快速城市化过程中土地覆盖格局研究——以深圳市为例

研究一个以城市化过程为主的土地利用/覆盖变化可以从不同的角度出发。选择景观生态学中的景观格局的研究方法,对快速城市化地区——深圳市的城市化过程中的土地利用/覆盖的动态变化进行研究。具体选择景观格局指数中的破碎度指数、Shannon-Weaver多样性指数和聚集度指数,来表征斑块水平、景观水平、区域水平3个不同层次的土地覆盖格局。首先在区域水平上,分析了深圳全市,以及经济特区和特区外的宝安区、龙岗区的土地覆盖格局变化。在此基础上,以研究区的镇级行政单元为景观单元,计算了镇级行政区域以及镇级行政区海拔0～30m的区域的景观格局指数,在景观水平上分析了区域经济发展水平和速度,以及地形因素对土地覆盖格局变化的影响。随后分析了研究区各土地覆盖类型以及不同时期的斑块水平上的土地覆盖格局。最后以城镇用地比例表征城市化水平,讨论了城市化水平与土地覆盖格局变化的关系。在城市化初期,景观类型多样性和斑块破碎化程度出现上升趋势,空间聚集性下降,生态安全问题开始突现。在城市化水平20%～40%之间,其景观类型多样性和斑块破碎化程度达到较高水平,而空间聚集度水平较低,生态安全水平明显下降;随着城市化过程的不断深入,城市化水平不断提高,景观类型多样性和斑块破碎化程度又出现了较为明     

流域景观结构的城市化影响与生态风险评价

以南京市九乡河流域为研究区域,以2003、2009年两期遥感影像数据为基本信息,在构建生态风险指数的基础上,利用ARCGIS的空间分析功能,揭示了城市化对研究区景观结构的影响,生态风险的时空变化以及城市化与生态风险之间的关系。结果表明：2003-2009年,城市化过程使流域的景观结构发生较大变化,建设用地大幅增加,分离度降低,而耕地则大幅减少,耕地、水域、草地等景观类型的分离度、破碎度增加;流域生态风险程度从中度/低风险向中度/较高风险转变,生态风险有增加的趋势;生态风险的空间差异明显,生态风险较低的区域主要集中在流域南部青龙山一带,较高的区域主要集中在西北部地区,中度风险区集中在流域中部的平原农业区;城市化对生态风险的正效应明显,生态风险随着城市化水平的增加而升高。     

“城-郊-乡”森林生态样带植被变化梯度分析

沿纽约市“市区－郊区－农区”１４０ｋｍ森林生态样带,对９个样地１９个样方的森林植被进行了研究。植被组成和结构沿样带变化明显,分异出城区森林、郊区森林和农区森林等不同类型,优势种替代明显,植物种类也形成了不同的生态类型。植被的梯度变化与人类活动密切相关,城市化对植被有重要影响。森林生态样带是研究人类活动对植被影响的好手段。     

基于生态系统服务的城市化区域生态风险表征方法研究

快速城市化导致城市周边区域生态系统服务损失并引发生态风险。以多种类型的生态系统服务作为生态风险的评价终点,构建了基于服务价值量的城市化区域生态风险表征方法,以北京市为例对方法进行了应用,并进行了风险评价结果的不确定性分析和参数敏感性分析。案例研究显示2015年北京市生态风险总体处于低风险接近中等风险水平,低风险和极低风险区域面积占全市的50%以上,主要分布于北京市西部和北部,高风险和极高风险区域面积占20%左右,主要分布于中心城区。生态风险空间格局特征表明北京市城市区域的扩张造成周边区域生态系统服务的下降,导致生态风险水平的上升。研究提出的生态风险指数同生态系统服务当量因子间具有显著的线性关系,可用于估算生态系统服务价值。不确定性和参数敏感性分析表明生态风险指数计算结果变异较小,指数具有较高的可靠性。研究方法能够综合表征城市化区域的生态风险,定量表征结果便于决策者理解,具有应用于风险评价和管理实践的价值。     

