. Inter-
national Classification of Ecological Communities: Terrestrial Vegetation of tlie United States.
Volume I. The national vegetation classification system: development, status, and applications.
The Nature Conservancy, Arlington, Virginia. USA. 126 pp.

Hansen, P. L. and G. R. Hoffman. 1988. The vegetation of the Grand River/Cedar River, Sioux and
Ashland Distiicts of the Custer National Forest: a habitat type classification. Gen. Tech. Rep.
RM-157. USDA Forest Sei^ice, Rocky Mountain Forest and Range Expeiiment Station. Fort
Collins, CO. 68 pp.

Heidel, B. L. 1994. Survey for PSORALEA HYPOGAEA in the Great Falls Resource Area, Lewistown
District. Unpublished report to tlie Bureau of Land Management, Montana. Montana Natural
Heritage Program. 22 pp. plus appendices.

22

Heidel, B. L. and K. H. Dueholm. 1995. Sensitive plant species survey in the Sioux District of Custer
National Forest, Carter County, Montana and Harding County, Soutli Dakota. Unpublished re-
port to the Custer National Forest. Montana Natural Heritage Program, Helena, MT. 95 pp.
plus appendices.

Heidel, B. andH. Marriott. 1996. Sensitive plant species survey in tlie Ashland District, Custer Na-
tional Forest. Report to the U.S. Forest Service. Montana Natural Heritage Program, Helena.

Heidel, B.L. 1997. Preliminaiy Botanical Survey in the Tongue River Area, Montana. Unpublished
report. Montana Natural Heritage Program, Helena. 11 pp. plus appendices and map.

Hitchcock, C. L. and A. Cronquist. 1973. Flora of the Pacific Nortliwest. University of Washington
Press, Seattle. 730 pp.

Husby, P., J. Antos, J. Elliott and T. Olson. 1979. Vegetation inventoiy and analysis of the Montco pro-
ject area. Report to MONTCO. Olson-Eillott and Associates. Helena, MT.

Kartesz, J.T. 1999. A Synonymized Checklist and Atlas witli Biological Attributes for the Vascular
Flora of the United States, Canada, and Greenland. Fiist Edition. In: Kartesz, J.T. and C.A.
Meacham. Synthesis of the North Ameiica Flora, Version 1.0, North Carolina Botanical Gar-
den, Chapel Hill, NV. August.

Montague, C.,L. C. Munn, G. A.Nielsen, J. W. Rogers andH. E. Hunter. 1982. Bulletin 744. Boze-
man, MT. Montana Agricultural Experiment Station, Montana State University. 95 pp.

Montana Native Plant Society. 1993. Guidelines for collecting plants. Reprint from Kelseya Newslet-
ter. Bozeman, MT. 2 pp.

Natural Resource Conservation Service. 1980. Draft: Report of Field Review of Mapping Units in Soil
Survey of Powder River County area, Montana. June 6, 1980.

Natuial Resource Conservation Service. 2001. Plants Database. http.//p lants.usda.gov. plants/. Data
accessed in May, 2001.

NatuieSei've. 2002. Intemational Classification of Ecological Communities: Teirestrial Vegetation.
Natural Heritage Central Databases. NatureSeive, Arlington, VA.

Parker, J. L., L. R. Guptill, K. M. Bajema, W. A. Berg, L. Logan, and R. E. Adams. 1971. Soil Survey
of Powder River Area, Montana. Soil Conservation Service (Natural Resources Conservation
Service), Bozeman, MT.

Ross, R. L. and H. E. Hunter. 1976. Climax vegetation of Montana based on soils and climate. Boze-
man, MT. U.S. Department of Agriculture, Soil Conservation Service. 64 pp.

Taylor, J. E. and T. L. Hoist. 1976. Grass and shnib plant community classification. USPS Contiact
Research Project 26-3494. Final Report, Ashland Distiict, US Forest Service.

The Nature Conservancy. 1999. Ecoregional Conservation in the Northern Great Plains Steppe. 181
pp.

23

Vanderhorst, J., Cooper, S. V. and B. Heidel. 1998. Botanical and vegetation survey of Carter County,
Montana. Unpublished report to Bureau of Land Management. Montana Natural Heritage Pro-
gram, Helena, MT. 116 pp. + app.

24

Appendix A: Global / State Rank Definitions

HERITAGE PROGRAM RANKS

The international network of Natural Heritage Programs employs a standardized ranking system to de-
note global (range-wide) and state status (Association for Biodiversity Information 2001). Species are
assigned numeric ranks ranging from 1 (critically imperiled) to 5 (demonstrably secure), reflecting the
relative degree to which tliey are ''at-risk". Rank definitions are given below. A number of factors are
considered in assigning ranks — tlie number, size and distribution of known ''occuixences" or popula-
tions, population tiends (if known), habitat sensitivity, and tlireat. Factors in a species' life history tliat
make it especially vulnerable are also considered (e.g., dependence on a specific pollinator).

RANK DEFINITIONS

Gl SI Critically imperiled because of extreme rarity and/or othei' factors making it highly

vulnerable to extinction.

G2 S2 Impei'iled because of rarity and/or other factors making it vulnerable to

extinction.

G3 S3 Vulnerable because of rarity or restricted range and/or othei' factors, even tliough it may

be abundant at some of its locations.

G4 S4 Apparently secure, though it may be quite rare in parts of its range, especially at tlie

pei'iphery.

G5 S5 Deinonstiably secure, tliougli it may be quite rare in parts of its range, especially at the

pei'iphery.

GU SU Possibly impeiiled, but status uncertain; more infomiation needed.

GA SA Native in nearby states, but in Montana believed to be accidentally introduced,

deliberately planted, or escaped from plantings.

GH SH Historical, known only fiom records over 50 year ago; may be rediscovered.

GX SX Believed to be extinct: historical records only.

COMBINATION RANKS

G#G# or S#S# Indicates a range of unceitainty about the rarity of the species.

SUBRANKS

T# Rank of a subspecies or variety; appended to the species' global rank of the full species,

e.g. G4T3.

QUALIFIERS

Q Taxonomic questions or problems exist, more information needed; appended to the

global rank, e.g. G3Q.

? Denotes uncertainty or for numeric ranks, inexactness.

Appendix A-1

Appendix B: Site Descriptions

Site Map for Powder River County

j:> -> I III i^ruFJ bjy-UEDr>

wf^-'—lff^ hpIf^ui.

14 UAWfis CD ^r^s Doundarief

USFS
Tribal

B^ St3t? Tiu^t
Other privBts
Water

Appendix B-1

FIVE MILE HILL

Photo by Bonnie Heidel

Location

Approximately 3 miles W of Broadus. MT and 2 miles N; public road access on E side of Higliway 59.

General Description

The site is a portion of sandstone outcrop escai'pment between tlie Powder River and Mitzpah River,
with pine-covered outcrop knolls and intei'vening gently rolling grasslands.

Vegetation Communities

The grassland community is co-dominated by Pascopyntm smithii (western wheatgrass) at 10+ % cover
and Hesperostipa comata (needle-and-thiead) at 30% cover. Short-stature giaminoids are not readily
apparent but the cover oiCarex i/tops (sun sedge) cover exceeds 10%. The most important forbs in
temis of cover are Androsace occidentalis (western rockjasmine) and Sphaeralcea coccinea (red globe-
mallow). Boutelona gracilis (blue gramma) increases and western wheatgiass decreases in higher to-
pogiaphic positions. Plot data was taken in mesic habitat at Ihe lower end of tlie gradient, perhaps simi-
lar in site characteristics to adjoining fannland.

The open woodland community is dominated by Pimts ponderosa (ponderosa pine) at approximately 5%
and Pseiidoroegiieria spicata (bhiebunch wheatgrass) at +/- 20%, sometimes joined by sun sedge and
Schizachyrium scoparium (little bluestem) at 0-3%. The associated forbs are present in tiace amounts,
including Campanula rotimdifoha (American harebell), Heterotheca rillosa (hairy golden-aster), and
Br/ckelha eupatorioides (thoroughwort brickerbush).

Environmental Characteristics

The series of small hills is typical of escarpments on the plains, covered by pine woodland, interspersed
with giassland and sparse vegetation. Soils range from gravelly silt loams to loamy sands, and fall
within the Ringling slaty loam, 20-50% slope unit. The gentle noilliem toe-slope setting is part of a
well-drained perimeter diat flanks the sandstone and scoria outcrops of Five Mile Hill, on Hapley and
Relan loams, witli a 4-8% slope. The pine-covered hills and open perimeter lie widiin productive up-

Appendix B-2

lands that are eithei' conveited to familand or tamegrass, or more intensively utilized.

Significance

The giassland community represents a ''large patch" type in good condition, within a landscape that is
ecologically intact in part. The botanical and ecological diveisity is good but limited by size, and in
places by condition. The ponderosa pine community is a 'Marge patch" type represented here by second-
growth stands in good condition. It is among tlie areas near Broadus that best represents a "park-like"
pine community, and could serve as a stewardship demonstration site.

Land Management

Public recreation access is provided via a gate and scoria road on the east side of the highway. A trailer
for BLM fire-fighting crews is parked in the middle. The area is popular for local recreational use, in-
cluding parties and target practice.

Exotics

Annual bromes are common on exposed outcrop slopes and Poapratensis (Kentucky bluegrass) is com-
mon in swales between knolls.

Appendix B-3

FIVE MILE HILL

CHICO BUTTES

Photo by Bonnie Heidel

Location

Approximately 17 miles S and 2 miles W of Foit Howes Work Station, in a valley NW of tlie road.

General Description

This is a productive Artemisia thdentata ssp. •wyotmngensis—Fciscopyrum stttithii (Wyoming big sage-
bmsh-wes'tem wheatgiass) shrub -herbaceous community tliat occupies some of the county's best-
condition rangelands; the coinninnity spans dissected terrain and an unmodified watercourse. The area
includes the transition from sagebrush community to tlie surrounding grasslands. Artemisia iridentata
ssp. Myo/nhtgeiisis (Wyoming bigsage) cover becomes prevalent to tlie soutli and west; our sui'vey was
incomplete and limited by access, and tliis community likely includes additional BLM lands to the soutli
that could not be accessed.

Vegetation Communities

The area is dominated by Wyoming big sagebmsh widi covei' at or below 20%. The understory is co-
dominated by westem wheatgrass and Nassetla riridula (green needlegiass) both approaching 20%
cover, and witli Koeleria macrmitha (prairie junegrass) and Bro/mis japonic us (Japanese brome) also
having between 10-20% cover. The most common forbs mt Achillea millefoliiim (common yaiTo),
Phlox hoodii (Hood's phlox), Gutierrezia saroihrae (broom snakeweed) ^n^A]yssum desertorum (desert
alyssum), approaching 1% cover. Codominance by green needlegrass indicates tlie most niesic phase of
this association in Powdei' River County.

Environmental Characteristics

This is in die only major area of the Kyle-Midway-Cabba soil association in Powder River County,
which has a relatively higli clay component It occupies tlie head of a nortli -trending valley that cuts into
a prominent, open ridge where the valley has among tlie best soil development in tliis landscape on tlie
Midway and Elso Rocky Soils, with 35-75% slope. Grassland vegetation prevails over the ridgetop and
sparsely vegetated communities dominate on certain aspects and lilhologies of the side-slopes.

Appendix B-4

Significance

The Wyoming bigsage-westem wheatgrass community typically occurs as large patches on the land-
scape; it is present here in good condition in an ecological setting that is largely intact.

Exotics

Japanese biome is present with 10-20% cover in the Wyoming bigsage community.

Appendix B-5

CHICO BUTTES

LITTLE POWDER HILLS

.-.£^

?^^^.v^^-- ^.-'^-

Photo by Boiuiie Heidel

Location

North of Horse Creek, approximately 7 miles N of Biddle, MT, 4.5 miles E on Belle Creek Rd and 1.5
miles N, following a seiies of turns going primarily N for about 2.5 miles to tlie only public access for
the site from tJie soutli.

General Description

The Little Powder Hills are a series of ridges and valleys along side tiibutaries of tlie Little Powder
River. Horse Creek has tlie broadest valley of tliose tributaries, with prairie dog towns and some tame-
grass hayland. Abrupt, scattered ridgecrests and valley rims have siltstone outcrops, and support the
most extensive upland successional communities. Giasslands predominate, grading into sagebmsh
steppe on steep, upper slopes and in tlie intact valleybottoms.

Vegetation Communities

A productive Artemisia trideniata ssp. wyomingejisis (Wyoming bigsage) steppe community, witli sage-
bmsh cover exceeding 30%, dominates tlie higlier slopes and topographic positions. The understoiy is
co-dominated by Pascopyrum smithii (western wheatgrass) at over 30%, Koeteria mewrantha (prairie
junegrass) at less than 30 %, and Carex fiUfoUa (tliread-leaved sedge) at less tlian 20%. Co-dominance
by tliread-leaved sedge represents tlie cool phase of tliis association in Powder River County.

Environmental Characteristics

Side tributaries of tlie Little Powder River dissect the uplands. Grasslands prevail, with scattered ridge
outcrops and steppe on their uppei' north-facing slopes. The shrub communities grade into grassland
with decreasing slope and lower topogiaphic position, and into sparsely vegetated communities on ex-
posed aspects. Soils are Midway - Elso, with 8-35?'o slope. The Elso and Midway soil series predomi-
nate, originating from a siltstone of remarkable unifonnity. Widely scattered areas of sandstone out-
crops occur at lower elevations.

Appendix B-6

Significance

The Wyoming bigsage steppe is a community that occurs as large patches on the landscape, and is repre-
sented here in good condition within a landscape that is largely ecologically intact. This site includes
good habitat for Astragalus Barrii (Barr's milkvetch). It also has good to excellent examples of the
Pascopyrum smithii - Buchloe dactyloides (western wheatgiass - buffalo glass) plant association, and
occupied Cynoinys ludoricianus (black-tailed prairie dog) habitat that is probably 500-1000 acres. It is
also high quality \\?ih{\.?ii for Antilocapra ainericafui (prongliom).

Land Management

The area is rangeland tliat spans at least two allotments. A couple inclusions of tamegrass plantings ex-
ist as well (unknown whether they are still hayed).

Exotics

Exotic species are limited to annual bromes ?ind Makolittia qfricafta (African adder's -mouth).

Appendix B-7

LITTLE POWDER HILLS

BUFFALO BREAKS

Photo by Boimie Heidel

Location

E of Moorehead. MT extending from the Wyoming state line N along the Powder River to Buffalo
Creek and the range of hills paralleling it on tlie NE.

General Description and Vegetation Communities

The area is a complex system of steep ridge slopes covered by Pimis pouderosa (ponderosa pine) with
some Jtmiperus scopnforum (Rocky Mountain juniper) siiirounding long, flat isolated ridgetops. It also
encompasses a segment of the broad Buffalo Creek valley.

Key Environmental Factors

Soils are part of tlie Ringling-Cabba-Midway association, witli shallow slaty loams and clay loams.

Significance

This area has a diveisity of woodland, steppe and grassland habitats which are similar to nearby National
Forest lands on the same soils series, noteable in tlie extent and complexity more than their condition. It
also has high habitat value for big game. Buffalo Creek includes extant and fonner prairie dog towns,
with interesting successional patterns.

Land Management

The entire area is rangeland. Portions of this area have a histoiy of heavy livestock use, including tracts
along tlie Powder River. Most of the complex lies within a BLM roadless study area.

Appendix B-8

BUFFALO BREAKS

BIDDLE HILLS

Photo by Boimie Heidel

Location

The site lies 1 ainiiile soutlieast of Biddle, MT. The main access is via tlie Rancli Creek Road, going

app. 8 miles east, and 3.5 miles south, tlien west 2 miles west on oil well roads, above Prairie Dog

Creek.

General Description

The Biddle Hills are a series of dissected ridges and eroded site tiibutaiies of the Little Powder River.
Siltstone outcrops are consistently exposed at different levels, with some of tlie most extensive outcrops
being on die knolls and spines that top the ridges. Grassland predominates, and giades into sagebrush
steppe in steep upper slopes.

Vegetation Communities

The steppe community is dominated by (Artemisia tridentata ssp. y\yomingeusis) Wyoming bigsage with
cover approaching 30%. The understoiy is codominated by Pascopynim smithii (western wheatgrass) at
30 % and Buchloe dactyloides (buffalo grass) at 50%. The only forb with more tlian trace cover is Achil-
lea milkfohum (common yano). This community is recurrent over an area that covers about half a
township.

The herbaceous grassland community is dominated by western wheatgrass (over 30%) and buffalo gi'ass
(over 60%). The most common forb is Agoseris glauca (pale false-dandelion), at slightly more tlian
trace cover. This community is prevalent over an area tliat is about half a township.

Environmental Characteristics

The uplands are sharply dissected uplands by tjibutaries of tlie Little Powder River, widi scattered ridge
outcrops, and steppe on tlieir upper, more sheltered slopes. The shmb communities grade into grassland
with decreasing slope and lower topographic position, and into sparsely vegetated communities on ex-
posed aspects. Soils are part of the Elso-Midway-Thurlo soil association with 8-35% slope, and are
some of tlie most unifonn siltbeds in tlie area.

Appendix B-9

Significance

This area supports the largest and most ecologically intact populations of Bair's milkvetch on BLM
lands in Montana. Tlie Wyoming big sage - western wlieatgrass community ranges fiom good to
excellent condition and the landscape is largely functionally intact from an ecological perspective. It
was also the first site in the County where we documented buffalo grass as a co-dominant under essen-
tially undisturbed conditions.

Land Management

The area is made up of several range allotments. It is bordered by oil wells on the east. A wide, new
road tiaverses much of the site.

Appendix B-10

BIDDLE HILLS

Cabin Creek

Photo by Boimie Heidel

Location

Near tlie eastern edge of the county, along Cabin Creek, about 13 miles N of Boyes, MT, primarily NW
of Moore Road.

General Description

Tliis area is characterized by gently rolling upland plains and widely scattered drainages. Dominant vegetation is a
diversity of grasslaud types, all with Hespevostipa comata (needle- and-thread). Large areas of Wyoming big sage-
bmsh grassland are interjected oumidslopes. The upper segments of well-diained sandy slopes along watercourses
and ridges are co-dominated by Calamomlfa longifolia (prairie sandreed).

Vegetation Communities

This area supports two significant vegetation types. The grassland is a Calaiuoxilfa longifolia -
Hesperostipa comata (prairie sandreed - needle-and-diread) commimity, botli species witli about 20%
cover. CarexfiUfolia (tliread-leaved sedge) and C inops (sun sedge) are each present witli about 10%
cover, and tliere is a diversity of forbs (27 species recorded), witli only Ambrosia psilostacfn/a (naked-
spike ambrosia) abundant.

The shmb -herbaceous community on Ihemidslopes is doimn?itQd by Arte tries ia tridetitata ssp.
}]yomii}gefisis (Wyoming bigsage), witli cover over 10%. The understoiy is co-dominated by
Pascopyrum smithii (western wheatgrass) at 30% cover and Buchloe dactyloides (buffalo grass) at 40%
cover.

Environmental Characteristics

A range of sedimentaiy bedrock materials not apparent from the topography underlies tlie uplands and
drainages. Soils are Remmit-Ocean Lake, with 8-25% slopes and Arvada-Bone complex widi 0-4%
slopes.

Appendix B-11

Significance

The prairie sandreed - needle-and-thread association is a rare upland community that typically occurs in
small patches on tlie landscape. The Wyoming big sagebrush - western wheatgrass - buffalo glass) com-
munity is a large-patch community occurring here in good condition in a landscape setting tliat is ecol-
ogically intact. This is one of die few areas in the county where this shiiib -herbaceous community was
found on clay substiate (Arvada-Bone complex), normally occurring on silt.

Appendix B-12

CABIN CREEK

>>

a

'^'S

\

^

Appendix B-13

Appendix C, Powder River County - Plant Species of Concern

Table of Contents

Barr's Milkvetch 1

Pregnant Sedge 4

New Jersey tea 5

Smootli Goosefoot 6

Schweinitz' Flatsedge 7

Scribner's Panic Grass 8

Bractless Mentzelia 10

Plains Phlox 10

Double Bladdeipod 11

Little Indian Breadroot 12

Literature Cited 14

Illustration and Photo Credits:

Jeanne R. Janish Figure 20, 28 (From 'Vascular Plants of the Pacific Nortliwest')

Debbie McNiel Figure 1,24, and 26

John Challey Figure 21

JoeDuft Figure 18

Bonnie Heidel Figuie 3-7, 9, 15, 16, 19, 22, 23, 25, 27, 29 and 30

Hollis Mairiott Figure 11 and 12

Steve Shelly Figure 8

Dee Strickler Figure 2

The New York Botanical Garden Figuie 10, 13, 14, and 17

Reprinted With permission Ji'om the New Britton and Brown Illustrated Flora of the

Northeastern United States and Adjacent Canada, Vol. 1, page 310, Copyright 1952, The New York

Botanical Garden

Astragalus barrii Barneby

Ban's mi Ik vetch

Bean Family (Fabaceae)

BLM status: Watch

USFS status: Sensitive

Global rank: G^, State rank: S3

State status summary: Ban's milkvetch is a

regional endemic with more tlian 20 occunences in

Montana. It has no immediate tlireats but is

potentially vuhierable to exotic species invasion

through disturbances of fire and coalbed metliane

developments.

Description: Ban's milkvetch is a perennial tliat
grows in low. dense mats. Leaves have 3 nairowly
lance-shaped leaflets 1 to 4 cm long and densely
covered witli short white hairs (Figures 1 and 2).
Stipules at the leaf bases are membranous. Puiple
or pinkish -purple pea shaped flowers are borne in a
naiTow, open, and few-flowered inflorescence

Astragalus gilxiflorus and Astragalus Jn/aUtius.
Both have white flowers and a longer calyx tube (6
to 16 mm) Wiinn Hit Astragalus barrii calyx tube
length (2.8 to 5 mm). They also have peduncles
that are short (<3.5 mm) or absent compared to
Astragalus barrii peduncle lengtli (7 to 24 mm).

Figure 1. Illustration oi Astragalus barrii

(Figure 3). The petals are 7 to 17 mm long. The
calyx is 3 to 5 mm long and densely covered with
long, white hairs. The sparsely white, haiiy pod is
nanowly elliptical, 4-8 mm long, and 1 to 2 mm in
diameter. Flowering occurs in May-early June and
fmiting from late May-June.

The only other mat-fomiing species with 3-leaflets
in the range of Astragalus barrii in Montana are

Figure 2. Photograph oiAsirag^iIus barrii

Distribution: Ban's milkvetch is a regional
endemic found at die jiuictions of northwestern
South Dakota, nortlieastem Wyoming, and
soutlieastern Montana. In Montana it has been
collected from four counties, but one of tliese
represents a single historic record that has not been
relocated. Besides tlie historic Carter County
record, tliere are a total of 3 5 other records for the
species. Half of tliese (18) are in two areas of
concentration and may represent two large
population complexes.

Both of tlie large concentrations of Astragalus
barrii are in Powder River County, which has a
total of 23 known records for tlie species. As
mentioned above, 18 of tliese in die County are
highly concentrated and may represent two large
population complexes along part of Otter Creek
and tlie Little Powder River. In visits to tlie latter,
we detemiined that the species repeats consistently
in the landscape where suitable habitat is extensive
so that some of tliese records are very large. We
also began documenting intei'vening records diat
connect tlie concentiations of 18 records.

Astragalus barrii has die higliest number of records
among tlie Montana species of concern in tlie study
area, and is tlie only one tliathas a geographically
hi a few cases, the gentler teirain of the Midway-

Appendix C-1

Figure 3. Photograph of Astragalus barrii
(close-up)

Hmited distribution beyond state borders. We
represent its distribution in the county by a separate
symbol in tlie map showing locations of plant
species of special concern in Powder River County
County (see tlie map labeled Figure 1 1 in tlie body
of the report).

Note: In tlie course of this study, we detennined
\h^i Astragalus hyalimis is much more widely
distributed than previously known in tlie western
and southern parts of the County. It cannot be
distinguished vegetatively from Astragalus barrii,
but has a white or cream-colored flower tliat
readily distinguishes it during flowering (Figure 4).
All new records of Astragalus barrii were veiified
using flowering mateiial. They also differ in tlieir
habitat, with Astragalus hyalinus restricted to
settings witli sandstone outcrop. We note that
Astragalus barrii superficially looks like tlie
Qou\n\of\ Astragalus spathulatus, but the latter has

an elongated flowering stalk (Figure 5). A
complete set of technical distinguishing
characteristics hQ\}N^^w Astragalus barrii and
Astragalus ftyalinus is summarized in Heidel and
MaiTiott(1996).

Habitats: Barr's Milkvetch is restricted to sparsely
vegetated knolls, buttes, and barren hilltops, on
calcareous soft shale and siltstone. It is often found
at tlie rim of outcrops and midslope benches
(Figure 6). These microhabitat settings represent
thin silty ecological sites. Their clay fraction is
high enough in places to classify tlie microhabitats
as thin clayey. There is little or no soil profile
development but there are generally no restrictive
layers that would classify the microhabitats as a
shallow ecological site. These microhabitats occur
within predominantly silty ecological sites, but
while tliey occupy a small fraction of the
landscape, they are widespread and recurrent in
part of BLM-administered lands (Figures 7 and 8).

Figure 4. Photograph of Astragalus Irvaliuus
(note white flowers)

Figure 5. Photograph of Astragalus spathulatus
(note stalked flowers)

This species is restricted to uppei-and mid-slope
topographic positions and does not occupy outwash
or eroded gullies below die outcrops. It is most
commonly found on slopes widi noitliem and
eastern aspects and does not occur on steep soutli-
facing slopes with their salt-affected vegetation. In
otlier words, its habitat represents a small subset of
outcrop settings and a small subset of tlie thin silty
ecological site.

In Powder River County, Bair's Milkvetch is
found, almost witliout exception, on die Midway-
Elso rocky soils on 35% to 70% slope (Parker et al.
1971).

Appendix C-2

Elso rocky soils
(8% to 35%) is
the mapping
unit. Soil
textures range
from silty clay to
loam, and are
frequently
unifomi silt
loam. The soil
surface is often
unifonii silt but
may have a
veneer or be
embedded with
pebbles and
cobbles.

Figure 6. Habitat of Astragalus
barrii

The Little
Powder River

habitat is on tlie open plains while the Otter Creek
habitat is in a pineland setting, but they otliei'wise
have similar species composition. The sparse
vegetation has many of the same species present
from place to place even if the relative cover of
any one of tlieni is variable. The most common
shiiib is usually Wyoming big sagebrush
(Artemisia tridentata uyomittge/isis). The most
common grass that we noted on BLM lands is
western wheatgrass (Pascopynmt swithii) or else
tliickspike wheatgiass (Elyitius lauceolains) on
level terrain, but neitlier is mentioned among the
associated species on Custer National Forest
(Schassberger 1988, 1990). Otiier directly-
associated species typically include leafy musineon

Figurt 7. Landscape of Astragalus barrii
habitat

{Mnsifieon diraricatum), broom snakeweed
(Gutierrezia saroihrae), few-flowered buckwheat
(Eriogounm paucijlorum), textile onion (Allium
textile), cushion goldenweed (Haplopappus
acauUs, x goldenweed (Haplopappus armerioides),
and {Hyinenoxys richardsomi). There are species
tliat have been characterized as pait of associated
vegetation in past reports and as part of the
information recorded for individual records,
however, they are actually found on adjoining
sandstone substrates ratlier tlian soft shale with
Astragalus barrii. Plants such as little bluestem
(Andropogon scoparius) and soapweed (Yucca
glauca) do not generally occupy tlie same
microhabitats as Astragalus barrii while tliey may
be common and conspicuous all around it.

Comments: The species almost always occurs in
habitats considered secondaiy range, in addition,
the plant is not grazed due to its low gi'owth foim.
It is little- affected by allotment management
practices and developments unless concentrated
livestock trampling occurs in its habitat.
Astragalus barrii
is potentially
vulnerable to
exotic species
encroachment It
is an early-
succession species
and its forested
habitat settings
may be subject to
increased tree
canopy cover.
Any revegetation
efforts should
avoid seeding
sweetc lover
(Melilotus spp.) in
proximity. There
is little

encroachment by
weedy annuals at

present. The fine texture and instability of the soils
limit invasion by annual bromes. A non-native
mustard, malcolmia (Malacolmia africana), is in
early stages of invading fme-textured slopes of
Powder River County and elsewhere. It appears to
be spreading along backroads.

Figure 8. Habitat of Astraga-
lus barrii above Horse Creek

Appendix C-3

Carex gravida Tuckerm. van gravida

Pregnant sedge

Rush Family {Cyperaceae)

BLM status: Watch

USFS status: Sensitive

Global rank: G5T5?, State rank: SI

State status summary: Pregnant sedge is known

from fewer than six occun'ences. Its habitat is in

primary range that is potentially affected by

glazing and logging.

Descriptions: Pregnant sedge is » perennial grass-
like plant tliat fomis clumps of stems that reach up
to 6 dm higli and arise fiom short root stocks.
Leaves are 4 to 8 mm wide and clustered near tlie
base of tlie plaut. Flowers are clustered in egg-
shaped spikes tliat are about 1 cm long; tbe female
flowei's (perigynia) occupy most of the spike, but
there are a few male flowers at tlie tip (Figures 9
and 10). Spikes are aggregated at tlie top of tlie
stem and subtended by 2 to 3 leaf-like bracts that
are shorter tlian tlie inflorescence. Scales
subtending each perigynia are oval with a long
point at the tip. The perigynia are 4 to 5 mm long
and egg-shaped; tliey gi'adually taper into a beak
that is seirate on tlie edges and notched at the tip.
There are few or no nei'ves visible on the outer face
of the perigynia. There are 2 stigmas, and tlie seed
is 2-sided. Fruit matures in late Jiuie-July.

Carex is a large
and difficult
genus; there are
many species
similar to Carex
grm'ida. The awn-
tipped scales of
the perigynia,
relatively broad
leaf blades
(gieater than 3.5
mm) and loose
sheath help
distinguish it from
the closely -related
Carex hoodii with
which it overlaps
in distribution. A
hand lens or

Figure 10. Photogiaph of
Carex grmida var. gravida
(close-up)

Figure 9. Illustration of Carex
gra\idav3.v. grmida

microscope and
teclmical key are
essential for
positive
detenu in at ion.

Distribution :

Pregnant sedge is

an eastern species

tliat is peripheiai

in Montana,

extending from

Saskatchewan to

Pennsylvania,

south to New

Mexico. Texas.

Missouri and

Vii'ginia. In

Montana, it is

known from only

tliree southeastern

counties, including Big Horn, Powder River and

Rosebud counties. It has only been found in two

places on the Ashland District of the Custer

National Forest (Heidel and Mamott 1996), and

these represent the known Powder River and

Rosebud records. In the course of this survey tliere

was veiy little suitable habitat in the areas that were

visited, so it was not found and no additional data

was collected on this species and its distribution.

Habitat: This species is restricted to open woods
on the plains, often in ravines with deciduous tiees
in a setting that is witli or witliout flowing watei\
The ravines border oveiflow ecological sites. In the
Ashland Distiict, the species occurs along ravine
bottoms dominated by a combination of gieen ash
and chokecherry {Fraximis peimsyhoiiica / Pritnus
y/rginia/ta) within pine woodland (Figure 1 1). In
some cases, aspen (Populus treitniloides) is present.
Other associated species include seivicebeny
(.'iitte lane hie r ahnfoUa). Hood's sedge (Carex
hoodii). Toney's sedge {Carex torreyi) and
SprengePs sedge (Carex sprengelii), and otlier
plants of eastern deciduous woodland.

Comments: This species seems restiicted to mesic
microhabitats witliin pine woodland, making it
particularly vuUierable to changes in pine
woodland stmcture and composition as affected by

Appendix C-4

grazing and logging. These settings are vulnerable
to invasion of exotic species like Kentucky
bluegrass (Foa prate Jis/s).

There were fire scars among the Ponderosa pine
(P'nuis ponderosa) at one of tlie Ashland Disti'ict
sites where the species was found suggesting tlie
plant can survive ground fire.

Figure 11. Habitat of C^r^.i; grcnidav^.
^ai7V/i7 (Custer Natl. Forest).

Ceanothus herbaceus Raf,

New Jersey tea

Bucktliorn Family {Rhammtceae)

BLM status: Watch

USFS status: -

Global rank: G5T?. State rank: SH

State status summary: New Jersey tea is known

from one historic occuirence in Montana. It may

be declining elsewhere on tlie Great Plains.

Relocation efforts have not been successful to date.

Description: New Jersey tea is a higlily branched
shmb witli stems up to 1 m high. The alternate,
lance-shaped to nan'owly elliptic leaves are 2 to 6
cm long and have seirated edges; they are glabrous
on top but hairy beneath. Nimierous white flowers
are bom in congested, rounded inflorescences that
temiinate tlie growing branches (Figures 12 and
13.) Each flower is about 2 to 3 mm high with 5
calyx lobes and 5 petals tliat have a linear basal
portion and a hood-shaped blade. There are 5
stamens and a 3-lobed ovary. The fiuit is a glossy,
brown, 3-lobed, globose capsule that is 3 to 5 mm
wide. It flowers in June,

The Ceanothits genus has simple alternate leaves

with 3 prominent,
somewhat parallel
veins arising from
nearly the same
point near the base
of the blade. It
also has hood-
shaped petals, and
3-lobed fniits.
Ceanothus
herbaceous can be
distinguished from
otlier members of
the genus by its
naiTower leaves,
which are less tlian
2 cm wide and not
shiny on the upper
surface.

Figure 12. Illustration of
Ceatiothtis herbaceus

Distribution: New Jersey tea is an eastern species
tliat is peripheral in Montana. It grows from
Quebec to Manitoba to eastern Montana, and south
to Georgia, Texas, and Colorado. In Montana, tlie
plant is knov^ai from a historic record in Powder
River County-
There are few pine stands represented on BLM
lands in die study area. Of tlie few tliat were visited

in tlie course of
this survey, none
appeared to have
suitable

microhabitat. It is
not known
whetlier tliis
species is
restricted to
pineland habitat in
Montana, and tliis
species was also
sought in the
closest grassland
habitat on BLM
lands. No
additional data
were collected on
tliis species and its
distribution.

