粤北岩溶山区连江流域植被覆盖度动态变化研究

Regime of vegetation coverage in Lianjiang Watershed in North Guangdong Karst Mountain

基于多时相MODIS数据和归一化植被指数的像元二分模型以及GIS技术,分析了2001—2010年连江流域植被覆盖度的时空变化特征。结果表明:连江及其子流域、岩溶区与非岩溶区的植被覆盖度空间分布差异性明显;近10年来连江流域的植被覆盖度总体上呈下降趋势,高植被覆盖度与中度植被覆盖度的面积数量变化剧烈,较高植被覆盖度与较低植被覆盖度的面积相对稳定;岩溶区植被分布以较高植被覆盖度、中植被覆盖度和高植被覆盖度为主,其分布面积分别占整个流域面积的53.84%、25.59%、18.54%,而非岩溶区则以高植被覆盖度、较高植被覆盖度和中植被覆盖度为主,分别占整个流域面积的48.12%、34.10%、15.05%;近10年来流域的植被覆盖度下降明显,且空间分布范围广,植被覆盖度相对稳定的区域占整个流域面积的65%以上,植被覆盖度下降区的面积比上升区增加近20%。

The spatial and temporal regimes of the vegetation cover from 2001 to 2010 in the Lianjiang Watershed are analyzed by means of the multi-temporal MODIS-NDVI and GIS and the dimidiate pixel model techniques in this paper.The results show that there is obvious otherness in vegetation covers between the Lianjiang watershed and its sub-streams and between karst and non-karst areas;and the vegetation coverage keeps decreasing in the recent 10 years with the high coverage and medium coverage areas undulating sharply,but the comparatively high or low coverage areas keeping stable.The karst area are mainly composed of high（53.84%）,medium（25.59%） and comparatively high（18.54%） vegetation coverage,but comparatively high（48.12%）,comparatively high（34.10%） and medium（15.05%） in no-karst area.The vegetation coverage has been clearly decreased in the recent 10 years as a whole and the vegetation coverage decreasing area is 20% more than the increasing area.