Study On Spatial-temporal Change And Trade-off Relationships Of Ecosystem Services In The Hanjiang River Basin Based On GIS

Ecosystem services are all the benefits that humans derive from ecosystems.It has the spatial distribution heterogeneity,complexity and diversity of human management and utilization methods.In recent years,with the continuous population growth and the rapid development of the social economy,the ecosystem has been seriously damaged and the ecosystem service capacity has been affected.Therefore,the ecosystem function has been weakened or even degraded.People are gradually realizing that human activities and government policies have changed the land use pattern and the spatial distribution of resources.These changes have changed the ability of ecosystem products and services to be provided through the impact on ecosystem patterns and processes.Therefore,research on the trade-offs and synergies between ecosystem services will help to improve the overall efficiency of ecosystem services and ensure the sustainable supply of ecosystem services,which is of great significance for economic development and ecological environment protection.In this paper,the Hanjiang River Basin is used as the study area,and the value of ecosystem services in the six periods from 1990 to 2017 is estimated.And the characteristics of temporal and spatial dynamics are analyzed.The trade-offs and synergies among ecosystem services were analyzed via correlation analysis from three aspects: the whole basin,the areas upstream and downstream of the dam taken separately,and the combination of the areas upstream and the downstream of the dam.Finally,ecosystem service hotspots are identified.The research content of this paper mainly includes:(1)Estimation the ecosystem services value.The CASA model was used tocalculate the carbon storage and oxygen release value.The Statistical Yearbooks and land use data were used to calculate the food production value.The water balance method and the alternative cost method were used to calculate the water supply value.The soil loss equation was used to calculate the value of soil and water conservation value.Calculate the cultural tourism value.(2)Using the ecosystem service change index to analyze the temporal and spatial changes of ecosystem services and study its loss-gain situation.(3)Analyze the changes of the ecosystem service trade-offs and synergy relationship.On the basis of calculating the different ecosystem services value,the trade-offs and synergies among ecosystem services were analyzed via correlation analysis from different aspects and different periods in the Hanjiang River Basin.(4)Identify the distribution of multiple service hotspots in the Hanjiang River Basin through hotspot identification,and comprehensively understand the impact of the relationship between ecosystem services and services.Through the research,the following conclusions are obtained:(1)From 1990 to 2017,the carbon storage and release of oxygen value in the Hanjiang River Basin showed a trend of decreasing fluctuation.In space,carbon storage and oxygen release value in the past years showed a low spatial pattern in the northeast and southwest.The food supply value shows a fluctuating trend,food supply value downstream is higher than upstream.Water conservation value showed a trend of decreasing fluctuation.From 2000 to 2010,water conservation value has increased.The spatial pattern of water conservation value has changed greatly over the years,but water conservation value in the southwest has always remained at a high value.The overall soil conservation value showed a volatility growth trend,and in the space,soil conservation value is mainly high in the southwest and the east is low.The cultural tourism value is increasing year by year.The cultural tourism value in the upper stream is higher than the downstream,which is about 1.5?3.5 times of the downstream.(2)Through the correlation analysis among the five kinds of ecosystem services such as carbon storage and oxygen release,food supply,water conservation,soil and water conservation and cultural tourism from 1990 to 2017,it can be seenthat the synergy relationship between ecosystem services in the Hanjiang River Basin accounts for 52%,mainly in the carbon storage and oxygen release and other types of ecosystem services.The trade-offs relationship accounts for 48%,mainly in food supply and other types of ecosystem services.In 1995-2017,the relationship of ecosystem service in the Hanjiang River Basin showed a fluctuating trend.Among them,40% of the synergy relationship showed an increasing trend,and 60% showed a decreasing trend.In the trade-offs relationship,40% of the trade-off relationship is increasing,and 60% is decreasing.The proportion of synergy in the upstream of the Hanjiang River Basin is greater than the downstream.The relationship between the two groups of ecosystem services differs between upstream and downstream.The relationship between some ecosystem services is synergy in the upstream,however,this relationship may change to trade-offs in the downstream.The ecosystem service synergy between the upstream and downstream of the Hanjiang River Basin accounted for 52%,and the trade-off relationship accounted for 48%.The trade-off relationship mainly existed between water conservation and other types of ecosystem services,accounting for 54.54%.From 1990 to 2017,the high-value hotspots of ecosystem services in the Hanjiang River Basin were distributed in the southwestern part of the basin.The mid-high-value hotspots were distributed in the southern part of the basin,and the median and low-value areas were distributed in the basin.The median area is the dominant area of the upstream and downstream,accounting for77.52% and 75.99% respectively.