Assessing the regional climate connectivity based on climate trajectory simulation: A case study of Zhangjiakou City, Hebei Province, China.

Climate change and human disturbances increasingly impede species migration and exacerbate the global biodiversity crisis. However, current research on the fine-scale climate connectivity remained limited and insufficient to effectively guide the construction of climate corridors. With Zhangjiakou in Hebei Province as a case, we employed climate exposure cost, human exposure cost, and minimum cumulative exposure models to simulate climate trajectories from 2004 to 2080, and assessed climate connectivity under compound climate-human stress. The results showed that topographic heterogeneity was the dominant factor driving the spatial variation in exposure costs, leading to compound exposure costs in the study area shifting from high in the south, low in the north to high in the north, low in the south as the species' thermal tolerance threshold increased. Climate connectivity across Zhangjia-kou was generally low. The Bashang Plateau and the Taihang Mountains served as potential source and sink areas for regional species migration, respectively. Meanwhile, human disturbance significantly suppressed climate connectivity, with the Bashang Plateau being the most strongly affected. In the future, species would be expected to migrate mainly along the "Bashang-Taihang Mountains" pathway, but gaps in local climatic niches may restrict species movement. In the future, it is necessary to assess climate connectivity at multiple spatial scales, in alignment with conservation goals and species-specific traits. Finally, we proposed multiple strategies for climate corridor construction, such as adjusting corridor paths along climate gradients and designing corridor widths based on the biological characteristics of species.