Grasshopper (Insecta: Orthoptera: Acrididae) assemblages of tallgrass prairie: influences of fire frequency, topography, and vegetation

Abstract

Grasshopper assemblages were sampled by sweep net in native tallgrass prairie at Konza Prairie, Kansas, in 1982 – 1986 to assess the influences of fire, topography, and vegetation on local species composition. Species composition at 38 sites was analysed by ordination (detrended correspondence analysis). Frequency of fire and topographic location were reflected along the first two principal axes, respectively. Grass-feeding grasshoppers were more numerous than forb- and mixed-feeding grasshoppers throughout the prairie, but forb and mixed feeders became relatively more frequent as fire frequency decreased. Local species richness of grasshoppers was greater on sites burned infrequently than on sites burned annually or biennially, and on upland than on lowland sites. Local species richness was positively correlated with local plant species richness and diversity, reflecting in part that local relative abundance of forb-feeding grasshoppers was positively correlated with local relative abundance of forbs. Collectively these results are consistent in suggesting that through their effects on local plant communities, fire frequency and topography are major factors influencing the composition of local grasshopper assemblages in tallgrass prairie.