城市土地利用变化对生态系统服务的影响——以淮北市为例

城市是一类以人类活动为中心的社会-经济-自然复合生态系统.城市的快速蔓延及强烈的人类活动显著地改变了城市的土地利用结构,进而严重影响了城市生态系统服务及人居环境.通过遥感、GIS技术及生态系统服务价值评估等方法,对淮北市1987年、2000年和2007年3个时期20a间的土地利用结构及生态系统服务价值的演变进行定量评价.研究结果表明:1987-2007年间淮北市生态用地空间结构和面积发生剧烈变化,生态用地占城市面积的比例由91.45％降低至71.86％.1987-2000年,农田面积大幅度下降,而林地和水体都呈不同程度的增加趋势,建设用地面积增长迅速.2000-2007年,农田面积有所增加,林地和水体面积却明显下降,建设用地总面积虽然没有明显变化,但其聚集度显著增加.20年间,城市生态服务功能的价值呈现先增加后减少的趋势,在2000年达31.32亿元.2000-2007年,以废物处理和水源涵养功能退化最为严重.可见,城市土地利用结构的变化与生态服务功能密切相关,此结果可为淮北市景观格局优化及土地合理调控和管理提供一定的科学依据.     

厦门市土地利用变化下的生态敏感性

当前,城市化与全球变化背景叠加,海岸带生态系统发生了巨大的变化,沿海城市在全球变化下的脆弱性、敏感性与适应能力等问题已经成为政府和科学界关注的重要问题.土地利用变化是导致生态系统敏感性的重要因素之一.以厦门市作为沿海城市的典型代表,对近20 a土地利用变化下的生态敏感性进行系统研究.分析了城市建设用地扩张、围填海等主要土地利用活动对生态敏感性的影响机制;其次建立土地利用变化下的生态敏感性指数,并分析其变化过程;最后通过ArcGIS图层叠加计算功能,获得生态敏感性空间分布状况.结果表明:1987-2007年厦门市城市建设用地面积由1987年的67.48 km2,增加为2007年的308.21 km2,扩张了4.57倍,主要为蚕食农业用地和林地而来;海岸线长度由1987年的290.19 km,增加为1992年的343.23 km,而后减小为2007年的299.93 km,围垦养殖活动使得岸线变得曲折,填海造地活动导致岸线变得平滑.厦门市土地利用强度由1987年的2.44逐年增加为2007年的2.52,生态系统服务价值总体呈现减小的趋势,由1987年的7.39×109元减少到2007年的7.02× 109元,土地利用强度与生态系统服务价值呈现负相关关系.土地利用变化下的生态敏感性指数由1992年的1.50增加为1997年的4.94,而后减小为2002年的4.12,再增加为2007年的4.47.整体而言,近20a来厦门市生态系统对土地利用变化的敏感性灵敏响应程度不很剧烈,生态敏感性高的区域主要位于沿海区域.     

西北干旱区生态脆弱性时空演变分析

西部大开发政策实施以来,随着社会经济的发展和环境政策的调整,西北干旱区生态环境发生深刻变化。基于西北干旱区生态本底特征,选取土壤、地形、气候并结合夜间灯光数据构建西北干旱区生态脆弱性评价体系,运用空间主成分分析法（SPCA）、地理探测器对西北干旱区2000、2007、2012、2018年生态脆弱性时空演变及驱动力进行分析。结果表明：（1）从西北干旱区生态脆弱性时空演变特征来看,研究区生态脆弱性以重度脆弱性为主;从不同土地利用脆弱性来看,微度脆弱区以草地、林地为主,轻度脆弱区以草地为主,中度脆弱区和重度脆弱区以未利用地为主,18年来研究区生态脆弱性整体保持不变;（2）影响西北干旱区生态脆弱性分异的主导因素包括土壤有机质含量、地形位指数、气温、降水、夜间灯光指数,各因素对生态脆弱性的平均决定力分别为0.63、0.36、0.27、0.26和0.22。（3）基于生态脆弱性监测结果和驱动因素分析,将西北干旱区划分为5个生态功能区：生态核心保护区、生态综合监测区、生态优化关注区、生态恢复治理区、生态潜在治理区,并提出相应管理方案。研究可以为干旱区生态环境保护提供借鉴。     

