Plant Community Response to Disturbances in Nebraska Sandhills Prairie.

Prairie ecosystems evolved under various disturbances including periodic burning and soil moving by animals. Given dynamic rainfall patterns, these historic disturbances often resulted in germination and establishment of diverse mixtures of plant species. It is hypothesized that the restoration of prairie through several disturbances will significantly alter plant community composition. Fire, soil disturbance, seed addition, and supplemental water treatments were applied during 2016 and 2017 on south-facing slopes in Nebraska Sandhills upland prairie. Changes in plant community composition were measured through seedling counts, canopy cover estimation, and clipping to estimate above-ground biomass accumulation by plant functional group. Results from 2016 revealed that species richness and annual forb cover were significantly reduced due to spring fire while rhizomatous grass cover was increased. In addition, a shift from litter to bare ground cover was also documented on burned plots. Soil disturbance resulted in certain species-specific negative effects; the establishment of perennial forb species through seed addition was poor; and the application of supplemental water had limited but varied effects on seedling abundance and bunchgrass cover. The fire-induced reduction in weedy annual species such as Canadian horseweed [Conyza canadensis (L.) Cronquist] and increase in rhizomatous grass cover would be desirable from a cattle production standpoint. Further outcomes of this study include a greater understanding of the roles of disturbances in prairie plant communities, and hold implications for management and conservation of rangeland systems into the future.