Managing cheatgrass in rangeland restoration efforts

Authors: Clements, Darin - Charlie; JENKINS, RIXEY - Us Forest Service (FS)

Submitted to: The Progressive Rancher
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2017
Publication Date: 9/7/2017
Citation: Clements, D.D., Jenkins, R. 2017. Managing cheatgrass in rangeland restoration efforts. The Progressive Rancher. 17(8):24-28.

Interpretive Summary: Great Basin rangelands have experienced significant increases in cheatgrass densities and dominance in the past 50 years in habitats that were formerly dominated by big sagebrush and perennial grasses. The increased presence of cheatgrass has resulted in an increase in the chance, rate, spread and season of wildfires. With each passing wildfire season more and more habitats are being converted to cheatgrass dominance resulting in the loss wildlife habitat and grazing resources. The ability of resource managers and land owners to successfully restore/rehabilitate these disturbed rangelands is heavily dependent on the tools available to them to combat cheatgrass invasion. Grazing animals are a tool that University Nevada Range Professor Barry Perryman is investigating. Using 800-1200 cattle on a 7,000 acre pasture, Dr. Perryman is investigating the effect of fall grazing (November 1-30th) on cheagtrass carry-over fuel as well as any reductions in cheatgrass seed bank densities. Fall grazing has significantly reduced fuel loads and seed bank densities, although the remaing fuel loads on average to abbove-average years are still in the dangerous zone. Cheatgrass seed banks are also reduced, yet the remaining density of cheatgrass in the seed bank is enough to ensure coninued dominance. The combination of fall grazing with other range improvement practices is worth future efforts in the battle to reduced cheatgrass dominance. The USDA, Agricultural Research Service is conducting experiments using pre-emergent herbicides to control cheatgrass densities and combine this weed control effort with the seeding of long-lived perennial grasses. The establishment of long-lived perennial grasses is the best known method to suppress cheatgrass densties and associated fuels. USDA-ARS results have successfully reduced cheatgrass by as much as 99.4% and increased seeded seedling emergence and establishment by more than 70% in initial results. Aggressive and effective weed control practices, as experienced when properly applying pre-emergent soil active herbicides, is to establish long-lived perennial grasses that have the inherent potential to germinate, emerge, establish and persist in a given habitat under arid conditions and in the face of competitive species such as cheatgrass. The establishment of long-lived perennial grasses will suppress cheatgrass, decrease the chance, rate, spread and season of wildfires which will allow succession to take place and be beneficial to all multiple uses of Great Basin rangelands.

Technical Abstract: The accidental introduction and subsequent invasion of cheatgrass (Bromus tectorum) onto millions of acres of Intermountain west rangelands has significantly affected the ability of resource managers and land owners to effectively restore or rehabilitate disturbed rangelands. The Nevada Section-Society for Range Management held a tour in northeastern Nevada that focused on management options to restore/rehabilitate former big sageberush (Artemisia tridentata)/bunchgrass communities now dominated by cheatgrass. Dr. Barry Perryman, University Nevada Range Professor, has been researching the effects of fall grazing on cheatgrass fuels reduction in Boulder Valley in the recent past. Barry presented that in the past decade or so, new tools developed for the management of invasive annual grasses in the Great Basin have been both refined and introduced. The precise combination of chemical fallow (herbicides) and seeding with both introduced and native deep-rooted perennial grasses and half-shrubs like ‘Immigrant’ forage kochia have provided great successes on many ecological sites and topographies. Likewise, grazing cheatgrass in the fall and early winter months has demonstrated that it can be managed in such a way as to reduce carryover fuels into the next year’s fire season, while simultaneously reducing its ability to dominate sites that still have a perennial grass component in the plant community. Managing cheatgrass through the use of dormant season grazing has been very successful at a scale of thousands of acres in both Nevada and Oregon where winter dominated precipitation occurs. Given these successes in management tool advances, there has been recognition that annual invasive grasses must be managed as a permanent component of the Great Basin and adjacent areas. For the past fifty years or more, all of our management objectives, goals, and practices have been centered on the perennial grass component of our rangelands. Both rest-rotation and deferred rotation grazing systems (and their various combinations) were designed for managing perennial grasses. However, both of them actually favor the proliferation and dominance of annual grasses. Given our new tool strengths and our new found ability to manage annual grasses at very large scales, it is time that we begin considering and implementing both planning objectives and on-the-ground activities that will allow us to manage annual grasses instead of being victimized by them. It is time to realize and come to admission that many of our shrub dominated communities in the Great Basin no longer have perennial grass understories, instead they have mixed perennial and annual grass understories. With over 50 million acres dominated by cheatgrass, the time of admission is past due. The application of pre-emergent herbicides is another approach that was presented by USDA, Agricultural Research Service Reno, NV Unit. The application of pre-emergent herbicides effectively reduced cheatgrass by as much as 99.4%, and in combination with a 1-year fallow system and seeding of desirable long-lived perennial grasses has yielded very favorable results. Aggressive and effective weed control practices, as experienced when properly applying pre-emergent soil active herbicides, increases the ability establish long-lived perennial grasses that have the inherent potential to germinate, emerge, establish and persist in a given habitat under arid conditions and in the face of competitive species such as cheatgrass. The establishment of long-lived perennial grasses will suppress cheatgrass, decrease the chance, rate, spread and season of wildfires which will allow succession to take place and be beneficial to all multiple uses of Great Basin rangelands.