Rehabilitation of cheatgrass-infested rangelands: concepts

Authors: Clements, Darin - Charlie; YOUNG, JAMES - Retired ARS Employee; Harmon, Daniel - Dan; Blank, Robert - Bob

Submitted to: The Progressive Rancher
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2013
Publication Date: 7/8/2013
Citation: Clements, C.D., Young, J.A., Harmon, D.N., Blank, R.R. 2013. Rehabilitation of cheatgrass-infested rangelands: concepts. The Progressive Rancher. 13(6):30-31.

Interpretive Summary: The introduction and subsequent invasion of cheatgrass (Bromus tectorum) onto millions of acres of Intermountain West rangelands has caused astronomical changes to numerous ecosystems and the multiple uses that depend on healthy and functional ecosystems. This is the first part, of a 3-part series paper, addressing the issue of the rehabilitation of cheatgrass-infested rangelands. Much controversy exists when attempting to manage Great Basin rangelands, especially where cheatgrass is involved. It is not uncommon to have individuals whom believe that livestock do not forage on cheatgrass or that livestock only forage on cheatgrass during a very short green period window. Livestock can utilize cheatgrass as a forage 12 months out of the year, the problem however is that cheatgrass provides many more “empty plate” than “full plate” scenarios due to its sporadic yearly growth/production patterns and its promotion of frequent wildfires. Cheatgrass is very successful on Great Basin rangelands because it has the inherent potential to outcompete native perennial grass seedlings for limited moisture, it produces many more seeds than is needed to sustain the population, has the ability to acquire dormancy and build persistent seed banks, and germinates at a wide range of constant and alternating seedbed temperatures present in the Great Basin. As little as 4 cheatgrass plants/ft² can outcompete our most competitive perennial species, as our testing of 1,000 seed banks resulted in an average of 252 cheatgrass plants/ft². The lack of understanding by agencies and scientists to recognize the abilities of cheatgrass as well as not recognize it as a forage, may very well have exacerbated the problem by conducting restoration practices that were doomed to fail. This was due to seeding species that cheatgrass would outcompete, not applying an active weed control program to decrease cheatgrass competition, building cheatgrass fuels loads, etc. A. C. Hull and P. F. Pechanec, pioneer cheatgrass researchers, published a paper in 1947 titled, “Cheatgrass: A Challenge to Range Research” in which they point out, “…we have tried grazing management for 20 years to aid perennial grasses and have increased cheatgrass seed production and dominance”. Gus Hormay developed Rest Rotation Grazing Systems to be implemented in bunchgrass habitats, not big sagebrush/bunchgrass habitats and definitely not habitats dominated by an annual grass, cheatgrass. These cheatgrass fuel build-ups promote large extensive wildfires that burn critical habitats, and with each passing wildfire season, more and more islands of these critical habitats are consumed in wildfires and converted to cheatgrass dominance, especially in the Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) communities, which is the largest plant community in the Great Basin, followed by the salt desert shrub plant community. Our goal in this part I series is to provide resource managers and land owners with the basic understanding of the problem at hand; the competitive abilities of cheatgrass. In part II we will address “Rehabilitation of Cheatgrass-Infested Rangelands: Application”, lessons we have learned over four decades.

Technical Abstract: The introduction and subsequent invasion of cheatgrass (Bromus tectorum) onto millions of acres of Intermountain West rangelands has caused astronomical changes to numerous ecosystems and the multiple uses that depend on healthy and functional ecosystems. This is the first part, of a 3-part series paper, addressing the issue of the rehabilitation of cheatgrass-infested rangelands. Much controversy exists when attempting to manage Great Basin rangelands, especially where cheatgrass is involved. It is not uncommon to have individuals whom believe that livestock do not forage on cheatgrass or that livestock only forage on cheatgrass during a very short green period window. Livestock can utilize cheatgrass as a forage 12 months out of the year, the problem however is that cheatgrass provides many more “empty plate” than “full plate” scenarios due to its sporadic yearly growth/production patterns and its promotion of frequent wildfires. Cheatgrass is very successful on Great Basin rangelands because it has the inherent potential to outcompete native perennial grass seedlings for limited moisture, it produces many more seeds than is needed to sustain the population, has the ability to acquire dormancy and build persistent seed banks, and germinates at a wide range of constant and alternating seedbed temperatures present in the Great Basin. As little as 4 cheatgrass plants/ft² can outcompete our most competitive perennial species, as our testing of 1,000 seed banks resulted in an average of 252 cheatgrass plants/ft². The lack of understanding by agencies and scientists to recognize the abilities of cheatgrass as well as not recognize it as a forage, may very well have exacerbated the problem by conducting restoration practices that were doomed to fail. This was due to seeding species that cheatgrass would outcompete, not applying an active weed control program to decrease cheatgrass competition, building cheatgrass fuels loads, etc. A. C. Hull and P. F. Pechanec, pioneer cheatgrass researchers, published a paper in 1947 titled, “Cheatgrass: A Challenge to Range Research” in which they point out, “…we have tried grazing management for 20 years to aid perennial grasses and have increased cheatgrass seed production and dominance”. Gus Hormay developed Rest Rotation Grazing Systems to be implemented in bunchgrass habitats, not big sagebrush/bunchgrass habitats and definitely not habitats dominated by an annual grass, cheatgrass. These cheatgrass fuel build-ups promote large extensive wildfires that burn critical habitats, and with each passing wildfire season, more and more islands of these critical habitats are consumed in wildfires and converted to cheatgrass dominance, especially in the Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) communities, which is the largest plant community in the Great Basin, followed by the salt desert shrub plant community. Our goal in this part I series is to provide resource managers and land owners with the basic understanding of the problem at hand; the competitive abilities of cheatgrass. In part II we will address “Rehabilitation of Cheatgrass-Infested Rangelands: Application”, lessons we have learned over four decades.