Trade-Offs And Synergies Of Ecosystem Services In Nanliu River Basin Based On InVest Model

Nanliu River is the first river in Guangxi to reach the sea.With abundant water resources,it plays an important role in the development of agricultural economy on both sides of the river.With the development of Beibu Gulf Economic Zone,the ecological environment and social economy of Nanliu River Basin are facing severe tests.It is of great significance to explore the changes of ecosystem services in the basin under the combined action of human and natural factors,and to analyze the trade-offs and synergistic relations of ecosystem services,so as to formulate appropriate "win-win" policies to coordinate the economic development and ecological protection in the Nanliu River Basin.This study is based on TM data,soil data,meteorological data,DEM data,MOD13Q1 remote sensing data,Guangxi Statistical Yearbook and other data,combined with domestic and foreign researches on ecosystem services and research results of ecosystem services in Nanliu River Basin.Carbon stock,water conservation,soil conservation,habitat quality and net primary productivity(NPP)are estimated by using Arc GIS and InVEST models in2000,2006,2010 and 2015.Combined with radar maps,the spatial and temporal distribution patterns and differences of ecosystem services at different spatial scales(whole region,subwatershed,slope grade and different landuse)were analyzed,and the cold and hot spots of different types of ecosystem services were identified by spatial superposition.The correlation coefficients of ecosystem service pairs at different spatial scales were calculated by using SPSS software,and the trade-offs and synergies among ecosystem services were explored.K-means clustering analysis was written in Python language,and the watershed ecological functional areas were divided by combining ecosystem service clusters and landuse types.Rational management were put forward according to the differences of ecological and economic conditions in different regions.Through the analysis,the main conclusions are as follows:(1)From 2000 to 2015,carbon stock services,water conservation services and habitat quality services showed an increasing trend,while soil conservation services first decreased and then increased,while NPP services showed a decreasing trend.Ecosystem services of each subwatershed showed obvious differences.On the slope level,carbon stock,water conservation,soil conservation and NPP per unit area increased with the increase of the slope,while the total amount generally showed a wavy distribution,while the habitat quality decreased with the increase of the slope.From the perspective of landuse,the ecosystem services of woodland,grassland,garden and cultivated land are stronger.(2)Based on the overlaying analysis of the assessment results of ecosystem service types,five types of hot spots were obtained.One type of hot spots mainly provided water conservation and habitat quality services.The second type of hot spots mainly provide habitat quality services,water conservation,NPP,water conservation and carbon stock services.The third type of hot spots mainly provide carbon stock services,water conservation,soil conservation,NPP services and habitat quality services.The fourth type of hot spots mainly provide services of carbon stock,water conservation,soil conservation,NPP and habitat quality.The fifth types of hot spots have less area and provide higher value services for the ecology(3)The correlation coefficients of ecosystem service pairs in Niliujiang River Basin were calculated by SPSS software,and the trade-offs and synergies between ecosystem service pairs had a certain scale effect.Therefore,the trade-offs and synergies among the whole region,subwatershed,slope grade and landuse type were explored under four spatial scales.At four spatial scales,water conservation-NPP,water conservation-habitat quality,water conservation-carbon stock,and water conservation-soil conservation are trade-offs,while other service pairs are synergistic.There were significant differences in the correlation between the service pairs in subwatershed scale,slope grade and landuse type.(4)Based on the ecosystem services of K-means cluster analysis results,combined with Nanliu River Basin landuse,divided into 5 ecological functional area:water conservation ecological function areas,forestry soil and water ecological protection functional area,agricultural production ecological function area,agricultural and forestry production ecological function area,ecological functional zones will be developed in urban areas.