天津市“城-郊-乡”样带土壤种子库特征分析

为了解天津市不同地理位置土壤种子库物种组成和群落结构的变化,沿天津市设置＂城区—城郊—远郊＂的生态样带,在6个典型样地选取20个样方进行土壤种子库的采样工作并进行萌发试验。结果表明：土壤种子库的密度、物种组成及群落结构差异性明显,除趋势对应分析后分异出典型的城市土壤种子库、城郊土壤种子库、远郊土壤种子库3种类型。从远郊到城区,土壤种子库的密度递增,相似性指数也递增,而物种丰富度却递减。相比远郊地区,城区、城郊区土壤种子库物种丰富度损失率分别为66.67%、45.23%。城区因城市化水平较高及频繁的人为干扰致使土壤种子库物种呈现匀质化特点,物种多为一年生的耐踩踏草本。城郊区的多样性指数、生态优势度指数、均匀度指数最低,但是种子库密度较大,物种丰富,萌发种子中木本植物可观,适合用于进行植被恢复的试验研究。     

基于土地转移矩阵的生态服务功能研究——以南京市仙林新市区为例

以南京市仙林新市区为例,运用土地转移矩阵方法分析土地利用变化,并采用专家打分法和层次分析法对生态服务功能进行分类评价,对其结果进行空间化表达,分析土地利用变化对生态服务功能的影响。结果表明:(1)2003—2013年仙林新市区耕地和水体面积大量减少,而建设用地、密集型草地和裸地面积大量增加。土地利用类型变化主要体现在耕地、水体向建设用地、密集型草地和裸地的转移。(2)区域生态服务功能整体降低,但生态服务功能改变程度具有空间异质性,西北部和中部的大部分区域生态服务功能降低程度高,而东南部小部分区域降低程度低。(3)耕地、有林地和水体向建设用地的转移是造成生态服务功能降低的主要原因,其作用程度达到70%以上。     

基于供需构造的北京水循环动态失衡及修复机理

水资源短缺严重制约着北京21世纪世界城市宏伟目标的实现.在引入基于自然与人然良性互动基础上的成水构造、蓄水构造与用水构造等跨学科概念之后,提出区域水生态“供需构造链条说”.进一步,本研究对半个世纪来北京水循环数据分析发现,水资源总量随降水量而变化,相对多年平均量均减,北京水资源生态系统呈弱化态势;2001~2012年用水总量超过水资源总量,水生态系统失衡.循上述发现,对北京区域水生态系统供需数据进行回归分析、揭示北京气候变化与人然活动水文关联效应,指出水循环动态失衡机理的行为贡献因子.最后,基于用水增长有行为上改进空间的思想,提出北京水循环动态失衡在短期运用行为矫正机制,采用总量管理和水市场调节合理用水,长期上运用水环境动态均衡修复原理,启动北京和周边地区的地下水位复升工程的政策建议.     

基于扎根理论的杭州市梅家坞旅游城市化特征与机制

论文选取杭州市梅家坞村为案例地,通过5次实地调研和访谈获取研究资料,运用扎根理论构建了城市近郊地区旅游城市化特征和发生机制模型。研究表明：梅家坞村旅游城市化过程特征和发生机制可抽象成土地利用变化等11个范畴及31个概念;在旅游发展驱动下,多重要素实现了综合动态变化,在不改变乡村风貌、城乡和谐的条件下,推动了新型城市化进程。论文提出并分析了旅游城市化过程特征和发生机制理论模型,认为“梅家坞现象”是旅游城市化的积极例证,是管窥中国“田园城市”的发展方向与路径。     

乡村在城镇化过程中受到的冲击及其发展问题

中国是一个农业历史悠久的大国,乡村在社会中具有重要地位。通过近30多年的改革开放,乡村的建设和农业生产水平均有了显著的提高。但是在工业化、城镇化的浪潮下,乡村所受到的冲击十分剧烈。城镇化是经济与社会发展的强大动力,也是历史发展的必然趋势。城镇化进程有其客观规律,而且城市与乡村之间有着密切联系。因此,人为地阻挡城镇化不利于经济发展。然而,若不顾实际条件,不惜代价地加快城镇化进程,不仅难以保持和提高城市的经济发展和生活质量,而且对乡村的影响会更大。本文在论述中国1949年以来几个阶段城镇化特点的基础上,从近年来城乡差距与乡村人口劳动力的变化、土地高速非农化与粮食安全、乡村生态环境、乡村文化四个方面论述快速城镇化对乡村的冲击,并在此基础上讨论乡村的发展问题。根据上述乡村发展问题,本文提出若干意见,其中最要顾及的是新型城镇化进程中的乡村建设和农业生产。由于我国的自然条件、资源禀赋、各地的经济区位差异很大、发展的起点不同、进程有快慢、水平有高低,所以,以人为本的新型城镇化,特别要在城乡发展一体化的进程中,构建平等协调的城乡关系。各地城镇化的发展时序可有所不同,但必须因地制宜、同时做好乡村发展规划,力求农业现代化与工业化、信息化、城镇化同步,从而使农业和乡村经济得到持续发展。     

