Butterfly community composition and oak woodland vegetation response to rural residential development

Abstract

Conservation of biodiversity on private lands has become increasingly important, particularly in regions where most of the land is privately owned. This study examined the effects of rural residential development on the oak woodland butterfly community in central California, U.S.A. We sampled butterflies on 26 8-ha sites that spanned a range in development intensity from sites containing small 0.4 ha (1 acre) parcels and highly modified vegetation, to sites contained within parcels greater than 81 ha (200 acres) that were characterized by substantial amounts of undeveloped oak woodland. The percent area of oak woodland vegetation was positively related to parcel size across the range of parcel sizes observed. The numbers of hostplant-specialist butterfly species and univoltine butterfly species were positively correlated with the percent area of oak woodland at a site, while the numbers of multivoltine and hostplant generalist species were higher at sites with smaller parcel sizes and lower percent area of oak woodland vegetation. These trends represent a shift in butterfly species composition from specialist to generalist with loss of historic vegetation and support the notion that zoning for larger parcel sizes may be useful for conserving oak woodland vegetation and its associated biotic diversity.