城市生态系统的格局和过程

城市生态系统是人类活动影响下的复合生态系统。人为的开发利用活动和局地的生物物理条件形成了城市特有的景观格局。城市发展改变了自然的生物栖息环境,从根本上改变了生态系统的结构、过程、功能,以及所提供的各种服务。这种改变最终又会影响人类自身的健康生存。文章综述了国内外有关城市景观格局和和重要生态过程之间相互作用机制的研究进展。通过研究发现,在大尺度上,净初级生产力是衡量城市发展对区域物流、能流影响的有效指标;在小尺度上,城市物流、能流过程和城市内部的景观结构、格局有很强的相关性。城市发展显著的改变了自然的栖息地及生物生长过程,本地植被种类减少,外来种增加,外来种的数量和人口数量有显著的相关性;而城市动物群落主要由一些小型哺乳动物、无脊椎动物、鸟类、两栖爬行类动物组成,其中,鸟类是研究城市化过程的有效指示物种。城市生态系统特有的景观格局及生态等过程显著的改了局部区域的微气候和水文过程,城市气温增加,风速降低,云、雾量增加,地表径流增加,流速加大,污染负荷增强等。因此,控制人类活动,优化土地利用的结构和空间格局,是改善城市生态系统结构和过程,保证可持续发展的基本出发点。但是,目前有关城市-格局-过程之间的影响机制还不十分清楚,尤其是定量研究较少。因此,结合传统的城市生态学,景观生态学的理论和其他相关学科领域的发展,为深入分析城市格局-过程之间的关系提供了重要的研究前景。

Urban landscape pattern and ecological process

Urban system is the complex ecosystem dominated by human being. Various human activities and specific physical conditions shape urban specific landscape. Thus, urban development extremely changes the structure, process and functions of original nature ecosystem. These changes finally would affect human development. Therefore, this article reviewed related researches on urban structure-pattern-process. The analyses showed that on large scale, the net primary productivity (NPP) was the key indicator to measure the impacts of urban development on regional material and energy flow. Relatively, on small scale, within urban area, the material flow and energy flow had strong relations of urban landscape pattern. Urban development significantly changed natural habitats and biological processes. For urban vegetation, native species decreased while the exotic species increased. The amount of exotic species obviously related with urban population. For animals, urban areas mainly accommodated some small mammal, invertebrate, birds and amphiphyte. Among them, birds were the important indicators to monitor urban development. Moreover, urban development changed local microclimate, such as the increase of urban temperature, clouds and mist, the decrease of wind, the increase of surface runoff, speed and pollution load. As a conclusion, to control human activities, optimizes landscape structure and pattern is the key essential to sustain urban development. However, not many researches focus on urban landscape struc-ture-pattern-process, especially quantitative analyses. In the future, to integrate traditional ecology, landscape ecology and advanced technologies provides remarkable potentials for pursuing urban structure-pattern-process.