不同生态恢复措施对草地样带食物消费的影响——以锡林郭勒盟为例

生态工程的实施对区域居民生产生活产生了重要影响。以锡林郭勒草地样带为例,利用2017年8月—2018年7月农牧户食物跟踪调查数据、农牧户问卷调查数据、生态恢复措施数据,结合土地利用数据和社会经济数据等,重点分析了不同生态恢复措施对锡林郭勒草地样带农牧户食物消费的影响。研究结果显示:(1)锡林郭勒草地样带生态恢复措施沿样带自北向南实施力度逐渐变弱,草地恢复措施由以草畜平衡、休牧和禁牧为主向休牧和围栏封育为主转变,草地恢复措施中对人类活动的限制也随之由弱变强;(2)沿草地样带自北向南居民食物消费形成了三种模式,在食物消费数量和消费结构上呈显出由牧区特征向农区特征的转变,即人均食物消费量沿样带递减,食物消费由肉蛋奶和蔬菜水果为主向粮食和蔬菜水果为主转变;(3)食物消费模式受到草地供给、收入及其结构、文化习俗和职业分布等生态、经济和社会多方面因素的影响。研究为实现区域生态、经济和社会的协调发展相关政策的制定提供参考。     

城市化对合肥蝶类多样性的影响

2010年3—10月,沿城市发展梯度选取了合肥市3个区域(城市、城郊和农村),进行蝴蝶调查。共采集蝴蝶1484只,隶属7科28属34种。结果表明:研究区域优势种蝶类为菜粉蝶(Pieris rapae)、酢浆灰蝶(Pseudozizeeria maha)、黄钩蛱蝶(Polygonia c-aureum);合肥不同城市化区域蝶类多样性存在差异,其多样性指数变化趋势为农村城郊城市;农村和城郊的多样性指数和丰富度指数在7月最高,城市8月最高;城市和城郊的优势度指数在8月最高,农村7月最高;3种不同城市化区域的均匀度指数均是8月最高。在快速城市化过程中,应根据不同城市化水平、不同生境类型采取不同的措施,保护和促进城市生物多样性。     

港湾快速城市化地区景观生态安全评价——以厦门市为例

以压力-状态-响应(PSR)为概念框架构建厦门景观生态安全评价指标体系,以TM遥感影像为基础数据元,对可空间插值指标进行格网采样空间插值,对不可空间插值指标进行专家赋值,采用RS和GIS相结合的技术,通过空间叠加得到厦门市2003年和2006年的景观生态安全综合指数,以揭示厦门市区域景观生态安全的空间分布规律.研究结果表明:(1) 2003年厦门景观生态安全度平均值为0.586,处于中等安全水平,2006年平均值为0.650,处于中高安全水平,区域景观生态安全度整体水平在小幅度提高;(2) 各行政分区2006年较2003年数值均有所提高,2003年其安全度自高向低排序依次是同安>翔安>思明>海沧=集美>厦门海域>湖里,2006年其安全度自高向低排序依次是同安>思明>海沧=翔安>集美>湖里>厦门海域;(3) 景观变化压力指数2006年较2003年有所提升,但是景观生态安全调控力度也在加大,缓解了城市化过程对区域景观生态安全的压力和影响.     

