城市景观的类型及其环境生态效能的评价

城市的生态环境质量问题主要是由城市的景观格局变化或用地结构调整所造成的．在城市的自然景观用地中，绿地和水域是两种对城市生态环境具有重要调节作用的景观生态类型．景观生态用地在城市中的分布格局、平面形态及生态体的垂向伸展等状况，都对其生态效能的发挥深具影响．因此，提出用分布指标、形态指标和体量指标3项指标体系来全面真实地刻画生态源地的生态效能，为科学地评价和比较城市的生态环境质量水平提供依据．

TYPES OF URBAN LANDSCAPE AND THE EVALUATION INDEXES ON THEIR ECOLOGICAL EFFICIENCY

In the evaluation of urban environmental quality, there are two types of appraisal systems which must be distinguished: substantial environment quality and state environmental quality, or pollution environment quality and ecological environment quality. These two kinds of qualities are of different properties and their variations have different causes. The problem of pollution environment quality is mainly caused by pollutions from industry, traffic and human lives, whereas the problem of ecological environment quality is mainly bred by the variation of landscape patterns or the adjustment of land use structure. Among the urban nature landscapes, green land and water are the most important ecological regulative lands which have distinct effect on the urban ecological environment. However, as a common ignorance to the eco-effect of urban water, no enough conservation has been given to them. Thus it leads to a quick decreasing of urban water areas. As for the urban green land, the evaluation standards have been limited to such indexes as percentage of green coverage, green land per person, which have obvious defects. In fact, the distributing pattern, the planar shape of ecological lands and the vertical stretch of ecological body, all profoundly affect the exertion of their eco-effects. As a result, the authors put forward such three indexes as distribution index, shape index and capacity index, to describe the eco-effect of ecological land fully and really. We hope that could provide scientific bases for the evaluation and comparison of urban ecological environment.