Fire as a Natural Disturbance to Grasshopper Assemblages of Tallgrass Prairie

Abstract

Effects of spring wildfire on assemblages of grasshopper (Acrididae) nymphs hatching the following summer were studied in native tallgrass prairie in eastern Kansas, USA. Four watersheds (8 sites) of varying fire history were studied; similarities in initial assemblages of early instar nymphs among these watersheds reflected similarities in burning history. Controlled fires were set on 3 watersheds. Burning affected assemblage structure of grasshoppers hatching several weeks later, causing shifts in local species compositions as nymphs matured. Such change apparently resulted because fire adversely affected survivorship of forb but not grass feeding hoppers. Because forb feeders were relatively most common on burned sites that had previously been protected from fire longest (4 yr), change in grasshopper assemblages after fire was particularly pronounced at these sites. Greatest species diversities occurred on sites subjected to intermediate frequency of fire.