. ,■>:. uii;

Vegetation of the

Yellow Water Triangle,

Montana

2009

MONTANA STATE LIBRARY

S 574.9786 F2v C.2 Jorgensen
Vegetation ot the Yellow Water Triangle

3 0864 00028713 9

Vegetation of the

Yellow Water Triangle,

Montana

by

Henry E. Jorgensen
(photos by the author)

Wildlife Division
MONTANA DEPARTMENT OF FISH AND CAME

in cooperation with

Bureau of Land Management

UNITED STATES DEPARTMENT OF THE INTERIOR

1979

Permission to reprint material from this book
is granted on condition of full credit given to
the Montana Department of Fish and Came
and the Bureau of Land Management
First Printing

FOREWORD

To the casual observer, vegetation appears to be a random assortment of various plant
species, arranged by a mosaic of plant communities into a pleasant landscape. While the
pattern of vegetation types may appear to be random, the relationship between a site
and its associated vegetation is actually a very specific and predictable one, with site
potential resulting from the subtle blend of soil, topography and climate.

Needless to say, the more knowledge a land or wildlife manager has of the intimate
relationship between site and vegetation, the better he will be able to manage. This
bulletin presents a habitat type classification system for a portion of the plains region of
central Montana, an extension of the habitat type concept already in wide use in the
mountain and foothill areas. This information should prove useful to anyone interested in
a better understanding of Montana's vegetation resource.

Eugene O. Allen

Wildlife Division Administrator

Montana Department of Fish and Game

ACKNOWLEDGMENTS

This bulletin reports findings of an inventory associated with a 10-year cooperative
project between the Montana Department of Fish and Game (F&C) and the U S. Depar-
ment of the Interior (USDI), Bureau of Land Management (BLM) Larry Eichhorn from the
Lewistown office of the BLM provided valuable assistance, advice, and cooperation in
starting and maintaining this project

Thanks are due all ranchers in the Yellow Water Triangle area on whose land sampling
and reconnaissance were conducted. These include Bob Ahlgren, Henry Algra, Dorothy
Bartlett, Wayne Bratten, Bill Degner, Bud Cjerde, John Hughes, Andrew Iverson, Joe
King, Tony Mlekush, Nebraska Feeding Co , lonas Olson, Robert Raundal, John Schultz,
John Sibbert, and personnel of Teigen Land & Livestock Co Special thanks are given the
BLM, Bud Gjerde, John Hughes, Andrew Iverson, Joe King, John Schultz, Teigen Land &
Livestock Co , and the Winnett Grazing District for allowing placement of permanent
vegetation sampling markers on their land

Special appreciation is due to Duane Pyrah for his advice on procedures, insight into
habitat type relationships and editorial comments. F&G personnel who provided editorial
assistance were Eugene O. Allen, Richard J Mackie, Thomas W. Mussehl, and Richard O
Wallestad Persons from outside the Department providing technical advice and/or
editorial assistance were Stephen Arno, Rexford Daubenmire, Duane Ferdinand, James
Habeck, Richard Kerr, Don Mcintosh, Mel Morris, Robert Pfister, Edward Schlatterer, and
Warren Whitman Field data were gathered by Archie Bell and Terry McEneaney Work
on habitat type maps was done by Lauren Reuter and Les Reichelt. The Bureau of Indian
Affairs provided the use of equipment for making maps.

Ernest Hogan, U.S. Department of Agriculture (USDA), Soil Conservation Service (SCS),
provided descriptions and maps of soils found in parts of the area studied

Kay Ellerhoff and Donita Sexton were responsible for final editing, proofreading,
publication design, layout and liaison with the printer.

TABLE OF CONTENTS

LIST OF FIGURES vi

LIST OF TABLES vii

INTRODUCTION 1

DESCRIPTION OF STUDY AREA 3

Location and Physiography 3

Geology and Soils 4

Climate 5

Land Use 5

METHODS 8

DISCUSSION 10

Habitat Types and Phases of the Yellow Water Triangle 10

Shrub-Grasslands 11

Artemisia Series

Artemesia tridentata/Agropyron spicatum Habitat Type,

Bouteloua gracilis Phase 11

Artemisia tridentata/Agropyron spicatum Habitat Type,

Agropyron smithii Phase 13

Artemisia tridentata/Agropyron dasystachyum Habitat Type,

Agropyron spicatum Phase 13

Artemisia tridentata/Agropyron dasystachyum Habitat Type,

Sarcobatus vermiculatus Phase 14

Artemisia tridentata/Koeleria cristata Habitat Type 15

Atriplex dioica/Cutierrezia sarothrae Habitat Type 16

Artemisia tridentata/Festuca idahoensis Habitat Type,

Bouteloua gracilis Phase 16

Rosa arkansana/Thermopsis rhombiiolia Habitat Type 17

Artemisia cana/ Agropyron smithii Habitat Type 18

Sarcobatus Series

Sarcobatus vermiculatus/Agropyron dasystachyum

Habitat Type 19

luniperus Series

juniperus horizontalis/Carex parryana Habitat Type 19

Wetlands 20

Riparian Series

Populus deltoides/Symphoricarpus occidentalis Habitat Type 20

Scirpus/Carex Habitat Type 21

Suaeda/Salicornia rubra Habitat Type 21

Grasslands 30

IV

Agropyron spicatum/Agropyron smithii Habitat Type 30

Muhlenbergia cuspidata/Andropogon scorparius Habitat Type 31

Poa pratensis/ Artemisia ludoviciana Habitat Type 31

Coniferous Forest 32

Pinus Series

Pinus ponderosai 'Artemisia tridentata Habitat Type 32

Pinus ponderosai Agropyron spicatum Habitat Type 32

Distribution of Important Taxa

Artemisia tridentata 33

Agropyron spicatum 34

Agropyron smithii 35

Stipa comata 35

Stipa viridula 36

Bouteloua gracilis 36

Koeleria cristata 37

Poa sandbergii 37

Agropyron dasystachyum 37

Artemisia frigida 38

Vicia americana 38

Taraxacum officinale 39

Tragopogon dubius 39

Selaginella densa 39

Habitat Types and Management 40

Effects of Crazing on the Artemisia tridentata/ Agropyron
spicatum Habitat Type, Bouteloua gracilis Phase, and the Artemisia

tridentata/ Bouteloua gracilis Cover Type 40

Effects of Cultivation on the Artemisia tridentata/ Agropyron
spicatum Habitat Type, Bouteloua gracilis Phase, and the Artemisia

tridentata/ Bouteloua gracilis Cover Type 42

Effects of Crazing on the Artemisia tridentata/Agropyron

dasystachyum Habitat Type, Agropyron smithii Phase 43

Effects of Crazing and Cultivation on the Sarcobatus

vermiculatus/Agropyron dasystachyum Habitat Type 43

Effects of Grazing and Cultivation on the Agropyron spicatum/

Agropyron smithii Habitat Type 43

LITERATURE CITED 44

APPENDIX 49

LIST OF FIGURES

1. Yellow Water Triangle, Montana 3

2. Annual mean temperature and precipitation in the Yellow Water Triangle. . 6

3. Distribution of the Artemisia tridentata/Agropyron spicatum Habitat Type,
Bouteloua gracilis Phase 22

4. Distribution of the Artemisia tridentata/Agropyron dasystachyum Habitat Type,
Agropyron spicatum and Sarcobatus vermiculatus Phases, and the Rosa
arkansana/Thermopsis rhombifolia Habitat Type 22

5. Distribution of the Artemisia cana/ Agropyron smithii Habitat Type 22

6. Distribution of the Sarcobatus vermiculatus/ Agropyron dasystachyum Habitat
Type 23

7. Distribution of the Juniperus horizontalis/Carex parryana Habitat Type .... 23

8. Distribution of the Populus deltoides/Symphoricarpus occidentalis Habitat
Type 23

9. Distribution of the Agropyron spicatum/ Agropyron smithii Habitat Type, and

the Muhlenbergia cuspidata/Andropogon scoparius Habitat Type 24

10. Distribution of the Pinus ponderosa/ Artemisia tridentata Habitat Type 24

11. Distribution of the Pinus ponderosa/ Agropyron spicatum Habitat Type .... 24

LIST OF TABLES

1. Soils descriptions (Gieseker 1953; Soil Conservation Service, unpublished,
1966) 7

2. Percent canopy coverage comparisons between adjacent grazed and ungrazed
stands 41

APPENDIX A TABLES

1. Percent constancy and percent canopy coverage of all sampled species by
habitat types and phases 49

2. Species symbols and common names 53

3. Vegetation type areas of the Yellow Water Triangle 55

APPENDIX B TABLES

1. Glossary 57

INTRODUCTION

Effective and efficient management of rangeland resources requires an understand-
ing of existing natural and disturbed vegetation and the relationships of the component
plant species and communities to various environmental factors and forces. It also re-
quires an understanding of the potential of various land units to support various kinds and
amounts of vegetation. Before this knowledge can be useful to the land manager, how-
ever, it must be organized into some sort of vegetation or land unit classification system.

Vegetation classification, as opposed to ordination, provides a basis for vegetation
mapping, the usual first step in range surveys and development of management plans, as
well as for evaluating other resource values such as wildlife habitat (not to be confused
with vegetation habitat types). Classification also provides a framework within which
results of local studies can be correlated, as well as point out gaps in knowledge and indi-
cate new avenues of needed research or management effort. Basic knowledge of succes-
sional patterns and relationships of important plant species and communities to climatic
and disturbance factors, together with information on site potentials, can provide re-
source managers with a means of readily and effectively predicting expected vegetation
trends or changes under various management practices.

Vegetation classification efforts in the steppe regions of eastern and central Montana
have been few, limited in area, and varying in approach. Attempts to classify vegetation in
the Montana steppes, or in climatically similar regions, include: Coupland (1950, 1961)
and Looman (1963) in the mixed prairie of southern Saskatchewan; Hanson and Whitman
(1938), Quinnild and Cosby (1958) and Dix (1958) in the mixed prairie of western North
Dakota; Brown (1971) in the badlands of southeastern Montana; Mackie (1970) in the
Missouri River Breaks of central Montana; Wright and Wright (1948) in the sagebrush
grasslands of south central Montana; Daubenmire (1970) in eastern Washington, and
Harniss and West (1973) in southeastern Idaho.

While potential vegetal composition varies continually with one or more environ-
mental factors, gradients between areas with dissimilar topoedaphic conditions (ecologic
units) are usually relatively abrupt as compared to gradients within these ecologic units.
Because of the apparent strong relationships between vegetation and topoedaphic con-
ditions, vegetation of the Yellow Water Triangle was treated as a mosaic of associations
correlated with site conditions and disturbance factors, i.e., grazing and fire. The classi-
fication system presented in this paper is somewhat of a compromise between association

and continuum philosophies wherein data were gathered assuming that vegetal compo-
sition varied continuously over space, while final analysis of data involved both objective
and subjective attempts to classify the continuum into associations (habitat types).

The concept of habitat type classification, where a climax vegetation association de-
velops in response to climatic and topoedaphic conditions, was first applied to vegetation
of eastern Washington and northern Idaho by Daubenmire (1952, 1970). Similar systems
have been applied to the forests of Montana by Pfister et al. (1977) and to the mountain
grass and shrublands of western Montana by Mueggler and Handl (1974). An attempt has
been made here to maintain continuity with these systems. This system is also similar,
albeit with different nomenclature, to a vegetation-soil-climate classification system
developed by Ross and Hunter (1976) and currently in use by the USDA-SCS. The SCS
"range site" seems essentially equivalent to the term "habitat type" as used here. The
term "ecologic land unit" (a combination of land type and habitat type), as used by
Thompson et al. (1976) of the USDA-Forest Service, Region One, is apparently very similar
to the term "habitat type" used in this paper.

This study was initiated during summer 1970. Results were originally intended to assist
in the determination of pronghorn antelope and livestock habitat relationships and to aid
in evaluation of the ecological effects of chemical and mechanical control of big sage-
brush in central and eastern Montana. Just as important, however, the study isseen as the
first phase in the development of the philosophies and techniques to be used in a habitat
type classification system for the plains area of Montana. Since completion of the triangle
habitat type classification system, subjective approximations have been devised for
various areas through the plains province (covering approximately 171,000 km2 [66,023
mi.2] of Montana), with the hope that the entire area can eventually be classified.

While vegetation similar to that of the triangle probably occurs in adjacent areas of
central Montana, and possibly other parts of eastern Montana, it must be emphasized that
this classification system was not intended for application any place except the area on
which sampling was conducted (the triangle). A key for use by personnel in applying the
classification system was purposely not devised in order to discourage use of the system in
other areas. The only parts of this system meant to be used by workers in other areas, at
least without extensive study, are the habitat type concept and the techniques of data
gathering and analysis.

DESCRIPTION OF STUDY AREA

Location and Physiography

The triangle lies in east central Montana between U.S. Highway 87, Montana High-
way 200 and Route 244, and between the towns of Winnett and Grassrange (Fig. 1).
Lewistown, the geographical center of the state, lies 48 km (30 mi.) west of the north-
western corner of the triangle, while Billings is about 113 km (70 mi.) south of its southern-
most tip. The triangle encompasses an area of approximately 689.7 km2 (266.3 mi.2) of
which 62 per cent is in Petroleum County and 38 per cent in Fergus County.

The area is partially bounded by two perennial streams, McDonald and Flatwillow
creeks, originating in the Judith and Snowy mountains uplift and flowing intothe Mussel-
shell River east of the triangle. McDonald Creek bounds the triangle on the north and
Flatwillow Creek flows past the southern and a portion of the eastern borders of the area.
Several intermittent streams originate near the western side of the triangle and flow to the
east (Fig. 1). Bodies of water are restricted to man-made reservoirs, the largest being
Yellow Water Reservoir (85 hectares [211 acres]).

The highest elevations in the triangle occur in that portion of the Snowy Mountains

GRASS
RANGE

-T.I5N

INNETT

-T.I4N

-T.I3N

- T.I2N

R.24E

R.25E

R.26E

Figure 1. Yellow Water Triangle, Montana.
3

uplift protruding into the western part of the area (Fig. 1). Button Butte at 1,372 meters
(4,500 ft.) is the highest point. The high, gravel-capped bench south of Pike Creek in the
southwestern quadrant attains elevations slightly over 1,220 meters (4,000 ft.). The lowest
elevation is at the town of Winnett where McDonald Creek crosses Route 244. Elevations
along Route 244 increase progressively from McDonald Creek to Flatwillow Creek (Fig. 1).

Geology and Soils

Most of the triangle area (Figs. 3-11) is underlain by Cretaceous strata of the Colorado
shale formation (Reeves 1927, Johnson and Smith 1964), lying directly exposed or covered
by a relatively thin solum. In many locations, the Colorado shale strata are buried beneath
one or more layers of gravel originating from the Judith and Snowy mountains during the
Pleistocene ("Ice Age") Epoch. To the west (stratigraphically below) of the outcroppings
of Colorado shale is the Kootenai formation surrounding Button Butte (shown as "highest
point" in Fig. 1). Numerous igneous intrusions (plugs, dikes, and sills) of apparent Eocene
age occur throughout the triangle.

The various geological substrates support distinctive vegetation associations. Each
formation comprises several subunits (members); each, upon weathering, produces a
different type of soil and, in turn, different plant compositions.

The definite boundaries between geological substrates with their characteristic vege-
tation facilitated differentiation and mapping of habitat types. The boundary separating
habitat types on the upper members of the Colorado shale formation from those on the
lowest member of the Colorado shale (and all of the Kootenai formation) is especially
distinct due to the abrupt and complete disappearance of Artemisia tridentata as one
travels from east to west across the area.

Following are descriptions of the geological substrates of the triangle (from Johnson
and Smith 1964). Listed under each substrate are the names of soil types. In many cases,
these are obsolete names used by Gieseker (1953). Much of the soils nomenclature has
been changed since then, and updated information is not available for the bulk of the
triangle. However, updated information and nomenclature are available for some parts of
the triangle as a result of a soil survey done by the SCSon sagebrush treatment areas of this
project. Soil names from this survey are indicated by asterisks.

I. Strata of the Colorado shale formation (from east to west. Cretaceous)

A. Niobrara member — olive gray shale with limestone and sandstone concre-
tions and some bentonite. Soil — Lismas clay, Thebo clay*(?)

B. Carlile member — dark gray shale with limestone concretions in upper part
and red ironstone concretions in lower part. Soils — Lismas clay, Delpine-
Fields silty clay loams*

C. Calcareous shale member — gray calcareous shale weathering white.
Soils — Yawdim and Cabba soils*

D. Mosby sandstone member — ledge-forming sandstone with a shale layer.
Soils — Lismas clay

E. Belle Fourche member — dark gray shale with bentonite beds and black
ironstone concretions in lower part. Soils — Thebo-Lisam clays*, Bercail
clay loam*

F. Mowry member — gray siliceous sandstone weathering white. Soils — ?

G. Unnamed sandy member — gray sandy shale with yellowish gray sandstone.
Soils — Thebo clay*, Maginnis clay loam, Martinsdale loam and gravelly
loam

H. Skull Creek member — gray shale with some yellowish gray sandstone in
lower part. Soils — Thebo clay*(?), Maginnis clay loam

I. Lower sandstone member— gray to yellowish brown sandstone. Soils —
Castner-Morton loams and stony loams

II. Kootenai formation (Cretaceous, undifferentiated) — ledge-forming metamor-
phosed sandstone layers interbedded with red shale. Soils — Castner-Morton loams
and stony loams, Cushman loam, Darrett loam and stony loam

III. Ellis formation (Jurassic, undifferentiated)— mostly flaggy sandstones. Soils— not
known

IV. Quadrant formation (Mississippian, undifferentiated) — limestones and shales.
Soils — not known

V. Terraces — gravel-capped tables with gravel layers a few feet to 15 or 20 feet thick.
Soils — Phane and Gerdrum soils*, Gerdrum and Tealer clays*, Woodhawk and
Verson clay loams*, Marias silty clay*, Verson and Warrick clay loams*, Cargo
gravelly loam*, others

VI. Alluvium — material eroded from uplands and redeposited in bottomlands. Soils —
Absher and Nobe soils*, Billings-Arvada clay loam, others

VII. Igneous intrusions — hard fractured rock near the surface with shallow soil mantles.
Soils — ? Since there has been no detailed soils survey made on these geological
types, no soil names can be listed.

