| Ecosystem services are the key basis for human survival and development,so clarifying the process of ecosystem service supply,delivery and consumption is an important prerequisite for ecosystem management decisions.Processes of ecosystem service supply-pass-consumption has significant spatial and temporal variability and complexity.Understanding the relationship between ecosystem services and livelihoods in a changing environment can help reveal the supply-pass-consumption mechanism of ecosystem services,is a key part of the Nature based Solutions.The Three Gorges Reservoir area(TGRA)is an important ecological fragile area and an important ecological function area in China,where the contradiction between ecological protection and rural economic development is prominent.For a long time,the implementation of the high-intensity forest restoration project in the TGRA has influenced the structure and function of the ecosystem,and then affected and changed the process of ecosystem service supply-pass-consumption and the interests of different interest groups,but the temporal and spatial variability and complexity of the impact are still unclear.This study aims to study the temporal and spatial characteristics of ecosystem service supply and demand and its correlation with the livelihoods of farmers in the TGRA under the background of forest restoration,to reveal the relationship between ecosystem services and farmers’ livelihood in mountainous reservoir area and support regional sustainable development decisions.In this study,20 counties in the TGRA were selected as the research objects to study the characteristics of spatial and temporal changes in land use/ cover patterns from 2000 to 2020;the supply and demand characteristics of key ecosystem services such as food supply,water supply,water purification,carbon sequestration,and soil conservation in the TGRA were quantitatively assessed using In VEST,CASA,and RUSLE models;the supply-demand matching characteristics of ecosystem services at the county scales and divide the supply-demand matching patterns were characterized by the supply-demand ratio and K-means clustering method.On this basis,the livelihood level of farmers were assessed by a sustainable livelihood framework to reveal the correlation between the supply and demand of ecosystem services and the livelihood of farmers.The main research results are as follows:(1)The spatial and temporal evolution of land use/cover types in the TGRA was dramatic from 2000 to 2020.The area of forest land and farmland was relatively large,with forest land mainly distributed in the northeastern and southwestern mountainous regions and farmland mainly distributed in the central and western plain hilly regions.Under the ecological restoration project,a large amount of farmland was converted to forest land,with the largest increase in shrub forest area,followed by coniferous and mixed forests.The woodland area in all counties showed an increasing trend,with a larger increase in the central part of the reservoir area,a higher rate of change in the western part,and a smaller increase and rate of change in the northeastern and southern mountainous areas.Among the non-vegetation types,the area of construction land was the largest and had a significant growth trend,mainly concentrated along the Yangtze River,especially in the core urban area of Chongqing in the west.(2)There was a significant difference in the spatial and temporal variation of ecosystem service supply.Food supply and water supply were both spatially distributed in a "low in the east and high in the west" pattern and were higher in the central part of the reservoir area,while food supply was decreasing and water supply was decreasing in the northeast and south of the reservoir and increasing in the central and west.The supply service was significantly positively correlated with the proportion of agricultural land and negatively correlated with the proportion of forest land.Water quality purification,carbon sequestration,and soil conservation all showed the distribution characteristics of "high in the east and low in the west",and increased over time,with higher growth rates in the central and western parts of the reservoir area,with low values of water quality purification concentrated in the central part of the reservoir area,and low values of carbon sequestration and soil conservation concentrated in the western part of the reservoir area.The regulating services were significantly and positively correlated with the proportion of forest area,in addition to the slope and elevation.(3)The demand of ecosystem services showed unevenness in spatial and temporal changes.The demand for food supply,water supply,and carbon sequestration services all showed the spatial distribution characteristics of "low in the east and high in the west",with the demand for food supply services increased in the western part of the reservoir and decreased in the eastern part,while the demand for water supply and carbon sequestration services showed an increasing trend with a higher growth rate in the western part of the reservoir.The demand for soil conservation services showed the spatial distribution characteristics of "high in the east and low in the west",showed a decreasing trend and a higher rate of decrease in the northeast and south of the reservoir area.The demand for food supply,water supply and carbon sequestration services was significantly and positively correlated with the population and construction land area ratio,while the demand for soil conservation services was significantly and positively correlated with the slope and elevation.The demand for water quality purification service showed the distribution characteristics of "high in the middle and low at the two ends",which was slowly decreasing and the rate of decrease was higher in the central and western parts of the reservoir area,and the demand for water quality purification service was significantly and positively correlated with the number of rural population and the proportion of farming land.(4)Food supply,water supply,carbon sequestration,and soil conservation services all showed supply surpluses,while water quality purification services showed supply deficits in 2000 and 2010,and there were spatial mismatches in all services except soil conservation.Forest regulation supply model had the highest supply level of regulating services,the lowest supply level of supply services,and low demand level of each service,with an overall supply surplus state.Agroforestry composite business model had a medium level of supply and demand for each service,and the service supply can meet the demand.Ecological agriculture supply model had the highest supply level of supply services,the highest demand for water quality purification,and a serious deficit in the supply of water quality purification services.Urban development demand model had low supply and high demand of each service,and the overall supply deficit state.(5)The livelihoods of farmers in the TGRA were increasing,and the growth of financial capital was the key to the increase of livelihoods,while the change of ecosystem services under forest restoration had a relatively small impact on the livelihoods of farmers.The distribution of farmers’ livelihoods in the reservoir area was characterized by a "high in the west and low in the east",with larger increased in the core city and surrounding counties of Chongqing in the west,and with smaller increased in the northeastern and southern mountain counties,but the degree of change was most obvious.Farmers’ livelihoods were positively correlated with the supply and demand levels of supply services,and negatively correlated with the supply and demand levels of regulating services,but the correlation coefficients with both supply and regulating services were small.Among the four types of service supply and demand patterns,the larger ratio of supply to demand for ecosystem services,the lower level of farmers’ livelihoods.(6)The supply and demand levels of ecosystem services changed under forest restoration,and there was a serious mismatch between supply and demand,and a spatial separation between farmers’ livelihoods and ecosystem services.Ecological protection and ecological compensation under zoning control are important strategies to balance the supply and demand levels of ecosystem services and enhance farmers’ livelihoods. |
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