Ecological Security Pattern Construction Based On Multi-scenario Trade-off Of Ecosystem Services

The coastal zone,as a transition zone where land and sea meet,is a buffer zone for global environmental change,and it is also the region with the most frequent human activities.The mountains,rivers,forests,land,lake and grass form a community of shared life.As an important unit of it,the coastal zone provides various ecosystem services and plays an irreplaceable role in climate adjustments,water yield and biodiversity maintenance.However,with intensifying intensive and irrational development and application of coastal zones,many ecological degradation problems emerged,including sharp decline in biodiversity and wetland.In recent years,this threat has been exacerbated because cities along the coast have carried out a lot of land-reclamation activities,leading to over-exploitation and utilization of coastal resources,wanton occupation of coastal wetlands,and blind expansion of marine aquaculture.In this context,implementing national territory spatial restoration,speeding up the construction of national territory spatial security pattern and improving national territory's ecological carrying capacity have become important ways to ease the conflicts between ecological protection and land development.As ecosystem services are the natural environment and utility that humans depend on,scientific assessment of their spatial and temporal patterns as well as interaction mechanisms is of great significance in determining the basis of regional ecological environment,and then in building a regional ecological security pattern.Based on this,selecting Wafangdian,Liaoning province as research target,with the support of GIS,In VEST,CASA and other models,this paper will assess four typical ecosystem services including food supply,NPP,water yield and soil conservation in 2000,2007 and 2014.On the basis of this assessment and with the goal of weighing the competition among regional ecosystem services,OWA-GIS coupling model is introduced to identify the priority protection area for ecosystem services and minimum cumulative resistance(MCR)model is used to establish land-marine coordination and comprehensive ecological security pattern.The main research findings are as follows:(1)Spatial-temporal changes in ecosystem services.From 2000-2014,four ecosystem services all show inverted “U” trends(increase first from 2000 to 2007 and then decrease from 2007 to 2014)with different levels of fluctuation.Water yield processes the biggest fluctuation,with 69.43% increase from 2000 to 2007 and 49.40% decrease from 2007 to 2014.From the spatial perspective,in supply services(food supply and water yield),the fluctuation in western regions is higher than eastern,coastal than inland,plain than mountain.However,the support service(NPP)and adjustment service(soil conservation)have a distribution pattern that is completely opposite to the supply services.(2)Trade-off analysis of ecosystem services.In each year,except for NPP-soil conservation and food supply-water yield,which have synergistic relationships,other ecosystem services relationships have different strength trade-off effects.Two synergistic ecosystem services have totally different trends in this 14-year period.The synergistic level in NPP-soil conservation increase first(from 2000 to 2007)and then decrease(from 2007 to 2014),while that of food supply-water yield is opposite.There are same changes in trade-off ecosystem service pairs,the level of trade off in NPP-water yield and soil-water yield increase first and then decrease,and that of food supply-soil conservation is opposite.(3)Selection of the priority protection area for ecosystem services.Based on the OWA-GIS coupling model,seven reserve scenarios have been selected.From scenario one to scenario seven,the trend of spatial distribution of ecosystem services is changing from low-value agglomeration to high-value agglomeration;considering the protection efficiency and trade off of ecosystem services,this paper selects scenario 5(Eimean>1,trade-off=0.68)as the priority protection area for ecosystem services in Wafangdian.(4)Construction of ecological security pattern.On the basis of identified priority protection area for ecosystem services,and with the support of “Patch-Corridor-Matrix” theory,this paper determines the ecological security pattern composed of three components including ecological source,ecological corridor and ecological buffer zone.The construction of ecological security pattern provides references for urban land use planning and adjustment.By further comparing with Master Plan of Land Use of Wafangdian 2006-2020 and spatial layout and area of each component of ecological security pattern,the paper gives suggestions for ecological system management in different areas and grades,and expects to provide scientific guidance for social and ecological developments and the construction of ecological civilization for cities along coastal zones.