Climate

The climate of the triangle area is semiarid and cool with great extremes in tempera-
ture. Grassrange receives significantly higher annual precipitation than Flatwillow, but
mean annual temperatures are similar (Fig. 2). The precipitation difference may be caused
by the proximity of Grassrange to the Judith and Snowy mountains uplift. Slightly lower
summer temperatures at Grassrange as compared to Flatwillow may be due to the higher
elevation of Grassrange — 1,061 vs. 956 meters (3,481 vs. 3,136 ft.). Some portions of the area
(i.e., Button Butte) in the western part of the triangle are over 300 meters (984 ft.) higher
than Grassrange with cooler summer temperatures and greater precipitation than Grass-
range (Fig. 2).

Both stations exhibit continental patterns of precipitation with a sharp maximum in
early summer (Fig. 2) and a minimum during the winter. On the average, 40 per cent of the
total annual precipitation falls during May and June and 75 per cent occurs through the
growing season (April-September).

The average freeze-free season ranges from 115-125 days (between 25 May and 17
September) (Caprio 1964).

Land Use

Approximately 16,625 hectares (41,050 acres), or 24.1 per cent of the triangle is
administered by the USDI's BLM; the remainder is in private or state ownership. Most of
the public land of the triangle is in Petroleum County and is fairly evenly distributed. Some
public land is leased to individual landowners and some is under a common use arrange-
ment between several ranchers. An area of public land around Yellow Water Reservoir is
designated as the Yellow Water National Wildlife Refuge, administered by the USDI's Fish
and Wildlife Service, but it is mainly used for livestock grazing.

Presently, most of the triangle is grazed by cattle with some small areas in cultivation
of hay or grain. Total area planted to grain in 1970 (estimated from aerial photographs) was
998 hectares (2,471 acres); approximately 3,400 hectares (8,400 acres) of land was in alfalfa
and hayfields.

The intensities and periods of grazing were and are extremely variable across the
area; grazing in the past was characterized by greater numbers of livestock, longer
periods of use, and more sheep than at present.

FLATWILLOW

6RASSRAN6E

Annual T°

45.1° F.
7.3° C

44.0° F#
6.6°C*

Annual Ppt.

12.97 in.

15.74 In.

529 mrr

400 mm

■ ■

F/1

M J J A S 0 NXnD

o

o

25 ^

UJ

oc

r-
<

UJ

Cl

UJ

r-

X

r-

-20

-15

-10

- -5

^-10

<
UJ

Figure 2. Annual mean temperature and precipitation in the Yellow
Water Triangle.

TABLE 1.-

-Soils Descript

ions

(Gieseker 1953,

SCS

unpublished 1966*;

Width

Width

Color

Texture

Texture

Nature

Depth

of

of

of

of

of

of

of

A

B

A

A

B

Parent

Name

Solum'

Horiz.'

Horiz.3

Horiz."

Horiz."

Horiz."

Material'

Salinity

Other Characteristics

Lismas C

6

1-2

4-5

grsh
Brwn.

SiC

C

Clay

shale

Low

Non-calcareous

Delplne —

38

3

None

dk.

SiCL

_

True

None

Non-calcareous

Fields CL"

Gr.

platy shale

Yawdim-

12

3

None

Gr.-

L-SiCL

_

Soft shale

None

Moderately calcareous

Cabba soils"

It. Brwnsh.
Gr

Thebo-

24-

5

None

grsh.

C

_

Clay

Gypsum in"

Clay vertic* entisols

Lisam C*

42

Brwn.

shale

C horizon

Maginnis

10-

6

None

grsh.

CL

_

Platy shale

None

Non-calcareous

CL

15

Brwn.

Martinsdale

36

5-7

1-13

Brwn.

L

Grav.

Gravel

None

L & gravelly L

L

and sand

Castner-

8-30

4-7

0-11

dk

Stony

LorCL

Shaly

None

Calcareous B horizon

Morton L &

grsh.

L

SS

stony L

Brwn

Cushman L

36

5-7

3-13

grsh.
Brwn.

L

LorCL

Sandy shale

None

Darrett L

24-

6-10

2-9

rdsh.

LorCL

CL

Red shale

None

Calcareous C horizon

and stony L .

36

Brwn.

and SS

Phane"

15-
23

1-3

9

grsh
Brwn.

L

C

CLorC
alluv.

None

Gravel begins below 20"

Woodhawk"

5 ft.

3-5

8-14

grsh.
Brwn.

CL

C

CLorC
alluv.

Below 30"

Gravels throughout, gypsum at
55-60" soft vesicular crust on
A1'°, lower part of B is cal-
careous

Gerdrum

5 ft.

A2-2"

27

Brwnsh
Gr.

VFSL

C

C underl.
by grav.

Solodic,
pH8-9"

Columnar Bt" horizon, gypsum
at 18-60", no gravel above 40"

Tealer C*

5-6ft

A2-1"

23

Brwnsh.
Gr.

L

C

C alluv.

Solodic B and
C horiz. pH 8-9

Gypsum at 11-60", slick spots

Verson CL'

25

1-2

19

grsh.
Brwn.

L

C

C alluv. and
limestone gravel

None

Lime at 17-42", gravel begin-
ning at 17"

Bercail CL "

34

4

20

grsh.
Brwn.

CL

C

C alluv. and
C shale

None

Very calcareous B horizon

Cargo

5

5

None

grsh.

L

_

Gravel

None

Calcareous throughout, crowns

gravelly L*

Brwn.

of benches, gravel throughout

Warrick"

26

3

21

Brwnsh.
Gr.

L-SiL

c

Cor CLon
gravel

Gypsum at
26-46"

Gravel below 40"

Marias SiC"

24

4

14

grsh.

Brwn.

SiC

SiC

C alluv.

None

On fans and terraces

Absher CL"

9

A2-2"

4

It.

Brwnsh.

Gr

L

c

Cand CL
alluv.

Very saline
below 5" pH
7.8-8.6

Columnar B2t" horizon, on low
terraces

NobeC"

4

AM"

3

grsh.
Brwn.

C

c

Cor CL
alluv.

Saline below
6" pH 8.5-9

Natric, vesicular crust, on ter-
races, fans and bottomlands

Billings-

8-10

1-2

6-8

Lt. Gr.

CL

c

CorCL

Saline and

Poor to moderate drainage, on

Arvada C

to Gr

alluv.

possibly

alkaline

bottomlands

"Soils on treatment areas described in detail by Soil Conservatio

n Service

'The depth of the solum is the depth to the parent material (mate

rial from v

<hich the soil is forme

d), in inches unless

otherwise noted.

'If the A horizon is dark, it is called "topsoil."

'"Subsoil "

"If the horizon is dark (A1) it indicates a non-alkaline, non-saline

soil with c

jnsiderable organic m

atter in the topsoil.

If the horizon is light (A2), the soil is possibly saline, alkaline, o

calcareoi

s (grayish-brown is d;

irker than brownish

gray).

"C-Clay, Si-silt, S-sandy, L-loam, Gr.-Gray, grsh. -grayish, Brwn.-br

own, Brwn

sh. brownish, It-light

SS-sandstone, dk.-<

lark, VF-very fine, rdsh. -reddish.

"Clay "B" horizons signify the presence of subsurface claypans \

vith assoc

ated poor water and r

oot penetration.

'Soil-forming material.

"Gypsum indicates possible salinity but not alkalinity.

"Heavily cracked soils subject to heaving and "self-plowing."

'"A vesicular crust indicates very poor water and air permeability

"Soils with pH below 8.4 may be saline but are not alkaline. Soi

s with pH

above 8.4 are alkaline

and may be saline.

"A very fine-textured B horizon

METHODS

Any attempt to classify vegetation begins with a subjective approximation. The first
step in this approximation was to travel the area, becoming familiar with plant species,
vegetal communities, topography, geology, and soils. Although the author was able to
identify on sight most of the plants of the region, some use was made of a reference plant
collection. Identification of most plants in this collection was verified by Edwin E. Booth,
curator of the Montana State University Herbarium at the time. Species identification
procedures followed the keys in Booth (1950), and Booth and Wright (1959); nomencla-
ture follows these references or Hitchcock and Cronquist (1973), with the latter given
preference. Common names of all sampled species are given in Appendix A Table 2.

The initial approximation was followed by a more intensive reconnaissance. Notes
were taken on vegetal composition, relative species dominance, gross soil characteristics,
geology, slope, aspect, apparent grazing intensity, and the exact locations of approxi-
mately 350 reconnaissance sites throughout the triangle. These sites were chosen sub-
jectively and represented distinct topoedaphic units as seen on 1:15840 black and white
aerial photos taken in 1970. At the time of reconnaissance, the vegetation continuum was
subjectively broken down into broad types on the basis of gross physiognomy. Some
riparian, wetland, and forest types were not analyzed further except to make species lists.

By this time, it was possible to recognize (aided by literature and geological maps of
the area) different strata of the Colorado formation, the Kootenai formation, gravel
benches, and igneous intrusions. Easily recognizable soil characteristics of importance to
plants were: texture and organic matter content of the topsoil, clay content, stoniness,
salinity, self-plowing tendencies, permeability, and in some cases, depth of the solum.
Other characteristics were judged from information available in literature, soil surveys,
and maps. Soils information was derived from a combination of unpublished SCS descrip-
tions, general observations from soil profiles exposed by soil pits or erosion, and observa-
tions of the surface characteristics previously mentioned. Detailed soils information is
lacking for most of the triangle and gathering detailed and quantitative soils data was
beyond the scope of this study. While some gross relationships between soil and vegeta-
tion could be deduced, no formal or detailed attempt was made to correlate plant
communities with soil characteristics.

The subjective approximate classification was then objectively refined. Seventy-five
stands (not included in the original 350 reconnaissance sites) were chosen throughout the
area, attempting to choose one or more sampling locations from each topoedaphic entity
(except riparian and wetland) as seen on 1:15840 aerial photographs. Once these stands
were located on the ground, a macroplot, which appeared to be homogeneous and rela-
tively representative of the stand, was laid out. This macroplot consisted of one or two
30-meter lines, along each of which twenty 2x5 decimeter microplots were evenly
spaced. A percentage indicating frequency of occurrence of each species was deter-
mined for each stand. Canopy coverage of all plant species, and the area coverage of
mulch, rock, and bare ground, were estimated using a slightly modified version of the
canopy coverage estimation method used by Daubenmire (1959). An attempt was made to
sample stands that seemed relatively less heavily grazed (as judged by apparent vigor of
plants, presence of considerable litter and mulch, and a relative lack of grazing-increaser
plant species) than the triangle in general. Some heavily grazed, or otherwise disturbed,
stands were specifically sampled to try to determine the effects of such disturbance. Each
sample site was permanently field marked and recorded on aerial photographs.

Once these data were gathered, initial classifications were refined by arranging the
stand vs. species frequency tables in similar groupings (association tables). Frequency
rather than canopy coverage data were used for this because it was believed that fre-
quency data were less subject to year-to-year fluctuations resulting from short-term
differences in grazing intensity and weather.

Final refinement of the approximation was accomplished by computing indices of
similarity between all stands within physiognomic groups, and placing all indices in a
matrix with similar stands arranged adjacent to each other (Sneath and Sokal 1962). The
index of similarity used was a modification, by Spatz, of Jaccard's community coefficient as
reported in Mueller-Dombois and Ellenberg (1974).

In the final classification, the habitat types and phases were grouped within more in-
clusive categories referred to as series. As mentioned above, these larger categories were
chosen subjectively and based on gross physiognomy or life form. Floristic composition of
potential vegetation associations (if indeed, associations exist at all) could not be ascer-
tained due to a lack of historical records, a lack of representative relict areas in all ecologic
units, and a history of vegetal change over the entire area resulting from heavy grazing.
Therefore, descriptions of potential vegetation associations were made using certain
assumptions based on known reactions of taxa to various treatments; information from
other studies concerning the relationships between plants, edaphic factors, and grazing
pressure, and the descriptions of vegetation associations in similar areas by other workers.

A classification system is no better than the quantity and quality of data it is based on,
and even the best one must be considered an approximation subject to future change as
relationships between plant communities and various influencing factors are better
understood. This does not mean, however, that an approximation is not useful or worth-
while. This study, for example, has produced a valuable land management tool in spite of
the problems mentioned in the preceding paragraph and certain limitations inherent in
the overall objectives and scope of the study. The techniques described here are adequate
to turn the concept of the habitat type approach for vegetation classification into a useful
system for the vegetation of eastern Montana. Any further attempts at classifying vegeta-
tion regionwide on a topoedaphic basis, however, will require a much more rigorous
approach including quantitative soil-slope sampling as well as phytosociological studies
(i.e., ordination). Because of the importance of all habitat types to livestock and wildlife,
future work should also include intensive sampling in and the description of all habitat
types, including riparian, wetland, and forested.

DISCUSSION

Habitat Types and Phases of the Yellow Water Triangle

The triangle is not a homogeneous area with respect to climate or geology. The pre-
cipitation gradient from east to west across the area, and the radically different geology of
the east side compared to the west side, causes thetriangletostraddletwo major biologic
zones — the mixed prairies and the foothill grasslands and forests. Because of this, the area
represents a kind of transition between the two zones and probably cannot be considered
as typical of either one.

Triangle vegetation was classified both according to habitat types and existing cover
types. Daubenmire (1952) defined "habitat type" as "the collective area which is capable
of supporting the same homogeneous plant association." This involves a consideration of
the abiotic as well as biotic features of the system, including climate, soil, topography, fire,
and native animal influences; effects of man and his animals are not considered. A de-
scription of the vegetation of a habitat type is the description of the potential vegetation
were the site not disturbed; however, such potential vegetation presently exists only on
small, isolated relict sites.

The actual vegetation covering a site that has been disturbed is called the cover type.
These cover types are the result of heavy grazing pressure by livestock, and/or cultivation,
and are susceptible to changes in species composition when management is altered. As
will be discussed later, some apparent types may be fire climaxes resulting from events
occurring periodically throughout history. A discussion of cover types and successional
changes to be expected within the major habitat types is found later in the discussion of
habitat types and management. Some areas of the triangle are undergoing primary suc-
cession, at least this was the case before man accelerated the rate of soil erosion to the
point where it was more rapid than soil development. Many parts of the triangle, with a
few decades of overgrazing and poor farming practices, evidently losttopsoil formed over
thousands of years (Ellison 1960, Noble 1969, and Hormay 1970). Evidences of past erosion
can be seen in extensive raw gully formation, plant pedestalling, and formation of erosion
pavements. Since hundreds or thousands of years will elapse before these areas could
again support pristine vegetation (if such is desired), the potential vegetation associations
for these sites should be considered early stages of primary succession; these associations
are stable and highly adapted to the present rather than original (more highly developed)
soils.

Vegetation over the area is in all stages of secondary succession due to different de-
grees of livestock grazing pressure. Areas experiencing light pressure over a number of
years, and not severely damaged by past erosion, probably indicate what the potential
vegetation should be. Other places have had so much accelerated erosion that, for the
most part, a new site potential, different from what it was before the arrival of the white
man, has been established.

Overgrazing, by removal of soil-protecting litter (mulch) and vegetation cover,
increases water run-off from uplands (Adams 1966, Noble 1969, and Whitman et al. 1964)
tending to strip the topsoil from adjoining low-lying areas. Following a long period of such
accelerated erosion, some low-lying areas probably bear little resemblance to what they
were before livestock grazing began. In this way, extreme livestock grazing pressure on
some areas has led to the destruction or complete change of soil and vegetation on loca-
tions miles away (Shantz 1935, Jacks and Whyte 1939).

Appendix A Table 3 lists coverage of vegetation types. Area coverage was estimated
using the dot grid method on 1 :1 5840 aerial photographs which had the habitat types out-
lined. Appendix A Table 1 shows canopy coverage of important taxa in each habitat type
where data were gathered. The relationships between major habitat types or phases with
geology are shown in Figures 3-11. Not all habitat types described are shown.

The habitat and cover types of the triangle occupying the greatest area may be
divided into three basic categories according to life form of the dominant plants: (1)
shrub-grassland, (2) coniferous forest, and (3) grassland. Another category includes the
wetland types. Naming of habitat types and phases was done using both constancy
(percent occurrence of species by stands) and canopy coverage data, with constancy

10

being given more weight. Further subdivisions provide series and habitat types as follows:
Hierarchy of Yellow Water Triangle Vegetation Classification (species names and
symbols) are given in Appendix A Table 2

I. Shrub-grasslands

A. Artemisia Series

1. Artemisia tridentata/Agropyron spicatum Habitat Type, Bouteloua gracilis
Phase

2. Artemisia tridentata/Agropyron spicatum Habitat Type, Agropyron smithii
Phase

3. Artemisia tridentata/Agropyron dasystachyum Habitat Type, Agropyron
spicatum Phase

4. Artemisia tridentata/Agropyron dasystachyum Habitat Type, Sarcobatus
vermiculatus Phase

5. Artemisia tridentata/Koeleria cristata Habitat Type

6. Atriplex dioica/Gutierrezia sarothrae Habitat Type

7. Artemisia tridentata/Festuca idahoensis Habitat Type, Bouteloua gracilis
Phase

8. Rosa arkansana/Thermopsis rhombiiolia Habitat Type

9. Artemisia cana/ Agropyron smithii Habitat Type

B. Sarcobatus Series

1. Sarcobatus vermiculatus/ Agropyron dasystachyum Habitat Type

C. Juniperus Series

1. juniperus horizontalis/Carex parryana Habitat Type

II. Wetlands (not subdivided into series)

1. Populus deltoides/Symphoricarpus occidentalis Habitat Type

2. Scirpus/Carex Habitat Type

3. Suaeda/Salicornia rubra Habitat Type

III. Grasslands (not subdivided into series)

1. Agropyron spicatum/ Agropyron smithii Habitat Type

2. Muhlenbergia cuspidata/ Andropogon scoparius Habitat Type

3. Poa pratensis/ Artemisia ludoviciana Habitat Type

IV. Coniferous Forest
A. Pinus Series

1. Pinus ponderosa/ Artemisia tridentata Habitat Type

2. Pinus ponderosa/ Agropyron spicatum Habitat Type

Shrub-Grasslands

Artemisia Series

Artemisia tridentata/Agropyron spicatum Habitat Type
Bouteloua gracilis Phase

1. Floristic composition
11

Dominant — Artemisia tridentata, Agropyron spicatum, Bouteloua gracilis, Poa sand-
bergii, Stipa comata

Subordinate — Koeleria cristata, Agropyron dasystachyum, Artemisia frigida, Sela-
ginella densa, Carex stenophylla, Opuntia polyacantha, Vicia americana, Agropyron
smithii

2. Site — undulating uplands

3. Geology — Niobrara member (M), Carlile M, Mosby M, Belle Fourche M, Mowry M,
unnamed sandy M, Skull Creek M, terraces, igneous intrusions (Fig. 3)

4. Soil description — Well developed with mollic epipedon, deep solum, thin topsoil,
clay subsoil

5. Soil types — Lismas C, Delpine-Fields SiCI, Thebo-Lisam C, Bercail CI, Maginnis CI,
Martinsdale I, Phane, Gerdrum, Woodhawk, Verson, Marias, Warrick

6. Parent materials — various

7. Relative productivity— high

8. Management — moderate or light grazing, no cultivation. Heavy grazing results in
replacement of Agropyron spicatum by Bouteloua gracilis. Conversion to grassland
is highly destructive to pronghorn and sage grouse habitat.

