COS 27-5 - Spatial assessment on the 5 drivers of biodiversity loss and associations with imperiled biodiversity within continental U.S.

Abstract: The international science community has identified five primary anthropogenic drivers of biodiversity loss: climate change, land- and sea-use change, pollution, over-exploitation, and invasive species. Strategically placed conservation actions that serve to address these threats will be key to safeguarding imperiled species. This study provides a spatial assessment of the potential impact from these primary drivers to better inform conservation measures for mitigating their effect on biodiversity. Here, we describe the distribution and intensity of these five threats separately and cumulatively and highlight where they have spatial overlaps with areas of relatively high biodiversity across the contiguous US. To map these threats, we generated proxies for each one based on publicly available spatial data. To assess the potential exposure intensity of each threat across ecoregions, we measured deviations between ecoregional threat values and national averages. We assessed the potential impact on biodiversity by comparing threat hotspots with areas of high imperiled species richness (by taxonomic group and pooled). Threat and imperiled species richness hotspots were defined as regions with values in the 90^th percentile of the distribution. Overall, 40% of the contiguous US and 44% of areas with high imperiled species richness coincide with at least one threat hotspots. Across 4 taxonomic group hotspots, pollinators had the highest overall overlap with threat hotspots (58%), freshwater invertebrates had the highest overlap with pollution hotspots (21%) and vascular plants and vertebrates had the highest overlap with invasive species hotspots (14% and 15% respectively). We found ecoregional variability in exposure to individual threats such as invasive species and over-exploitation exposure being highest in the Everglades of Florida and climate change exposure being highest in the Temperate Prairies. Soil and water pollution may pose a higher threat in Central and Southeastern Plains while Central Semiarid Prairies may be most impacted by land use change. Our findings may provide spatially explicit guidance for mitigating threats to imperiled biodiversity in the contiguous US. Progress in tackling the biodiversity crisis domestically will require tailored approaches across regions and consideration of the cumulative impacts to biodiversity at different spatial and taxonomic scales.