Big Sagebrush Transplanting Success in
CRESTED WHEATGRASS STANDS INTRODUCTION Wyoming big sagebrush (Artemisia tridentata subsp. Wyomingensis) is a dominant shrub species on millions of acres of rangelands throughout the Intermountain West and plays a critical role in the health and diversity of many wildlife species such as sage grouse and mule deer. The accidental introduction and subsequent invasion of cheatgrass (Bromus tectorum) throughout the Intermountain West has truncated secondary succession by providing a fine-textured, early maturing fuel that increases the chance, rate, spread and season of wildfires. Big sagebrush communities that historically burned every 60-110 years are now burning as frequently as every 5-10 years, simply too short of a period of time to allow for the return of this critical shrub species. When cheatgrass moves in, wildfires that destroy many shrubs follow. This scenario has played out all macros in the Intermountain West.
By Charlie D. Clements and Dan N. Harmon
With each passing wildfire season, more and more shrub habitats are converted to cheatgrass dominance (Figure 1). The loss of shrubs has important consequences to wildlife, especially fragmentation of habitat to sensitive species such as sage grouse and wintering mule deer herds, and resource managers often point out their frustration of lack of shrub species in crested wheatgrass seedings. Natural recruitment of Wyoming big sagebrush is well reported, yet the natural recruitment of Wyoming big sagebrush following wildfire is very limited. Wyoming big sagebrush does not re-sprout following wildfires, it does not build persistent seed banks and it does not have an active wind or granivore dispersal system with the vast majority of seed being dispersed within a meter of the shrub. Restoration practices to re-establish Wyoming big sagebrush has largely been met with sub-marginal success, yet the need to restore or rehabilitate
Wyoming big sagebrush has become increasingly important due to extensive losses of sagebrush habitats following the more frequent large catastrophic wildfires. The establishment of deep-rooted, long-lived perennial grasses is the best-known method at suppressing cheatgrass. The introduced crested wheatgrass (Agropyron cristatum) was in initially seeded on a million plus acres in Nevada to provide much needed forage for over grazed rangelands, but was soon recognized to successfully compete with cheatgrass in arid environments as well as competitively suppress cheatgrass and associated fuels (Figure 2). Even though over 1 million acres of Nevada rangelands was seeded to crested wheatgrass, many of those seedings have since returned to shrub dominance to a point where the shrub densities have significantly reduced crested wheatgrass densities and opened the door to increased cheatgrass occurrence in those communities. Even with older crested wheatgrass seedings being increasingly brushed up, there is an increasing demand to diversify more recent crested wheatgrass seedings with desirable species such as big sagebrush. Neil West, retired range Scientist at Utah State University pointed out more than two decades ago that it is important to understand site potential before jumping to conclusions on the length of time that species such as crested wheatgrass would remain dominant on a site. Dr. West pointed out that crested wheatgrass seeded on sites that are represented by the dominance of herbaceous species are more likely to remain crested dominant for some time just as bluebunch wheatgrass would remain the dominant herbaceous species.
Figure 1. Former big sagebrush/bunchgrass community converted to annual grass dominance following catastrophic wildfire. The loss of critical browse species for cover and forage have had significant negative impacts on numerous wildlife species.
14 NOVEMBER/DECEMBER 2021
The Progressive Rancher
On sites that are more shrub dominated such as western and central Nevada, the crested wheatgrass plants would become shrub dominated due to lack of fire and other disturbances (Figure 3). Seeding Wyoming big sagebrush in existing crested wheatgrass seedings has been reported to be largely unsuccessful, therefore transplanting of big sagebrush has become more popular. Most big www.progressiverancher.com
