| This dissertation investigates the impacts of urbanization on butterfly diversity in Washington, DC, northern Virginia, and Maryland and the role of butterfly gardens in butterfly conservation. Using weekly butterfly garden surveys from 135 gardens and 4th of July Butterfly Counts from 1990 to 2001, I investigated whether the matrix surrounding suitable butterfly habitat affects the diversity of the species found in this suitable habitat. The hypothesis of this study was that increasing levels of human development and population density in the matrix surrounding butterfly habitat will negatively affect the butterfly diversity found in the habitat. Results of this study indicate that local, not regional, butterfly diversity is negatively affected by increasing levels of human development (rural, suburban, or urban development) surrounding the habitat, but that the matrix is just one factor in generalist species diversity. Other factors include the size of the suitable habitat, the number of nectar plants blooming in the habitat, the use of pesticides in neighboring areas, and linkages to other suitable habitat. These results indicate that butterfly gardens do serve a purpose in butterfly conservation, most likely serving as stepping stones or corridors between larger tracts of habitat. Conservation efforts should include butterfly gardens, but larger tracts of natural habitat with less development or large gardens should also be included in any conservation plan. Future study should: (1) include species with more specific habitat needs than the twelve species used in the butterfly garden study, (2) more closely investigate the effects of pesticide use in neighboring areas, and (3) use mark-release-recapture techniques to study metapopulations in this area. |