Figui^e 13. Photogiaph of
Ceanothus herbaceus

Appendix C-5

HRbit»t: The single collection label for tliis species
in Montana described the setting as a ''grassy, pine-
covered hill." It may represent a sandy, stony, or
gravel ecological site, hi tlie Gieat Plains, this
species occupies rocky prairie hillsides, roadsides
and open pine forests.

Comments: Management considerations are
unknown. This species has diminished elsewhere
on the Great Plains (Ode, pers. comin.) Some
species of Cecutothiis are higlily palatable to
wildlife and livestock.

Chenopodium subglabrum (S. Wats.)
A. Nels,

Smootli goosefoot

Goosefoot Family (Chefiopodiaceae)

BLM status: Watch

USFS status: -

Global rank: G3G4, State rank: SI

State status summary: Smootli goosefoot is

known from fewer tlian six occurrences in

Montana, one of which may be extirpated. It

occupies early-succession habitat tliat is potentially

affected by grazing, changes to river flow regimes.

and noxious weeds.

Df scriptions: Smooth goosefoot is an annual with
erect, simple, or high stems (2 to 3) 8 cm (Figure

14). The alternate
leaves are linear
witli entii"e
margins, single
veined, glabrous,
up to 3 cm long.
The small, green
flowers are
grouped in remote
clusters in simple
or branched spikes
(Figure 15). Each
flower lacks petals
but has 5 glabrous
sepals and 5
stamens. The one
seeded fiiiit is
compressed
hemi spherically
and is relatively

Figure 15. Photogi'aph of
Cheiiopodinm subglabrum

Figure 14. Illustration of
Chenopodium subglabrum

large; 1 to 2 mm
across, exposing
a jet-black fmit
at maturity diat
readily separates
from tlie pericarp
(fruit wall).
Fruiting occurs
in late June-July.

Cheiiopod'wm
subglabrum
sometimes
occurs with and
is related to
Chenopodium
leptophyUum.
They both have
linear, single-
veined leaves but
tlie latter are

farinose white (mealy usually wiiitish colored).
Chenopodium leptophylhmt also has densely-
clustered flowers, a relatively unbranched growtli
fomi, fmits usually 1 mm or smaller, and seeds
which do not detach from the pericarp.

Distribution: This species is known from the Great
Plains, extending from Manitoba to Alberta, and
south to Kansas and Nevada. It is also in the
Midwest, including Michigan and Missouri. Plants
of the Pacific Northwest, including Washington,
Idaho and Oregon, are said to differ from Great
Plains material (Crawford 1973) and tlieir proper
disposition has not been resolved. It is centered in
tlie Nebraska Sandhills and widely scattered in five
eastern Montana counties.

The species was documented in Powder River
County and on BLM-administeied lands for die
first time during tliis study, where it was found in
the northeastern comer of the County.

HRbit»t: CJienopodium subglabrum occupies two
main kinds of settings, namely sparsely vegetated
sand dunes and sandy tenaces of major rivers on
the plains. Only one of the five Montana records,
located in Custer County, was from a riparian
setting on the Tongue River. All five records
represent sandy ecological sites. This species is a

Appendix C-6

poor competitor and is associated with otiier
annuals and early-succession species.

The Powder River County setting is an isolated
ridgetop blowout rather tlian a sand dune (Figure
16). This is a different setting tlian has been found
to date, and may mean that tlie species is not so
nanow in its habitat requirements as previously
interpreted. It was resti'icted to one segment of tlie
blowout rim where sand was being deposited, in
association witli lemon sciuTpea (Psoralea
lofweolata), sandhills bluestem (Aitdropogoit hallii)
and western spideiwort (Trade scatttia
occidenlaJis). While diere were no other nearby
ridgetops widi blowout features, tlie Midway -
Rock land association and the sandy ecological site
that it represents are widespread (Parker et al.
1971). They are associated with many other
landfomis capped by sandstone.

The were no records of CJienopodium subglabrum
documented in the few riparian settings we
surveyed where we had access along tlie Powder
River.

Comments: Maintenance of early serai habitat in
the upland settings requires a balance of fire and/or
grazing. Maintenance of early serai habitat in the
riparian setting requires intact flow regimes and
landscape processes over a larger scale. Tamarisk
control is needed in riparian habitat, and leafy
spurge is at early stages of invading some of tlie
most extensive upland habitat.

Figurf 16. Habitat of Che Jtopodium
subglabrum (Medicine Rocks SP)

The Powder River population occurs in sccondaiy
range, where livestock use is light and water
sources are remote.

Cyperus schweinitzii Torn

Schweinitz' flatsedge
Rush Family {Cyperaceae)

BLM status: Watch

USFS status: -

Global rank: G5, State rank: S2

State status summmy: Scliweinitz' flatsedge is

known from 6 to 20 occurrences, most of which

have low numbers. It is an early-succession

species, affected by absence or excess of

disturbance and potentially tlireatened by noxious

weeds.

Description:
Schweinitz'

flatsedge is a

giass-like

perennial widi

stems diat are 10

to 40 cm higli,

arising from short,

irregularly

swollen rhizomes

(Figure 17). The

leaves are 1 to 4

mm wide and

located mostly

near die base of

the plant. The

inflorescence is

subtended by 3 to

6 long, leaf-like

bracts, some of

which are wider Uian tlie leaves (Figure 18). The

inflorescence is made up of ascending clusters of

flattened spikelets tliat are 5 to 25 mm long and

borne on stalks that are very short to long. The

flowers are crowded opposite each other and

consist only of a small, pointed scale, which is

about 3 to 4 mm long and subtends 3 stamens and

an ovaiy. The seed is triangular in cross-section.

Fmit mature in late June-July.

This is our only perennial Cyperus and is the only
one occurring in upland habitat.

Figure 17. Illustiation of
Cyperus schwewitzii

Appendix C-7

Distribution: This species occurs from Albeita to
Quebec and soutli to New Mexico and West
Viiginia. It is concenti'ated around tlie Great Lakes
and tlie Great Plains. It is known from five
counties in eastern Montana.

This species was
documented for
tlie first time in
Powder River
County at two
sites in tlie
nortli eastern
comer.

Habitat: In the
Great Plains, it is

resti'icted to
sparsely vegetated
loose sand, most
often associated
witli sand dunes.
A typical sand
dune blowout is

Figure 18. Photograph of ^^^^^^ '" ^^^^""^

Cvpenis schweimtzii (close-up) ^^- ^^ occupies

sandy ecological

sites.

The Powder River County settings represent small
blowouts at toeslope positions where there is loose
sand eroded from sandstone outcrops above. This
is a different setting than has been found to date,
and may mean that tlie species is not so naiTow in
its habitat requirements as previously intei'preted.
It was more common in the setting where tliere was
more wind erosions. Associated species included
prairie sandreed (Calamovilfa lougifoha).
tlireadleaved sedge {Carex fihfoUa), and western
spidei'wort {Trade sc antia occidentalis). While this
species often overlaps with Chenopoditim
snbglabnuti (discussed previously), and is found in
a wider range of successional conditions, it was not
found in tlie same habitats in tliis study.

While there were no other nearby blowout features
along Cedar and Stump creeks, the Elso-Ocean
Lake association and the sandy ecological range
site tliat tliis landscape represents are widespread
(Parker etal. 1971).

Comments: Maintenance of tlie species' early-
succession habitat requires balances involving
grazing and/or fire. The species may decline in tlie
absence or excess of these. Leafy spurge is in early
stages of invading some of its most extensive
habitat in the state.

The Powder River populations occur in primaiy
range, and tliey are sufficiently far from Cedar and
Stump creeks tliat the range is in good-excellent
condition. There are no associated management
concerns.

Figure 19. Habitat of Cypents scfnvei/titzii
(Sheridan Co.)

Dichantheliiim oligosanthes (J, A.
Schultes) Gould van scribnerianum

(Nash) Gould

Scribner's panic glass
Grass Family (Poaceae)

BLM status: Watch. This species is not known

from BLM-administered lands in Montana and is

recommended for dropping accordingly.

USFS status:

Global rank: G5T5, State rank: SI

State status summary: Scribner's panic grass is

known from fewer tlian six occurrences. Most

have low population numbers and one represents a

historic record. It is potentially affected by grazing

and logging.

Dtscription: Scribner's panic grass is a perennial
tliat fomis clumps of simple or branched stems 1 to
6 dm tall (Figure 20). The lower leaves are 3 to 10
cm long and 3 to 12 mm wide, while the upper

Appendix C-S

Figurt 20. II Initiation of
Die hanthe dlium o Ugosanthes
var. scribiiericumm

leaves are short
and relatively

broad. Leaves are
mostly glabrous,
but tlie sheatlis
sunonnding tlie
stem are glabrous
to long-haiiy.
There is a short
fringe of hairs on
tlie leaf where it
meets tlie stem,
which is known as
a ligule. The
flowers are bonie
on short-to long-
stalks, which are
airanged in a
conical

inflorescence tliat
is 5 to 8 cm high
(Figure 21).
Inflorescences of tlie main stems are larger than
tliose of die branches. Each egg-shaped spikelet
has one flower, is abont 3 mm long, and consists of
two glumes enclosing a lemma and a palea tliat
may or may not be haiiy. Fmit matures in late
June - early July.

The relatively
large, egg-shaped,
single-flowered
spike lets help
identiiy this as
Dichwithelun/t.
This species
branches mainly in
the upper portions
of the stein, while
Diclmiitheluim
yvUcoxiaimm
usually branches
near tlie base. A
hand lens or
microscope and
technical key are
needed for positive
detenu in at ion.

Figure 21. Photograph of
Dichanthehum oligosantfies
var. scribneriamim

eastern United States, extending from southern
Canada to Mexico. It is peripheral in Montana,
where it is known from both die Flathead Valley
and from four records in Powder River County.
The latter are all on the Ashland Distiict of Custer
National Forest.

Habitat: In Montana, this species is only known
from open ponderosa pine woodlands of valleys
and plains (Figure 22). These woodlands fall

Distribution: This species is widespread in tlie

Figure 22, Habitat oi Dichanthehum
oligoscatthes var. scribnerianum

within \Ug Fi/ttis po/t^erosa / Mahonia repem
habitat type, comprised of silty ecological sites
with fine sandy loams and loams. The associated
species include bluebunch wheatgrass
{Pseudoroegneria spicata). Sprengel's sedge
(Carex sprengeUii), Dewey's sedge {Carex
de^veycuid). and field milkvetch (Astragalus
agrestis). DichaiHhedhniti oligosanthes has two
gi'owtli foniis in different times of the growing
season, requiring partial or direct sunlight
throughout tlie season.

In Powder River County, it has only been found in
four places on tlie Ashland Dishict of Custer
National Forest. There are few pine stands
represented on BLM lands in die study area. Of
tlie few tliat were visited in tlie course of this
siu'vey, none appeared to have suitable
microhabitat. No additional data were collected on
this species and its distribution.

Other: This species occupies open pine woodland
that may be affected by vegetation encroachment
and by grazing, particularly early in tlie growing

Appendix C-9

season. It does not compete with sod-foniiing
grasses like Kentucky bluegrass (Poa prate mis).

One of the Ashland District sites where the species
was recorded had burned (occuirence no. 003).
Only one plant was found, indicating a capacity for
sui"vival witliout providing basis for interpreting
species' response to fire. We note that
Dichajithelium mlcoxiaitiim, which has a similar
growth form, was locally common following tlie
1988 wildfires in the Sioux District (Heidel and
Dueholin 1995).

Mentzelia nuda (Pursh) Torrey &
Gray

Bractless mentzeha
Loasa Family (Loaseae)

BLM status: Watch

USFS status: -

Global rank: G5, State rank: SI

State status summary: Bractless mentzelia is

known from over five occunences in Montana, but

three of tliem are historic and the numbers of plants

in most occurrences are low.

Dtscription: Bractless mentzelia is an herbaceous
biennial or short-lived perennial witli one to a few
erect, branched stems that arise from a taproot and
are up to 1 m higli. The lance-shaped, alternate
leaves are 4 to 10 cm long, have deeply-tootlied
margins, and are petiolate below but sessile above.
Foliage is covered with short, barbed hairs tliat
cause it to stick to clotliing like Velcro. Flowers
that open in late afternoon are borne on short stalks
arising from the axils of reduced uppei' leaves, or
bracts. Each flower is 4 to 9 cm across and has 10,
non-overlapping, white petals and numerous
exseited stamens (Figure 23). The calyx fomis a
deep bowl widi 5 narrow, pointed lobes diat are 10
to 25 mm long; it also contains the ovary and bears
tlie stamens. The cylindrical seed capsules are 2 to
3 cm long. Flowering in July.

By comparison, Mentzelia decapetala has larger
flowers diat are 8 to 15 cm across, and its petals
overlap.

Distribution: This species occurs from eastern
Montana to Soudi Dakota, and south to Colorado

and Texas. Li
Montana, it has
been collected
from four
counties. It was
documented fiom
Uiree occunences
in the noitlieastem
comer of Powder
River County,
representing tlie
first county
records for it.
Prior to tliese. it
had not been
reported in the
state since 1957.

Figure 23. Photogiaph of
Menztelia wida

Habitat: The

species occupies
sandy or gravelly soil of open hills and roadsides
on the plains. These habitats represent sandy, tiiin
sandy, and shallow to gravel ecological sites.

In Powder River County, it was found in blowouts
associated with outcrops, and on the sandstone
out c r op s til em s el ve s .

Comments: This species is potentially affected by
road constiuction, subdivision, and exotic species
invasion. The principal habitat and perturbation
ecology of this species still needs clarification. All
of the population numbers in the study area weie
veiy low, but tliere were no immediate
management concerns identified.

Phlox andicola E. Nels.

Plains phlox

Phlox Family (Pofemoiuaceae)

BLM status: Watch

USFS status: -

Global rank: G4, State rank: S2

State status summary: Plains phlox is known

from over five occunences. The numbers of plants

at most occunences are low, but it may be more

widespread in Montana than records indicate.

Dtscription: Plains phlox is a pereimial herb with
loosely tufted stems Uiat are 4 to 10 cm high arising

Appendix C-10

from creeping rhizomes. The 5 to 8 pairs of
opposite, linear leaves have prominent midveiiis
and whitish bases and are 10 to 25 mm long, about
1 mm wide and come to a shaip point. Foliage is
glabrous to sparsely hairy. Stems are white. One
to five white flowers are borne at die stem tips
(Figures 24, 25) Each flower has 5 petals and a
tubular corolla. The calyx is also tubular, witli 5
lobes, tangled long hairs, and 6 to 11 mm lengtli.
Flowering in May-early June.

The leaves of Fhlox hoodii are usnally less dian 10
mm long, and tlie leaves of Phlox afyssifolia are 2
to 5 mm wide. Flowers are needed for
detemiination, and hybridization between tliese
species is reported elsewhere in the range.

Distribution: This species is disti'ibuted from

eastern Montana and North Dakota, south to
Colorado and Kansas. In Montana it is known
from Carter, Powder River and Sheridan counties.

Plains phlox was only located once in the
soutlieastem comer of Powder River County,
representing tlie first county record for it.

Figure 24. Illustration of Phlox andicota

Habitat: This species occupies sandy soil of
grasslands and open pine woodlands on die plains.
Most of tJie settings are well-vegetated, yet there is
still bare giound. Associated species are mid-
successional and usually occupy sandy ecological
sites.

The single Powder River County population was
found in a sandy ecological site, in partially-healed
blowout habitats, associated witli prairie sandreed

(Calamoxilfa longifoha). sandhills bluestem
(Andropogon halhi), lemon scurfpea (Psoralea
lojiceofata) and yucca {Yucca glattcd).

Comments: It is an early- to mid-succession
species of plains and woodlands subject to

Figure 25. Photograph of P/iJox aitdicola

vegetation encroachment in the more productive
settings. Anecdotal observations indicate that it is
favored by fall fire and winter glazing. Grazing
and disturbances tliat reduce competition may
benefit tlie species at low levels.

Physaria brassicoides Rydb,

Double bladdeipod

Mustard Family (Brassicaceae)

BLM status: -

USFS status: -

Global rank: G5, State rank: S2

State status summniy: Double bladdeipod is

known from over five occuiTences in Montana,

these witli mostly low numbers ofplants.

Description: Double bladdeipod is a perennial
herb with numerous ascending stems that are 2 to
17 cm long and arising from a basal rosette that
surmounts a branched crown and large taproot.
The basal leaves are 2 to 8 cm long and are spoon-
shaped witli long petioles (Figure 26). The few,
alternate stem leaves are broadly lance-shaped.
Foliage is covered with silveiy, star-shaped hairs
appressed to tlie suiface. The yellow, stalked
flowers are borne at tlie tops of tlie steins in a
narrow inflorescence that elongates as Hie fruit
matures (Figure 27). Each flower has 4 separate

Appendix C-11

Figure 26. Illustration of Physaria
brassicoides

petals that are 9 to 12 mm long and 4 separate
sepals. The ascending, inflated fmits are 1 to 2 cm
long, at least as wide, and flattened on top. They
are 2-lobed witli the locules (lobes) more deeply
defined above than below. There are 2 ovules in
each of the locules, attached at the top of the
replum (suture between tlie two locules), and tlie
replum has a linear outline. The style is 6 to 9 mm
long. Flowering in May-early June, fruiting in
June -July.

There are many similar-appearing P/fv^^/vf/.
Physaria didymocarpa is reported fiom
sontheastem Montana. It differs from Physaria
brassicoides having a replum that is obovate to
elliptic; ovules usually 4 per locule, and funicles
not restiicted to apex. A technical manual and
hand lens or microscope will be required for
positive identification.

Distribution: This species is a regional endemic of
southwestern North Dakota, soudieastem Montana,
eastern Wyoming and western Nebraska. In
Montana, it is known fiom three counties to date,
including Carter, Powdei' River and Peti'oleum
counties. It was first documented in the state in
1994 (Heidel and Dueholm 1995, Heidel 1996).

Habitat: Double bladderpod is restricted to sandy
or stony soil of open grassland slopes on the plains.

It grows where tlie vegetation is sparse, often on
steep slopes where tlie slope is unstable and there is
little or no profile development. Most settings
represent sandy or tliin sandy ecological sites.
Associated species may include bluebunch
wheatgrass {Pseudoroegneria spicatum),
goldenweed {Heterotlieca rillosa). indian ricegrass
(Oiyzopsis hymenoides), skunkbush (Rhus
f^romatica), wild begonia {Runtex \ei\osns) and
yucca {Yucca
glattca).

Comments :

The species is
vulnerable to
exotic species
competition.
Avoid seeding
sweet clover
(Melihtfis spp.)
in the area. It is
also potentially
impacted by
road widening,
maintenance,
and herbicide
treatment. It

occupies
secondaiy range.

Figure 27. Photograph of
Physaria brassicoides

Psoralea hypogaea Nutt.

Little Indian breadroot
Bean Family {Fabcweae)

BLM status: Watch

USFS status: -

Global rank: G5T4, State rank: S2S3

State status summary: Little Indian breadroot is

now treated as a watch species, in light of survey

results documenting its breadtli of distribution and

indicating low vulnerability. Theie are fewer tlian

twenty occurrences in widespread, localized

habitats of eight eastern unglaciated counties.

While it is often found in low numbers, it persists

under disturbance and annual brome grass

encroachment.

Description: Little Indian breadroot is a perennial
herb tliat consists of a rosette of long-petioled
leaves diat are palmately divided into 3 to 7 linear-

Appeadix C-12

elliptic leaflets that are 25 to 50 mm long witli a
deep, club-shaped root that is up to 6 cm long and
suiiTiounted by a subteiraiiean connecting stem
(Figure 28). Above giound, the plant foliage is
covered witli dot-like glands and dense, white
appiessed hairs, but tlie upper leaf surfaces become
glabrous with age (Figure 29 and 30). Blue, pea-
like flowers are borne in condensed spikes arising
among tlie bases of the leaf petioles at or barely
above giound- level. The tubnlar calyx is 6 to 9
mm long and has 4 long, nairow lobes and a fifth
that is longer and broader. The upper petal is 10 to
13 inm long and held foi'ward. The haiiy pods are
egg-shaped, ca. 5 mm long, and each has a beak
tliat is 5 to 13 mm long. Flowering late May -June.

Figure 28. Illustration of Psoralea In^ogaea

The common breadroot, Psoralea escnieiita, has a
distinct flowering stem widi spreading pubesence
on the stem and leaf petiole, while Psoralea
hypogaea is stemless witli appressed pnbesence.
Its flowers are at ground-level.

Distribution: This species of the western Great
Plains is found from eastern Montana soudi to
Texas and New Mexico. In Montana, it is widely
distributed across unglaciated plains, documented
from eiglit counties to date.

Figure 29. Photogiaph of PsoraJe a hypogaea

tlian in any otlier county. It was otherwise reported
from single isolated populations in studies diat
were mainly smaller in scale (Heidel 1994, Heidel
1997, Vanderhorstetal. 1998). The sandstone
outcrops of Powder River County are widespread
but mostly small and isolated, so we make
inference from the new disti'ibution information
that die species is likely to be more widespread
tlian previously known.

Habitat: Little Indian breadroot occupies sandy
ecological sites: mainly in the 10" to 14"
precipitation, zone across grasslands and open pine
woodlands on die eastern sedimentaiy plains. It is
often found in tlie loose sand below sandstone
outcrops, but is known from reworked alluvial sand
deposits. It tends to occur in sparsely -vegetated
niicrohabitats where more tlianhalf of tlie bare
sand soil surface is exposed. Associated species
include sand-loving species such as prairie
sandreed (Calamorilfa longifoUa), Indian ricegiass
{Oryzopsis hymenoides), annual buckwheat
{Eriogoimin atmuum), priaire lupine (Litpimts
lepidus), and western spiderwort {Tradescantia
occideniahs). The dominant species of the
suiTounding uplands may be inteniiingled,
including blue giama (Bouteloua gracilis), needle-
and-tliread (Stipa comata) and little bluestem
{Schizachyrium scopariwn). Botli common Indian
breadroot (Psoralea escutentd) and silver scurf-pea
{Psoralea argopJn'Ua) may occasionally be present
in low numbers or in the suiTounding grasslands.

It was found in three of Uie four comers of Powder
River County, and diere are more records of it here

Powder River settings included ridgetop blowouts,
and loose sand slopes around isolated upland

Appendix C-13

Figure 30. Photogiapli of Psoralea hypogaea
including root

sandstone outcrops and those of tlie Powder River
valley.

Comments: Initial obseivations indicate tliat it is
not sensitive to grazing and related indirect
influences. The size of populations appears to be
directly related to tiie extent of available habitat,
with a capacity to persist in low, isolated pockets.

Heidel, B. and H. Marriott. 1996. Sensitive plant
species survey in the Ashland Distjict,
Custer National Forest. Report to tlie U.S.
Forest Service. Montana Natural Heritage
Progi'am, Helena.

Heidel, B. L. 1997. Preliminaiy Botanical Survey
in the Tongue River Aiea, Montana.
Unpublished report. Montana Natural
Heritage Progiam, Helena. 11 pp. plus
appendices and map.

Parker, J. L., L. R. Guptill, K. M. Bajema, W. A.
Berg, L. Logan, and R. E. Adams. 1971.
Soil Sui'vey of Powder River Area,
Montana. Soil Conservation Service
(Natural Resources Conservation Service),
Bozeman, MT.

Schassberger. L. A. 1988. Status review of

Astragalus barrii. Custer National Forest.
Unpublished report, Montana Natural
Heritage Progiam, Helena. 61 pp.

LITERATURE CITED

Doni, R. D. 1984. Vascular Plants of Montana.
Mountain West Publishing, Cheyenne,
WY. 276 pp.

Heidel, B. L. 1994. Survey for PSORALEA

H\TOGAEA in tlie Great Falls Resource
Area, Lewistown District. Unpublished
report to tlie Bureau of Land Management,
Montana. Montana Natuial Heritage
Program. 22 pp. plus appendices.

Schassberger, L. A. 1990. Report on die

conservation status oi Astragalus barrii, a
candidate threatened species. Unpublished
report to the U.S. Fish and Wildlife
Service, Denver. Montana Natural Heritage
Program, Helena. 85 pp.

Vanderhorst, J., S. V. Cooper, and B. Heidel. 1998.
Botanical and vegetation survey of Carter
County, Montana. Unpublished report to
Bureau of Land Management. Montana
Natural Heritage Progiam, Helena. 116 pp.
+ app.

Heidel, B. L. and K. H. Dueholm. 1995. Sensitive
plant species sui'vey in tlie Sioux Distiict of
Custer National Forest, Carter County,
Montana and Harding County, Soutli
Dakota. Unpublished report to tlie Custer
National Forest. Montana Natural Heritage
Program, Helena. 95 pp. plus appendices.

Appendix C-14

Appendix D: Rangeland Ecological Sites and Plant Associations

Range Ecological Sites and Plant Associations
Sedimeutaiy Plains, East(MLRA 5SAE)

Ecological Site Types

Plant Associations Fonnd Within Diffei'eiit Precipitarton Zones

10 to 14 inch

15 to 19 inch

Riparian Subirrigated

• Salix extgua Temporarily Flooded

• Populus deltoides / Symphoncarpos

Riparian Meadow

• Spartina pectinata Western Herba-
ceous Vegetation

Riparian Emergent

• Schoenoplectus pungens ^txh^cto\\%
Vegetation

• Phalanx arundmacea Herbaceous
Vegetation

• Phalavis arundinacea Herbaceous
Vegetation'

Subirrigated

• Eleocharis paliistris Herbaceons
Vegetation

• Symphoncarpos occtdentalis Shrub-
laud^

• Pacopynim smtthii - Hovdeum juba-
tum Herbaceous Vegetation

• Eleochans palustns Herbaceous
Vegetation

• S[Taphoricarpos occidentalis Shrub-
land'

• Pacopynim sraitha - Hordeum juba-
tiim Herbaceous Vegetation

Saline Lowland

• Sarcobatus vermiculatus / Pascopyrum

smithii (Elymus lanceolatii:^) Shmb
Herbaceous Vegetation

Saline Upland

• Sarcobatus vsrmiculatus / Pseu-
doroegneria ^picata Slirubland

• Sarcobatus vermiculatus - Artemisia
tndentata Slirubland

• Sarcobatus vei'miculatiis / Pseu-
doroegnena spicata Shrubland

• Sarcobatus vermiculatus -Artemisia
tndentata Shnibland

Wet Meadow

• Cavex nebrascensis Herbaceous Vege-
tation

• Cavex lanuginosa - Calamagrostis
stncta Herbaceous Vegetation

• Jimcus balttcus Herbaceous Vegeta-
don'

• Carex nebrascensis Herbaceous
Vegetation

• Carex lanuginosa - Calamagrostis
stncta Herbaceous Vegetation

• Juncus balticus Herbaceous Vegeta-
tion'

Closed Depression

• Eleocharis palnstns Herbaceons
Vegetation

• Pacopyrum smithti - Hordeum juba-
tum Herbaceous Vegetation

• Pacopyrum smtthii Herbaceous Vege-
tation

• Eleochans palustns Herbaceous
Vegetation

• Pacopynim sraithn - Hovdeum juba-
tum Herbaceous Vegetation

• Pacopyrun\ smithii Herbaceous
Vegetation

Appendix D-1

Ecological Site Types

Plane Associatioiis Found Within DifTereiit Precipitation Zones

10 to 14 inch

15 to 19 inch

Overflow

• Artemi:^ia cana / Pascopymni smithu
Shnibland

• Artemisia cana ssp. cana / Pascopy-
rum smithu Shnib Herbaceous

• Symphoncaipos ocadentcdis Shnib-
land'

• Fraxvms pennsylvamca / Prunus vu-
gmiana Forest

• Pmiis pondevosa / Pnimis virgimana
Forest

• Artemisia cana / Pascopyrum smithu
Shrubland

• Artemisia cana ssp. cana / Pascopy-
rum smithu Shnib Herbaceous

• Symphoncavpos occtdentalis Shnib-
land'

• Pinus ponderosa /Carex maps ssp.

heliophila Woodland

• Pinus pondevosa / Festuca idahoen-

sis Woodland

• Pmus pondevosa / Pseudoroegneria

• Pinus ponderosa / Pseudoi'oegneria

spicata Woodland

spicata Woodland

• Andropogon halln - Calamovilfa

• Andropogon halhi - Calamovilfa

longifolia Herbaceous Vegetation

longifolia Herbaceous Vegetation

• Calamovilfa longifolia - Hesperostipa

comata Herbaceous Vegetation

• Festuca idahoensis - Carex mops ssp.
heliophila Herbaceous Vegetation

• SchiZQchyrium scopanum - Bouteloua

(cnrtipendula, gracihs) / Carex filifo-

lia Herbaceous Vegetation

Sandy

• Schizachyi'uim scopanum - Cai'ex

• Schizachyrium scopanum - Carex

mops ssp. hcliophila Herbaceous

inops s:^p. heliophila Herbaceous

Vegetation

Vegetation

• Hesperostipa comata - Bouteloua

• Hespei-ostipa comata - Bouteloua

gi'acilis - Carex fill folia Herbaceous

gi'acili:^ - Carex filifoha Herbaceous

Vegetation

Vegetation

• Hesperostipa comata - Carex mops
ssp. heliophila Herbaceous Vegeta-
tion

• Calamovilfa longifolia - Caies mops

• Calamovilfa longifolia - Cares mops

ssp. hsliophila Herbaceous Vegeta-

ssp. heliophila Herbaceous Vegeta-

tion'

tion'

• Krascheninmkovia lanata /Hes-

• Krascheninmkovia lanata /Hes-

perostipa comata Dwarf-shnibland'

perostipa coraata Dwarf-shrubland'

Sands

• Andropogon hallii - Calamovilfa
longifolia Herbaceous Vegetation

Appendix D-2

Ecological Site Types

Plant Associations Found Within Different Precipitation Zones

10 to 14 inch

15 to 19 inch

Silty

• Jimiperus scopulovum / Piptathenim
mtcranthum Woodland

• Pinu^ ponderosa / Pseudoroegneria
spicata Woodland

• Pinu^ ponderosa / Jumpenis horizon-
tally Woodland

• Pascopyrum smithti - Bouteloua
gracilis - Carex fihfolia Herbaceous
Vegetation

• Pseudoroegneria spicata - Carexfih-
folia Herbaceous Vegetation

• Pseudoroegneria spicata - Pascopy-
runj smithii Herbaceous Vegetation

• Artemisia tridentata ssp. wyoraingen-
sis / Pascopyrum smithu Shnibland

• Pimis ponderosa /Carex inops ssp.
heliophila Woodland

• Pinus ponderosa /Pseudoroegneria
spicata Woodland

• Piniis ponderosa / Jumpevus horizon-
tally Woodland

• Pascopyrum smithii - Bouteloua
gracilis - Carex filifolia Herbaceous
Vegetation

• Festuca idahoensis - Carex inops s:^p.
heliophila Herbaceons Vegetation

• Pseudoroegneria spicata - Carex fili-
folia Herbaceous Vegetation

• Pseudoroegneria spicata - Pascopy-
rum smithii Herbaceous Vegetation'

• Artemisia tridentata s^p. wyommgen-
sis / Pascopyrum smithii Shnibland

Clayey

• Artemisia tridentata ssp. wyomingen-
sis / Pascopyrum smithu Shnibland'

• Pascopyrum smithti - Bouteloua
gracilis - Carex filifolia Herbaceous
Vegetation

• Atnplex gardnerii / Pascopyrum
smithii Dwarf-shrubland

• Pascopyrum smithii Herbaceous
Vegetation

• Junipei'us scopulorum /Pseu-
doroegneria spicata Woodland

• Artemisia tridentata s^p. wyomingen-
sis / Pascopyrum smithu Shnibland

• Pascopyrum smithii - Bouteloua
gracilis - Carex fill folia Herbaceous
Vegetation

• Atnplex gardnerii / Pascopyrum
sriuthii Dwarf-shrubland

• Pascopyrum smithn Herbaceous
Vegetation

h^liin Hiliy

Pan Spots

• Carex lanuginosa - Calamagrostis
stricta Herbaceous Vegetation

• Eriogonum pauciflorum - Gutieirezia
sarothrae Badlands Sparse Vegeta-
tion

adlands

Appendix D-3

Ecological Site Types

Phiiit Associations Foun<l Within Different Precipifiition Zones

10 to 14 lacb

15 to 19 inch

Shallow to Gravel

• Pmus ponderosa / Pseudoroegnena
spicata Woodland

• Schizachynum scopanum - Bouteloiia
(curtipendula gracilis) / Carex filifo-
lia Herbaceons Vegetation

• Pmus ponderosa /Pseudoroegnena
spicata Woodland

niin Silty

• Artemisia tndentata ssp wyomingen-
sis / Pascopyrum sntithii Shnib Her-
baceous Vegetation

• Pseudoroegnena spicata - Bouteloua
curtipendula Herbaceous Vegetation

• Artemisia tndentata ssp wyonnngen-
sis / Pascopymm smithii Shrub Her-
baceous Vegetation

• Pseudoroegnena spicata - Bouteloua
curtipendula Herbaceous Vegetation

rhin Sandy

• Hespevostipaconiata - Carex filifolia
Herbaceous Vegetation

• Rhus tnlobata / Pseudoroegnena spi-
cata Shrub Herbaceous Vegetation

• Hesperostipacoraata - Car ex fill folia
Herbaceous Vegetation

• Rhus tnlobata / Pseudoroegnena
spicata Shrub Herbaceous Vegeta-
tion

• Artemisia tndentata ssp. wyomuigen-

• Ai'teuiisia tndentata ssp. wyomin-

sis / Pseudoroegnena spicata Shnib-

gensis / Pseudoroegnena spicata

Very Shallow

land

Shrubland

• Rhus tnlobata / Pseudoroegnena spi-

• Rhus trilobata / Pseudoroegnena

cata Shrub Herbaceous Vegetation

spicata Shrub Herbaceous Vegeta-
tion

Shale

• Atnplex confertifolia -Artemisia tn-
dentata Shiubland

• Atnplex confertifolia -Artemisia tn-
dentata Shrubland

Plant association provisionally assigned to this Ecological Site {and both
precipitation zones); more information needed to confirm placement.

Appendix D-4

Appendix E, Plant Community Descriptions

Plant community descriptions tliat follow are organized witliin the hierarchical framework of tlie Na-
tional Vegetation Standard (FGDC 1997). These description^" exhibit vaiying degrees of completeness.
The most complete plant association descriptions are generally taken ii'oni the hitemational Classifica-
tion of Ecological Communities maintained by NatureServe and updated by state Natural Heritage pro-
grams (NatureServe 2002). A few plant associations recently described by the Montana Natural Heri-
tage Program have been nominated for inclusion into tlie International Classification; tliese associations
are identified by the identifier prefix CEGLMTHP.