城市化对区域生态足迹的影响及其耦合关系

城市系统与区域生态系统间存在着复杂的相互影响,分析二者的交互耦合关系,可以客观地反映区域生态协调发展程度,为区域城市化发展提供科学依据。在修正城市生态足迹模型的基础上,计算了2000—2015年昆明市三维生态足迹动态,并建立了城市化综合评价指标体系,探讨生态足迹模型变化的驱动因子,构建城市化与生态耦合模型并测算其协调度。结果表明:过去15年间,昆明市土地利用类型的流转加剧、建设用地比例提升、经济增长和社会进步指标反映出城市化水平逐年提高;自然资源消耗增加和污染排放加剧使得人均生态足迹逐年上升。研究初期,人均生态承载力下降态势明显,后逐渐有所上升,生态赤字逐年减小,资源压力有所减轻。生态足迹广度基本不变、生态足迹深度先上升后下降、资源的利用效率逐年增加,其主要驱动因素在于社会层面的高质量城市化发展与经济产业结构调整。昆明市生态足迹与城市化耦合水平及协调度均呈逐年稳定上升,于2015年基本过渡到协调阶段;生态承载力与城市化耦合水平及协调度均呈波动上升态势,这与城市化负向作用逐渐积累、集中凸显相关。总体上,昆明市城市化进程中,需要提升城市化发展质量,管控城市扩张规模。     

基于梯度分析的重庆市主城区城市扩展的景观生态效应

研究快速城市化地区景观格局变化及景观生态效应,有助于加强城市生态环境规划和土地管理。以重庆市主城区为研究对象,借助于Arc GIS 9.3和Fragstats 4.2软件,采用景观扩展指数、景观人工干扰强度模型、景观格局分析相结合的方法,分别从城市扩展模式、人为干扰强度、景观格局梯度等3个方面对1995—2014年研究区城市扩展过程中景观组分变化引起的生态效应进行综合分析。结果表明:2001年之后研究区受地形地貌及交通的影响,占主导优势的边缘扩展模式随时间变化呈减弱趋势,跳跃扩展模式优势却不断增强,而填充扩展模式始终处于同期最低值;1995—2014年,以林地、草地、水域等为主的低、低中强度景观人工干扰区域变化稳中略有增长,但以城乡居民点和工业用地为主高强度景观人工干扰区域却在2007年和2014年呈现出向中、中高强度区域蔓延的态势,旱地、水田空间丧失严重;南-北向和东-西向样带随着距城区中心越远,斑块密度、平均欧式最近邻体距离、Shannon多样性指数值越高,而靠近城区中心区域上述相关景观指数值随时间变化却呈下降趋势;且聚集度指数在时空上的变化却正好与之相反。在南-北向和东-西向样带局部区域景观格局梯度变化存在显著的时空差异,这对城市化过程中景观组分变化引起的生态效应产生深远的影响。     

快速城市化地区生态质量退降的自组织临界性 ——以深圳市南山区为例

弄清快速城市化地区生态退降过程的机制,可以为相关景观动态模型建设和调控策略选择创造有利条件。借助于自组织临界性理论和方法,在基于多时段遥感影像数据的景观分类和生态质量制图结果支持下,以深圳市南山区为例进行了快速城市化地区生态质量退降的自组织临界性研究,以期揭示城市化过程与生态质量退降过程的响应关系和生态质量退降的过程特点。结果表明,工作区内建设用地扩张过程和生态质量退降过程均具有典型的自组织临界性特点;区域生态质量退降主要是由建设用地扩张导致3种不同生态质量区域之间发生的3种主要生态质量退降过程造成的;建设用地扩张和3种主要生态退降过程的动态分形指数都呈现出不断增加的趋势;具有自组织临界特征的建设用地扩张过程是同样具有白组织临界性特点的各种生态质量退降过程发生和发展的主要驱动力来源。     

