Life history, secondary production, and ecosystem significance of acridid grasshoppers in annually burned and unburned tallgrass prairie

Abstract

Secondary production of the acridid community on Konza Prairie Biological Station, Kansas, was estimated to evaluate its significance to energy and nutrient cycling in annually burned and long-term unburned tallgrass prairie. A drop-trap and vacuum device were used to sample acridids on three watersheds in both the burned and unburned prairies during the 1998 and 1999 growing seasons. Production of common species was estimated using the instantaneous growth method, and consumption and egestion were estimated using ecological efficiencies. Total acridid abundance, biomass, and production estimates showed a trend of higher values on burned than on unburned watersheds during both years with significantly higher biomass and production on burned watersheds during 1998 (P < 0.05). Higher biomass and production on burned watersheds was primarily a result of higher values for graminivorous taxa. Forb-feeder and grass-feeder production was more similar on unburned than on burned watersheds, although responses of individual species varied greatly between the two watershed types and years. Grass-feeders and forb-feeders consumed an estimated 0.4-4.7 g ash-free dry mass (AFDM) m-2 yr-1 of grass and 0.7-2.1 g AFDM m-2 yr-1 of forbs, respectively, depending on watershed type and year. Results indicate that acridids are important in nitrogen cycling. However, their relative importance to energy and nutrient cycling in tallgrass prairie varies with plant responses to burning and may be influenced by ungulate grazing.