The Artemisia tridentata/ Agropyron spicatum habitat type, as originally defined by
Daubenmire (1970), exists only in Washington; vegetation associations in central Montana
dominated by these two species are considerably different in respect to the floristic
composition contributed by subordinate species. Therefore the Artemisia tridentata/
Agropyron sp/catum-dominated plant communities in this area are designated the
Bouteloua phase of the Artemisia tridentata/ Agropyron spicatum (Montana) habitat type
of Mueggler and Handl (1974).

The Bouteloua phase differs from Daubenmire's (1970) habitat type due to the pres-
ence of typical mixed prairie species: Bouteloua gracilis, Koeleria cristata, Opuntia polya-
cantha, Artemisia frigida, Gutierrezia sarothrae, Vicia americana, and Phlox hoodii. The
phase contains Stipa comata and Poa sandbergii as does Mueggler's and Handl's (1974)
habitat type.

The Artemisia tridentata-Agropyron spicatum association is found on relatively well-
developed soils formed from a variety of parent materials, and has probably had the
opportunity to reach a state of dynamic equilibrium under conditions of the prevailing
climate. Because of this apparent advanced state of development, the Artemisia triden-
tata-Agropyron spicatum association was considered to be the climatic climax for the
areas underlain by the Colorado shale formation. Agropyron spicatum usually, but not
always, occurs on soils with a dark topsoil. Some stands of Agropyron spicatum are situ-
ated on entisols (soils lacking horizon differentiation), although these are not considered
to be the same phase.

Because of wetter, springtime weather to the west, which is closer to the center of
origin of the species, Agropyron spicatum completes most of its growth in spring and early
summer (Blaisdell 1958, Pyrah 1972). The triangle may be a transition area between the
mixed prairie just to the east and the Agropyron sp/catum-dominated grasslands of the
Judith Basin and other areas to the west. Agropyron spicatum becomes increasingly re-
stricted to rocky hilltops as one travels east in Montana, finally disappearing in the western
Dakotas, whereas typical mixed prairie associations increase to the east. The upland soils
of the triangle appear to be more favorable for Agropyron spicatum (presumably mi-
grating in from the west) than for any other grass. Artemisia seems to be better adapted to
soils of the triangle and nearby areas underlain by the Colorado formation than it is tothe
soils of both the areas just to the west (underlain by the Kootenai formation) and the east
(underlain by the Eagle formation). Soils derived from both these formations support little
Artemisia tridentata, even when heavily grazed. The sandy soils of the Eagle formation are
highly favorable for Stipa comata; the vigor of this species on sandy soils is far greater than
on the generally clay or clay loam soils of the triangle.

Numerous areas without Artemisia tridentata may be found on the gravel terraces,
usually as a result of past and present fires occurring throughout the region during hot,

12

dry periods in late summer. Once burned, a stand of Artemisia tridentata in this region
does not re-establish for many years, leaving a perennial grass-dominated site. Most of
these burned areas are within the Artemisia tridentata-Bouteloua gracilis cover type and
are considered to be a variation of this type.

Artemisia tridentata/ Agropyron spicatum Habitat Type
Agropyron smithii Phase

1. Floristic composition

Dominant — Agropyron smithii, Artemisia ludoviciana, Stipa viridula
Subordinate — Artemisia tridentata, Taraxacum officinale, Tragopogon dubius

2. Site — swales and footslopes

3. Geology — terraces and tables, Lower Sandstone M

4. Soil description — Well developed with relatively thick dark topsoil, loam texture,
deep solum

5. Soil type — Syblon

6. Parent materials — alluvium

7. Relative productivity — very high

8. Management — moderate grazing, cultivation will result in gully formation. Conver-
sion to grassland is highly destructive of pronghorn and sage grouse habitat.
Contour-furrowing may temporarily reduce run-off and erosion.

Moisture collecting sites associated with the gravel-capped tables support a more
mesophytic vegetation composition than those receiving only the macroclimatic amount
of moisture. These sites include swales and footslopes of bluffs and hillsides. The soils are
deep with good moisture penetration, supporting dense swards of Agropyron smithii and
Stipa viridula, and numerous forbs such as Artemisia ludoviciana, Taraxacum officinale
and others. Artemisia tridentata is often absent in the middle of swales, possibly because
of severe competition from the dense grass cover.

Artemisia tridentata /Agropyron dasystachyum Habitat Type
Agropyron spicatum Phase

1. Floristic composition

Dominant — Artemisia tridentata, Agropyron dasystachyum, Agropyron smithii

Subordinate — Agropyron spicatum, Poa sandbergii, Koeleria cristata, Stipa viridula,
Vicia americana

2. Site — undulating uplands and gentle slopes

3. Geology — Niobrara M, Carlile M, Belle Fourche M, unnamed sandy M, Skull Creek
M, terraces (Fig. 4)

4. Soil description — poorly developed, shallow solums, little or no topsoil, clay texture
throughout, alkaline and possibly saline, self-mulching

5. Soil types — Lismas C, Thebo-Lisam C, Tealer

6. Parent materials — clay shale

7. Relative productivity — moderate

8. Management — little or no grazing, no cultivation.

This is called the Agropyron smithii phase of the Artemisia tridentata/ Agropyron
dasystachyum habitat type to distinguish it from a habitat type of the same name but with
somewhat different composition in southern Idaho (R. Daubenmire 1977, personal com-
munication). Soils formed directly over shale outcrops of the Colorado formation are
usually high in clay content and soluble salts. The salts normally include an excess of
sodium ions, adversely affecting soil physical properties (unless large amounts of calcium

13

ions are also present).

Clay soils forming over shales often lack horizon differentiation (where it is impos-
sible to separate out a topsoil layer and a subsoil layer in the profile). There are two reasons
for this: First, the soils are newly formed (young) and haven't had a chance to develop
horizons; second, these soils possess vertic tendencies (self-mixing), but not to the
extreme of being true "vertisols," caused by expansion and contraction, upon wetting
and drying, of bentonite clay. A soil with vertic tendencies is restrictive to the types of
plants able to grow in it. Ordinarily Agropyron spicatum is not abundant on vertic soils in
the triangle, possibly as a result of overgrazing rather than the inability of the plants to
grow in that type of soil. Heavy clay soils support an association dominated by Artemisia
tridentata, Agropyron dasystachyum, Agropyron smithii, and Agropyron spicatum plus
considerable Koeleria cristata, Stipa viridula, and Poa sandbergii. Coverage oi Agropyron
spicatum is usually less than in the Artemisia tridentata/ Agropyron spicatum habitat type,
Bouteloua phase, whereas coverage of rhizomatous forms of Agropyron is greater.
Agropyron spicatum is the dominant grass on some sites, possibly depending on the
degree of soil development. It appears that this habitat type could be an intermediate
stage of primary succession between the undeveloped soils of shale slopes and the well-
developed soils of the Artemisia tridentata/ Agropyron spicatum habitat type, Bouteloua
phase. Forb coverage is reduced and composition is different on this type of soil as
compared to soils of other Artemisia habitat types. Vicia americana occurs with somewhat
greater constancy than it does in the Artemisia tridentata/ Agropyron spicatum habitat
type, Bouteloua phase.

White and Lewis (1969) found the roots of Agropyron smithii and Stipa viridula are
constructed so that the outer layers (cortex) of the roots strip off when vertic soils crack,
leaving the roots unbroken. Many other species of plants do not survive in these soils
because the cracking movements break the roots.

Due to the dense clay surface, Bouteloua gracilis and Stipa comata are almost absent
from this habitat type even with heavy grazing. Selaginella densa is also nearly absent.

The Artemisia tridentata/ Agropyron dasystachyum habitat type, Agropyron spicatum
phase usually occurs on soils derived from shales of certain members of the Colorado
formation. Soils from various parts of these members also support the Artemisia triden-
tata/Agropyron spicatum habitat type, 8oute/oua phase, possibly due to a greater degree
of development.

Because a considerable amount of clay material was mixed with the gravel on gravel-
capped terraces or deposited over it, some sites on the terraces support vegetation more
adapted to a clay soil than normally expected. In some spots, the original parent material
apparently contained considerable sodium salts. Sodium ions disperse the very fine soil
particles, drastically slowing water penetration, thereby influencing the vegetation
composition. Water stands in these spots (called "slick spots"), eventually evaporating
rather than soaking in. The vegetation on slick spots appears to be an Artemisia tridentata-
Agropyron dasystachyum association (possibly similar to the Schedonnardetum pani-
culati association of Looman 1963) but with less Artemisia than in other areas.

Artemisia tridentata/ Agropyron dasystachyum Habitat Type
Sarcobatus vermiculatus Phase

1. Floristic composition

Dominant — Artemisia tridentata, Agropyron dasystachyum, Sarcobatus vermicu-
latus, Distichlis stricta

Subordinate — Iva axillaris, Gutierrezia sarothrae, Bahia oppositifolia

2. Site — rolling uplands and relatively steep hillsides

3. Geology — Niobrara M, Carlile M, Mosby M, Belle Fourche M, unnamed sandy M,
Skull Creek M (Fig. 4)

4. Soil description — usually clay or clay loam, alkaline and saline, often vertic, weak de-
velopment, ground water relatively near surface

5. Soil types — Thebo-Lisam C, Lismas C, others (?)

14

6. Parent materials — marine shales

7. Relative productivity — low

8. Management — Anything more than light grazing pressure will result in severe ero-
sion. Cannot be cultivated.

This phase occupies clay or clay loam soils usually where a ground water supply is
available to the Sarcobatus (Rickard 1965a, Branson et al. 1970). The ground water in these
locations is saline and usually alkaline (high in sodium and carbonate ions) with the salts
and water being translocated from the roots to the leaves of the Sarcobatus plants. When
the leaves fall from the shrubs, the salts contained therein are added to the surface of the
soil. Presumably in this way a non-saline, non-alkalinesoil surface with Sarcobatus bushes
and overlying saline-alkaline ground water can become saline-alkaline. A soil with a
surface layer that is at least non-saline (not necessarily non-alkaline) is apparently neces-
sary for the survival of Artemisia tridentata (Daubenmire 1970), and if something causes
this condition to change, the Artemisia may be killed. (For a discussion of the problems of
salinity and alkalinity in soils and their differences, see the staff publication of the U. S.
Salinity Laboratory 1954.) Rickard (1964) compared pH (measure of alkalinity), conduc-
tivity (measure of salinity), and exchangeable sodium percentage in the surface soil
beneath Artemisia and Sarcobatus bushes and found that all measurements were higher
under the Sarcobatus than the Artemisia. He concluded that salts were being added to the
soil by the Sarcobatus bushes and that these salts were killing adjacent Artemisia bushes,
since many of these plants were dead or dying.

The addition of sodium ions to the topsoil by Sarcobatus, in addition to accelerated
erosion resulting from overgrazing, has a detrimental effect on the physical properties of
the soil, reducing moisture penetration and thereby influencing the vegetation composi-
tion (Rickard 1965b). Possibly in all areas where both Sarcobatus and Artemisia exist, and
where the Sarcobatus is maintaining itself and reproducing, all of the Artemisia (and other
plants intolerant of saline-alkaline conditions in the surface soil) will eventually be elimi-
nated.

If the surface soil between Sarcobatus shrubs is not saline-alkaline, Artemisia triden-
tata, Agropyron dasystachyum, Iva axillaris, and Gutierrezia sarothrae will be found.
Where the canopy coverage of Sarcobatus is high, and the soil very saline-alkaline, the
dominant grass is Distichlis stricta and where saline-alkaline ground water approaches or
reaches the surface, thick stands of this grass are present. Daubenmire (1970) reports that
Sarcobatus and Distichlis are very tolerant of salinity in soils, Artemisia tridentata much
less so, and Agropyron even less than Artemisia. Artemisia is more tolerant of high alka-
linity than of high salinity.

Artemisia tridentata /Koeleria cristata Habitat Type

1. Floristic composition

Dominant — Artemisia tridentata, Koeleria cristata, Agropyron dasystachyum

Subordinate — Gutierrezia sarothrae, Phlox hoodii, Arenaria hookeri, Eriogonum
pauciflorum, Eriogonum (lavum, Carex filifolia, Agropyron spicatum, Vicia ameri-
cana, Petalostemon purpureum

2. Site — gentle upland slopes, crowns, and sides of gravel-capped terraces

3. Geology — calcareous shale M, edges of terraces

4. Soil description — weakly developed, shallow solum, Si or SiC texture may be gravelly,
calcareous

5. Soil types — Yawdim-Cabba, Cargo

6. Parent materials — calcareous silty shale, gravel

7. Relative productivity — very low

8. Management — Even very light grazing pressure will cause erosion. Cultivation will
result in severe erosion.

15

Immature soils derived from the calcareous shale member of the Colorado formation
support a distinctive vegetation type consisting solely of the Agropyron dasystachyum-
Carex filifolia association (apparently similar to Looman's 1963 Ehogonum flavi alliance).
In addition to the dominant species, Gutierrezia sarothrae, Phlox hoodii, Machaeranthera
grindeloides, Eriogonum pauciflorum, and Eriogonum flavum are common. Coverage of
bare ground is high and that of litter is low. Erosion potential appears high. The immature
nature of the soil and the types of plants present indicate that this habitat type is probably
in an early state of primary succession. In observing the habitat type from a distance, the
very low canopy coverage of Artemisia is striking when contrasted to sites on either side of
it; apparently Artemisia tridentata in this area does not thrive on silty, calcareous soils.

The crowns of gravel-capped terraces constitute a variation within this habitat type.
Although some notable differences in vegetation composition are evident, they are not
great enough to warrant creation of a different habitat type. The canopy coverage of all
species of plants is low, and that of bare ground and rock is high. In addition to Artemisia
tridentata and Agropyron spicatum, there are Muhlenbergia cuspidata, Carex filifolia,
and a large number of caespitose forb species (i.e., Arenaria hookeri, Phlox hoodii, and
Paronychia sessiliflora). This might be considered a Muhlenbergia cuspidata phase of the
Artemisia tridentata/ Agropyron spicatum habitat type.

A triplex dioica/ Gutierrezia sarothrae Habitat Type

1. Floristic composition

Dominant — Atriplex dioica, Gutierrezia sarothrae, Agropyron dasystachyum
Subordinate — Sitanion hystrix, Iva axillaris, Artemisia tridentata

2. Site — badlands, uplands, fans

3. Geology — Belle Fourche M, unnamed sandy M, Skull Creek M, alluvium from vari-
ous shale members

4. Soil description — very weakly developed, clay (bentonite), alkaline

5. Soil type — not known

6. Parent material — montmorillonite clay (bentonite) or clay alluvium

7. Relative productivity — nearly zero

8. Management — provides virtually no usable forage for livestock. Cannot be culti-
vated.

The Atriplex dioica-Gutierrezia sarothrae association comprises mostly Atriplex
dioica and little else. The soil varies from slightly altered bentonite to almost pure bento-
nite, is often saline-alkaline, and subjects all plants growing in it to extremely high mois-
ture stress (Branson et al. 1970). Areas with pure bentonite are so restrictive to plant growth
that nothing can become established. Even after heavy rains, most of the water runs off,
wetting only the top few centimeters of clay. Those areas with some plant growth appar-
ently have some organic material and silt incorporated with the bentonite or wind-
deposited from other places. As with the Artemisia tridentata/ Koeleria cristata habitat
type, this type is in an early stage of primary succession, the condition persisting due to the
inherent resistance of the material to modification. Sometimes the Atriplex-Gutierrezia
association occurs on clay outwash soils originating from raw shale slopes of the Carlile
member. These soils also are very impervious to water penetration, supporting only rela-
tively xerophytic vegetation. These sites are often adjacent to Sarcobatus bottomlands,
intergrading with the Sarcobatus vermiculatus/ Agropyron dasystachyum habitat type and
habitat types containing Artemisia.

Artemisia tridentata/ Festuca idahoensis Habitat Type
Bouteloua gracilis Phase

1. Floristic composition

Dominant — Agropyron spicatum, Festuca idahoensis

16

Subordinate — Artemisia tridentata, Stipa comata, Koeleria cristata, Artemisia frigida,
Bouteloua gracilis, Balsamorrhiza sagittata

2. Site — high elevation uplands receiving over 16 inches annual precipitation

3. Geology — Kootenai formation

4. Soil description — stony; well developed; thick, dark topsoil; loam texture; non-
saline; non-alkaline

5. Soil type — not known

6. Parent material — sandstone

7. Relative productivity — high

8. Management — withstands moderate to high grazing pressure. Highly productive
under cultivation.

Some relicts of an Artemisia tridentata-Festuca idahoensis association on the tops of
small, steep-sided buttes inaccessible to livestock are separated from the rest of the
Artemisia shrub-grasslands by approximately two miles of continuous grassland (Agro-
pyron spicatum/ Bouteloua gracilis habitat type). Artemisia tridentata is the dominant
shrub along with some Artemisia cana and Juniperus horizontalis shrubs. Agropyron
spicatum generally has a higher canopy coverage than Festuca idahoensis, although both
are dominant grasses. On these sites are some of the few occurrences of Balsamorrhiza
sagittata east of the main chain of the Rocky Mountains, although it occurs in a few other
places in the Judith Basin. This forb is an indicator of the /Artemisia tridentata-Festuca
idahoensis association in Montana and Idaho. The phase is distinguished from Dauben-
mire's (1970) Artemisia tridentata/ Festuca idahoensis habitat type in that the latter
contains no Artemisia frigida, Koeleria cristata, or Bouteloua gracilis. The presence of
Bouteloua gracilis in this phase also distinguishes it from Mueggler's and Handl's (1974)
/Artemisia tridentata/Festuca idahoensis (Montana) habitat type. This association re-
sembles Wright's and Wright's (1948) Festuca idahoensis type near Bozeman.