Table of Contents

I. FOREST 4

I.A.S.N.b.lO. PINUSPONDEROSA FOREST ALLIANCE 4

Pimis poiulerosa / Prunus xirgifdana Forest 4

n. WOODLAND 6

n.A.4.N.a.8. JUNIPERUS SCOPULORUM WOODLAND ALLIANCE 6

Jumperus scopulorwn / Piptatheniin micranthum Woodland 6

Juniperus scopulorwn / Pseudoroegneria spicata Woodland 7

II.A 4.N.a.32. PINUS PONDEROSA WOODLAND ALLIANCE 8

Pimis ponderosa / Carex inops ssp. /jg/iopM^ Woodland 8

Pimis poiuierosa /Juniperus horizontalis Woodland 9

Pimis ponderosa / Pseudoroe^teria spicata Woodland 10
II.B.2.N.b.4 POPULUS DELTOIDES TEMPORARILY FLOODED WOODLAND

ALLIANCE 11

Populus deltoides / Symphoricarpos occideutaJis \Yood\mid 11

III. SHRUBLAND 13
III A.4.N.a.20. ARTEMISIA TRIDENTATA SSP. WYOMINGENSIS SHRUBLAND

ALLIANCE 13

Artemisia trideutata ssp. Myomingeusis / Pascopyrum smitfiii Shmbland 13

Artemisia tride/ttata ssp. yvyomingeusis / Pseudoroegneria spicata Shmbland 15
III A.4.N.C.2. ARTEMISIA CANA TEMPORARILY FLOODED SHRUBLAND

ALLIANCE 16

Artemisia caiia / Pascopyrwn smithii Shmbland 16
III.B.2.N.d.6. SALIX (EXIGUA. INTERIOR) TEMPORARILY FLOODED

SHRUBLAND ALLIANCE 17

Salix p.x/g^ijg Temporarily Flooded Shmbland 17
III.B.2.N.d.20. SYMPHORICARPOS OCCIDENTALIS TEMPORARILY FLOODED

SHRUBLAND ALLIANCE 18

Symphoricarpos occidentalis Shmbland 18

III.B.3.N.a.l4. SARCOBATUS VERMICULATUS SHRUBLAND ALLIANCE 20

Sarcobahis vermiculatiis / Pseudoroegrteria spicata Shmbland 20

V. HERBACEOUS VEGETATION 22

V A.5.N.a.3. ANDROPOGON HALLII HERBACEOUS ALLIANCE 22
Andropogoft hallii - Calainorilfa longifolia Herbaceous Vegetation 22
Andropogon hallii - Carex inops ssp. heliophila Herbaceous Vegetation 24

V A.5.N.a.ll. CALAMOVILFA LONGIFOLIA HERBACEOUS ALLIANCE 25
C alaaioril fa longi folia- Carex inops ssp. //p/fo;j/»/f7 Herbaceous Vegetation 25

Appendix E-1

QaJamorilfa longifoUa - Hesperostipa comata Herbaceous Ve_Qetation 26
V.A.5.N.C.29. HESPEROSTIPA COMATA - BQUTELOUA GRACILIS

HERBACEOUS ALLIANCE 28

Hesperostipa coinaia - Boitteloua gracilis - CarexfilifoUa Herbaceous Vegetation 28

Hesperostipa comata - Carex fihfoUa Herbaceous VeQetation 29

V.A.5.N.C.27. PASCOPYRUM SMITHII HERBACEOUS ALLIANCE 30

Pascopyrum smithii - Boitteloua gracilis - CarexfiUfolia Herbaceous VeQetation 30

Pascopyrum smitlui Heibaceous Vegetation 33

V.A.5.N.C.20. SCHIZACHYRIUM SCOPARIUM - BOUTELOUA CURTIPENDULA

HERBACEOUS ALLIANCE 34

Schizachyrium scoparium - Boutehua (ctirtipeiidula, gracilis) - Carex fili folia

Herbaceous Vegetation 34

V.A.5.N.C.35. SCHIZACHYRIUM SCOPARIUM HERBACEOUS ALLIANCE 35

Schizachyrium scoparium - Carex i/tops ssp. heUophila Herbaceous Vegetation 35

V.A.5.N.d.8. FESTUCA IDAHOENSIS HERBACEOUS ALLIANCE 36

Festuca idahoeiisis - Carex inops ssp. heliophila Herbaceous Vegetation 36

V.A.5.N.d.22. PSEUD OROEGNERIA SPICATA HERBACEOUS ALLIANCE 36

Pseudoroegneria spicaia - Bouteloua curtipendula Herbaceous Vegetation 36

Pseudoroegneria spicaia - Carex Jilifoha Herbaceous Vegetation 38

Pseudoroegneria spicata - Pascopyrum smithii Herbaceous Vegetation 38

V.A.5.N.i.l8. PASCOPYRUM SMITHII TEMPORARILY FLOODED

HERBACEOUS ALLIANCE 39

Pascopyrum smitliii - Hordeum fubatum Herbaceous Vegetation 39
V.A.5.N.i.ll. SPARTINAPECTINATA TEMPORARILY FLOODED

HERBACEOUS ALLIANCE 40

Spartiua pectinata Western Herbaceous Vegetation 40
V.A.5.N.k.56. CAREX NEBRASCENSIS SEASONALLY FLOODED

HERBACEOUS ALLIANCE 41

Carex fiebrascemis Herbaceous Vegetation 41
V.A.5.N.k.53. CAREX PELLITA SEASONALLY FLOODED HERBACEOUS

ALLIANCE 42

Carex pellita - Calainagrostis stricta Herbaceous Vegetation 42
V.A.5.N.k.61. ELEOCHARIS PALUSTRIS SEASONALLY FLOODED

HERBACEOUS ALLIANCE 43

Eleocharis palustris Herbaceous Vegetation 43
V.A.5.N.k.l3. JUNCUS BALTICUS SEASONALLY FLOODED HERBACEOUS

ALLIANCE 45

Juucus balticus Herbaceous Vegetation 45
V.A.5.N.k.20. PHALARIS ARUNDINACEA SEASONALLY FLOODED

HERBACEOUS ALLIANCE 46

Phafaris aruiidinacea Western Herbaceous Vegetation 46
V.A.5.N.I.6. SCHOENOPLECTUS PUNGENS SEMIPERMANENTLY FLOODED

HERBACEOUS ALLIANCE 47

Schoef top fee tits pungetis Herbaceous Vegetation 47

V.A.T.N.e.ll. ARTEMISIA CANA SHRUB HERBACEOUS ALLIANCE 48

Artemisia caiia ssp. cana / Pascopyrum sinithii Shiiib Herbaceous Vegetation 48

V.A.7.N.Q.5. RHUS TRILOBATA SHRUB HERBACEOUS ALLIANCE 49

Rhus trilobata / Pseudoroegueria spicata Shnib Herbaceous Vegetation 49

Appendix E-2

V.A.7.N.n.l. SARCOBATUS VERMICULATUS INTERMITTENTLY FLOODED

SHRUB HERBACEOUS ALLIANCE 50
Sarcobatiis rermiculaitis / Pascopyniin smithii - (Elyinus fmtceolatus) Shnib

Herbaceous Vegetation 50

VII. SPARSE VEGETATION 52
VII.C.4.N.a.4QQ. ERIQGONUM PAUCIFLQRUM SPARSE VEGETATION

ALLIANCE 52

Eriogonum paiiciflorum - Gutierrezia saroihrae Badlands Sparse VeQetation 52

References 53

Appendix E-3

L FOREST

I.A.8,N,b. Rounded-crowned temperate or subpolar needle-leaved evergreen
forest

LA.8.N.B.10. PINUS PONDEROSA FOREST ALLIANCE

Element Concept

PlNUS PONDEROSA / PRUNUS VIRGINIANA FOREST

Pondeiosa Pine / Clioke Cherry Forest

Suinmai'y: Tliis community type is foimd in the Black Hills and northeast em Rocky Mountains, and western
Gieat Plains escarpments of the United States. It occurs on gentle to moderate (2-40%), nortli-facing slopes and
close to streams. A few stands are on rolling uplands. Tlie soils are sandy loam or loam. Tliis forest community
has a closed canopy of Pimis ponderosa . Seedlings and saplings of Crataegus siiccidenta and Fvaxinus
pennsylvamcQ are often scattered in the understoiy. These species may grow to be mature trees near sti earns.
Tliere are two shrub layers in this community. Tlie most prominent layer is approximately 1 m tall and dominated
by Pnimis virginiana. Amelanchier alnifolia also contributes significantly to this layer. Tlie lower shnib layer is
approximately 50 cm tall. It is dominated by M^^o^ja vepens \^it\\ lesser amounts ofJumpenis communis, Ribes
missowiense, Rosa woodsii, S\-mphoncarpos albiis, and Toxicodendron rydbergn. The diversity of forbs is
moderate, but most of the coverage of the herbaceous layer is provided by graminoids. Apocynum
audj'osaemifohum, Elymus caninus, Carex mops ssp. heliophila, Galium boreale, Schtzachne pmpurascens, and
Maianthemum stellatiim are typical components of the herbaceous layer.

Envli^onment: This is one of the mostmesic ponderosa pine communities. It occurs on gentle to moderate (2-
40%) north-facing slopes and close to streams (Hansen and Hof&nan 19SS). A few stands are on rolling uplands.
Tlie soils are sandy loam or loam.

Vegetadon: Tliis forest community has a closed canopy made up of Pmus ponderosa. Hansen and Hoffman
(19SS) found tliat the basal area ranged from 36.6-63.5 m2/ha in five stands in soutlieastern Montana. Seedlings
and saplings of Crataegus sue cnlenta and Fraxinus pennsylvanica are often scattered in the understoiy. These
species may grow to be mature trees near streams, here are two shrub layers in tliis community. Together they had
an average cover of S7% in five stands sampled by Hansen and Hoffinan (1988). Tlie most prominent layer is
approximately 1 m tall and dominated by Prumis vngimana. Ariielanchier almfoha also contributes significantly to
this layer. Tlie lower slinib layer is approximately 50 cm tall. It is dominated by Mahoma repens with lesser
amounts of Juniperus communis. Ribes raissouriense. Rosa woodsn, 3\-mphoricarpos albus, and Toxicodendron
lydbergii. The diversity of forbs ismoderate^ but most of the coverage of the herbaceous layer is provided by
graminoids. X^ocy/vwm ^n6iosasmifolium, Elymus camnus, Galium boreale, Schtzachne purpurasc ens ^ and
Maianthemum stellatum are typical components of the herbaceous layer.

Dynamics: Signs of fire were noted by Hansen and Hoffinan (1988). Tliis community may be regularly affected
by ground fires.

GRank & Reasons: 03(00-03-16).

Comments: In Nebraska, see comments in Steinauer andRolfsmeier (2000). hi the Black Hills, see MaiTiott and
Faber-Langendoen (2000).

Element Distribution
Range: Tliis community type is found in the Black Hills and northeastern Rocky Moimtains, and western Great
Plains escarpments of the United States, ranging fiom eastern Montana south to western Nebraska.

States/Provinces: MT:S4,NE:S2, SD:S4, WY?

Appendix E-4

Element Sources
Authors: J. Drake. MCS Confidence:! Identifier: CEGL000192

References: Driscoll et al. 1984, Hansen and Hoffman 1988, Hansen et al. 1984, Hoffinan and Alexander 1987,
Pfister etal. 1977, Steinauer and Rolfsmeier 2000

Appendix E-5

IL WOODLAND

n.A.4.N,a, Rounded-crowned temperate or subpolar needle-leaved
evergreen woodland

II.A.4.N.A.8. JUNIPERUS SCOPULORUM WOODLAND ALLIANCE

JUNIPERUS SCOPULORUM / PiPTATHERUM MiCRANTHUMV^OOI>\.A^^

Rocky Mountain Juniper / Little-seed Mountain Ricegiass Woodland

Element Concept
Suinmai'y: This rocky moimtaiu juniper community type is foiiud in the western Great Plaius of the United States.
Stands occur ahnost exclusively on steep (30-70%) uorth-facing slopes. Tlie soils are shallow and poorly
developed; loamy sands and saudy loams predominate. The vegetation stnicture and composition is an evergreen
woodland with moderately open to dense cover ofJumperus scopidorum, Junipenis virgimana, or introgressant
hybrids of the two. Woody species otlier than Jumpenis scopidorum or Jumperus virginiana occur sporadically,
but none achieves prominence. Most of the trees are small (10-20 cm dbh) and few exceed 6 m. Where the
density of the tiee canopy is high, the short-shnib and herbaceous stiata are not well-developed. In more open
places Piptathevum micranthum {= Oijzopsis micvantha) is often abundant. Other common herbaceous species
include Campanula rotundifoha, Galium boreale, aud Mai anthemuni ^tellatum. Mosses and lichens can cover
much of the groimd.

hi Montana, oaiy Jumperus scopulorum is present and dominant. Tliis plant association is best -developed on
sheltered aspects in dissected sedimentary plains. In Powder River County, this plant association is widely-
scattered on escarpments, and dissected teirain along the south end of tlie Powder River.

Envii^onment: Tliis community typically occurs on moderate to steep (16-70%), north-facing slopes, but can
occur on a variety of aspects (Johnston 1987, Von Loh et al. 1999). Tlie soils are poorly developed, shallow,
loamy sands, sandy loams, and clay loams, sometimes witli high gravel content. Tliese woodlands are frequently
associated with outcrops of sandstone (DeVelice et al. 1995) or scoria and clay slopes (Girard et al. 1989).
In Montana, this plant association occurs in a variety of Silty Ecological Sites that are well-drained owing to the
slope and the gully-erosion in tliese settings. This community is best -developed on north aspects.

In Powder River County, this type was foimd on tliin silty ecological conditions. Tliis is consistent with other
Montana state data, with exception of tliin clay conditions noted in Carter County (Vanderhorst et al. 1998).

Vegetation: This woodland community is dominated by ^\\\?M Jumperus scopulorum tiees through most of its
range, and is replaced by J^i'^^/^erus vivgimana and introgressant hybrids in the eastern portion of its range in
Nebraska and South Dakota (Kaul et al. 1983, Von Loh et al. 1999). Acer negurtdo and Fraximis pennsylv am ca
saplings are sometimes foimdin depressions where soil and moisture accumulate. Most of the juniper tiees are 10-
20 cm dbh and 4-6 m tall, but some trees can be up to 30-40 cm dbh. Tlie basal area has been reported at 22-29
m2/ha in North Dakota and up to 22-41 m2/ha in southeastern Montana and northwestern Soutli Dakota (Nelson
1961, Hansen et al. 1984, Hansen and Hoffinan 1988). Tree canopy is moderate to dense, e.g., in North Dakota,
Girard et al. (1989) measured densities of 975 tiees/ha. Where tlie canopy is dense the shrub and herbaceous strata
are poorly developed. Where the canopy is less fiiU, shnibs and herbaceous species are more abundant, e.g. on 7
stands in southwest North Dakota mosses and lichens covered 72% of the ground surface, shrubs covered 17.4%;
graminoids69.1%, andforbs9.4% (Hansen et al. 1984). Among the shrubs that may be found in this community
aiG Jumpej'us comniums, Jumperus horizontahs, small Jumperus scopulorum or Jumperus yirgimana, Mahoma
repens, Dasiphora fruticosa ssp. floribunda (= Pentaphylloides flonbunda) . Prumis vugimana. Rhus tnlobata,
Ribes aureum, Ribes csreum, Rosa woodsu, Symphortcarpos albus^ and Symphoncaipos occtdentalis. Typical
herbaceous species include Pulsatilla patens ssp. multifida (= Anemone patens), Antennana nuavphylla.
Campanula rotundifoha, Carex mops ssp. heliophila, Chenopodmm fi'emontii, Elymus lanceolatus, Elymus
trachycaulus, Galium boreale. Geum triflorum, Koeleria macrantha, Piptatherum micranthum (= Oryzopsis
micrantha)y ?i\id Maianthemum stellatum, Parietaria pensylvanica, and Taraxacum officinale {Hansen et al. 19S4,

Appendix E-6

Hansen andHoffinau 1988).

In Montana, this plant association is distingui^'hed by the palatable bunchgiass Ptptatherum micranthum having tlie
highest graminoid cover at generally 10-30%, the absence or paucity of bluebunch wheatgrass (P^eudoroegnena
spicata)^ high nonvascular cover, and often rich forb diversity and cover (DeVehce et al. 1995, Culwell et al. 1986,
Vanderhorst et al. 1998). Hybrids between Jumperus scopulorum ?iud Jiimpsnis honzontalis have been reported
and may accomitfor the unusual growth form of stands along the Missouri Breaks where trees do not have a
cential axis (Robeits et al. 1979, Heidel 1997).

Dynamics: This plant association is in relatively moist habitat that is not as prone to burning as surrounding
vegetation types, but is higlily flammable when diy. Jumperus scopulorum is readily killed by fire; once ignited
the crowns are almost always completely incinerated.

GRank & Reasons: G3G4 (00-01-31). A number of sites have been impacted by cutting for fenceposts or
railroad ties. Fire suppression may increase the extent of the community within its range.

Comments: Tliis description includes stands with both Jumperus scopulorum and Jumperus virgmiana over a
herbaceous layer with Piptatherum micranthum (= Oryzopsis micrantha). Ptnus ponderosa , if present, is less than
25% tiee canopy cover.

Tliis type ciosGly iatev grades vii^ Jumperus scopulorum / Pseudoroegneria :^ptcata and both may be represented
on tlie same slope or on opposite aspects of the same landform as they were in the dissected terrain along the
Powder River. It often has grassland or steppe openings that condition the levels of overall livestock use. Signs of

fen cepost- cuttings are nbiquitious in the stands and the changes brought on by this history need to be furtlier
addressed in characterizing stand stiiicture.

Element Distribution
Range: Tliis rocky mountain juniper community type is found in the western Gieat Plains of the United States. It
is fonndin the Black Hills and the Badlands of North and South Dakota and Montana, and from the High Plains of
eastern Wyoming eastward to central Nebraska.

In Montana, this plant association is best represented on the open eastern sedimentary plains associated with river
breaks and scattered escarpments. It is sometimes present at the margins of pine woodland landscapes but is not
consistently part of them. Li Powder River Connty, this plant association is present on northeastern escarpments,
and valley segments of the Powder River in the southwestern comer of the County.

States/Provinces: MT:S3,ND:S3,NE:S4S5, SD:SU

Element Sources
Authors: P.L. Hansen, G.R. Hoffman, and A.J. Bjugstad: mod. J. Drake and S. Rolfsmeier, MCS; mod. B. L.
Heidel, MTNHP Confidence: 1 Idfnrtfier: CEGL000747

Referfuces: DeVehce et al. 1995, Diiscoll etal. 1984, Girard et al. 1989, Godfiead 1994, Hansen 1985, Hansen
andHoffinan 1988, Hansen etal. 1984, Johnston 19S7,Kaul etal. 1983, Nelson 1961, Von Loh et al. 1999

JuNiPERUs SCOPULORUM / Pseudoroegneria sp/c>17L4 Woodland
Rocky Mountain Juniper / Bluebunch Wheatgiass Woodland

Element Concept
Suinmai'y:

Envli^oninent: In eastern Montana this community type is commonly found in low to moderate relief rolling
uplands as well as in badland arroyos/draws, often occurring atX\?i{^eiii to Jumperus scopulorum / Achnatherum
hyraenoides (=Oiyzopsis hymenoides) but on warmer exposures (not strictly north-facing) with the same moderate
to steep slopes. Li eastern Montana three of the four sampled stands were on calcareous substrates, though this
habitat type is not confined to these substrates in this region. It has also been recorded for the Beaverhead
Mountains Section occurring on rocky, primarily volcanic substrates with tliin soils; substrate conditions here

Appendix E-7

appear to be the determiniug factors in its occurrence. It is primarily associated with lower tieeliue positions and
slope and aspect are oiily weak determining factors. In eastern Montana, Jump ems scop uloruni / Pseudoroegnena
spicata also has more exposed soil and rock than the associated to Jiimperus scopulorum /Achnatherum
hymenotdss, often exceeding 50%. The same situation often obtains iu western Montana where bare soil and
exposed rock usually constitute 60% plus of the substrate and litter is never more than 20% and adjacent shiublaud
types often have more developed, deeper soils.

Vegetation: As a result of tlie ubiquitous past cutting for fencing, stands of Jimipenis scopulorum /
Pseudoroegnena spicata in eastern Montana are rather open, with coverage of 3 to 12 feet tall Junipenis
scopulorum not exceeding 50%; in tlie Beaverhead Mountains Section, the tiee canopy are also quite open (at most
approaching 30% canopy cover). We speculate tree coverage does not much exceed these figures due to
hmitations of site factors. The higher coverage of shnibs {up to 20 % for Artemisia tridentata ^nd •^Arteraesia
fngida combined) that are reported in noitheastem Montana as opposed to southeastern Montana (Hansen and
Hoffinan 1988) is also attributable to serai conditions. In tlie BeaverheadMoiintains Section, ^? ten ni-m tndentata
ssp. —vaseyana and ssp. wyomingensis, Artemesta frigida, Encamsria nauseosa (=Chrysothamnus nauseosus), and
Chrysothamnus viscidiflorus have the highest constancy but comprise less than 5% cover in the aggregate. The
undergrowth is dominated by graminoids, chief among which and diagnostic of the type is Pseudoroegnena
spicata, always well represented (40% average cover in eastern Montana only 10% in SW Montana). Carex
filifoha and Koelena raacrantha (=FIoelena cnstata) have high constancy and Bouteloua curtipendula is
consistently present in the easteiimiost occurrences of tins type. Forb diversity is moderately high and higher in
western tiian eastern Montana witii not much overlap in higli constancy species between regions; regardless of
location, forb coverage's are generally low» not exceeding 10% except in the most open stands.

Dynamics:

GRaak & Reasons: 04(96-02-01).

Comments:

Element Distribution
Range:
States/Provinces: CO:S2S3, MT:S4, WY:S4

Element Sources
Authors: WCS ConTidence: 1 Identifier: CEGL00074S

References: Bighorn Coal Mine n.d., Bourgeron andEngelking 1994, Brown 1971, Driscoll et al. 1984, Francis
1983, Hansen 1985, Hansen and Hoffinan 1988, Johnston 1987, Strong 19S0, Terwilliger et al. 1979a, Tiedemann
etal. 1987

II.A.4.N.A.32. PINUS PONDEROSA WOODLAND ALLIANCE

PiNus PONDEROSA / Carex iNOPS ssp. heliophila Woodland
Pondeiosa Pine / Sim Sedge Woodland

Element Concept
Suinmai'y: Tliis ponderosa pine / sedge woodland community type is fomidin the Black Hills region, adjacent
Great Plains and northern Rocky M omit a in fi'ont range. Stands occur in the mostuiesic of the habitat types with a
gr a niinoid- dominated ground layer. Tliey are generally found on moderate south- and west-facing slopes in the
western Dakotas, and eastern parts of Wyoming and Montana. Tlie community is dominated by Pinus ponderosa
with occasional Junipenis scopulorum and Quej'cus macrocarpa in the subcanopy. Shrubs are relatively
uncommon in this type. The herbaceous layer is dominated by Carex mops ssp. heliophila^ with inclusions of
Danthoma sptcata, Schtzachynum scopanum, and Pseudoroegnena spicata, generally in areas with more open
canopies.

Envli^oninent: This community is often found on gentle and moderate south- to west -facing slopes (Hansen and
Hoffman 1988, Hoffman and Alexander 1987).

Appendix E-8

Vegetarton: Tlie tree canopy and subcaiiopy are dominated by Finns ponderosa . Jimiperus scopulonim and
QuercHS macrocavpa are occasionally found in the subcanopy. Shnibs are in&eqiient in this type. The herbaceous
layer is dominated by Cavex mops ssp. heliophila (sun sedge), witli inclusions of Danthoma spicata,
Schizachyrium scopanum ^nd Pssudoroegnena spicata^ generally in areas with more open canopies. At Wind
Cave National Park, herbaceous cover is most commonly in the 25-50% range and occasionally greater, with sun
sedge dominant. Other common herbaceous species inciudG Artenust a ludoviciana, Danthoma spicata,
Piptatherum micranthum {= Oryzopsis micvantha), Nassella viridula, and Po a pratensis (H. Marriott pers. comm.
1999).

Dynamics: This type probably develops from little bhiestem prairie as pines become established. Disturbances

such as fire convert stands back to prairies (Marriott andFaber-Langendoen 2000). Tlie canopy in this type is
usually moderately open due to occasional fires, but can become nearly closed in stands where the natural fire
disturbance regime has been disrupted.

GRank & Reasons: G3G4 (00-05-26).

Comments: Tlie stands used by Hoffinan and Alexander (1987) and Hansen and Hoffinan (1988) to document the
Pinus ponderosa /Cavex mops ssp. heliophila Woodland habitat type had very high basal area and densities for a
woodland, possibly due to their sampling procedure. Tlie dense stnicture may have affected tlie fioristic makeup
of the stands. Tliis type is expected to have an open canopy where natural fire distmbances occur.

Element Distribution
Range: This ponderosa pine / sedge woodland community type is fonndin the Black Hills region, adjacent Great
Plains and northern Rocky Mountain fiont range iioiii Montana, Wyoming and South Dakota south to Colorado.

States/Provinces: CO:S2, MT:S3S4, SD:S?, WY:S2S3

Element Sources
Authors: AG. McAdams, WCS Confidence: 1 Identifier: CEGL000849

Referfuces: Bourgeron andEngelking 1994,Driscon etal. 19 S4, Hall 1967, Hall 1973, Hansen 1935, Hansen and
Hoffinan 1988, Hoffinan and Alexander 1976, Hoffman and Alexander 1987, Johnston 1987, Kooiman andLinhart
1986, Livingston 1947, Livingston 1949, Marriott and Faber-Langendoen 2000, McAdams et al. 199S

PiNUS PONDEROSA / JUNIPERUS HORJZONTALIS WOODLAND

Ponderosa Pine / Creeping Juniper Woodland

Element Concept
Suinmai'y: This woodland association has been described from north- cential (Little Rocky Mountains) and the
plains of nortlieastern Montana. All occurrences are below 1160 m (3S00 feet) on calcareous shales and
sandstones of roUing uplands and foothills, generally on slope shoulders. Except for accidentals of Pseiidotsuga
menziesii and veiy scattered Jiiniperus scopulorum. Pi nus ponderosa is the only tree present, witli somewhat
stunted specimens comprising between 40% and 70% canopy cover. Tlie undergiowth is rather depauperate in
species diversity. Jnnipenis honzontalis is always tlie dominant species but varies enormously in cover, fioiii 10-
70% (even greater cover noted in reconnaissance). Jumpevits communis can also attain high cover values but is not
consistently present. Rhus tnlobata v^ndArtemisia tndentata ssp. wyoraingensis are highly constant but seldom
comprise more than 5% cover. There is a stiong difference between the stands in the Little Rocky Mountains^
which have a veiy depauperate graminoid cover, and those of northeastern Montana wherein Pseudoroegnena
spicata ^nd Pascopyrum smithu can attain canopy covers of greater than 30%. Theforb component seldom has
more than a trace amount of any species: tliose with the greatest constancy are Sohdago i^ussounensis, Therniopsis
rhombifolia, and Linum perenne. Structurally and composition ally this association is similar to both Pinus
pondsvosa /Jimiperus communis Woodland (CEGL000859) and Pinus flexilis /Junipei'us communis Woodland
(CEGL000807).

Rank & Rrasons: G3? (00-01-09). Tliis type appears to have a ratlier limited geographic range and few known
occiurences; conversely there is an abundance of potential habitat that could support tliis woodland type. It is
proposed that the rank be changed fiom G3 to G3? Queries of federal agency resource managers in eastern

Appendix E-9

Montana resulted in no positive responses fiom any of them as to having seen this community. With only 6 plots
documented and virtually no reconnaissance information it would seem that this type is rarer than indicated by G3
alone, but indeed it could be more common, thus the ? added to rank.

Comments: Only 6 plots have been documented for this association and hmited reconnaissance notes recorded in
tlie course of the Northern Cheat Plains Ecoregion Rapid Ecological Survey. Tliis type is relatively easily
distinguished from other Pmus ponderosa-domin^tGd types by its abundance oi Jiinipenis honzontalis, though it
conldbe confiised with Finns flexilis / Jiimp ems communis Woodland (CEGL000807) growing on poor sites if one
mshed to judgment on the tree species dominant.

Element Distribution
Range: This woodland association has been described fiom the Little Rocky Mountains in north-central Montana
and the plains of northeastern Montana.

States/Provinces: MT:S3

Element Sources
Authors: S.V. Cooper, WCS Confidence: 2 IdentlTier: CEGL000S60
References: Bourgeron andEngelking 1994, DeVelice et al. 1995, Driscoll et al. 1984, Roberts 1980

PiNUS PONDEROSA / Pseud OROEGNERJA SPICATA WOODLAND

Ponderosa Pine / Bluebunch Wheatgrass Woodland

Element Concept
Summai'y: This ponderosa pine woodland is one of tlie drier ponderosa pine woodlands found in the northern
Rocky Mountains, Liter-Monntains, and extreme northwestern Great Plains of the United States and Canada . It is
found on slopes with coarse soils, often with a high gravel or rock content. Pinus ponderosa is typicaUy tlie only
tree in the overstory, although Jumperus scopulorum may be present in the subcanopy. It forms open to
moderately closed canopies. There are veiy few shnibs. Tlie herbaceous layer is dominated by Pseudoroegnena
spicata. Other species foimd in this layer are Cavexfilifolia, Cavex mops ssp. hehophila, Koslena macrantha,
Achillea millefolium. Bctlsamorhtza sagittata and Hesperostipa comata (= Stipa comata). Bare mineral soil and
exposed rock are common.

Envli^onment: Tliis community occurs mostly on steep southerly aspects. It is found on coarse soils derived from
sandstone, porcillenate, or limestone (Tliilenius et al. 1995). These include sandy alluvium, gravelly or sandy till,
and loams with high stone content. Rock and mineral soil are commonly exposed.

hi Powder River County, MX, this plant association is foimd on ShaUow to gravel, Sandy and Silty Ecological
Sites in both 10-14 and 15-19 inch precipitation zones.

Vegetation: Tliis community is dominated by tlie tree and herbaceous strata. On tliree stands in tlie eastern
portion of its range, Hansen andHoffinan (1988) found that total cover by understoiy strata was 55%. Shrubs
made up only 1.3% of tliis total. Finns ponderosa is often tlie only tiee in the overstoiy. The tiee coverage can
vary from open to moderately closed. In northeastern Wyoming, most of the trees were less than 15 m tall and 60
cm dbh (Thilenius et al. 1995). The herbaceous stratum is also open to moderately dense. Fseudoroegnena
spicata is the dominant species. Other species that are often found in the central and eastern portions of its range
aiGAchillea millefolium var. ocadentahs, Cavexfilifolia, Carex inops ssp. hehophila, Koeleria macrantha, and
Hesperostipa comata (= Stipa comata). In the western portion of tlie range of this community Festuc a idahosnsis
maybe present (Daubenmire 1952). When shrubs are present they typically include F^hus avomatica and,
especially on sandy soils, Ericamena nauseosa (= Chiysothamniis naiiseosus}.

Dynamics: Fire likely occurred at regular inteivals in this type; documentation on fire fieqiiency is not available.
Despite the widely spaced trees and relative paucity, or at least patchy distribution of ftjels, this type experienced
predominantly stand-replacing fire in tiie course of the Alkali Creek burn on the CMR Wildlife Refiige. A more
typical and expected response when these conditions occmin Eire Group Two (warm, diy Finns ponderosa habitat

Appendix E -10

types; Fisher and Claytou 1983) is an undeibiirn or surface fire. The Pirtus ponderosa of this community type iu
the Bull Moimtaiu^ and in tlie Alkah Creek study area generally bore no fire scars. This observation probably
reflects the light fijels condition for this type and may also point to Ihe exceptional Alkali Creek Fire conditions.
Tlie lack of Juniperus scopulorum in this type may be attributable to past fires killing this species and leaving the
Finns ponderosa ov erst oiy intact; this scenario has been documented by Culwell et al. (1991) in theBuU
Mountains of central Montana.

GRank & Reasons: G4 (96-02-01).

Element Distribution
Range: Tliis ponderosa pine woodland is one of tlie drier ponderosa pine woodlands found in the northern Rocky
Mountains, Litermoiintains, and extreme northwestern Great Plains of the United States and Canada, extending
fi'om the Black Hills of South Dakota and Wyoming west to Oregon, Washington, and British Columbia.

States/Provinces: BC:S2S3, ID:S3, MT:S4, ND:S2S3?, OR:S2, SD:S4, WA:S1, WY:S3?

Element Sources
Authors: Drake, J. F., WCS; Heidel, B. L. MTNHP Confidencf : 1 Identifier: CEGL000865
References: Bourgeron andEngelking 1994, Clausnitzer and Zaniora 1987, Cooper andPfister 1985, Cooper et
al. 19S7,Daubenniire 1952, Daiibenmire 1970, Daiibenmire and Daubenmire 1968, Driscoll et al. 19S4,Hall 1973,
Hansen and Hoffinan 1988, Hansen et al. 1984, Hoffinan and Alexander 1976, Johnson and Clausnitzer 1992,
Johnson and Simon 19S5, Johnson and Simon 1987, Johnston 19S7, Jones 1992b, McAdanis et al. 1998, McLean
1970,Pflster et ai. 1977, Steele et al. 1981, Teiwilhger et al. 1979a, Thilenius etal. 1995, Williams and Lillybiidge
1983, WiUiams and Lillybiidge 1985,Zamora 1983

n.B.2.N.b. Temporarily flooded cold-deciduous woodland

II.B.2.N.B.4. POPULUS DELTOIDES TEMPORARILY FLOODED WOODLAND
ALLIANCE

POPUL US DEL TOIDES / SYMPHORICARFOS OCCWENTALIS WOODLAND

Plains Cottonwood / Western Snowberry Woodland

Element Concept
Suinmai'y: Tliis riparian woodland community is fomidin the northwestern Gieat Plains of the United States on
medium to coarse-textured alluvial soils on tlie floodplains of major rivers. Tlie floodplains are both seasonally
inundated and siibiriigated. It is found more rarely at higher elevations in the mountains of eastern Wyoming and
western South Dakota. Tliis community is dominated by a single deciduous tiee species, Popnlus deltoides. In
some stands other species, such as^lcer negundo and Fraxinus pennsylvamca^ may contiibute to the canopy. Tlie
tallest trees exceed 15 m. The shrub layer is typically 0.5-1 mtall. It ii^ tXoimw^ttdhy Symphoncarpos
occidentalis and commonly 'niQhxdt^ Jiimpenis scopulonim ?indRosci spp. Li Wyoming, Encamena nanseosa (=
Chrysothammis nanseosus) is present and increases with heavy grazing. The herbaceous layer usually includes
Pascopyrum smtthti. Weedy species such as Melilotus officinalis. Taraxacum officinale, and Poa secimda are very
common, especially in the presence of grazing. Maianthcmum stellatum is abimdant only where grazing is absent.

