春末夏初青藏高原植被对全球变暖响应的区域特征

Regional Pattern of Vegetation Responses to Global Warming in the Qinghai-Tibet Plateau during Late Spring and Early Summer

利用1982—2002年Pathfinder NDVI遥感数据,采用REOF和倾向度趋势分析方法,研究了5～6月青藏高原地表植被变化区域特征及与全球变暖的关系。21年来高原区域春末夏初植被变化存在明显的空间差异,且存在一个位于高原南北呈带状分布的植被显著变化区域。该区域内植被对全球气温变暖响应显著,与前期5月北半球平均气温相关系数达到0.7675,通过0.001显著性水平检验;植被NDVI随气温升高呈现出显著一致的增加趋势,增长速率超过10%/10 a,是全球变暖响应的显著区和敏感区。进一步的分析表明,对植被全球变暖响应显著的区域基本上处于高山山脉或半荒漠NDVI值低于0.12覆盖度较低的区域。不同植被类型对变暖响应的对比表明,草地对全球变暖响应明显高于林地,其植被NDVI 21年约增加10%。

Using the satellite-observed Normalized Difference Vegetation Index （NDVI） dada and Rotated Empirical Orthogonal Function （REOF） method, the spatial-temporal characteristics and trends of the late spring and early summer （May-June） vegetation change in the Qinghai-Tibet Plateau from 1982 to 2002 are analyzed. It is found the months with the strongest responses to global warming on the area of northern and southern two zones, the northern zone from eastern of Kunlunshan to Qilian Mountain and southern zone along the northern edge of central Himalayas eastward to Henduan Mountain Range. The May～June vegetation in the two zones increase significantly with global warming, by a 10% increased percentage for decades and with a correlation coefficient of 0. 7675 at 0. 001 significant levels between the first REOF of May～June vegetation and the May surface air temperature averaged for Northern Hemisphere during 1982-2002. Moreover, the areas with grassland or low biomass in the mountain and semidesert zones （NDVI usually less than 0. 12） respond more evidently to global warming than those with moderate and high biomass.