Abstracts are provided in the language submitted.

Biodiversity is declining across the globe, with climate change and land-use change frequently implicated as primary causes. Understanding the mechanisms behind declines is critical for developing effective conservation and management strategies. Pollinators are an especially important group to understand biodiversity change in, given the ecosystem services that they provide, and bumblebees (Bombus) are a particularly important and beautiful group of wild pollinators. We use a large dataset of bumblebee observations, and geospatial and statistical methods, to relate historic trends (between 1900-1974 and 2000-2018) in local extinction and colonization to concurrent changes in climate and human land use. We investigate the historic effect that protected areas have had on bumblebee biodiversity, and whether they appear to have mitigated declines from climate change and land-use change. We find a likely mechanism of how climate change has driven biodiversity change and introduce a broadly applicable methodology to improve prediction of climate change-related risk. This work implicates the increasing frequency and severity of extreme weather events in pollinator declines, and suggests that the creation and maintenance of microrefugia within landscapes could help slow extirpations. Human land-use is not always associated with declines, suggesting that properly managed human landscapes could have minimal effects on pollinators. Interactions between climate change and land-use change are important, but complex. In the face of this, protected areas are related to lower local extinction risk for bumblebees, especially in very human-dominated areas.

Dr. Peter Soroye