Envii^onment: Tliis community is found on medium to coarse-textured alluvial soils on the floodplains of major
rivers. The floodplains are both seasonally inundated and subirrigated (Tliilenius et al. 1995). Tlie meandering
erosional and depositional pattern of rivers maintains and influences this community along rivers (Hansen et al.
1990). It is rarely found at higher elevations in the mountains of eastern Wyoming and western South Dakota
(Johnston 1987).

hi Montana, fliis plant association occurs on major river systems of the eastern plains, with a flood cycle driven by
mountain run-off and vegetation succession linked to intact hydrological processes. In Powder River County, this
plant association is foimd in Riparian subiirigated Ecological Sites along the Powder and Little Powder Rivers.

Appendix E -11

Vegetation: Tliis community is typically dominated by a single deciduous tree species, Popidus deltotdes. lu
some stands other species, such as^lcer negimdo and Fraxinus pennsylvamca^ may couhibute to the canopy. Tlie
tallest trees exceed 15 m. Popidus deltotdes is a pioneer species that requires moist, sparsely vegetated alluvium to
become established from seed; therefore stands of this community maybe considered serai, bntthe stage is long
persistent (up to 100 years) (Girard et al. 19S9). Tlie slirub layer is typically 0.5-1 m tall. It is dominated by
S\-mphoricarpos occidentalis and commonly includes Jj;??jperf;j scopulonim ?[nd Rosa spp. In Wyoming,
Encamena nauseosa (= Chiysothamnus nauseosus) is present and increases with heavy grazing (Thilenius et al.
1995). The herbaceous layer usually includes Pascopyrum snuthu and Elyraus trachycaulns. Weedy species such
as Ctrstum arvense. Mehlotiis officinalis, Taraxacum officinale^ and Poa secunda are veiy common, especially in
the presence of grazing (Jones and Walford 1995, Tliilenius et al. 1995). Maianthemuni stellatum is abimdant only
where grazing is absent.

In Montana, stands are typically heterogeneous in vegetation age and structure as weU as microtopography,
because of tlie small-scale patterns of alluvial deposition and erosion operating over the years. In Powder River
County, Cottonwood communities are represented by all serai stages, from seedlings up to trees greater than 18
inches circumference. The latter stands are widely spaced, with Arteraisi a cana establishment if theunderstory is
intact. In the study area, Symphoncarpos ocadentalis was typically present, but was there was not a distinct
shrub-layer dominant. The dominant grass was Pascopyrum snnthu, followed by Nassella vindida, and replaced
by Poa pratensis under disturbance. Otlier characteristic species include Rosa woodsu, Elymiis canadensis and
such generalists ^sAchillea millefolium. Tliere is widespread invasion by Euphorbia ssula, which has become
locally abundant in many stands. Tamegrasses have been seeded or accidentally intioduced into some stands,
induing Agropyron repens and Bvomis mevmis.

Dynamics: This type is found closest to the river on young, unstabihzed floodplains, where it colonizes the
freshly deposited alluvial substiates on the meanders of the streams and rivers. Proceeding away from the river,
otlier later successional stages may include Populus deltotdes / Fraxinus pennsylvamca Forest (CEGL00065S) and
Fraxinus pennsylvamca - (Ulraus americana) / S\-mphoricarpos occidentalis Forest (CEGL00208S). As the sti'eam
continues to move away from the more recent deposits, the stand may eventually succeed to the Fvaxtnus
pennsylvamca type, a process that could take 100 years {Girard et al. 1989).

In Montana, the climate is too diy for succession to the Fvaxtnus pennsylvamca type. Decadent stands may
succeed io Artemisia cana (Boggs 19S4).

GRank & Reasons: G2G3 (9S-06-22). The total number of occurrences is unknown. Tliirteen have been
documented in North Dakota, where the commimityis ranked S1S2?. Although no other occurrences have been
doaimented, the community is also reported from Wyoming (S2), Colorado (S2) and may occur in South Dakota
(SP). It is found in three nortliern Great Plains ecoregional sections. The community occurs on medium- to
coarse -textured soils on tlie floodplains of major rivers.

Comments: Concept of the type may have come from Thilenius and Brown (1990). hi eastern Montana, Hanson
et al. (1990) describe a Populus deltotdes I Symphoncarpos occidentalis type as a grazing-induced stage of the
Populus deltotdes I Cornus sericea type. This contrasts with information from Wyoming, where Tliilenius et al.
(1995) found that Symphortcaipos occidentalis decreases with grazing and Chrysothamnus nauseosus increases.

Element Distribution
Range: Tliisripaiian woodland community is found in floodplains of the northwestern Great Plains of the United
States, ranging from North Dakota to Colorado.

States/Provinces: CO:S2, MT:S2S3,ND:S1S2?, SD?, WY:S2

Element Sources
Authors: J. Drake, MCS: mod. B. L. Heidel, MTNHP Confidence: 1 Identifier: CEGL000660
References: Boggs 19S4, Driscoll et al. 19S4, Girard et al. 19S9, Hansen et al. 1990, Johnson et al. 1990a,
Johnston 19S7, Jones 2001, Jones and Walford 1995, Kartesz 1999,Kittel et al. 1999, Tliilenius 1970, Thilenius
andBrown 1990, Thilenius and Smith 1985, Thilenius et al. 1995

Appendix E -12

III. SHRUBLAND

in.A.4.N.a. Lowland microphyllous evergreen shrubland

III.A.4.N.A.20. ARTEMISIA TRIDENTATA SSP. WYOMINGENSIS SHRUBLAND
ALLIANCE

Artemisia tridentata ssp. wyomingensis I Pascopyrum smithii Shrubla^^^
Wyoming Big Sagebnish / Western Wlieatgiass Shnibland

Element Concept
Suinmai'y: Tliis Wyoming big sagebrush type is found throughout the northern Gieat Plains and adjacent basins,
Black Hills, and Rocky Mountains of the United States. Stands occur on gently rolling uplands or upper parts of
stieani terraces and drainageways. Drier examples may be on more exposed slope positions. Soils are moderately
deep clays, clay loam, silt loam and loam. Soil moisture conditions are relatively mesic. Soil pH ranges from 5.8
to 7.8. "Hie vegetation contains an open short-shrub layer, approximately 0.5 m tall, dominated by microphyllous-
leaved shrubs, and a dense herbaceous layer dominated by medium-tall graminoids. Shrub cover averages between
15% and 30%. Artemisia tridentata ssp. wyomtngensis dominates the shnib layer. Tlie dense herbaceous layer has
a canopy cover of over 75%. Pascopyrum smtthti is the leading dominant. Important associates include Koeleria
macrantha, Poa secimda, and Nassella vindula (= Sttpa viridida). hi diier or more heavily grazed phases,
Bouteloua gracilis, Hesperosttpa comata (= Stipa comata)^ and Carex filtfoha may be more common, along with
the succulent Opimtta polyacantha. Forbs contribute low cover, often less than 10%, and are typically of low
constancy. More constant species (>50%) mcXwd^ Artemisia fngida, Sphaeralcea coccinea, and Vicia amei'icanci.
Grassy leaf litter covers over 75% of the ground; stones and bare soil comprise the remainder. Nonvascular plants
are rare.

Envli^onment: Stands occur on gently rolling uplands or upper parts of stream terraces and drainageways. Diier
examples may be on more exposed slope positions. Soils are moderately deep clays, clay loam, silt loam and
loam. Soil moisture conditions are relatively mesic. Soil pH ranges from 5.8 to 7.8 (Hirsch 19S5, Hansen and
Hoffinan 1988, Tliilenius et al. 1995).

In Montana, this widespread plant association assimies many positions and patterns depending on environmental
and perhaps historical context. It prevails across Beaipaw Shale in the Missouri River drainage (DeVelice et al.
1995, Jorgenson 1979, Heidel 1997) and Beaipaw shale of extreme southeastern Montana in Carter County
(Vanderhorst et al. 199S). Tlie pH of soils with tliis plant association in Carter County ranged from 4.9-S.O. It is
present at some scale in all landscapes compiised of entisol-aiidisol soil complexes. Over most of the shale plains
in Powder River County, it is concentrated on the steeper slopes (greater than 8%) giving way to grassland on
gentler slopes. Tliis plant association is primarily east of the mountains, but is also documented on alluvial terraces
of southwestern Montana (Cooper et al. 1995). FinaUy, it is found in smaU grassland panspots at the extreme
eastern end of the state.

In Powder River County, tliis plant association is found in Thin Si Ity Ecological Sites, 10-14 in. precipitation zone.
It is consistently found on steeper slopes throughout much of the County. It is not limited to steep slopes in all set-
tings, and prevails at the exheme southwestern border of the county on Silty ecological sites, where elevation is
higher. This is the case in the Ashland Dishict of Custer National Forest, where soils supporting this plant associa-
tion are characterized as loams and sandy loams (Hansen and Hoffman 19SS) that seem to fall within the "Silty
ecological site" definition.

Vegetation: The vegetation contains an open short-shnib layer, approximately 0.5 m tall, dominated by
microphyllous-leaved slinibs, and a dense herbaceous layer dominated by medium-tall graminoids, Shnib cover
averages between 15 and 30% (Hirsch 19S5, Hansen and Hoffinan 1988, Tliilenius et al. 1995). Artemisia
tridentata ssp. wyommgensis dominates the shnib layer. Tlie dense herbaceous layer has a canopy cover of over
75%. Pascopyrum smithii is the leading dominant. Important associates include Koelena macrantha, Poa
secunda, and Nassella viridula (= Stipa vindula). In drier or more heavily grazed phases, Bouteloua gracilis,
Hesperostipa comata (= Stipa comata), and Carex filifolta may be more common, along with the succulent

Appendix E -13

Opuntia polyacantha. Forbs contribute low cover, often less than 10%, and are typically of low constancy. More
constant species {>50%) inchidG Artemisia fiigi da. Sphaeralcea coccmea, and Vicia araencana. Grassy leaf litter
covers over 75% of the ground; stones and bare soil comprise the remainder. Nonvascular plants are rare (Hirscli
19S5, Hansen and Hoffman 1938, Thilenius et al. 1995).

In Powder River County, the cover of Pascopyrum ^mithu was high in pineland openings, up to 60% cover^ while
on the open plains was more typically less than 30% cover and codominant with CavexfilifoliQ, Poa secunda, and/

or Koelena macrantha. Commonly associated species iiiQlvidt Artemisia fngida, Achillea millefolium , Agoseris
glauca. Allium textile. Antenna fia paw i folia, Comm^wd^a umbellata, Gutieirezia safothrae , Opuntia polyacantha.
Phlox hoodii, and Vicia amencana. A particularly rich stand in the western end of the county included species that
were scarce or absent elsewhere, including Calochovtus nuttalhi. Besseya wyomingensis, Linura lewisn^ and
Nassella vindula. Under heavy grazing pressure, the cover of exotic andincreaser species like Bvomus japomcus,
Hedeoma hispida, Plantago patagonica, and Vulpia octofloi'a increases gi'eatly.

Dynamics: Taylor and Hoist (1976) refer to an ''upland praririe sagebrush ecosystem" of the Ashland District and
note that this sagebrush ecosystem overlaps strongly with upland grassland, appearing as an edaphic difference in
places, and as a grazing disclimax in others. Tliis dual nature of this sagebrush plant association was evident in the
study area, with its status as an edaphic phenomenon indicated by the many areas in good condition. In
southwestern Montana, this plant association may be a grazing disclimax (Cooper et al. 1995). See Cooper and
Jean (2001) for a discussion of fire succession in tlie veiy i^mi\»E Artemisia tridentata ssp. wyomingensis / Elymus
lanceolatiis association.

Artemisia tridentata ssp. wyomingensis is killed witliin prairie dog towns. In Powder River County, vegetation
sampling was conducted on a bench along Buffalo Creek in what appeared to be a long-abandoned prairie dog,
even though there were no signs of burrow mounds remaining. Elsewhere on the b^ii\:\i^ Artemisia tridentata ssp.
wyomingensis dominated in identical settings. In the abandoned prairie dog town, tliere was 50% cover of
Pascopynim sraithii and 10% cover of both Poa secunda ?[nd Bromus japonicus^^i^h. high fitter accumulation
(greater than 60%). Perhaps the ferfifizing and churning infiuence of the prairie dogs heightened productivity and
impeded re-establishment oiArtemisia tridentata ssp. wyomingensis in the high vegetation and/or high litter cover.

GRank & Reasons: G4 (94-02-23).

Higli-ranked species: The complex vegetation mosaic patterns of this plant association within grassland and
sparsely vegetated outcrops lends habitat diversity that has high wildlife values for big game and upland bird spe-
cies.

Comments: Tins plant association is often part of a continuous gradient with the Pascopyrum smithii - Bouteloua
gracilis - Carex fill folia Herbaceous Vegetation. Tlie cover of Artemisia tridentata ssp. wyomingensis is also
variable within stands, clustered around the cut-off point used in differentiating shrublandfiom shrub herbaceous
vegetation, rather than centered greater or less than this point representing a cover value that can be discerned in
remote sensing. Tims, the cover values used to define it are problemmatic.

Many of the same plant association classification questions associated with the Pascopyrum sraithii - Bouteloua
gracilis - Carex fill folia Herbaceous Vegetation are also present for this plant association: 1) the inter change ability
and ecological equilivence of Pascopyrum smithii znd Elymus lanceolatus and the similar needlegrass species-pair
has not been analyzed in detail. They sort by latitude in their distribution and their tendency to have different
environmental modes where they occur together waiiants extended documentation. We did note tiiat Elymus
lanceolatus is uncommon in Powder River County compared to Pascopyrum smithii; the former species is most
common on overflow outwashes and panspots in tiie County. However, Elymus lanceolatus appeared to be the
dominant or codominant in at least some of the Carter County vegetation study sites (Vanderhorst et al. 1998) and
further investigation is needed into their ecological equivalency. 2). The question of delimiting the Pascopyrum
smithii dominance fiom the Hesperostipa comata - Bouteloua gracilis dominance becomes secondary where
Artemisia tridentata ssp. wyomingensis cover is high. The fine textured soils preclude much Hesperostipa comata
in the study area. 3). There are different co-dominants with Pascopyruni smithu. with or without Bouteloua
gracilis, Carex fill folia, Buchloe dactyloides, and Poa secunda. Given the current concept of this type, they all fit

Appendix E-14

within the type» butuot all of their environmental characteristics fit. Tlie codominance of Buchloe dactyloides v/ith

Pascopyvum srattini inArtemisia tndentata ssp. wyommgensis shnibland, as documented on BLM -administered
lands in much of Powder River County, has not been well -documented in the nortliern Gieat Plains.

Element Distribution
Range: Tliis Wyoming Big Sagebrush type is found throughout the nortliern Great Plains and adjacent basins,
Black Hills, and Rocky Mountains of the United States, parti ailarly in Colorado and Wyoming.

hi Montana, it inmost extensive on shale plains in counties along tlie Missouri River (DeVelice et al. 1995), as
weU as those of Carter County in the southeastern corner {Vanderhorst et al. 1998). But it is present throughout
eastern Montana where there are fine-textured entisol and aridisol soils, as found on Ashland and Sioux Distiicts of
Custer National Forest (Hansen and Hoffman 19SS). In Powder River County, this plant association is present
everywhere the topography is dissected. It is especially extensive in the extreme southwestern comer of the
county.

States/Provinces: CO:S3S4, MT:S?,ND?, WY:S?

Element Sources
Authors: D. Faber-Langendoen, WCS; mod. B. L. Heidel, MTNHP Confidence: 2 Idfnrtrier: CEGL001047
Referfnces: Baker 1932b, Baker 19S3c, Baker and Kennedy 1985, Bear Creek Uranium Mine Application n.d,
Bourgeron andEngelking 1994, Cooper et al. 1995, Cooper and Jean 2001, Cotter -Ferguson Project n.d., DeVelice
etal. 1995,Driscoll et al. 1984, Earth Resource Technology n.d., Ellis and Hackney 1981, Francis 1983, Hansen
andHoffinan 1988, Hansen etal. 1980, Hansen etal. 1984, Hirsch 1985, Keamnierer 19S7, Skull Point Mine
Application n.d., Skull Point Mine Permit Renewal n.d., Stiong 1980, Sweetwater Uranium Project 1978, Thilenius
etal. 1995,Tiedemann etal. 1987, Vanderhorst et al. 199S

Artemisia tridentata ssp. wyomingensis / Pseudoroegneria spicata Shrubland
Wyoming Big Sagebrush / Bluebunch Wheatgrass Shrubland

Element Concept
Suinmai'y: Tliis is a widespread Wyoming Big Sagebrush shrub type, extending fiom the western side of tlie
Great Plains on the east to British Columbia on the west, and south as far as northern Nevada. Stands of this type
occupy loamy soils (often with coarse fiagments) derived fiom a variety of parent materials, on middle and lower
slopes and in draws. Shrubs are dense and form a canopy witli at least 25% cover. Artemisia tndentata ssp.
wyommgensis contributes the most cover to the shrub layer and is often the only shrub present. Tlie heiglit of the
sagebnish ranges fiomabout35 cm tall in the eastern part of the range toabout 1 m tall in the western part.
Chrysothammis spp. often are present as well. Pseudoroegneria sptcata contributes more cover to the herbaceous
layer than does any other native species, and Poa secunda usually is present. Stands in the eastern part of the
geographic range often include Gutterrezia sarothrae , Artemista fngida, Bouteloua gracilis^ and Koelena
macrantha. Many stands of tliis community may result fi'om grazing in stands of Artemisia tridentata ssp.
wyomingensis / Pseudoroegneria sptcata Shrub Herbaceous Vegetation (CEGL001535). Grazing increases the
cover and density of shrubs and often decreases the cover of grasses, especially of Pseudoroegneria sptcata.
Stands no doubt exist, though, that do not result ftom grazing. Such stands are likely found in diaws and other
places on the landscape where soil moisture is sufficient to support a dense shrub canopy, and may represent only a
smaU area on the landscape.

Envli^onment: Stands of tliis type occupy loamy soils {often witli coarse fragments) derived from a variety of
parent materials, on middle and lower slopes and in diaws. The close relationship between this association and

Artemisia tndentata ssp. wyomingensis / Pseudoroegnena spicata Shrub Herbaceous Vegetation (CEGL001535)
suggests that stands of this type occupy loamy soils (often with coarse fiagments) derived ftom a variety of parent
materials, on middle and lower slopes and in diaws.

Vegetation: Tliroughoiit the geographic range of this type,^^^^^^^^^ tndentata ssp. wyomingensis dominates a
shrub layer tliat has at least 25% canopy cover. Rabbitbrushes (Chrysothammis spp.) often are present as well.
Psendovoegnena spicata contributes more cover to the herbaceous layer than does any other native species, and
Poa secunda usually is present. Stands in the eastern part of the geograpliic range often include Gutierrezia

Appendix E -15

sarothrae, Artemisia fngida, Bouteloua gracilis, ^nd Koeleria macrantha. The heiglit of the sagebrush ranges
from about 35 cm tall in the eastern part of the range to about 1 m tall in the western part (Hirouaka et al. 19S3).

GRank & Reasons: G5? (96-02-01).

Comments: Many stands of this association maybe derived by grazing of Artemisia tridentata ssp.
wyommgensis / Psendoroegnena spicata Shrub Herbaceous Vegetation (CEGL001535). It maybe preferrable to
first combine these two types, and then split them geographically. Tlie occuirences from the Great Plains west as
far as northwestern Colorado, western Wyoming, and western Montana might belong to one type characterized by
the presence of Bouteloiia spp., Carexfilifoha, Koeleria macrantha, Gutisrrezia sarothrae, Artemisia fngida, and
Opuntia polyacantha^ and by the absence of Achnatherum thurberianum (= Stipa thiirberiana) . The occuiiences
fi'om southern Idaho, nortliern Nevada, eastern Oregon, eastern Washington, and British Columbia could belong to
a different type characterized by the presence of Achnatherum thurberianum, and by the absence of the other
species listed above. Tlie separation between these two types probably would occur in Idaho. Additional research
will be required to clarify this issue.

Element Distribution
Range: Tliisis a widespread Wyoming Big Sagebrush shnib type, extending fiom the western side of the Gieat
Plains on tlie east to British Columbia on the west, and soutli as far as northern Nevada.

States/Provinces: BC:S2, CO:S3?, ID:S?, MT:S5?, ND:S2S3?,NV:S?,UT:S4S5?, WA:S?, WY:S?

Element Sources
Authors: B. Johnston, mod. D. Fab er-L an gen do en, WCS Confidrnce: 2 Identifier: CEGL001009
Referfnces: Blackburn 1967, Blackburn et al. 1968a, Biackbiun et al. 196Zb, Blackburn et al. 1969a, Blackburn
et al. 1969c, Blackburn et al. 1971, Bourgeron andEngelking 1994, Brotherson and Brotherson 1981, Cooper et al.
1995, Daubenmire 1970, DeYelice et al. 1991, Driscoll et al. 19S4,Hail 1973, Heinze et al. 1962, Hironaka et al.
1983, Johnston 19 87, Knight et al. 1987, Lewis 1975, McLean 1970,Moretti 1979,Moretti and Brotherson 1982,
Mueggler and Stewart 19S0,Pouhon 1955,Tisdaie 1947

in.A.4.N.c. Temporarily flooded microphyllous shrubland

III.A.4.N.C.2. ARTEMISIA CANA TEMPORARILY FLOODED SHRUBLAND
ALLIANCE

Artemisia cana / Pascopyrum smithii Shrubland

Silver Sagebrush / Western Wheatgrass Slirubland

Element Concept
Suinmai'y: This silver or coaltowu sagebnish shrubland is foiiud in Ihe northwestern Great Plains and Rocky
Moimtaius of the western United States. Stands occur on flat alluvial deposits on floodplains, terraces or benches,
or alluvial fans. The soils are moderately deep to deep and either silt loam, clay loam, or sandy loam. Flooding
may occur periodically aud this teuds to retard soil development. Tliis community is dominated by a combination
of shrubs and graminoids. Tlie total vegetation cover is moderate. The tallest and most conspicuous stratum in
fliis community is a shrub layer that is usually 0.6-1.2 m. Artemisia cana is tlie dominant in this layer and may be
?ii^i^o\i\^^mtdhy Symphoricarpos occidentalis. Also present are shorter shrubs such 9^^ Artemisia frigida,
Kraschemnnikovia lanata, Rosa woodm, and Gutierrezia sarothrae. Tlie most abundant graminoid is Pascopyrum
smithii. This species is typically 0.5 -1.0 m tall. It is often accompanied by Nassella viridida and sometimes
Koelena macrantha, Poapratensis, ^nd He sperostip a coraata {= Stipa comata). B outGlona giacilis is the most
abundant short graminoid. Typical forb constituents of this community aie Achillea millefolium, Gaura coccinea,
^haeralcea coccinea, and Lactuca tatarica var. pulchella.

Envli^onment: Tliis community occurs on flat alluvial deposits on floodplains, terraces or benches, or aUuvial
fans. Tlie soils are moderately deep to deep (USPS 1992) and either silt loam, clay loam, or sandy loam (Johnston
1937, Hansen and Hoffinan 19S8). Tlie soils may have moderate salt content (Hanson and Whitman 1938).
Flooding occurs periodically and this tends to retard soil profile development (Hirsch 19S5).

Appendix E -1(5

In Powder River County, tliis plant association is found on Overflow Ecological Sites in the 10-15 and 15-19 inch
precipitation zones. It is the prevailing vegetation along major river valleys.

Vegetation: This community is dominated by a combination of shrubs and graminoids. Tlie total vegetation cover
is typically moderate, but depends on frequency of flooding. Tlie tallest and most conspicuous stratum is a shmb
layer that is usually 0.6-1.2 m (Hansen and Hoffinan 19 SS). Li 14 stands in western North Dakota shrubs averaged
2S% canopy cover, graminoids 59%, andforbs 2% (USFS 1992). Stands in Nebraska often have less than 15%
cover. Tlie variation in soils within and between stands of this commimity results invariable species composition.
Artemisia cana is tlie dominant shrub. Symphoncarpos occtdentahs is fieqiiently present. Tliere are also shorter
shrubs such ?i^ Artemisia fi'igtda, Krascheninmkovia lanata, Rosa woodsn^ and Gidierrezia sarothrae. Tlie most
abimdant giaminoidis Pascopyriim smithii. This species is typically 0.5-1.0 m tall. It is often accompanied by
Nassella viridula and sometimes Floeleria macrantha, Poa pratensis^ und Hesperostipa comata (= Stipa con\Qta}.
Bouteloua gracilis is the most abundant short giaminoid. Typical forb constituents of this community ^t Achillea
millefoliHTd , Gaiira coccmea, Sphaeralcea coccinea^ and Lactnca tatarica var. pidchella.

Dynamics: Periodic flooding occurs in many stands of this community.

GRank & Reasons: G4 (96-02-01).

Comments: See Steinauer andRolfsmeier (2000) for a description of the stands in Nebraska.

Element Distribution
Range: This silver or coaltown sagebnish shrubland is found in the northwestern Great Plains and Rocky
Mountains of the western United States, ranging floni Montana and North Dakota, south to Nebraska.

States/Provinces: MT:S4,ND:S2S3?,NE:S?, SD:SU

Element Sources
Authors: Drake, J. F., WCS; mod. B. L. Heidel, MTNHP Confidence: 1 Identifier: CEGL001072
References: Bourgeron and Engelking 1994, DriscoU et al. 19S4, Hansen and Hof&nan 19SS, Hansen et al. 1984,
Hansen etal. 1991, Hansen et al. 1995, Hanson andWliitman 193S,Hirsch 1985, Johnston 19S7, Nelson 1961,
Steinauer and Rolfsmeier 2000, USFS 1992

in,B,2,N,d. Temporarily flooded cold-deciduous shrublaiid
III.B.2.N.D.6. SALIX (EXIGUA, INTERIOR) TEMPORARILY FLOODED
SHRUBLAND ALLIANCE

Salix ExiGUA Temporarily Flooded Shrubland
Coyote Willow Temporarily Flooded Slimbland

Element Concept
Summai'y: Tliis willow shrubland commimity is foimd along rivers and streams al lower elevations tliroughout
tlie nortliwestern United Stales and Great Plains. Tliis type is an early siiccessioual stage that occurs on recently
flooded riparian areas. Slands occur most commonly on alluvial sand, but sill, clay, or gravel may also be present.
Salix exigua is Ihe dominant canopy species (Salix interior or intermediates of the Iwo willow species may be
present in the eastern part of the range). It cauform dense slands up to 4 m tall, but there are often pa Iches where
tlie shrub layer is absent Seedlings and small saplings of Popidus deltoides T^ndSahx amygdaloides maybe
present. Tlie herbaceous cover is sparse to moderate, but rarely exceeds 30%. Species present include Cenchrus
longispwiiis , Polygonum lap athi folium , Schoenoplsctus ctmericanus {= Scirpiis araericamis), Triglochin n^aritima^
?i\id Xanthium stuimanuni. The composilion of Ihis community, especially the herbaceous layer^ varies fi'om year
to year with succession or renewed disturbance.

Envli^onment: Tliis community is found on recentiy deposited or disturbed alluvial material. Tlie parent material
is alluvial sand, although silt, clay, or gravel may be present. Soil development is poor to absent.

Appendix E -17

Vegetation: Tliis community is dominated by shrubs, generally between 2 and 4 m tall. The most common of
tliese is Saltx exigua (Saltx interior or intermediates of the two willow species may be present in the eastern part of
tlie range). Sahx irrorata and saplings of Popuhis deltoides or Saltx amygdaloides are also &equently fonnd in the
shrub layer. This stiatiun can have moderate to high stem density in tlie community as a whole. Tlie species in the
shrub layer do not form a closed canopy, allowing significant hght to reach the ground layer. Tliere are often
patches where the shrub layer is absent. Tlie herbaceous cover is sparse to moderate, but rarely exceeds 30%.
Older stands and places with less competition ftom the shrubs have greater herbaceous cover. The composition of
the herbaceous layer can vary greatly. Species that are often found in this commimity are Cenchms longispmus.
Polygonum lap athi folium , Schoenoplectus americanus (= Scirpus amencanus), Triglochin mantima, and
Xanthium strumarium.

Dynamics: This type originates after flash floods that create new deposits or scour existing alluvial material. This
community is a primary or early secondaiy community and requires floods to create new areas on which it can
develop. Once established, this commimity may not exist for more than 10-20 years before it is replaced by a later
serai stage.

GRank & Reasons: G5 (99-05-06)

Comments: Tliis type may be an early successional shrubland that develops into Sahx exigiia I Mesic Graminoids
Shmbland (CEGL001203), or the two types may be essentially synonymous. Tliis plant association occupies a
wide geographic range. Tlie range of this type was reviewed and it was split into eastern, Sahx interior
Temporarily Flooded Shmbland (CEGL008562), and western components. Tlie western stands may all be
composed of jSa^^x exigua (sensu stncto) and Great Plains stands may contain either Salix exigua, Salix interior^ or
intennediates of the two willow species, the Saltx exigua being an entirely Great Plains and eastwardly distributed
species (Kartesz 1999).

Element Distribution
Range: Tliis sandbar willow shmbland community is found along rivers and streams at lower elevations
tliroughout the nortliwestern United States and Gieat Plains, ranging sporadically fiom Oklahoma northwest to the
Dakotas and Manitoba, and west to Washington. Part of this type's former range in the Great Plains and eastward
is actually occupied, at least in part, by Salix interior [see Saltx interior Temporarily Flooded Shrubland
(CEGL00S562)].

States/Provinces: ID:S3?, MB:S?, MT:S5,ND:S?,NE:S4S5, OK:S?, OR:Sl, SD:S2, WA:S?, WY:S3Q

Element Sources
Authors: I.E. Drake, WCS Confidence:! Identifier: CEGL001197

References: Bellah and Hiilbert 1974, Boiirgeron and Engelking 1994, Driscoll etal. 1984,Evenden 1990, Foti et
al. 1994, Hansen et al. 19 89, Hansen et al. 1991, Hansen etal. 1995, Hoagland 1998c, Hoagland 2000, Kartesz
1999, Kittel and Lederer 1993, Kovalchik 19S7, Phillips 1977, Steinauer 1989, Steinauer and Rolfsmeier 2000,
Wilson 1970

III.B.2.N.D.20. SYMPHORICARPOS OCCIDENTALIS TEMPORARILY FLOODED
SHRUBLAND ALLIANCE

SYMPHORICARPOS OCCIDENTALIS SHRUBLAND

Western Snowbeny Shmbland

Element Concept
Suinmai'y: This western snowberiy shrubland is found in the western tallgrass and northern Great Plains of the
United States and Canada. Stands occur in mesic depressions and swales, typically surrounded by upland
grassland communities. Tlie soils are silts and loams. Tliis type lias three distinct vegetation layers, a shnib layer
(approximately 80 cm tall), a graminoid- dominated layer (approximately 30 cm tall), and a f orb-dominated layer
(<20 cm tall). S\-mphoricarpos occidentalis is the predominant species in the slinib layer and at times forms
almost monospecific stands. Rosa woodsti commonly occurs interspersed with the £>ymphoricarpos ocadentalis.
Other shrubs^ such as Rhus aromatica and Prunus virgtniana, often occur as thickets on the fiinge of this

AppendixE-lS

commiuiity. Rhus aroniatica and Prunus virginiana can reach 2 m or more. Tlie herbaceous layer is poorly
represented where the shnibs are dense, although Poa pratensis occurs in many stands. Common forbs inchide

Artemisia ludoviciana, Solidago spp., andAchillea millefolium. Vines, such as Parthenocissus vitacea, are often
found climbing through the shrubs. This type is frequently observed in heavily grazed meadows and prairies.

Envli^onment: This community is found in mesic swales, depressions, ravines andfloodplains. Some examples
of this community experience intermittent and brief flooding. Tlie soils are fertile and well-drained to imperfectly
drained silts and loams. Tlie upper soil horizon is usually deep, although a thin layer of sand may be present if the
site has been recently flooded (Jones and Walford 1995).

Vegetation: Tliroughout its range this community is dominated by shrubs approximately 1 m tall. Shrub cover is
typically greater than 50%, and in places it can approach 100%. Tliese shrubs form dense chimps tliat exclude
most other species. Symphoncarpos occidentahs is the most common shrub, but Rhus aromatica (or Rhi^
tnlobata) and Pi'iimis virginiana can be locally abundant and can grow to 2-3 m in places. Toxicodendron
rydbergii may also be present. Herbaceous species and smaller shrubs are most abundant at the edges of this
commimity and in gaps between the chimps of taller shrubs where the shading is less complete. Rosa woodsii is a
typical smaller shrub. Common graminoids include Pascopyrum smithn nnd Poa pratensis. Achillea millefolium,
Artemisia ludoviciana, Galium boreale, and Solidago spp. are common forbs of this community. Woody vines
sometimes occur, including Parthenoci:^sus vitacea.

Dynamics: Stands may occasionally be flooded (Jones and Walford 1995). Symphoncarpos occidentahs seems to
tlirive in disturbed areas (Hansen and Hoffman 19SS), especially those subject to disturbance by ftre and cattle
grazing.

GRank & Reasons: G4G5 (96-02-01). This type is common throughout tlie northern Great Plains. Historically,
it may never have been veiy extensive. It has been observed to grow out from forest or woodland edges and shade
owX the grasses. It is tolerant of both grazing and flre (Hansen and Hoffinan 198S), and is under no threat ftom
human activities. In some cases, heavily grazed pastures may favor tliis types. Many examples are somewhat
weedy; thus the type is not demonstrably secure.

