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

Abstract:

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.

Key words:Vegetation;Coverage;Climatic factor;Yarlung Zangbo River Basin;Model of gravity center