Assessment Of Ecosystem Service Function And Construction Of Ecological Security Pattern In Wangkuai Reservoir Watershed

Scientific assessment of regional ecosystem service function is the basis of rational utilization of natural resources and ecological protection.The Wangkuai Reservoir watershed is located in the Taihang Mountains and is one of the water sources in the upper reaches of the Baiyangdian Lake.Based on the InVEST model,this study analyzed the spatial and temporal characteristics of water conservation,soil conservation,carbon storage,habitat quality and water purification services in Wangkuai Reservoir Basin in 2000、2010 and 2020,and reveal its trade-off and synergy.On this basis,the changes of land use and landscape pattern,their impacts on ecosystem services and their relationships were analyzed.Finally,using ordered weighted average operator(OWA)to set different scenarios,the priority protection area of ecosystem services in Wangkuai Reservoir watershed was identified,the ecological security pattern of Wangkuai Reservoir watershed was constructed based on the minimum cumulative resistance model(MCR).The main contents and results are as follows:(1)The spatial and temporal characteristics of ecosystem services in Wangkuai Reservoir watershed showed that the average water conservation was 53.97 mm,the soil conservation was 144.37 t/hm2,and the carbon storage was 25.97 t/hm2 in the years from 2000 to 2020,the habitat quality was 0.79,n output was 0.59 kg/hm2,P output was 0.07 kg/hm2.The water conservation,soil conservation,carbon storage and habitat quality showed an upward trend,while N output and P output showed a downward trend during the past 20 years.Soil conservation,carbon storage and habitat quality were higher in the west than in the east,and N and P output were higher in the east than in the west.The results showed that carbon storage and water conservation were significant trade-offs,soil conservation,carbon storage and habitat quality were significant synergies N and P outputs were significantly synergistic with water conservation,and significantly trade-off with soil conservation,carbon storage and habitat quality.(2)The results of ecosystem service function analysis of different land use types showed that the grassland area decreased and the woodland area increased gradually in Wangkuai Reservoir watershed during the past 20 years,the increase of forestland area was mainly caused by grassland transfer.The water conservation capacity,habitat quality index,soil conservation capacity and carbon storage capacity of forest land were the largest,while the N and P output of water area were the largest.The correlation between land use change and ecosystem service function showed that grassland was positively correlated with N and P output,and negatively correlated with carbon storage and habitat quality Forest land was positively correlated with carbon storage and habitat quality,negatively correlated with N and P output,and cultivated land was positively correlated with N and P output.(3)The results of calculating the landscape pattern index of each sub-watershed show that:from 2000 to 2020,the degree of landscape fragmentation decreases,the shape of landscape becomes more complex,the connectivity of landscape becomes stable,and the heterogeneity of landscape types increases,the dominance degree of patch was reduced and the aggregation degree of each land use type was relatively stable.The results showed that soil conservation and habitat quality were negatively correlated with CONTAG,ED,IJI,LSI,NP,PD,SHDI,and positively correlated with AI.Carbon storage was negatively correlated with CONTAG,and N and P output were positively correlated with CONTAG and IJI.(4)The ecological security pattern,which is composed of ecological source area,ecological corridor and ecological node,is determined in this paper.The results show that the total area of ecological source area in Wangkuai reservoir watershes is 732.14 km2,which is mainly distributed in the southwest and northeast,there are 14 first-class corridors with a total length of 56.94 km and 28 second-class corridors with a total length of 329.31 km.They then compared the spatial distribution and size of the components of Fuping County’s urban-rural master plan(2013-2030)and the ecological security framework,it can provide scientific basis for the division and classification management of Wangkuai Reservoir watershed.