Comments: Tliis type often occurs in heavily disturbed areas in conjunction with exotic species such as Poa
pratensis and Cirsnim an'ense. Because it occurs in mesic swales, depressions, ravine bottoms andfloodplains,
some stands are occasionally flooded whereas others are just veiy moist. Thus it tends to fall on both sides of the
upland/wetiand division.

Element Distribution
Range: Tliis western snowberry shrublandis found in the western tallgrass and northern Great Plains of the
United States and Canada.

States/Provinces: CO:S3, lA?, MB?, MT:S4S5,ND:S4?,NE:S4, SD:SU, SK:S?, WY:SR

Element Sources
Authors: Drake, J. F, WCS Confidencf : 3 Identifier: CEGL001131

References: Bourgeron andEngelking 1994, Cluisty 1973, Clark 1977b, Clark etal. 19S0, Driscoll et al. 1984,
Hansen and Hoffinan 19SS, Hansen et al. 1984, Hansen et al. 1991, Hansen et al. 1995, Johnston 1987, Jones
1992b, Jones and Walford 1995, Kittel etal. 1994, Kittel et al. 1999, McAdams et al. 199S, Meyer 19S5, Steinauer
and Rolfsmeier 2000

Appendix E -19

in.B.3.N.a. Extremely xeromorphic deciduous subdesert shrubland without
succulents

III.B.3.N.A.14. SARCOBATUS VERMICULATUS SHRUBLAND ALLIANCE

SARCOBATUS VERMICULATUS / Pseudoroegneria spicata Shrublakd
Black Gieasewood / Bluebunch Wlieatgiass Shnibland

Element Concept
Summai'y: This greasewood commiiiiity is foimd in the badlands regions of the northwestern Great Plains. Stands
are foimd on weakly consolidated sedimentaiy rocks, where eroded slopes contain iuterbedded clay and silt shales.
Slopes rauge from 0-S0%, aud average about 35 -40%, with a southwest- to soutli east-facing aspect. A tliin cmst of
highly saliue salt 1-5 cm in deptli may form on the surface. Soil pH is aroimd 8.0. Stands have a sparse to
moderate woody layer (1 5 -40% cover) dominated by tlie deciduous, facultative halophytic shrub Sarcobatus
vermiculatus. Other characteristic shrubs aud dwarf-shrubs may iiwAwde Artemisia tridentata,Atriplexcanescsns,
Encamena nauseosa {= Chiysothamnus nauseosiis), and Gutieirezia sarothrcie. The herbaceous layer ranges from
absent to moderately sparse cover (<25%) of scattered tall and medium -tall bunch grasses, such as
Pseudovoegnena spicata, Achnatherum hymenoides (= Oryzopsts hymsnoides), aud the sod grass Bouteloua
gracilis. Auuual grasses, especially the exotic Bromus tectorum and Bi'omfis japomcus, may be present. Forbs are
sparse, except on disturbed, weedy sites. Forb species may include Enogonum paiiciflorum, Srmeda
calceohformis, or Sphaeralcea coccmea. Occasioually, cacti, such as Opuntia fragilis or Opiintia polyacantha,
may also be preseut.

Envli^onment: Stands occur in the badlands regious of the uorthwesteru Great Plains, where they are found ou
weakly consoh dated sedimentaiy rocks. Tlie badland topography is composed of outcrops of parallel beds of clay
aud silt shales, interspersed in some regions witli liguite (coal) seams of varying thickness, massive outcroppiugs of
sandstoue stiata, and colluvial talus of clay, silt and fragments of sandstone (Brown 1971). This commiiuity is
found on the iuterbedded clay and silt shales. Slopes range from to 80%, and average about 35-40%, with a
southwest- to south east- facing aspect. On steeper slopes, this community is found on residual iuterbedded clays
aud silts, witli occasioual bands of lignite that are from several centimeters to over a meter in thickness, and stands
are usually 0.5 ha iu size. On more gentle slopes, they are found ou alluvial materials of stream terraces and may
range iu size up to 4 ha or more. A thin crust of highly saline salt 1 to 5 cm in depth may form on the siuface.
Tliese crusts form iu places where substantial movement of subsurface water accumulates higli concentrations of
salts and sodium near tlie surface through high evaporation rates (Browu 1971). Tlie porous lignite seams may
cause subsurface water to move horizontally to the surface on the hillsides (Hanseu and Hoffman 19SS). The upper
audlower soil horizons contain conceutrations of sodium salt of 9.1 to 12.00 me/100 g (Brown 1971). Soil pH is
around S.O.

Vegetatiou: Stands have a sparse to moderate woody layer (1 5 -40% cover) dominated by the deciduous,
facultative halophytic shrub Sarcobatiis vermiculatus. Otlier characteristic shrubs and dwarf-shrubs may iuclude

Artemisia tndentata, Atnplex canescens, Encameria nauseosa (= Chrysothamnns nauseosns)^ and Gidierrezia
sarothrae. The herbaceous layer ranges from absent to moderately sparse cover (<25%) of scattered tall and
medium-tall buuch glasses, such as Pseiidovoegnena spicata, Achnathenini hymenoides (= Oryzopsis
hymenoides), and tlie sod grass Bouteloua graahs. Annual grasses, especially the exotic Bromus tectorum and
Bromus japonicus may be present. Forbs are sparse, except on disturbed, weedy sites. Forb species may include
Eriogonum pauciflorum, Suaeda calceoltformis, or Sphaeralcea coccmea. Occasionally, cacti, such as Opuntia
fragilis or Opuntia polyacantha, may also be present (Browu 1971, Hansen andHoffiuan 19S8).

Dyuamics: Natural disturbances include ongoing erosion of badlands topography, and, where stands are near
stieams, occasional frash Hoods.

GRank & Reasous: G3 (99-09-23). Tliis type is restricted to Badlauds topography in the uorthem Great Plains,
rarely exceeding 4 -5 ha iu size. Sites are not particularly threatened, but site requirements are veiy specialized
(liighly salty subsurface soils) and localized.

Appendix E-20

Element Distribution
Range: Tliis community is fomid in the badlands regions of southeastern Montana and western South Dakota, and
possibly in northeastern Wyoming and western North Dakota.

States/Provinces: MT:S3,ND:S?, SD:S?, WY?

Element Sources
Authors: D. Faber-Langendoen, WCS Confidence: 1 fdentifier: CEGLOOf 367

References: Bourgeron andEngelking 1994, Brown 1971, Driscoll et al. 19S4, Hansen 19S5, Hansen and
Hoffinanl988

Appendix E -21

V. HERBACEOUS VEGETATION

VA.S.N.a. Tall sod temperate grassland

V.A.5.N.A.3. ANDROPOGON HALLII HERBACEOUS ALLIANCE

Andropogon HALLII - Calamovilfa longifolia Herbaceous Vegetation
Sand Blue^tem - Prairie Sandreed Herbaceous Vegetation

Element Concept
Suinmai'y: Tliis sand prairie community is found in the uorthem and central Great Plains of the United Slates and
Canada. Stands are found on sandy deposits, usually on gentle to moderate slopes, ranging from stabihzed rolhng
to choppy saud dunes. Tlie soil is saud, loamy sand, or sandy loam, often erodible, and somewhat poorly
developed. Tliis community is dominated by moderately widely spaced mid to tall grasses. The most abundant
species are Andiopogon hallii and Calamovilfa longifolia. Other graminoids that may be found in this commimity
include Bouteloua gracilis, Bouteloua hirsuta, Carex duriuscida, Carexfihfolia, Cavex mops ssp. heliophila,
Cyperus schweinitzii, Eragrosti^ trichodes, Hesperostipa comata (= Sttpa comata), Koelevia macrantha,
Muhlenbergia pungens , Redfisldia flexuosa , ^nd Schizachynum scoparium. Forbs and slirubs are a minor
component of the total vegetation. Characteristic forbs include Chenopodium subglabrum, Chamaesyce
serpyllifolia, Hehanthns pauciflovus, Hehanthiis petiolans, Lappula occidentalis vav. occidentalis, Liatris
punctata, Lithospermum incisum, Lygodesmia jimcea, Monarda punctata, Oenothera rhombipetala. Penstemon
haydenii (in Nebraska), nnd Pso rah dmm lanceolatiim. Artemisia frigida and Yucca glauca are the most common
slirubs, especially on wiud-blown dime crests and choppy slopes in Nebraska sandliills. Li soutlieastern North
Dakota, a subtype containing tallgrass species may be distinct; species include AwtAi-opogon gerardu,
Syniphyotnchum encoides [= Aster ericoides), Lithospermum canescens, Sohdago nemoralis, and ^orobolus
heterolepis.

In Montana, this plant association is uncommon as a widely-scattered featme associated with active wind erosion.
Montana in general does not have the choppy dime systems that characterize the Nebraska Sandhills and the glacial
lake sandliills elsewhere in the northern Great Plains, where they are more extensive and well-developed. Tliis
plant association is at the ''rim" of blowouts within the most similar of Montana landscapes, i.e., the Medicine
Lake sandliills of Sheridan County. But, tliis type is so small and narrow a vegetation band that it was not included
in the description of plant associations here. Tliere is more habitat for it in the imglaciated sedimentary plains of
tlie Fort Union Fonnation at localized erosion features associated with sandstone outcrops, though widely- scattered
and in small pockets. In Powder River County, this plant association is uncommon in places with sandstone
outcrops as found in at least the eastern end of the County.

Envli^onment: This community is usually found on sandy deposits, such as dunes, with gentle to moderate slopes
(Johnston 19S7). Tlie soil is sand, loamy sand, or sandy loam and often erodible. Hirsch (1985) reported that
stands of this type in southwestern North Dakota were small, generally less than 0.05 ha.

In Montana and Powder River County, this plant association is restricted to active wind erosion features in the
Sands ecological sites, most often in the sideslopes of a blowout but also at tlie rim. It occurs in Powder River
County within tlie 10-14 in ppt. zone, and at higher precipitation levels elsewhere.

Vegetation: This community is dominated by moderately widely spaced mid to tall grasses. The most abundant
species are An^'opogon hallii and Calamovilfa longifolia. Other graminoids that may be found in this community
include Bouteloua gracilis, Bouteloua hirsuta, Carex duriuscula (= Carex eleochans), Carexfihfolia, Carex mops
ssp. heltophila, Cyperus schweinitzii, Eragrostis trichodes, Hesperostipa comata (= Stipa comata), Koelevia
macrantha, Muhlenbevgia pungens. Redfteldia flexuosa^ awd Schizachyrtun\ scopariun\. Forbs and shrubs are a
minor component of the total vegetation. Characteristic forbs include Chenopodium subglabrum, Chamaesyce
serpyllifolia (= Euphorbia serpyllifolia), Hehanthus pauciflorus, Helianthus petiolans , Lappula occidentalisvar.
occidentalis, Liatris punctata, Lithospermum inasum, Lygodesmia junce a, Monarda punctata, Oenothera
rhonibipetala, Penstemon haydenii (in Nebraska), and Psoralidiuni lanceolatum. Artemisia fngida and Yucca
glauca are the most common shnibs, especially on wind-blown dime crests and choppy slopes in Nebraska

Appendix E -2 2

sandliills (Steinauer anclRolfsmeier 2000). On eroding parts of the Nebraska Saudliills a number of different
species may occur, including Chamaesyce geyen, Chamaesyce missunca, Chenopodmm beii^wdien.

Chenopodium pratencola, Cycloloma atripltcifolmm , Engeron bellidiastrum , Enogonum anmmm, Froelichia
floridana var. campestns, Ipomop^ts longiflora, and Linum I'lgidiini. Redfieldia flexuosa is common iu blowouts
(Steiuauer and Rolfsmeier 2000). In southeastern North Dakota, a subtype containing tallgrass species may be
distinct; species include A\\6^opogon gerardu. SiTiiphyotnchura encoides (= Aster encoides), Lithospevmum
canescens, Solidago nemoralis, and Sporobolus heterolepis (Burgess 1965). In soutliwestem Kansas, Calaniovilfa
gigantea may be present (Lauver et al. 1999).

In Montana, the vegetation is dominated or co-dominated by And^opogon hallii and Calamovdfa longifolta.
Sometimes they sort in separate small bands by microliabitat and succession^ but they are more often intermixed.
Other graminoides that are often present incXwd^ Achnatherum hymenoides, Sporobolus ciypt?i\i^'iis and

Hesperostipa comata. Forbs ty'picTAXy incXwd^ Ambrosia pstlostachy a, Enogonum annuum, Helianthus pettolaris ,
Lygodesmia juncea, Psoraltdium lanceolatum, and Tvadescantia occidentalis.

Dynamics: Blowouts may occur in this community type, leading to bare soils or subsoils. Blowouts may be
related to severe diouglits and windstorms, and may occur in conjunction with grazing pressures or fires that
reduce the ability of the vegetation cover to stabihze tlie sand. An^-opogon hallu - Carex mops ssp. hehophila
Herbaceous Vegetation (CEGL001466) may be an early successional phase on blowouts, at least in the northern
states (Burgess 1965). Blowouts may subsequently develop into tliis type where sands have been stabilized and
vegetation cover and diversity are high.

GRank & Reasons: G4G5 (00-03-24). This type has a relatively restricted distribution in teiins of site
characteristics, but has a wide distiibution in the northern Great Plains. Tlie community is reported fi'om 7
ecoregional sections in Kansas, Nebraska, Montana, South Dakota, North Dakota, Manitoba, and Saskatchewan.
Stands are typically less than a few hectares in size in tlie nortliern parts of the range, but can be quite extensive in
tlie Nebraska Sandhills. Total coverage is over 100,000 acres. Tlneats are not known.

Higli-ranked species: This plant association or closely related ones harbor many SI and S2 plant species in
Montana, including Chenopodmm subglabnim, Ciyptantha fendlen, Cyperus schweimtzn, Dalea villosa var
villosa. Mentzeha nuda. Psoralea lanceolata, and possibly others.

Comments: Stands in this association may vary from north to south and east to west. More northern stands may
have higher dominance by Carsx fill folia or Carex mops ssp. heliophila. Distinctions between this type and
Andi-opogon hallii - Carex mops ssp. heliophila Herbaceous Vegetation (CEGL001466) are not entirely clear.
Note tliat Looman (19S0) describes this type for Manitoba, but these northern stands also contain Carex siccata (=
Carex foenea), Danthonia spicata, and Festiica ovma. Cuiiently tlie North Dakota Heritage Program restricts this
type primarily to the tallgrass prairie region of the state, where sands are deep, as described in part by Burgess
(1965): however, it is reported farther west in soutliwestern North Dakota (Hirsch 1985) and Montana. Rangewide
application of this type needs further review. In Minnesota, relatively small Calamovilfa /o^^i/o^j^- dominated
patches can occur in dry sandpraiiies or barrens, particularly on crests of dunes, but these are treated as part of
Schizachynum scopariuni - Hesperostipa spartea - Bouteloua {curtipendiila, gracilis) Sand Herbaceous Vegetation
(CEGL005204). Andiopogon hallii does not occur as a native species in Minnesota. Steve Kettler (pers. comm.
199S) indicated that this association does not occur in Colorado (although tliey once tracked it). All of their
sandliill types Qoni^inArtenusiafilifolia and are classified {or will be reclassified) ^sAftemisia filifolia /
Andi'opogon hallu Shrubland (CEGL001459). NRCS range site descriptions state that abimdance of Artemisia
filifolia should be low, but Kettler thinks it is always present, otlierwise the vegetation and environment are similar.
He suggested that the presence or absence qI Artemisia filifolia seems to make a good split between the southern
(Colorado and south and east) and tlie northern (Nebraska and north) sandhills.

Element Distribution
Range: Tliis sand prairie community is found in the northern and central Great Plains of the United States and
Canada, ranging fiom Manitoba and Saskatchewan, south to Kansas.

In Montana, it is localized within the aeohan sand deposits of the Medicine Lake Sandhills. There exists
appropropii ate habitat in the unglaciated sedimentaiy plains at locahzed erosion features associated with sandstone

Appendix E -2 3

outcrops, tliough widely- scattered and in small pockets.

States/Provinces: KS:S2S3, MB:S?,MT:S?,ND:S?,NE:S5, SD:S?, SK:S?

Element Sources
Authors: Drake, J. F., WCS; mod. B. L. Heidel, MTNHP Coiifidfnce: 1 Identifier: CEGL001467
Referfiices: Bourgeron andEngelking 1994, Bmner 1931, Burgess 1965, Driscoll et al. 1984, Hirscli 1985,
Hoagland 199Sa, Johnston 1987, Lauver et a!. 1999, Loomau 1980, Ramaley 1939b, Soil Conservation Sei-vice
1978, Steinauer 1989, Steiuauer and Rolfsmeier 2000, Tolstead 1941, Tolstead 1942

ANDROPOGON HALLII - CAREX INOPS S3R HELIOPHILA HERBACEOUS VEGETATION

Sand Bluestem - Sun Sedge Herbaceous Vegetation

Element Concept
Suinmai'y: This sand blue stem prairie community type is found iu restricted areas of the northern Great Plains of
tlie United States. Stands occur on gently to steeply sloping terrain with saud or sandy loam soil. In Montana,
stands occiu' on slopes of any aspect, but north is the least likely. Li North Dakota, they occur on steep, choppy
sands. Tlie vegetation is veiy open, ranging fiom 15-50% cover. The taller herbaceous stratum of tliis community
is dominated by And; 0/3 0^0 ?i hallu^ witli associates of Calamovdfa longifoha, He^perostipa comata (= Sttpa
coniata}^ »nd Spoi'obolus ayptnndi'us. In southeastern North Dakota Koeleria macrantha, Redfisldia flexuosa^ and
Hesperostipa spartea (= Stipa spavtea) are present at low abundance. The lower herbaceous stratum is dominated
by Carex spp., especially Caj'ex mops ssp. helwphila. Other species that may be present Mt Artemisia fngida,
Carex fill folia, Carex dunuscula , Dalea villosa, and Yucca glnnca. Key diagnostic characteristics include the
choppy sand dune habitat, the very open structure of the vegetation, dominance by Andropogon hallii with Carex
inops ssp. heliophila and the presence of early successional species, such ^% Redfteldta flexiiosa.

Envli^onment: Tliis type is found on gentle to steep sloping terrain with sand or sandy loam soil. In Montana, it
can occur on slopes of any aspect but north is the least likely (MTNHP 1988). In North Dakota, it occurs on steep,
choppy sands (Heidel 1984a).

Vegetation: The vegetation is veiy open, ranging from 15-50% cover (Burgess 1965). The taller herbaceous
stiatum of this community is dominated by An djqpo^o?? hallu y\^ith associates of Calamovilfa loiigifolia.

Hesperostipa cor\iata (= Sttpa comata}, and ^oroboliis cryptnndius. In southeastern North Dakota Koelena
macrantha, Redfieldia flexuosa, ^nd Hesperostipa spartea (= Stipa spartea) are present at low abundance, and
Carex tnops ssp. heliophila is not present (Burgess 1965, Nelson et al. 19S1). The lower herbaceous stratiun is
dominated by Carex spp., especially Carex mops ssp. heliophila. Other species that may be present avG Artemisia

frigida, Carex filifolia, Carex durmscula (= Carex eleochans), Dalea villosa (= Petalostemon villosus)^ and Yucca
glauca.

Dynamics: Blowouts may occur in this commiuiity type, leading to bare soils or subsoils. Blowouts may be
caused by severe dioughts and windstorms, and may occur in conjunction with grazing pressures that reduce tlie
ability of the vegetation cover to stabilize the sand Tliis type may be an early successional stage on these
blowouts where vegetation cover and diversity are low. It may develop into Calamovdfa longifolia - Andropogon
hallii Herbaceous Vegetation (CEGL001469) (Burgess 1965).

GRank & Reasons: G3 (96-02-01). Tliis type has a veiy restricted distiibution both geographically, and in teiins
of site characteristics. Stands are only known from soutlieastern Montana and soutlieastern North Dakota, where
tliey are typically less than a hectare in size. A recent rapid ecological assessment of the Northern Great Plains did
not turn up any sites for this type, substantiating its restricted nature (Martin et al. 1998). Tlireats are not known.

Comments: Tliis association occurs only in limited places. Rangewide review is still needed, e.g., distinctions
between it and Awdiopogon hallii - Calamovdfa longifolia Herbaceous Vegetation (CEGL001467) are not entirely
clear. Awd^-opogon hallii occurs in Manitoba, but stands are placed in t\\t And)-opogon hallii - Ccdaraovilfa
longifolia Herbaceous Vegetatiou (CEGL00I467) [see Looman 1980]. Stands in southeastern North Dakota may
contain more tallgr ass prairie associates^ such as Awdiopogon gerardii, Symphyotnchum ericoides {= Aster

Appendix E-24

sj'icoide^), Lithospermum canescen^, Solidago nemotahs, and Sporobolus heterolspi:^^ than those in Montana.

The name of this association should probably be changed to Calamovilfa longifolia - Carex mops ssp. helwphila -
Carex fill folia Herbaceous Vegetation. Carex filifolta occurs on a wider variety of substiates than does Cavex
inops ssp. hehophila, which is more restricted to lighter sands. Steve Cooper (pers. comm. 1998) also notes that
Car sx fill folia occius farther nortli and west in Montana than does Carex mops ssp. hehophila. In Montana, Carex
inops ssp. hehophila also occms on shales that have been weathered to sand particles. In North Dakota, this type is
restricted to the western part of the state.

Element Distribution
Range: Tliis sandbluestem prairie community type is found in restricted areas of the northern Great Plains of the
United States, including southeastern Montana and southeastern North Dakota.

States/Provlnces: MT:S3,ND:S?

Element Sources
Authors: J. Drake, WCS Confidence:! Identifier: CEGL001466

References: Bourgeron andEngelking 1994, Burgess 1965, Culwell and Scow 1982, DriscoU et al. 19S4, Heidel
1984a, Looman 19S0, MTNHP 1988, Nelson et al. 19S1

V.A.5.N.A.11. CALAMOVILFA LONGIFOLIA HERBACEOUS ALLIANCE

Calamovilfa longifolia - Carex INOPS ssp. helwphila Herbaceous Vegetation
Praiiie Sandreed - Snn Sedge Herbaceous Vegetation

Element Concept
Summai'y: This prairie sandreed grassland is found in tlie northwestern Great Plains of the United States and
Canada. Stands typically occur on gentle slopes bnt can also be found on flat land or moderate to steep slopes.
Soils are thin sands, sandy loams, and loamy sands, in places derived from sandstone. Moisture levels may be high
deeper in the soil profile. Most stands of this community are not veiy large. Tlie vegetation is dominated by
graminoids, with two strata, one of mid to tall grasses, the other of dense short sedges. Shrubs are uncommon. In
the taller grass layer, the most abundant species is Calamovilfa longifolia. Other species found in this layer include
Koelena macrantha, Schizachyrmra scopnnum, ^nd Hesperostipa coraata (= Stipa coraata). Pascopyrum smithti
may be present on some stands with finer soil textures. The short graminoid layer is composed chiefly of Carex
filifolta and Carex mops ssp. hehophila, which may have high cover vahies. Other upland Carices, such as Carex
diiriusciila, as well as Bouteloiia gracilis midMuhlenbergia pnngens, may also be present. Forb species diversity
is moderate but they do not contribute greatly to the cover. Tlie forbs that are typical of this community include
Artemisia dvacunculus, Artemisia frigida, Artemisia ludoviciana, Chenopodium album, Chenopodium
leptophyllum, Lathyrus spp., Liatris punctata, Lygodesmia jiincea. Phlox hoodii, and Psoraliditun lanceolatum.

Envii^onment: Stands are found on gently rolling uplands witli little to moderate slopes (typically between and
20%, bnt occasionally as high as 39%) (Hirsch 1985, Hansen and Hoffman 1988). Tlie soils are sand, sandy loam,
or loamy sand and there is rarely substanfial soil horizon development (Hanson and Whitman 193S). TTie parent
material is sandstone (USES 1992). Moisture levels may be high deep in the profile.

In Powder River County, tliis plant associafionis found within the Sandy Ecological Sites of the 10-14 and 15-19
inch precipitation zones.

Vegetation: Tlie vegetafion structure is somewhat open, with cover averaging 65% in parts of its range (USFS
1992). The vegetation is dominated by graminoids, with two strata^ one of mid to tall grasses, the otlier of dense
short sedges. In the taller glass layer, the most abundant species is Calamovilfa longifolia. Other species foimdin

this layer inchide FCoeleria macrantha, Schizachyriunj scopanum, and Hesperostipa comata (= Stipa comata).
Pascopyrum sniithii may be present on some stands with finer soil textures. The short- graminoid layer is
composed chiefly of Carex filifolia and Carex inops ssp. hehophila, which may have high cover values. Other
upland Carices, such as Carex duruiscula (= Cavex eleocharis), as well as Bontelona gracilis mid Muhlenbergia

Appendix E -2 5

pungens, may also be present. Forb species diversity is moderate, but they do not contribute greatly to the cover
(Hausou audWIiitman 193S, USFS 1992). Tlie forbs that are typical of this community include Artemisia
dvacuncuhis, Artemista fngidci (considered a shnib by some ^wthoxi^, Artemisia liidoviciana, Chsnopodium album,
Chenopodium leptophyllum, Lathynis spp., Li atris punctata, Lygodssmia juncea. Phlox hoodn, and Psoralidium
lancsolatum. Shnibs are uncommon. Wlien shrubs are present they are short shrubs such as Yucca glauca, Rosa
spp., ?iudArtemisia fngida (considered a forb by some authors).

GRank & Reasons: G3 (96-02-01). No occurrences have been documented, but the community is reported in 3
ecoregional subsections in Wyoming, Montana, North Dakota, Sonth Dakota, and Saskatchewan. It is a very
uncommon community in Badlands National Park, South Dakota.

Comments: The name of this association should probably be changed to Calamovilfa longifolia - Carex mops ssp.
heliophila - Carex fthfolia Herbaceous Vegetation. Cavex fiUfoha occurs on a wider variety of substrates tlian does
Carsx inops ssp. hsliophila, which is more restricted to lighter sands. Steve Cooper (pers. comm. 1998) also notes
that Carex filifolta occurs fartlier north and west in Montana than does Carsx inops ssp. heliophila. In Montana,
Carex inops ssp. heliophila also occurs on shales that have been weathered to sand particles. Li North Dakota, this
type is restricted to the western part of the state.

Element Distribution
Range: This prairie sandreed grassland is found in the northwestern Gieat Plains of the United States and Canada,
ranging from the western Dakotas to Montana and Saskatchewan.

States/Provinces: MT:S3?,ND:SU, SD:S?, SK:S?

Element Sources
Authors: K. Hirsch, mod. J. Drake andD. Faber-Langendoen, WCS; mod. B. L. Heidel, MTNHP Confidence: 2
Identifier: CEGL001471

Referfnces: Bourgeron andEngelking 1994, DriscoU et al. 1984, Hansen 19S5, Hansen and Hoffinan 1988,
Hansen etal. 1984, Hanson and Wliitman 1938, Hirsch 1985, USFS 1992

Calamovilfa longifolia - Hesperostipa comata Herbaceous Vegetation
Prairie Sandreed - Needle- and- Tine ad Herbaceous Vegetation

Element Concept
Suinmai'y: This prairie sandreed grassland community type occurs in the central and northern Great Plains region
of the United States. Stands occur on stabihzed sand dunes, as well as in interdunal vaUeys, coUuvial sands, and,
less commonly, silty terraces of intermittent streams. Soils are mediimi to fine sands foiined either fiom eolian or
colluvial processes. Tlie vegetation has an open canopy, dominated by mid to tall grasses. Calamovilfa longifolia
and Hespevostipa comata (= Stipa comata) are the most conspicuous and dominant grasses. Other common
grasses include Bouteloua gracilis, Koeleria macrantha, Achnatheruni hymenoides (= Oryzopsis hymenoides),
^orobolus ciypt?[n6i'HS . The type may grade into stands dominated by Pascopyrum smithit and Nassella viridula
(= Stipa vindula) at tlie base of slojjes. Andi'opogon hallii or Hesperostipa spartea (= Stipa spartea) may also be
present. Sedges are rare, but could include Carex inops ssp. heliophila. Forb diversity ranges from low to
moderate, depending on the site. Diy valley sand prairies may be particularly forb-rich. Silty terraces of
inteiinittent streams may cout^iu Artemisia frigida, Artemisia ludoviciana, Gutierrezia sarothrae, Psoralidium
teniuflorura, and Yucca glauca. Shrubs are scattered and infrequent to absent, with Rhus trilobata the most
common species. Tliese areas are higlily susceptible to invasion by exotic brome grasses (Bromus japonicus,
Bromiis squarrosus, Bromus tectorum) and may be quite weedy.

Envii^onment: Stands occur on stabilized sand dunes, as well as in interdimal valleys or diaws, colluvial sands,
and, less commonly, silty terraces of intermittent stieams. Soils are medium to fme sands formed either from
eolian or colhivial processes. For example, in Nebraska stands occur below sandstone ontcrops and escarpments.
More rarely, stands occnr on floodplain teiraces of intermittent streams, where soils are moderately deep, poorly
drained, silty loams and loams (Heerwagen 1958, USDI 1979, Barnes et al. 19S4, Steinauer andRolfsmeier 2000).

Appendix E -2 <5

In Powder River County, this plant association is foimdin the Sandy Ecological Sites of the 10-14 inch
precipitation zone.

Vegetation: The vegetation has an open canopy, dominated by mid to tall grasses. Calaniovilfa longifolta is the
most conspiciions grass. Other common grasses include Bouteloua gracilis, Bonteloua gracilis, Koelei'ia
maci'antha, Achnatherum hymenoides (= Oiyzopsis hynienoides), Spofobolu:^ ciypt?in6ii'us^ and Hesperostipa
coniata (= Stipa comatct). Pciscopyrum smithn (= Agropyron sraitha) v^ndNassella vindnla (= Stipa viridula) may
occur on more level sites at the base of slopes (Barnes et al. 19S4, Steinauer and Rolf smeier 2000). An^-opogon
hallii may also be present. Sedges are rare but could include Cavex mops ssp. hehophila. Forb diversity ranges
fi'om low to moderate, depending on the site. Diy valley sand prai lies may be particularly forb-iich. Silty terraces
of intermittent streams may contain Aiteniisi a fngida, Artemisia ludoviaana, Gutierrezia sarothrae, Psorahdium
tenuiflonini, and Yucca glauca (Steinauer and Rolf smeier 2000). Shrubs are scattered and infiequent to absent,
with Rhus trilobata the most common species. These areas are higlily susceptible to invasion by exotic brome
grasses {Bromus japomcus , Bromus squan'osus, Bromus tectorum) and may be quite weedy (Heerwagen 1958,
USDI 1979, Steinauer and Rolfsmeier 2000).

Dynamics: Blowouts caused by diought and wind may occur in this type. Tlie type probably represents a later
successional stage. Earlier stages may be dominated by An<\>opogon hallu {e.g., An6^-opogon hallu - Calamovilfa
longifolia Herbaceous Vegetation (CEGL001467)). Heavy grazing may increase the hkelihood of blowouts.

GRank & Reasons: G3 (96-02-01). Tlie community is reported in 2 ecoregional sections in Wyoming, Colorado,
and Nebraska. It is restricted primarily to stabihzed sand dimes, as well as ininterdunal valleys or diaws, colluvial
sands, and intermittent streams, but it has a moderately wide distribution in the cental to northern Great Plains.
Stands are typically less than a few hectares in size, but larger stands are found in interdimal valleys in Nebraska,
some reaching 100 acres or more {G. Steinauer pers. comm. 1999). Li Nebraska, this community can be heavily
grazed and subsequently invaded by exotic species (Steinauer and Rolfsmeier 2000).

Comments: Tliis type may perhaps be differentiated from otlier types, such as Calamovilfa longifolia - Carex
inops ssp. hehophila Herbaceous Vegetation (CEGL001471), by the absence or low abimdance of Carcx filifolia
and Cavex inop^ ssp. hehophila^ though why those species are not abundant in this type is not clear. Further
floristic comparisons need to be made to help make tlie distinction clear between that type and this type. Some
floristic variability is to be expected in this type, based on successional patterns following dime blowouts. Steve
Kettler {pers. comm. 199S) says they don't have this type in Colorado. It sounds like a version of a locally
described Ands-opogon hallu - Hesperostipa comata type, of which Colorado is also not very confident. Kettler
suspects that a lot of the variation in glass dominance is fiom different management (grazing) over the years. The
silty terrace stands are reported from tlie White River drainage in northwestern Nebraska and Badlands National
Park, South Dakota (VonLoh et al. 1999, Steinauer and Rolfsmeier 2000).

Element Distribution
Range: Tliis prairie sandreed grassland community type occurs in the central and northern Great Plains region of
tlie United States, ranging from Colorado and Nebraska, nortli to Wyoming and South Dakota.

Tliis type has been documented in Powder River County, Montana.

