【作者】 朱江；

【导师】 周生路；

【作者基本信息】 南京大学 ， 地理学， 2020， 博士

【摘要】 土地不仅是人类社会与自然环境相互作用的动态界面,也是自然社会复杂自适应性系统。21世纪以来,快速的城镇化进程对国土资源空间进行了高强度的开发利用,造成了耕地与粮食安全威胁、环境污染破坏和生态系统退化等日益突出的人地矛盾。在此背景下,通过国土空间综合规划,加强国土资源的数量、质量和生态“三位一体”管理,实现面向生态文明的城镇化已成为近年来的研究热点。现有研究从土地生态评价与管控、土地生态系统与城镇化耦合等方面开展了较多工作,但大多数研究对土地的理解还局限于狭义上的土地资源,而对土地的人地系统综合性和生态文明自然社会综合性仍认识不足。我国未来仍处于推进城镇化和生态文明建设的关键时期,日益增长的国土空间开发利用将会带来各类人地矛盾剧增的风险。以系统性思维拓宽土地问题研究视角,并开展城镇化背景下土地生态风险系统性综合评价、响应与管控研究,对于完善土地生态风险评价研究理论体系、优化城镇化对土地生态的作用机制、推动区域可持续发展具有重要意义。论文依托原国土资源部公益性行业科研专项项目(201511001-03)和江苏省原国土资源厅科技计划项目(201336),以正在经历城镇快速扩张进程的沿海发展国家战略实施典型县,国家首批可持续发展实验区重要组成部分的江苏省射阳县为案例研究区,基于土地系统科学、景观可持续科学和脆弱-可持续性理论等,探讨了区域城镇化进程中土地生态风险研究的理论内涵和方法创新。首先,基于理论分析从风险来源、风险受体和风险效应的作用关系,构建了土地生态风险的系统性综合评价框架,在遥感解译、模型计算和实地调研等多途径集成建立的数据库基础上,提出了沿海地区土地生态风险系统性综合评价的具体指标体系,定量评估了研究区土地生态风险,并基于Moran’s I和冷热点分析等方法量化了其空间格局。其次,构建指标体系量化了研究区城镇化的空间格局,针对研究区城镇化水平整体不高但空间差异显著的特点,基于空间换时间的方法,利用梯度分析以及脱钩模型多角度多方法研究了土地生态风险对城镇化水平的响应机制。随后构建风险约束性元胞自动机模型,开展了趋势情景、自然风险约束情景、社会风险约束情景和综合风险约束情景等多情景下的城镇建设用地扩张动态模拟,分析了不同情景下城镇建设用地扩张的时空差异和相应土地生态风险变化等。最后,以土地生态风险指数的空间分布格局为基础,按照城镇发展与土地生态保护相协调等原则,基于多维空间聚类等对研究区土地生态风险管控进行综合分区,并进行差别化土地资源开发利用政策设计。论文得出以下主要结论:(1)论文以“风险来源-风险受体-系统恢复力-系统损失度”关系链构建了土地生态风险系统性综合评价框架,从风险来源、土地生态抵御风险的能力和潜在影响对土地生态风险进行系统性、定量化的空间精细化表达,结果表明该土地生态风险评价框架能够精细化地评估沿海地区土地生态风险状况,具有较高的空间精度。研究区土地生态风险在空间上存在较明显的异质性,东南沿海地区多为湿地滩涂,生态系统脆弱,自然风险指数最高,综合风险指数显著高于其他地区,不适宜大规模的开发利用。中西部地区综合风险指数较低,生态系统压力小,具有较大的发展潜力。此外,自然风险与社会风险的交叉分析结果显示两者间无显著相关关系,表明土地生态风险评估时需要同时考虑自然和社会这两个维度。风险评估结果与实地调查结果以及射阳县城总体规划方案基本一致,表明对于土地生态风险的评价,不能仅考虑生态环境方面,而应该全面考虑自然风险和社会风险,并从风险来源、风险受体和风险效应等方面综合量化人地过程中的土地生态风险。(2)研究区土地生态风险对城镇化水平的梯度响应和脱钩响应存在显著的空间分异。土地生态风险对城镇化水平的梯度响应表现为“城镇中心-城郊结合区-郊区-边缘地区”的梯度变化,在西-东、南-北、西南-东北和东南-西北4条样带上,土地生态自然风险、社会风险、综合风险对城镇化的响应均为波动变化;在环形梯度上,土地生态社会风险以及综合风险呈现中间低、周围高的格局。基于圈层梯度“空间换时间”的脱钩分析表明,城镇化过程中土地生态风险与城镇化水平趋于脱钩,其中,土地生态自然风险趋于强脱钩,土地生态社会风险趋于弱脱钩,土地生态综合风险的脱钩状态取决于两个维度的交互作用。逆城镇化过程中土地生态社会风险、综合风险与城镇化水平趋于复钩,土地生态自然风险与城镇化水平趋于脱钩。城镇化和逆城镇化过程中,都存在土地生态风险与城镇化良性发展的可能性。(3)多风险约束情景下研究区城镇建设用地将持续扩张,城市和中心镇集群效应显著,研究区城镇发展宜采用双中心模式。论文采用适宜性风险约束CA模型,模拟分析了环境适宜性约束情景、自然风险约束情景、社会风险约束情景和综合风险约束情景下的城镇建设用地扩张情况和土地生态风险变化。结果显示,2013-2030年,研究区城镇建设用地面积将从43.50 km~2增长到96.75-105.00km~2,扩张至2.22-2.41倍,年均增长3.13-3.62 km~2。社会风险约束情景下的城镇建设用地增长最多,城镇化造成的土地生态风险最小;自然风险约束情景下城镇建设用地增长最少,土地生态风险指数高值所占比例较大。结果表明传统的环境适宜性约束CA模型会高估城镇化潜力,因其未考虑土地生态的弹性和潜在影响,也忽视了生态风险的社会维度。随着城镇化进程的推进,研究区城镇化模式应从大城镇扩张转向综合风险约束下的双中心模式。(4)以土地生态风险指数的空间分布格局为基础,基于多维空间聚类等将研究区划分成3个一级类型风险管控区和9个二级管控亚区,促进区域生态风险精准管控。按照城镇发展与土地生态保护相协调等原则,为确定土地生态风险的主导来源和管控方向,一级类型风险管控区划分成城镇发展建设土地生态风险管控区、农用地保护优化土地生态风险管控区和国家级珍禽保护土地生态风险管控区。为进一步提升风险管控精细化水平,分别根据城镇发展定位、土地生态风险强度差异、生物保护强度差异进行二级管控亚区划分。综合来看,研究区大部分地区为农用地保护优化风险管控区,其中东部区域的自然社会综合条件较好,适宜在保障农业生产的基础上进行一定的城镇发展。城镇发展建设风险管控区主要以合德镇为中心,包含周围几个中心镇的部分区域,该风险管控区是射阳县的经济社会发展中心,面临着一定程度的土地生态压力,未来应注重优化土地利用方式,促进城镇景观可持续发展。国家级珍禽保护风险管控区位于射阳县东部沿海地区,主要包括丹顶鹤栖息地,该区域自然环境良好,未来发展规划需尽量减少人类活动干扰。基于区域土地生态风险状况、不同风险约束情景下的未来城镇建设用地扩张模拟和土地生态风险对比结果,综合提出的土地利用分区开发政策,对于射阳县土地生态风险管控而言更具有实用性和可操作性,是开展生态环境治理、发展社会经济以及促进区域协调可持续发展的重要保障。更多还原

【Abstract】 Land,as the dynamic interface of human-environment interactions,is a complex adaptive human-environment system.Along with China’s rapid urbanization since the twenty-first century,the land systems in China have been intensively developed across the whole country,leading to severe human-environment problems such as farmland loss and consequent threats on food security,environment pollution,and ecological degradation.In this context,a recent research hotspot has been the comprehensive land use planning to enhance the integrated land management based on the three dimensions of quantity-quality-ecology,such that existing urbanization practices in China can be navigated toward ecological civilization.In this vein,notable research progress has been made on land ecological assessment and management as