Study On The Evolution Of Landscape Pattern And Ecosystem Service Value Response Of Small Watershed In Typical Reservoir Areas In The Upper Reaches Of The Yangtze River

As a comprehensive reflection of regional ecosystems,landscape pattern plays an important role in understanding the evolution of ecosystems.Exploring the evolution law,transformation trend and mechanism of the landscape pattern in typical reservoir areas has important practical significance for improving the regional ecosystem,optimizing the landscape pattern,and achieving sustainable development.Based on the high-definition image data of Google Earth,this paper selects three typical reservoir areas in the upper Yangtze River(Ertan Reservoir Area,Wujiangdu Reservoir Area,and Three Gorges Reservoir Area)as the research object by consulting relevant domestic-foreign literature and field survey data.Spatial analysis tools in Arc GIS 10.2,landscape pattern index in Fragstats 4.2,geographic detectors and CA-Markov model are used to explore the spatial evolution of the landscape pattern transformation and its influence mechanism from multiple perspectives in three typical area.Furthermore,it predicts the situation and evolution of the future landscape pattern,and puts forward some optimization suggestions for the sustainable development of the study area.In general,the results of this study aim to clarify the typical reservoir area's landscape pattern transformation modes and the leading factors affecting its distribution and development,and provide a certain reference value for further improving the sustainable use of land in the reservoir area and improving the quality of the ecosystem.The research results are as follows:(1)The land use types of the three typical reservoir areas are gradually diversified.Among them,forest is the most important landscape substrate,accounting for more than50%of each area.The mutual conversion among the five types of cultivated land,woodland,grassland,garden land and abandoned land is the most obvious.According to the land use transfer and the spatio-temporal evolution characteristics of the landscape pattern in the study area,it can be summarized into three modes,namely,valley's Cultivated fruit conversion type,medium mountainous farmland abandonment type,high mountainous forest land restoration type.(2)The mountainous areas'landscape pattern has transformed under the influence of the construction of large-scale reservoirs,which has prompted the transformation of ecological service functions and enhanced the value of ecological services in the study area.The ecosystem service value of the three reservoir areas showed an overall increasing trend,increasing by 399.32×10~6 yuan,305.97×10~6 yuan,and 106.42×10~6yuan respectively.Among them,the regulation service value changed most significantly,accounting for more than 65%of the total value.The natural ecosystem environment in the study area has improved.In addition,the landscape pattern and ecological service function evolution in different reservoir areas have roughly the same spatial characteristics.That is,intensive agriculture based on orchard and farmland is formed in valleys,while ecological agriculture based on forest,grassland and abandoned land is formed in mountainous hilly areas.(3)The landscape pattern transformation of the typical reservoir area in the upper Yangtze River is the result of the comprehensive effect of many influencing factors,and the two-factor interaction has a stronger influence on the landscape pattern spatial diversity in the study area.In addition to natural factors and human factors,the economic policies such as the farmers'susistence transformation,The Grain for Green Project(GGP),The Ecological Protection Red Line and The Ecological Civilization Demonstration Project have all affected the process of landscape transformation.(4)Research on simulation and prediction of landscape pattern in typical reservoir area.By constructing a CA-Markov model to simulate and predict the evolution of landscape pattern in a typical reservoir area in 2026.The results indicate that forest and cultivated land landscapes remained the most important types of landscape land,abandoned land,grassland and construction land increased continuously,water and unused land increased slightly.The landscape fragmentation has been improved,the shape has become more and more complex,the diversity has increased,the overall layout of the landscape tends to be uniform,and the dominant landscape has a weakening trend.(5)Through the analysis of the evolution law and simulation results of the landscape pattern in typical reservoir areas,this paper further puts forward the following issues and suggestions that must be paid attention to in the development of the reservoir area.The suggestions are as follows:We need to strengthen the protection of land use/cover types with high ecosystem services such as forest,grassland and water areas.Scientifically formulate the overall plan for land use in the reservoir area,refine the pattern of returning farmland in mountainous areas to effectively protect arable land;maintain the existing forest area,and strengthen the comprehensive management of watersheds,and further improve the overall social and economic benefits and land use efficiency of the reservoir area.