重庆市土地利用冲突多尺度时空演化与多情景演化模拟

土地利用冲突是区域土地开发利用过程中存在的客观问题,对区域经济社会发展和生态安全具有重要影响。识别、测度区域土地利用冲突,明晰其时空演化格局,有助于优化区域土地利用结构,促进土地资源的可持续利用。以重庆市为例,基于景观格局构建了土地利用冲突测度模型,从县域、镇域以及格网3个尺度全面和系统地分析了1995-2020年重庆市土地利用冲突的时空演化特征,并耦合多目标规划(Multi-Objective Programming,MOP)-斑块生成土地利用变化模拟模型(Ptach-generating Land Use Simulation,PLUS)模拟了重庆市2030年不同发展情景下土地利用冲突格局。结果表明:(1)1995-2020年重庆市县域、镇域与格网不同尺度下的土地利用冲突格局具有较大相似性,不同尺度的土地利用重度冲突区主要分布在重庆中心城区及周边地区,区县建成区。土地利用一般冲突区主要分布于渝东南和渝东北地区。研究期内土地利用冲突有所加剧,其中土地利用重度冲突区占比增加了3.09%。(2) 1995-2005年重庆市土地利用冲突区主体位于乡村地域,但冲突程度较低,随着工业化、城市化进程及人口的集聚,2005年后土地利用冲突热点区域的城市地域集聚效应显著,城市及周边地区土地利用冲突区面积和土地利用冲突度均显著提升。(3) 区域土地利用冲突空间格局不仅受到了人为经济社会活动的驱动影响,在空间格局上受自然生态环境基底影响显著,其中地形地貌的限制加剧了土地利用重度冲突区。(4)不同发展情景模拟中经济优先发展情景下土地利用冲突最为严重,生态优先发展情景下土地利用冲突最小,可持续发展情景兼顾了经济和生态发展的用地需求,土地利用冲突强度处于中间范围,但区域发展总福利最大,是未来区域发展路径最优选择。     

Assessing the impact of ecological and economic factors on land degradation vulnerability through multiway analysis

Land degradation (LD) is a global problem which involves climate, soil, vegetation, economic, and population conditions. In Mediterranean Europe climatic variability and human pressure combine to produce soil sealing, erosion, salinisation, fire risk, and landscape fragmentation, all regarded as important factors to start LD. The aim of this paper is to introduce a time-series evaluation of land vulnerability to degradation based on nine ecological and economic variables. The analysis was carried out over 1970–2000 at the municipality level in Latium (central Italy), a region which has shown increasing land vulnerability in the last years. A multiway data analysis (MDA) was applied in order to explore the relationship among indicators over the study period. Their importance in determining LD vulnerability was estimated through a weighting system based on MDA results. A composite index of land vulnerability (LVI) was obtained as the weighted average of the nine variables transformed into single indicators, according to their relationship with LD. Considerable increases in LVI were observed in dry coastal and lowland municipalities close to Rome, thus indicating that climate aridity, population growth, and land use changes are important determinants of land vulnerability in Latium. LVI was positively correlated to the environmental sensitive area index (ESAI) measured on the same spatial and time scales, thus suggesting that a sound evaluation of land vulnerability is possible through LVI score.     

