Conversion of Smooth Brome (Bromus inermis) to Switchgrass (Panicum virgatum) on Untilled Prairie in Northwest Iowa

摘要

Since European settlement, vegetation and disturbance regimes in the North American prairies have dramati cally changed. Native tall and mixed-grass prairies once covered a majority of the central and eastern Great Plains region of the United States, but less than 4% of the origi nal 60 million ha of tallgrass prairie remains (Steinauer and Collins 1996). Smooth brome (Bromus inermis) is an introduced cool-season perennial, sod-forming grass that invades both native cool- and warm-season grass lands throughout North America (Dibbern 1947, Wilson 1991, Stubbendieck et al. 1994). The first documented importation of smooth brome to the United States was to the California Agricultural Research Station around 1880 as a cold and drought tolerant forage species (Newell and Keim 1943). In 1897, 12 tons of seed were imported from the Volga River region, divided and sent out to state research facilities across the United States (Dunn 1985). Because smooth brome has become an extremely success ful invasive grass, it is problematic for managers working to restore and conserve native plant communities.