Spatial variation and predictors of plant species' intrinsic climate sensitivity across the conterminous United States

Understanding how species' sensitivity to climate varies spatially across their ranges and elucidating the important causes is essential for identifying ecologically meaningful geographic units and conservation actions for biodiversity. In this study, we estimated climatic occurrence niches of vascular plants to explore the spatial variation in species' intrinsic climate sensitivity across the conterminous United States. Specifically, we asked if species sensitivity varies more between than within Climate Adaptation Science Center (CASC) regions, delineated according to relative climatic consistency and geopolitical boundaries. We further tested latitude, topographic complexity, and glacial history as potential predictors of intrinsic climate sensitivity, expecting them to jointly explain variation. Sensitivity varied more between than within CASC regions for shared species pools, suggesting the CASC network captures biologically relevant patterns of climate vulnerability. Correlations of sensitivity were strongest among adjacent or latitudinally similar regions, while distant regions showed weaker relationships. Permutation network tests and linear mixed‐effects models further revealed overall regionally structured sensitivity patterns and significant differences in mean sensitivity among CASC regions. Intrinsic climate sensitivity trended lower in higher‐latitude regions characterized by greater topographic complexity and post‐glacial coverage. Together, these findings suggest that historical legacies and regional environmental context shape the large‐scale spatial patterns of species' intrinsic climate sensitivity, and that climatically defined spatial units may provide a useful framework for regionalized biodiversity conservation under climate change.