Effects of Fire on Grasshopper Assemblages in a Northern Mixed-grass Prairie

Grassland Þres have been shown to inßuence grasshopper community composition and population dynamics, but studies of their effects on rangeland grasshopper assemblages in the northern Great Plains are lacking.This study was designed to examine the effect of a grassland wildÞre on grasshopper community composition and population densities of three grasshopper subfamilies in western North Dakota northern mixed-grass prairie with sampling in paired burned and unburned plots.A rapidly moving Þre occurred in late October 1999, after egg-overwintering grasshoppers had died.Vegetation biomass and nitrogen content of grasses did not differ statistically between burned and unburned plots in 2000.The Þre negatively affected grasshopper population densities the year after the Þre, but species diversity was not affected by the Þre.Much of the reduction in grasshopper population densities was caused by a decline in densities of Gomphocerinae species.Grasshopper subfamily densities did not differ statistically between burned and unburned plots in 2001.Additional research is needed to determine the mechanisms leading to the reduction in Gomphocerinae species densities.