The Grain for Green Project(GGP)is an important measure for the prevention of sloping farmland and the restoration of natural vegetation.This project has been critical to the restoration of ecological environments in western China.However,the effect of the GGP on freshwater ecosystem services under extreme climates remains unclear.Thus,taking the middle and upper reaches of the Wujiang River Basin in western China as an example,this study assessed the variation of three freshwater ecosystem services(e.g.,water yield,soil retention and nutrient retention)impacted by the GGP under drought stress by employing the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model.In addition,the trade-off/synergistic relationship between three freshwater ecosystem services was analyzed based on the Pearson correlation coefficient.As revealed from the results,the effect of the GGP on the water yield and nutrient retention under drought stress was significantly higher than that on the soil retention.With the increase in the drought degree,the variation rate of the water yield and nutrient retention impacted by the GGP increased,whereas that of the soil retention decreased.The GGP in droughts of different seasons resulted in a significant heterogeneity in the changes of three freshwater ecosystem services.The correlation coefficients between the water yield and soil retention as well as that between the water yield and the nutrient retention increased,and the correlation coefficients declined between soil and nutrient retention under different drought degrees following the GGP.Unlike for the summer drought case,there were no significant changes in the correlation coefficients between three freshwater ecosystem services in spring,autumn and winter droughts.The results suggest that the amount of farmland converted to shrubland should be regulated to reduce the trade-off intensity between freshwater ecosystem services.In addition,food security and ecological environment protection should be balanced during the implementation of the GGP,and the most concentrated distribution region of farmland-to-forest conversion will be the key area of ecological management in the future.

HAN Hui-qing;YANG Jian-qiang;LIU Yue;ZHANG Ying-jia;WANG Jun-wen

College of Architecture and Urban Planning,Guizhou Institute of Technology,Guiyang 550003,China;College of Economics and Management,Guizhou Institute of Technology,Guiyang 550003,China

山地科学学报（英文版）

[1]HAN Hui-qing;YANG Jian-qiang;LIU Yue;ZHANG Ying-jia;WANG Jun-wen-.Effect of the Grain for Green Project on freshwater ecosystem services under drought stress)[J].山地科学学报（英文版）,2022(04):974-986

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