Vegetation management for the maintenance and conservation of butterfly habitats in temperate human-dominated landscapes

Abstract

Many temperate butterfly species occur in habitats where human activities have altered the natural or long-term disturbance regime, and current activities modify the structure and availability of butterfly habitats over several spatial and temporal scales. Indeed, human activities modify key ecological processes sufficiently that the maintenance of some butterfly populations depends on human intervention to provide suitable habitat. Combined changes in historic and current disturbance regimes and human land-use practices necessitate active vegetation and habitat management to conserve and expand many butterfly populations. Efforts to protect temperate butterfly habitats often have resulted in successional changes that reduce habitat suitability. Butterfly habitats commonly deteriorate through a reduced intensity and frequency of long-term disturbance or management patterns that result in smaller and fragmented patches of early successional habitat. Fragmentation of otherwise continuous habitats can result in the forced dependence of a metapopulation structure. Because some butterfly larvae require one or a few host plants or adults are selective for nectar or oviposition sites, habitat management plans that include selection of an appropriate site for subsequent vegetation management activities may enhance conservation efforts. Vegetation management activities within an area can be coordinated to provide a mosaic landscape with habitats suitable for numerous species. Recommended vegetation management strategies vary with plant community type, historic disturbance regime, desired vegetation structure and composition, spatial pattern of habitat patches, land ownership patterns, and economic constraints. Because butterflies respond directly and indirectly to vegetation management and to the mosaic nature of habitat patches within the landscape, management plans must accommodate the constraints of the regional landscape and the spatial and temporal dynamics of the prescribed disturbance or management regime. We review efforts to manage temperate plant communities for butterfly habitat, and discuss general strategies for developing a vegetation management program for butterfly habitats in human-dominated landscapes. A case study of Karner blue butterfly habitat conservation efforts is provided.