well as the coupling between the land ecological system and urbanization.However,in general,existing studies often take the narrow conceptualization of land as resource and treat ecological civilization as merely eco-environment protection and construction.While the understanding of land as integrated human-environment system and ecological civilization as comprehensive human-environment sustainability remains greatly underappreciated.In the upcoming decades,China will be at a critical stage of promoting urbanization and ecological civilization,when increasingly intensified land development is expected to cause soaring human-environment problems of various kinds.Those problems will be particularly prominent in China’s coastal areas where socioeconomic development is among the most intensive.Therefore,it is timely and significant to conduct comprehensive studies on the assessment,response,and management of land ecological risk in urbanizing coastal areas,by taking the extended human-environment systems perspective on land.Such studies will contribute to developing theories for land ecological risks assessment and informing policy design for navigating the feedback loops of urbanization-land systems such that the sustainability transition can be achieved in urbanizing coastal areas.The present doctoral research is financially supported by the Special Research Funds for Public Welfare from formerly the Ministry of Land and Resources of China(No.201511001-03)and the R&D Project from formerly the Administration of Land and Resources,Jiangsu Province of China(No.201336),with an empirical focus on Sheyang County,Jiangsu Province.Sheyang is a county typical in the coastal zone of China with rapid urban expansion,and is also part of the China’s first few Sustainable Development Experimental Zones.With theoretical insights from land system science,landscape sustainability science and the vulnerability-sustainability theory,this study explored the ontological and epistemological foundations of and attempted methodological innovations for assessing land ecological risks in the context of urbanization.Firstly,a theoretical framework for assessing land ecological risks was constructed,based on analysis of the relationships between risk sources,human-environment context,risk suffers,and risk impacts.To operationalize this framework,a localized indicator system was proposed based on remote sensing,model simulation,and field investigations,for assessing the land ecological risks in urbanizing coastal areas.The indicator system was applied to our case study area of Sheyang,based on which we quantified the spatial pattern of Sheyang’s urbanization-associated land ecological risks using Moran’s I and hot/cold spots analyses.Secondly,according to the characteristics that the overall urbanization level of the study area is not high but the spatial variation is significant,based on the trading space for time,the mechanisms of land ecological risks’response to urbanization was examined by the rural-urban gradient analysis and decoupling analysis.To these ends,the urbanization level across Sheyang was assessed based on an indicator system,following which were the examination of the correlation between land ecological risks and urbanization dynamics based on the transect-based and ring-based rural-urban gradients and the decoupling model.Thirdly,a risk-constrained cellular automata(CA)model was developed for land system dynamics simulations in four scenarios:business-as-usual(i.e.,environmental suitability constrained),ecological risk constrained,social risk constrained,and social-ecological risk constrained scenarios.The simulations revealed contrasting spatiotemporal