基于遥感和GIS的城乡交错带景观演变研究——以上海西南地区为例

On landscape dynamics of the urban-rural ecotone based on remote sensing and GIS: a case study of southwest Shanghai

以上海西南城乡交错带 1 984、1 989和 1 994年 3个时相的航空遥感图像为主要信息源 ,在 ARCIIN-FO地理信息系统软件的支持下 ,建立上海西南城乡交错带景观数据库。将城乡交错带划分出 5个一级景观类型 ,1 2个二级景观类型。运用景观格局分析指数对 1 984～ 1 994年上海西南城乡交错带的景观格局特征及其动态进行研究。通过分析 ,可以看到 1 984～ 1 989年和 1 989～ 1 994年两个时期各种景观的结构变化特征都有明显的差异。城乡交错带作为城市化发展的一个过程 ,区域发展常常受政策性因素的作用较大 ,不合理的景观格局常常是城市生态问题产生的症结所在。虽然景观类型个体受人为控制较强 ,但整体却由于缺乏协调而导致一定程度的无序性 ,这将造成今后景观结构调整和生态建设的难点。因此今后有必要确立城乡交错带在城市发展中的地位和作用 ,建立合理的景观结构 ,注重保护开敞空间 ,确立城市自然生态系统发展体系 ,提高区域生态功能。

The urban-rural ecotone is an area which is strongly influenced by the urbaniza tion process. Its spatial uncertainty and temporal quality tends to cause undesi rable landscape patterns, and has been an axial point of the problems of urban e cology.The study of landscape patterns and dynamics within the urban-rural ecot one with remote sensing and GIS is useful in determining the spatial features of the ecotone and the succession of landscape factors as indicators of the relati onship between urbanization and ecological process.The study area was situated i n southwest Shanghai, and was 94.56km2. All the data came from the color and i nfrared aerial photos of Shanghai, which included photos of 1984(1∶10,000), pho tos of 1989(1∶60,000) and photos of 1994(1∶32,000).The study area was typical in terms of urban spatial expansion of Shanghai, because it was integrated into the urban area with the expansion of Shanghai after the 1980's. This study area was divided into 5 primary landscape types and 12 secondary landscape types. The analysis indices of landscape pattern included “Proportion of Patch Area”, “ Patch Density”, “Patch Size”, “Diversity Index”, “Evenness Index”, “Frag mentation Index”, “Fractal Dimension Index”, and “Medial Nearest Neighbor In dex”. With the rapid economic development of Shanghai during the ten years between 198 4 and 1994, landuse fragmentation due to factory warehouse development increased continuously, which embodied intensive development of a landscape in the latter stages of urbanization. The nearest neighbor index of warehouse patch increased , and the distribution tended to be regular, becoming the preponderant landscape in the urban-rural ecotone. A significant increase in urban population and development occurred between 1989 and 1994. The rapid increase was influenced by the opening of the Pudong area, and signified a rapid stage of growth. Urban development appeared in a pattern represented by low-density, widespread distribution, and grew most aggressively along the quickly growing roadway syste m which was of a reasonably high quality. This phenomenon indicated growth patte rns were driven by urban centripetal force and traffic, with development tendenc ies that tended to predictably follow the location of those systems. During these ten years of the case study, the area ratio and the fragmentation d egree of open fields, vegetable fields, water area and the rural population land scape gradually decreased, and tended to be dispersed. Although vegetable fields were maintained on a relatively large scale, the density reduced, becoming an i ntensively developed landscape.The annual reduced areas of open field and vegeta ble field were in contradiction to the regulation of “the General Planning of Land Utilization in Shanghai Cou nty”, which showed that the development of urban-rural area was influenced by local political factors to a large extent; and that the official plan was not re sponsive to the reality of development. This contributed to the spatial uncertai nty of the urban-rural ecotone. In contrast to the large reduction of open fiel d s and vegetable fields, the increase of public green space in the city was limit ed, and couldn't compensate for the disappearance of semi-natural landscape of field and vegetable land. Due to the patch size of public green space; its centralized distribution, and t he nearest neighbor of patch all adversely impacted the function of ecological s ystem. In the urban-rural ecotone, water areas of semi-natural landscape were faced with reduction of area and number, and increase of the number of patches a nd fragmentation. Until 1994, open water and wet areas were the landscape patter n which appeared most frequently. Since that time, the fractal dimension index c ontinuously decreased, patch shape simplified, and the regional ecological modif ying function weakened. Water areas comprised the most complex shapes of landsca pe types, and had the most mutual borders with other landscape patches. So water