Impacts of human activity and climate change on the distribution of snub-nosed monkeys in China during the past 2000 years

Aim: In this article, we analysed two millennia of historical records and environmental information to reconstruct the past distribution and examine the current distribution of snub-nosed monkeys (Rhinopithecus) in China. Location: China. Methods: We applied trend surface analysis (TSA) to document patterns of range shifting in snub-nosed monkeys over time. Random forest was used to study the association between explanatory variables and changes in the distribution of snub-nosed monkeys over the past 2000 years. Results: Our results showed that both the longitude and latitude of snub-nosed monkeys contracted from 0 to 2000 AD. We found that the integrated effects of human population size and changes in temperature in the Northern Hemisphere resulted in a westward and northward contraction of the snub-nosed monkey distributional range. However, the impact of fluctuating temperature was greatest during periods of low human population density (0-1200 AD), whereas from 1200 to 2000 AD, marked increases in human population size in China leading to extensive deforestation, agricultural expansion, hunting, logging and land terracing have had the greatest negative effects. Further analyses highlighted the fact that the rapid expansion of human population density in regions occupied by snub-nosed monkeys between 1700 and 2000 has resulted in the recent extirpation of this primate radiation in eastern, south-eastern and central China. Main conclusions: We examined the interactive effects of human population growth, deforestation, agricultural expansion and climate variation on the past and current distribution of snub-nosed monkeys. Our data provide clear evidence that climate change, human population increase and human activities have differentially affected the viability and distribution of snub-nosed monkey populations over time. In particular, the marked expansion of the human population in China over the past 300 years has resulted in the extinction of Rhinopithecus populations across much of its range.