States/Provinces: AB?, CO?, MT:S3, NE:S?, SD:S?, WY:S3

Element Sources
Authors: G. Steinauer and S. Rolfsmeier, mod. D. Faber-Langendoen, WCS; mod. B. L. Heidel, MTNHP
Confidencf: 2 Identlfifr: CEGL001473

Referfuces: BLM 1979b, Barnes et al. 1984, Bourgeron andEngelking 1994, CDM Consultants n.d., Driscoll et
al. 19S4, Heerwagen 1958, Johnston 1987^ Mine Reclamation Consultants 1977, Steinauer and Rolfsmeier 2000,
YonLohet al. 1999

Appendix E -2 7

V,A.5.N,c, Medium -tall sod temperate or subpolar grassland

V.A.5.N.C.29. HESPEROSTIPA COMATA - BOUTELOUA GRACILIS HERBACEOUS
ALLIANCE

HESPEROSTIPA COMATA - BOUTELOUA GRACILIS- C AREX FILIFOLIAHEKB ACEOUS VEGETATION

Needle-and-Thread - Blue Grama - Threadleaf Sedge Herbaceous Vegetation

Element Concept
Summai'y: This ueedlegrass - grama grass prairie community is common iu tlie northern and ceuhal Great Plains
of the United States. Stands occur on flat to r oh iug topography with deep (40-100 cm), sandy loam to loam,
coarser-textured soils. Tliey are typically associated with uplands, though they may also occur lower in the
landscape, such as coulee and draw bottoms, if soils are sufficiently coarse (usually sandstone-derived). Tlie type
is foimd at elevations ranging from 600-1700 m (2000-5500 feet); average annual precipitation associated with
fliese elevation param ranges from shghtiy less than 25 cm to over 50 cm {10-20 inches). The vegetation is
dominated by moderate to moderately dense medium-tall grasses. Hesperostipa comata {= Stipa comata) is the
tallest of the dominant species, sending seed heads to a maximum height of approximately 1 m. Tlie rhizomatous
graminoids Bouteloua gracilis and Carex filifoha ^ tlie other two doni in a nt/co dominant species, do not usually
exceed 0.5 m. Calamovilfa longifoha is often foimd with high cover values on sandier soils, and Koelena
macrantha cover increases on degraded sites. Tliere are regionalized expressions of variability with Carex inops
ssp. heliophila surpassing Carex fdi folia in Colorado and Calamagrostts montanensis being at least as important as
the diagnostic species in noith-central Montana. Pascopyrum smithit is consistently present. For woody species,
siibshrub forms (Artemisia fiigida, Gutierrezia sarothrae, Rosa arkansana) have the highest cover and constancy,
but their total cover does not sum to more than 5%, except on overgrazed sites. Cover values for forbs are low (the
exception being Selagmella densa). Geographic setting influences forb composition to some degree, with
^haeralcea cocanea. Phlox hoodit, Hetevotheca villoma, Gaura cocanea^ and Liatns punctata common in the
noithem areas, ^nd Lygodesmia juncea, Opuntia polyacantha, Avtenusia dracunculiis, aud Ratibida colummfera
seeming to increase to the eastern and southern areas.

Envii'onment: Stands occur on flat to rolling topography with deep (40-100 cm) sandy loam to loam soils. Tliey
are typically associated with uplands, though they may also occur lower in the landscape, such as coulee and draw
bottoms, if soils are sufficiently coarse (usually sandstone derived). Even though it is a major association in the
Northern Plains, it does not occur in areas dominated exclusively by shale and mudstone parent materials, from
which heavy soils are derived. This type is found at elevations ranging from 600 to 1700 m (2000-5500 feet);
average annual precipitation associated with these elevation parameters ranges fiom slightly less than 25 cm to
over 50 cm (10 to 20 inches).

Vegetation: Tlie vegetation is dominated by moderately dense graminoids that are usually between 0.5 and 1 m
tall. For example, on 19 stands in west-cenhal Montana the cover by tiie different strata was as foUows: shrubs
6%, graminoids 67%, forbs 11%, biyophytes 14%, titter 55%, rock 4%, bare soil 9% (Miieggler and Stewart 1978).
Thilenius et al. (1995) found that the average cover on 14 stands in eastern Wyoming was 42%. Hesperostipa
comata (= Stipa comata) is the taUest of the dominant species, sending seed heads to a maximum height of
approximately 1 m. The rhizomatous graminoids Bouteloua gracilis and Carex filifolia , the other two dominant/
codominant species, do not usually exceed 0.5 m. Calamovilfa longifolia is often found with liigh cover values on
sandier soils and Koelsria macrantha cover increases on degraded sites. There are regionalized expressions of
variability with Carex mops ssp. heliophila surpassing Carex fi I foil a in Colorado and Calaniagrostis montanensis
being at least as important as the diagnostic species in north-cenhal Montana. Pascopyrum snuthii is consistentiy
present. For woody species, subshrub forms {Arteraisia frigida, Gutierrezia sarothrae, Rosa arkansana) have the
highest cover and constancy but their total cover does exceed more than 5%, except on overgrazed sites. Cover
values for forbs are low throughout the range of tlie type (the exception being Selaginella densa). Geographic
setting does influence forb composition to some degree. Sphaeralcea coccinea, Phlox hoodii, Heterotheca villosa,
Gaura coccinea^ ^nd Liatr is punctata, have high constancy values in northern areas, whereas in the eastern and
southern portions of the range Lygodesmia juncea, Opuntia polyacantha, Artemisia dracunculus and Ratibida
columnfera seems to be more constant.

AppendixE-2S

Dynamics: Vast (singly and in tlie aggregate) prairie dog (Cynomys ludovicianus) "towns" once developed on the
favorable substrates of tliis type and exploited its vegetation. Prairie dog populations have undergone a precipitous
decline since settlement, so much of this type conld be in various states of secondary succession, returning from a
somewhat denuded slate and altered composition created by tlie prairie dogs (and attendant bison that found
nutritions forage here). Fire, both aboriginal- and lightening- caused, was a regular part of this landscape. Fire-
retum intervals have been considerably lengthened since settlement by European- Americans. This association and
Pascopyrum sraithu - Bouteloiia gracilis - Carex filifoha Herbaceous Vegetation (CEGL001579) could be
considered the most common plant associations in the Northern Great Plains (Martin et al. 1998). These two
associations, cited by many authors as the chmatic climax communities for this region, are manifested by matrix or
large patch occuiiences frequently found dominating whole landscapes. The Hesperosttpa coraata {= Stipa
coniata) defined community is more associated with uplands and the Pascopyrum smithii defined type
characterizes sites with higher moisture status, generally occurring at lower positions in the landscape.

GRank & Reasons: G5 (99-02-25). Tliis is an exceedingly common type, manifesting any number of
permutations, some of which are related to disturbance and some of which appear to be related to the expected
geographic distinctions in such a broadly distributed type. Tlie only reason to consider it a G4 is that it has
received, and continues to receive, significant grazing pressure which, combined with the surge in alien weed
populations, pose a significant threat to its quality.

Comments: Carex ftlifoha is lacking or highly reduced in importance southward. Soutliern stands were once
classified separately (CEGL001699), and fiirther review of their characteristics compared to more northern stands
is needed. Weaver and Albeitson (1956) also remark on the fact that low sedges are present as far south as Texas
but are important only north of Colorado. However^ a phase of the Hesperostipa comata - Bouteloua gracilis type
of Mueggler and Stewart (1980) in western Montana is apparently quite similar to communities of the southern and
southeastern portions or the Northern Great Plains, andbotli lack Carex fth folia. Tliere are a welter of named
commimity types, mostly serai representations of grazing or fire impacts, that vary by having one or another of the
defining species (or even other graminoids, e.g., Carex mops ssp. heliophila) dominant. Tliis assemblage of types
is also defined by having relatively low cover of both Pascopyrum snuthti ^\nX Elymus lanceolatns (= Agropyron
dasystachyum). To accommodate these permutations within the concept of the type {as lesser-ranked occurrences)
or to recognize tliem as independent vegetation types recognized by existing vegetation composition is one
question. Another is, what cover value or degree of dominance of Pascopyrum snuthti or Elymus lanceolatns will
serve to establish the distinction between Pascopyi'um smithn - Hesperostipa comata - Carex filifolia (and allied
Pascopyrum 5^2 ^f/i^r- "dominated" communities) from the community under consideration.

Element Distribution
Range: Tliis needlegrass - grama grass prairie community is common in the nortliern and cential Great Plains of
tlie United States and Canada, ranging from Manitoba west to Alberta, south to Kansas and possibly Colorado.

States/Provinces: AB:S?, CO?, KS:S?, MB:S3, MT:S?, ND:S3?,NE:S?, SD:S?, SK:S?, WY:S3

Element Sources
Authors: J. Drake, MCS; mod. B. L. Heidel, MTNHP Confidence: 1 Identifier: CEGLO02O37
Referfnces: Hansen et al. 1984, Hanson and Whitman 193S, Hubbard 1950, Johnston 19S7, Looman 1980,
Mueggler and Stewart 1930, Steinauer and Rolf smeier 2000, Thilenius et al. 1995, Tolstead 1941, Tolstead 1942,
Weaver and Albertson 1956

Hesperostipa comata - Carex filifolia Herbaceous Vegetation
Needle-and-Thread - Tine adleaf Sedge Herbaceous Vegetation

Element Concept
Envlionment:

hi Powder River County, MT this plant association occurs on sandy, nearly-level uplands scattered along tlie
Powder River and on top of isolated, sandstone-capped buttes and ridges.

Vegetation:

GRank & Reasons: G4 (96-02-01).

Appendix E-29

Comments: In Montana this plant association appears to correspond with a subset of environmental conditions for
tlie Hesperoshpa comata - Bouteloua gracilis - Carex filifolia plant association.

Element Distribution
Range: In Montana, tliis plant association is reported fiom the Sioux District of Custer National Forest as well as
national grasslands in South Dakota (Hansen and Hoffman 19SS).

States/Provlnces: MT:S4

Element Sources
Anthers: WCS; mod. B. L. Heidel, MTNHP Confidence: 2 Identifier: CEGL001700
References: Bourgeron and Engelking 1994, Driscoll et al. 1984, Hansen 1985

V.A.5.N.C.27. PASCOPYRUM SMITHII HERBACEOUS ALLIANCE

Pascopyrum SMITH II - Bouteloua gracilis - Carex filifolia Herbaceous Vegetation
Western Wheatgrass - Blue Grama - Tlireadleaf Sedge Herbaceous Vegetation

Element Concept
Snmmai'y: This western wheatgrass prairie commimity occius throughout much of the northwestern Great Plains
of the United States and Canada, on flat or genfly sloping terrain. Many stands are on floodplains or gentle valley
slopes. Some are on uplands. The soils are clay loam, silt loam, or loam andnsnally deep and fertile. Tliis
commimity is dominated by medinm and short graminoids. The midgrass stratum is dominated by Pascopyrum
sniithii or Elynius lanceolatus. Common associates include Koelena mcicrantha, Hespevostipa comata (= Stipa
comata}^ and Nassella vividula. Hespevostipa comata is more common on the upper slopes and drier upland sites
with sandier soils, whereas Nassella vtridida is more common on the lower slopes and floodplains with flner-
textnred soils. Tlie most common short graminoid is Bouteloua gracilis. Other common graminoids include Carex
filifolia. Carex mops ssp. heliophila^ Carex duriuscula (= Carex eleochavis), and Carex pensylvanica. Forbs do
not contribute much of the canopy cover but they are scattered tliroughout this community. Topical forbs are
Tragopogon dubms. Gaura cocanea, Hedeoma hispida. Phlox hoodii and Sphaeralcea coccmea.

hi Montana, tliis association occurs as a prevalent plant association across eastern plains landscapes and at all
smaller scales on fine-textured soils. It has Pascopyrum sraithu composing a significant portion of the canopy
cover, representing mid-height stature and rhizomatous growth form, unless suppressed under dionglit cycles.
Short stature graminoids (grasses and sedges) compose equal or greater cover tlian the canopy of mid-height
grasses.

Envli^onment: Tliis community is found on flat or gently sloping terrain. Many stands are on floodplains or
gentle valley slopes, others are on uplands. Surface layers of soils arensually clay loams, althongli stands of this
type may also be found on loams, silt loams, silty clays and clays (Hanson and Whitman 1938, Hansen and
Hoffinan 1988). hi Alberta and Saskatchewan this association grows on solonetzic soils (with an ehivial horizon
above a dense clay horizon high in sodium salts) developed on thin glacial till over Cretaceous shale (Coupland
1961). Tliis commimity does not appear to be foimd in monntain valleys (Hanson and Dahl 1956, Jones 1992).

In Montana, this community occurs on deep-soil settings of the plains on loams, silt loams, and clay loams, with or
without impeded diainage. It spans the fiill range of topographic positions in its cuirent vegetation definition,
while sorting by topographic position and permeability depending on species dominance phase. This association
and the Hesperostipa comata - Bouteloua gracilis - Carex filifolia Association (CEGL002037) could be considered
the most common plant associations in the Northern Great Plains {Martin et al. 1998). Tliese two associations,
cited by many anthors as the climatic climax commimities for this region, are manifested by matrix or large patch
occurrences fieqiiently found dominating whole landscapes. The Hesperostipa con\ata defined community is more
associated with uplands and the Pascopyrum smithii defined type characterizes sites with higher moisture status,
generally occiuring at lower positions in the landscape.

Appendix E-30

In Powder River County, tlie association occurs on gentle slopes ranging &om 0-35 % and it is characteristic of the
widespread Silty Ecological Site of the 10-14 inch precipitation zone. It is prevalent on geutler slopes within the
Elso-Midway-Tlmrlow aud the Elso-Remmit-Ocean Lake soil associations derived from calcareous shales. It also
occurs on Silty Ecological Sites on well-diained deep-loam soils of tlie Elso - Oceau Lake association to the north.
It is occasional on upland and bench positions witli suitable substrate iu the Ringhng-Cabba -Midway association to
tlie west, a Clayey Ecological Site of tlie 15-19 inch precipitation zone.

Vegetation: Tliis community is dominated by medium and short graminoids. Total vegetation cover is usually
liigh (Hanson and Dahl 1956, Hansen et al. 1984). Pascopyrum smithu or Elymus lanceolatus or both (the two
species are similar both morphologically and ecologically) and Bonteloiia gracilis usually contribute the most
cover; however, Bouteloua gracilis cover may vary from codominant to locally absent. Carex fill folia . Carex
dwiuscida (= Carex eleochans), and Carex pensydvanica are often secondary species, but they also vary from
moderate cover to locally absent. Hesperostipa comata (= Stipa coraata} usually is present as a secondaiy species,
but it ofren codominates on sandy loam soils. In Alberta and Saskatchewan, Hesperostipa cwtiseta {= Stipa
spartea var. curtissta) may be as common as Hesperostipa comata. Koeleria macrantha is present in most stands
and may contribute substantial cover. The forbs most likely to be foimdin this association are Phlox hoodn,
^haeralcea coccinea, Polygomin\ ramosissimum, Plantago patagomca, Opiintia poly acantha, Artemisia frigida,
Antennana mici'ophylla, and Hedeon^a hispida. In southeastern Montana, western North Dakota, and northeastern
Wyoming, stands of this association often contain Artemisia tridentata ssp. wyorauigensis. Exotic brome grasses,
especially Bromiis commutatus and^ronius tectorum^ are present in many stands of this association and they
commonly contribute substantial cover (Hanson and Dahl 1956, Coupland 1961, Hansen et al. 1984, Hansen and
Hoffinanl988).

In Montana, this association occurs as a prevalent plant association across eastern plains landscapes and at all
smaller scales on frne-textured soils. It has Pascopyrum smithii composing a significant portion of the canopy
cover, representing mid-height stature and rhizomatous growth form, unless suppressed under diouglit cycles.
Short stature graminoids (grasses and sedges) compose equal or greater cover tlian the canopy of mid-height
grasses.

We note that in Powder River County, all combinations of species as co-dominants have been documented.
Buchloe dactyloides is also a recurring co-dominant to add to the plant association description. Li places co-
dominated by Pascopyrum smithii and Buchloe dactyloides^ the cover of grasses was high under good range
conditions (greater than 70%) and the cover of forbs was low, often including one or more of the following:
Agoseris glauca, Hedeoma hispida, Lomatium foeniculaceum, Linum australe, Psoralea argophylla, and
^haeralcea coccinea. Under degraded range conditions, the cover of annual bromes, Vulpia octoflora and Poa
secunda increased, and tlie cover of Pascopyrum smithii decreased. Forb cover was significant only under
degraded conditions, with such non-native or increaser species ?[%Alyssum desertorum, Camelina sativa, Opuntia
polyacantha and Plantago eriopoda. In the course of this study, we took ten plots and extensive field notes, with
particular emphasis on documenting the vegetation co-dominated by Pascopyrum smithii and Buchloe dactyloides
that was extensive on BLM lands.

Dynamics: In the past, fire likely occuixed commonly in this type. Vast (singly and in the aggregate) prairie dog
(Cynor^ys ludovicianus) "towns" once developed on tlie favorable substrates of this type and exploited its
vegetation. Prairie dog populations have undergone a precipitous decline since settlement, so much of this type
could be in various states of secondary succession, returning fiom a somewhat denuded state and altered
composition created by the prairie dogs (and attendant bison that found nutritious forage here). Fire, both
aboriginal- and lightening-caused, was a regular part of tiiis landscape. Fire -return intervals have been
considerably lengthened since settlement by European -Americans.

GRsink & Reasons: G4 (96-02-01). Tlie G4 rank is based on the broad geographic range of this type, and its
status as a common vegetation type within that range. Heavy grazing and lack of fire tiiroughout its range may
cause many stands to have a high proportion of exotics.

Higli-rsinked sprcies: Check for correlation witii black-tailed prairie dog towns in the area.

Appendix E-31

Comments: Almost any combination of Pascopyi'iim snitthii, Bouteloua gracilis, Carexfihfoha^ and Hesperostipa
comata (= Stipa comata) can be fonnd in the northern and northwestern Gieat Plains, and the relative amounts of
these species apparently depend at least in part on soil texture and grazing histoiy. Moreover, drought or wet
weatlier can cause the relative amounts of these species in one stand to change markedly in a few years (Ellison
andWoolfolk 1937, Weaver and Albertson 1956). Consequently, differentiating between plant associations based
solely on the relative amounts of these species is extremely difficult. This Pascopymm smithu - Bouteloua
gracilis - Carex ftltfoha association is found on soils in textural classes finer tlian loam in which Pascopyrum
sratthii and/or Elymus lanceolatus (which is similar morphologically and ecologically) contribute at least as much
cover as does Hesperosttpa comata. Bouteloua gracilis, Elymus lanceolatus and Carex filifolia may be patchily
distributed, so areas of several acres should be examined to determine whether the vegetation belongs to this
associafion. This association shares major graminoid species with Hesperostipa comata - Bouteloua gracilis -
Carex fill foil a Herbaceous Vegetation (CEGL002037) but in the latter association, Hesperostipa comata
contiibutes more cover than do Pascopyrum smithti or Elymus lanceolatus^ and the latter association grows on
soils of loam or coarser texture.

Recognition of this plant association in Montana is comphcated by four factors. 1) There is a basic question on
delimifing tlie Pascopyrum smithu Alhance as separate fi'om the Hesperostipa comata - Bouteloua gracilis
Alhance and possibly others. The classification work to date has amassed information fiom the hteratiire that
includes different standards of measure (basal cover vs. canopy cover) as well as different climate cycles.
Classification within the ''wheatgrass-needlegrass" domain of Kuchler (1964) may result in different dominance
types depending on whether defined by canopy dominance or basal cominance. 2) Tlie inter changeability and
ecological equilivence of Pascopyrum smithn and Elymus lanceolatus and the similar needlegrass species-pair has
not been analyzed in detail. They sort by lafitude in their distribution and tlieir tendency to have different
environmental modes where they occur together waiiants extended documentafion. Note: Elymus lanceolatus is
uncommon in Powder River County compared to Pascopyrura smithu. It is most common on overflow outwashes
andpanspots. 3) There are many different expressions of the plant association that have been well -documented. Li
one of its most widespread foiins, Hesperostipa comata is associated with Pascopyrum smithu and Bouteloua
gracilis. In the Ashland District of Custer National Forest, Pascopyrum smithii is associated with Carex fdi folia
(Hansen and Hoffman 19SS). In broad, hot aUuvial flats, there are reports of Pascopyrum smithii occurring
repea t ably wi til Bouteloua gracilis (Heidel et al. 2000). Given the current concept of this type, they all fit within
tlie type, but not all of their environmental characteristics fit. 4) Tlie codominance of Buchloe dactyloides with
Pascopyrum sruthu^ as documented on BLM-administered lands in much of Powder River County, has not been
well-docmnented in the noithern Great Plains. Vegetation dominated by Pascopyrum smithu, Buchloe dactyloides
and Bouteloua gracilis vias briefly described in the South Dakota Badlands (Tolstead 1941), and mapped
accordingly by Kuchler (1964). It is widely accepted that heaiy grazing favors increased cover of Buchloe
dacytloides, as demonstiated on clay range sites at the Fort Keogh Livestock and Range Experiment Station of the
noithern Gieat Plains (Reed and Peterson 1961), as well as in the central and southern Great Plains.

In Powder River County, the two species are ubiquitous on silty range sites. The cover values of Pascopyrum
snuthii typically ranged fiom 20-30%, but in moisture-collecting settings and successional conditions, may exceed
50%. The cover of Buchloe dactyloides were typicaUy aroimd60%. It superficially resembled blue grama
{Bouteloua gracilis), fiom which it differs in vegetative reproduction by stolons, dioecious spikelets, and leaf
siuface characteristics. The latter was not present above a trace in plots with this association. Tlie cover of
individual native forb species was only a trace.

hi Powder River County, we documented co-dominance of Pascopyrum smithu and Buchloe dactyloides as
prevalent on eastern plains. Co-dominance of Pascopyrum suiithii and Carex filifolia has been documented on
ridge systems to the west (Hansen and Hoffman 19SS) and we documented co-dominance of Pascopyrum smithii,
Hesperostipa comata and Bouteloua gracilis with changes in substrate to the north.

Element Distribution
Range: Tliis western wheatgrass prairie commimity occurs throughout much of the nortliwestem Great Plains of
tlie United States and Canada on fiat or gently sloping teiiain, ranging fiom Alberta and Saskatchewan in Canada
south to Nebraska and possibly Colorado.

hi Powder River County, there are extensive areas of fine-textured soils where this is the prevalent plains plant

Appendix E -3 2

associatiou.

States/Provinces: AB:S?, CO?, MT:S4, ND:S3?,NE:S3S4, SD:S4, SK:S?, WY?

Element Sources
Authors: H.C. Hausoii and W. Whitman, mod J. Drake aud D. Faber-Langendoen, WCS; mod. B. L. Heidel,
MTNHP Confidence: 2 Identifier: CEGL001579

References: Bourgeron andEngelking 1994, Driscoll el al. 1984, Ellison andWoolfolk 1937, Hansen 1985,
Hansen and Hof&nau 198S, Hansen et al. 1984, Hanson audDahl 19_^6, Hanson aud Whitman 1938, Johnston
1987, Jones 1992b, Kuchler 1964, Ode pers. conim., Steinauer aud Rolfsmeier 2000, Weaver aud Albertson 1956

Pascopyrum SMiTHii Herbaceovs Vegetation
Western Wheatgrass Herbaceous Vegetation

Element Concept
Sumniai'y: This midgrass prairie type is found in tlie northern and western Great Plains, Rocky Momitains, and
tlie interior western United States andpossibiy Canada. Stands occur on level to gently sloping terrain. They are
found on alluvial fans, swales, river terraces, floodplains, valley floors and basins. The soils are clay, clay loam,
aud sill loam. Pa:^copyrum smithii strongly dominates the moderate to dense (40-100% cover) mixedgrass
herbaceous canopy that grows 0.5-1 m tall. Other graminoids tliat co-occur aud may achieve local dominance are
Koelena macrantha. Eleochans palnstns, ^ndPoa spp. Many other species common in midgrass prairies are also
found in this commiuiity. These mcXvidt Artemista ludoviciana, Enogonum spp.» Bouteloua gracilis, Nassella
vwidida^ and Hesperosttpa comata (= Stipa comata). Shrubs and dwarf-shrubs are rare in this community, but
occasional woody plants such ?[%Artemisia tridentata, Symphoncarpos spp., EncamehQ naii:^eosa, or
Kraschenmmkovia lanata may be present. Introduced species, such as Bromus tectorum, Bromus inermts, Poa
pratensis, Melilotus spp, or Cirsium aiyense, are common in some stands, especially where disturbed.

Envli^onment: Tliis grassland association is widespread in the nortliern and western Great Plains, Rocky
Mountains, the intermountain western United States and possibly Canada. Elevation ranges fiom 600-3000.
Stands occur on level to gently sloping terrain. Tliey are found on alluvial fans, swales, river terraces, floodplains,
valley bottoms and basins. Tlie soils are deep (40-100 cm) and well -developed with clay, clay loam, and silt loam
textiues. Some stands occur on perched water tables.

Vegetation: This association is characterized by a moderate to dense (40-100% cover) mixedgrass herbaceous
canopy that grows 0.5-1 m tall and is strongly dominated by Pa:^copy rum smithu. Other graminoids that co-occur
and may achieve local dominance are Koelena macrantha, Eleochans palustns^ and Poa spp. Many other species
common in midgrass prairies are also found in this community. TTiese incXud^Artemma fngida, Artemisia

ludoviciana, Achillea sp., Carex spp., Enogonum spp., Bouteloua gracilis. Nassella viridula, and Hesperostipa
comata (= Stipa comata). Slirubs and dwarf-shnibs are rare in this community, but occasional woody plants such
as S\-mphoricarpos spp., Encamena nauseosa, or Krascheninnikovia lanata may be present. Introduced species,
such as Bvomiis tectorum, Bromiis inermis, Poapratensis, Melilotus spp., drsmm arvense. Taraxacum officinale^
or Salsola kali^ are common in some stands^ especially where disturbed.

Dynamics: In semi-arid chmates, this association is found in relatively mesic topographic positions such as
swales, river terraces, floodplains and basins that may be temporarily or intermittently flooded or in some classes,
tlie fine textiued soil sometimes perches the water table (Hansen et al. 1995, Hansen and Hall 1997). In more
mesic climates it is found in extensive upland areas.

GRank & Reasons: G3G5Q (96-02-01).

Comments: Tliis community is similar to several others that are dominated or codominated by Pascopyrum
smithii. As currently defined, it represents a western Giieat Plains and foothills version of the western wheatgrass
types in the central Great Plains. Further work needs to be done to refine tlie differences in composition and
enviionmental characteristics. See recent descriptions by Thilenius et al. (1995) {Pascopyrum smithii sodgiass

Appendix E -3 3

steppe, a more playa-like wheatgrass type) and by Steiuauer and Rolfsmeier (2000). Li Nebraska, Steiuauer and
Rolfsmeier (2000) suggest that their stands may resemble Pascopyrum smithu - Nassella vindula Herbaceous
Vegetation (CEGL001583).

Element Distribution
Range: Tliis midgrass prairie type is found iu the northern and western Great Plains, Rocky Moimtaius,
intennoimtaiu western United States aud possibly Canada, ranging from Nortli Dakota and possibly Saskatchewan,
south to Nebraska and Colorado, west to northern Arizona, Utah and Idaho.

States/Provinces: AZ:S?, CO:Sl?, ID:S1Q, MT:S4,NE:S?, SD:S?, SK:S?,UT:S3S5, WY:S4Q

Element Sources
Anthers: I.E. Drake, mod. K. Schiilz, WCS Confidence: 3 IdentlTier: CEGL001577
Referfnces: Aldous and Shantz 1924, Baker 1983c, Baker 19S4a, Baker and Kennedy 1985, Bourgeron and
Engelking 1994,Bnnin 1985, Christensen and Welsh 1963, DriscoU etal. 1984, Godfread 1994, Hall and Hansen
1997, Hansen etal. 1991, Hansen etal. 1995, Jones and Walford 1995, Marr and Buckner 1974, Ramaley 1916b,
Ramaley 1919b, Ramaley 1942, Shanks 1977, Soil Consei-vation Service 1978, Steinauer and Rolfsmeier 2000,
Tliileniiiset al. 1995, Von Loh 2000

V.A.5.N.C.20. SCHIZACHYRIUM SCOPARIUM - BOUTELOUA CURTIPENDULA
HERBACEOUS ALLIANCE

SCHIZACHYRIUM SCOPARIUM - BOUTELOUA {CURTIPENDULA, GRACILIS)- CAREX FILI FOLIA

Herbaceous Vegetation

Little Blueslem - (Sideoats Giama, Blue Grama) - Tlneadleaf Sedge Herbaceous Vegetation

Element Concept
Suinmai'y: This little bluestem - mixedgrass prairie type is distributed tliroughout the northern Great Plains of the
United States and Canada. Stands are usually found on moderate to steep slopes with variable aspects. The soils
are typically shaUow and occur over sandstone or limestone. Tlie vegetation is predominantly composed of
graminoid species less than 1 m tall with moderate to higli cover. Tlie dominant species is Schizachyrium
scopanum with Bouteloua curtipendula, Bouteloua gracilis^ and Cavex filifolia as associates or codominants.
A\i6i opogon gerardii, Carex inops ssp. heltophila, Cavex dunuscula^ Koeleria maci'antha, and Calauiovilfi
longifolta are often present. Calamovtlfa longifoha may be abundant on sandier soils. Muhlenbergia cuspidata,
Hesperostipa comata {= Stipa coraata), Pascopyrum smithu, and Nassella vindida may also be present. Forbs do
not contiibute greatly to the canopy, but many species may be found in this community. Among the forbs that may
be found are Echinacea angustifoha, Symphyotrichum oblongifolium (= Aster oblongifoluis), Gaura cocanea,
Lygodesmia juncea, Helianthus paiLciJlonis ssp. pauciflorus, Rosa arkansana, Ltatns punctata, Pediomehim
argophyllum, Symphyotrichum ei'icoides (= Aster ericoides), Dalea purpurea^ and Campanula rotundtfolia.

Envli^onment: Tliis community is usually found on gentle to steep slopes with variable aspects (Hansen et al.
1984, Johnston 19S7, Hansen and Hoffiuan 198S). Tlie soil may be loamy sand, sandy loam, loam, or clay loam.
Tliere may be a substantial component of gravel. Hansen et al. (19S4) found 7-36% gravel by weight in 16 stands
in western North Dakota. The soils are typicaUy shallow and occur over sandstone or hmestone (Johnston 1987,
Tliileniuset al. 1995).

Vegetation: Tliis community is predominantly composed of graminoid species less tlian 1 m tall. Finus
pondevosa may occasionally be present. Tlie vegetation cover is moderate to high. Thilenius et al. (1995) found
that vegetation cover was 44% in Wyoming, and Hansen andHoffinan (1988) found 75% cover in Nortli Dakota.
Tlie dominant species is Schizachyrium scopanum, with Bouteloua curttpendula, Bouteloua gracilis, and Carex
filifolta as associates or codominants. Awdn'opogon gevardii, Cavex inops ssp. hehophila, Carex duriuscula (=
Carex eleochans), Koelena macrantha and Calamovilfa longifoha are often present. Calamovilfa longifoha may
be abundant on sandier soils. Muhlenbergia cuspidata, Hesperostipa comata (= Sttpa comata), Pascopyrum
snnthii, and Nassella vindula may also be present. Pssudoroegneria sptcata may be found in the western portions
of this community (Jones 1992). In Manitoba, the graminoids Festuca ovina and Elymfis trachycaulus and the

Appendix E -34

liclieu Selagmella densa are more abimdaut (Greeuall 1995). Forbs do not couhibute greatly to the canopy, but
many species may be foimd in this community (Hanson and Whitman 1938). Among the forbs that may be fouud

are Echinacea ctrtgiistt folia, Symphyotnchum oblongifolmm {= Aster oblortgifoluis), S\-mphyotrtchiim encotdes {=
Aster ericoides), Gaura coccmea, Lygodesmia juncea, Hehanthits pauctflorus ssp. paucifiorus^ Rosa arkansana,
Liatris punctata, Pediomelum argophylhim (= Psoralen avgophylla). Dalea purpurea. Phlox hoodn, and
Campanula rotundifolta . Tliere are very few woody species; those that are present are usually short shrubs siich as
Artemisia fngida. Jumperus horizontalis, Tind Yucca glauca. Litter often accimiulates and may cover more than
50% of the ground (Hirsch 19S5).

Dynamics: Fire probably played a major role in this type, whereby peiiodic fires would increase graminoid
production and deter tree growth.

GRank & Reasons: G3G4 (99-09-09).

Comments: Contrast this association with Schizachyrmm scopartum - Bouteloua cwttpendula grasslands in New
Mexico. Hansen et al. (19S4) report that Bouteloua gracilis and Koeleria macrantha (= Koelerta cnstata) may be
prominent in Theodore Roosevelt National Park, North Dakota.

Element Distribution
Range: This httle bluestem mixedgrass prairie type is distribnted throughout the northern Great Plains of the
United States and Canada, ranging fiom Manitoba and possibly Saskatchewan, south to South Dakota and
Wyoming.

States/Provinces: MB:S?, MT:S?,ND:S3?, SD:S?, SK:S?, WY:S3

Element Sources
Anthers: P.L. Hansen, G.R. Hoffinan, and A.J. Bjugstad, mod. J. Drake andD. Faber-Langendoen, WCS; mod.
B.L. Heidel,MTNHP Confidrnce: 2 Identlfifi: CEGL001681

Referfnces: Bourgeron andEngelking 1994, Butler and Goetz 19S6, Driscoll et al. 19S4, Greenall 1995, Hansen
1985, Hansen and Hoffman 1988, Hansen et al. 1984, Hanson and Whitman 193S, Hirsch 1985, Johnston 1987,
Jones 1992b, MTNHP 1988, McAdams et al. 1998, Tliilenius 1972, Tliilenius et al. 1995

V.A.5.N.C.35. SCHIZACHYRIUM SCOPARIUM HERBACEOUS ALLIANCE

SCHIZACHYRIUM SCOPARJUM - CAREX INOPS 3SP. HELIOPHILA HERBACEOUS VEGETATION

Little Bluestem - Snn Sedge Herbaceous Vegetation

Element Concept
Summary:

Environment: In Powder River County, this plant association is found in Sandy Ecological Sites, 10-14 inch
precipitation zone.
Vegetation:
Dynamics;

GRank & Reasons: 03(96-02-01).
Comments:

Element Distribution
Range:
States/Provinces: MT^S3

Element Sources
Authors: WCS; mod. B. L. Heidel, MTNHP Confidencf : 2 IdentiTier: CEGL001682
References: Bourgeron and Engelking 1994, Culwell and Scow 1982, Driscoll et al. 19S4

Appendix E-35

V.A.S.N.d. Medium -tall bunch temperate or subpolar grassland
V.A.5.N.D.8. FESTUCA IDAHOENSIS HERBACEOUS ALLIANCE

FESTUCA IDAHOENSIS - CAREX INOPS 3SP. HELIOPHILA HERBACEOUS VEGETATION

Idaho Fescue - Sim Sedge Herbaceous Vegetation

Element Concept
Summai'y: Festuca idahoensts - Carex mops ssp. heliophila Herbaceous Vegetation is found in the northern
Great Plains on upland plateaus and in open areas surrounded by ponderosa pine forest. It is found on moderate
slopes (5-15%) of all aspects at around 1200 ni elevation. Soils tend to range fiom loam to sandy loam. Festiica
idahoensis is clearly dominant, and Carex inops ssp. heliophila (= Carex heliophila) is constant and abundant.
Also usually present are Koelena macrantha (= Koeleria pyramidata), Artemisia hidovictana, Symphyotnchum
encoides (= Aster ei'icoide^), nud Pascopy rum ^mithii (=Agropyron smithti), Hesperostipa comata (= Stipa
comata) is often present but only as a minor component of the vegetation.

