全球气候变暖胁迫下的雅鲁藏布江流域植被覆盖度变化驱动机制探讨

为了解雅鲁藏布江流域内植被变化对气候变化响应的时空差异性,引入重心模型,分析和探讨了2002-2014年雅鲁藏布江流域植被的变化特点与气候因子的相关性。结果表明,植被的NDVI(归一化植被指数,Normalized difference vegetation index)重心与降水重心年际迁移方向具有正相关性。雅鲁藏布江流域的月植被NDVI受前0-1月降水影响最大,而不同季节植被的NDVI对降水影响表现出一定的滞后性,其中春季和冬季的植被NDVI均与前一季的降水呈现正相关性。该流域中乔木、灌木对降水反应的滞后性比草本植物要大;生长季的温度变化与植被的生长具有相关性。植被NDVI与月均温的正相关性达到最大的时间段差异较大。因此,植被NDVI和气候因子间的时空异质性研究对于雅鲁藏布江流域的生态环境保护具有重要意义。

Driving Mechanism of Vegetation Coverage Change in the Yarlung Zangbo River Basin under the Stress of Global Warming

The Yarlung Zangbo River Basin, located in Qinghai-Tibet Plateau, is an important region of the World biological diversity and ecological landscape protection, which fragile environment is significantly affected by global warming. In order to understand the spatial-temporal difference of vegetation coverage in Yarlung Zangbo River Basin response to climate change, the correlation between vegetation coverage and climatic factors in 2002-2014 was analyzed by center of gravity model. The results showed that there was a positive relation in migratory direction of gravity center between vegetation NDVI and interannual precipitation. The monthly NDVI of vegetation was mostly affected by precipitation of 0-1 month before. There was also a time-lag effect between seasonal NDVI of vegetation and precipitation, and there was a positive relation between NDVI of vegetation in spring and winter and precipitation of prior season. Meanwhile, the time-lag effect of trees and shrubs on precipitation was bigger that of herbs. The vegetation growth had relation with the temperature change in growing season. Correlation coefficients between month mean temperature and NDVI of vegetation reached up to the maximum value had significant differences. The spatial and temporal heterogeneity between NDVI of vegetation and climatic factors is of great ecological significance for the protection of eco-environment in Yarlung Zangbo River Basin.