Landscape Pattern Optimization And Its Ecosystem Service Function Response In Karst Basins Based On Ecological Security

Under the national strategic background of ecological civilization construction,ecological security has an important position and significance in national security.Guizhou Province is a pilot area for ecological civilization in China and one of the most typical regions in the world where karst landforms are developed.Its ecological environment is relatively fragile,so it is necessary to explore scientific and effective ecological restoration paths in karst areas.Taking the Yeji River basin with widely developed karst landforms as an example,based on hydrological data and land use data from 2005 and 2020 in the study area,this paper first analyzes the spatiotemporal evolution characteristics and current ecological sensitivity characteristics of the landscape pattern in the study area;Secondly,based on the analysis results and the theory of landscape ecology,using methods such as MSPA model,landscape connectivity index analysis,MCR model,and circuit theory,identify ecological sources,extract ecological corridors,and ecological nodes to construct the ecological security pattern of the study area,and optimize the landscape pattern of the study area;Finally,SWAT model and In VEST model were used to analyze typical ecosystem service functions such as carbon fixation function,water conservation function,and soil conservation function after optimizing the landscape pattern in the study area.The main results are as follows:(1)The landscape type of the study area is mainly cultivated land landscape,followed by forest landscape.From 2005 to 2020,the main change pattern of landscape types in the study area is the transfer of cultivated land and grassland to construction land;The spatial distribution characteristics of the landscape pattern are as follows:at the overall level of the landscape,the fragmentation degree of the landscape increases,and the landscape diversity basically remains stable.However,both the spatial distribution of the landscape diversity and the fragmentation degree in the east side of the study area have significantly increased;(2)The ecological sensitivity distribution in the study area is mainly light to moderate,with light to moderate sensitivity areas accounting for 62.48%of the total area of the study area,mainly distributed in the north of the study area.Highly sensitive areas and non sensitive areas take the second place,with extremely sensitive areas accounting for the smallest proportion,mainly distributed in the south of the study area;(3)The proportion of suitable expansion areas for ecological sources in the study area is 91.6%,and the proportion of suitable expansion areas for urban sources is 8.4%.The area of suitable expansion areas for urban sources is far smaller than that of ecological sources.34 ecological source patches were identified,with a total area of 14906 hm~2,accounting for 13.58%of the total area of the study area,and distributed in a north-south direction.A total of 104ecological corridors have been extracted,with a total length of 444.85km(Figure 9a),including 87 low-cost paths,350.06km,and 17 potential paths,94.79km.A total of119 ecological nodes were identified,including 40 ecological pinch points and 79ecological obstacle points;(4)After optimizing the landscape pattern,the total carbon storage increased by 20.477kg,the total water production decreased by 17.56mm,and the total sediment production decreased by 73.35t/ha.The corresponding ecosystem service functions such as carbon storage,water conservation,and soil conservation were significantly improved.Therefore,landscape pattern optimization based on ecological security can effectively improve the habitat quality of the region and reduce soil erosion.The research results can provide new ideas for the restoration and reconstruction of ecological security in karst areas.