Envii^onment: Tliis herbaceous vegetation type is found on moderate slopes (5-15%) of all aspects at aromid 1200
m elevation. Soils tend to range &om loam to sandy loam.

Vegetation: Shnibs and forbs are present, but this type is clearly dominated by giaminoids, with Festuca
idahoensis being tlie most prominent species. There is often some exposed soil.

GRank & Reasons: G3 (96-02-01).

Comments: Tliis vegetation type was documented on an imglaciated landscape and may not occur on the
glaciated portions of the Gieat Plains. Festuca idahoensis - Carex inops ssp. heliophila Herbaceous Vegetation
(CEGL001610) is separated from Hesperostipa comata - Carex mops ssp. heliophila of Hansen andHoffinan
(19SS) by tlie predominance of Festuca idahoensis and by the lack of significant cover of Hesperostipa comata (=
Stipa comata). Tlie Festuca idahoensis - Carex inops ssp. heliophila type also has less forb coverage, less leaf
htter and more exposed soil (ibid.). Several studies have documented Festuca idahoensis types that have Carex
spp. as a dominant associate. Generally however, the species of Carex noted as predominant is different. Carex
obtiisata is listed as a main component for a number of types (Hansen and Hoffman 1988). Mueggler and Stewart
(1980) note a Festuca idahoensis - Carex filifoha habitat type.

Element Distribution
Range: Tliis community is found in Montana.
States/Provinces: MT:S3

Element Sources
Authors: WCS Confidence: 1 Identifier: CEGL001610

Referfuces: Bourgeron and Engelking 1994, Driscoll et al. 1984^ Hansen 1935^ Hansen and Hoffinan 1988,
Mueggler and Stewart 1980

VA.5.N.D.22. PSEUDOROEGNERIA SPICATA HERBACEOUS ALLIANCE

PSEUDOROEGNERIA SPICATA - BOUTELOUA CURTIPENDULA HERBACEOUS VEGETATION

Bluebunch Wlieatgrass - Sideoats Grama Herbaceous Vegetation

Element Concept
Summai'y: This mixedgrass association ranges in size fiom small to large patches which are located on foothills
and sideslopes along major diainages between the Tongue and Powder rivers of southeastern Montana. This type
is considered a topo-edaphic climax by Hansen and Hoffinan (1988) because it occurs on moderate to steep
(>45%) slopes the surfaces of which are stiewn with large amounts of irregularly shaped, iron oxide porcelainite
shale (scoria). Tlie surface resulted from fires in contiguous coal beds (but the soils are conventional loams). Tlie
harsh sites of this type result in a imique depauperate community wilh the lowest total cover and graminoid cover
of any southeastern Montana type inventoried by Hansen and Hoffinan (1988). However, it still has greater cover

Appendix E-3"j

audis more productive than those communities associated with bentoiiite deports and acid shales.

Psendovoegnena spicata is strongly dominant {canopy cover ranging fiom 40-60%) with Bouteloua curhpendula
exhibiting less than one- fourth tliis value. Pascopyrnr-i snuthn (= Agropyvon smithu) ^nd Schizachynuni
scopanum are consistently present with cover less than 10%. Forbs are a minor component with Lygodesmia
juncsa. Echinacea angusttfoha and Pediomelum argophyllum (= Psoralen aigophylla) having the highest fidelity
to the type.

Envii^onment: Tliis type occurs as small to large patches located on footliills and sideslopes along major
diainages between the Tongue and Powder rivers of southeastern Montana; known elevations range between 3100
and 3800 feet. Tliis type is considered a topoedaphic climax by Hansen and Hoffinan (19S3) because it occurs on
moderate to steep (>45%) slopes, the surfaces of which are strewn with large amounts of irregularly shaped, iron
oxide porcelainite shale (scoiia) that has resulted &om ancient fires in contiguous coal beds. Tlie soils are
conventional loams but shallow and excessively drained.

Vegetation: Pseudoroegneria spicata is shongly dominant (canopy cover ranging fiom 40-60%) with Bouteloua

cuvtipendula exhibiting less than one-fourth this cover value. Pascopyrum sraithu (= Agropyron smithu) and
Schizachyrium scoparmra are consistently present with cover less than 10%. Forbs are a minor component with
Lygodesmia juncea, Echinacea angustifoha and Pediomelum argophyllum (= Psoralea argophylla) having tlie
highest fidelity to the type. The shmbs (siibshrubs) Rhus trilobata, Gutierrezta sarothvae ^nd Artemisia fngida are
consistently present with low coverage values (less than 5%).

Dynamics: Given the low cover and patchiness of this type, fires probably burned in a mosaic fashion with
reduced intensity. Pronghorn antelope use these sites for grazing and predator detection.

GRank & Reasons: G3 (99-12-01). As cuirently understood, this type is reshicted both geographically and with
regard to site parameters. However, appropriate habitat in Wyoming overlaps the distribution of the characteristic
species, so inventory may yield more occurrences. Tlireats to this type could potentially come fiom domestic
stock, but sites are generally somewhat removed fiom water. These sites are generally not conducive to alien
Bromus species, but their potential to support otlier weeds is unknown.

Comments: Pseudoroegneria spicata - Bouteloua curtipendula appears to be endemic to southeastern Montana,
occiuring between the Tongue and Powder rivers. Other portions of southeastern Montana and adjacent Wyoming
would appear to have appropriate habitat (soils derived fiom scoria chnker) but lack populations of Bouteloua
curtipendula or Pseudoroegneria spicata because they are at the extreme western and eastern extensions of their
respective ranges and consequently sporadically distributed. There would seem to be some sites intennediate
between Rhus trilobata /Pseudoroegneria spicata Shmb Herbaceous Vegetation {CEGL001120) and this type and
for which it would be helpful to have an arbitrary cover cutoff value for Rhus trilobata for assigning stands to
types. In the Rapid Ecological Assessment of the Northern Great Plains this type was recorded but once (Martin et
al. 1998). Rhus trilobata /Pseudoroegneria spicata Shrub Herbaceous Vegetation (CEGL001120) differs fiom
this community by having Rhus trilobata dominant or at least well represented. Pseudoroegneria spicata - Carex
filifolia Herbaceous Vegetation (CEGL001665) differs from this association by lacking Bouteloua curtipendula
and having Carex filifolia witli at least 5% cover, tliough it may not be the dominant graminoid. Pseudoroegneria
spicata - Bouteloua gi'acihs B.evhAceoiis Vegetation (CEGL001664) of western Montana occurs for the most part
west of the distribution of Bouteloua curtipendula and where Bouteloua gracilis is the imdergrowth dominant.

Element Distribution
Range: Tliis association has been recorded for only southeastern Montana, tliough appropriate habitat ostensibly
occurs in northeastern Wyoming and westernmost North Dakota.

States/Provinces: MT:S3,ND:S?, WY?

Element Sources
Authors: S.V. Cooper, WCS: mod. B. L. Heidel, MTNHP Confidence: 2 Identifier: CEGL001663
References: Bourgeron andEngelking 1994, Driscoll et al. 1984, Hansen 1985, Hansen and Hoffinan 1988

Appendix E-37

PSEUDOROEGNERIA SPICATA - CAREX FILIFOLIA HERBACEOUS VEGETATION

Bhiebiiuch Wheatgrass - Tlireadleaf Sedge Herbaceous Vegetation

Element Concept
Suinmai'y: Staud^ of this association occur on level or gently sloping upland sites with loam or siUloani soils.
Tliis is au herbaceous vegetation type iu which graminoids contribute most of the cover. A number of forbs may
be present, but forbs and shmbs contribute httle covei to the vegetation. Pseiidoroegnena spicata dominates the
vegetation, and Carex filifoha contributes substantial cover. Small amounts of Bouteloua gracilis maybe present.

Envii'onment: Stands of tliis association have been described from nearly level sites (some windswept) with loam
and silt loam soils. Elevations range from about 4100 feet on the Great Plains to about 7000 feet on the west flank
of the Bighorn Mountains.

Vegetation: Graminoids contribute most of the cover, and forbs are secondary; shrubs may be present as scattered
individuals or clumps that contribute little cover to the vegetation. Pseudoroegnena sptcata dominates the
vegetation, and Carex filifoha contributes substantial cover. Hespej'o^tipa comata (= Stipa comata), Koeleha
macrantha^ and Carex mops ssp. heliophila (= Carex heliophdn) (in Great Plains stands) often are present in
smaUer amounts, but they may contribute as much cover as does Carex fill foh a. Bouteloua gracilis is absent or
present only in small amounts. Cheatgrass {Bromus japomciis. Bromus tsctorum) is present in many stands and
may contribute nearly as much cover as does Pseiidoroegnevia spicata. The vegetation may contain small amounts
of numerous forbs. Shrubs are absent or present only as scattered individuals {t^t\:\?[[\y Artemisia tridentata ssp.
wyomingensis), but the ^ibKhvubs Artemisia fngi da and Gutierrezia sarothrae usually are present in small
amounts.

GRank & Reasons: G4 (96-02-01)

Comments: Tliis association seems to resemble very closely, in environment and vegetation, the more widespread

Pseudoroegnena spicata - Bouteloua gracilis Herbaceous Vegetation {CEGL001664), except that this association
contains little or no Bouteloua gracilis. The geographic ranges of tlie two associations overlap, and it is unclear
whether good reasons exist to differentiate the two.

Element Distribution
Range: This association has been described from two stands in soutlieastern Montana (Hansen and Hoffman
1988) and from two stands (Fisser 1964) and cursory information (Despain 1973a) in north-central Wyoming.

States/Provinces: MT:S4,WY:S?

Element Sources
Authors: WCS Confidence: 1 Identifier: CEGL001665

Referfnces: Bourgeron andEngelking 1994, Cotter- Fergus on Project n.d., Despain 1973a, DriscoU et al. 19S4,
Fisser 1964, Hansen 1985, Hansen and Hoffman 1983, Johnston 1987

PSEUDOROEGNERIA SPICATA - PASCOPYRUM SMITHII HERBACEOJJS VEGETATION

Bluebunch Wheatgrass - Western Wheatgrass Herbaceous Vegetation

Element Concept
Summai'y: This grassland association is found in the northern Gieat Plains and in the eastern foothills of the
northern U.S. Rocky Mountains. Stands generally grow on slopes with shallow soils. Pseudoroegnena spicata
dominates tlie vegetation, and rhizomatous wheatgrasses {Pascopyj'iir\i smithii or Elyr\ius lanceolatus) are
abundant. Forbs and shrubs contiibute little cover.

Envii^onment: Stands of tliis grassland association grow over a broad elevation range, fiom 2600 feet in Great
Plains to 7500 feet in the foothills of tlie Rocky Mountains. Tliey occur on slopes, from gentle alluvial fans to
slopes as steep as 40%, facing all aspects. Substiates are glacial deposits, alluvium, limestone, and calcareous
sandstones. Soils usually are shallow, may contain a substantial volume of coarse fragments, and belong to sandy

AppendixE-3S

clay loam, loam, or clay loam textiiial classes. The sites often are exposed to strong, persistent winds.

Vegetation: Grasses contribute most of the cover and production. Pssudoroegnena spicata dominates (usually
sti'ougly). Tlie rhizomatous wheatgrasses Pascopyrum smithii or Elymus lanceolatus (or both) are secondary
species, but the rhizomatous wheatgrasses may codominate with Pseudoroegnena spicata. Hesperostipa comata
(= Stipa comata). Koelena macrantha^ and Poa secunda usually are present in smaller amoimts, but Hespei'o^tipa
coraata ofteu codomiuates in west-central Montana (Jorgensen 1979). Bouteloua gracilis is absent or is a minor
species. Nassella vindiila (= Stipa vindula} contributes substantial cover in some stands, especially in the Great
Plains but also in some foothills stands (Mueggler and Stewart's (1980) Stipa vwidula phase). Stands in the
footliills often contain Poa cnsichi, Leucopoa kingn^ and Calamagrostis montanertsis . In southeastern Montana
(Hansen andHoffinan 19SS) and northeastern Wyoming (Terwilliger et al. 1979a), Bouteloua curtipendula may
also occur in the vegetation. Forbs contribute little cover or production, but a mmiber of species may be present,
mQ\\\di\i% Ambrosia psilostachy a (in Great Plains stands), Draba ohgosperma, Engeron compositus, Stenotus
acanlis {= Haplopappus acauhs), Heterotheca villosa, Sphaeralcsa coccuiea. Phlox hoodii, Tragopogon dubtus,
and Vicia amencana. The ^ibshvubs At te mi sia fngi da and Gutierrezia sarothrae usually are present in small
amounts. Shnibs generally are absent or are present only as scattered individuals, but Tweit and Houston (1980)
note that Tetradynaa canescens may be common and Chiysothamnus spp. may form a distinct shnib layer in
disturbed stands.

GRank & Reasons: G4 (96-02-01).

Comments: Tlie inclusion of Hansen and Hoffinan's (19SS) stand number 25 from southeastern Montana extends
the range of variability in vegetation found in this association. That stand contains Bouteloua curtipendula as an
important species, and its inclusion in this association may be inappropriate. Similarly, it is unclear how much
Bouteloua gracilis and Carex filifolia should be allowed in the vegetation for a stand to be placed into this
association. In Pseudoroegnena spicata - Poa secunda Herbaceous Vegetation (CEGL001677), rhizomatous
wheatgrasses are absent or contribute little cover.

Element Distribution
Range: Tliis association has been described fiom western and central Montana (Jorgensen 1979, Mueggler and
Stewart 1980, Cooper et al. 1995), northeastern Montana (DeVelice et al. 1995), southeastern Montana (Hansen
and Hofhnan 1933), northwestern and west-central Wyoming (Tweit and Houston 19S0), and apparently fiom
northeastern Wyoming (Terwilliger et al. 1979a).

States/Provinces: MT:S4,WY:S3

Element Sources
Authors: WCS Confidence: 1 Identifier: CEGL001675

References: Bourgeron andEngelldng 1994, Cooper et al. 1995, DeVelice et al. 1995, DriscoU et al. 1984,
Hansen and Hofhnan 19SS, Hansen et al. 1984, Johnston 1987, Jorgensen 1979, Mueggler and Stewart 19S0,
Tei-wilhgeretal. 1979a, Tweit and Houston 1980

VA.S.N.j. Temporarily flooded temperate or subpolar grassland
V.A.5.N.J.18. PASCOPYRUM SMITHII TEMPORARILY FLOODED HERBACEOUS
ALLIANCE

Pascopyrum SMITHII - Horde UM JUBATUM Herbaceous Vegetation
Western Wheatgrass - Foxtail Barley Herbaceous Vegetation

Element Concept
Suinniai'y: This wheatgrass sahne prairie type is found in the northern Great Plains of the United States and
adjacent Canada. Stands occur in temporarily flooded sites (playas and stock ponds) with deep, poorly diained,
clayey, alkaline-saliue soils. Stands occur as small patches in temporarily flooded sites, siuTounded by grasslands
or shrublands. Grasses dominate the vegetation. Pascopyrum smithii (or Elymiis lanceolatus) and Hordeum

Appendix E-39

jubatum are the major species, and other species fiom the siirroundiug matiix vegetation may be present.

Eiivii^oninent: Stands of tliis association occupy temporarily flooded sites (playas and stock ponds) with deep,
poorly dfaiued, clayey, alkaline- saline soils. This type occurs on diawdown zones around reseivoirs in eastern
Montana (S. Cooper, MTNHP, pers. comm. 1998).

Vegetation: Grasses contribute most of the cover in this association, although forbs and scattered shrubs may be
present. Pascopyrum snuthu or Elyraus lanceolntus dominate, and Hordeiim jiibatiira contributes substantial cover.
Other species may be present but contribute little cover. Stands in south-central Wyoming contain scattered
Atnplex gardnen liom the surrounding vegetation (Medicine Bow Mine, no date).

GRank & Reasons: G4 (96-02-01). Tlie G4 rank is based on a fairly broad geographic range.

Comments: Stands apparently occupy soils with higher sodium concentrations than do stands of the similar
Pascopyrum smithti - Eleochans spp. Herbaceous Vegetation (CEGL001581) (Bergman and Marcus 1976), or
playas where the surface dries and the water table drops more quickly (BLM 1974). Tliis association has not been
described well. Further analysis of existing information and additional inventory will be helpful in detennining tlie
range of variation in stands of this type and how this type differs froia other vegetation types of temporarily
flooded sites.

Element Distribution
Range: Tliis wheatgrass saline prairie type is found in the northern Gieat Plains of the United States and adjacent
Canada, extending fiom Colorado north to Montana and possibly Saskatchewan.

States/Provinces: CO?, MT?, ND:S?, NE?, SK?, WY:S3?

Element Sources
Authors: WCS CoMidencf: 2 Identifier: CEGL001582

Referfuces: BLM 1979b, Bergman and Marcus 1976, Boiugeron and Engelking 1994, Driscoll et al. 1984,
Medicine Bow Mine Apphcation n.d.

V.A.5.N.J.11. SPARTINA PECTINATA TEMPORARILY FLOODED HERBACEOUS
ALLIANCE

SPARTINA PECTINATA WESTERN HERBACEOUS VEGETATION

Prairie Cordgrass Western Herbaceous Vegetation

Element Concept
Suinmai'y: In Colorado, this is a tallgrass meadow comprised entirely of Spartina pectinata. Stands occurs in
small swales on the plains as well as onfloodplains of larger rivers. Stands of this grass have been inchidedin
otlier tallgrass prairie plant associations. On large river floodplains, this type occurs as distinct patches and is
distinguished fiom adjacent riparian types by micro -topography and degree of soil saturation. Weaver (1965)
reports that historically, large stands of Spartina pectinata occurred onmnd flats of the Missouri River. Large
stands have been observed south of Denver, now threatened by housing and golf coiu'se developments (Steve
Kettlerpers. comm.).

Vegetation:

GRank & Reasons: G3? (96-02-01).

Comments: Compare this association with Spartina pectinata - Carex spp. Herbaceous Vegetation
(CEGL001477).

Element Distribution
States/Provinces: CO:Sl, MT:S3?, WA:S1, WY:S?

Appendix E -40

Element Sources
Authors: WCS; mod B. L. Heidel.MTNHP Confidencf : 2 IdeiitiTifr: CEGL001476
References: Bourgeron and Engelking 1994, Diiscoll ei al. 1984, Evaus 1989a, Hansen and Hoffman 1988,
Hansen etal. 1989, Hansen et al. 1991, Hansen et al. 1995,Kittel et al. 1996, Weaver 1965

V.A.S.N.k. Seasonally flooded temperate or subpolar grassland
V.A.5.N.K.56. CAREX NEBRASCENSIS SEASONALLY FLOODED HERBACEOUS
ALLIANCE

Carex NEBRASCENSIS Herbaceous Vegetation
Nebraska Sedge Herbaceous Vegetation

Element Concept
Suinmai'y: Tliese minor wetlands occur on the western Gieat Plains and throughout much of tlie western U.S.
Elevation ranges from 1000-2800 m (3300-9200 feet). Stands form open meadows that occur along the margins of
sheanibanks, flat Hoodplains, and lakes often forming a band along the alhivial teirace. Stands have also been
sampled from marshy areas surrounding springs and below seeps on lower hillslopes. This association is often
found on well -developed soil, but occurs on a wide variety of soil types ranging fiom saturated organics to
Mollisols to Entisols. Soils tend to be fine-textured alluvium, ranging from sandy, silly loam, clay loam, or clay to
organic and are typically gleyed and mottled near the surface because of tlie high water table most of the growing
season. Tlie vegetation is characterized by a moderately dense to dense perennial graminoid layer dominated or
codominated by Carex nebrascensis (25-99% cover), that generally forms small- to medium-sized meadows.
Stands often are neariy pure Carex nebrascensis, but a variety of other graminoid species may be present such as
Carex pvaegracilis, Calamagvo^^tis stncta, Deschampsia caespitosn, Eleochans palustris, Glycsha striata, Juncus
balticiis. Schoenoplectus pungens (= Sciipuspiingens), or Tnglochm mantima. Forb cover is generally low, but
can be high in moist locations. Common forbs include Suiybia mtegnfolia (= Aster mtegvifolms) , Geiim
macrophylhim, Mentha arvensis, Mimulus glabratus, and Ranunculus cymbalaria. Introduced species Poa
pratensis, Poa palustvis^ i^ntX Melilotus officinalis m^y also be common.

Envli^onment: This wetland plant association occurs on the western Great Plains and throughout much of the
western U.S. Elevation ranges from 1000-2800 m (3300-9200 feet). Stands form open meadows that occur along
tlie margins of streambanks, flat floodplains, and lakes often forming a band along the alluvial terrace. Stands
have also been sampled from marshy areas surrounding springs and below seeps on lower hillslopes. Tliis
association is often found on weU-developed soil, but occurs on a wide variety of soil types ranging fiom saturated
organics to Mollisols to Entisols. Soils tend io be fme-textiued aUuvium, ranging fiom sandy, silty loam, clay
loam, or clay to organic and are typically gleyed and mottled near the surface because of the high water table most
of the growing season.

Vegetation: Tliese wetlands are characterized by a moderately dense to dense perennial graminoid layer
dominated or codominated by Carex nebrascensis (25-99% cover), that generally forms small- to medium-sized
meadows. Stands often are nearly pure Carex nebrascensis, but a variety of other graminoid species maybe
present such as Carex praegractlis, Calamagrostts stricta, Deschampsia caespitosa, Eleochans palustns, Glyceria
striata, Juncus balticits, Schoenoplectus pungens (= Scirpus pungens), or Tnglochm mantima. Forb cover is
generally low, but can be high in moist locations. Common forbs include Ewybia mtegnfolia (= Aster
integnfolius), Geum macrophyllum, Mentha arvensis, Minndus glabratus, mid Ranunculus cymbalaria. Introduced
species Poapratensts, Poa palustns, ^wdMelilotus officmalis may also be common.

hi Nebraska, common species iwcXvidt Agrostts stolomfera, Carex hystencma, Carex pellita (= Carex lanuginosa),
Eleochans erythropoda, Equisetum ^'p.yJuncus balttcus, Schoenoplectus pungens (= Scirpus pungens), and
Triglochin spp. (Steinauer and Rolfsmeier 2000).

Dynamics: hi Montana, the Carex nebrascensis Community Type is considered a grazing- disclimax. Under
season-long grazing, Carex nebrascensis increases in abundance, replacing fonner dominant species (Hansen et aL
1995). However, under extreme grazing conditions and a resulting diop in the water table, Juncus balticus or Poa
pratensis can eventually replace Carex nebrascensis. In Nevada, sites dominated by Carex nebrascensis are

Appendix E -41

considered the Potential Natural Community (Manning and Padgett 1995), which appears to be the case in
undisturbed stands in Colorado.

GRank & Reasons: G4 (96-02-01). Tliis type is widely distiibuted, but many examples have been heavily grazed
by cattle, lowering tlieir floristic quality.

Comments: hi the Black Hills, classification of stands was problematic due to identification problems with Carex
nebvascensis and Carex aquatica. The two are difficult to distinguish based on available keys and written
descriptions (Maiiiott and Faber-Langendoen 2000).

Element Distribution
Range: This sedge meadow type is widely distributed from the western Great Plains into the western mountains of
tlie United States, ranging from South Dakota and Montana to possibly as far west as Washington, south to
California and east to New Mexico.

States/Provinces: AZ:S2, CA:S3, CO:S3,ID:S3, MT:S4,NE:S2,NM?,NV:SR, OR:S3?, SD:S?, UT:S3?, WA?,
WY:S3

Element Sources
Authors: J. Drake, mod. D. Faber-Langendoen, mod. K.A. Schuiz, WCS Confidence: 1 Identifier:

CEGL001313

Referfuces: Baker 1982b, Bourgeron andEiigelking 1994, Cooper and Cottrell 1990, Driscoll et al. 1984, HaU
1973, Hall and Hansen 1997, Hansen et al. 19SSb, Hansen et al. 1991, Hansen et al. 1995, Jones 1992b, Jones and
Walfordl995,Kitteletal. 1994, Kittel et al. 1996,Kittel et al. 1999, Kovalchik 1987, Manning and Padgett 1995,
Marriott and Faber-Langendoen 2000, Mutz and Queiroz 19S3, Padgett et al. 19SSb, Padgett et al. 19S9, Steinauer
and Rolfsmeier 2000, Youngblood et al. 1985a, Youngblood et al. 1985b

V.A.5.N.K.53. CAREX PELLITA SEASONALLY FLOODED HERBACEOUS
ALLIANCE

Carex PELLITA - Calamagrostis strjcta Herbaceous Vegetation
Woolly Sedge - Western Bluejoint Herbaceous Vegetation

Element Concept
Suinmai'y: This sedge -bluejoint wet meadow is found in the northern tallgrass prairie region and in the
northeastern Gieat Plains. Stands occur on level ground in shallow depressions and other lowlands on poorly
drained sandy, loamy, or silty clay soils. Standing water may be present for a few to several weeks during most
years. Soil pH is circumnential to somewhat alkahne and organic content can be moderately high. The vegetation
of this community provides approximately 100% cover andtlie dominant vegetation is graminoids, typically 0.5-
1 .0 111 tall. Forbs can be common, but shrubs are rarely found in this type. Tlie most abimdant species are
Calamagrostis stncta, Carex pellita (= Cavex lanuginosa), Carex sartu-ellu , Anemone canadensis, Apocynum
cannabinum, Symphyotrichum lanceolatum (= Aster lanceolatus), Eleochans compressa, Junciis balticus, Phalans
arnndinacea. Polygonum amphibmra, ^nd Schoenoplectus americanus (= Scirpus americanits). Carex buxbaiinui
may be common, except in North Dakota.

Envli^onment: This community occurs on level ground in shallow depressions and other lowlands on poorly
drained sandy, loamy, or silty clay soils. Standing water can be present for a few to several weeks a year (Dix and
Sineins 1967, Smeins and Olsen 1970). Soil pH is circumneutral to somewhat alkaline, and organic content can be
moderately high.

Vegetation: Tlie vegetation of this community provides approximately 100% cover, and the dominant vegetation
is graminoids, typically 0.3-1.0 in taU. Forbs can be common; they had 25% relative cover in the stands studied by
Nelson et al. (19S1). shmbs are rarely found in this type. Tlie most abundant species are Calamagrostis striata,
Carex pellita (= Carex lanuginosa), Carex sartwellu , Anemone canadensis, Apocynum cannabinum,
S^Tiiphyotnchum lanceolatum (= Aster lanceolatus), Eleochans compressa, Juncus balticus, Phalans

Appendix E -42

arurtdinacea, Polygonum amphibmni, and Schoenoplectu^ americamis (= Scirpus amencanus). Carex buxbaiimii
can be common, except in North Dakota.

GRank & Reasons: G3G5 (98-06-22).

Comments: Type concept is a little unclear. Simple dominance by Carex lanugmosa (now Carex pellita in
Kartesz 1994) may not be adequate. Hydrologic placement is difficult, ranging from seasonally flooded to
temporarily flooded. This type may simply be a part of Spavtina pectinate - Calamagrostis stvicta - Carsx spp.
Herbaceous Vegetation (CEGL002027) {wet praiiie), or vice versa. See also Carex pelltta Herbaceous Vegetation
(CEGL001S09).

Element Distribution
Range: Tliis sedge-bluejoint wet meadow is found in flie northern tallgrass prairie region and in the northeastern
Gieat Plains, ranging from northern Iowa, western Minnesota, and the Dakotasto parts of the Canadian praiiie
provinces.

States/Provinces: IA:SU, MB:SU, MN:S?, MT:S3?,ND:S?, SD:S?, SK:S?

Element Sources
Anthors: J. Drake, mod. D. Faber-Langendoen, MCS Confidence: 3 Identifier: CEGL002254
Refei^rnces: Dix and Smeins 1967, Kartesz 1994, Nelson et al. 1931, Smeins and Olsen 1970

V.A.5.N.K.61. ELEOCHARIS PALUSTRIS SEASONALLY FLOODED HERBACEOUS
ALLIANCE

ELEOCHARIS PALUSTRIS ^^.^BACYQ^J^ VEGETATION

Marsh Spikerusli Herbaceous Vegetation

Element Concept
Summai'y: This spikerush wet meadow commnnity is fonnd in the central Gieat Plains of the United States and
Canada and in the western United States. Stands occm' in small depressions in intermittent streambeds or
depression ponds that flood early in the season and may diy out by summer. Stands are composed of submersed
and emergent rooted vegetation nnder 1 m tall that is dominated by Eleochari:^ palustns, often in nearly pure
stands. Soils are generally fine-textured.

Envli^onment: Tliis wetland occurs across the central and northwestern Cheat Plains and western United States.
Elevations range fiom near sea level to 3050 m {in Colorado). In eastern Washington and Idaho it occurs in
valleys and canyon bottoms with low-gradient streams, slonglis, and along tlie margins of ponds and lakes
(Kovalchik 1993). Li northwest Nebraska and southwest South Dakota, tliis commnnity occurs in small
depressions in intermittent stieambeds and depression ponds that flood early in the season and dry ont by summer.
Soils are silty clay formed from weathered siltstone and shale (Steinauer and Rolfsmeier 1997). In southwestern
Soutli Dakota, the type occupies depression ponds in prairies (H. Mamolt pers. comm. 1999). hi Utah stands are
described fi'om small playas on floodplain terraces of a large river (Von Loh 2000).

In Colorado this commimity type occurs on the bottom of ephemeral ponds or playas (Baker and Kennedy 1985),
oris associated with small to moderate-sized ponds or the edges of larger lakes and reservoirs (Bunin 1985,
Padgett et al. 1989). The sites are generally only seasonally flooded, but remain moist throughout the year (Bimin
1935, Padgett etal. 1989). Elevations range &om 1525-2750 m (5000-9020 feet).

Tlie soils of Baker and Kennedy's (1985) stands were derived from Quaternary alluvium, with a heavy clay content
and an average pH of 7.8, shglitly alkahne. Tlie soils reported by Padgett et al. (1989) were mineral soils with
flne-loamy to fine particle sizes or organic. Tliey are commonly ponded throughout the growing season and have
developed fi'oni pond siltation. Hansen et al. (1988a) indicate fliat Eleochans palustris is alkahne-tolerant.

Appendix E -43

Vegetation: Tlii^" wetland association is dominated by submersed and emergent rooted vegetation mider 1 m tali
and occurs across tiie uoithwesteru Gheat Plains and western U.S. within a wide elevational range. Tlie species
composition can be quite variable, but this community is easy to recognized by the blight green, nearly pure stands
of Elsocharis palustn^. Vegetation cover can be sparse to dense (10-90%), but Eleocharis paliistris is the
dominant species, and the only species with 100% constancy. Other species, when present, can contribute as much
as 40% cover, but never exceed that of the Eleochans pahistvis cover. Some of this variation is described from
Colorado (Kittel et al. 1999, Baker and Kennedy 1985). Co-occiirring species in low-elevation stands on the
western slope can include Phalans anmdinacea (= Phalaroides anmdinacea), Junciis balticus, Hordenra jubcitum,
Pascopyrum snuthii, Schoenoplectus americanus (= Sctrpu^ amsncanus), Spargcmium angusttfolium ^ species of
Lemna and Potamogeton, as well as the intvodncGd Meli lotus ojftcinalis ^nd Bromits inermis. On the eastern plains
of Colorado co-occumng species caninchide Leersia oiyzoide:^, Schoenoplectus pimgens (= Sarpiis piingens),
Pamcum virgatum, Carex pelltta (= Carex lanuginosa), and Spartina pectinnta. At montane elevations, other
graminoids, such as Carex aquatilis, Carex utncnlata, and Deschampsia caespitosa are present. Forb cover is
typically low, but can be occasionally abimdant (30%) in some stands. Forb species include Pediculans
groenl?indica, Rhodiola integj'ifolia, audCaltha leptosepala.

In stands fiom eastern Washington, associates include Carex iitnculata, Cicuta douglasu, and species oiGlyceria
and Potaniogeton. Li northwestern Nebraska, stands are dominated Eleochans aacnlans and Eleochans palustvis
which commonly cover the bottoms of the pools and emerge above the water as the pools diy out. Ephemeral
submersed aquatics, such as Callitriche palustris (= Callitnche verna), Potamogeton diversifohus ?indMarsilea
vestita, may be present. As the pools dry out in mid-summer, ephemeral annual forbs, such as Limosella aquatica
and Plagiobothrys scoulen^ may appear. By late ^uwhwgx Amavanthus cahforniciis and Gnaphalmm palustre may
dominate in the lowest parts of the depression (Steinauer and Rolf smeier 1997). In southwestern South Dakota,
vegetation is composed of nearly homogeneous stands of Eleochans palustns . Other emergents, such as
Polygomim amphibmm. Mavsdea vesttta^ and Eleochans ovata^ are occasionally found. Herbaceous cover is
greater than 75% except in areas of deeper open water where floating and submerged aquatic plants occur,
including Bacopa rotundifoha and Heteranthera hmosa (H. Maiiiott pers. comm. 1999). In lower elevation Utah
stands Glaux manttma, Distichlis spicata^ ^wdJuncits balticus were important associates (Brotherson and Barnes
1984).

Few stand data are available for Colorado examples. Generally, it appears that this community is dominated by
Eleochans palustns, forming a scattered to dense overstory, often with few associated species. Commonly
associated graminoids include Hordeum jubatum ?[nd Pascopyrum smtthii. Forbs present m^y iaclude At nplex
argentsa. Polygonum aviculare, ^nd Ronppa sinuata (Baker and Kennedy 1985). Tlie higher elevation stands may
include a slightly different suite of species, but no stand data are available. Ramaley (1942) described a Distichlis
spFffifn- dominated salt meadow on a lakeshore in the San Luis Valley which was ringed by Eleochans palustns.
Communities in Utah include Eleochans acicularis 3nd Alopecuius aequalis as likely associates (Padgett et al.
1989).

Dynamics: Tlie hydrological regime is critically important to this association. Most stands are seasonally to
permanently flooded, although some in the Great Plains occur under intermittenfly to temporarily flooded
conditions.

Baker and Kennedy (1985) suggest that domestic livestock grazing may tend to result in increases in Hordeum
jubatum, Bassia scoparicty and Polygonum aviculare. However, Hansen et al. (1988a) suggest that palatability of
Eleochans palustns is low for both domestic and wild animals, but that heavy grazing may increase this
rhizomatous species and spread it onto adjacent sites. Trampling damage may occur to this type when animals
heavily use the sites supporting it, particularly during drought years (Hansen et al. 1988a). Water level fluctuations
over a year of greater than 1 m will not support this type (Hansen et al. 19SSa).

