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CAN ANNUAL RANGELANDS BE
CONVERTED AND MAINTAINED AS
PERENNIAL GRASSLANDS THROUGH
GRAZING MANAGEMENT?
Kenneth D. Sanders
ABSTRACT
Essentially three options are available for the management
of annual rangelands: (a) management as an annual rangeland; (b) conversion to a perennial rangeland through grazing management; and (c) conversion to a perennial rangeland by reseeding. The second option is most desirable-if
it is feasible. Evidence suggests that annual rangelands in
higher precipitation zones can be converted through grazing management, providing there are suffzcient perennial
plants present as a seed source. However, in the drier annual rangelands, the preponderant evidence indicates little
chance of conversion through grazing management.
INTRODUCTION
Cheatgrass (Bromus tectorum) and medusahead (Taeniatherum asperum ) dominate several million acres of rangelands in southern Idaho and adjacent States. There are
also millions of acres of annual grasslands in California.
Much of this area has been dominated by annuals most
of this century. Many rangeland management plans in
effect in Idaho have the objective of improving low-seral
range (cheatgrass) to high-sera! bluebunch wheatgrass
<Elytrigia spicata) or Stipa sp., etc., in a few cycles of a
grazing system, with, of course, a 30, 50, or 70 percent reduction in livestock numbers. Is this a realistic objective?
SEVERAL VIEWS
In describing the valley grasslands of California, Heady
(1977) stated that ecologists should recognize that species
labeled as "introduced" and "alien" cannot be removed and
perhaps not even reduced from their present state under
any known ra ngeland management practice. Laycock
(1991) discussed the concepts of stable states and thresholds of range condition on North American rangelands. Although not new concepts, they have only recently received
much attention in U.S. range literature and discussions.
Laycock points out that it is important for range managers
to recognize that multiple steady states exist for many vegetation types, such as cheatgrass rangelands in southern
Idaho. Under our current range condition model, many assume that a reduction in grazing pressure and improved
P~per presented at the Symposium on Ecology, Management, and RestoratiOn of Intermountain Annual Rangelands, Boise, 10, May 18-22, 1992.
K.enneth D. Sanders is Professor, Department of Range Resources, University of Idaho, P.O. Box 1827, Twin Falls, ID 83303·1827.
412
grazing management will result in range improvement.
However, in a stable lower successional state, range condition normally will not respond to change in grazing or
even to no grazing. Friedel (1991) suggested that once a
threshold is crossed to a more degraded state, improvement cannot be obtained on a practical time scale without
a much greater intervention or management effort than
simple grazing control.
Using the California annual grasslands as one example,
Johnson and Mayeux (1992) offer the viewpoint that no
special significance should be attributed to the label "native" when looking at ecological plant performance. They
suggest the evidence they present is "contrary to a common
assumption that the dominance of undesirable plants on
rangelands always serves as evidence of overgrazing by
livestock and that an elimination or reduction in grazing
pressure will result in the reduction of undesirable species
and a return to 'climax' species composition."
In the higher precipitation zones (14 inches plus) in
the Intermountain Region, there is some evidence that
cheatgrass rangelands can be reclaimed by native perennial grasses, providing there is a seed source. Even in
this precipitation zone, my personal observation has been
that the conversion seldom occurs without some means of
reducing the annual grass competition (herbicides, fire,
heavy spring grazing). There is little evidence that annual
rangelands below 12 inches precipitation can be successfully converted to perennial grasslands through grazing
management alone. Laycock (1991) and Heady (1977) both
point out that there is no known grazing system that will
accomplish this feat alone. In fact, failure is more the rule
than success in converting cheatgrass rangelands in southern Idaho to perennial grasses, even when burned and
seeded to competitive grasses such as crested wheatgrass
(Agropyron desertorum, A cristatum).
Why is it so difficult to convert annual grasslands to
perennial grasslands? Laycock (1991) gave the following
reasons for "suspended stages" such as cheatgrass rangeland: dominance by a highly competitive species or lifeform; long generation times of the dominant species; lack
of seed or seed source; specific physiological requirements
that limit seedling establishment except at infrequent intervals; climatic changes; restriction of natural fires or increase in frequency of fires; and others.
In his presentation on medusahead, Dr. Min Hironaka
stated that squirreltail grass (Sitanion hystrix) is the only
native perennial grass he knows of that can compete with
medusahead (see Hironaka, these proceedings). Hironaka
and Tisdale (1963) studied the Piemeisel exclosures in
southern Idaho. While they found squirreltail possessed
the ability to convert cheatgrass ranges to a perennial cover,
conversion requires {1) an ample and mobile seed supply of
the perennial species; (2) that the perennial species have
an inherent ability to withstand cheatgrass competition as
a seedling; and (3) that the perennial seedlings be protected
from damage by rabbits as well as livestock. I would add
to that list protection from insects such as grasshoppers.
grazing management alone, such as a rest-rotation grazing
system, if the following conditions are met: (1) an adequate
seed source of the desired perennial(s); (2) no large populations of rabbits, grasshoppers, or Mormon crickets; and
(3) no extended drought. Do not expect the conversion to
occur in just a few years.
Below the 12-inch precipitation zone, either (1) manage
as an annual rangeland and quit worrying about using only
50 percent of the current year's growth; or (2) burn, spray,
or disk in the fall, reseed with Hycrest crested wheatgrass
(don't waste money on anything else) and hope for a wet
spring.
THE OPTIONS
Essentially three options are available for managers of
annual rangelands: (a) management as an annual rangeland; (b) conversion to a perennial rangeland through manipulation of grazing management; and (c) conversion to
a perennial rangeland by reseeding. The first option is
ecologically unacceptable to some and provides a less reliable forage base. The third option may not be economically
feasible and is sociologically unacceptable to some if introduced species are used. Most users and managers of annual
rangelands would opt for conversion to perennial rangelands if ecologically and economically feasible.
The question is-under what condition is it reasonable
to expect to convert an annual grassland to a perennial
grassland in southern Idaho? There is no magic formula
to answer the question, but I will make the following suggestions. First, get as many knowledgeable people together
as you can, including the livestock permittee(s), get out on
the site to be discussed and make a group decision.
In the 14-inch and above precipitation zones, you might
consider trying to convert to a perennial grassland through
REFERENCES
Friedel, M. H. 1991. Range condition assessment and the
concept of thresholds: a viewpoint. Journal of Range
Management. 44(5): 422-426.
Heady, Harold F. 1977. Valley grassland. In: Barbour,
M. E.; Major, J., eds. The terrestrial vegetation of
California. New York: John Wiley and Sons: 491-514.
Hironaka, M.; Tisdale, E. W. 1963. Secondary succession
in annual vegetation in southern Idaho. Ecology. 44(4):
810-812.
Johnson, Hyrum B.; Mayeux, Herman S. 1992. Viewpoint:
a view on species additions and deletions and the balance of nature. Journal of Range Management. 45(4):
322-333.
Laycock, W. A 1991. Stable states and thresholds of range
condition on North American rangelands: a viewpoint.
Journal of Range Management. 45(4): 427-433.
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