May 2014
NR/Rangelands/2014-01pr
Should Ranchers Value Sagebrush? Why We Need Sagebrush Beth Burritt, USU Dept. of Wildland Resources; Thomas Monaco, USDA-ARS, Logan, Utah; and Eric Thacker, USU Dept. of Wildland Resources Big sagebrush (Artemisia tridentata) grows in arid and semiarid areas throughout the Intermountain West. It is a long-lived, slow-growing, evergreen shrub that typically grows 2 to 4 feet in height but can grow to 13 feet. Leaves have three lobes and are blue-gray to gray-green. The shrub is very aromatic due to its terpene content. It is perhaps the most common shrub on western rangelands (West 1979). Yet many ranchers try to rid their land of big sagebrush to increase forage for livestock. Repeated wildfire has killed many big sagebrush plants across the West because big sagebrush doesn’t re-sprout after fire. Sagebrush communities are typically slow to recover after fire. Recovery may take as long as 20 years for sagebrush growing at high elevation to 100 years on low elevation sites (Figure 1). When sagebrush is eliminated from an area, forbs and grasses may increase
Figure 1. Fire return intervals in sagebrush systems without cheatgrass. (Adapted from Knick et al. 2006)
in the short term, depending on their density and whether seeds are present in the soil to produce new plants. However, if invasive annual grasses like cheatgrass are present (Figure 2), they often increase after fire and the removal of sagebrush. The spread of cheatgrass has increased with the increase in wildfire intensity (heat). Fire frequency has increased from every 15–100 years to as often as every 3 years. These fires are eliminating sagebrush throughout the West. Good riddance? Maybe not–big sagebrush has big benefits for plant communities as well as for wildlife and livestock.
Sagebrush Benefits Other Plants The canopy of sagebrush provides a favorable environment for many plants growing in the understory. It also protects grasses and forbs in the understory from overgrazing. Sagebrush plants increase water retention by trapping and holding windblown snow. Contrary to long-standing beliefs, complete removal of sagebrush often negatively affects biodiversity and has few longterm benefits on the productivity of perennial grasses and forbs. Forage production may actually decline when sagebrush is completely removed from rangeland (Tilley Figure 2. Sagebrush invaded by cheatet al. 2006). grass. Wildfire would likely kill the Big sagebrush plants provide
sagebrush resulting in a cheatgrass monoculture. (Photo by Justin Williams)