patterns of urban expansion and associated land ecological risks in the different scenarios.Finally,based on the principle of reconciling urban development and land system protection and also on the spatial pattern of the land ecological risks,integrated zoning of the study area was conducted via multi-dimensional spatial clustering for management of the urbanization-associated land ecological risks.The findings of this dissertation are as follows:(1)A comprehensive framework for assessing land ecological risks was proposed based on the three components for the genesis of land ecological risks:risk sources,social-ecological resilience,and potential social-ecological impacts.Results show that the proposed framework facilitated the precise,quantitative assessment of land ecological risks,with relatively high spatial resolution.The land ecological risks of the study area presented notable spatial heterogeneity,displaying a pattern of large in the southeast while small in the northwest.The southeast coast part is mainly the fragile ecosystem of wetland or tidal flat,with the largest ecological risk score and notably larger social-ecological risk score,unsuitable for large-scale development.The central and west parts are of large potential for development,thanks to the relatively small social-ecological risk resulting from small disturbances on the ecological subsystem.Besides,cross-analysis of the social risk and ecological risk at the grid scale show that there is no significant relationship between the two,suggesting the need of considering both in the assessment of land ecological risks.The assessment result of Sheyang accords well with field investigation and Sheyang’s master land use plan,indicating that,in addition to the eco-environmental dimension,the social dimension should also be incorporated for comprehensive assessment of land ecological risks by considering simultaneously risk sources,system resilience,and potential social-ecological impacts.(2)Notable spatial differentiation of the study area existed in the gradient and decoupling responses of land ecological risks to urbanization.Land ecological risks showed a gradient response to urbanization level,increasing from urban center to urban-suburban interface,and to suburban and finally to the periphery.Specifically,the transect-based gradients,i.e.,west-east,south-north,southwest-northeast,and southeast-northwest,show fluctuated response patterns of the natural,social,and comprehensive land ecological risks to urbanization,while the ring-based gradient shows a response pattern of“low in the core while high in the periphery”for both the social and comprehensive land ecological risks.Further,the ring-based urbanization gradients were adopted for analyzing the decoupling between land ecological risks and the urbanization process based on the idea of“space-in-substitution-of-time”.During urbanization,land ecological risks tend to decouple with urbanization level,among which the natural land ecological risk tends to become strongly decoupled and social land ecological risk weakly decoupled,while decoupling of the comprehensive land ecological risk is determined by interaction of the natural and social dimensions.During counter-urbanization,the social and comprehensive land ecological risks tend to get negatively decoupled with urbanization level,while the natural land ecological risk is more inclined to be decoupled.The results show that sustainable development of urbanization and land ecology is possible during counter-/urbanization.