| LUCC(Land Use and Land Cover Change)will cause the change of the surface landscape structure,and the land use structure,land use mode and spatial pattern of land cover will have a certain impact on the ecosystem structure and ecological process,thereby affecting the ecosystem services.Therefore,it is of great significance to describe the temporal and spatial evolution of ecosystem services,analyze the trade-offs and synergies among services,and explore the relationship between LUCC and ecosystem services.Based on the land use data of 2000/2005/2010/2015/2018,this study evaluated four ecosystem services including water yield,carbon storage,soil conservation and habitat quality by analyzing the evolution process of land use/cover in the Dongting Lake region and combining InVEST model.The correlation coefficient method was used to calculate the trade-offs and synergies between the four services,and the impact of LUCC on ecosystem services in the region was discussed.The results show that:(1)The land use type of the Dongting Lake region changed from weak land use intensity in the west and southeast to strong land use intensity in the middle and north.The main land use types were cultivated land,forest land and water area.The change characteristics of land use area in the study area during 18 years were continuous increase of construction land,water area and unused land and continuous decrease of cultivated land and forest land.The area of cultivated land,forest land and grassland all decreased to different degrees,among which the change range of cultivated land was the largest,with a total decrease of 1419.04km2(change rate:-42.69%),forest land decreased by 5.55%,grassland decreased by 1.76%.The area of construction land,water area and unused land increased significantly,among which the construction land increased by 950.06km2(change rate:28.58%).The water area increased by 441.22km2(change rate:13.27%);The area of unused land increased from 1.44%to 1.88%.From 2000 to 2018,there were 30 types of land use transfer.The main types of land use transfer were cultivated land,water area and forest land,and the main types of land use transfer were water area and construction land,while some unused land expanded.Construction land and cultivated land fluctuated sharply,and the change of cultivated land transfer was the most significant,which mainly shifted to water area of 1210.93km2,accounting for 43.92%of the total transfer area of cultivated land.Construction land transfer accounted for 30.29%and forest land transfer accounted for 23.49%;549.81km2 of water area was transferred to cultivated land,accounting for 49.34%of the total area of water area transferred,and 234.16km2 of construction land was transferred to cultivated land,accounting for 79.74%.(2)The four ecosystem services in the Dongting Lake region showed a spatial distribution characteristic of high in southwest,northwest,southeast,northeast and low in central.During the study period,the four ecosystem services continued to decrease in the order of water yield>soil conservation>habitat quality>carbon storage.Among them,water yield decreased by 47.68×108m3.Carbon storage decreased by 1006.76×104t.Soil conservation decreased by 20.94×107t.The habitat quality decreased by 733.95×103/km2.(3)From the trade-offs between ecosystem services and cooperative relations,the Dongting Lake region of four types of ecosystem services on the interannual variation is given priority to with collaborative relationship,only water yield&habitat quality(WY&HQ)in 2010 as the weak correlation(r>0,p>0),the remaining four years shows a negative correlation between(r<0,p>0).It shows that there are trade-offs between them.In addition,the pairwise comparisons of the other five ecosystem services are all positively correlated with significance greater than 0.01,indicating that they are significantly synergistic,that is,the increase of one service will lead to the increase of another service.The synergistic relationship among services is as follows:CS&HQ>CS&SC>WY&CS>SC&HQ>WY&SC.The trade-offs and synergies among the four types of ecosystem services show obvious regional heterogeneity in space:there were extremely significant trade-offs between carbon storage and soil conservation as well as between carbon storage and habitat quality(R<0,0.01<P<0.05),extremely significant trade-offs between water yield and soil conservation as a whole,and extremely significant synergies(R>0,0.01<P<0.05)in some areas(south Dongting Lake).The synergistic relationship between water yield and carbon storage is very significant in the northeast region,and there is a very significant trade-offs relationship along the east and west south Dongting Lake.The order of coordination degree is WY&CS>SC&HQ>WY&HQ>WY&SC>CS&HQ>CS&SC.(4)There were differences in the ability of different land uses to provide various ecosystem services:except the water yield ability was in the order of cultivated land>forest land>construction land,the carbon storage and habitat quality ability of different land types was in the order of forest land>cultivated land>water area,and the soil conservation ability was in the order of forest land>cultivated land>grassland.Unused land and construction land provide the worst soil conservation and habitat quality services.Forest land and cultivated land are important land types that provide excellent ecosystem services in the Dongting Lake region.From 2000 to 2018,the trade-offs relationship between LUCC and four ecosystem services in the Dongting Lake region was the main one.The trade-offs relationship between LUCC and water yield was extremely significant(R<0,P<0.01).There was a significant trade-offs relationship between LUCC and carbon storage,with a very significant negative correlation(-0.117**)in 2018,a significant negative correlation(R<0,P<0.05)in 2005,2010 and 2015,and a negative correlation(R<0,P>0.1)in 2000.There was a trade-offs relationship between LUCC and habitat quality,and there was a significant negative correlation between LUCC and habitat quality in 2015(-0.107**).LUCC maintained a weak trade-offs relationship with soil conservation,which was positively correlated in 2000 and 2015(R>0,P>0.1),and negatively correlated in 2005,2010 and 2018(R<0,P>0.1).Therefore,forest land plays a very important role in carbon storage,soil conservation and habitat quality services in the Dongting Lake region.Cultivated land has made great contribution to water yield.The trade-offs relationship between LUCC and the four services shows that with the deepening of land use intensity and the transfer of cultivated land and forest land to construction land,the ecosystem service capacity in the region will inevitably decrease.The comprehensive assessment of LUCC and ecosystem services can not only achieve quantitative assessment of regional ecosystem services,but also show their trade-offs and synergies at the spatial scale.The results can provide scientific suggestions and countermeasures for realizing dynamic and stable development of regional LUCC and ecosystem services. |
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