Rosa arkan8ana/Thermopsi8 rhombifolia Habitat Type

1. Floristic composition

Dominant — Chrysothamnus nauseosus, Artemisia tridentata, Artemisia longifolia,
Agropyron dasystachyum

Subordinate — Thermopsis rhombifolia, Arenaria hookeri, Carex parryana

2. Site — broken uplands

3. Geology — Carlile M, Belle Fourche M, Mowry M, Skull Creek M, Niobrara M (Fig. 4)

4. Soil description — thin or nonexistent, raw shale slopes, texture similar to sand, may
be saline

5. Soil type — not known

6. Parent material — marine clay shales

7. Relative productivity — low

8. Management — no particular management considerations. Cannot be cultivated.

This habitat type (found on raw, weathered clay shale) is undergoing primary succes-
sion culminating in an /Artemisia tridentata/ Agropyron dasystachyum habitat type, Agro-
pyron spicatum phase as soil is formed.

The edaphic characteristics of raw, weathered shale apparently are similar to a coarse-
grained sandy soil since the shale particles are similar in size to sand grains. With con-
tinued weathering, these will eventually be reduced to clay-sized particles, forming a clay
soil. Because of this sand-like characteristic, the floristic composition found on these raw
shale slopes resembles that occurring on sandy soils with a shrub stratum containing Rosa
arkansana, Artemisia longifolia, Artemisia tridentata, and Chrysothamnus nauseosus.

17

These shrubs are usually widely scattered, the canopy coverage of any one species rarely
exceeding 10 per cent. Canopy coverages of other taxa also are low, exposing large
amounts of bare ground. The dominant grasses (or grass-like plants) are Calamogrostis
montanensis, Agropyron dasystachyum, Carex parryana, and Calamovilfa longifolia; but
Stipa comata, well adapted to some deep, sandy soils in this region, is absent in this habitat
type. A conspicuous and ubiquitous forb throughout the habitat type is Thermopsis
rhombifolia. An occasional patch of Juniperus horizontalis and a few scattered Pinus
ponderosa trees occur on these shale slopes.

Since herbaceous plants on shale slopes in this area remain green longer during the
summer than similar plants on other upland habitat types, the suggestion is that they are
drawing on sources of moisture available to them for longer periods than is generally the
case elsewhere in the triangle. The presence of both Calamovilfa longifolia and Rosa
arkansana signifies that moisture stress in soil of this habitat type is very low (Branson et al.
1970). Cracks in the shale may allow deep penetration of both roots and water, enabling
plants to maintain themselves during long periods of drought. Since this would concen-
trate the moisture falling over a general area into a relatively few spots (the cracks), as
opposed to a soil where moisture falling over an area soaks in evenly throughout the area,
the number of plants drawing on this moisture supply and their canopy coverage would
be restricted.

In spots where the shale is weathered enough to produce a relatively deep layer of
sand-sized particles, the canopy coverage of Calamovilfa longifolia, Agropyron
dasystachyum, Thermopsis rhombifolia, and Carex parryana is greater than on less weath-
ered spots. Exposed and weathered shale-like sandstones of the Mowry member support
Calamogrostis montanensis and Carex parryana in equal proportions (canopy coverage)
and half as much Artemisia longifolia as either of the other two taxa.

A phase of this habitat type occurs on igneous intrusions and rocky outcrops such as
sandstone ledges of certain members of the Colorado formation. These outcrops support
Rhus trilobata plus a mixture of shrubs similar to that of the shale slopes. The dominant
grasses are often Agropyron spicatum or Agropyron dasystachyum. Had these sites
covered a greater area within the triangle, they may have been put into a Rhus trilobata/
Agropyron spicatum habitat type similar to the one tentatively recognized by Mueggler
and Handl (1974). Such a habitat type would be dominated by Rhus trilobata and Agro-
pyron spicatum.

Artemisia cana/ Agropyron smithii Habitat Type

1. Floristic composition

Dominant — Artemisia cana. One or the other of the grasses, Agropyron smithii or
Poa pratensis, may be dominant depending on the microhabitat.

Subordinate — Stipa viridula, Rosa ssp., Chrysothamnus viscidiflorus

2. Site — bottomlands

3. Geology — alluvium from meandering streams (Fig. 5)

4. Soil description— moderately developed. Clay loam or loam, non-saline, non-
alkaline, high water table, well drained

5. Soil type — not known

6. Parent materials — alluvial silt

7. Relative productivity — high

8. Management— heavy winter grazing pressure is destructive of pronghorn winter
habitat.

Although a few scattered bushes of Artemisia cana grow on some of the uplands
(usually on the Kootenai formation) of the triangle, the species is normally restricted to
apparent high water deposits and old stream channels along major streams (Hanson and
Whitman 1938, Beetle 1960) where soil is coarser (Branson et al. 1970).

The perennial grass layer usually comprises one or more of the following species:

18

Agropyron smithii, Stipa viridula, or Poa pratensis. Poa pratensis is an invader species
establishing in certain moist areas, probably as a result of some trigger factor or factors
such as overgrazing or flooding. Forb species number and cover are generally small with
various taxa scattered throughout the type.

The distribution of Artemisia cana in the triangle resembles what Thatcher (1959)
observed in southeastern Wyoming. He determined that the shrub is usually found on
lowlands with the water table often within the root zone, and on moderately deep, slightly
to moderately alkaline soils that are permeable in all horizons. Whenever the shrub
occurs on uplands in southeastern Wyoming and in the triangle, the soil parent materials
are sandstone or gravel.

Sorcobatus Series
Sarcobatus vermiculatus /Agropyron dasystachyum Habitat Type

1. Floristic composition

Dominant — Sarcobatus vermiculatus, Poa sandbergii, Agropyron dasystachyum. The
following may be dominant dependent on microhabitat: Artemisia tridentata,
Bouteloua gracilis, Distichlis stricta

Subordinate — Agropyron smithii, Koeleria cristata, Artemisia frigida, Carex steno-
phylla, Opuntia polyacantha

2. Site — bottomlands

3. Geology — alluvium from marine shales (Fig. 6)

4. Soil description — silty or clay loam, well developed where not eroded, alkaline
ground water near surface, poorly drained, saline and alkaline, light colored

5. Soil types — Absher, Nobe, Billings-Arvada

6. Parent materials — alluvium

7. Relative productivity — low to moderate

8. Management — will withstand moderate grazing. Conversion to hayfields is success-
ful with irrigation.

The purest stands of Sarcobatus are in bottomland areas of the triangle where allu-
vium derived from Colorado formation shales has been deposited. However, pure stands
of Sarcobatus are not common; usually some Artemisia is present. As one travels away
from a stream, bordered mainly by shrubs such as Symphoricarpus and Rosa, a band of
Artemisia cana is usually encountered and then a band of pure Sarcobatus or Sarcobatus
and Chrysothamnus nauseosus mixed. Traveling still farther from the stream, Artemisia
tridentata bushes are seen, the coverage increasing progressively until pure Artemisia-
grass stands are reached. The grass layer in the Sarcobatus vermiculatus/ Agropyron
dasystachyum habitat type is a mosaic with different sites dominated by Agropyron
dasystachyum or Agropyron smithii and Poa sandbergii or by Distichlis stricta. Various
intergradations are involved. This is similar to Mueggler's and Handl's (1974) Sarcobatus
vermiculatus/ Agropyron smithii habitat type except that their grass layer has large
amounts of Agropyron smithii rather than Agropyron dasystachyum as is the case in most
areas here.

Hanson and Whitman (1938) do not report a Sarcobatus type in western North Dakota
although the species does occur there in very minor amounts. They do report Distichlis-
Agropyron smithii and Artemisia cana types; Sarcobatus apparently has not become
extensively established in those areas, although the habitat seems favorable.

Juniperu8 Series

Juniperus horizontalis/Carex parryana Habitat Type

1. Floristic composition

19

Dominant — Carex parryana, juniperus horizontals, Calamogrostis montanensis
Subordinate — Thermopsis rhombifolia, Eriogonum pauciflorum, Carex stenophylla

2. Site — hilly uplands

3. Geology— restricted to the unnamed sandy M (Fig. 7)

4. Soil description — same as for Artemisia/Chrysothamnus nauseosus habitat type

5. Soil type — not known

6. Parent material — sandy shale

7. Relative productivity — low

8. Management — no particular management considerations. Cannot be cultivated.

This habitat type is visually conspicuous and distinctive in appearance. As primary
succession advances, this becomes an Artemisia/ Agropyron habitat type as judged from
data gathered on shale where soil had formed. Also found on this outcrop is a stand of
Pinus ponderosa with juniperus horizontals and Agropyron spicatum in the understory.
It is unclear whether this is another stage of primary succession or if there is some inher-
ent edaphic difference causing the establishment of Pinus.

Wetlands

Riparian Series

Populus deltoides/ Symphoricarpus occidentalis Habitat Type

1. Floristic composition

Dominant — (depending on microhabitat) Populus deltoides, Symphoricarpus
occidentalis, Rosa woodsii, Prunus virginiana, Salix amydaloides, Salix rigida, Acer
negundo

Subordinate — Ribes ssp., Shepherdia argentea, Poa pratensis, Agropyron smithii,
numerous forbs

2. Site — riparian

3. Geology — next to streams (Fig. 8)

4. Soil description — silty, high water table, non-saline, non-alkaline, subjectto flooding

5. Soil type — not known

6. Parent material — alluvium

7. Relative productivity — very high

8. Management — heavy livestock use is destructive of mule deer and white-tailed deer
habitat.

This type occurs along streams which flow during a considerable portion of the grow-
ing season. Taxa of the habitat type require large amounts of moisture, obtained from
water migrating out from the stream. Two phases are recognized within the habitat type
depending upon whether or not trees are present.

The Populus deltoides-Symphoricarpus occidentalis association comprises a variable
mixture of Populus deltoides, Acer negundo, Salix amygdaloides, Prunus virginiana,
Crataegus douglasii (mostly on the west side of the triangle), Symphoricarpus occiden-
talis, Rosa woodsii, plus some Ribes ssp., Sa//x rigida, and Shepherdia argentea. The
Symphoricarpus occidentalis-Rosa woodsii association is similar except for an absence of
trees. A quantitative sampling of this habitat type was not attempted becausethe distribu-
tion of various species was extremely variable and appeared largely due to chance. Some
basic differences may exist in the habitat type as it occurs on the west or the east side of the
triangle, possibly due to greater and more dependable water supply in the streams farther

20

west. Salix rigida and /nter/or primarily grow next to continuously running streams such as
Flatwillow Creek. Many species of mesomorphic forbs, including Arctium lappa,
Asclepias speciosa, Bidens vulgata, Cicuta douglasii, Clycyrrhiza lepidota, Helianthella
uniflora, Rumex ssp., Solidago gigantea, Urtica dioica, and others, occur throughout the
habitat type.

Scirpus /Carex Habitat Type

1. Floristic composition

Dominant — Scirpus americanus, Schedonnardus paniculatus, Scirpus validus, Carex
rostrata, Carex nebraskensis

Subordinate — juncus balticus, Beckmannia syzigachne, Spartina gracilis

2. Site — streamsides, alongside reservoirs

3. Geology — alluvium

4. Soil description — constantly wet, anaerobic, high organic matter content, non-saline,
non-alkaline

5. Soil type — not known

6. Parent material — alluvial silt

7. Relative productivity — very high

8. Management — Livestock grazing of these areas is highly destructive to waterfowl
habitat.

This habitat type occurs on only a few acres of the triangle, usually in marshy areas
along some slow-moving streams and around reservoirs. Dominant vegetation comprises
Scirpus americanus, S. paludosus, S. validus, Juncus balticus, Typha latiiolia, Carex
rostrata, C. nebraskensis, plus smaller amounts of Beckmannia syzigachne and Spartina
gracilis. Water movement and exchange is rapid enough to prevent a build-up of salts.

Suaeda/ Salicornia rubra Habitat Type

1. Floristic composition

Dominant — Suaeda fruticosa, Suaeda occidentalis, Salicornia rubra, Puccinellia
nuttalliana

2. Site — swales, bottomlands, saline seeps

3. Geology — Niobrara M, Belle Fourche M, unnamed sandy M, Skull Creek M, alluvial
terraces and bottomlands

4. Soil description — wet, extremely saline and alkaline, clay texture, anaerobic

5. Soil type — not known

6. Parent material — marine shales, alluvium

7. Relative productivity — low

8. Management — Management considerations may involve only the prevention of the
increase of such areas.

This very minor habitat type occurs where extremely saline and alkaline water seeps
continuously and slowly at the surface. Water movement is slow enough that it evaporates
and becomes saturated with salts (usually sodium and magnesium sulfates), forming white
crusts on the ground surface and on objects protruding out of the water. A few extreme
halophytes (plants adapted to saline conditions) can exist, but even though water is always
present, non-halophytes are subjected to severe physiological drought and cannot
become established. The vegetation association is dominated by Suaeda fruticosa, S. occi-
dentalis, Salicornia rubra, and sometimes Puccinellia nuttalliana.

21

^JUPPER COLORADO F.

] ALLUVIUM
7^] TERRACES

Figure 3. Distribution of the Artemisia tridentata/Agropyron spicatun
Habitat Type, Bouteloua Phase.

^]UPPER COLORADO F

] ALLUVIUM
77] TERRACES

Figure 4. Distribution of the Artemisia tridentata/Agropyron
dasystachyum Habitat Type, Agropyron spicatum and
Sarcobatus vermiculatus Phases and the Rosa
arkansana/Thermopsis rhombifolia Habitat Type.

^JUPPER COLORADO F.

] ALLUVIUM
TJr\ TERRACES

Figure 5. Distribution of the Artemisia cana/ Agropyron smithii Habitat
Type.

22

PPER COLORADO F.
ALLUVIUM

Figure 6. Distribution of the Sarcobatus vermiculatus/Agropyron
dasystachyum Habitat Type.

E3
El
□

|ELLIS

KOOTENAI F *
LOWER SANOSTONE M
UNNAMEO SANDSTONE M
♦ SKULL CREEK M

BELLE FOUflCHE M

MOWRY M

i~HuPPER COLORADO F

| ALLUVIUM
?~] TERRACES

Figure 7. Distribution of the Juniperus horizontalis/Carex parryana
Habitat Type.

□

KOOTEN

LOWER SANDSTONE M
UNNAMED SANDSTONE M
CREE

~"]uPPER COLORADO F.

| ALLUVIUM
7/\ TERRACES

Figure 8. Distribution of the Populus deltoides/Symphoricarpus
occidentalis Habitat Type.

23

una

on
□

EZ3

3 quadrant
Ielus f

KOOTENAI t
LOWER SANDSTONE M
UNNAMED SANDSTONE
♦ SKULL CREEK h
BELLE FOURCHE

^JUPPER COLORADO F

1 ALLUVIUM
^TERRACES

lFigure9. Distribution of the Agropyron spicatum/Agropyron smithii
Habitat Type and the Muhlenbergia cuspidata/Andropogon
scoparius Habitat Type.

L :::i lower sanostone m

rrTTTq UNNAMED SANDSTONE
l"--4+ SKULL CREEK M

□BELLE FOURCHE
MOW

^]uPPER COLORADO F

J ALLUVIUM
77] TERRACES

Figure 10. Distribution of the Pinus ponderosa/ Artemisia tridentata
Habitat Type.

□'

(•"""•IKOOTE

I; :: :i lower sandstone m

prTTTl UNNAMED SANDSTONE

SKULL CREEK M
FOURCHE

^juPPER COLORADO F

| ALLUVIUM
^TERRACES

Figure 11. Distribution of the Pinus ponderosa/Agropyron spicatum
Habitat Type.

24

Artemisia tridentata/Agropyron spicatu
Habitat Type
Bouteloua gracilis Phase

Artemisia tridentata/Agropyron spicatum
Habitat Type
Agropyron smithii Phase

Artemisia tridentata/Agropyron dasystach

Habitat Type,

Agropyron spicatum Phase

Artemisia tridentata/Koeleria cristata
Habitat Type

Atriplex dioica/Gutierrezia sarothrae
Habitat Type

Artemisia tridentata/Festuca idahoensis
Habitat Type
Bouteloua gracilis Phase

Artemisia tridentata/ Agropyron
dasystachyum Habitat Type,
Sarcobatus vermiculatus Phase

wk

Sarcobatus vermiculatus/ Agropyron
dasystachyum Habitat Type

Artemisia cana/Agropyron smithii
Habitat Type

Populus deltoides/Symphoricarpus
occidentalis Habitat Type

jgp».«i*a?*

H I I '' ■

t- :;*

Scirpus/Carex Habitat Type

Suaeda/Salicornia rubra Habitat Type

i Rosa arkansana/Thermopsis rhombifolia

*5f? Habitat Type

juniperus horizontalis/Carex parryana
Habitat Type

Agropyron spicatum/Agropyron
smithii Habitat Type

Poa pratensis/Artemisia ludoviciana
Habitat Type

Muhlenbergia cuspidata/Andropogon
scoparius Habitat Type

Pinus ponderosa/ Artemisia tridentata
Habitat Type

Pinus ponderosa/Agropyron spicatum
Habitat Type

29

Grasslands

On the Lower Sandstone member of the Colorado shale formation, the Kootenai
formation and the Ellis formation are vegetation associations consisting of grasslands vir-
tually devoid of shrubs. One sample plot contained some Chrysothamnus viscidiflorus
and was the only one with any shrub cover. Noted in various areas, but not occurring in
any sample plots, were scattered bushes of Artemisia tridentata, Artemisia cana, juniperus
horizontalis, and Rosa woodsii. A possible explanation for this paucity of shrubs is a
shallow solum above impermeable bedrock. Shrubs are more common on strike slopes
(the steep, broken part of a rock outcrop) (Rhus trilobata-Agropyron spicatum phase),
and in low spots where soil has been washed in from adjacent areas and deposited.
Apparently, areas of the Kootenai formation receiving over approximately 17 inches in
annual precipitation support Pinus ponderosa forests rather than grasslands as climax.
Comparisons between photographs made in 1917 by H. L. Shantz.andof exactly the same
sites in 1959 by Philips (Philips 1963), show substantial increases in Pinus cover on the
Kootenai formation at the expense of the open grassland. Pinus may advance into the
grassland during favorable seedling establishment years as a result of disturbances
("Trigger factors," Billings 1952) such as overgrazing, or it may be that grasslands were at
one time maintained by fire and with the advent of fire protection, the Pinus is advancing
(Griggs 1938).