城市综合生态风险评价——以淮北市城区为例

城市面临复杂的生态风险,为了保障城市安全,需要对单一灾害或污染源的生态风险评估结果进行整合。基于城市复合生态系统特性,将当前城市地域常见的生态风险区分为自然灾害、环境污染及生态退化等3种主要类型,以土地利用单元作为风险受体,整合自然、人文、景观及环境因子,在现有生态风险评价研究方法基础上,构建了城市综合生态风险评价的空间分析框架。研究中选择淮北市城区作为研究区,针对研究区内存在的洪涝、干旱、水污染、大气污染、采煤塌陷及生态服务降低等生态风险类型,定量评价其空间差异,并提出相应的风险防范措施。案例分析结果表明,研究区综合生态风险较高的区域包括龙河、岱河、龙岱河与闸河等过境河流流经塌陷密集带的河段,北湖、东湖、中湖及南湖等人工湖泊沿岸,化家湖湖岸,及土型、新蔡、北杨新杨煤矿及其外围地区。由降低生态风险保障城市生态安全角度,在未来城市的整体规划中,建议结合城市外围绿地与城市内部的高风险区域,划设禁建或限建区域,共同构建淮北城市生态风险防范的空间结构。     

快速城镇化过程中的城市蔓延与生态保护冲突空间识别与量化评估——以长三角生态绿色一体化发展示范区为例

如何解决社会经济发展与生态环境保护之间的矛盾是实现区域和城市可持续发展的首要问题,表现在空间上就是城市无序蔓延与生态环境保护用地的冲突,本质上是建成区与非建成区的生态系统之间的冲突。以长三角生态绿色一体化发展示范区为例,基于自然环境因子和社会经济因子构建城市蔓延风险空间量化评估模型,得到城市蔓延风险空间分布并提取城市蔓延严重风险区;利用生态侵蚀度指数识别评估生态保护压力空间并提取生态保护压力高值区。根据城市蔓延严重风险区与生态保护压力高值区的重合空间,对城市无序蔓延与生态保护的冲突程度进行分析,进而探讨快速城镇化发展过程中二者的协调关系,为城市国土空间规划与区域生态保护决策提供科技支撑。长三角生态绿色一体化发展示范区案例研究结果表明:(1)城市蔓延的严重风险区与生态保护压力高值区的重合面积达到583.83km~2;其中较高风险区与侵蚀度高的地区重合面积为311.73km~2,冲突度为53.39%;高风险区与侵蚀度高的地区重合面积为47.70 km~2,冲突度为8.17%。(2)示范区内各类生态系统中,耕地生态系统受城市蔓延冲突程度均为最高,其在较高和高风险区的占比分别为91.58%、8...     

Landscape transformation after irrigation development in and around a semi-arid wetland ecosystem

The objectives of this study are to determine the spatial and temporal land use/cover changes in a semi-arid agricultural basin (Develi Basin) after the implementation of an irrigation project and to understand how these changes affected the wetlands (Sultan Marshes) located in the basin. The changes were determined using multitemporal Landsat Thematic Mapper and Landsat 8 Operational Land Imager imagery taken in 1987, 1998, 2007, and 2013. The images were classified into six information classes (grasslands/shrublands, croplands, permanent wetlands, water bodies, barren, and urban/built-up) using a hybrid classification method. Post-classification change detection was applied to determine the changes between different years. Overall, the accuracy of the classified images ranged from 85 to 94%. Grasslands/shrublands covered the largest area in the basin (63% in 2013), followed by croplands (32% in 2013). The area covered by water bodies, permanent wetlands, barren, and urban/built-up was 5% (in 2013). From 1987 to 2013, croplands expanded by 56%, while grasslands/shrublands declined by 15%. The areas occupied by water bodies decreased by 88% and permanent wetlands decreased by 4%. Urban/built-up areas expanded by 140%. The hydrologic regime of the Sultan Marshes wetland changed, which resulted in declines in water volumes by 85% and in water inflows by 55% from 2000 to 2015. Climatic variations during the 1987–2013 period were low and there was no apparent trend in precipitation and air temperature, which ruled out climatic conditions as one of the drivers of wetland changes. Economic and institutional factors supported the expansion of irrigated agriculture and animal husbandry in the basin and accelerated the expansion of croplands and conversion to industrial and fodder crops and orchards from traditional non-irrigated crops. Expansion of croplands and irrigated agriculture were the major drivers of the changes in the Sultan Marshes.

