photo of Bray Beltran
Bray joined the VALE Lab in Fall 2009. More about his research interests in global change ecology can be found here.
Summary of Bray's thesis research
Effects of Climate Change and Urban Development on the Distribution and Conservation of Vegetation in a Mediterranean Type Ecosystem
Climate and land use change are projected to threaten biodiversity over the coming century. However, the combined effects of these threats on biodiversity and the capacity of current reserve networks to protect speciesí habitat are not well understood. The goals of this study were to evaluate the effect of climate change and urban development on vegetation distribution in a Mediterranean-type ecosystem; to identify the primary source of uncertainty in suitable environmental conditions predictions; and to evaluate how well habitat reserves protect future habitat in the Southwest ecoregion of the California Floristic Province under these different predictions. I used a consensus-based modeling approach combining three different species distribution models to predict current and future suitable environmental conditions for 19 plant species representing different plant functional types (PFT) defined by fire-response (obligate seeders, resprouting shrubs), and life forms (herbs, subshurbs). I also examined the response of species grouped by range sizes (large, small). I used two climate models, two emission scenarios, two thresholds, and high-resolution (90m resolution) environmental data to create a range of potential scenarios. I evaluated the effectiveness of an existing reserve network to protect suitable habitat for rare species in light of climate and land use change. The results indicate that the area of suitable environmental conditions for each species varied depending on the climate model, emission scenario, and threshold combination. The suitable environmental conditions for up to four species could disappear from the ecoregion, while suitable conditions for up to 15 other species could decrease under climate change conditions. The centroid of the speciesí suitable environmental conditions could shift up to 440 km. Large net gains in suitable environmental conditions were predicted for a few species. Herbs have a small response to climate change, while obligate seeders could be the most affected as PFT. We predicted the other two PFTs to gain area. Several rare species could lose suitable environmental conditions area inside designated habitat reserves while gaining area outside. Climate change is predicted to be more important than urban development as a driver of habitat loss for vegetation in this region in the coming century. These results indicate that regional analyses of this type are useful and necessary to understand the dynamics of drivers of change at the regional scale and to inform decision making at this scale.