Agropyron spicatum/ Agropyron smithii Habitat Type

1. Floristic composition

Dominant — Agropyron spicatum, Stipa comata, Artemisia frigida

Subordinate — Agropyron smithii, Bouteloua gracilis, Calamovilfa longifolia, Koeleria
cristata, Poa sandbergii, Cerastium beeringianum, Vicia americana, Carex parryana

2. Site — undulating uplands

3. Geology — Kootenai formation, Lower Sandstone M, Ellis formation (Fig. 9)

4. Soil description — well developed, brown or red topsoils, loam texture, non-saline,
non-alkaline, well drained, subsoil non-clayey, stony, often shallow solums

5. Soil types — Castner-Morton loams and stony loams, Cushman loam, Darrett loam
and stony loam

6. Parent material — sandstone

7. Relative productivity — high

8. Management — withstands moderate grazing, highly suitable for cultivation.

This habitat type appears virtually identical to the one described by Mueggler and
Handl (1974) and will be given the same name as theirs to maintain synonymy. Of the
grassland types, the Agropyron spicatum/ Agropyron smithii habitat type covers the
greatest area, although a considerable amount of it has been planted tograin and crested
wheatgrass. The bedrock is partly weathered, metamorphosed sandstone, relatively im-
pervious to roots or water. Because of the shallow solum and impermeability of the
bedrock, the soils are considered to have low water-holding capacity (Gieseker 1953). A
lithosolic phase of this habitat type where Stipa comata has greater coverage than
Agropyron spicatum because of edaphic rather than grazing reasons is recognized.
Depending on characteristics of individual microhabitats, plus differences in grazing
pressure, either Agropyron smithii, Stipa comata, or Calamovilfa longifolia is the domi-
nant grass. Considering the habitat type as a whole (in its current grazed condition), Stipa
comata has the greatest canopy coverage, followed by Agropyron spicatum. Another
important mid-grass is Agropyron smithii. The short grasses, Koeleria cristata and Poa
sandbergii, are about equal in abundance.

Total canopy coverage and number of forb species are much higher on grassland
habitat types than on any of the other habitat types in the triangle. Artemisia frigida and
Cerastium beeringianum are the most common forbs, although numerous others are
abundant. Some forbs common in this association, but completely absent in the shrub-

30

dominated associations, are Heuchera parviflora, Artemisia biennis, Helianthus petiolaris,
Gerastium beeringianum, Hymenopappus filifolius, and Phlox kelseyi.

Muhlenbergia cuspidata/ Andropogon scoparius Habitat Type

1. Floristic composition

Dominant — Muhlenbergia cuspidata, Andropogon scoparius

Subordinate — Agropyron spicatum, Agropyron dasystachyum, Koeleria cristata,
Stipa comata, Stipa viridula, Gutierrezia sarothrae, Phlox hoodii, Linum perenne,
Aristida longiseta

2. Site — moderately steep slopes in uplands

3. Geology — Kootenai formation (Fig. 9)

4. Soil description — weak development, red color, loam texture, non-saline, non-
alkaline, well drained, eroded

5. Soil types — Darrett loam and stony loam

6. Parent material — red shale

7. Relative productivity — moderate

8. Management — Light grazing, not suitable for cultivation.

The Muhlenbergia cuspidata-Andropogon scoparius association is apparently re-
stricted to a particular stratum of shaly or silty parent material in the Kootenai formation.
This is the only place in the triangle where either of these grasses occurs as dominants.
Andropogon is an important component of true prairie grasslands in the Midwest
(Weaver and Fitzpatrick 1934) and gradually increases in abundance when approaching
that region. In south central South Dakota, White (1971) determined that both Andro-
pogon scoparius and Muhlenbergia cuspidata were most abundant on weakly developed
soils subject to rapid erosion. Observations indicate that this is also the case in the triangle
and in other parts of eastern Montana. The Judith Basin to the west of the triangle prob-
ably represents the westernmost occurrence of this species at this latitude. If one follows
Dix's (1958) moisture ordination with Bouteloua gracilis and Agropyron smithii on the dry
end, and Andropogon and Muhlenbergia on the wet end, it might be concluded that this
vegetation association occurs on a more moist site than most of the other upland asso-
ciations. Other important grasses are Agropyron spicatum and Aristida longiseta.
Although stands of Pinus often occupy similar sites, it is unclear whether the presence of
these trees represents different environmental conditions or merely vagaries of distribu-
tion. Juniperus horizontalis is important locally but not over the general area of the habitat
type. There is a relatively large number of forb species present (more than any other
habitat type in the triangle) but none of them is important in terms of canopy coverage
except Gutierrezia sarothrae (also considered a half-shrub). Plant and litter coverage are
much less in this habitat type than in the other grassland habitat types.

Poa pratensis /Artemisia ludoviciana Habitat Type

1. Floristic composition

Dominant — Poa pratensis, Agropyron smithii, Artemisia ludoviciana

Subordinate — Melilotus officinale, Cirsium undulatum, juncus balticus, Carex
rostrata, Garex foenea, Achillea millefolium

2. Site — swales

3. Geology — Kootenai formation

4. Soil description — deep topsoil with abundant organic matter, loam texture, non-
saline, non-alkaline

5. Soil type — not known
31

6. Parent material — sandstone and alluvium

7. Relative productivity — very high

8. Management — can withstand moderate grazing pressure. Cannot be cultivated.

Swales in the grassland habitat types support a more mesophytic vegetation associa-
tion than the swales in the eastern part of the triangle. The Poa pratensis- Artemisia ludo-
viciana association contains the second greatest number of species and the most complete
plant cover of any in the triangle. Canopy coverage of both grasses and forbs is much
higher than in any of the other habitat types. Other important grasses are Agropyron
smithii and Agropyron repens. Since two out of three of the dominant grasses are in-
vaders, there is a question as to the dominant grass composition before the onset of
disturbance by overgrazing. It is expected that dominance of this plant community by
non-native grasses will continue regardless of any changes in management, justifying the
consideration of this as a habitat type. Other forbs occurring in considerable quantities
are Achillea millefolium (invader), Melilotus officinale (invader), and Cirsium undulatum.
Sedges and rushes include Carex foenea, C. rostrata, and juncus balticus. These swales are
surrounded by very large, flat, sloping tables covered with soils of low moisture-holding
capacity releasing considerable quantities of water to migrate gradually into the swales
during much of the growing season. This favors the establishment of some hydrophytes
(i.e., Typha latifolia, Juncus balticus).

Coniferous Forest

Pinus Series
Pinus ponderosa/ Artemisia tridentata Habitat Type

1. Floristic composition

Dominant — Pinus ponderosa, Artemisia tridentata

Subordinate — juniperus horizontalis, Agropyron spicatum, Aristida longiseta, Poa
sandbergii

2. Site — steep shale slopes

3. Geology — Mosby M, unnamed sandy M (Fig. 10)

4. Soil description — thin or undeveloped, raw shale slopes, texture similar to sand

5. Soil type — not known

6. Parent material — sandy shales, soft sandstone

7. Relative productivity — low

8. Management — Leave as is for mule deer cover. Timber not commercially important.

This habitat type occurs on various exposed strata of the Colorado shale formation
because of some unknown favorable combination of edaphic and topographic factors.
While reproduction of pine is evident, indicating that the populations are probably main-
taining themselves, it is difficult to determine whether or not they are increasing in area.
The density of the stands ranged from about 20-28 trees per acre, with all sizes repre-
sented. The diameter breast height (dbh) of mature trees is generally less than 10 inches.
The understory of the association comprises mainly the shrubs Artemisia tridentata and
Juniperus horizontalis and the grass /Agropyron dasystachyum; Agropyron spicatum is
locally important. Bare ground (disregarding the canopy coverage of the trees) occupies a
relatively great area, although not as much as in some other habitat types.

Pinus ponderosa/ Agropyron spicatum Habitat Type

1. Floristic composition

Dominant — Pinus ponderosa, Agropyron spicatum
Subordinate — Balsamorrhiza sagittata

32

2. Site — high elevation uplands, estimated annual precipitation 17 inches

3. Geology — Kootenai formation, Ellis formation, Quadrant formation (Fig. 11)

4. Soil description — well developed, brown or red topsoils, loam or sandy loam texture,
non-saline, non-alkaline, well drained, subsoil not clayey, stony, often shallow
solums

5. Soil types — Castner-Morton loams, Cushman loam, Darrett loam and stony loam

6. Parent material — sandstone

7. Relative productivity — high

8. Management — not suitable for commercial timber production. Provides habitat for
mule deer if not overgrazed.

Pine stands of this type generally have an understory of similar floristic composition
and less canopy coverage than adjoining grasslands. There are about 15-20 trees per acre
in mature stands and up to three times this many in stands of young trees. Apparently, two
important age classes (as judged from aerial photographs) are represented, indicatingthat
seedlings become established only during certain periods (lasting probably two or more
consecutive years) when favorable conditions exist for heavy seed production, seed
germination, seedling survival, and development of seedlings into young, relatively
drought-resistant trees. This probably applies also to some other seed-reproducing
species such as Artemisia tridentata and Agropyron spicatum, which in this region appear
to be near the edge of their range. A large increase in the density of Pinus stands in this
general area (western triangle and west) occurred between 1917 and 1959, as shown by
photographs of Shantz and Philips (1963).

This type is considered synonymous to the Pinus ponder osa/ Agropyron spicatum
habitat type of Pf ister, Arno et al. (1977) and so is given the same name. A few small stands
of Pinus ponderosa with Symphoricarpus occidentalis in the understory were noted, indi-
cating the presence of a Pinus ponderosa/Symphoricarpus occidentalis habitat type
(Pfister, Arno et al. 1977) within the triangle, although in very minimal amounts. Some
Pseudotsuga menziesii trees were also seen on a steep, north-facing slope in the western
part of the triangle, but were not considered abundant enough to constitute a stand of
Pseudotsuga menziesii habitat type.

Distribution of Important Taxa

Artemisia tridentata

Beetle (1960) considers central Montana to be at the northeastern edge of /Artemisia
tridentata distribution. The A. tridentata in the triangle fits the characteristics of sub-
species wyomingensis as described by Beetle and Young (1966). Some A. tridentata occurs
in eastern Montana, but farther east it apparently becomes increasingly confined to areas
of moisture collection, deep soil, and good drainage (i.e., swales).

Artemisia covers a greater percentage of the land in the triangle (Appendix A Table 1)
than any other shrub; considerations of its distribution are very important when ana-
lyzing the vegetation of the area.

The distribution pattern of Artemisia apparently results from a combination of natural
and man-caused factors. Numerous workers have reported that Artemisia increases both
in density and range following heavy livestock grazing (Wright and Wright 1948, Pickford
1932, Cottam and Stewart 1940, Shantz and Piemeisel 1940, Tisdale 1947, Thatcher 1959,
Johnson 1966, and Pearson 1965). In undisturbed plant communities containing Arte-
misia, the Artemisia is in a state of dynamic equilibrium with dominant grasses (usually tall
bunchgrasses) in the community. Neither of these has a complete competitive advantage
over the other and so the importance of the Artemisia remains the same. However, when a
disturbing factor is inserted, one dominant increases in importance. Heavy livestock use
increases the competitive advantage of Artemisia over most tall grasses, often resulting in
greater cover, density, and range of the shrub. Reconstructing the relative importance of
Artemisia before the arrival of domestic livestock is very difficult since there are no his-

33

torical records of this sort, and completely relict areas on Artemisia habitat types are rare.
Other land treatment practices, such as plowing and seeding, are also important in
changing the density and distribution of Artemisia. After certain land treatment practices
cease (as they have in many cases), the density and distribution of Artemisia may remain
unchanged for many years.

Natural soil factors also affect the distribution and vigor of Artemisia. Evidence pre-
sented in the literature concerning the effects of soil on Artemisia apparently is some-
what conflicting. However, it must be considered that the various studies were conducted
in widely differing climatic and geographical areas with different subspecies and ecotypes
of the species. It is generally agreed that Artemisia grows best on deep soils (Beetle 1960,
Fautin 1946, and Thatcher 1959). Fautin (1946) found that Artemisia in western Utah was
most abundant on relatively non-saline, permeable soils with high water-holding capa-
city. According to Patten (1963), Artemisia in southwestern Montana grows best on sandy
loam soils, and Robertson et al. (1966) found that soils with sandy loam to loam topsoils
were best. However, Houston (1961) determined that Artemisia in the northern Great
Plains was most abundant in clayey soils. Thatcher (1959) and Gates (1956) agreed with
Fautin (1946) that Artemisia is favored by soils of low salt content. Smith (1966) found pH
ranges of 6.5 to 7.5 (very slightly acid to very slightly alkaline) in the topsoil and 7.5 to 8.5
(very slightly alkaline to alkaline) in the subsoil to be favorable for Artemisia in North Park,
Colorado. Thatcher (1959) found that Artemisia in southeastern Wyoming grew on soils
derived from almost every conceivable type of parent material, but that it could not
tolerate high water tables or fine-textured subsoils. Data from Brown (1971) indicated that
Artemisia in southwestern Montana is most abundant on clay loam and silt loam soils with
relatively low salinity and sodium content and relatively high calcium to sodium ratios. In
considering what appear to be conflicting results as reported above, it must be kept in
mind that all three different subspecies (and different ecotypes within those subspecies)
were involved in those studies. For example, observations indicate that A. tridentata ssp.
tridentata is better able to tolerate sandy soils (or the competition of other plants thereon)
than is A. tridentata spp. wyom/ngens/s.

Observations in the triangle indicate that A. tridentata ssp. wyom/'ngens/'s is most
vigorous on soils with a clay loam topsoil. It is less vigorous on gravelly soils and calcareous
silty soils and it is virtually nonexistent on soils derived from Kootenai sandstones. Low-
lying areas with poor drainage and high salt content support little or no Artemisia.
Artemisia is a minor constituent of the vegetation communities on raw shale slopes and
rocky areas. Very sandy soils derived from the Eagle sandstone just east of the triangle are
totally devoid of A. tridentata, but support some A. cana. Because of fire, some sites in the
eastern part of the triangle are devoid of Artemisia; after 30 or 40 years, Artemisia has not
re-established itself in these areas.

For reasons discussed above, no attempt will be made to describe the relative abun-
dance of Artemisia in various habitat types except in some cases where edaphic condi-
tions definitely appear to be a factor. While not supported by data, all areas in the triangle
which now have Artemisia were probably historically occupied by the shrub, although
possibly in greater quantity now. A large upland area in the western part of the triangle
surrounding Button Butte is virtually free of Artemisia, apparently due to edaphic condi-
tions.

Agropyron spicatum

Ecologically, Agropyron spicatum appears to be the most important grass in the
triangle. It is usually found on soils exhibiting considerable profile development, in-
cluding the presence of a well-defined mollic epipedon (a friable topsoil containing
considerable dark-colored organic matter), plus a distinct subsoil horizon. Such soils
generally range in texture from clay loam to loam, although the species is not entirely
restricted to these. Good soil drainage and root penetration are necessary. A. spicatum is
found on slightly vertic soils in some parts of the triangle. General observations indicate
that this may bean unusual situation and that some compensating factor must be present,
because A. spicatum roots are not resistant to breakage produced by cracking and
heaving in such soils. Possibly, although it was not determined, the vertic soils with good
stands of A. spicatum are very shallow with some sort of permeable material beneath, such

34

as heavily fractured weathered shale. All sites where A. spicatum occurred on vertic soils
were found on shale strata of the unnamed sandy member in the Colorado shale forma-
tion and on the Bearpaw shale formation north of the triangle. More study is needed in
other locations to determine the relationship of A. spicatum to vertic soils.

A. spicatum is not found on most soils lacking a distinct topsoil, on saline or alkaline
soils, on poorly drained soils, on bentonitic soils, or on calcareous silty soils. Small
amounts occur on stony, shallow soils with fractured bedrock and on raw shale slopes.
Daubenmire (1970) notes that within the climatic zone where A. spicatum is a major domi-
nant, very thin soil over fractured basalt supports vigorous stands of this species. Brown
(1971) noted that A. spicatum is most abundant (with Artemisia tridentata) on soils
possessing moderate characteristics. Salinity and alkalinity were low, slope was moderate,
texture was a clay loam, and horizon development was evident. In southwestern North
Dakota, Dodd (1970) found A. spicatum to be restricted to extremely rocky infertile soils
on the tops of hills.

A. spicatum occurs with various different dominant or subdominant species depend-
ing on the habitat type. On Colorado shale areas, it is co-dominant with Artemisia triden-
tata; Bouteloua gracilis, Koeleria cristata, and Stipa comata are other important grasses in
the association. On the Kootenai formation, it is co-dominant with Stipa comata, Agro-
pyron smithii, and Artemisia frigida, all of which, with the possible exception of Stipa, are
increasers with grazing and may not be as abundant in the habitat type as the data indicate.
A. spicatum is also co-dominant with Artemisia tridentata and Festuca idahoensis in the
Artemisia tridentata /Festuca idahoensis habitat type. In other parts of Montana, and in
Idaho and Washington, such an association may represent a transition between the
Artemisia tridentata/ Agropyron spicatum habitat type (Festuca absent) and the Artemisia
tridentata/ Festuca idahoensis habitat type {Agropyron spicatum absent) (Wright and
Wright 1948, Daubenmire 1970).

Agropyron smithii

This grass has very wide ecologic amplitude, tolerating a wide range of soil moisture
stress situations (Branson et al. 1970); it is found in at least small amounts in most habitat
types of the triangle. It apparently is most abundant in moist swales (Holscher 1945) and
bottomlands where drainage is good. It often is also an important constituent of the
Artemisia tridentata/ Agropyron dasystachyum habitat type, Agropyron spicatum phase
(Rosset al. 1973). Although A. smith// appears capable of withstanding considerable levels
of soil salinity, it is usually not dominant in highly saline areas. Agropyron can survive in
some soils with extremely high clay content but it is more vigorous and abundant on
medium (loam or clay loam) textured soils such as those found in swales, presumably be-
cause of better root penetration (Jorgensen 1970). Soil conditions on many other sites are
probably favorable for A. smithii, but it is not found in great abundance on these sites due
to competition from other grasses. Soil disturbances of such sites, detrimental to many of
the species normally dominant there, allow establishment of A. smithii with its aggressive
colonization capabilities (Judd 1937). Data from Ross et al. (1973) show A. smithii to be
dominant on silty range sites in northern and northeastern Montana, on clayey range sites
throughout the state, and occurring in only minor amounts on most other range sites.
White (1971) determined that Agropyron in south central South Dakota was most
common on well developed soils, but was also important on some poorly developed soils
if they were fine-textured.

