A cross-taxonomic comparison of insect responses to grassland management and land-use legacies

Abstract

*[We established an experiment to test insect responses to three grassland management treatments: (1) patch-burn graze (burning of spatially distinct patches and free access by cattle), (2) graze-&-burn (burning of entire tract with free access by cattle), & (3) burn-only. Because we expected that land-use legacies could also affect insect abundance and diversity, we evaluated effects of time since fire, grazing history, remnant history (remnant or reconstructed grassland), & pre-treatment vegetation characteristics, which were assumed to be a legacy of prior land-use. Butterflies (Lepidoptera), ants, & leaf beetles (Coleoptera: Chrysomelidae) were surveyed for 3 years to compare their responses to each of these treatments as measured by abundance, richness& species diversity. Our results showed that land-use legacies affected insect abundance, richness, & diversity, but treatments did not. Ant abundance was lower in tracts with a history of heavy grazing. Ant species richness was positively associated with pre-treatment time since fire & vegetation height & negatively associated with pre-treatment proportion native plant cover.]