Mesophytic and less-disturbed mountainous habitats are important for in situ conservation of rare and endangered plants

Protecting rare and endangered plants is important for maintaining ecosystem structure and function, conserving biodiversity, and even sustaining national economic growth. However, the effects of habitat characteristics, geographical distribution, and climatic factors on the distribu-tion of rare and endangered plants in China, home to 19.4 % of the world's endangered species, remain unclear. To address this important knowledge gap, we collected information on climate, altitude, habitat, and distribution of rare and endangered plants in China to determine their habitat characteristics, geographical distribution, and the relationships between environmental factors and species density. We found that rare and endangered plants tend to occur in warm, humid, and forested habitats. Mountains, rather than plains, hills, eolian landforms, tablelands, lakes, and glaciers, can provide mesophytic and less-disturbed refuges for rare and endangered plants. In particular, medium and medium high-altitude mountains located in monsoon domi-nated regions with high precipitation, temperature, and humidity provide habitats for species of rare and endangered plants with high density. Our findings highlight the importance for a more explicit consideration of these mountains for in situ conservation of rare and endangered plants.