     

经济快速增长区建筑用地变化及其对生态质量的影响——以福建晋江为例

改革开放以来,中国经济增长促进了建筑用地的快速增加,并在很大程度上影响着区域生态质量.本文以东南沿海经济快速增长的福建省晋江市为例,利用遥感技术重点研究经济快速增长导致的建筑用地变化及其对区域生态质量的影响.基于晋江市1996和2015年的Landsat遥感影像,利用建筑用地指数(IBI)提取建筑用地信息,并进行建筑用地变化分析;同时利用遥感生态指数(RSEI)对生态质量进行评价,定量分析城镇建筑用地变化与生态质量变化之间的关系.结果表明: 1996—2015年,晋江市建筑用地面积共增加68.54 km²,增幅达45%,建筑用地扩展强度为0.55.建筑用地的增加导致该市生态质量总体下降,RSEI均值从1996年的0.532下降到2015年的0.460,降幅达13.5%;生态优良等级所占面积的比例从1996年的39%下降到 2015年的21%.建筑用地扩展强度与生态质量呈显著负相关关系.     

关中平原城市群扩张对生态用地的多尺度影响

城市扩张与生态空间保护的矛盾是新型城镇化和国土空间规划过程中急需解决的问题之一。作为黄河流域生态保护与高质量发展的核心区域,关中平原城市群面临更加严峻的生态和资源胁迫。但相关研究主要对研究区整体的生态环境变化进行测度,少有研究分析城市群发展对生态用地的多尺度影响,且忽略了城市群中土地变化最剧烈,生态受胁迫最严重的城市边缘区。因此,基于土地利用数据,结合土地利用转移矩阵、景观指数、估算城市扩张间接影响的生态用地面积等方法,研究从城市群、重点城市和主要城市边缘区3个尺度分析1990-2018年城镇扩张对生态用地的直接和间接影响。结果表明：（1）关中平原城市群土地利用类型以半生态用地（耕地）为主,面积占比超过40%。而城市边缘区主要以半生态用地和建设用地为主。1990-2018年城市群建设用地面积比例由3.67%增长至5.93%,耕地面积共计减少3032.11 km²,自然生态用地的面积增加628.03 km²。受耕地占补、退耕还林等多重政策的影响,半生态用地和自然生态用地的变化呈现为"拉锯式"发展特征。（2）城市扩张对半生态用地的直接影响大于对自然生态用地的直接影响,各尺度土地利用转移变化大同小异,新增建设用地的主要来源均为耕地,其中城市边缘区的耕地受城镇扩张的挤占最为突出。（3）城市扩张对自然生态用地的间接影响大于直接影响,且不同城市建设用地对自然生态用地的间接影响因耕地补偿机制的不同而有所差异。因此,对关中平原城市群实施"一刀切"的耕地补偿政策实际上并不合理,应当因地制宜,考虑地区土地资源条件,适当调整发展和约束政策,更有利于城市群的可持续发展。     

深圳市龙华地区快速城市化过程中的景观结构研究：城市建设用地？…

利用多时段景观遥感制图信息和景观格局研究方法,对深圳市龙华地区快速城市化过程中城镇建成区和新开发区两种建设用地类型的结构和空间分布特征进行了研究,结果表明,两种类型研究期间斑块数量、平均面积大幅度增加,碎裂化程度不断降低;建成区增长主要有大型居民点持续扩张和独立小斑块不断产生两种模式。开发区建设的高峰时期是１９９０－１９９４年;受地形和交通等因素的影响,建成区一直表现出显著宏观异质性分布特征,但孔     

深圳市龙华地区快速城市化过程中的景观结构研究——城市建设用地结构及异质性特征分析

利用多时段景观遥感制图信息和景观格局研究方法,对深圳市龙华地区快速城市化过程中城镇建成区和新开发区两种建设用地类型的结构和空间分布特征进行了研究.结果表明,两种类型研究期间斑块数量、平均面积大幅度增加,碎裂化程度不断降低;建成区增长主要有大型居民点持续扩张和独立小斑块不断产生两种模式,开发区建设的高峰时期是1990～1994年;受地形和交通等因素的影响,建成区一直表现出显著宏观异质性分布特征,但孔隙度水平不断降低,中小尺度的分布差异仍然比较明显;新开发区受与建成区相同的约束条件限制,同样表现为宏观异质性特征,空间不均匀分布的表现尺度大于建成区.工作区内因城建用地快速膨胀引起的各种生态问题急需通过土利用政策的调整加以解决.     