(3)A risk-constrained CA model was developed for scenario-based simulations of the urban growth and land ecological risk responses in Sheyang.In multiple scenarios,the study area will undergo continued urban expansion with notable agglomeration around existing urban centers,which suggests a biocentric urban development strategy for the study area.Specifically,the following four risk-constraint scenarios were considered:environmental suitability constrained,natural risks constrained,social risks constrained,and natural-social risks constrained.The simulations show that,from 2013 to 2030,the urban construction land area of Shyeyang will increase from 43.50 km~2by 2.22-2.42 times to 96.75-105.00 km~2,with an annual growth of 3.13-3.62 km~2.Increase of the urban construction land area was simulated to be the largest in the social risks constrained scenario with the least urbanization-induced land ecological risks;while the smallest in the natural risks constrained scenario with a larger percentage of high land ecological risk grids.The simulations suggest that considering only environmental suitability in the CA simulations of urban development,as long-practiced in the conventional CA models,would overestimate the potential of sustainable urban growth,because the system resilience and potential impacts are not considered in the conventional models,nor is the social dimension of land ecological risks considered.Moreover,the simulation results of Sheyang imply that that the urbanization mode of Sheyang should change from the monocentric urban development as dominated by downtown Sheyang to bicentric urban development as constrained by integrated land ecological risks.(4)Based on the spatial pattern of land ecological risks,a multi-dimensional spatial clustering method was used for the spatially-precise risk-management of the study area,resulting to three first-level management zones and nine second-level zones.Following the principle of reconciling urban development and land system protection,the three first-level zones for land ecological risks management include the urban development and construction zone,the agriculture protection and optimization zone,and the national rare-bird conservation zone,each with different dominant source of land ecological risks and corresponding management strategies.To further implement fine management,the nine second-level zones were distinguished based on urban development niche,land ecological risk intensity,and biodiversity conservation.In general,most of the study area falls into the agriculture protection and optimization zone.Specifically,the east part,with relatively advantaged social-ecological conditions,is suitable for conservative urban development on the basis of guaranteeing agricultural production.The areas for urban development and construction include Hede town as a growth center and its surrounding major towns.Those risk-management zones are the socioeconomic hotspots of Sheyang,facing land system pressures to some extent,and thus should invest efforts in optimizing land use structure to promote urban landscape sustainability.The national rare bird-preservation zone is located in mainly the east coastal part of Sheyang,including especially the red-crowned crane habitat.Those areas have great eco-environment and should be better planned to prevent from intensive human disturbances.The proposed land use zoning and management policies are based on regional land system status quo and the contrast patterns of urban growth and land ecological risk assessment in different simulation scenarios,and are thus expected to be more practical and operable.This methodological approach is effective for implementing eco-environmental governance,promoting socioeconomic development,and transitioning toward regionally coordinated sustainable development.更多还原