Study On Grassland Cover Change And Ecosystem Service Trade-off And Synergy In Shiyang River Basin

As the third largest river in the internal water system of the Hexi Corridor in Gansu Province,the Shiyang River Basin’s prosperity and decline are directly related to the survival of the Minqin Oasis downstream and the ecological security of the northwest inland region.Grasslands,as an important component of the ecosystem,not only play a crucial role in maintaining ecosystem stability but also provide numerous services to humans.Nevertheless,grasslands have undergone important changes because of human activities and climatic variation in the past few decades.Therefore,this article combines geographic information technology,R language,geographic detectors,In VEST models,and other techniques with remote sensing interpretation data,meteorological data,soil data,etc.,to explore the spatiotemporal change characteristics of grasslands in the Shiyang River Basin in 2000,2005,2010,2015,and 2020,and further analyze the natural and human factors of grassland spatial changes,clarify the main reasons for the spatial differentiation of grassland coverage,and provide theoretical support for promoting the healthy development of grassland ecosystems.The study also reveals the trade-off and synergy between different service functions and their scale effects on the overall area,administrative divisions,and grassland coverage types,providing guidance for formulating corresponding grassland ecological restoration policies at different scales.The main conclusions are:(1)From 2000 to 2020,the total coverage area of grasslands in the Shiyang River Basin showed a fluctuating downward trend,but the area of high-coverage grasslands increased,and the quality of grasslands gradually improved.In the past20 years,Gulang County has seen the most significant increase in grassland area,with an increase of 73 km~2,while Yongchang County has seen the most significant decrease,with a decrease of 271 km~2.The most significant changes in grassland area in the basin occurred between 2005 and 2010.(2)Natural factors are the main factors affecting the spatial distribution of grasslands,with accumulated temperatures of≥0℃dominating,with a q value of 0.82.Human factors are an important factor affecting the spatial differentiation of grasslands.The impact of policy factors is relatively obvious,and ecological governance projects such as"returning farmland to grassland"have a significant impact on the spatial differentiation of grassland coverage.(3)Although the trends of water conservation,carbon storage,and habitat quality changes in grasslands in the Shiyang River Basin are similar and they show an overall increase,there is a tendency to decline from 2015 to 2020.Soil conservation services showed a decreasing trend first and then an increasing trend.(4)At the overall and administrative division scales,the relationship between ecosystem services is primarily synergistic.Soil conservation services and water conservation services have the largest synergistic area proportion at the overall scale and the largest correlation coefficient at the county scale.Balancing mainly occurred between habitat quality and soil conservation services in Sunan County and Jinchuan District,with correlation coefficients of-0.13 and-0.08,respectively.At the grassland coverage type scale,the trade-off strength between soil conservation services and habitat quality is the highest in the Shiyang River Basin,and it is most significant in high-coverage grasslands.The weak trade-off strength is mainly reflected in the relationship between habitat quality and carbon storage.