Development and Applications of a Comprehensive Land Use Classification and Map for the US

Land cover maps reasonably depict areas that are strongly converted by human activities, but typically are unable to resolve low-density but widespread development patterns. Data products specifically designed to resolve land uses complement land cover datasets and likely improve our ability to understand the extent and complexity of human modification. Methods for developing a comprehensive land use classification system are described, and a map of land use for the conterminous United States is presented to reveal what we are doing on the land. The comprehensive, detailed and high-resolution dataset was developed through spatial analysis of nearly two-dozen publicly-available, national spatial datasets – predominately based on census housing, employment, and infrastructure, as well as land cover from satellite imagery. This effort resulted in 79 land use classes that fit within five main land use groups: built-up, production, recreation, conservation, and water. Key findings from this study are that built-up areas occupy 13.6% of mainland US, but that the majority of this occurs as low-density exurban/rural residential (9.1% of the US), while more intensive built-up land uses occupy 4.5%. For every acre of urban and suburban residential land, there are 0.13 commercial, 0.07 industrial, 0.48 institutional, and 0.29 acres of interstates/highways. This database can be used to address a variety of natural resource applications, and I provide three examples here: an entropy index of the diversity of land uses for smart-growth planning, a power-law scaling of metropolitan area population to developed footprint, and identifying potential conflict areas by delineating the urban interface.     

Land cover dynamics of different topographic conditions in Beijing,China

Topographic conditions play an important role in controlling land cover dynamic processes.In this study,remotely sensed data and the geographic information system were applied to analyze the changes in land cover along topographic gradients from 1978 to 2001 in Beijing,a rapidly urbanized mega city in China.The study was based on five periods of land cover maps derived from remotely sensed data:Landsat MSS for 1978,Landsat TM for 1984,"1992,1996 and 2001,and the digital elevation model (DEM) derived from 1:250,000 topographic map.The whole area was divided into ten land cover types:conifer forest,broadleaf forest,mixed forest,shrub,brushwood,meadow,farmland,built-up,water body and bare land.The results are summarized as follows.(1) Shrub,forest,farmland and builtup consist of the main land cover types of the Beijing area.The most significant land cover change from 1978 to 2001 was the decrease of the farmland and expansion of the builtup area.Farmland decreased from 6354 to 3813 km2 in the 23 years,while the built-up area increased from 421 to 2642 km2.Meanwhile,the coverage of forest increased from 17.2% to 24.7% of the total area.The conversion matrix analysis indicated that the transformation of farmland to the built-up area was the most significant process and afforestation was the primary cause of the replacement of shrub to forest.(2) Topographic conditions are of great importance to the distribution of land cover types and the process of land cover changes.Elevation has an intensive impact on the distribution of land cover types.The area below 100 m mostly consists of farmland and built-up areas,while the area above 100 m is mainly covered by shrub and forest.Shrub has the maximum frequency in areas between 100 and 1000 m,while forest has dominance in areas above 800 m.According to the analysis of land cover changes in different ranges of elevation,the greatest change below 100 m was the process of urbanization.The process of the main land cover change occurred above 100 m was the transformation from shrub to forest.This result was consistent with the vertical change of natural vegetation distribution in Beijing.(3) Slope has a great influence on the distribution of land cover.Farmland and built-up areas are mostly distributed in fiat areas,while shrub and forest occupy steeper areas compared with other land cover types.Forest frequency increased with the increasing slope.Land cover changes differed from the slope gradients.In the plain area,the land cover change occurred as the result of urbanization.With the increasing of the slope gradient,afforestation,which converts shrub to forest,was the process of the primary land cover change.     

