| Ecosystems play an important role in people’s daily lives,providing a variety of ecosystem services to meet human needs to varying degrees,specifically in three situations: supply exceeds demand,supply exceeds demand,and supply and demand are in balance.Ecosystem services are also inextricably linked to each other in a synergistic relationship of mutual gains and trade-offs.Identifying and analyzing the spatial and temporal changes in the supply and demand of ecosystem services and the trade-offs and synergistic relationships are important for alleviating the regional ecological crisis brought about by rapid urbanization,promoting the effective protection of regional ecological space,enhancing the well-being of residents,and guiding the scientific management and protection of regional ecosystems.Taking Yiyang County as an example,this study uses 30 m annual land cover classification product CLCD(1980-2020)land use data from Wuhan University,and 362 administrative districts(353 administrative villages and 9 forest farms)in the study area as evaluation units(under 12 towns and 4 townships),combining soil data,NDVI data,rainfall data,NPP data,population data and statistical yearbooks Using the ecosystem service value assessment model,InVEST model and ArcGIS 10.2 software,we quantitatively assessed the spatial and temporal characteristics of the supply and demand values of four ecosystem services in Yiyang County,including water production service,carbon sequestration service,food production service and soil conservation service,as well as the trade-off/synergy relationship,using the modified equivalent factor method,shadow engineering method,market price method and spatial superposition method.Based on the assessment results,Yiyang County was divided into three spatial management zones,namely,the North-South Hill Zone,the Luohe River Zone and the Southwest Mountain Zone,and relevant recommendations and measures were proposed.The main conclusions are as follows:(1)Spatial and temporal changes in ecosystem service supply.(1)Spatial changes:from 2005 to 2020,the supply of water production services was low in the north and southeast,and high near the central river area and the southwest;carbon sequestration services showed that the value of carbon sequestration services per unit area north of the river was lower than that in the south;food production services showed that the value of food production services per unit area in the north was higher than that in other areas,and that the value of food production services per unit area near both sides of the river and in the southwest was low,especially in the southwest.Soil conservation service shows that the value of food production service per unit area in the southwest is higher than that in other areas,while the value of food production service per unit area in the north and southeast of the study area is lower than that in other areas,and more significant in the north.(2)Changes in quantity and time sequence: the total value of water production service supply first decreases and then increases,and the value per unit area increases year by year;the total value of carbon sequestration service and food production service supply and the value per unit area increase year by year;the total value of soil conservation service supply and the value per unit area increase and then decrease and then increase.(2)Spatial and temporal changes in the demand for ecosystem services.(1)Spatial changes: From 2005 to 2020,the areas with higher demand for water production,carbon sequestration,and food production services per unit area were mainly located in the eastern part of the study area and near the rivers,while the areas with lower demand per unit area were mainly located in mountainous areas and sparsely populated areas with large topographic relief;the demand for soil conservation services was divided by rivers,with the areas south of the rivers having a higher demand for soil conservation services and the rest having a staggered distribution.Soil conservation service demand is higher,the rest of the region soil conservation service demand high and low staggered distribution.(2)Quantitative time series changes: from 2005 to 2020,the total value of demand for water production services,carbon sequestration services,and food production services and the value of demand per unit area are increasing year by year;the total value of demand for soil conservation services and the value of demand per unit area first rise,then fall,and then rise.(3)Spatial and temporal changes in the matching of supply and demand of ecosystem services.(1)Water-producing services: 2005-2020 shows an overall phenomenon of low in the middle and high in the north and south.The supply-demand ratio in the areas near rivers is low,mostly in a state of supply exceeding demand;the southern and northern parts of the study area are mostly in a state of surplus supply exceeding demand;the supply-demand ratio for water production services is highest in some areas in the southwest.(2)Carbon sequestration services: from 2005 to 2020,most regions are in a situation where supply exceeds demand,and roughly one-sixth of the regions are in a state of surplus supply and demand,mainly in the downstream regions of rivers;some regions in the southwest have the highest ratio of supply to demand.(3)Food production services: 2005-2020 shows an overall state of low in the middle and high on both sides,with the south and north being higher than the areas near rivers;except for some areas where supply and demand are out of balance,other areas are basically in a balanced state of supply and demand.(4)Soil conservation services: the areas with higher supply/demand ratio of soil conservation services in2005-2020 are mostly distributed in the southwestern part of the study area;the supply exceeds demand in individual areas is more obvious,and the overall is at a balanced level.(4)Changes in ecosystem service trade-off/synergistic relationships.Overall,in 2005,the area of strong trade-offs was the largest(62.18%)and the area of high synergistic relationships was the smallest(10.51%),the overall ecosystem service benefits in the study area were not high and the coordination between various services needed to be improved.2010,the area of strong trade-offs was the largest(60.18%)and decreased compared to 2005,the area of low synergistic and weak trade-offs The proportion of the area of strong trade-offs remained stable(14.55%,13.19%),the proportion of the area of high synergistic relationships was 11.99%,and the overall ecosystem benefits improved,while the capacity of water production services and soil conservation services in strong trade-offs needed to be optimized and improved.2015,the proportion of the area of strong trade-offs remained the largest(59.49%),the proportion of the area of high synergistic relationships was the lowest(In 2020,the proportion of strong trade-offs tends to stabilize,the proportion of weak trade-offs and low synergies decreases,and the proportion of high synergies increases.The overall service efficiency of the ecosystem will be improved,and the coordination between various services will be improved.(5)Spatial management zoning.Starting from the matching results of ecosystem service supply and demand and the type of trade-off/synergy from 2005-2020,the study area was divided into the North-South hilly area,the Luohe River area and the Southwest mountainous area by combining its geographical characteristics,and different enhancement paths were given to each of the three areas according to their characteristics. |
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