Ecosystem Services Assessment And Its Influencing Factors In Xiaoajiang Basin Of Yunnan

Xiaojiang Basin is located in the southwest karst area in China,which is the key area of the national rock desertification comprehensive treatment project and the ecological security barrier.As a typical faulted basin,where the basin-mountain terrain changes strongly,the climate contrast is large,the groundwater level is buried deep,the water and soil resources are not matched,and the vegetation site conditions are poor,a series of resource and environmental problems,such as water and soil loss and rocky desertification,have seriously affected the ecosystem service function and social sustainable development,due to the unreasonable human activities.It is important to understand scosystem service mechanisms and analyse the spatiotemporal patterns of ecosystem services under the various interferences,for the maintenance and improvement of regional ecosystem services and sustainable development of human welfare.For this purpose,based on ArcGIS,Xiaojiang Basin was selected as a case to evaluate the temporal and spatial vibration characteristics of ecosystem services and identify the driving forces.The preliminary conclusions are listed as bellowed:(1)The total output and unit area output of agricultural product in Xiaojiang Basin were as follows:2008a(1.62?10~5t and 2.997t/mu),2010a(1.90?10~5t and 4.257t/mu),2013a(2.41?10~5t and 3.834t/mu),2016a(2.61?10~5t and 3.094t/mu).The total output of agricultural products showed a gradual increase trend.The output per unit area increased first and then decreased,and the agricultural production service function increased.The agricultural production service function of different landforms was deposition plain region(3.633t/mu),karst platform and valley region(3.545t/mu),karst mountain region(3.490t/mu),peak cluster-depression region(3.458t/mu)and karst canyon region(3.303t/mu).The cultivated lands are mainly distributed in the deposition plain region and karst platform and valley region with lower elevation and less terrain.The degree of rocky desertification is aggravated,resulting in the reduction of soil quality,water resources were reducted,crop growth environment was threatened and agricultural production service function was declined.(2)The total carbon storage in Xiaojiang Basin was as follows:1982a(1.48?10~7t),2003a(1.48?10~7t),2016a(1.75?10~7t).The carbon storage showed a trend of a significant increase after a slow decrease.From high to low,the carbon storage of different landforms were karst canyon region,karst mountain region,karst platform and valley region,deposition plain region,peak cluster-depression region.Photosynthesis and karst carbon sinks are the main sources of carbon storage in the study area,which are affected by factors such as vegetation coverage,rainfall,temperature,and light.The karst canyon region and karst mountain region with higher altitudes and high vegetation coverage are the main areas of carbon storage.The area of rocky desertification was enlarged,the vegetation coverage was reduced,resulting in the reduction of carbon flux,and the carbon storage capacity was reduced.In addition,the average carbon flux of rainy and dry season was 9.03 t/(km~2·a)and 6.88 t/(km~2·a)respectively,which indicated the carbon sequestration capacity of the rainy season was higher than that of the dry season,reflecting the temperature and rainfall contributing to the increase of carbon sequestration.(3)The average habitat quality index of Xiaojiang Basin in 1982,2003 and 2016 was as follows:3.761,3.669 and 2.893,the quality of habitat continued to decline.Compared with 2016 and 1982,the area of habitat degradation(65.86%)is significantly larger than the growing area(14.67%),and the ecological environment was deteriorated.From high to low,the degree of habitat degradation of different landforms were deposition plain region,karst platform and valley region,peak cluster-depression region,karst mountain region,karst canyon region.The deposition plain region and karst platform and valley region with lower elevation and vegetation index were subject to frequent disturbances,the habitat quality was relatively poor.The karst canyon region and karst mountain region with more rainfall and higher vegetation index satisfied the conditions required for vegetation growth and developmet.The area of rocky desertification was enlarged,the vegetation coverage was reduced,the ecological environment wass deteriorating,and the habitat quality was degraded.(4)The deposition plain region and karst platform and valley region are the main agricultural production areas in the basin.The karst canyon region and karst mountain region are the main carbon storage and habitat quality functional areas.Agricultural production areas should focus on protecting cultivated land,improving the agricultural ecological environment,and vigorously developing agricultural production.Forest protection measures should be implemented in the karst canyon region and karst mountain region.At the same time,monitoring and forecasting should be done well,and soil erosion control projects should be done well.