Investigation into Climate Change Effects on carbon and water fluxes, and water use efficiency of the Temperate Grassland Ecosystems in Inner Mongolia of China

Abstract

Abstract The daily gross primary productivity (GPP) and evapotranspiration (ET) in the Xilingol temperate grassland ecosystem of Inner Mongolia, China were simulated during 2003 to 2019 and under future climate change scenarios by the BioGeochemical Cycles (Biome-BGC) model, which was optimized by the system response parameter calibration method (SRPCM), the temporal variations of GPP, ET and WUE (GPP/ET) on multiple time scales were investigated, and the impacts of precipitation and temperature on them were explored. The results revealed: the BIOME-BGC model performed better optimized by SRPCM than by PEST; GPP and ET at annual and seasonal scales all showed an insignificant increasing trend; WUE at annual scale and in growing seasons all showed an insignificant increasing trend with it presenting a slight decrease trend in non-growing seasons; the intra-annual distributions of GPP, ET and WUE were very uneven with the highest GPP and ET appearing in July and the highest WUE in September; annual GPP and ET are more sensitive to the changes in precipitation than in temperature with WUE keeping relatively stable with years; precipitation is a critically controlling factor to GPP and ET in growing seasons and to ET and WUE in non-growing seasons; monthly precipitation exhibited greater influence on GPP, ET and WUE than monthly temperature with the previous month’s precipitation imposing bigger effects on GPP than the current month’s; the combined increase scenarios in temperature and precipitation impose greater impacts on GPP/ET/WUE than the ones only increasing in temperature or precipitation.