城市建成区土地利用的环境影响评价——以南昌市主城区为例

基于土地利用环境影响的相关研究和城市土地利用特点,构建了城市建成区土地利用环境影响评价的概念模型,将建成区土地利用环境影响评价总结为细化、抽象、对应和评价4个基本过程,并以南昌市主城区为研究对象,分析了该区噪声、气味、粉尘和危险4个因素对环境的影响.结果表明：研究区噪声的影响范围占研究区总面积的59%;气味和粉尘的影响主要集中在主城区的东部和南部地区;危险的影响范围主要集中在主城区的东南方向,是南昌市工业较集中的区域,影响面积达19.6 km².该模型将城市建成区环境影响评价分为4个基本过程是可行的,可为研究区土地管理、城市规划等相关政策的制定提供依据.     

Land cover dynamics of different topographic conditions in Beijing, China

Topographic conditions play an important role in controlling land cover dynamic processes. In this study, remotely sensed data and the geographic information system were applied to analyze the changes in land cover along topographic gradients from 1978 to 2001 in Beijing, a rapidly urbanized mega city in China. The study was based on five periods of land cover maps derived from remotely sensed data: Landsat MSS for 1978, Landsat TM for 1984, 1992, 1996 and 2001, and the digital elevation model (DEM) derived from 1:250,000 topographic map. The whole area was divided into ten land cover types: conifer forest, broadleaf forest, mixed forest, shrub, brushwood, meadow, farmland, built-up, water body and bare land. The results are summarized as follows. (1) Shrub, forest, farmland and builtup consist of the main land cover types of the Beijing area. The most significant land cover change from 1978 to 2001 was the decrease of the farmland and expansion of the builtup area. Farmland decreased from 6354 to 3813 km2 in the 23 years, while the built-up area increased from 421 to 2642 km2. Meanwhile, the coverage of forest increased from 17.2% to 24.7% of the total area. The conversion matrix analysis indicated that the transformation of farmland to the built-up area was the most significant process and afforestation was the primary cause of the replacement of shrub to forest. (2) Topographic conditions are of great importance to the distribution of land cover types and the process of land cover changes. Elevation has an intensive impact on the distribution of land cover types. The area below 100 m mostly consists of farmland and built-up areas, while the area above 100 m is mainly covered by shrub and forest. Shrub has the maximum frequency in areas between 100 and 1000 m, while forest has dominance in areas above 800 m. According to the analysis of land cover changes in different ranges of elevation, the greatest change below 100 m was the process of urbanization. The process of the main land cover change occurred above 100 m was the transformation from shrub to forest. This result was consistent with the vertical change of natural vegetation distribution in Beijing. (3) Slope has a great influence on the distribution of land cover. Farmland and built-up areas are mostly distributed in flat areas, while shrub and forest occupy steeper areas compared with other land cover types. Forest frequency increased with the increasing slope. Land cover changes differed from the slope gradients. In the plain area, the land cover change occurred as the result of urbanization. With the increasing of the slope gradient, afforestation, which converts shrub to forest, was the process of the primary land cover change. __________ Translated from Journal of Plant Ecology, 2006, 30(2): 239–251 [译自: 植物生态学报]     

Evaluation of sustainable land management in urban area: A case study of Shanghai,China

