Scenarios of future changes in land use, open space, and habitat connectivity around the National Wildlife Refuge System and other protected lands

摘要

Conservation in the face of land use change, a primary threat to biodiversity, requires understanding both the threat changes pose to conservation efforts and the drivers of change. Protected areas, our primary approach to conservation, are often surrounded by land being used for agriculture or houses, which affects their conservation value. Considering current land use and identifying future threats is critical to effective conservation, both within protected areas and without.;My dissertation goal was to assess threats to the U.S. Fish and Wildlife Service National Wildlife Refuge System (NWRS) from land use change. To do this, I first quantified land use change around refuges under different economic policy scenarios. Second, I quantified and projected housing growth effects on structural habitat connectivity. Third, I projected changes in functional habitat connectivity under land use and climate change scenarios for Blanding's turtle, a species with limited dispersal ability. .;My primary result was that there will likely be significant land use change regardless of economic policy scenario. However, differences among scenarios were minor with the exception of restricting urban growth, which had stronger effects than other policies and preserved natural habitats as well as a policy specifically designed to preserve natural habitats. In addition, relying on habitat connectivity to mitigate the effects of global change is unlikely to be broadly effective because urban use has already precluded restoring connectivity for many refuges. In both of these cases, land use change patterns were strongly regional in nature. Finally, climate change had a stronger influence on changes in habitat connectivity than land use change for the Blanding's turtle, which demonstrated a "trailing edge" effect wherein populations at the southern edge of the range lost habitat connectivity more quickly than in the northern part of its range. My findings indicate that a single national policy is not workable without the flexibility to account for regional differences change, that conservation planning should occur at the ecoregional as well as the individual protected area level, and that protected areas managing for a single species should assess the effects of global change on their focal species and conservation goals.