青藏高原NDVI时空变化特征研究(1982—2008)

Temporal and Spatial Variation of NDVI in Tibetan Plateau from 1982 to 2008

利用1982—2000年AVHRR-Path Finder植被指数数据、2001—2008年SPOT-Vegetation植被指数数据,验证了两个遥感产品具有较好的延续性,可以用于时间序列植被特征分析。利用合成的归一化植被指数(Normalized Difference Vegetation Index,NDVI)数据集,分析得出了从1982年至2008年青藏高原地区植被NDVI的时空变化特性。结果表明:(1)时间序列上,该地区NDVI的最大值和平均值均未超过0.4,表明整个青藏高原地区的植被覆盖度低;NDVI整体呈现缓慢上升趋势;四季的变化表现秋季NDVI值缓慢上升,其他季节变化趋势不明显。(2)该地区NDVI空间格局分析发现NDVI变化率最高达到0.024/27 a,最低在-0.025/27 a;整体趋势呈现由东南地区向西北地区递减;季节的空间格局分析发现大部分区域在春、夏和秋季上升,而冬季下降,春夏秋3个季节NDVI的变化区域比冬季更广泛,冬季的植被覆盖变化除西藏东南的少部分地区以及云南西北部的少部分地区有明显变化外,整个青藏高原地区的其他大部分地区变化基本不明显。

The long term documents of AVHRR-Path Finder（ 1982—2000） and SPOT-Vegetation NDVI（ 2001—2008） were chosen to analyze the change trend of normalized difference vegetation index（ NDVI）in Tibetan Plateau. The results show that（ 1） the maximum of NDVI in this region is no more than 0. 4,which illustrates the low vegetation coverage in Tibetan Plateau; the value of NDVI presents the slowly rising trend. Moreover,the seasonal change of NDVI is increased slowly in autumn.（ 2） The slope of NDVI is from 0. 024 /27 a to-0. 025 /27 a; and it presents decreasing trend from southeast to the northwest in Tibetan Plateau; the features of spatial variations in spring,summer and autumn are increasing in most region of Tibetan Plateau. While the changes of region in spring,summer and autumn are wider than that in winter.The change of vegetation coverage in most of the Tibetan Plateau is not obvious except the southeast area in Tibet and the minority areas in the northwest of Yunnan province.