城镇化对我国食物消费系统氮素流动及循环利用的影响

城镇化的快速发展,在改变养分氮素流动模式的同时带来了巨大的生态环境压力和严重的污染问题.以1982年、1992年和2002年我国城镇与农村居民食物消费系统氮素流动为对象,采用物质流分析方法,探讨了城镇化对氮素流动特征及循环利用率的影响.结果表明:2002年我国城镇居民人均消费氮量为4.770kg,高于农村居民(4.314kg)10%.1982年到2002年,随着城镇化率的提高,城镇居民消费的食物氮提高了145.3%,农村减少了8.1%;城镇排入水体环境的氮增加了18.4倍,而氮素循环利用率只有13.0%,降低了40个百分点.情景分析结果表明,如果在人口增加的同时,食物结构达到国家营养纲要的标准,到2010年我国植物性氮消费量比2002年将增多142.3万t,增加了37.6%,动物性氮消费量将增多53.8万t,增加了 27.1%,城镇产生的粪尿和垃圾中氮将增加126万t.因此,伴随城镇化快速发展,在带来食物氮素需求和环境排放氮素大幅度增加的同时,也会对动植物生产带来巨大压力.     

Variations in air quality during rapid urbanization in Shanghai,China

Shanghai is the largest commercial and industrial city of China, but air quality issues have hindered its development in becoming a “global city.” This study used monitoring data on SO₂, NO _x , acid rain pH, dustfall, and total suspended particles (TSP) from the Shanghai Environmental Monitoring Center to evaluate and analyze the air quality in urban, suburban, and rural areas during the period 1983–2005. The results showed that the spatial pattern of air parameters was determined by the level of urbanization; thus, the higher the level of urbanization, the worse the air quality. On the whole, the atmospheric environment of the three spatial regions improved gradually because of economical growth and environmental protection since the 1990s. For the entire region of Shanghai, the relationship between the integrated air quality index and gross domestic product (GDP) per capita was an N-shaped environmental Kuznets curve (EKC) due to decreasing air quality in suburban and rural areas this century. Thus, environmental controls should be increased in Shanghai, especially in developing suburban and rural areas during rapid urbanization.     

The heat is on: Genetic adaptation to urbanization mediated by thermal tolerance and body size

Worldwide, urbanization leads to tremendous anthropogenic environmental alterations, causing strong selection pressures on populations of animals and plants. Although a key feature of urban areas is their higher temperature (“urban heat islands”), adaptive thermal evolution in organisms inhabiting urban areas has rarely been studied. We tested for evolution of a higher heat tolerance (CT_MAX) in urban populations of the water flea Daphnia magna, a keystone grazer in freshwater ecosystems, by carrying out a common garden experiment at two temperatures (20°C and 24°C) with genotypes of 13 natural populations ordered along a well‐defined urbanization gradient. We also assessed body size and haemoglobin concentration to identify underlying physiological drivers of responses in CT_MAX. We found a higher CT_MAX in animals isolated from urban compared to rural habitats and in animals reared at higher temperatures. We also observed substantial genetic variation in thermal tolerance within populations. Overall, smaller animals were more heat tolerant. While urban animals mature at smaller size, the effect of urbanization on thermal tolerance is only in part caused by reductions in body size. Although urban Daphnia contained higher concentrations of haemoglobin, this did not contribute to their higher CT_MAX. Our results provide evidence of adaptive thermal evolution to urbanization in the water flea Daphnia. In addition, our results show both evolutionary potential and adaptive plasticity in rural as well as urban Daphnia populations, facilitating responses to warming. Given the important ecological role of Daphnia in ponds and lakes, these adaptive responses likely impact food web dynamics, top‐down control of algae, water quality, and the socio‐economic value of urban ponds.     

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.     

Effects of urbanization on stream benthic invertebrate communities in Central Amazon

