Management of invasive non-native species and the establishment of native species are both contingent on climate. Climate may, therefore, impact the effect of invasive species management on surrounding native species. Here we investigate temporal changes over four years in composition, cover and richness of native plant species in native grassland as a result of management of the invasive non-native grass, Agropyron cristatum. Vegetation in study plots was clipped (to simulate grazing) or A. cristatum was selectively treated with herbicide during four years under three levels of water availability to simulate variation in precipitation.
Results/Conclusions
While the cover of Agropyron cristatum decreased in clipped and herbicide-treated plots, especially under dry conditions, the total cover of native species increased in in managed plots, especially under wet conditions. In contrast, species richness decreased in herbicide-treated plots. The response by individual native species varied. Common species such as Bouteloua gracilis increased significantly in clipped plots, especially under wet conditions. Other common native species such as Selaginella densa and Carex pensylvanica did not respond to management, but showed a drastic decrease in dry conditions. Our results suggest that dominant native species of native grassland are promoted by long-term management such as grazing, but may not respond to direct removal of invasive species by the means of selective herbicide. A decrease in precipitation, however, may not directly interact with invasive species management, but may lead to poor results due to slow recovery of native plant species.
