The impact of climate change on the distribution of Castanopsis (Fagaceae) species in south China and Indo-China region

Abstract

Forests are already and will continue to experience a rapid and extreme change in climatic conditions in the future. The distributions of forests are expected to shift northward and to higher altitudes based on the results of species distribution modelling (SDM). Although SDM is criticized for lack of biotic interactions and natural migration mechanisms, it is still an important tool for understanding the influence of climate change on forest distributions at a landscape scale. We hypothesize that based on extant forest cover, distribution of protected areas and understanding on seed dispersal mechanisms, the suitable range of forest tree species will decline, and certain species might be driven to extinction in the absence of suitable space for migrations in a rapidly changing climate. To assess this scenario, we modelled the current and future potential distribution of 18 Castanopsis species in Asia using MaxENT. Mild (RCP-4.5) and severe (RCP-8.5) climate change scenarios from 17 climate change models were assessed. Three groups of current Castanopsis distribution were identified and they responded differently under climate change. One-third of the species will experience potential range reductions while two-third will have potential range expansions. However, when we overlaid the results with forest cover and protected area coverage, range expansions are unlikely to happen due to fragmented forest cover and lack of efficient seed dispersal mechanisms. Natural species migrations and local adaptation are not likely to happen for Castanopsis and therefore immediate adaptive strategies should be considered in forest management. This situation was particularly severe in the marginal tropical zones across coastal South China and the Northern Indo-China region.