Urbanization and its physical and chemical effects on aquatic environments influence invertebrate communities negatively. Yet, it is not clear how urbanization affects inter-annual variation of invertebrate assemblages in streams. We 1) evaluated urbanization effects on the ecological conditions (biotic and abiotic) of streams in Manaus and 2) analyzed invertebrate community variation over time (between 2003 and 2010). Data on abiotic variables and invertebrates from 2003 were obtained from a previous study. In 2010 we sampled abiotic variables and invertebrate communities in the same low-order urban streams sampled in 2003 (n = 40). We recorded high values of total nitrogen, total phosphorous, deforestation, total impervious area (TIA), water temperature, pH, and electrical conductivity in the most urbanized streams, as compared to the least-impacted ones. In contrast, the least-impacted streams had high dissolved oxygen concentrations. Water quality was poorer in 2010 than in 2003: oxygen concentration was lower and total nitrogen, total phosphorous, deforestation, and TIA significantly higher in 2010. We recorded higher inter-annual variation of abiotic variables in the most-impacted streams as compared to the least-impacted streams. EPT (%, Ephemeroptera, Plecoptera, and Trichoptera) and richness metrics decreased with urbanization. On the other hand, % OP (percent of Oligochaeta and Psychodidae) increased with urbanization. Observed and EPT richness and% OP increased between 2003 and 2010. On the other hand, rarefied richness decreased between years. Increases of observed and EPT richness between 2003 and 2010 were related to low inter-annual variability in streams conditions; however, differences of% OP and rarefied richness were not related to inter-annual variability in environmental conditions. The degree of urbanization did not explain the magnitude of the within-stream difference of invertebrate communities between 2003 and 2010. The increased effects of urbanization represented by the abiotic variables sampled and the reduction of invertebrate richness and increased dominance of tolerant taxa indicate that public policy is not enough to protect or mitigate human impacts on the urban water systems under study.     

Response of vegetation phenology to urbanization in the conterminous United States

The influence of urbanization on vegetation phenology is gaining considerable attention due to its implications for human health, cycling of carbon and other nutrients in Earth system. In this study, we examined the relationship between change in vegetation phenology and urban size, an indicator of urbanization, for the conterminous United States. We studied more than 4500 urban clusters of varying size to determine the impact of urbanization on plant phenology, with the aids of remotely sensed observations since 2003–2012. We found that phenology cycle (changes in vegetation greenness) in urban areas starts earlier (start of season, SOS) and ends later (end of season, EOS), resulting in a longer growing season length (GSL), when compared to the respective surrounding urban areas. The average difference of GSL between urban and rural areas over all vegetation types, considered in this study, is about 9 days. Also, the extended GSL in urban area is consistent among different climate zones in the United States, whereas their magnitudes are varying across regions. We found that a tenfold increase in urban size could result in an earlier SOS of about 1.3 days and a later EOS of around 2.4 days. As a result, the GSL could be extended by approximately 3.6 days with a range of 1.6–6.5 days for 25th ~ 75th quantiles, with a median value of about 2.1 days. For different vegetation types, the phenology response to urbanization, as defined by GSL, ranges from 1 to 4 days. The quantitative relationship between phenology and urbanization is of great use for developing improved models of vegetation phenology dynamics under future urbanization, and for developing change indicators to assess the impacts of urbanization on vegetation phenology.     

城镇化对我国食物消费系统氮素水体排放的影响

城镇化的快速发展,将带来巨大的生态环境压力和严重的污染问题.以1982年、1992年和2002年我国城镇与农村居民食用氮的流动去向为对象,探讨了城镇化对氮素水体排放的影响.结果表明:城镇居民食用氮与排泄的粪尿氮高于农村居民;人均排入水体氮量,1982年城镇与农村居民大体相当,1992年、2002年城镇居民是农村居民2.8倍;粪尿氮排入水体比率,1982年城镇与农村基本相当,在7.5%左右,但到2002年城镇粪尿氮排入水体比率高达56.7%,城镇比农村要高34个百分点.情景分析结果表明,如果在人口增加的同时还要改善食物结构增加蛋白质摄入量, 2020年粪尿氮总产生量将增加121～155万t,排入水体氮量也将增加41～64万t.提高粪尿还田率、污水处理率及氮的去除率可以降低粪尿氮排入水体比率.     

