阿克苏河流域不同植被类型NDVI时空变化特征

归一化植被指数(NDVI)是反映地表植被生长状况的一类敏感的光谱信号。利用NDVI反演新疆阿克苏河流域内的植被覆盖及动态变化特征,有利于及时准确地获取流域内植被的时空分布,在气候变化背景下深入研究阿克苏河流域植被的生长及变化特征,具有重要意义。根据土地利用类型划分标准,结合研究区现状,将阿克苏河流域植被分为林地、灌木林地、草地、园地和耕地共5种类型,利用2000年2月-2014年12月NDVI 16 d逐月合成数据,分析了研究区不同植被类型的NDVI在各生长阶段的数量变化特征,拟合了不同植被类型的生长状况及其变化曲线。研究结果表明:2000-2014年,阿克苏河流域林地、灌木林地和耕地的NDVI整体呈下降趋势,草地和园地的NDVI则呈现上升趋势;各类植被的NDVI最低值均出现在冬季(1-2月),峰值则出现在夏季(7-8月);NDVI值急剧上升阶段处于3-5月,下降阶段处于9-11月;耕地和园地覆盖度明显增加,林地、灌木林地和草地覆盖度则呈现减少趋势。

Spatial-temporal variation of different vegetation based on NDVI of Aksu river basin in Xinjiang

The normalized difference vegetation index (NDVI) is a kind of simple and sensitive spectral signal to reflect the vegetation growth. It is beneficial to capture the spatial-temporal distribution of vegetation by using NDVI to retrieve the vegetation cover and dynamic changes in Aksu River Basin. In the background of global climate change, it has important significance in studying on the vegetation growth and changes in Aksu River Basin. According to the classification of land use types and the characteristics of the research area, the vegetation of the study area was divided into 5 types: woodlands, shrub land, meadows, gardens and farmland. The changes of NDVI of different vegetation types in Aksu river basin were analyzed by using 16d NDVI data, from February 2000 to December 2014. It reflected the growth of vegetation types and the change curves. The results show that the NDVI of woodlands, shrub land and farmland from 2000-2014 in Aksu River Basin showed a downward trend, whereas the NDVI of meadows and gardens showed an upward trend. The minimum values of NDVI were in winter (January to February), while the maximum values of NDVI were in summer (July to August). From March to May, the NDVI value had been racing up, whereas from September to November, the NDVI value had been rapidly falling off. The coverage of farmland and gardens increased obviously but the coverage of woodlands, shrub land and meadows decreased.