Long-term harmful effects of crested wheatgrass on Great Plains grassland ecosystems

Abstract

Invasions by exotic plants are occurring at an increasing rate and are considered a serious threat to both agricultural systems as well as native communities (Drake et al. 1989). Many of the most harmful exotics in North America were introduced intentionally (Ruesink et al. 1995, Williams 1980). Exotic plants such as tamarisk ( Tamarix spp.), Russian olive ( Elaeagnus angustifolia ), purple loosestrife ( Lythrum salicaria ), African lovegrasses ( Eragostis lehmanniana, E. curvula ) and smooth bromegrass ( Bromus inermis ) were originally brought to North America for agricultural or horticultural purposes but have displaced native species and threaten biological diversity of native communities (Malecki et al. 1993; Robinson 1965; Romo and Grilz 1990; Bock et al. 1986; Shafroth et al. 1995). Many Eurasian grasses have been intentionally introduced throughout temperate North America, primarily for hay and pasture. The most commonly planted exotic grass in western North America is crested wheatgrass ( Agropyron cristatum, A. desertorum ). There are between 15 and 26 million acres of crested wheatgras on this continent (Holchek 1981; Rogler and Lorenz 1983). The conversion of native priarie to crested wheatgrass primarily occurred after the drought of the late 1920s and 1930s when large areas of marginal cropland were abandoned and then seeded with non-native …