Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 4, 2005
Publication Date: May 18, 2005
Citation: Young, J.A., Clements, C.D. 2005. Ecology of cheatgrass. In: Proceedings of the 6th Western States and Provinces Deer and Elk Symposium. 6:6-19. Interpretive Summary: Cheatgrass (Bromus tectorum) is an invasive annual grass that originated in Eurasia, and has invaded millions of hectares of Intermountain rangelands. Cheatgrass increases the chance, rate, spread, and season of wildfires. Cheatgrass also germinates earlier and out competes our native perennials for moisture. The combination of this has resulted in millions of hectares of formerly big sagebrush/bunchgrass communities to be converted to cheatgrass dominance. The loss of shrub communities has exacerbated the decline of mule deer herds throughout the west. Cheatgrass truncates succession by out competing native perennial grasses for moisture, perennial grasses are critical in suppressing cheatgrass. This paper provides insight into the ecology, control, and dangers of cheatgrass in Intermountain Area habitats.
Technical Abstract: Cheatgrass (Bromus tectorum) is an invasive, exotic annual grass that during the 20th century revolutionized the ecology of Intermountain Area rangelands. It accomplished this biological revolution in two ways. First the seedlings of cheatgrass are extremely competitive for soil moisture. They out compete the seedlings of most native perennial plants and especially the seedlings of native perennial bunchgrasses. Secondly, the early maturing, fine textured and occasionally very abundant herbage of cheatgrass increases the chance of ignition and the rate of spread of wildfires. These conditions prevail frequently enough among years, that the return interval between wildfires is greatly shortened. This results in plant succession being truncated to continued dominance by cheatgrass and associated exotic annuals. The frequently occurring wildfires completely eliminate woody species from vast areas of rangeland. Even the non-sprouting, landscape characterizing big sagebrush (Artemisia tridentata) has been eliminated in some areas by cheatgrass fueled fires. Cheatgrass provides the continuity of fuels to enhance the spread of fires from shrub to shrub. Native perennial grasses mature in late August and September. Cheatgrass matures in June, extending the wildfire season into the hottest months of the summer. In order to biologically suppress cheatgrass you must re-establish perennial grasses in the herbaceous layer. In order to establish such grasses some form of mechanical or herbicidal weed control is necessary. The seedlings of most native perennial grasses cannot compete with cheatgrass. Introduced grasses such as crested wheatgrass (Agropyron desertorum [Fisher] Schultz) have proven much more successful in revegetating areas infested with cheatgrass. Big sagebrush will invade crested wheatgrass seedings and eventually suppress or eliminate the perennial grass without recurrent fires.