| Promoting the healthy and sustainable development of landscape on a regional scale and ensure the supply capacity of ecosystem services is important.It is not only the guarantee of regional ecological security,but also the basis for maintaining the balance of natural ecosystems and the normal conduct of socio-economic activities.Dongting Lake,with its complex human-land coupling,is an ideal place to study land use change(LUCC),ecosystem processes and the spatio-temporal evolution of ecosystem services,which is helpful to solve key technical and scientific problems in the field of interdisciplinary ecosystem services research and promote the theory and practice of sustainable development in the area.Based on the annual land use data of Dongting Lake for 30 years(1988-2019),this study analyzes the spatial-temporal evolution characteristics of LUCC and landscape patterns from multiple spatial scales of global,district and pixel,respectively.Through the further analysis of the spatio-temporal dynamic change and synergy relationship of ecosystem services in Dongting Lake,as well as the exploration of LUCC on the influence mechanism of landscape pattern and ecosystem services,it provides a scientific basis for the formulation of eco-environmental management policies and land use strategic planning in the lake area.Therefore,this study is of great practical and strategic significance for promoting the ecological construction and protection of Dongting Lake and promoting the high-quality development of the ecological environment of the Yangtze River Economic Belt.The main research results of this study are as follows:(1)The optimized CCDC algorithm was used to quantitatively analyze the changes of different land use types and landscape patterns in Dongting Lake from 1988 to 2019.On the one hand,during the study period,all land use types in the Dongting Lake have experienced great interannual changes,in which forests and impervious surfaces have increased significantly,while bare land and farmland have declined significantly;At the same time,the changes of various land use types in Dongting Lake in the past 30 years have shown obvious spatial heterogeneity.On the other hand,the landscape types in Dongting Lake are diverse,and the degree of landscape fragmentation continues to increase.Each landscape type is greatly constrained by natural conditions,and patches tend to disperse;The fragmentation degree of cultivated land patches increased,and the spatial connectivity became weak,while the fragmentation degree of forest land showed a trend of"first decreasing and then increasing" with the aggregation increased;The fragmentation of construction land is also increasing,and urban construction is highly concentrated.(2)The temporal and spatial characteristics of ecosystem services such as carbon storage,GPP,water conservation and crop yield in Dongting Lake were analyzed,as well as the trade-offs and synergies between ecosystem services.The results show that the carbon storage,GPP,water conservation and crop yield in the Dongting Lake have increased.The risk of flood and waterlogging has decreased in the central region but increased in some surrounding regions.The spatial distribution pattern of ecosystem services did not change significantly on the time scale.The trade-offs and synergies(correlations)between different ecosystem services are quite different:there is a strong positive correlation between grain yield and carbon storage,GPP;The risk of flood and waterlogging is a tradeoff relationship with carbon storage and GPP;GPP and carbon storage are synergetic;Carbon storage and water conservation show weak synergy.In addition,there are also large spatial differences in the aggregation of hotspots of trade-offs and synergies among ecosystem services.(3)The extensive nonlinear relationship between landscape pattern and ecosystem services was revealed.Among them,carbon storage has a strong correlation with forest,farmland,water body,impervious surface and bare land area,while water conservation has a weak correlation with various land use types.The nonlinear relationship between landscape pattern indicators and ecosystem services changed significantly on an interannual scale.(4)Based on the Basis(BS),Economic Development(ED),Environmental Protection(EP)and Sustainable Development(SD)scenarios,PLUS model was used to simulate and predict the land use in Dongting Lake in 2035.The results showed that the land use change of various land types showed great differences under different development scenarios.Among all districts and counties in Dongting Lake,Yueyang County has the highest forest area,but its forest area is the lowest under the ED scenario,and its relative change is also low;Yuanjiang has the highest wetland area,while its wetland area is the lowest under the SD scenario,with a very high relative reduction;Changde has the largest cultivated land area,but its cultivated land area is the lowest under the BS scenario,and the relative reduction is extremely high;Yueyang County has the largest water area,but its water area is the lowest under the BS scenario,and its relative reduction is also the lowest;Changde has the largest impervious surface area,while its impervious surface area is the lowest in the SD scenario,and the relative reduction is at the middle level in all districts and counties.The study also found that the main driving factors of different land use types are different,and the elevation has a high contribution to most land type changes.This study systematically established a high spatial and temporal resolution Dongting Lake LUCC database(1988-2019),a multi-dimensional database of spatial and temporal evolution of landscape pattern and ecosystem services.Based on these databases,the temporal and spatial evolution laws and regulation mechanisms of LUCC,landscape pattern evolution,and ecosystem service process were analyzed in depth,and the nonlinear relationship between landscape pattern and ecosystem service and the landscape regulation mechanism of ecosystem service were quantitatively revealed.This study provides a scientific reference for land use planning,landscape pattern regulation policy,and ecological service management and optimization of Dongting Lake.In addition,it also provides comprehensive information support for the applicability management of major ecological issues on the regional scale and the protection and improvement of ecosystem service functions. |
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