| Natural ecosystems provide multiple services and benefits for the entire natural environment,including humans.Humans,as consumers in the ecosystem,use and consume ecosystem services according to their own life needs,such as food supply service provided by forest and food crops.At the same time,humans also have the behavior of transforming the ecosystem.When population and productivity increases,human beings expand the living area and transform the natural surface into urban construction land with impervious materials,resulting in shrinkage of vegetation and soil.As a result,the level of ecosystem services such as food supply,nutrient cycling,and water and soil conservation has been greatly reduced.At the same time,the nutrient and water cycling structure of the ecosystem has been changed,and various ecosystem service functions have been weakened.Due to the integrity of the ecosystem,under the influence of human activities,the stress of urban land expansion on vegetation habitat and soil distribution space will lead to a synergistic decline in ecosystem carbon,water and soil sequestration capacity,food supply capacity and nutrient cycling capacity.In suburban and rural areas,due to the need for food supply in the region,human activities to expand cropland have increased the food supply capacity of the ecosystem,and at the same time led to the decline of ecosystem services provided by forests,especially the water yield service,and resulting in a trade-off of ecosystem services.At present,the impact of human activities on ecosystem services and their relationships and characteristics of the changing process have attracted more and more attention from the academic community,and a large number of related studies have been carried out.Guangdong Province entered a period of rapid urbanization after the reform and opening up in 1978.Shenzhen and Zhuhai in the Pearl River Delta region were designated as special economic zones.Together with the provincial capital Guangzhou,the Pearl River Delta region has become one of the regions with the fastest economic and urbanization development in the country.After 45 years of development,the Pearl River Delta region has formed a stable and highly urbanized cluster.In 2021,Guangdong Province announced the construction of provincial sub-central cities in Shantou and Zhanjiang,forming new rapid urbanization zones in eastern and western wings of Guangdong.Outside of the three major urban development areas mentioned above,due to factors such as lack of good locations and favorable policies,the urbanization level is relatively low,and human activity intensity is lower than that of the three major urbanization areas.Therefore,Guangdong Province has formed an obvious spatial differentiation of urbanization level from the northern mountainous area to the southern coastal area.From the above,this paper takes Guangdong Province as the research area,and based on the calculation of human footprint and four ecosystem services including food supply,carbon storage,water yield and soil conservation from 2000 to 2020,using bivariate spatial autocorrelation and Generalized Additive Model(GAM)to evaluate the spatial clustering patterns between human activity and ecosystem services,describes their influence and nonlinear change process,and identifies the spatial correlation patterns between human activities and the relationships among 4 ecosystem services,so as to explain the impact of human activity on ecosystem services in Guangdong Province.Main conclusions of this paper are as follows:(1)In the measurement of the spatial correlation between human activities and ecosystem services,according to the Moran’s I index,the spatial clustering level between the four ecosystem services and human activities is food supply > carbon storage > soil conservation >water yield.The average bivariate Moran’s I indices in 2000-2020 were-0.401,-0.330,-0.296,and-0.041,respectively,indicating that the four ecosystem services generally show negative spatial correlations with human activities,with the most significant correlation for food supply and the lowest for water yield.Spatially,the local spatial correlations between food supply,carbon storage,soil conservation services and human activity present a dual structure,with the Pearl River Delta,eastern and western Guangdong showing significant high-low cluster,while northern mountainous areas present a low-high cluster.The spatial cluster of water yield and human activity is not significant,and tends to be randomly distributed.(2)In the analysis of the influence of human activity on ecosystem services and the characteristics of the changing process through the generalized additive model,according to the explanation rate of the GAM,this paper reveals that the influence of human activities on the four ecosystem services is carbon storage > food supply > water yield > soil conservation,the average GAM explanation rates from 2000 to 2020 were 64.98%,47.12%,29.10%,and 20.72%,respectively,and the standard deviation of the explanation rates of carbon storage,food supply and soil conservation was less than 10.It shows that human activity has a stable and significant impact on carbon storage and food supply,and a large fluctuation of impact on water yield.The GAM curves reflect that the changes of the four ecosystem services with human activity have obvious nonlinear and staged characteristics.Human activity usually has a greater impact on ecosystem services in the early stage of growth,and then ecosystem services show fluctuations at a low level.At the end of human activity grows,which shows a high level of human activity,ecosystem services present a different trend from the previous two stages.(3)In the spatial correlation analysis between human activity and the relationships among4 ecosystem services,this paper finds that the spatial correlation patch boundaries presented by the relationship among carbon storage,food supply,and soil conservation and human activity are clear.The Pearl River Delta,eastern and western Guangdong all present the LL-HH reverse synergy between the above-mentioned ecosystem services and human activity.Northern mountainous areas present a patchy HH-LL reverse synergy.The relationship between water yield and the other three ecosystem services and human activities presents LL-HH reverse synergy in eastern and western Guangdong,while the core of the Pearl River Delta region presents a HL-HH trade-off between WY-SC and human activity,and the periphery of Pearl River Delta region shows LL-HH reverse synergy.FS-WY,CS-WY and human activity in the Pearl River Delta are in a fragmented LH-HH trade-off state. |
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