Stipa comata

In the triangle, Stipa comata has the greatest canopy coverage and frequency in habi-
tat types dominated by Artemisia tridentata and/or Agropyron spicatum. Generally, it
occurs where Agropyron spicatum would be dominant under undisturbed conditions,
even though this dominance may not exist now.

Stipa is a habitat type dominant where soils are sandy (White 1971). Soils derived from
Eagle sandstone (east of the triangle across Route 244) are very sandy and support much
more vigorous stands of Stipa than any within the triangle. Ross et al. (1973) present data
supporting this conclusion. S. comata does not occur in the triangle (or other areas,
Coupland 1961) on soils of finer texture than clay loams, increasing in importance with

35

increasing coarseness of soil texture (from clay loam to loam). Data of Ross et al. (1973)
indicate that S. comata is absent on clayey range sites and is a dominant on silty range sites.
Data from the triangle do not seem to agree with Ross et al. that 5. comata is a dominant on
silty range sites although this may result from the fact that their silty range sites are some-
what different climatically and are not as calcareous as those in the triangle.

Stipa viridula

Stipa viridula occasionally occurs as a dominant in association with rhizomatous
wheatgrasses and Artemisia cana. Very rarely do heavy stands of this grass occur in the
triangle, although it is found in small quantities in numerous areas. Coupland (1961) found
that S. viridula was important in communities dominated by Agropyron dasystachyum and
Koeleria cristata.

Site characteristics favorable for the species seem to be similar to those for Agropyron
smithii because of its strong association with Agropyron smithii. Because it is most abun-
dant in swales and /Artemis/a cana bottomlands, the most favorable site apparently is one
with deep moisture penetration and a medium-textured soil. Although it is most abun-
dant on medium-textured soils, it is also well-adapted to very fine-textured, vertic clay
soils (White 1971). Data from Ross et al. (1973) agree with those from the triangle showing
that Stipa may be more of a dominant in clayey triangle habitat types than data seem to
show since there is evidence that Stipa is a decreaser under grazing (Ross et al. 1973,
Hanson et al. 1931) and most of these areas have experienced heavy grazing pressure.

Habitat types with clay loam or gravelly clay loam topsoils and clay subsoils (gravel-
capped tables) do not support significant amounts of S. viridula but it has often been
noted that where sites within these habitat types were plowed and abandoned, S. viridula
increased in abundance. This may result from possible increased clay content of the upper
soil due to mixing of the A and B horizons, or a possible aggressiveness of the grass in
establishing on disturbed areas. Thatcher (1966) has a different explanation for this. He
concluded that disc-plowing of shortgrass prairies (a disclimax dominated by Boute/oua
gracilis, Buchloe dactyloides, and Carex stenophylla) causes a return to a more climax
situation where midgrasses dominate. These midgrasses include Agropyron smithii 'and S.
viridula and possibly S. comata. S. viridula is also abundant in other disturbed areas such as
abandoned irrigation ditches, roadsides, and crested wheatgrass seedings.

Bouteloua gracilis

Bouteloua is an important grass in the Artemisia tridentata/ Agropyron spicatum
habitat type (Bouteloua phase) and the Sarcobatus vermiculalus/Agropyron
dasystachyum habitat type in the triangle. Data from Brown (1971) show that Boute/oua is
most important in his Sarcobatus and Artemisia tridentata- Agropyron spicatum commu-
nities. Most studies indicate that it increases with grazing pressure and can therefore be
considered to be more abundant at the presenttimethan before the arrival of livestock. It
is most abundant on the gravel-capped tables and Sarcobatus-dominated bottomlands
where topsoil is remaining. Bouteloua is usually found as a subordinate grass in
Agropyron spi'catum-dominated habitat types, and may or may not be found with Arte-
misia tridentata.

Bouteloua is most highly adapted to well-developed, medium-textured soils (clay
loams to loams) although one study indicated that it was more vigorous on sandy soil than
on loam (Mueller 1941). The root system is shallow, allowing it to make maximum use of
moisture from light showers (Weaver 1958). In the triangle, summer showers frequently
wet only the topsoil (if present), giving Bouteloua a competitive advantage over many
other plants since it is highly adapted to use this moisture. Bouteloua is not found on
weakly developed soils with clay at the surface, presumably because such soils are dry at
shallow depths for too long (Coupland 1961). Plowing a soil with a clay subsoil virtually
eliminates Bouteloua from the site for many years, possibly due to the increase in clay at
the surface. Bouteloua has a narrow range of moisture stress tolerance, being unable to
withstand either extremely high moisture stress (as in heavy clay soils) or extremely low
moisture stress (as in poorly drained situations) (Branson et al. 1970). This may offer addi-
tional explanation as to why Boute/oua is not found on heavy clay soils. Bouteloua may
occur on well-developed solonetzic soils such as on certain bottomlands occupied by
Sarcobatus (Coupland 1961).

36

Koeleria cristata

Koeleria is most abundant in the Artemisia tridentata/ Agropyron spicatum (Boute-
loua phase), Agropyron spicatum/Bouteloua gracilis, Sarcobatus vermiculatus/Agro-
pyron dasystachyum, and Artemisia tridentata/ Koeleria cristata habitat types. In only the
latter can it be considered a dominant constituent of the plant community, possibly
because it is favored by the silty, calcareous soil of that habitat type. The canopy coverages
of Koeleria in the habitat types where it is abundant are almost identical, so the degree of
its importance in different habitat types results from the variability of abundance of other
taxa in the plant communities.

Wright and Wright (1948) found that Koeleria was most abundant in their vegetation
type with the most Agropyron spicatum, and was a co-dominant with Stipa comata and
Bouteloua gracilis in another vegetation type. Koeleria always occurred in communities
with more than trace amounts of Agropyron spicatum.

Others working in mixed prairie grasslands (Ellison 1960, Hanson and Whitman 1938,
Coupland 1961, Mackie 1970, and Smith 1969) agree that Koeleria is strongly associated,
and is often a co-dominant, with rhizomatous wheatgrasses such as Agropyron dasys-
tachyum and Agropyron smithii. Koeleria occasionally co-dominates with Bouteloua
gracilis but more often it seems to be a subordinate grass in associations dominated by this
species. Although this species possesses a high ecologic amplitude, it is absent in the
triangle in extremely heavy clay soils, moist swales, saline and/or alkaline soils, Pinus
ponderosa stands, and on raw shale slopes.

Poa sandbergii

The associations where Poa sandbergii is a dominant (at least in some stands) are the
Sarcobatus vermiculatus-Agropyron dasystachyum, Artemisia tridentata-Agropyron
spicatum, Agropyron spicatum-Bouteloua gracilis, and Artemisia tridentata-Agropyron
dasystachyum associations. It is never more than a subordinate grass in the Artemisia
tridentata-Bouteloua gracilis disclimax, and it occurs only rarely in other associations.

Smith (1969) determined that Poa was important in all of his vegetation groups, but it
was apparently most important on sites dominated by Artemisia and rhizomatous species
of Agropyron. Mackie (1970) also found Poa to be highly associated with rhizomatous
species of Agropyron and Sarcobatus. Others (Coupland 1950, Wright and Wright 1948)
reported that Poa was a minor constituent of associations dominated by Stipa comata and
Bouteloua gracilis and occurred only rarely in Agropyron sp/'catum-dominated associa-
tions. It is difficult to conclude with which major grass species Poa is most strongly asso-
ciated, although there are indications that rhizomatous species of Agropyron are very
important associates. Grazing apparently influences the importance of Poa in a plant
community (Daubenmire and Colwell 1942, Daubenmire 1970). Data from southeastern
Washington show a reduction in coverage resulting from heavy cattle grazing and an
increase as a result of heavy sheep grazing (in areas where Bromus tectorum is important).
Some variations in coverage of Poa in the triangle may be due to grazing patterns rather
than site differences; general observations indicate this species is most abundant on clay
or clay loam soils.

Agropyron dasystachyum

On the basis of canopy coverage, this species is the second most important mid-grass
(behind Agropyron spicatum) in the triangle. It possesses a wide ecologic amplitude,
resulting in a wider range of importance in triangle habitat types than any other plant. The
only associations where it was not found were the juniperus horizontalis-Carex parryana
and Poa pratensis-Artemisia ludoviciana associations, although coverage was low in the
Artemisia cana habitat type.

Compared to its very similar relative, Agropyron smithii, Agropyron dasystachyum
seems to be more adapted to upland sites with fine-textured (silty or clayey) and often
saline-alkaline soils; Agropyron smithii is most common in moist, low-lying areas such as
swales, footslopes, and floodplains (Holscher 1945). Both species often occur together in
about equal quantities and frequently Agropyron smithii, instead of Agropyron dasys-
tachyum, is found on upland clay sites in Artemisia tridentata/ Bouteloua gracilis cover
types. Coupland (1961) states that A. dasystachyum tends to be more abundant on fine-

37

textured soils than A. smithii and that A. smithii is more abundant on disturbed soils and
sites where Bouteloua gracilis is a dominant. These observations agree with general
observations in the triangle. A. dasystachyum constitutes about 80 per cent of the rhi-
zomatous Agropyron on fine-textured lacustrine soils of Canadian mixed prairie
(Coupland 1961).

Per cent frequency data from Smith (1969) show that A. smithii was more abundant in
more vegetation groups than A. dasystachyum and that the relationship with fine and
coarse-textured soils was not the same as those discussed above. His lack of distinction
between heavily and lightly grazed sites, and the fact that he was working in a large area
east and north of the triangle in addition to the triangle, possibly caused him to report
results different from those observed by this researcher.

Artemisia frigida

Artemisia frigida is very abundant in the triangle, although some of this abundance
results directly from man's activities. Two sites where it is a dominant taxon were plowed
and seeded to Agropyron desertorum. It is also one of the dominant taxa in the unplowed
(but grazed) areas of the Agropyron spicatum/ Agropyron smithii habitat type. While the
coverage of A. frigida seems to be negatively correlated with the coverage of bare ground,
it would not be a valid conclusion that bare ground prevents its growth. Other factors
responsible for the absence of plant and litter cover probably are also responsible for the
absence of Artemisia. Sites where Artemisia is least abundant usually have poorly devel-
oped soils with greater than 20 per cent coverage of bare ground, and occur in the Pinus
ponderosa/ Artemisia tridentata, Rosa arkansana/Thermopsis rhombifolia, Juniperus
horizontalis/Carex parryana, Artemisia tridentata/Koeleria cristata, Atriplex dioica/
Gutierrezia sarothrae, and Artemisia tridentata/ Agropyron dasystachyum habitat types.
The factors (not all found in each site) responsible for the high coverage of bare ground on
these sites, and possibly the low canopy coverage of A. frigida, are presence of raw, par-
tially weathered shale with poor water-holding capacity near the surface; silty, calcareous,
unstable soil; extremely dense impermeable clay "soil," and self-mulching clay soils
which destroy the roots of many plants.

Weaver (1919, 1920) states that A. frigida has a deep, extensive root system. A. frigida is
better adapted to sites with an abundance of Agropyron spicatum than to those with
mostly Bouteloua gracilis, either because of inherent differences in site potential or be-
cause of grazing pressure differences. Wright and Wright (1948) found that A. frigida was
important in three vegetation types where Agropyron spicatum was at least a major grass,
if not a dominant; in three vegetation types where Bouteloua gracilis was a major grass (in
two of these, /Agropyron spicatum was a dominant), and in two types where Koeleria was a
dominant. Quinnild and Cosby (1958) noted that /Artemisia was the most common forbon
their relict mesas, and Coupland (1961) stated that it occurred more frequently on
medium-textured than fine-textured soils, and was the major forb in all mixed prairie
communities.

Evidence suggests that Artemisia increases in abundance due to various grazing prac-
tices. Lewis et al. (1956) reported that the species increased with grazing in western South
Dakota; Ellison (1960) concurred, basing his conclusions on studies of the area around
Mandan, North Dakota. Others agreeing that Artemisia increases with grazing were
Beetle 1950, Sarvis 1920, Johnson 1956, and Lodge 1954. Measurements of dry matter pro-
duction of A. frigida in the Artemisia tridentata-Agropyron spicatum association of the
triangle (unpublished data), both inside an exclosure (standing for three years up to the
time of clipping) and outside (subjected to heavy spring and early summer grazing),
strongly indicate a direct relationship between grazing intensity and productivity of A.
frigida. Because of this, the abundance of Artemisia in the triangle is probably higher now
than it was before livestock were introduced into the area.

Vicia americana

Little mention of this species exists in the literature of the region. Mackie (1970) lists
Vicia as being important only in his Artemisia tridentata-Agropyron smithii association.
Data of Smith (1969) indicate it as being most abundant in his Artemisia-Agropyron and
Artemisia- Koeleria-Bouteloua groups.

38

Although Vicia is widespread in the triangle, it rarely occurs on habitat types in early
stages of primary succession. These include the Atriplex dioica/Gutierrezia sarothrae,
Artemisia tridentata/Koeleria cristata, Rosa arkansana/Thermopsis rhombifolia, and
juniperus horizontalis/Carex parryana habitat types. It also does not occur on sites where
the vegetation canopy coverage is extremely high, as in the Poa pratensis/ Artemisia ludo-
viciana habitat type. Its greatest occurrence is in the Agropyron spicatum-Agropyron
smithii and Artemisia tridentata-Agropyron dasystachyum associations. Because bare
ground coverage is low in the former and high in the latter, it cannot be concluded that
low abundance of Vicia is directly related to bare ground coverage, although many sites
where the species is absent have low plant coverage.

Taraxacum officinale

This invader (Davis 1952), important as wildlife food, has become established to a
small extent in the triangle as it has over most of the country. This taxon was present in few
sample plots and no definite statement can be made as to frequency and abundance by
habitat types. Sample plots with the greatest coverage of Taraxacum were in the Agro-
pyron spicatum/ Agropyron smithii habitat type. Taraxacum is usually observed in moist
swales and footslopes of the gravel-capped benches and moist disturbed areas, such as
roadside ditches, where the soil is not saline-alkaline.

Tragopogon dubius

The distribution of Tragopogon in the triangle was very similar to that of Taraxacum. It
occurred mostly in moist disturbed areas such as roadside ditches. It was never abundant
enough to be considered a dominant.

Selaginella densa

Although this short, non-flowering species (related to the ferns) apparently is not
important as food for animals, it is a good indicator of habitat types and possibly of range
condition. It may also be important in helping prevent soil erosion when other cover is
removed.

Van Dyne and Vogel (1967) found that Selaginella was most abundant in places where
Bouteloua and Stipa comata were dominant. It was also associated with the Stipa comata-
Agropyron smithii, Agropyron smithii-Muhlenbergia cuspidata, and Agropyron spicatum
types. They determined that Selaginella coverage was least on relatively deep soils and
greatest on soils of medium texture. Grazing was shown by that study to decrease cover-
age of the species. Smoliak (1965) found that compared to control areas, coverage in
southeastern Alberta was higher on areas subjected to rotation grazing and less on con-
tinuously grazed areas.

Coupland (1950) states that Selaginella is least abundant on clay soils and most abun-
dant on soils of medium texture. He concurred with Van Dyne and Vogel that heavy
livestock use decreased coverage of Selaginella, probably as a result of trampling effects.

In the triangle, Selaginella is most abundant in the Artemisia tridentata-Agropyron
spicatum and Agropyron spicatum-Agropyron smithii associations. When considering
only canopy coverage, it appeared to be a dominant in these associations, but due to its
very low stature and moisture requirements, this probably was not the case (Clark et al.
1943). Selaginella is a minor associate of the Artemisia tridentata/Bouteloua gracilis cover
type and is absent in habitat types with clay soils, silty soils, and raw shale substrates. The
presence or absence of this species on untilled sites is a very strong indicator of whether a
site supports the Artemisia tridentata-Agropyron spicatum association or the Artemisia
tridentata-Agropyron dasystachyum association. Comparisons of abandoned plowed
sites and unplowed sites within the Artemisia tridentata/Agropyron spicatum and Agro-
pyron spicatum/ Agropyron smithii habitat types show that treatments of this sort virtually
eliminate Selaginella from the plant community for many years. Thus, within these habitat
types, the degree of Selaginella coverage is a good indicator of whether or not a site has
been plowed and abandoned, even if most other indicator species have disappeared.

The effects of grazing on coverage of Selaginella in the triangle are unclear, and more
intensive studies would be needed to determine this.

39

Habitat Types and Management

Effects of Grazing on the Artemisia tridentata/ Agropyron
spicatum Habitat Type, Bouteloua gracilis Phase, and the
Artemisia tridentata/ Bouteloua gracilis Cover Type

The heavily grazed, gravel-capped terraces throughout the triangle support stands of
Artemisia and shortgrasses such as Bouteloua, Stipa comata, Poa sandbergii, and Koeleria.
Scattered patches of Agropyron spicatum exist throughout these areas, increasing toward
the edges of the terraces. Since heavy grazing has been the rule on these terraces, cer-
tainly much heavier than the pressure exerted by wild ungulates, certain components of
the original vegetation community probably have decreased and others have increased.

On the basis of known effects of heavy grazing on various species of plants, it can be
assumed that what once may have been an Artemisia tridentata-Agropyron spicatum
association is now an Artemisia tridentata-Bouteloua gracilis disclimax. Evidence is abun-
dant that Bouteloua increases in abundance with heavy grazing and that Agropyron
spicatum is strongly decreased or even eliminated (Coupland 1961, Daubenmire 1970,
Tisdale 1947, Stoddart 1946, Mcllvanie 1942, Heady 1950, Blaisdell and Pechanec 1949, and
Cooper 1953). Good stands of Agropyron spicatum occur on what appear to be moder-
ately grazed areas of the triangle. While evidence is strong that overgrazing may have
virtually eliminated Agropyron spicatum from the gravel terraces,it possibly may not have
existed there in much greater quantities before livestock grazing than it does now. These
areas, at best, seem to be only slightly better than marginal habitat for the species. How-
ever, Agropyron spicatum bunches persisting only beneath Artemisia tridentata bushes,
where they are inaccessible to cattle, seem to indicate otherwise. One site in the extreme
southeastern part of the triangle, subjected to very light grazing at most, supports a
vigorous stand of Agropyron spicatum and Artemisia; outside the fence, where grazing is
heavy, the only Agropyron spicatum plants to be found are under the protection of sage-
brush bushes.

