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INTRODUCTION: CHEATGRASS
INVASION AND SHRUB DIE-OFF
E. Durant McArthur
.;'·:..
This publication consists of the papers presented at the
sixth symposium in a series devoted to the biology and
management of western wildland shrubs. Its twin foci
are a shrub die-off phenomenon and cheatgrass invasion
into western shrublands. The symposium also included
contributions on shrub establishment, including seed germination; shrub ecosystem ecology and physiology; plant
development and performance for enhancing productivity
in shrub ecosystems; and two field trips. The symposium
featured 51 presentations (Shrub Research Consortium
1989); 45 papers and accounts of the field trips are included
in this proceedings. The previous symposia proceedings
have all been published by the Intermountain Research
Station (Provenza and others 1987; McArthur and Welch
1986; Tiedemann and Johnson 1983; Tiedemann and others
1984; Wallace and others 1989). The Shrub Research Consortium (see inside front cover of this proceedings) sponsors
this symposia series with the objective of facilitating the
spread of knowledge of shrub biology and management.
The presentations of this symposium are divided into
six sections including one for the field trips. The first section on Cheatgrass Invasion and Management on Western
Rangelands documents the continuing invasion of cheatgrass (Bromus tectorum) and other annuals, and presents
results of research to counteract the impacts of cheatgrass
on rangelands (11 papers). The ongoing problem of cheatgrass invasion has been recognized for several decades
(Brotherson and Brotherson 1981; Cottam and Evans 1945;
Mack 1981; Pickford 1932; Piemeisel1951; Young and others 1979). It was cogently recognized by Aldo Leopold in
his "Sand County Almanac" (1949): "It is impossible fully
to protect cheat(grass) country from fire. As a consequence,
the remnants of good browse plants, such as sagebrush
and bitterbrush, are being burned back to higher altitudes
where they are less useful as winter forage . . .. The habitable wintering belt is narrow (and is) ... now fast shrinking under the onslaught of cheat(grass) fires." Leopold
further articulated a problem we are attempting to address,
in part at least, in these proceedings: "There is as yet no
sense of pride in the husbandry of wild plants and animals,
no sense of shame in the proprietorship of a sick landscape.
We tilt windmills in behalf of conservation in convention
halls and editorial offices but on the back forty we disclaim
even owning a lance."
The second section on Shrub Die-off on Intermountain
Rangelands includes eight papers. The shrub die-off
phenomenon is not unique to the recent episodes (Nelson
and others 1989; Pyke and Dobrowolski 1989), or the
E. Durant McArthur is Project Leader and Chief Research Geneticist,
Intermountain Research Station, Forest Service, U.S. Department of
Agriculture, Shrub Sciences Laboratory, Provo, UT 84606.
Intermountain area (Clift and others 1987). However, the
recent die-offs were large in magnitude and coupled with
the recent invasion of cheatgrass and other aggressive,
exotic annuals pose problems not encountered previously.
Cheatgrass is a fire (and other disturbance) climax species
that sustains itself by burning and reburning (or other
repeated disturbance factors), thus eliminating for long
periods much of the native, mostly fire-susceptible competition (Mack 1981; McArthur and others 1988; Piemeisel
1951).
Sections three (eight papers), four (nine papers), and
five (seven papers), deal with aspects of establishing shrubs
on rangelands, ecology and physiology in shrub ecosystems,
and the quality and development of shrubs, respectively.
Work presented in these sections reveals promise in addressing the problems identified in the first two sections
and, as Leopold suggested, "picking up a lance."
The field trips describe two excursions in the Mohave
Desert. Both are instructive. One specifically describes
vegetative changes as a result of aboveground and subterranean nuclear explosions at the Nevada Test Site; the
other details plant community dynamics through space
(elevational and aspect gradients) and time (pack rat middens), and as a result of disturbance (fire).
ACKNOWLEDGMENTS
I thank my Shrub Research Consortium and Intermountain Research Station colleagues and personnel of the Division of Continuing Education at the University of Nevada,
Las Vegas (UNLV) for their help in planning and staging
the symposium, and in the many activities necessary in
preparing the proceedings for publication. In particular,
I thank co-compilers Van Romney, Stan Smith, and Paul
Tueller for their sustained and committed help through the
entire process; Don Bedunah, Jack Carlson, Max Dunford,
Ray Jaindl, Stan Smith, Paul Tueller, Darrell Ueckert,
and Carl Wamboldt for serving effectively as session conveners; Van Romney, Richard Hunter, Phil Medica, Joseph
McAuliffe, and Stan Smith for leading stimulating field
trips; Keith McNeil and his staff at the UNLV Division
of Continuing Education for local arrangements and presymposium publicity; and Stewart Sanderson, Pat Ford,
and Carla Oskoei for key help in processing manuscripts.
