青藏高原植被覆盖变化及其与气候变化的关系

Variations of Vegetation Coverage and Its Relations to Global Climate Changes on the Tibetan Plateau during 1981—2005

近几十年来,全球气候变化对青藏高原植被覆盖产生了重要影响。基于青藏高原1981—2005年遥感影像及同期气象数据,结合生态学模型,分析了青藏高原植被覆盖度变化趋势及其与气候变化的关系。结果显示,25 a间,青藏高原温度升高、降水量增加,植被覆盖度呈"整体升高、局部退化"趋势;地表植被改善区主要位于植被低覆盖区,退化区主要位于高覆盖区;从不同植被类型看,除针叶林、阔叶林受采伐影响覆盖度下降外,其他植被覆盖度均不同程度的上升;植被覆盖度变化与同期降水量变化、温度变化均呈正相关,且具有明显的区域差异。

Recent global climate changes have an important effect on vegetation coverage on the Tibetan Plateau. Based on the remote sensing images and the meteorological data during 1981--2005, as well as the model of extrac- ting vegetation coverage, the spatial-temporal variations of vegetation coverage and its responses to global climate changes on the Tibetan Plateau were studied. The results revealed that, under the combination effects of the tem- perature rising and the precipitation increasing, vegetation coverage increased as a whole from 1981 to 200Y, except some degradation in small regions of the Tibetan Plateau. The degraded vegetation regions were mainly distributed in the area of higher vegetation coverage, while the improved vegetation regions were in the area of lower vegetation coverage on the Tibetan Plateau. The responses of vegetation coverage to global climate changes varied with differ- ent vegetation types. The vegetation coverage of needle-leaved forest and broad-leaved forest were decreasing due to the serious destruction of woods, while the other vegetation types were increasing. Global climate changes have con- tributed to an increase of vegetation coverage on the Tibetan Plateau, and the vegetation coverage changes were pos- itively correlated with the changes of precipitation and temperature during 1981--2005. The correlation between vegetation coverage changes and precipitation and temperature variations was obviously different in different regions.