Effects of Management Techniques on Grassland Butterfly Species Composition and Community Structure

Abstract

Semi-natural grasslands are a crucial habitat for many butterfly species and the structure and extent of that grassland often dictates the composition of butterfly communities on the landscape. To understand effects on butterfly communities, we studied the impacts of different management schemes used to maintain semi-natural grasslands, including mowing every 3 y, mowing annually, and continuous summertime grazing. Transect count data were gathered over the 3 summers (2007–2009) in the Southern Appalachian Mountains of western Virginia and North Carolina. Eleven thousand two hundred and four butterfly individuals of 42 different species were documented over the course of the study. Fields with minimal management, being mowed only once every 3 y, had the largest benefit to butterfly communities. Species richness, abundance, and Shannon diversity was significantly higher in these fields. While abundance was not significantly different between annually mowed fields and grazed fields, mowed fields were significantly higher in richness and diversity. The analysis of habitat specialist species revealed minimally managed and mowed fields were higher in abundance and richness than grazed fields. The response of individual butterfly species also showed negative effects of grazing on habitat specialists. Overall, the results suggest a varying response by different groups of species as well as individual species, indicating multiple management techniques are necessary for conserving a wide range of species. Specific techniques can be used in conservation to target specialist groups of butterflies and rare species.