Abstract: Zoigê is a sensitive region to global climate change and a key ecological barrier for the upper reaches of the Yellow River and Yangtze River in China. However, soil water carrying capacity for vegetation (SWCV) in this area under global climate change is still unclear. We used the Biome-BGC model to simulate water use efficiency (WUE) of typical Hippophae rhamnoides dominated vegetation on four types of sandy land (fixed sand land, semi-fixed sand land, shifting sand land, and exposure sand land) under various climate change scenarios from 2007 to 2021. The SWCV of H. rhamnoides on different types of sandy land was estimated based on the model. The results showed that under different climate scenarios, annual average WUE of H. rhamnoides ranked as exposure sand land > fixed sand land > semi-fixed sand land > shifting sand land. Compared to current climate scenario, WUE was generally lower under future climate change scenarios. Under the scenario with increased temperature and precipitation, WUE was the lowest among all scenarios. SWCV was ranked as fixed sand land > semi-fixed sand land > shifting sand land > exposure sand land under different climate scenarios. Compared to current climate scenario, the SWCV decreased on all types of sandy land under future climate change scenarios. Precipitation and temperature had a coupled effect on SWCV, with precipitation having a greater impact than temperature. By revealing the responses of SWCV on different sandy land types in the Zoigê area to climate change, this study provides guidance for ecological management and restoration of alpine sandy land in the region.

Key words: Biome-BGC model, climatic change, soil water carrying capacity for vegetation, Zoigê