不同城市化阶段景观演变的热环境效应动态——以深圳西部地区为例

热环境效应是城市化过程中景观格局演变对区域生态环境影响研究的重要内容之一。通过热环境效应动态研究有助于理解景观对区域生态环境效应的影响在不同阶段的规律特性。本文利用深圳市1987年、1995年和2005年3期Landsat TM影像,通过构建热环境效应变化指数描述不同城市化阶段热环境效应的发展特征,并通过景观分布指数表征景观演变对其的影响作用。结果表明热环境效应的空间特征在城市化进程中由聚集型逐渐转变为零散与破碎分布;在快速城市化阶段,景观演变对热环境效应动态的影响主要体现为热中心的扩展,同时自然景观对热环境效应的缓解作用有所减弱;城市化稳定阶段,景观变化的热环境效应由空间的扩张转为强度的提高。

Thermal environment effect dynamic of landscape changes in different urbanization phases: A case study of western Shenzhen

Urban thermal environment effect is one of the hotspots of the research on the eco-environmental effects of landscape changes. Research on urban thermal environment effect dynamics can help to get a better understanding the influence of landscape changes in a specific phase. The objectives of this study are: (1) to analyze spatial and dynamics characteristics of urban thermal environment effect based on thermal environment effect index and change index; (2) to assess the influences of landscape change on thermal environment effect by distribution index. Based on Landsat Thematic Mapper images acquired on January 6, 1987, December 30, 1995, and November 23, 2005, the landscape classifications of Shenzhen were conducted on supervised classification. The surface temperature was derived from TM thermal infrared data by mono-window algorithm. Urban thermal environment effect index was defined to describe the spatial characteristics of thermal environment effect. Dynamics of thermal environment effect was characterized by change index based on urban thermal environment effect index. To assess the influences of landscape changes on thermal environment effect, this paper used distribution index. Urban thermal environment effect index demonstrates that thermal spatial characteristic is changed from congregating distribution to fragment. The dynamics of thermal environment effect in different urbanization phases display different spatial characteristics, and are influenced by different landscape change impact factors. In the rapid urbanization phase (1987-1995), landscape changes are intense. In this phase, thermal centers expanded to the edge of the city. Thermal environment effect of natural landscape increases in this phase. It indicates that natural landscape has changed in its composition and quality in rapid urbanization phase. Then, the city comes to a relatively steady urbanization phase (1995-2005). The rate of landscape changes slows down. In this phase, the importance of thermal spatial expansion is weaker than in the first phase. The increasing thermal environment effect in urban landscape is prominent.