| Since the reform and opening up,China’s industrialization and urbanization have entered a stage of rapid development,with unprecedented growth in economic scale and population size,and extraordinary achievements in social and economic development.However,the long-term way of development at the cost of excessive consumption of resources and sacrificing the environment has caused many urban ecological and environmental problems such as environmental pollution,urban heat island,reduction of biodiversity,and resource exhaustion,which has gradually become an important bottleneck hindering the sustainable development of social economy.In order to solve the problem between development and protection,the strategic decision of ecological civilization development has gradually been established since the 17th CPC National Congress,which has pushed the issue of ecological environmental protection to a new historical height.As an important carrier of the natural ecosystem and social economic system,territorial space provides a place for the interactive evolution of various ecological and economic processes.Optimizing the territorial spatial pattern is not only a key measure to promote the development of ecological civilization,and but also a major strategic issue concerning the overall situation of China’s socio-economic development and the sustainable development of the Chinese Nation.Facing the new era background and development requirements of the construction of ecological civilization,it is urgent to draw on the theoretical knowledge and technical methods from multiple disciplines based on a comprehensive and systematic understanding of the law of the territorial spatial evolution and conduct integrated research on how to facilitate the harmonious development of economy and ecology through the orderly development and rational layout of the territorial space.Ecosystem services are regarded as an important tool for strengthening the protection and management of ecosystems,optimizing the territorial spatial patterns,and promoting the development of ecological civilization because it can effectively couple natural and social processes.Therefore,under the advocacy of ecological civilization values,strengthening the coupling research of ecosystem service evaluation and territorial spatial optimization,and establishing a method system for optimizing the territorial spatial patterns to improve ecosystem services and ensure ecological security,have important significance for building a scientific,reasonable,moderately orderly,coordinated and efficient pattern of territorial spatial development and protection,and futher achieving the strategic target of ecological civilization.Therefore,to meet the requirements of the era for the optimization of territorial space,building the territorial spatial patterns of development and protection that harmonizes urban space,agricultural space and ecological space,this study focuses on the application value of ecosystem services in the territorial spatial planning decision-making,and realizes the simulation and optimization of the territorial spatial patterns in Nanjing.Specifically:first of all,focusing on the research objectives of optimizing the territorial spatial patterns and improving ecosystem services,this paper finds the starting point by systematically combing and summarizing related literatures.The correlation mechanism between ecosystem services,ecological security patterns and the territorial spatial patterns was elaborated systematically,based on multi-disciplinary theories,including system science theory,man-land relationship theory,natural capital theory,sustainable development theory,landscape ecology theory,and optimal configuration of land resources theory.Then the logic context of territorial spatial pattern optimization was analyzed based on the“pressure-state-response”model.Secondly,taking Nanjing City as the study area,this paper discusses the related issues of optimizing the territorial spatial patterns by comprehensively using GIS spatial analysis,In VEST model,minimum cumulative resistance(MCR)model,multi-objective optimization model,land use change simulation,scenario analysis as well as other technical methods,and forms a spatial plan suitable for the development orientation of Nanjing.The main contents and conclusions of this paper are as follows:(1)Using remote sensing image as the source data,the spatio-temporal change characteristics of land use patterns in Nanjing from 2000 to 2018 are analyzed from the three aspects of quantitative structure,spatial form and utilization degree.Structural characteristics such as the quantity and direction of land use change are analyzed by transition matrix of the land use.The speed and magnitude characteristics of land use chang are analyzed according to the dynamic degree index of the land uses.The landscape pattern index and the migration model of gravity center are used to depict the spatial form of land use change.The comprehensive development and utilization level of land in the region is reflected by the index of land use degree.In the end,the evolution law of the territorial spatial patterns is further revealed by establishing the relationships between the three types of spaces and land use types.The results show that:Nanjing has experienced a relatively dramatic urbanization phenomenon during the past 18 years.The expansion of urban land is mainly from cultivated land and woodland.Although the water area fluctuates greatly during the study period,the overall change is small.The analysis results of landscape pattern index show that the landscape patterns at both the landscape level and patch level are characterized by increased fragmentation,complex patch shape and scattered distribution.From the perspective of spatial form,the urban development of Nanjing is greatly affected by the topography and geomorphology.The urban spatial layout conforms to the terrain constraints such as mountains,lakes,rivers,etc.,and is built in accordance with the mountain situation,which integrates the urban development pattern of Nanjing with the natural landscape,forming a unique style where mountains,water,forests and cities complement each other.From the perspective of the changes in the proportions of the three types of spaces,urban space has significantly expanded,with an average annual growth of 0.54%from 2000 to 2018,and the corresponding agricultural space has decreased the most,with an average annual decrease of0.52%.During the study period,the ecological space has also been reduced to some extent,with an average annual reduction of 0.06%.