Shifting balance between habitat and climate in boreal biodiversity patterns across space, time and taxa

Climate and habitat are key drivers of biodiversity patterns. However, how they independently and jointly affect species distribution across space, time, and taxa remains poorly understood. Here, we evaluate the relative importance of habitat and climate variables underpinning occurrence and abundance patterns of 503 terrestrial animal species over 20 years and a ~ 1100 km latitudinal gradient in Finland. Habitat composition is the main explanatory variable of biodiversity patterns, with varying importance and uncertainty across taxa, regions, and years, and with effects being partially correlated for many species. Specifically, habitat dominate in importance for butterflies, birds, and small mammals, while both habitat and climate explain the patterns of large mammals and moths. Additionally, patterns between biogeographical regions and years are mainly explained by climate, while habitat explains most variation within regions and years. Further differences emerge among functional groups, as body size, pace of life and specialization modulate the relative importance of habitat and climate. Our findings emphasize that land use is a major force in shaping terrestrial biodiversity, while highlighting its tight connection with climate. Considering functional, spatial, and temporal contexts is thus essential for building effective conservation strategies for biodiversity under global change. Climate and habitat jointly shape species distributions and biodiversity. The authors show that habitat is the main driver of boreal terrestrial biodiversity, while the relative roles of climate and habitat vary by region, year and species traits.