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- Warmer temperatures, more extreme droughts and wet years will directly impact the abundance of plants on Western rangelands, alter the mix of plant species found there and change plant species’ geographic boundaries.
Adler and Compagnoni have conducted experiments to examine what this will mean for range plants, especially cheatgrass — the nemesis of land managers throughout the West.
Cheatgrass (Bromus tectorum) spreads rapidly, degrades the environment and affects soil moisture, plant communities and wildlife. A cool season grass, it germinates in fall and grows during winter and spring. It develops an extensive root system in winter, so by the time other grasses and plants begin to grow; the cheatgrass has usually robbed the top foot of soil of its water.
In early summer, cheatgrass dries quickly, transforming millions of acres into extremely efficient fuel for more frequent wildfires. Those fires wipe out other vegetation, leaving soils unprotected from erosion, but cheatgrass is so resilient that it’s usually the first plant to take root again. Cheatgrass is not yet a problem at higher, cooler elevations, but that could change.
In an experiment conducted at varied elevations in northern Utah, Compagnoni found warmer temperatures improved cheatgrass performance.
“Our historical data showed cheatgrass seems to do best in low snow years and the experiment confirmed that trend,” Adler says. “We expect drier, warmer years with more pronounced mid-winter thaw. It doesn’t take much warming to lose snowpack. Our work suggests these decreases in snowpack will promote the cheatgrass invasion, at least in mid to high elevations.”
Efforts are underway in laboratories across the West to find ways to control cheatgrass, but until an effective method is devised, Adler says agencies may have to budget more money to fight the frequent fires that will accompany cheatgrass expansion.