With the accelerating urbanization process, there is an increasing shortage of land resource. It leads to an increasingly serious conflicts between built-up areas and other types of land use. This will further hinder city sustainable development. To address the issue, this paper takes urban land management sustainability as the study object and puts forward an evaluation method on sustainable land management (SLM) in urban area. First, four aspects of sustainable land management are proposed, namely economic progress, social stability, urban improvement and ecological balance. Second, a system with fourteen indicators is built according to the aspects. Third, using the indicators, the sub-performance and the overall efficiency of SLM are evaluated with the technique for order preference by similarity to ideal solution (TOPSIS) based on entropy weight. After that, the proposed method is applied to a case study of Shanghai, China. The results show the time series changing of SLM performance from 2000 to 2011 and reveal an unbalanced development path among the four aspects of SLM. Accordingly, policy recommendations are proposed to improve the sustainable land management efficiency. Therefore, it demonstrates that the proposed evaluation method can be used to reveal to what extend the urban land use is reasonable and sustainable and provides guidance on government urban land planning and policy making. Consequently, it helps to improve the land use efficiency and ease the land use conflict.     

长江口不同区段围垦区土地利用/覆被变化的时空动态

基于1987、1995、2000和2006年长江口TM、ETM遥感影像,利用RS、GIS与数学统计方法,对长江口不同围垦区土地利用动态进行了分析.结果表明：研究期间,不同围垦区草地面积所占比例在空间上的差异达显著水平（P＜0.05）,大棚用地和水田面积所占比例在时间序列上的差异达显著水平(P＜0.05);去除围垦时间的因素,不同围垦区土地利用多样性指数的变化无显著性差异;土地利用年变化速率在空间上差异不显著,在时间上具有显著差异的土地类型为大棚用地和建筑用地;不同围垦区的土地利用程度具有一致性,土地利用转移方向的差异也不显著,转移强度相似.长江口不同围垦区的土地利用动态主要受围垦时间的影响.     

Land abandonment as a precursor of built-up development at the sprawling periphery of former socialist cities

In former socialist countries, as cities expanded they permeated into nearby agricultural areas. The periphery then became a mosaic of built-up and agricultural patches. Due to small sizes, inconvenient shapes and scattered locations, the parcels often became unprofitable for agricultural use, and were later abandoned and frequently transformed into built-up areas. Our paper aims to assess whether agricultural land abandonment can be considered a valid precursor of built-up development. The periphery of Bucharest was chosen as the study area, and analyzed over a period of 11 years (2002–2013) based on data sets derived from aerial images. Logistic regression models were used to test whether land abandonment was a significant explanatory variable of built-up development along with other socio-economic, land use, and urban planning variables. The results showed that land abandonment has the potential to be considered a precursor of built-up development. It acts within a cause and effect framework, being influenced by ongoing economic transformations, and changes in urban regulations. Its addition as an explanatory variable in a built-up prediction model significantly increased the prediction power, which makes it a useful variable in urban land use change scenarios. The type of observed abandonment at the periphery of urban areas follows a different pathway compared to land abandonment observed in remote or rural areas. Here, land abandonment is the result of anticipated higher profits through new economic opportunities and urbanization. Monitoring of abandoned land and urban sprawl could enable local authorities to evaluate the outcomes of planning policies and economic incentives.     

南方水土流失严重区的生态脆弱性时空演变

生态环境脆弱性评价研究,对生态环境保护与修复具有重要意义.以福建省长汀县为研究区,选择坡度、土壤类型、多年平均降雨量、地形起伏度、归一化植被指数、人口密度、土地利用类型7个指标,通过多重共线性诊断分析,构建生态脆弱性评价指标体系,采用熵权法及综合指数法对1999、2006和2014年长汀县生态脆弱性进行定量评价,分析生态脆弱性时空分布及变化.结果表明: 1999—2014年,研究区生态脆弱性等级指数总体减小,局部增大.研究区1999、2006和2014年生态脆弱性指数平均值分别为0.4533±0.1216、0.4160±0.1110和0.3916±0.1139,整体处于中等脆弱水平;生态脆弱性等级指数从1999年的2.92下降到2006年的2.38,再下降到2014年的2.13.生态脆弱性的空间格局呈内高外低的分布特征,高脆弱等级区主要分布在坡度<15°、海拔<500 m的河田镇及汀州镇一带.研究期间,生态脆弱性等级指数降幅最大的是三洲乡,最小的是汀州镇.