Spatial And Temporal Evolution Of Ecosystem Services In The Three Gorges Reservoir Area From 1995 To 2015

Ecosystem services are the various benefits that human beings get from the ecosystem,including supply,regulation,support and cultural services.They are the bridge and link between the ecosystem and the social system.As a typical ecological fragile area,an important ecological barrier area and an ecological economic area in the middle and lower reaches of the Yangtze River,the ecological environment of the Three Gorges Reservoir area is of great significance for human settlements and economic construction.The completion of the Three Gorges Dam and the impounding of the reservoir have led to dramatic changes in the landscape pattern of the Three Gorges Reservoir area,triggered a series of ecological and environmental problems,caused the imbalance of ecosystem structure and function,and affected the ecosystem balance.In the Three Gorges Reservoir area under the background of dramatic changes in landscape pattern,the spatial-temporal changes of ecosystem service functions and their influencing factors are not clear.Therefore,understand the temporal and spatial evolution of the landscape pattern in the Three Gorges Reservoir area,clarify the evolution law of ecosystem service functions,quantitatively evaluate various ecosystem service functions,and explore the impact of different natural / man-made factors on ecosystem service functions,so as to provide scientific basis for the effective management of ecosystem service functions,sustainable development of ecosystems and ecological protection in the Three Gorges Reservoir area.In view of this,this study takes the Three Gorges Reservoir Area as the research area,and studies the spatial-temporal distribution and evolution characteristics of the landscape pattern in the Three Gorges Reservoir Area Based on the spatial analysis method and the principle of landscape ecology;Based on the models of invest(integrated valuation of ecosystem services and trade-offs)and China’s water and soil loss equation,the four ecosystem service functions of the Three Gorges Reservoir area,namely,supply service(grain production),regulation service(water conservation and habitat quality),support service(soil conservation,water purification and carbon storage)and cultural service(recreational potential),are quantitatively evaluated,and their temporal and spatial distribution and evolution characteristics are analyzed,Based on K-means clustering method,different ecosystem service functional areas were divided;Based on the spatial autocorrelation analysis method,the spatial correlation and distribution law of ecosystem service functions are clarified.Based on the analytic hierarchy process,Spearman correlation coefficient and geographic detector method,the importance of different types of ecosystem service functions,the balance and synergy of ecosystem service functions,and the driving mechanism of spatial differentiation of ecosystem service functions are determined.The main conclusions are as follows:(1)the overall landscape pattern of the Three Gorges Reservoir area shows a trend of diversity and complexity,with the decrease of cultivated land and the increase of forest land,construction land and water area;The main landscape types are forest land,cultivated land and grassland,of which the dynamic degree of construction land is the largest,the water area,cultivated land and construction land are violently transformed,and the area from dry land to forest land is the largest.The dynamic degree of construction land is the largest,which is 11.57%,and the dynamic degree of grassland and cultivated land is small.In the landscape pattern index,the diversity and quantity area landscape index showed an upward trend as a whole,while the shape and aggregation landscape index showed a downward trend as a whole.(2)The four ecosystem services in the Three Gorges Reservoir area have high spatial heterogeneity,showing positive spatial correlation;All service functions have been improved,while the function of grain production has weakened.The overall supply and service shows a downward trend,showing a spatial distribution pattern of high in the middle and low in the East and West.The head of the reservoir is a high grain production capacity area.The overall regulation service shows an upward trend,in which the functions of water conservation and carbon storage show a gradual upward trend,while the water purification capacity shows a trend of first increasing and then decreasing.The hinterland of the reservoir is an area with high water conservation capacity,and the pollution of N and P is the most serious,while the head of the reservoir is an area with high carbon reserves.The overall support service functions showed an upward trend,in which soil erosion and habitat quality were improved.Cultural services as a whole showed a significant upward trend.The high recreational potential area is concentrated in the core area of Chongqing urban area,while the low recreational potential area is distributed in the reservoir head and some high-altitude areas in the middle.(3)Each ecosystem service function is closely related to each other,which is embodied in the coexistence of trade-offs and synergies.On the whole,it is dominated by regulation services,support services and supply services,and the driving factor that has the greatest impact on each service function is human activity factor.Water conservation,water purification,food production and soil conservation have strong synergy,while the synergy of water conservation and recreation potential is weak.Among the four ecosystem service functions,regulation service and support service account for 47.4% and 32.9% of the total service functions,while the top three sub service functions are soil conservation,water conservation and water purification,reaching 19.1%,16.6% and 16.5% respectively.The top three driving factors affecting ecosystem services were landscape type,DEM and soil type,and the explanatory factors were 0.556,0.411 and 0.347 respectively;The interaction between human activities and other factors is the most significant to ecosystem service function,and the top three interpretation rates of interaction are: interaction between human activities and natural environment factors,interaction between human activities and socioeconomic factors,and internal interaction between natural condition factors.