城市绿色空间格局的定量化方法研究进展

Research progress in the quantitative methods of urban green space patterns

城市绿色空间格局的变化是影响城市生态系统社会、经济与生态功能的重要因素。在分析城市绿地数量和结构时空动态变化的基础上,重点综述了城市绿地斑块和廊道连接的景观格局指数法和网络分析方法,探讨了城市绿地与居住用地的空间交互作用以及可达性分析方法,比较了城市绿地沿城乡分布的梯度分析方法。并总结了城市绿色空间格局研究的热点领域,包括城市绿色空间格局的空间显式表征和多尺度分析,以及格局的定量研究与规划的结合,并应用于生态系统服务的评价。

The concept of urban green space, which comprises gardens and parks, urban forestry, urban agriculture, greenways, waterfront greenbelt, and roof greening, is different from traditional garden greenland, and forms functional econetworks. On the other hand, the ecological and environmental impacts of urbanization extend over large areas even though the areal percentage of urban land in regional land-cover maps is typically quite small. Urban land use changes altered the green space patterns dramatically, and sequentially influenced urban landscape structure and ecosystem services. With the concern of high speed of urbanization and serious urban environmental problems, a common consensus has been achieved that the spatio-temporal dynamics of urban green space patterns are important factors to social, economic and ecological functions of urban ecosystems. Many countries have formulated urban landscaping as an essential part of the strategy of sustainable development. Nevertheless, under most circumstances, the green spaces were built more arbitrarily than based upon scientific analyses. Therefore, study on the quantitative methods of urban green space patterns revealed broad applications in protecting and planning green space structure and functions, which could further promote urban human settlements. Among various quantitative methods of urban green space patterns, detecting methods of green space changes under urbanization was a hotspot. Urban development and suburbanization had shrunk the size of green spaces and got the green patches fragmented. In terms of measuring green space fragmentation, it was of prime importance to select appropriate fragmentation metrics and improve the method of weighting to aggregate to get an unique fragmentation score. Contrary to landscape fragmentation, improvement in green space connectivity rehabilitated and optimized network structure, which could further enhance ecosystem services supply. Recently, assessment of green space connectivity had been transited from metric-based approaches to the coupling of both landscape metrics and models, and an increasing number of researches focused on the network scenario analysis of urban green spaces had gradually formed an united methodological framework for reconstruction of urban eco-networks. Meanwhile, accessibility analysis of urban green spaces was an important researching topic to assess the spatial interactions between residential land use and urban green spaces, and could help to identify the truly underserved areas lacking opportunities of accessing green spaces which was critical for effective urban planning and development. Moreover, spatial-temporal gradient analysis, combined with quantified landscape metrics, was judged to be the most appropriate way of relating the spatial pattern of urban green spaces to urbanization and underlying human processes, and of determining their influence on ecological attributes of the environment. Three sampling methods were commonly used for detecting the gradient changes of green space patterns ： buffer gradient analysis, directional transects and moving window method. For comparative studies on the spatial variations of green space patterns along urban-rural gradients, multiple approaches of mapping peri-urban areas should be addressed in a scientific way. In the final section, suggestions for future researches were put forward, which highlighted the importance of quantifying green space patterns spatially explicit at multiple scales. In order to achieve these goals, the so-called local analysis, combined with quantified landscape metrics and accessibility measurements, which was often conducted at grid level, patch level and local areas according to the research objectives respectively, was widely used. Considering the scale effects involved in the spatial analysis associated with urbanization, multi-scale methods of quantifying green space patterns need to be carried out both at diverse spatial grains and extents to facilitate comparisons among different cities and periods of time. In addition, the quantification of green space patterns should also be integrated with planning or policy issues, as well as be applied to evaluating ecosystem services. In other words, quantifying green space patterns could not only serve as guidelines in terms of decision making, but help evaluating the impacts of regional development policies on future ecological benefits and ecosystem services.