Threats to biodiversity from cumulative human impacts in one of North America's last wildlife frontiers

Land-use change is the largest proximate threat to biodiversity, yet remains one of the most complex to manage. In British Columbia (BC), where large mammals roam extensive tracts of intact habitat, continued land-use development is of global concern. Extant mammal diversity in BC is unrivalled in North America owing, in part, to its unique position at the intersection of alpine, boreal and temperate biomes. Despite high conservation values, understanding of cumulative ecological impacts from human development is limited. Using cumulative effects assessments (CEAs) methodologies, we assess the current human footprint over 16 regional ecosystems and seven large mammal species. Using historical and current range estimates of the mammals, we investigated impacts of human land-use on species persistence. For ecosystems, we found that Bunchgrass, Coastal Douglas Fir and Ponderosa Pine have experienced over 50% land-use conversion; over 85% of their spatial extent has undergone either direct or estimated indirect impacts. Of the mammals we considered, wolves were the least impacted yet all species have reduced ranges compared with historical estimates. We found evidence for a hard trade-off between development and conservation, most clearly for mammals with large distributions and ecosystems that have experienced high levels of conversion. Rather than serve as a platform to monitor species decline, we strongly advocate these data be used to inform land-use planning and to assess current conservation efforts. More generally, CEAs offer a robust tool to inform wildlife and habitat conservation at scale. This article is protected by copyright. All rights reserved