| In the context of global warming and the intensification of human activities,various ecosystem services are constantly degrading.How to maximize the benefits of ecosystem services and the harmonious coexistence of man and nature by studying the balance of ecosystem services has become a global hot spot problem.The Heihe River originates from the northern foot of the Qilian Mountains and is the largest inland river outside the Tarim River Basin in the northwestern inland region.The upper reaches of the river basin provide a material basis for the ecological security and economic development of the Hexi Corridor,and the quality of its ecosystem services directly affects the ecological environment quality of the entire river basin.In recent years,the upstream ecological environment has been gradually deteriorating,posing a serious threat to the surrounding environment,the production and life of the cities in the middle and lower reaches,and ecological security.This study uses the water supply and soil conservation module of the InVEST model and the CASA model to calculate water supply services,vegetation carbon storage services and soil conservation services in the upper Heihe River basin in 2000,2005,2010,2015 and 2018..First,analyze the spatial and temporal changes of the three ecosystem services in the study area from 2000 to 2018 and the trade-off and synergy between the services.Secondly,on this basis,use the differentiation and factor detection in the geographic detector to explore the influence of geographic environmental factors on the trade-off and synergy of the three ecosystem services in the region.Finally,the regions are divided according to the main influencing factors,different land use scenarios are set up in different regions,and the three ecosystem service function changes under multiple scenarios are simulated,and the best land use plan is selected,with a view to the ecological environment in the upper reaches of the Heihe River.Construction and environmental planning provide a certain scientific reference basis.The main conclusions obtained are as follows:(1)The spatial distribution of the three services of water production,vegetation carbon sequestration and soil conservation in the upper reaches of the Heihe River decreases from the southeast to the northwest.According to the topographic map of the study area,it also shows a distribution pattern of high mountains and low valleys.From 2000 to 2018,the total amount of the three services has increased.The total water production has fluctuated from 14.65×108m3 in 2000 to 21.45×108m3 in 2018,and the total carbon sequestration of vegetation has increased from 6.75TgC to 9.08 year by year.TgC,the total amount of soil conservation increased from 1.86×108t in 2000 to 1.97×108t in 2018.Although the total amount has increased,there is a partial decrease.The increase and decrease of the three services between 2000 and 2018 is roughly as follows:the depth of water production increases in the south and decreases in the north,the carbon sequestration of vegetation increases in the east and the west decreases,and the soil conservation decreases in the east and west and increases in the middle.-The increase and decrease of the three services between 2018 is spatially heterogeneous.The degree of increase or decrease in service is:water production from-195.27mm to 302.23mm,vegetation carbon sequestration from-561.75gC·m-2 to 566.77gC·m-2,and soil conservation from-396.91t/ha to 403.29t/ha.(2)From 2000 to 2018,the three services were synergistic with each other on the basin scale,but the degree of synergy was low,and there were a lot of trade-offs in some areas.The main trade-off between water production and vegetation carbon sequestration in the upper reaches of the Heihe River is that water production decreases and vegetation carbon sequestration increases;the main trade-off type between vegetation carbon sequestration and soil conservation is soil conservation reduces vegetation carbon sequestration and increases;in the relationship between water production and soil conservation,production Water increases and soil conservation decreases the most types.(3)Among the three ecosystem services in the watershed,the relationship between them is that vegetation carbon sequestration acts on water production in one direction,and water production passively bears the impact of vegetation carbon sequestration;vegetation carbon sequestration acts on soil in a single direction.Conservation,soil conservation is passively affected by vegetation carbon sequestration;water production and soil conservation interact indirectly through vegetation carbon sequestration.Although the three ecosystem services are related to each other,due to directional problems,they cannot form a closed cycle and cannot be a virtuous cycle in a solid line area.Therefore,vegetation is the key to the restoration of the upper reaches of the Heihe River.(4)The main influencing factors of the synergy of regional ecosystem service trade-offs are changes in land use,elevation,slope and precipitation.The interaction of all factors is stronger than that of a single factor,and the land use factor has the strongest influence on the trade-off and synergy of the three services in the region.The decrease in precipitation and the growth of vegetation are the main reasons for the decrease in water production,and as the elevation and slope increase,the degree of trade-off becomes more prominent.(5)The four scenarios of natural development priority,economic development priority,ecological protection priority and water resource supply priority are set in zoning.In the optimal land use optimization plan selected through simulation,the coverage of forest land and grassland coverage are improved,And from the perspective of local trade-offs in space and overall synergy in time,the degree of trade-off decreases and the degree of coordination increases.The optimized plan provides a scientific basis for the coordinated development of regional economic ecology. |
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