Vegetation coverage dynamics and its response to urbanization in the Taihu Lake Basin during 1998∼2010

Abstract

Based on the DMSP/OLS nighttime lighting data, the temporal and spatial evolution patterns of urbanization in Taihu Lake Basin from 1992 to 2010 were illustrated. In the meantime, the dynamic change characteristics of vegetation cover in Taihu Lake Basin from 1998-2010 were revealed according to the annual maximum ten-day normalized vegetation NDVI index and the corresponding vegetation coverage rate of SPOT in 1km × 1km resolution. Subsequently, the temporal and spatial response characteristics of vegetation cover factor to urbanization were also identified. The results showed that the urbanization process of the Taihu Lake Basin has been accelerated substantially since the beginning of the 1990s, and the intensity of nighttime and human activity has continuously increased. The urban built-up area has expanded extensively in the eastern part of the basin. Although the annual maximum ten-day normalized vegetation index NDVI and vegetation coverage in the whole basin over the past more than 10 years did not exhibit significant decline or class difference, there were significant negative temporal correlations of the annual maximum NDVI index and the vegetation coverage with the light intensity in the surrounding area and the corridors of main communication. As a result, the vegetation coverage in Puxi, Pudong, Yangcheng-Dianmao, and WuchengXiYu exhibited continued downward trends. At the same time, there was a close relationship between the spatial pattern of vegetation coverage and the pattern of urbanization in Taihu Lake Basin. On the spatial scale of 1km × 1km, there were significant negative correlations between NDVI and light intensity in the whole basin except for the Taihu Lake area over all the investigated years. Since the rapid urbanization of the Taihu Lake Basin has a significant effect on vegetation cover characteristics, it is necessary to reinforce the ecological protection, restoration and other measures to scientifically respond and prevent changes in vegetation cover caused by the ecological environment and hydrological risks.