Li Yan, Zhao Shuqing, Zhao Kun, Xie Ping, Fang Jingyun
Department of Ecology, College of Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, China.
Environ Monit Assess. 2006 Apr;115(1-3):349-59. doi: 10.1007/s10661-006-6559-z. Epub 2006 Apr 13.
Urbanization can exert a profound influence on land covers and landscape characteristics. In this study, we characterize the impact of urbanization on land cover and lacustrine landscape and their consequences in a large urban lake watershed, Donghu Lake watershed (the largest urban lake in China), Central China, by using Landsat TM satellite images of three periods of 1987, 1993 and 1999 and ground-based information. We grouped the land covers into six categories: water body, vegetable land, forested land, shrub-grass land, open area and urban land, and calculated patch-related landscape indices to analyze the effects of urbanization on landscape features. We overlaid the land cover maps of the three periods to track the land cover change processes. The results indicated that urban land continuously expanded from 9.1% of the total watershed area in 1987, to 19.4% in 1993, and to 29.6% in 1999. The vegetable land increased from 7.0% in 1987, 11.9% in 1993, to 13.9% in 1999 to sustain the demands of vegetable for increased urban population. Concurrently, continuous reduction of other land cover types occurred between 1987 and 1999: water body decreased from 30.4% to 23.8%, and forested land from 33.6% to 24.3%. We found that the expansion of urban land has at least in part caused a decrease in relatively wild habitats, such as urban forest and lake water area. These alterations had resulted in significant negative environmental consequences, including decline of lakes, deterioration of water and air quality, and loss of biodiversity.
城市化会对土地覆盖和景观特征产生深远影响。在本研究中，我们利用1987年、1993年和1999年三个时期的陆地卫星专题制图仪（Landsat TM）卫星图像以及地面信息，来描述城市化对中国中部大型城市湖泊流域——东湖流域（中国最大的城市湖泊）的土地覆盖和湖泊景观的影响及其后果。我们将土地覆盖分为六类：水体、菜地、林地、灌草地、空地和城市用地，并计算与斑块相关的景观指数，以分析城市化对景观特征的影响。我们叠加这三个时期的土地覆盖图，来追踪土地覆盖变化过程。结果表明，城市用地持续扩张，从1987年占流域总面积的9.1%，增长到1993年的19.4%，再到1999年的29.6%。菜地从1987年的7.0%增加到1993年的11.9%，再到1999年的13.9%，以满足城市人口增长对蔬菜的需求。与此同时，1987年至1999年间其他土地覆盖类型持续减少：水体从30.4%降至23.8%，林地从33.6%降至24.3%。我们发现城市用地的扩张至少在一定程度上导致了相对自然栖息地的减少，如城市森林和湖泊水域。这些变化已造成了重大的负面环境后果，包括湖泊萎缩、水质和空气质量恶化以及生物多样性丧失。