Spatio-temporal assessment of urbanization impacts on ecosystem services: Case study of Nanjing City,China

Rapid urbanization is a global phenomenon that has altered many ecosystems, causing a decline in many ecosystem services, generating ecological risks such as water shortages, air pollution, and soil pollution. Here, we present a conceptual framework quantifying how urbanization influences the ecosystem services in a typical city (Nanjing) of China. Between 2000 and 2010, we separated the city into three urbanization categories (developing urban, developed urban, and rural areas) and quantified the status of six critical ecosystem services (food supply, carbon sequestration, soil water storage, air pollution removal, habitat suitability, and recreation potential). Our results show that urbanization significantly impacted all ecosystem services, with detected changes in ecosystem services being spatially heterogeneous due to urban expansion and population mobility. Developed areas contained greater amounts of green infrastructure, which improved carbon storage and reduced air pollution. In contrast, the rapid expansion of urban and industrial land in developing urban areas led to lower food supply, carbon sequestration, soil water storage, and habitat suitability. The expansion of rural residential areas led to lower soil water storage, carbon sequestration, and food supply, while greater amounts of abandoned cropland resulted in increased carbon sequestration, but decreased food supply in rural areas. Analysis of the interactions between pairs of ecosystem services identified urbanization development problems, including abandoned cropland and the expansion of rural residential land. Lastly, we proposed four key urban planning measures to mitigate the loss of ecosystem services during rapid urbanization. Acquiring quantitative knowledge about how rapid urbanization drives changes to ecosystem changes may help guide sustainable urban planning with respect to ecosystem service use, urban development, and human welfare benefits.     

成渝城市群城镇化与生态环境耦合协调及交互影响

以成都-重庆(简称成渝)城市群为研究对象,从经济、社会、生态和城乡协调4个子系统构建城镇化综合评价指标体系,将生态环境承载力和生态弹性结合构建生态环境综合评价指标体系,应用耦合协调度模型测度2005—2018年成渝城市群各地级市城镇化与生态环境的耦合协调度,借助GIS空间分析法、象限分析法和Tapio模型,分析成渝城市群各地级市城镇化与生态环境交互作用的类型、演化路径及其解耦路径。结果表明: 研究期间,成渝城市群的城镇化质量呈现波动上升趋势,以成都、重庆为高值区呈“双核”向四周辐射;生态环境质量缓慢提升,呈四周高、中部低,开口向北的“U”型空间格局。城镇化系统和生态环境系统耦合协调水平较高,总体呈上升的趋势,协调类型由以濒临失调和勉强协调为主逐渐向以中度协调为主演变,呈现中部低、东西高的空间格局。城镇化与生态环境交互作用的演化路径呈现稳定型和变化型2个大类。稳定型包括5个亚类20个城市,成都、德阳、绵阳等城市始终是良好协调型;变化型包括9个亚类16个城市,重庆主城区、铜梁等多数城市的协调度提升,呈“上升式”发展;合川、自贡等少数城市呈“下沉式”发展。生态环境增长率和城镇化增长率均为正,城镇化与生态环境的解耦路径以弱脱钩和扩张连接为主。     

城市化对土壤生态环境的影响研究进展

城市土壤是城市生态系统中最重要的组成部分之一,发挥着重要的生态系统服务功能。在全球快速城市化的背景下,城市土壤受到人类活动的强烈干扰,土壤物理、化学性质发生改变,土壤退化与污染日益加重。城市土壤退化导致土壤动物生态特征与行为模式发生变化,城市景观格局与土地利用类型的变化强烈影响了土壤动物的栖息地,为土壤动物的生存与生物多样性带来潜在威胁;另一方面,城市化过程改变了土壤微生物群落组成与功能特征。城市化直接影响了城市土壤维持植物生长、土壤自然消减能力以及碳储存功能等重要的生态系统服务功能。针对城市化过程对土壤生态环境产生的一系列影响,需要采用科学的管理方式,改善土壤理化性质,提高土壤环境质量,保护和恢复土壤生物多样性,从而增强城市土壤的生态系统服务功能。