Grazing causes changes in vegetation because of its direct, often detrimental, effects
on plants and its effects on soil and microclimate. Selectivity by livestock for certain types
of plants causes some species to be grazed more heavily than others. A general presump-
tion is that shortgrasses are harder for cattle to eat and therefore would tend to increase at
the expense of more exposed taller grasses. However, other complicating factors such as
differences in palatability, elevation of growing point above the ground, and ratio of
fertile to vegetative stems influence the susceptibility of a grass to grazing damage
(Branson 1953). Elevated growing points, high ratios of fertile to vegetative stems, and high
palatability are characteristics contributing to detrimental effects if a grass is grazed
heavily.

In this habitat type, Ellison (1960) reported that under moderate continuous grazing,
Agropyron smithii, Stipa comata, Koeleria cristata, and Psoralea argophylla are con-
sidered as decreasers, whereas Bouteloua and Artemisia frigida are increasers. Branson
(1953) also reports that Agropyron smithii and Koeleria cristata are decreasers. Other
reports on Koeleria cristata are somewhat conflicting. Beetle (1950) and Clark (1930)
report it as a decreaser; Vogel and Van Dyne (1966) report it as an increaser. Tueller and
Blackburn (1974), Vogel and Van Dyne (1966), Smoliak (1974), Clark (1930), Craddock and
Forsling (1938), Larson and Whitman (1942), Smoliak (1965), and Lodge (1954), state that
Stipa comata is a decreaser and Smoliak (1974) states that heavy sheep grazing increases
basal area of 8oute/oua and decreases basal area of Stipa comata and Agropyron smithii.
Data from sample plots, comparing spring-summer grazed stands in this habitat type with
light to moderately grazed stands (Table 2), definitely show a large increase in Bouteloua
canopy coverage with increased grazing pressure. Changes in dominance of other species
are less definite, although Stipa comata appears to be slightly more abundant on heavily
grazed sites than on lightly grazed ones; but, as noted above, results of others are dif-
ferent (Ellison 1960, Smoliak 1965, and Sarvis 1941). The differences, however, may result
from the fact that their work was done in areas more favorable climatically and edaphically
for Stipa comata and involving different ecotypes of the species. Cooper (1953) reported
that Agropyron smithii and /Agropyron spicatum decreased with heavy grazing on certain
Artemisia ranges near Tensleep, Wyoming, whereas Artemisia tridentata was an increaser.

40

TABLE 2.-

-Percent Canopy Coverage Comparisons

Between

Adjacent Grazed and Ungrazed Stands

Habitat Type

Sarcobatus-

Artemisia-

Agropyron

Agropyron

Stand No.

Stand No.

14 15

57 56 73

74

+*

- + —

+

Bare ground

14 25

2 11 8

13

Grass

44 23

52 46 55

43

Forbs

12 10

9 6 16

9

Selagmella densa

1

Lichens

8 3

1 2

6

Flat litter (mulch)

57 35

75 57 69

46

Standing litter

18 5

30 10 34

6

Artemisia tridentata

7 3

2 19

24

Sarcobatus vermiculatus

5 <1

Agropyron spicatum

25 1 46

19

A. dasystachyum

11 10

5

A. smithii

2

<1 < 1

< 1

Bouteloua gracilis

< 1 7

2 4

14

Koeleria cnstata

8 < 1

3 2 2

2

Poa sandbergii

11 2

14 5 1

1

Stipa comata

4

5

Distichlis slricta

< 1 <1

Carex eleocharis

3 <1

5 < 1

< 1

Bromus /apomcus

3

4 9

Gutierrezia sarothrae

< 1 <1

<1 3

Opunlia polyacantha

4 6

< 1

< 1

Artemisia trigida

4 3

< 1 < 1 < 1

< 1

Taraxacum officinale

1

< 1

Tragopogon dubius

<1 <1

Achillea millefolium

2

< 1

< 1

' — = no grazing

4- = grazing

Of the grazed stands, 15 and 56

were spring, summer pastures; 74 was a spring through fall pasture.

41

Data of Ross et al. (1973), from stands in an Artemisia tridentata/Agropyron spicatum
habitat type, generally show decreases in per cent composition by weight of Agropyron
spicatum and Stipa comata, little change in Agropyron smithii and Koeleria cristata, and
increases in Artemisia tridentata with grazing, although results are somewhat conflicting
due to insufficient data.

As noted above, microclimatic changes resulting from grazing may shift vegetation
composition on a site. Removal of leaves by livestock prevents the formation of litter
(mulch); Reed and Peterson (1961) determined that heavy grazing on the Ft. Keough
Experimental Range near Miles City reduced litter cover by 50 per cent. Presence of litter
helps prevent the sun from baking the soil surface, provides a source of organic material
for incorporation into the soil surface (Hopkins 1954), and reduces the force of raindrops
striking the ground. The force of livestock hooves on the ground compacts the surface
and destroys the surface structure, resulting in a greater bulk density and lower per-
meability and water-holding capacity (Rauzi and Hanson 1966). Removal of plant material
decreases shading of the soil surface with subsequent higher surface temperatures
(Daubenmire and Colwell 1942) and evaporation of soil moisture. All of these factors
result in a more xeric site with more xerophytic vegetation composition than existed
previously. One of the best examples of this is the increase of Bouteloua gracilis in areas
which have become more xeric (Coupland et al. 1960, Ellison 1960).

From the evidence discussed above, and the data in Table 2, a relatively undisturbed
Artemisia tridentata-Agropyron spicatum association, containing moderate amounts of
Bouteloua gracilis, Stipa comata, Agropyron smithii, Artemisia frigida, Koeleria cristata,
Poa sandbergii, and Agropyron dasystachyum, upon the advent of heavy grazing, would
tend to become an Artemisia tridentata-Bouteloua gracilis disclimax with slightly de-
creased amounts of Stipa comata, strongly decreased amounts of Agropyron spicatum,
and only slightly different amounts of Agropyron smithii, Agropyron dasystachyum,
Koeleria cristata, and Poa sandbergii. Artemisia tridentata would increase moderately.

Because other authors (Coupland 1961, Wright and Wright 1948, Hanson and
Whitman 1938, Dix 1958, and Quinnild and Cosby 1958), working in regions surrounding
central Montana, recognized climax vegetation associations dominated by Bouteloua
gracilis and Stipa comata, it is possible a climax habitat type dominated by these two
species may occur within the triangle. However, soils in the triangle are generally fine-
textured, limiting abundance and vigor of Stipa comata (Coupland 1961). Stipa comata
does not appear to be a dominant in any Artemisia stand within the triangle, regardless of
the grazing treatment. Although Bouteloua is a dominant grass in many overgrazed situ-
ations, it does not seem to be a dominant in any lightly or moderately grazed area.

Effects of Cultivation on the Artemisia tridentata/Agropyron
spicatum Habitat Type, Bouteloua gracilis Phase, and the
Artemisia tridentata/ Bouteloua gracilis Cover Type

Many gravel-capped terraces in the triangle were plowed and seeded to wheat and
other grains during the homestead era, followed by abandonment during the Depres-
sion. Some fields were later plowed and seeded to crested wheatgrass (Agropyron
desertorum). Following the abandonment of these fields, the vegetation continues to
undergo secondary succession. A long-lasting effect of plowing these soils is to bring the
clay "B" horizon to the surface and mix it with the coarser-textured and more friable
topsoil, in effect changing the soil to one that is denser and less permeable at thesurface.
Hundreds, and perhaps thousands, of years will be necessary for the soil to regain the
same profile as in adjacent, undisturbed areas. At least some vegetation differences may
persist for as long as the soil differences exist. In actuality, the seeding of crested wheat-
grass has created a new habitat type, but one on which the climax vegetation association
for the new site has not yet developed.

Presently, the vegetation composition on previously plowed sites resembles the
composition on "immature" (and usually fine-textured) soils in the triangle derived from
shale. Because of the higher clay content, Bouteloua gracilis and Selaginella densa are
almost absent, whereas Stipa viridula, Agropyron smithii, and Agropyron dasystachyum
are more abundant than on nearby similar, but untilled, sites. If Agropyron desertorum
was seeded, it persists in varying amounts. The effect seems to be to partially convert an

42

Artemisia tridentata-Bouteloua gracilis disclimax (or Artemisia tridentata-Agropyron
spicatum association) to an Artemisia tridentata-Agropyron dasystachyum disclimax. The
effects of plowing on Agropyron spicatum in this habitat type are unclear.

Effects of Grazing on the Artemisia tridentata/ Agropyron
dasystachyum Habitat Type, Agropyron smithii Phase

Little can be said concerning livestock grazing effects in this habitat type due to a lack
of information. Soils are unstable and normally undergo substantial geological erosion.
Placing livestock on such sites would increase erosion rates, with subsequent detrimental
effects on vegetation.

As previously noted, Agropyron spicatum and Agropyron smithii are usually de-
creases, so presumably they would decrease in this habitat type. Another important
constituent of this type, Stipa viridula, may also be a decreaser (Ross et al. 1973), although
data to support this are thin. Effects of grazing on Agropyron dasystachyum, the major
dominant grass of the type, are unknown. Artemisia tridentata apparently increases.
Bouteloua, Stipa comata, Artemisia frigida, and Selaginella densa do not exist in this habi-
tat type, and apparently do not invade as grazing pressure is applied. Two important forbs
of this habitat type, Vicia americana and Bahia oppositifolia, were found to have been
decreased three to five times by heavy grazing on the Ft. Keough Experimental Range
(Reed and Peterson 1961).

Effects of Grazing and Cultivation on the

Sarcobatus vermiculatus/ Agropyron dasystachyum Habitat Type

On some areas of this habitat type, where a topsoil developed and was able to re-
main, Bouteloua is the dominant grass species, possibly because of grazing effects. It is
difficult to imagine what grass(es) may have decreased at the expense of the Boute/oua on
these sites, but a rhizomatous species of Agropyron was probably one of them. Judging
from evidence of severe soil erosion, the areas with a topsoil, and dominated by Sarco-
batus, were probably more extensive in the past than they are now. Where severe erosion
has occurred, very little except bare ground can be found between Sarcobatus bushes.
These bushes, in some very heavily grazed areas (during the summer), are severely
hedged and probably less abundant than they would be without grazing. A common
observation in the triangle (apparently different from some other areas, Daubenmire
1970) is the heavy use of Sarcobatus by cattle to the extent that it has been almost elimi-
nated from sites where apparently it should be a dominant plant. This was deduced from
observations comparing adjacent heavily grazed and lightly grazed Sarcobatus stands
separated by fences. The original coverage of Sarcobatus in the triangle is almost as diffi-
cult to assess as that for Artemisia.

Sarcobatus bottomlands are often converted to alfalfa (Medicago sativa) or to hay-
fields planted with tame grasses. While alfalfa and hayfields have also been established in
other habitat types, such as those dominated by Artemisia tridentata and Artemisia cana,
they are almost always found on bottomlands.

Effects of Grazing and Cultivation on the
Agropyron spicatum/ Agropyron smithii Habitat Type

Little is known of the effects of grazing on vegetation of this habitat type. Consid-
ering known reactions of individual species to grazing in other areas as discussed
previously, grazing presumably would decrease Agropyron spicatum, Agropyron smithii,
Koeleria cristata, and Stipa comata, and increase Bouteloua gracilis and Artemisia frigida.
Moderate grazing of this habitat type has not resulted in the establishment of Artemisia
tridentata. When soil of this habitat type is planted with Agropyron desertorum, few
native grasses remain except Koeleria cristata and Poa sandbergii. Canopy coverage of
forbs is reduced by more than half, and the number of species is sharply reduced. Arte-
misia frigida remains as the most common forb.

43

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47

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48

APPENDIX A, TABLE 1.- Percent Constancy and Percent Canopy

Habitat
Type

ARTR/

AGS!'

1 2
c cc

SAVE/
POSA

ARTR/
AC DA

ARTR/
AC DA

ARTR/
KOCR

ROAR/
THRH

P ha s e

No. Stands Sampled

LI. 6

1.7

Con i f e r Tree s

Pinus ponder osa

Shrubs

Artemisia tr identata 90
Opuntia pol gacantha 80
Sarcoba tus

vermicu la tus
Yucca glauca 5 P

Rosa arkansana
Artemisia long i fol ia
Chrysothamnus

nauseosus
Jun i per us

hor i zon til i s
Chrysothamnus

v i scidiflorus
Artemisia cana

Perennial Graminoids

Agropyron spicatum 65 10.5

A. dasystachyum 55

Bou teloua gracilis 90

Stipa comata 100

Koeleria cr i stata 90

Agropyron smit hi i 90

Poa sandbergi i 95

Carex stenophylla 85
Ca lamovi 1 fa

1 ong i fol i a

Calamogrostis 25

mon tanens i s

3.3

7.5
4.2
4. 4
1.4
1.4
1. 3

Ca rex

Oryzo
Carex
Muhle
c
Andro
Arist
Festu
Stipa
Poa p
Phleu
Agrop
Juncu
Luzul
Typha
Disti
Carex
C . fo
Si tan

parryana
ps is hymenoides

fili fol ia
nbergia
uspi da ta
pogon scoparius
i da long i se ta
ca idahoens i s

vi ridula
ratens is
m pratense
yron repens
balticus
mul ti flora

la t i fol ia
chl is s t r icta

rostra ta
enea

on hy s tr i x

Annual Graminoids
Schedonnardus

panicula tus
Vul pi a octof lor a
Bromus ja ponicus
B. tectorum

Sub Shrubs

Er iogonum

pa uc i f lor urn
E. flavum
Guti errezia

sarothrae
Atriplex dioica
Artemi s ia

frigida

Forbs

Astragal us

bi sulcatus
V ic ia amer icana
Alyssum alyssoides
Penstemon nitidus
Oxytropis sericea

10 P

15 P

37

.3

40 P

25

.4

20 .3

90 5.9

70 1.6
10 2.6

3.5
2.2

12

100

75

100
37

100
87

75 1.4

37 .2

92 14.0
42 .5

83

75
33
))
83
67
100
42

9.6
5.2

.2
5.0
3.2
4. 1

.6

8 P

67 1.0

67 1.4

92 .6

50 6.6
50 1.0

50 .4

86 9.8
57 .4

57
100
71
86
86
71
71
57

6.2
7.7
2.6
3.0
4.7
.6
1.5

28 .1
86 4.3

50 1.9

28 .9

100 2.4

71 .9

71 .9
14 P

50 5.5
25 .5

100
75

50
50
25
25
25
75
50
75
50

25

1.0
3.8

25 .9
50 .3

25 P

Coverage of all Sampled Species by Habitat Types and Phases

JUHO/ PIPO/
CAHA ARTR

.3

c cc

65 5.2
15 .3

35 6.6
90 12.7

30 1.4
25 .4

5 P

ATDI7
ARTR

c cc

100 25*

100 4.8
50 .3

50 19.2

100 2.9

100
50

.5
1.0

2 P

2 P

12 .1

7 P

52 6.8
40 6.1

POPR/ ARCA/

ARLU AGSM

3

C CC c cc

AGSP/
AfiSM

ARTR/
FEID

67 19.6

50
50

50

50

7

2.2

100 5.9

92

68.1

50 13.1

12

1.6

17

6.7

7

4.6

10

.9

5

2. 2

5

4.0

22

5.0

50 . 1

50 .1
50 3.9

30 .9

86 8. 2
57 1.2
71 1.3
100 9.5
86 4.3
86 6.1
86 3.0
57 .2
14 3. 5
29 P
14 1.9

71 .4
14 1.7

14 .1
43 .4

100 9.0

71 1.3
14 P

67
100

3.5
.6

33 .1

100
33

67
100
100
100
67
67

7.7
1.7

. 1
3.6
3.0
1.1
P

.2

1.9

P

100 5.4
33 .7

I ) 1.9
33 P
67 .7

100 5.4
33 .7

67 .9

MUCU/
ANSC

3
c cc

7 1.1

40
35

7
12
60

7

7.3
2.7
.5
2.2
2.4
1.4

42 1.6

10 .3

87 13.7

65 9.6

35 5.0

15 2.5

42 1.6

10 . 3

87 13.7
65 9.6
35 5.0

15 2.5

5 P
77 9.9

APPENDIX A, TABLE 1 (continued)

Habitat
Type

RTR

/

SAVE/

ARTR/

ARTR/

ARTR/

ROAR/

GSP

POSA

AG DA

AGDA

KOCR

THRH

1

2

Phase

No. Stands Sampled

20

12

Erysimum asperum
Aster canescens
Iva axillaris
Draba brachycarpa
Lepidium dens i florum
Alii urn texti le
Plantago spinulosa
Bahia opposi ti folia
Sphaeralcea cooccinea
Thlaspi arvense
Phacelia linear i s
Rorippa i s landica
Col lomia 1 inearis
Gaura coccinea
Lomatium or ientale
Plantago patagonica 45

Arenar ia bookeri 30

Macbaer anther a

gr indelo ides
Aster falcatus
Lesquerella alpina 5

Astragalus gi lvi florus 15
Townsend ia hooker i
Phlox hoodii
Astragalus spa tula tus
Senecio canus
Psoralea tenui flora
Thermops i s rhomb i folia
Potenti 1 la

pennsyl vanica
Melilotus officinale
Artemis ia ludoviciana
Aster chi lens is
Pol ygonum douglas i i
Madia glomerata

Ci rsium undula turn
Ra tibida column! fera
Ambros ia artemi si fol ia
Achillea millefolium
Epilobium paniculatum
Grind el ia squarrosa
Sonchus arvensis
Comandra umbellata
Er igeron pumilis
Psoralea argophyl la
Heuchera parvi flora
Tragopogon dubius
Astragalus miser
Orobanche fasciculata
Taraxacum officinale
Er igeron caes pi tosus
Hel ianthus petiolaris
Zygadenus paniculatus
Artemisia biennis
Androsace

septentrionalis
Aster pansus
Ci rsium flodmani
Sisymbrium altissimum
Liatris punctata
Balsamorrhi za sagittata
Thelasperma subnudum
Antennar ia rosea
Petalostemon purpureum
Linum perenne
Cerastium berr ing ianum
Paronychia sessili flora
Petalostemon candidum
Sol i dago missouriensis
Mymenoxys acaulis
Hymenopappus filifolius
Orobanche 1 udoviciana
Collomia tinctoria 10

