Abstract: Climate and land-use changes are major drivers of species extinction. However, whether threatened and non-threatened species differ in their responses to these pressures remains unclear. Moreover, the factors inducing the difference are poorly understood. Here, using plant family Theaceae, in which over one-third of species are threatened, we explored the vulnerability of threatened and non-threatened species under future climate and land-use changes, assessed how range size, species current environmental condition, and the magnitude of environmental changes influence the distributional changes of threatened and non-threatened species. The results showed that threatened species were predicted to lose a higher proportion of ranges. Species with limited ranges are more vulnerable to future environmental changes compared to those with larger habitats across threatened and non-threatened groups. The range loss of Theaceae was related to current environmental conditions and the magnitude of future changes, with factors such as temperature, shrubland habitat, and elevation range being important for non-threatened species and soil pH for threatened species. Most non-threatened species were expected to shift towards northern or western regions in the 2070s, whereas threatened species showed a shift trend with multiple directions. Overall, narrow-ranged species were more vulnerable to future changes, and threatened species showed greater projected range loss largely because many of them had restricted current ranges. Our results provide a reference for developing effective conservation strategies, protection of sensitive habitat, enhancement of habitat connectivity, and human-assisted dispersal are urgently needed to minimize negative impacts of climate and land-use changes on Theaceae in China.

Key words: Climate change, habitat loss, land-use change, range shifts, range size, species distribution modelling, threatened species