基于GIS的城市绿地景观空间结构研究——以宁波市为例

GIS-based study on spatial structure of urban greenbelt landscapes: Taking Ningbo City as an example

城市绿地景观的空间结构分析是城市景观生态系统研究的重要内容和基本特色之一。分析了城市绿地景观生态系统的空间结构元素及其特征 ,运用景观生态学的原理 ,在 GIS支持下对宁波市城市绿地景观缀块的等级与分布、空间结构的度量进行了研究和分析 ,并对该市的城市绿地景观按行政单元进行了综合评价。研究结果表明 ,宁波市城市绿地缀块个数以面积小于 5 0 0 m2 的小型缀块为主 (95 .3 2 % ) ,而缀块面积大于 3 0 0 0 m2 的大中型和大型缀块虽然个数较少 (仅 0 .75 % ) ,却是构成该市城市绿地景观的主体 (面积占3 5 .99% )。宁波市城市绿地景观多样性指数为 0 .71 7,均匀度为 0 .6 2 9,景观优势度为 0 .6 6 9,聚集度为0 .870 ,破碎度为 0 .2 92 ,总分离度为 1 .45 6 ,绿地廊道密度为 2 .2 3 7,分维数为 1 .3 73。城市绿地景观总体表现为类型分布不均 ,各种类型相差较大 ,破碎度较小 ,多样性程度不高。综合评价结果为江东区最佳 ,景观结构最为合理 ,海曙区次之 ,江北区较差 ,全市总体上较好。研究结果为宁波市城市绿地景观生态系统的规划、设计提供了生态学依据 ,为“生态园林城市”

Urban greenbelt landscapes, including park, street, road, and courtyard greenbelts, are an important component of urban ecosystems. The study of urban greenbelt landscapes is essential for quantifying and improving the quality a city's environment. In this paper, based on the spatial characteristics of urban greenbelt landscape, an index system and content were put forward for urban greenbelt landscape evaluation. The classification and distribution of urban greenbelt landscape patches, and their spatial characteristics, in Ningbo City were examined based on GIS and the theory of landscape ecology. Finally, a comprehensive evaluation was conducted for the urban greenbelt landscapes for each of the administrative areas of Ningbo City. ;The results indicate: (1) the urban greenbelt landscape is an important component of an urban ecosystem. An urban greenbelt landscape can consist of four structural elements: patch, corridor, matrix and edge. Urban greenbelt landscapes are characterized by fragmentation, instability, gradient, and patchiness. They are fragmented by other urban landscape structure associated with traffic and energy infrastructure, unstable due to changes from old city rebuilding and new city expansion, characterized by a gradient of increasing green cover from city center to outskirt, and patchy in structure. (2) In urban ecosystems, large patches may be more important in ecological function than small patches. Small patches supplement the large ones in function. Urban greenbelt patches were divided into four size groups: small patches (<500m 2 in area), medium (500~3000m 2), medium-large size patches (3000~10000m 2) and large size patches (>10000m 2). Small and medium size patches covered 28^40% and 35^61% of the areas in the urban greenbelt landscape, respectively. They were affinitive to the inhabitation in the city and consisted of domestic greenbelt, street greenbelt in residential areas and along roads. The medium-large and large patches constituted 0^75% of the patches but 1/3 of the urban greenbelt landscape. They mostly belonged to public greenbelt park, zoo, hotel, enterprise, and institutions. (3) The landscape diversity was 0^717 (maximum diversity=1^386). The diversity of Jiangdong and Haishu district (0^907 and 0^816) was higher than Jiangbei district (0^295) and the dominance of Jiangbei district was the highest among the three administrative areas, which indicates one kind of greenbelt type was preponderant in this district, and the greenbelt types of Jiangdong and Haishu district was comparatively proportional. The evenness for the city was low (0^629), which indicated the landscape types were not even in abundance and the whole ecosystem was controlled by the few greenbelt landscape types. The landscape fragmentation was 0^292 for the city as a whole. It was 0^383 and 0^652 in Jiangdong and Haishu district where the building speed was high. The fragmentation in Jiangbei district was small because its speed of city building is slower than the other districts. The total isolation in Jiangbei district was the highest in the city (2^636), indicating that greenbelts were relatively concentrated; it was smaller in Jiangdong and Haishu districts (1^209 and 0^778). The greenbelt line corridor density was 2^237km/km 2 in Ningbo City. The greenbelt line corridor density in Haishu district was greater than those in Jiangdong and Jiangbei districts, as the road density in old urban areas was greater than those in new urban areas. The fractal dimension was small for the city as a whole (1^373), indicating the planning principle for city development and building was linier. (4) Fuzzy comprehensive assessment method was used to evaluate greenbelt landscape with indices of urban greenbelt landscape structure and green overlay; the results indicates that the spatial structure of the greenbelt landscape in Ningbo City was good, and the greenbelt landscape in Jiangdong district has the most desirable and that in the Jiangbei district has the least desirable structure. (5) The urban greenbelt landscape no