Musineon divaricatum 10

10

P

40

P

40

P

35

55

5

P

25

.'0

50

Nos toe

Selaginella densa

Moss

Lichens

Bare Ground

Mulch

15

89

5 P

5.6

9.5

48.6

12

P

12

25

P

87

P

25

P

75

25 P

12 P

12

50 P

25
62

5.2

100 5.4
16.4
41.1

25

P

33

P

8

P

67

.2

8

P

8

P

17

P

8

P

8

P

33

.7

33 .4

17 .3

25 .2

8 P
8 P

17 P

8 P

8 .1

17 .4
8 P

92 3.2
27.8
60.9

50
100

50
50

2.2
4.2

2.1

50 1.3

50 .4

23.9
40.4

14

P

14

P

28

P

14

P

71

P

14

P

28

P

00

1.9

50

1.1

43

1.3

14

1.3

14

P

28

1. 3

14

P

57

3.3

14

P

14

P

14

P

100

2.7

28 .6
71 .2
14 P

14 .1

28 .3
14 P

14 P
28 P

14 P

43 .3

28 P

86 1.6
30.6
25.6

25 P
25 P

25 .2
25 P
50 .2

25 P

75 1.3
23.2
26.9

'Constancy percent
'Canopy coverage percent

frequency percent

P-present, but less than .1% canopy coverage

JUHO/

PIPO/

ATDI/

POPR/

ARCA/

AGSP/

ARTR/

MUCU7

CAHA

ARTR

ARTR

ARLU

AGSM

AGSM

FEID

ANSC

c cc

c cc

3

c cc

3
c cc

c cc

c cc

c cc

3
c cc

L

2

1

1

2

7

3

1

15 .1

40 1.4

100 P

2 P
2 P

14 P
14 P

33 P

67 P

7 P

50 P

43 .2

33 P

5 .7

50 P

14 P

67 1.2
33 .3

33 .1

20 .3

17 3.2

20 .5

10 1.5

29 P
57 .3
43 .2

67 P

5 P

15 .3

12 6.3

52 18.0

7 1.2

5 1.6

5 P

20 '..9
5 !■
5 .1

50 P

14 .3

100 .6

67 16.9
5 .9
2 P

50 P
50 .4

57 1.8

67 .2

20 .2

50 .3

29 1.4
43 .8
29 1.1
14 .3

33 P
67 .6
33 .3

5 . 15

86 .7
29 .4

67 P
33 P

2 P

20 .2

29 P
43 .6
14 T
14 P
14 P
14 .7

33 .1

2 P

7 P

42 .9

50 P

57 .4

25 1.6
29 .1
14 P
43 .3

14 P
43 .1
14 P
14 .2
71 3.8

14 P

33 P

33 .7

33 P
33 P

20 .4

7 .2

40 .6

5 .4

2 .4

20 5.8

65 4.5

15 .1

2 .7

10 .5

62 1.7

5 P

2 P

50 .9

71 26.7

100 9.0

2 P

50 P

100 4.4

100 1.4

87 4.9

50 P

71 .6

100 5.9

90 7.6

24.9

25.0

62.6

.2

5.4

2.1

2.9

15.0

29.8

3.7

96.0

96.0

76.3

74.2

55.3

50.0

APPENDIX A TABLE 2 —

ACMI

ACNE

AG DA

AGDE

AGRE

AGSM

AGSP

ALAL

ALTE

AMAR

ANRO

ANSC

ANSE

ARBI

ARCA

ARFR

ARLA

ARLO

ARL02

ARHO

ARLU

ARTR

ASBI

ASCH

ASFA

ASGI

ASMI

ASPA

ASSP

ATDI

BAOP

BASA

BESY

BIVU

BOGR

BRJA

BRTE

Achillea millefolium

Acer negundo

Agropyron dasystachyum

A. desertorum

A. repens

A. smithii

A. spicatum

Alyssum alyssoides

Allium textile

Ambrosia artemisifolla

Antennaria rosea

Andropogon scoparlus

Androsace septentrionalis

Artemisia biennis

A. cana

A. frigida

Arctium lappa

Aristida longiseta

Artemisia longilolia

Arenaria hookeri

Artemisia ludoviciana

A. tridentata ssp. wyomingensis

Astragalus bisulcatus

Aster chilensis

A. talcatus

Astragalus gilviflorus

A. miser
Aster pansus
Astragalus spatulatus
A triplex dioica

Bahia oppositifolia
Balsamorrhiza sagittata
Beckmannia syzigachne
Bidens vulgata
Bouteloua gracilis
Bromus lapomcus

B. tectorum

Western yarrow

Box-elder

Thickspike wheatgrass

Crested wheatgrass

Ouackgrass

Western wheatgrass

Bluebunch wheatgrass

Pale alyssum

Textile onion

Annual ragweed

Rose pussytoes

Little bluestem

Northern rockjasmine

Biennial wormwood

Silver sagebrush

Fringed sagewort

Great burdock

Red threeawn

Longleat sage

Hooker's sandwort

Cudweed sagewort

Wyoming big sagebrush

Two-grooved milkvetch

Creeping aster

Creeping white prairie aster

Three-leaved milkvetch

Weedy milkvetch

Tufted white prairie aster

Draba milkvetch

Rillscale saltbush

Opposite leaf bahia

Arrow-leaved balsamroot

Sloughgrass

Beggarticks

Blue grama

Japanese brome

Cheatgrass, downy brome

CAEL

CAFI

CAFO

CAHA

CALO

CAMO

CANE

CAREX

CARO

CEBE

CHNA

CHVI

CIDO

CIFL

CIUN

COLI

COTI

COUM

CRDO

Carex stenophylla (eleocharis)

C. tilifolia

C. toenea

C parryana (hallii)

Calamovilla longilolia

Calamogrostis montanensis

Carex nebrascensis

C. ssp.

C. rostrata

Cerastium bemngianum

Chrysothamnus nauseosus

C viscidiflorus

Cicuta douglasii

Cirsium llodmani

C. undulatum

Collomia linearis

C tmctoria

Comandra umbellata

Crataegus douglasii

Narrow-leaved sedge
Thread-leaved sedge
Dryland sedge
Parry sedge
Prairie sandreed
Plains reedgrass
Nebraska sedge
Sedge

Beaked sedge
Alpine chickweed
Rubber rabbitbrush
Green rabbitbrush
Western water-hemloek
Flodman's thistle
Wavy-leaved thistle
Narrow-leaved collomia
Yellow-staining collomia
Bastard toadflax
Black hawthorn

DIST
DRBR

EPPA
ERAS
ERCA
ERFL
ERMU
ERPU

FEID

GACO
GLLE
GRSQ
GUSA

Distichlis stricta
Draba brachycarpa

Epilobium paniculatum
Erysimum asperum
Engeron caespitosus
Eriogonum flavum
E paucillorum (multiceps)
Erigeron pumilis

Festuca idahoensis

Gaura coccinea
Glycyrrhiza lepidota
Grindelia squarrosa
Gutierrezia sarothrae

Alkali saltgrass
Shortpod draba

Tall annual willow-herb
Rough wallflower
Tufted fleabane
Yellow buckwheat
Few-flowered buckwheat
Shaggy fleabane

Idaho fescue

Butterfly weed
Wild licorice
Curlcup gumweed
Broom snakeweed

HEUN
HEPA
HEPE
HYAC
HYFI

Helianthella umllora
Heuchera parviflora
Helianthus petiolaris
Hymenoxys acaulis
Hymenopappus filifolius

Little sunflower
Small-leaved allumroot
Prairie sunflower
Stemless hymenoxys
Hymenopappus

IVAX

Iva axillaris

Povertyweed

JUBA
JUHO

Juncus balticus
Jumperus horizontalis

Baltic rush

Creeping juniper, horizontal lumper

KOCR

Koeleria cristata

Prairie junegrass

53

LEAL
LEDE

Lesquerella alpina
Lepidium densiflorum

Alpine bladderpod
Prairie pepperweed

Species Symbols and Common Names

LIPE

LIPU

LIRI

LOOR

LUMU

MACA
MAGL
MAGR
MEOF
MUCU
MUDI

OPPO
ORFA
ORHY
ORLU
OXSE

PASE

PECA

PENI

PEPU

PHHO

PHKE

PHLI

PHPR

PIPO

PLPU

PLSP

PODE

PODO

POPE

POPR

POSA

PRVI

PSAR

PSME

PSTE

PUAI

RACO

RHTR

RIBES

ROAR

ROIS

ROSA

ROWO

RUMEX

SAAM

SAIN

SARI

SARU

SAVE

SCAM

SCIRP

SCPA

SCVA

SECA

SEDE

SHAR

SIAL

SIHY

SOAR

SOGI

SOMI

SPCO

SPGR

STCO

ST VI

SUFR

SUOL

SYOC

TAOF

THAR
THMA
THRH
TOHO
TRDU
TYLA

URDI

VIAM
VUOC

YUGL

ZYPA

Linum perenne
Liatris punctata
Linum rigidum
Lomatium orientate
Luzula multitlora

Machaeranthera canescens (Aster canescens)

Madia glomerata

Machaeranthera grindeloides (Haplopappus nuttallii)

Melilotus officinale

Muhlenbergia cuspidata

Musineon divaricatum

Opuntia polyacantha
Orobanche fasciculata
Oryzopsis hymenoides
Orobanche ludoviciana
Oxytropis sericea

Paronychia sessitiflora

Petalostemon candidum

Penstemon nitidus

Petalostemon purpureum

Phlox hoodii

P. kelseyi

Phacelia linearis

Phleum pratense

Pinus ponderosa

Plantago patagonica (purshii)

P. spinulosa

Populus deltoides

Polygonum douglasii

Potentilfa pennsy/vanica

Poa pratensis

P. sandbergii

Prunus virgimana

Psoralea argophylla

Pseudotsuga menziessii

Psoralea tenuiflora

Puccinellia nuttalliana (airoides)

Ratibida columnilera
Rhus trilobata
Ribes ssp.
Rosa arkansana
Rorippa islandica
Rosa ssp.
Rosa woodsn
Rumex ssp.

Salix amygdaloides

S interior

S rigida var. watsonii

Salicornia rubra

Sarcobatus vermiculatus

Scirpus amencanus

S. ssp.

Schedonnardus pamculatus

Scirpus validus

Senecio canus

Selaginella densa

Shepherdia argentea

Sisymbrium altissimum

Sitamon hystrix

Sonchus arvensis

Solidago gigantea

S. missouriensis

Sphaeralcea coccinea

Spartina gracilis

Stipa comata

S viridula

Suaeda fruticosa

S occidentalis

Symphoncarpus occidentalis

Taraxacum officinale

Thlaspi arvense

Thelasperma subnudum (marginata)

Thermopsis rhombifolia

Townsendia hookeri

Tragopogon dubius

Typha latifolia

Urtica dioica

Vicia americana

Vulpia octollora (Festuca octoflora)

Yucca glauca

Zygadenus pamculatus

Blue flax
Blazing star
Yellow flax
Eastern biscuitroot
Sweep's brush

Hoary aster
Mountain tarweed
Nuttall goldenweed
Yellow sweetclover
Mountain muhly
Leafy musineon

Yellow prickly pear cactus
Clustered broomrape
Indian ricegrass
Suksdorf's broomrape
Pendant pod crazyweed

Whitlow wort

White prairie-clover

Waxleaf penstemon

Purple prairie-clover

Hood's phlox

Kelsey phlox

Threadleaf phacelia

Timothy

Ponderosa pine, yellow pine

Indian wheat

Indian wheat

Great Plains Cottonwood

Douglas' knotweed

Prairie cinquefoil

Kentucky bluegrass

Sandberg's bluegrass

Chokecherry

Silver-leaved scurfpea

Douglas fir

Slender-flowered scurfpea

Nuttall alkaligrass

Prairie coneflower
Skunkbush
Currant, gooseberry
Arkansas rose
Marsh yellowcress
Rose

Wood's rose
Dock

Peach-leaf willow
Sandbar willow
Watson willow
Glasswort, pickleweed
Black greasewood
American bulrush
Bulrush
Tumblegrass

Tule, American great bulrush
Woolly groundsel
Small clubmoss
Silver buffaloberry
Jim Hill mustard
Squirreltail bottlebrush
Perennial sow thistle
Smooth goldenrod
Missouri goldenrod
Scarlet globemallow
Alkali cordgrass
Needle-andthread grass
Green needlegrass
Shrubby seepweed
Slender seepweed
Western snowberry

Dandelion

Fanweed

Thelasperma

Round-leaved thermopsis

Hooker's townsendia

Salsify, goatsbeard, oyster plant

Cattail

Stinging nettle

American vetch
Six-weeks fescue

Yucca, soapweed

Panicled deathcamas

54

APPENDIX ARABLE 3

Vegetation Type Areas of the

Yellow Water Triangle

Differentiated mapping units
habitat type, cover type, or
phase

No. of
acres

No. of
hectares

Percent
of total

1.

ARTR/AGSP H.T.

BOGR Phase

1A

ARTR-BOGR C.T.

2.

ARTR/AGDA H.T.

AGSP Phase

3.

ARTR/AGDA H.T.

SAVE Phase

4.

ARTR/AGSP H.T.

AGSM Phase

5.

ARTR/KOCR H.T.

6

ATDI/GUSA H.T.

7.

ARTR/FEID H.T.

BOGR Phase

8.

ROAR/THRH H.T.

9.

ARCA/AGSM H.T.

10.

SAVE/AGDA H.T.

11.

JUHO/CAHA H.T.

12.

PODE/SYOC H.T.

13.

Scirpus/Carex H.T.

14.

Suaeda/SARU H.T

15.

AGSP/AGSM H.T

16.

MUCU/ANSC H.T

17.

POPR/ARLU H.T.

18.

PIPO/ARTR H.T

19.

PIPO/AGSP H.T.

29,589
7,775

7,440

487

•3,268

373

12

181

9,568

1,744

15,122

1,592

6,258

27

3

18,228

789

•3,268

7,440

7,065

11,983
3,149

3,013

197

1,323

151

5

73

3,875

706

6,124

645

2,534

11

1

7,382

319

1,323

3,013

2,861

17.34
4.70

4.36

.28

1.92
.22
.01

.11

5.61

1.02

8.86

.93

3.67

.02

<01

10.68

46

1.92

4.36

4.14

•In calculating areas, the ARTR/AGSP H.T , AGSM Phase, was combined with the POPR/ARLU H. T because of difficulties
in differentiating on aerial photos.

Grain in sagebrush areas

Grain not in sagebrush areas

Crested wheatgrass in
sagebrush areas

Crested wheatgrass not in
sagebrush areas

Unvegetated bentonite

Dry lake beds

Gravel pits

Alfalfa

928
1,543

3,183

1,572
31
24
18

7,715

376
625

1,289

637

13

10

7

3,125

.54
.90

1.86

.92

.02

.01

.01

4.52

Undifferentiated mapping units,
combinations of habitat types,
cover types, and/or phases

No. of
acres

No. of
hectares

Percent
of total

1, 1A

2, 1A
1,2
1,3

1. 10
1,9
1, 12
1,8
2,3

1,288

4,617

3,938

18

55

29

103

6,244

3,129

522

1,870

1,595

7

22

12

42

2,529

1,267

.75

2.71

2.31

.01

.03

.02

06

3.66

1.83

55

2,6
2. 10

1A, 3

1A, 10

1A, 12

1A, 8

crested wheatgrass, 2

crested wheatgrass, 10

5,3

6,3

10,9

10,12

10.8

9, 12

12,4

12,8

12. 15

12, 16

13,4

8,2

8,4

8, 11

15

18
15, 16
15, 19
1, 1A, 12

1A, 12, crested wheatgrass
1A, 2. 12

1, 2,3

crested wheatgrass, 3, 2
2.4, 17

2, 8, 11
5, 8, 11
8, 11, 15
2, grain
10. alfalfa
12, alfalfa

12, crested wheatgrass

224

3.084

139

362

1,071

538

483

20

334

120

395

1,075

88

473

157

594

179

94

15

514

114

3,241

304

1,034

228

31

861

316

461

120

422

75

56

64

734

30

143

541

292

91
1,249

56
147
434
218
196
8
135

49
160
435

36
192

64
241

72

38

6

208

46

1.313

123

419

92

13
349
128
187

49
179

30

23

26
297

12

58
219
118

.13
1.81
08
.21
64
31
.28
.01
20
.07
.23
.63
05
28
09
35
10
05
01
30
07
1 90
.18
.61
.13
02
.50
.18
.27
07
26
04
.03
04

.43
02
09
32

.17

Totals

170,442

68,975

100

total acreage of land
containing at least some:

Sagebrush

Raw shale

Greasewood

Pine

Agropyron spicatum

No. of
acres

80,174
24,685
23,704
6.885
66.170

No. of
hectares

32.470
9,997
9,600
2,788

26,799

Percent
of total

4700
14 47
13.89
4 03
38 79

56

APPENDIX B
Glossary

Habitat type: A collective area comprising characteristics of soil, climate and topo-
graphy capable of supporting a certain potential (relatively homogeneous) assembly of
plants Ordinarily, the name of the h.t. is derived from the dominant vegetation only, and
not the other parts of the ecosystem.

Cover type: A disclimax vegetation association different from the potential vegetation
occupying an undisturbed h.t. The cover type possesses the same non-vegetal ecological
features as the h.t. from which it is derived.

Association: A particular grouping of plants. It may be climax or disclimax Ordinarily,
a h.t. contains one association with the name of this association also being the name of
the h.t.

Dominant plant: A plant contributing a major proportion of the biomass of an eco-
system and exerting an ecological influence large enough to significantly affect the
success of establishment of other plants

Primary succession: A natural development of both vegetation and soil on primitive
sites potentially leading to the formation of a h.t. The primitive condition of the site may
be a natural situation, such as exposed rock which has not had a chance to weather, or
an anthropogenic situation where man's activities have caused removal and/or alteration
of already existing soil.

Secondary succession: A natural development of vegetation potentially leading to the
formation of a habitat type. It is assumed that a climax vegetation association once
occupied the site but was caused to revert to a serai stage by forces strong enough to
change the vegetation but not the soil

Series: A broad vegetation category based on life form or physiography and species of
dominant plants These are further subdivided into habitat types

Climax: A vegetation association that is fully adapted to a set of site conditions. The
term climax in this paper is assumed to mean topoedaphic climax.

Disclimax: A vegetation association that is not developed to its fullest potential under
natural environmental conditions — as a result of some man-related disturbance. Vegeta-
tion in equilibrium with prehistoric fire and wild ungulate grazing conditions is not con-
sidered as disclimax.

57

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