Bakker, J.D., S.D. Wilson, J.M. Christian, X. Li, L.G.Ambrose and J. Waddington
Semiarid ecosystems such as grasslands are characterized by high temporal variability in abiotic factors, which has led to suggestions that management actions may be more effective in some years than others. Here we examine this hypothesis in the context of grassland restoration, which faces two major obstacles: the contingency of native grass establishment on unpredictable precipitation, and competition from introduced species. We established replicated restoration experiments over three years at two sites in the northern Great Plains in order to examine the extent to which the success of several restoration strategies varied between sites and among years. We worked in 50-yr-old stands of crested wheatgrass (Agropyron cristatum), an introduced perennial grass that has been planted on >10×106 ha in western North America.