(2)On the basis of comprehensive consideration of the natural geographical conditions and ecological environment characteristics of Nanjing,three indicators including water retention service,carbon storage service and soil conservation service are selected to evaluate the current ecological environment of the city.Combined with the selected ecological sensitivity indices such as habitat sensitivity,geological hazard sensitivity,water environment sensitivity and soil erosion sensitivity,an index system for identifying ecological sources has been established.According to the selected ecological sources and the modified spatial resistance value,key landscape components which include ecological corridors and ecological strategic points are identified,then the comprehensive ecological security patterns is finally constructed.The results show that the total amount of water rentention in Nanjing is 9.70×10~8 m~3,and the average water retention per unit area is1479.04 m~3/hm~2.The water rentention service is closely related to land use types,and the land types with strong water retention capacity are woodland and grassland.Carbon storage has strong spatial heterogeneity due to the dual effects of vegetation distribution and soil properties,and the high value areas are mainly distributed in mountainous areas where forest land is relatively concentrated.From the perspective of land use types,the land use type with the largest scale of carbon sequestration is cultivated land,but the forest land has the strongest capacity of carbon sequestration.High value areas for soil conservation services are still concentrated in hills and mountains,and woodland and grassland have the strongest capacity of soil conservation.The selected ecological source area is 96680.54 hm~2,accounting for about 14.75%of the total area of Nanjing.It is mainly distributed in mountains and waters within the city,including landscape elements with important ecological functions such as Yangtze River,Purple Mountain,Ningzhen Mountains,Old Mountains,etc.The identified23 ecological corridors and 29 ecological nodes are roughly divided into four major groups in space,which are distributed in the eastern region,western region,southwestern region and southern region of Nanjing.Based on the research results,the optimization mode of ecological network layout of“one core and five zones,three horizontal and two vertical”is proposed.(3)According to the analysis of the historical trend of Nanjing urban development and the prediction of the uncertainty of future development,four scenarios,namely natural growth scenario,economic development scenario,ecological protection scenario and ecological economy balanced development scenario,are set based on different urban expansion speeds.On this basis,a combined function is constructed with the objective of ecosystem service value and the economic benefits of land use.The improvement of differentiated ecosystem services under three different scenarios(except for natural growth scenarios)is set as constraint conditions.And a multi-objective optimization model is constructed in combination with the constraint conditions on the amount of cultivated land,the amount of woodland and the scale of urban construction land.The multi-objective genetic algorithm(MOGA)toolbox in Matlab software is used to solve the structure of land use under the three development scenarios,then three types of spatial structures under different development scenarios are obtained.Results show that:there will be significant differences in the quantity and scale of the three types of spaces in 2035 under different scenarios.Compared with 2018,urban space will increase by 24.07%under the natural growth scenario,while agricultural space and ecological space will decrease by 0.56%and 16.47%,respectively.Under the economic development scenario,on the basis of 2018,urban space and ecological space will increase by 25.68%and 21.72%,respectively,while agricultural space will decrease by 13.35%.Under the ecological protection scenario,compared with2018,the urban space and ecological space will increase by 9.89%and 32.66%,respectively,while the agricultural space will decrease by 13.02%.Under the ecological economy balanced development scenario,urban space and ecological space will increase by 19.20%and 24.25%,respectively,while agricultural space will decrease by 12.57%.(4)Based on the analysis of the driving mechanism of regional land use change,13driving factors are selected,and the logistic regression model is used to reveal the effect of each driving factor on land use change in Nanjing City.Taking into account the different development models and ecological protection intensity of the city in the future,the FLUS model is used to simulate the territorial spatial patterns under four scenarios,and the optimal scenario of urban development is determined from the three perspectives of construction suitability,ecological safety and space compactness.According to the optimal development scenario,combined with the constructed ecological security patterns and a morphological technology based on erosion and dilation algorithm,the rigid boundary and elastic boundary of urban development are delineated,respectively.Finally,in accordance with the optimization scheme of territorial spatial patterns designed by the research,the corresponding countermeasures and suggestions for spatial development and reulation are put forward.Results show that:the influential direction and intensity of different driving factors on the changes of various land use types are quite different.Although the expansion speed of urban space under different scenarios is different,they all extend along the east-west direction with the Yangtze River as the axis.Among them,the Jiangbei New Area would be a hot spot for future urban development.In the above four scenarios,agricultural space is affected by the expansion of urban space and ecological space,showing a downward trend and gradually fragmenting.The ecological space is mainly distributed in clusters of low mountains and hills,lakes,rivers and wetlands.Among them,the ecological space has the highest degree of contiguousness under the ecological protection scenario.Through the comparative analysis of different development scenarios in the region,it is found that the territorial spatial patterns under the ecological protection scenario would be the most suitable for the future development orientation of Nanjing City.Based on the results of the delineation of the ecological security patterns,the scale of the rigid boundary of urban development is361957.78 hm~2,which defines the spatial scope of ecological protection.Using the erosion and dilation algorithms,the scale of the elastic boundary of urban development is 117079.83hm~2,which defines the expansion direction of urban space.A set of urban development boundary system with reasonable scale,clear boundaries and easy management is finally formed through the combination of rigid boundary and elastic boundary.Based on this,considering the realistic demands of Nanjing urban development and the policy needs of spatial regulation,the realization paths and control countermeasures of territorial spatial pattern optimization are designed. 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