The Utah and Idaho State Offices of the U.S. Department
of the Interior, Bureau of Land Management (BLM) and
the Utah Interagency Plant Materials Committee provided
impetus to several lines of research reported in individual
papers of this proceedings. In particular, Utah BLM has
been supportive of shrub die-off research and Idaho BLM
to solutions to the cheatgrass invasion problem through
inter-agency agreements with the Intermountain Research
Station and other institutions.
Provenza, F. D.; Flinders, J. T.; McArthur, E. D., compilers. 1987. Proceedings-symposium on plant-herbivore
interactions; 1985 August 7-9; Snowbird, UT. Gen.
Tech. Rep. INT-222. Ogden, UT: U.S. Department of
Agriculture, Forest Service, Intermountain Research
Station. 179 p.
Pyke, D. A.; Dobrowolski, J. P. 1989. Shrub dieback in
the Great Basin. Utah Science. 50: 66-71.
Shrub Research Consortium. 1989. Abstracts, Sixth
Wildland Shrub Symposium: cheatgrass invasion,
shrub-dieoff, and other aspects of shrub biology and
mangement. Provo, UT: Shrub Research Consortium.
29p.
Tiedemann, A R.; Johnson, K. L., compilers. 1983.
Proceedings-research and management of bi tterbrush
and cliffrose in western North America; 1982 April
13-15; Salt Lake City, UT. Gen. Tech. Rep. INT-152.
Ogden, UT: U.S. Department of Agriculture, Forest
Service, Intermountain Forest and Range Experiment
Station. 279 p.
Tiedemann, A. R.; McArthur, E. D.; Stutz, H. C.; Stevens,
R.; Johnson, K. L., compilers. 1984. Proceedingssymposium on the biology of Atriplex and related
chenopods; 1983 May 2-6; Provo, UT. Gen. Tech. Rep.
INT-172. Ogden, UT: U.S. Department of Agriculture,
Forest Service, Intermountain Forest and Range Experiment Station. 309 p.
Wallace, A.; McArthur, E. D.; Haferkamp, M. R., compilers. 1989. Proceedings-symposium on shrub ecophysiology and biotechnology; 1987 June 30-July 2; Logan,
UT. Gen. Tech. Rep. INT-256. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain
Research Station. 183 p.
Young, J. A.; Eckert, R. E., Jr.; Evans, R. A. 1979. Historical perspectives regarding the sagebrush ecosystem.
In: The sagebrush ecosystem: a symposium; 1978 April
27-28; Logan, UT. Logan, UT: Utah State University,
College of Natural Resources: 1-13.
REFERENCES
Brotherson, J.D.; Brotherson, W. T. 1981. Grazing impacts
on the sagebrush communities of central Utah. Great
Basin Naturalist. 41: 335-341.
Clift, D. K.; Semple, W. S.; Prior, J. C. 1987. A survey of
bladder saltbush (Atriplex vesicara Heward ex Benth.)
dieback on the Riverine Plain of South-eastern Australia
from the late 1970s to 1983. Australian Rangeland Journal. 9: 39-48.
Cottam, W. P.; Evans, F. R. 1945. A comparative study
of the vegetation of grazed and ungrazed canyons of
the Wasatch Range, Utah. Ecology. 26: 171-181.
Leopold, A. 1949. Oregon and Utah, cheat takes over. In:
A Sand County almanac. New York: Oxford University
Press: 154-158.
Mack, R. R. 1981. The invasion of Bromus tectorum L. into
western North America: an ecological chronicle. AgroEcosystems. 7: 145-165.
McArthur, E. D.; Blauer, A. C.; Sanderson, S. C. 1988.
Mule deer-induced mortality of mountain big sagebrush.
Journal of Range Management. 41: 114-117.
McArthur, E. D.; Welch, B. L., compilers. 1986.
Proceedings-Symposium on the biology of Artemisia
and Chrysothamnus; 1984 July 9-13; Provo, UT. Gen.
Tech. Rep. INT-200. Ogden, UT: U.S. Department of
Agriculture, Forest Service, Intermountain Research
Station. 398 p.
Nelson, D. L.; Harper, K. T.; Boyer, K. C.; Weber, D. J.;
Haws, B. A.; Marble, J. R. 1989. Wildland shrub dieoffs
in Utah: an approach to understanding the cause. In:
Wallace, A.; McArthur, E. D.; Haferkamp, M. R., compilers. Proceedings-symposium on shrub ecophysiology
and biotechnology; 1987 June 30-July 2; Logan, UT.
Gen. Tech. Rep. INT-256. Ogden, UT: U.S. Department
of Agriculture, Forest Service, Intermountain Research
Station: 119-135.
Pickford, G. D. 1932. The influence of continuous heavy
grazing and of promiscuous burning on spring-fall ranges
in Utah. Ecology. 13: 159-171.
Piemeisel, R. L. 1951. Causes affecting change and rate of
change in a vegetation of annuals in Idaho. Ecology. 32:
53-72.
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