Temporal-spatial Assessment Of Forest Ecosystem Services Under Different Land Use Scenarios In Gannan

With the acceleration of global population growth,industrialization and urbanization,land use change driven by human activities are exerting a severe influence on ecosystem services.The global ecosystems are now facing enormous strike.How to maintain its sustainability and how to deal with the tradeoff of multiple ecosystem services are challenging the whole human society.To formulate reasonable land management policy and enhance the ecosystem services,the mechanism of land use change need to be first explicated.The variation trend of land use should then be simulated based on this mechanism and the ecosystem services’ responses to different land use policies should be discussed.Gannan forest is an important safety barrier in southeast China.In recent years,Ecological engineering such as Natural Forest Protection,Close Hillsides for Forestry and so on have been implemented in this area.But its ecosystem service value is in a decrease.The analysis on the dynamic trend of ecosystem service values(ESVs)and its formation mechanism is of big practical and theoretical significance.In our study,land use change is considered as entry point,while land use remote sensing data and spatial statistic data are used as our database.The temporal-spatial dynamic evolution rules of Gannan forest ecosystem service value under different land utilization circumstances are studied based on the driving force analysis of its land use change.Strategies to promote the ecosystem service are then put forward.First,Land Use Dynamic Degree and Markov Transfer Matrix are adopted to analyze the dynamic variation of forest land structure and spatial distribution.Then spatial Logistic Regression is adopted to distinguish the driving factors of forest land cover change.Then incorporating CA,Logistic-CA-Markov complex model is constucted to predict the space-time evolution trend of forest land use under different circumstance.Based on the prediction,ESVs are evaluated using assessment approaches like market value method,shadow project approach and production cost method.Spatial statistics approaches such as Global Moran’s,Getis-Ord Gi* and spatial dependence matrix are applied to analyze their spatial coherence and aggregation of ESVs and their variation,as well as the synergy and tradeoff of different services.Finally,land use optimizing strategies are put forward based on the previous analysis and landscape pattern optimizing method.The main research work and results are as follows.(1)First are variation characteristics of forest land.The forest land is subdivided into colsed forest land,shrubbery,open forest land and other forest land.Their evolution patterns are analyzed through the difference in time domain and space.The causes of forest lands’ change are qualitatively discussed based on forest transition rules.It is found that the forest land use change in Gannan is becoming more obvious from the year 1990 to 2010.The dynamic degree of other forest land is relatively higher all through this period and its fluctuation is violent.The total area of forest lands has a little decrease,while the the structural change is obvious.The spatial distributions of 4 forest land types’ changes are of big difference.In the period of 2000-2010,forest land use change can mainly be divided in to two types.One is the internal transformation and another is mutual transformation between forest land and farmland.The transform from open forest land and shrubbery to closed forest land is the most outstanding one.The change of forest land into farmland is more than the change in the reverse direction,which is the main reason of the reduction of forest land area.What’s more,the change of forest in Gannan is not the same as in China,but conforms to its social and economic circumstances.(2)The second work is driving force analysis of forest land change.A driving factor set containing social,economic,location and environment variables is constructed base on the forest land cover change analysis and the objective reality of Gannan.The driving force analysis is implemented using spatial method in order to get overall grasp of the driving mechanism.It is found that the key driving forces for forest land use change are human activities and society and economy.Location and environment variables are secondary caused.For the change of closed forest land,shrubbery and other forest land GDP and population are key explaining variables.The higher is the GDP,the higher probability the three land types happen.This phenomenon reflects the acceleration of economy rise to forest land expansion and also verifies “forest land shortage path” theory.The bigger the population is,the smaller the growth probability of this 3 forest lands will be.This means the farmland and construction land are eroding the forest land in unavoidable way under urbanization background.For open forest land,the key driving force of its change is gradients.Bigger gradient means lower growth probability.In all,on one hand,the natural forest and planted forest of high canopy density is in a recovery increase,which shows that policies and regulation to protect forest resource has achieved initial success.On the other hand,with the development of urbanization and economic construction,the social and economic factors are posing greater influence to forest.Structural adjustment of agriculture mobilized by forestry and fruit growing leads to rapid expansion of economic forest.(3)The third is the evolution trend analysis under different land use scenarios.According to the development status and existing issues,4 land use scenes are set: current mode,planning mode,protecting mode and broad-leafization alteration mode.The land use prediction of 2020 is conducted based on transfer matrix and driving analysis.The influence of environment strategies on land cover change is discussed.It is found that the total area of forest land will decrease except in protecting mode.The structure and spatial pattern of forest land will change a lot in all circumstances.The area of closed forest land and other forest land will increase.The area of open forest land and shrubbery will decrease.The increase or decrease amplitudes in 4 scenes are quite different.Especially in the broad-leafization alteration mode,the closed forest land is rising obviously.The main transforms are mainly from open forest land to closed forest land,closed forest land to other forest land,shrubbery to closed forest land.The transform to closed forest land is distributed dispersively,while to other forest land gathers in Anyuan County and its circum.(4)The forth is the dynamic evaluation of multiple ecosystem service values and their temporal-spatial evolution characteristics.Accounting for ecosystem services in different stages and scenes is conducted and their change rule in time domain and space are analyzed.Thus how the ecosystem services response to the land use policy is discussed.It is found that the total ecosystem service value will continuously decrease without effective land use measures.The spatial autocorrelation of the value is growing with time.The high value sector is in the south of northeast southwest diagonal of Gannan.The change of the value also has spatial autocorrelation and spatial aggregation effect.Gannan’s main ecosystem services are atmosphere environmental purification,water conversation and Carbon sequestration.There are synergy and tradeoff of different extent between different services.Land use policies have remarkable influences to ecosystem services values.(5)Finally,strategies to enhance ecosystem service functions are put forward.The time and space analyzing framework constructed in this paper concludes society-economy-environment system,land use system and ecosystem.This framework enhances our understanding for the complex relationship between land use and ecosystem service function.Based on this framework and landscape pattern optimization theory,strategies and spatial optimization for land use is given,which are: broad-leafization alteration for pinus massoniana,specification for special economic forest,optimization for landscape pattern and establishment of dynamic mechanism for forest ecological compensation...