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利用GIMMS和SPOTVGT两种归一化植被指数(NDVI)数据对青藏高原地区1982—2009年期间草地覆盖的时空变化进行研究,结果如下:①青藏高原草地植被覆盖的年际变化存在着显著的空间差异。趋于升高的区域主要分布在西藏的北部和新疆的南部;趋于下降的地区主要分布在青海的柴达木盆地、祁连山、共和盆地、江河源地区及川西地区。②青藏高原草地覆盖度年际变化趋势分析表明,在90%的显著性检验水平上,降低和增加面积的比率为0.31,草地植被覆盖水平总体趋于升高态势。③以10 a为步长的分析表明:草地盖度呈现持续增加的区域主要分布在西藏北部;阿里地区草地盖度表现为先减少后增加;雅鲁藏布江流域草地盖度呈现先增加而后减少;而持续减少的区域主要分布在青海省以及川西地区,其中青海省分布最广;统计结果显示,高原大部分地区草地盖度具有升高的态势。
The temporal and spatial variations of grassland cover during the period from 1982 to 2009 in Qinghai-Tibet Plateau were studied by using the two normalized NDVI data of GIMMS and SPOTVGT. The results are as follows: ① There is significant space for interannual variability of grassland vegetation cover in the Tibetan Plateau difference. The areas that tend to go up are mainly located in northern Tibet and southern Xinjiang; the areas that tend to decline are mainly located in the Qaidam Basin, the Qilian Mountains, the Gonghe Basin, the Jiangheyuan and the western Sichuan areas in Qinghai. Analysis of interannual variability of grassland coverage in the Qinghai-Tibet Plateau shows that the ratio of decreasing and increasing the area is 0.31 at 90% significance level, and the coverage of grassland vegetation tends to increase. ③analysis in 10-year increments showed that the areas with the continuous increase of grassland coverage were mainly distributed in northern Tibet; the grassland coverage in Ali area decreased first and then increased; the grassland coverage in the Brahmaputra basin first increased and then decreased; The reduced areas are mainly distributed in Qinghai Province and western Sichuan area, of which Qinghai Province is the most widely distributed; the statistical results show that grass cover in most parts of the plateau has an upward trend.