Regeneration of an endangered plant species endemic to the remote mountain areas: Anthropogenic disturbance matters

The regeneration of plants endemic to remote mountain areas is thought to be relatively unimpacted by human disturbances but rather dominated by abiotic factors, such as geography, climate, and soil. However, because human disturbances are accelerating the extinction of montane plants and the loss of montane forest, this balance may be shifting. Yet, the relative effects of abiotic factors and human disturbances to montane plant regeneration are still largely unclear. Here, we investigated the geographic pattern of regeneration (ratio of seedling and ratio of sprout) and assessed the impacts of abiotic and anthropogenic factors for an endangered montane tree species (Davidia involucrata) across its distribution range in China. We found that the ratio of seedling increased from south to north, whereas the ratio of sprout exhibited an opposite pattern, indicating that under climate warming this species may adopt sprout regeneration as a potential strategy to buffer population contraction at the southern edge. Moreover, while climatic factors were the main drivers of regeneration, anthropogenic factors were also important. Of note, the proportion of pasture land area had a significant positive effect on sprouting, with more sprout regeneration at grazed sites and a higher ratio of sprout at sites with a greater intensity of human disturbance. Our findings suggested that, in addition to climate change, human disturbance is also an important driving factor of the regeneration of plants native to remote mountain areas, and we emphasized that researchers and policymakers should take it into account when protecting endangered plants and managing forest biodiversity.