Ecosystem Service Tradeoff And Synergistic Relationship Under Land Use/Land Cover Change In Erhai Basin

Land use/land cover change is an important driving factor affecting ecosystem services.The change of land use pattern and intensity often has an important impact on the supply capacity of ecosystem services and the balance between services.The current ecological research focus is to evaluate the spatial-temporal pattern of ecosystem services,analyze the impact of land use/land cover change on ecosystem services,and quantify the trade-offs and synergies among services,which are the fundamental needs of ecological sustainable development.It is of great significance to analyze the impact of future land use/land cover change on ecosystem services and the trade-offs and synergies of various ecosystem services based on land use scenarios for maintaining regional ecological security and improving ecosystem services.This study takes Erhai Basin as the research object.Based on PLUS model,natural growth scenario,ecological protection scenario and economic growth scenario are set to simulate land use/land cover type map in 2030.Using the method of land use change rate and transfer matrix,the characteristics of land use/land cover change under different scenarios in 1990/2000/2010/2020 and 2030 in the study area were analyzed.The temporal and spatial characteristics of seven ecosystem services(carbon storage,crop yield,recreation potential,habitat quality,soil conservation,water conservation and nitrogen output)were evaluated by the In VEST model and ROS model,and the effects of land use/land cover change on ecosystem services were statistically analyzed by GIS software from 1990 to 2030.SPSS and bivariate local Moreland index identify trade-offs and synergies among ecosystem services.The results show that:(1)During 1990 to 2020,the pattern of land use/land cover type in Erhai Lake basin changed to some extent.Woodland is the main land type in Erhai Lake basin,accounting for more than 43% of the total land types,but the growth rate of woodland area decreased year by year.Construction land accounts for less than 1% of the total area,but its expansion rate is the fastest.The grassland area continued to decline,and the cultivated land area showed a trend of decreasing first and then increasing.Grassland was mainly converted into woodland,cultivated land and shrub,and the conversion area was 154.03km2,60.22 km2 and 12.24 km2,respectively.The cultivated land was mainly converted into grassland,forest land and construction land,and the conversion area was 126.21 km2,78.45 km2 and 11.64 km2,respectively.The natural growth scenario follows the law of land use/land cover change from 1990 to 2020.Woodland,shrub and grassland are effectively protected under ecological protection scenario,while cultivated land and construction land continue to expand under economic growth scenario.(2)The spatial patterns of carbon storage,habitat quality,soil conservation,and water conservation in ecosystem services were similar,with the variation characteristics of high in the surrounding area and low in the central area.The spatial characteristics of recreation potential were high in the central and western areas,and low in the central cultivated land area.The spatial characteristics of crop yield and nitrogen output were high in the central area and low in the central area.Carbon storage(81.3 t/ha),recreation potential(1.431),habitat quality(0.793)and soil conservation(765.62 t/ha)were all increased in ecological protection scenarios.Water conservation(61.23 mm)reached the maximum supply capacity in the natural growth scenario.In the economic growth scenario,crop yield(89,304.11 t)and nitrogen output(1.98 t/ha)increased,while the development of other ecosystem services was restricted.The increase of woodland,shrub land and grassland area had positive effects on carbon storage,recreation potential,habitat quality,soil conservation and water conservation,while the increase of cultivated land area had positive effects on crop yield and nitrogen output.(3)In different scenarios from 1990 to 2020 and 2030,crop yield-nitrogen output in Erhai Basin showed a synergistic relationship,and both showed significant tradeoff relationship with other ecosystem services.In addition to nitrogen output,crop yield and other ecosystem services presented tradeoff relations in the surrounding woodland area of Erhai basin,and in the central cultivated land area also presented tradeoff relations with most ecosystem services.Most ecosystem services in the surrounding woodland area showed a synergistic relationship,indicating that woodland is an important land use/land cover type to ensure ecosystem service supply capacity.