Analysis of spatio-temporal characteristics of urban land cover and its landscape pattern: A case study in NanHai District of Foshan City

摘要

Land use/cover change is one of the three global environmental changes. The speeding land use/cover change process caused by the fast urbanization with significant economic development has remarkable influence on the urban environment. More and more attentions are paid on the effects of land cover changes on environment. NanHai District, which is located in the hinterland of Pearl River Delta, has a high intensive development on land use, for its advantageous location and highly developed economic. Accompanied with significant economic growth in last decade, NanHai District experienced a series of great changes in land use/cover change due to intensive human-induced activities. The most drastic change of land cover pattern was the transformation from dike-pond to other patterns, which results in eco-agriculture degradation and reduction of dike-pond. NanHai District is a typical represent of Pearl River Delta on land cover change. The data source of the research area mainly based on three phase of Landsat remote images. First, the method of FLAASH was used on the Landsat remote images for radiant correction, and then images were used for geometric correction with ENVI 4.5. Then, rivers and lake on the images were extracted and the edge was feathered. The Mahalanobis Distance supervised classification method combined with humancomputer interactive visual interpretation was used, and some field investigations were made to get the land cover pattern maps. Second, transfer matrix was generated by overlaying the maps of different issues. At last, ten index (Number of Patches, Patch Density, Largest Patch Index, Landscape Shape Index, Fractal Dimension Index-AW, Shannon's Diversity Index, Contagion Index, Patch Cohesion Index, Splitting Index) calculated with FRAGSTARS 3.3 software were use to describe the total situation and speed of land cover change, and spatial-temporal feature of landscape pattern changes during the last 19 years. The results of quantitative analysi-s of land cover structure and its change show that the utilization degree index of cropland, meadow & forestland, dike-pond etc. have increased significantly with urbanization process, especially cropland. This tendency has been slight since 2000. From then on, the information and location of each land cover pattern began to change frequently, and presented the spatial differentiation of land cover. The results of analysis of landscape characteristic index and gradients show that the land use changes in NanHai District could be mainly described by decreased diversity, fragmentation tendency and decreased of cropland.