Urban sprawl into Natura 2000 network over Europe

Urban growth is a major threat to biodiversity conservation at the global scale. Its impacts are expected to be especially detrimental when it sprawls into the landscape and reaches sites of high conservation value due to the species and ecosystems they host, such as protected areas. I analyzed the degree of urbanization (i.e., urban cover and growth rate) from 2006 to 2015 in protected sites in the Natura 2000 network, which, according to the Habitats and Birds Directives, harbor species and habitats of high conservation concern in Europe. I used data on the degree of land imperviousness from COPERNICUS to calculate and compare urban covers and growth rates inside and outside Natura 2000. I also analyzed the relationships of urban cover and growth rates with a set of characteristics of Natura sites. Urban cover inside Natura 2000 was 10 times lower than outside (0.4% vs. 4%) throughout the European Union. However, the rates of urban growth were slightly higher inside than outside Natura 2000 (4.8% vs. 3.9%), which indicates an incipient urban sprawl inside the network. In general, Natura sites affected most by urbanization were those surrounded by densely populated areas (i.e., urban clusters) that had a low number of species or habitats of conservation concern, albeit some member states had high urban cover or growth rate or both in protected sites with a large number of species or habitats of high conservation value. Small Natura sites had more urban cover than large sites, but urban growth rates were highest in large Natura sites. Natura 2000 is protected against urbanization to some extent, but there is room for improvement. Member states must enact stricter legal protection and control law enforcement to halt urban sprawl into protected areas under the greatest pressure from urban sprawl (i.e., close to urban clusters). Such actions are particularly needed in Natura sites with high urban cover and growth rates and areas where urbanization is affecting small Natura sites of high conservation value, which are especially vulnerable and concentrated in the Mediterranean region.     

生态经济区城市化与生态环境整合动态评价--以雅安市为例

在对雅安市实例评价中,综合考虑了城市化质量、环境和生态3个子系统,最终选取了42个要素指标,建立了3级城市化与生态环境整合评价指标体系;将灰色关联度分析法用于整合动态评价,用层次分析法确定各级指标权重。在参考国家标准值和国内良好特色城市现状值的基础上,结合雅安实际,构造了各项对应指标的目标序列,将其作为该市2007年目标值,计算得到各子系统分指数和整合指数,对其变化趋势和关联性进行了评价分析,发现雅安市正处于强生态弱城市化的勉强协调发展阶段。     

长春市农村城镇化的动力机制

改革开放以来,随着长春市农村城镇化水平的不断提高,农村城镇化快速推进成为该市农村区域的一个重要特征,农村城镇化的动力机制不断地趋于多元化.在这种背景下,从城乡互动、区域非均衡发展的地理学思维,利用城市地理学、区域经济学、城市与区域规划的理论和方法为基础,重点探讨长春市农村城镇化的动力机制问题.     

URBAN IMPACTS ON PHYSICAL STREAM CONDITION: EFFECTS OF SPATIAL SCALE,CONNECTIVITY, AND LONGITUDINAL TRENDS1

ABSTRACT: An assessment of physical conditions in urban streams of the Puget Sound region, coupled with spatially explicit watershed characterizations, demonstrates the importance of spatial scale, drainage network connectivity, and longitudinal downstream trends when considering the effects of urbanization on streams. A rapid stream assessment technique and a multimetric index were used to describe the physical conditions of multiple reaches in four watersheds. Watersheds were characterized using geographic information system (GIS) derived landscape metrics that represent the magnitude of urbanization at three spatial scales and the connectivity of urban land. Physical conditions, as measured by the physical stream conditions index (PSCI), were best explained for the watersheds by two landscape metrics: quantity of intense and grassy urban land in the subwatershed and quantity of intense and grassy urban land within 500 m of the site (R²= 0.52, p > 0.0005). A multiple regression of PSCI with these metrics and an additional connectivity metric (proximity of a road crossing) provided the best model for the three urban watersheds (R²= 0.41, p > 0.0005). Analyses of longitudinal trends in PSCI within the three urban watersheds showed that conditions improved when a stream flowed through an intact riparian buffer with forest or wetland vegetation and without road crossings. Results demonstrate that information on spatial scale and patterns of urbanization is essential to understanding and successfully managing urban streams.     

USING A DISTRIBUTED ROUTING RAINFALL-RUNOFF MODEL1

ABSTRACT: Urban storm water data from four catchments near Miami, Florida, were collected and compiled by the U.S. Geological Survey and were used for testing the applicability of deterministic modeling for characterizing storm water flows from small land use areas. The four sites were:

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