GRank & Reasons: 05(96-02-01).

Element Distribution
Range: Tliis spikerush wet meadow community is found in the cential Great Plains of the United States and
Canada and in the western United States.

Appendix E -44

States/Provinces: CA?, CO:S4, ID:S3, MT:S5,NE:S?, NY:SR, OR:S5, SD:S?, SK:S?, UT:S3?, WA:S?, WY:S3

Element Sources
Authors: D. Fabei-Langeudoen, mod. K. Schulz, mod. M.S. Reid, WCS Confidence: 1 Identifier:

CEGL001833

References: Baker 1983c, Baker and Kennedy 1985, Billings 1945, Bourgeron andEngelking 1994, Brotherson
andBarnes 1984, Bunin 1985, Driscoll e( al. 1984, Ellis et al. 1979, Flowers 1962, Hall and Hansen 1997, Hansen
etal. 1988a, Hansen et al. 19SSb, Hansen et al. 1991, Hansen et al. 1995,Kettler andMcMullen 1996,Kittel and
Lederer 1993,Kittel etal. 1994, Kittel et al. 1999, Kovalcliik 1987, Kovalchik 1993, Mntel 1973, Mutel andMaiT
1973, Padgett et al. 1988b, Padgett et al. 1989, Penfound 1953, Ranialey 1919a, Ranialey 1942, St earns -Roger Inc.
1978, Steinauer and Rolfsnieier 2000, Stewart 1940, Von Loli 2000, Yonngblood et al. 1985a

V.A.5.N.K.13. JUNCUS BALTICUS SEASONALLY FLOODED HERBACEOUS
ALLIANCE

JUNCUS BALTICUS HERBACEOTJS VEGETATION

Baltic Rush Herbaceous Vegetation

Element Concept
Suinmai'y: This Baltic rush wet meadow community is found widely thronghont the western United States. This
wet meadow vegetation occurs as small, dense patches on flat stream benches, along overflow channels, and near
springs. Soils are usually sandy clay loam or fine sands and mottled or gleyed. Stands are characterized by a
dense sward of Jiinciis balticns and often minor cover ofCavex species, including Carex aquattlts, Carex
praegiQcilis, Carex nebrascensis, or Carex utriculata. Other common species include Deschampsia caespitosa,
Dtstichlts spicata, Gfycsna striata, Hordeiim jiibatum, Muhlenbevgia aspenfolta, Phleum alpimim^ ^nd Spo rob olu^
aivotdes. The introduced perennial sod grasses Poa praten:^ts oiAgvo^^ti:^ stolomfera codominate some stands.
Forb cover is generally low and includes wetland species like Caltha leptosepala and Dodecatheon pnlchellum.
Shmbs are not common. This association is often considered to be a grazing-induced community since it increases
with disturbance.

Envii'onment: Tliis widespread herbaceous wetland community is ft)und throughout western North America.
Elevation ranges fiom 1420-3500 m. Stands usually occur as small, dense patches on flat to gently sloping sites
near seeps and stieams. Stream channels are highly variable in size and type ranging ftom narrow to moderately
wide, and deeply entienched to very sinuous (Kittel et al. 1999). Soils are also variable and range ftom alluvial
sandy and well-drained, to poorly drained silty clay loam, to organic; however, soils tend to be finer-textured,
alkahne and may be sahne (Brotherson and Barnes 1984, Kittel et al. 1999, Padgett et al. 19S9). Cobbles and
gravel are common on many sites, and gleyed and mottled horizons are often present because of ftooding or higli
water tables (Kittel et al. 1999).

Vegetation: This association is characterized by a low (<50 cm), dense graminoid layer dominated by the
rhizomatous perennial Junciis balticns. Minor cover of Carex species, including Carex aquatilis, Carex
praegracilis, Carex nebrascensts or Carex utriculata^ is often present. Other common graminoids include
Deschampsia caespttosa, Disttchhs spicata, Glyceria striata, Hordeum jubatum, Muhlenbergta aspenfolta,
Phleum alpinum^ and ^orobolus airoides. Forb cover is generally low but may include Caltha leptosepala^ Glaux
mantinia, Maianthemum stellatimi, ^nd Dodecatheon pidchellum. Shrubs are not common, but occasional Salix
spp. may occur. Some stands may be codominated by the introduced perennial sod grasses Poa pratensis or
Agrostis stolomfera. Other introduced species, such as Taraxacum officinale, Tnfoliurrt spp., Cirsium arvense,
Lactuca serriola, Phleum pratense, and Thinopyrum intermedium, may occur in disturbed stands.

Dynamics: Tliis association is considered by some to be a grazing-induced community because Jurtcus balticus is
tolerant of grazing (low palalability when mature) and increases with grazing disturbance (Hansen et al. 1995,
Padgett el al. 1989). Nearly pure stands of Jurtcus balticus may indicate that the site was heavily grazed in the past
(Hansen et al. 1995). However, this association also occms as a stable, late-seral commimity in areas with low
disturbance (Kittel and Lederer 1993).

Appendix E -45

GRank & Reasons: G5 (96-02-01).

Comments: Tliis association is often con^dered to be a grazing-induced community since it increases with
grazing distiubance.

Element Distribution
Range: Tliis Baltic rush wet meadow community is found widely throughout the western United States, ranging
fi'om Sonth Dakota and Montana west to Wasliington, sonth to possibly California, and east to New Mexico.

States/Provinces: CA?, CO:S5, ID:S5, MT:S5,NM:S4,NV:S?, OR:S5, SD:S?, UT:S3S4, WA:S3S4, WY:S3

Element Sources
Anthers: J. Drake, mod D. Faber-Langendoen, mod. K. Schulz, WCS Confidence: 1 Idrntifier:

CEGLO0i33S

Refei'fnces: Baker 1984a, Bourgeron andEngelking 1994, Brotherson and Barnes 19S4, Bunin 1985, Driscoll et
al. 1984, Faber-Langendoen 2001, Flowers 1962, Hall and Hansen 1997, Hansen et al. 1988b, Hansen et al. 1991,
Hansen etal. 1995, Hess 1981, Johnston 1987, Jones and Walford 1995, Kartesz 1994, Kittel andLederer 1993,
Kittel et al. 1994, Kittel et al. 1999, Komarkova 1986, Manning 1988, Mulda\in et al. 2000a, Mutel 1973, Mutz
andGiaham 1982, Olson and Gerhart 1982, Padgett 1982, Padgett etal. 1989, Rector 1979, Richard et al. 1996,
Shupe etal. 1986, Stewart 1940, Tliompson 2001, Tiihy and Jensen 1982, Von Loh 2000, Wasser and Hess 1982,
Youngbloodetal. 1985a

V.A.5.N.K.20. PHALARIS ARUNDINACEA SEASONALLY FLOODED
HERBACEOUS ALLIANCE

PHALARIS ARUNDINACEA WESTERN HERBACEOUS VEGETATION

Reed Canaiy Grass Western Herbaceons Vegetation

Element Concept
Summai'y: This association is reported £om througliont Montana, Idaho, northeastern Utah, and the Columbia
Basin of Washington, bntishkely more widespread in tlie western United States. Its distribution as a natiual type
is complicated becanse this native species is widely cultivated as a forage crop and has escaped and estabhshed in
wetlands and riparian areas, displacing the local flora. Elevations range fiom near sea level to 1700 m. Stands are
found along riparian areas, pond and lake margins, wet meadows, and intermittent drainages. Soils are commonly
flne-textured and may be flooded for brief to extended periods. Tlie vegetation is characterized by a dense, tall
herbaceous layer (often >S0% canopy cover andl.5-2 m tall) that is dominated by Phalans anindinacea^^XuQh
tends to occur in monocultures. Associated species may include Equisetum a^yense, Muhlenbergia asperifolia,
Mentha arvensis, Schoenoplectus acutiis (= Scirpns acutus), and many other species in trace amounts where
disturbed. Introduced species such as Leptdium latifolium, Cirsium ar\;ense, Sonchns oleracens, Enphovbia esula,
and Phleur\i pratense are common in some stands.

Environment: This association is reported from tliroughout Montana, Idaho, Washington and noitheastem Utah,
bntis likely more widespread in the western United States. Elevations range fiom near sea level to 1700 m.
Stands are found along riparian areas, pond and lake margins, wet meadows, and intermittent drainages. Sites are
flat to rolling. Soils are commonly fine-textured, but can be coarser in texture. Subsoil is often mottled and gleyed
(Crawford 2001). Sites are generally fiooded during the growing season, but flooding can vary fi-om brief to
extended periods.

Vegetation: Tliis association is characterized by a dense, tall herbaceous layer (often >90% canopy cover and 1.5-
2 m tall) that is dominated by Phalans arundmacea^ which tends to occur in monocultures. Associated species
such as Equisetum aiyen^^e, Muhlenbergia asperifoha, Mentha arvensis. Schoenoplectus acutus (= Scirpiis acutiis).
Polygonum amphibmm. Solidago canadensis, Uvtica dioica, and many other species may be present in trace
amounts especially where disturbed. Occasional Populiis tremuloides, Salix exigua, Rubus tdaeus^ or
SyniphoncGipos albus may be present is some stands. Introduced species such as Lepidmn} latifoluim, Cwsium
arvense, Sonchus oleraceus. Euphorbia esula, Poa pratensis^ and Phleum pratense are common in some disturbed

Appendix E-4<j

stands.

Dynamics: Phalavis anindinacea produces abundant herbage audis planted for livestock forage. It is tolerant of
moderate grazing by livestock, altliough heavy grazing will reduce density (Hansen et al. 1995). Phaiaris
anmdinacea is a threat to riparian and wetland areas because it spreads rapidly from rhizomes ^dominating the
sites, and is extiemely difficult to remove once established (Hansen et al. 1995). Fire lias been used with limited
success to contiol the spread of Phalans arundmacea^ but the high water table where it grows makes it difficult to
bum during the growing season (Hansen et al. 1995) .

Van Loh (2000) found stands growing on seleniimi-rich sites. It is not known if selenium is translocated into the
plant tissue.

GRank & Reasons: G5 (99-03-03).

Comments: Other natural associations included in this aUiance are found throughout the northeastern United
States, but this western association's distribution as a natural type is not clear because of extensive planting as a
forage crop (Hansen et al. 1995, Hall and Hansen 1997). Further work is required to resolve the natural versus
introduced nature of this type in western North America.

Element Distribution
Range: This association is reported from throughout Montana and Idaho and into northeastern Utah and is likely
more widespread in the western United States. Its distiibution as a natural type is complicated because tins native
species is widely cultivated as a forage crop and has escaped and established in many wetlands and riparian areas.

States/Provinces: ID:S4?, MT:S4,NM:S4?, UT:S?

Element Sources
Authors: K. Schulz, WCS Confidencf: 1 Identifiei: CEGL001474

Referfuces: Bourgeron andEngelking 1994, Cooper et al. 1995, Crawford 2001, Driscoll et al. 19S4, Hall and
Hansen 1997, Hansen et al. 1995, Muldavin et al. 2000a, Von Loh 2000

VA.5.N.L Semipermanently flooded temperate or subpolar grassland

V.A.5.N.L.6. SCHOENOPLECTUS PUNGENS SEMIPERMANENTLY FLOODED
HERBACEOUS ALLIANCE

SCHOENOPLECTUS PUNGENS HERBACEOUS VEGETATION

Tlneesquare Herbaceous Vegetation

Element Concept
Suinmai'y: This bulnisli wet meadow community is found in the western United States in the intermonntain
basins, as well as in western parts of tlie Gieat Plains. Stands are found along low-gradient, meandering, usually
perennial streams and around tlie margins of ponds and marshes. Schoenoplectus pungens (= Sarpus pungens)
dominates the dense, 0.3- to 0.6-m tall herbaceous vegetation layer. Other species tliat often are present include
Schoenoplectus mantimus (= Sarpus manttmus), Spajtuia gractlts, Hordeum jubatum, Pascopyrum snuthu^
Juncus balticus, Eleochans palustris, Lemna minor, Sagittaria latifolia, and Typha spp. Stands of this association
contain no tree or shrub layer, but a few scattered trees and shrubs may be present, most commonly Populus
deltoides, Salix aniygdalades, Salix exigua. S\-raphoricarpos occidentalism or Sarcobatus vermiculatus. Substrates
are generally dark, organic, fine-textiwed soils derived fi'om alluvium.

Envli^onment: Stands of tliis widespread association are fonnd throughout much of tlie western U.S. in
appropriate wetland habitat. Elevations range fiom 1000-2400 m. Stands occur along low-gradient, meandering,
usually perennial streams, aronnd the margins of ponds and marshes, in low-lying swales, and abandoned or
overflow channels where tlie soils remain saturated (Hansen et al. 1995, Kittel et al. 1999, Jones and Walford
1995, Walford 1996). It also occurs on silt and sandbars witliin the active channel. Soils are generally derived
fiom alhivium and are fine-textured, black, alkaline, organic anoxic with gleying. Soils range fiom normal to
saline with pH ranging fiom 7.4-9.1.

Appendix E -47

Vegetation: Tliis widespread wetland association is characterized by a dense, 0.3- to 0.6-ni tall herbaceous
vegetation layer that is domm?ited by Schoenoplsctu^ pungent (= Scirpus pungens). Associated species include

Schoenoplectiis maritinuis {= Scirpris manttmus), ^artina gractlts, Hordeum jubatum, Pascopyrum smithu,
Juncus balticus, Elsochans palustris, Lemna minor, Sagittaria latifolia, and Typha spp. Stands of this association
contain no tree or shrub layer, but a few scattered trees and shrubs may be present, most commonly Popidus
deltoides, Salix amygdalades. Salix extgua. S\-mphoncarpos occidentalism or Sarcobatus vermiculatus.

Dynamics: Stands of this association are flooded in tlie spring (Larson 1993).

GRank & Reasons: G3G4 (9S-04-09).

Comments: Muldavin et al. (2000a) described 5 Sc hoc noplectus pungens (= Scirpus pungens) community types
fi'om New Mexico. Most are co dominated with an associated species listed in the vegetation description, e.g.,

Eleochans palustns, Distichlis spicata, Paspalum distichura , and Equisehim laevigahini , with one being a
Schoenoplectiis pungens Monotype Community Type reported fiom the Gila River basin. Muldavin et al.'s
(2000a) concept of this commiuiity type stales that it can be dimim^Xtdhy Schoenoplectus pungens (= Scirpus
pungens) or Schoenoplectus americanus (= Sarpus amencanus. = Scirpus olneyi). Hansen et al. (1995) also
include Schoenoplectus amencanus in their Scirpus pungens Habitat Type. Tliis association needs furtlier review
to clarify whether to include stands where Schoenoplectus pungens is not the dominant species.

Element Distribution
Range: Tliis community is found in the western United States in the intermountain basins, as well as in western
parts of the Great Plains, fi'om Montana south to Colorado, and west into Nevada, Utah, and Wyoming.

States/Provinces: CO:S3, KS:S?, MT:S3,ND:S?, NM:S?,NV:S?, SD:S?,UT:S2S4, WY:S?

Element Sources
Authors: G.P. Jones, mod. K Schnlz, WCS Confidence: 2 Identifier: CEGL001587

References: Bourgeron andEngelking 1994, Brotherson and Barnes 1984, Bundy et al. 1996, Driscoll et al. 1984,
Gleason and Cronquist 1991, Great Plains Flora Association 1986, Hansen et al. 1991, Hansen et al. 1995, Jones
andWalford 1995, Kittel and Lederer 1993, Kitteletal. 1994, Kittel et al. 1999, Larson 1993, Lauver et al. 1999,
MTNHP 1988, Muldavin et al. 2000a, Walford 1996

V,A.7.N,e, Medium -tall temperate or subpolar grassland with a sparse
needle-leaved or microphyllous evergreen shrub layer

V.A.7.N.E.11. ARTEMISIA CANA SHRUB HERBACEOUS ALLIANCE

Artemisia cana ssp. cana / Pascopyrum smithh Shrub Herbaceous Vegetation
Silver Sagebrush / Western Wheatgra^'s Shrub Herbaceous Vegetation

Element Concept
Summai'y: This association has been described from the Great Plains of central and eastern Montana, far western
Nortli Dakota, northwestern Soutli Dakota, and northeastern Wyoming. It occupies terraces and floodplains along
stieanis, where alluvium contains more soil water tlian is available in the uplands. Artenusta cana ssp. cana
dominates the shrub layer, which may also inchide small amounts of Symphoncarpos occidentahs, Sarcobatus
vermiculatus, or Chrysothamnus sp. The undergrowth typically is dense and composed mainly of graminoids, with
forbs contiibuting little cover. Pascopyrum snuthn often dominates, and in many stands several otlier species may
codominate, especially M^s^e/^fl virtdula, Poa pratensis, aud Bromus japonicus (or another exotic, annual brome
grass). Exotic grasses (Poa pratensis, Bromus japonicus) dominate the imdergrowth in many stands. Bouteloua
gi'acilis and Carex fihfoha , both more typically upland species, may contribute substantial cover. Common forbs
are Taraxacum spp. (exotic), ^c^f/^sg millefolium, Artemisia ludoviciana^ and Vicia amencana.

Environment: Tliis community is found on flat to gently sloping alluvial terraces and fans near larger creeks and
rivers. Thilenius et al. (1995) foimd tliat most stands were raised at least 1 m above the general floodplain. Soils
are formed from alluvium and are medium- to fine-textured. Flooding may occur frequently.

Appendix E-4S

Vegetarton: Tliis community is dominated by moderately dense to dense graminoids less than 1 m tall.

Pascopyrum sraithu is usually the most abundant among these. Poa pratensi^, Bouteloua gracilis, ^nd Nas^ella
viridula are also common. Calamovilfa longifoha. Hesperoshpa comata (= Stipa comata), and Achnatherum
hymenotdes (= Oryzopsis hymenoides) are sometimes present. Short shrubs, especially -4?te^^j^Q cana and
sometimes Symphoricarpos occidentalism have 10-2_^% cover. Forbs and nonvascular species are generally rare.

GRank & Reasons: G4 (00-11-29). Tliis association seems to be common witliin a large geographic range,
occiuring fiom nortliern Montana as far south as central Wyoming, and fioni central Montana as far east as west-
cential South Dakota. It is restricted to mesic swales, terraces andfloodplains along streams of nearly any size,
where soils are deep and have low to moderate amounts of salts. However, the presence of exotic species Poa
pvatensis and Bromns japomciis (or other annual brome grasses) in many of tlie stands is cause for concern. The
global rank has been changed £om G3? to G4. Prolonged, heavy grazing by livestock may pose a threat to this
association by favoring the grazing -tolerant exotic species.

Comments: Tliis association undoubtedly exists, but the amount of variation in species composition and
vegetation structure, and the geographic range, must be better documented. It is unclear whether stands in which
Nassella vindula or Elymus lanceolatus ssp. lanceolatus dominate or codominate the undergrowtli should be
included in this association or placed into different associations. For the Pascopyrum smithti - Nassella vindula
Herbaceous Vegetation (CEGL001583), eitlier Pascopyi-ur.i smithii or Elymus lanceolatus ssp. lanceolatus may
dominate.

Tliis community appears to be veiy closely related to Artemisia cana /Pascopyrum smithii Shnibland
(CEGL001072) which is found in Montana, western North Dakota, and western South Dakota. The most apparent
difference is the cover of shrubs. Further comparison may result in the combination of these two types.

Element Distribution
Range: Tliis association is known to occur fi^om northern Montana as far south as central Wyoming, and :&om
cential Montana as far east as west-cential South Dakota.

States/Provinces: MT:S?,ND:S?, SD:S?,WY:S3?

Element Sources
Authors: J. Drake, WCS Confidence: 1 Identifier: CEGL001556

Refei'fuces: Bourgeron andEngelking 1994, DeVelice et al. 1991, Driscoll et al. 19S4, Hansen and Hoffman
19SS, Hansen et al. 1984, Hansen et al. 1995, Jones and Walford 1995, Tliilenius et al. 1995

V,A.7.N,g. Medium-tall temperate or subpolar grassland with a sparse cold-
deciduous shrub layer

V.A.7.N.G.5. RHUS TRILOBATA SHRUB HERBACEOUS ALLIANCE

Rhus trh^obata / Pseudoeoegneeia spicata Sheub Heebaceous Vegetation
Hl-scented Smnac / Bluebmich Wheatgiass Shnib Herbaceous Vegetation

Element Concept
Summai'y: This shrub prairie type is found in the United States on diy mid to upper slopes andridgetops in the
eastern plains and mountains of Wyoming and Montana. Slope and aspect are variable, but soils are consistently
shallow and rocky. Herbaceous species dominate the vegetation with short shnibs and nonvascular plants present
but of lesser impoitance. Total vegetation cover is moderate, and few plants grow taUer than 1 m. Shmbs
generally have from 10-25% cover. Rhus trilobata is tlie most common. It is often found ^it\\ Artemisia frigida,
Artemisia tridentata, Prunus vtvgmiana, Ribes cereum, or Eviogonum spp. Pseudoroegneria spicata is the most
abimdant herbaceous species. Others commonly found include Floeleria macrantha, Schtzachyrium scopanum,
Bouteloua curtipendula, Bvomus tectorum^ and Opuntiapolyacantha.

Appendix E -49

Envii^oninent: Tliis community is typically found on dry mid to upper slopes and ridgetops. It lias been identified
on butte tops in eastern Wyoming (Tliileniiis et al. 199_^). Slope and aspect are variable, but soils are consistently
shallow aud rocky. Tliey often form fiom sandstone parent materials, aud rock fiagmeuts, outcrops, and bare soil
cover much of the ground (Mueggler aud Stewart 1978).

Vegetarton: Herbaceous species dominate the vegetation with short shrubs and nonvascular plants present but of
lesser importance. Total vegetation cover is moderate (Brown 1971, Thilenius et al. 1995) and few plants grow
taller than 1 m. Shrubs generally have fiom 10-25% cover. Rhus tnlobata is tlie most common. It is often found

^\i\\ Artemtsict fngida, Artemisia tridentata, Prunus virgmiana, Ribes csveum^ or Enogonum spp.
Pseudovoegneria spicata is the most abundant herbaceous species. Others commonly found include Koelena
macrantha, Schizachynum ^copanum, Bouteloua cmttpendiila, Bromus tectoruni, and Opnntta polyacantha.

GRank & Reasons: 04(96-02-01).

Element Distribution
Range: Tliis shrub prairie type is found in the United States on diy mid to upper slopes and ridgetops in the
eastern plains and mountains of Wyoming and Montana.

States/Provinces: MT:S4, WY:S2S3

Element Sources
Authors: J. Drake, WCS Confidence: 1 Identifier: CEGL001120

References: Bighorn Coal Mine n.d., Bonrgeron andEngelking 1994, Brown 1971, Driscoll et al. 1984, Hansen
andHoffinan 1988, Mneggler and Stewart 1980, Tliilenius et al. 1995, Tweit and Houston 1980

V,A.7.N.n, Intermittently flooded temperate or subpolar grassland with a
sparse xeromorphic (evergreen and/or deciduous) shrub layer

V.A.7.N.N.I. SARCOBATUS VERMICULATUS INTERMITTENTLY FLOODED
SHRUB HERBACEOUS ALLIANCE

SARCOBATUS VERMICULATUS / PASCOPYRUM SMTTHH - (ELYMUS LANCEOLATUS) SHRUB

Herbaceous Vegetation

Black Greasewood / Western Wlieatgrass - (Stream side Wild Rye) Shnib Herbaceous Vegetation

Element Concept
Summai'y: This greasewood siiiiib prairie is foiiud in saline habitats in (he nortliwestem Gieat Plains of the
United States and Canada. Stands occur on flat to geuHy sloping alluvial fans, terraces, lakebeds, and floodplains.
Tlie soil is usually deep clay, silty clay, sandy clay, or loam, although coarse soils are possible. Tliey are saline or
alkahne, but salt crusts on the siifface are typically absent. Parent material is usually alluvium. Tliis community
has moderate to dense vegetation cover. Medium-tall {0.5-1.5 m) shnibs are scattered throughout with a total
shrub canopy of 10-25%. The shnib layer is doim\i?iitdhy Save obatiis vermtculatus y\^iih Artemuta tndentata.
Atnplex confertifolia, and Chrysothamnus viscidiflorus in smaller amounts. Symphoricarpos occidentahs and
Rhus aromatica are sometimes found in more mesic microhabitats within this community. Herbaceous cover is
sparse beneath the shrubs and othei"wise moderate to dense. Tlie dominant species are typically 0.5-1 m tall. Tlie
most abundant species is Pascopyvum smithu, usually accompanied by Bouteloua gracilis. Bvomus japomcus ,
Bromus tectorum, and Hesperosttpa comata {= Stipa comata). Few forbs are found in this community, ^c^f/^eo
millefolium and Opuntta polyacantha are the only species with high constancy. Overall species diversity in this
commimity is low.

Envii^onment: This community is found on flat to gently sloping alluvial fans, terraces, lakebeds, and floodplains
(Mueggler and Stewart 1978, Hansen andHoffinan 19SS). Dodd and Coupland (1966) found Sarcobatus
yevniiculatus in association with Pascopyvum smithn only on tlie most arid parts of southwestern Saskatchewan.
The soil is usually deep clay, silty clay, sandy clay, or loam (Hirsch 19S5, Jones andWalford 1995), although
coarse soils are possible (USFS 1992, Thilenius et al. 1995). They are saline or alkaline, but salt crusts on the

Appendix E-50

surface are absent {Tliileiiius et al. 1995, but see Steinauer andRolf^ineier 2000). Parent material is usually
alluvium. Flooding during the spring is possible.

Vf gftation: Tliis community lias moderate to dense vegetation cover (Joues and Walford 1995, Tliileuius et al.
1995). Medium-tall (0.5-1.5 m) shrubs are scattered throughout, with a total shrub canopy of 10-25% (Hansen and
HofQnan 19SS, USFS 1992). Tlie shnib layer is domiualed by Sarcobatus verraicidatiis^ v/i^Atnplex

confevtifoliQ. Atnplex cane^cens, Atnplex argentea, Artemi^^ict tndentata, and Chrysothamniis viscidiflonis in
smaller amounts. Symphoncarpos occidentahs and Rhus ai'omahca are sometimes found in more mesic
microhabitats witliin this community (Hirsch 19S5). Herbaceous cover is sparse beneath the shrubs aud moderate
to dense in between. Tlie dominant species are typically 0.5-1 m tall. Tlie most abundant species is Pascopyrum
smithu^ usually accompanied by Bouteloua gracilis. Bvomns japomcus, Bromiis tectorum, and Hesperostipa
comata (= Stipa coniata). Fewforbs are found in this community. Achillea millefolium and Opuntta polyacantha
are the only species with high constancy. Otlier species present may inchide Gnndelta squairosa. Overall species
diversity in this community is low (Hansen and Hoffinan 1988, Von Loh et al. 1999). In Nebraska, shrub species
cover may be very low, and saline pockets may contain Distichlis spicata and Sporobolus aivoides. Astragalus
bisidcatiis may be prominent (Steinauer and Rolfsmeier 2000).

GRank & Reasons: 04(96-02-01).

Comments: Compare this association with Sarcobatus vei'miculatus / Elymus elymoides - Pascopyrum smithu
Shrubland {CEGL001365) from New Mexico.

See Steinauer and Rolfsmeier (2000) for a description of the stands in Nebraska. Sarcobatus vermiculatiis /
Distichlis spicata - (Puccmellia nuttalliana) Shmb Herbaceous Vegetation (CEGL002146) may be a more sahne
version of this type.

Element Distribution
Range: Tliis greasewood shrub prairie is found in saline habitats in the northwestern Great Plains of the United
States and Canada, ranging from northwestern Nebraska north to the Dakotas and Saskatchewan.

Statfs/Provinces: MT:S4,ND:S4?, NE:S2, SD:SU, SK?, WY:S4

Element Sources
Authors: J. Drake, WCS Confidencf: 1 Identifier: CEGL001508

References: Bourgeron andEngelking 1994, Brown 1971, Dodd and Couplandl966, Driscoll et al. 1984, Eartli
Resource Technology n.d., Fisser et al. 1965, Hamner 1964, Hansen and Hoffman 1988, Hansen et al. 1984, Hirsch
19S5, Johnston 1987, Jones and Walford 1995, MTNHP 1988, Mueggler and Stewart 19S0, Olson and Gerhait
19S2, Steinauer and Rolfsmeier 2000, Tliilenius et al. 1995, USFS 1992, Yon Loh et al. 1999

Appendix E -51

VIL SPARSE VEGETATION

VII.C.4.N.a. Soil slumps or landslides

VII.C.4.N.A.400. ERIOGONUM PAUCIFLORUM SPARSE VEGETATION
ALLIANCE

ERIOGONUM PAUCIFLORUM - GUTIERREZIA SAROTHRAE BADLANDS SPARSE VEGETATION

Small-flower Wild Buckwheat - Snakeweed Badlands Sparse Vegetation

Element Concept
Suinmai'y: Tliis badlands type is found in Hie northwestern Great Plains, in badlands topography. Li Badlands
National Park, Soutli Dakota, stands occur on eroded formations of Cretaceous Pierre shale, Oligocene Brule
siltstone and Chadron clayey mudstone and shale, and Miocene Arickaree sandstone. Brule formation siltstone is
often capped by Rocky Ford volcanic ash and may also contain veins of chalcedony. Soils are undeveloped, poor,
loose, and easily eroded. The topography is typically flat, and stands occur on erosional outwash fans.
Structurally, stands rarely exceed 10% vegetative cover and is often less than 5%. On level terrain, tlie vegetation
is relatively evenly distributed, but on steeper slopes and cliffs the vegetation may grow in patches and in rows or
seams. In Badlands National Park, plant species that are nearly always present include the dwarf-shnibs
Ehogomim pauciflovum, Gutierrezta savothrae, Opuntia polyacantha, Atnplex argentea. Cryptantha thyrsiflova,
and the forb Grindelia squarrosa. Atnplex canescens dwarf-shrubs were observed throiigliout the type, but were
typically short -statured and scattered in distribution.

Envli^onment: In Badlands National Park, South Dakota, tliis type is typically found on silty/sandy outwash fans
newly deposited by eroding badlands formations. These formations include Cretaceous Pierre shale, Ohgocene
Bnile siltstone and Chadion clayey mudstone and shale, and Miocene Aiickaree sandstone. Soils are undeveloped^
poor, loose, and easily eroded. Tlie topogiaphy is typically flat, and stands occur on erosional outwash fans. One
stand, comprised of four-wing saltbush, occupies a large badlands flat and erosion fan (VonLoh et al. 1999).

Vegetation: Tliis badlands community type rarely exceeds 10% vegetative cover and is often less than 5%. On
level terrain, the vegetation is relatively evenly distributed, but on steeper slopes and cliffs the vegetation may
grow in patches and in rows or seams. In Badlands National Park, plant species that are nearly always present
include the dwarf-shnibs Enogonum pauciflovum, Gutiervezta savothrae, Opuntia polyacantha, Atnplex avgentea,
and Cryptantha thyi'^tflora, and the forb Gvmdelia squavrosa. Atriplex canescens dwarf-shnibs were obsei"ved
tliroughout the type, but were typically short -statured and scattered in distiibution {Von Loh et al. 1999).

GRank & Reasons: G4G5 (00-01-31). In Badlands National Park, Soutli Dakota, this community type occupies
badlandfonnalions, which cover approximately 45% of the park (Von Loh et al. 1999). It is probably found in
other badlands habitats in the Northern Gieat Plains.

Higli-rankrd ^rcies: In Montana, much of the \\2ibit9X fot Astragalus barrit falls within this association.

Element Distribution
Range: Tliis badlands type is found in the nortliwestern Great Plains in badlands topography or on azonal soils in
other than badlands-dominated landscapes.

States/Provinces: MT?, ND:S?, SD:S?

Element Sources
Authors: D. Faber-Langendoen, MCS; mod. B. L. Heidel, MTNHP Confidence: 3 IdentUier: CEGL005270
Refei'fnces: Von Loh et al. 1999

Appendix E -5 2

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Appendix E -5 3

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Appendix E-54

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Appendix E -5 5

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AppendixE-_^6

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Appendix E -5 7

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Keammerer, W. R. 1987. Bentonite regional vegetation study. Prepared for Crook County Bentonite Producers
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Appendix E-59

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Marr, J. W., and D. L. Biickner. 1974. Colorado to Wyoming pipeline corridor study. Unpublished report for

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Mine Reclamation Consailtants. 1977. Buckskin Mine Apphcation No. 500-T2. On file at Wyoming Department
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Appendix E -60

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MTNHP [Montana Natural Heritage Program]. 1988. Draft guide to the natural vegetation of Montana. Montana
Natural Heritage Program, Heleua. 389 pp.

MTNHP [Montana Natural Heritage Program]. No date. Unpublished data on file. Heleua, MT.

Miieggler, W. F., audW. L. Stewart. 1980. Giasslaud and shrublaud habitat types of western Montana. USD A
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Mutel, C, and J. W. Marr. 1973. A vegetative study of three montane herbaceous basins. Journal of tlie
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Mutz, K. M., and J. Queiroz. 1983. Riparian community classification for the Centennial Mountains and South
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Mutz, K. M., and R. Giaham. 1982. Ripaiian community type classification -Big Piney Range Distiict, Wyoming.
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NatureServe. 2002. International Classification of Ecological Communities: Terrestrial Vegetation. Natural Heri-
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Nelson, W. T, W. T. Barker, andH. Goetz. 1981. Habitat type classification of grasslands of Sheyenne National
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Ode, Dave. Personal communication. South Dakota Natinal Heritage Program, Pierre, SD.

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Appendix E -61

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Appendix E -62

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Strong, L. L. 1980. Estimating phytomass production of habitat types on sagebnisli steppe. Unpublished thesis.
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Sweetwater Uraniimi Project. 1978. Application No. 481. On file at Wyoming Department of Environmental
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Taylor, J. E. and T. L. Hoist. 1976. Grass and shrub plant community classification. USES Contiact Research
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Tliilenius, J. F. 1972. Classification of the deer habitat in the ponderosa pine forest of the Black Hills, South
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Appendix E -63

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Appendix E-_^S

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Appendix E -64