青藏高原植被活动对降水变化的响应

为揭示气候变异对青藏高原植被生长的影响，根据2000-2004年间增强型植被指数(EVI)数据和研究区内43个气象台站的气候资料，研究了近5年来青藏高原植被活动及其与气候因子的关系。结果显示，青藏高原植被的EVI呈现由东南向西北递减的分布格局，降水是导致植被覆盖空间变化的主要因素；2000?2004年青藏高原植被活动的年际变化总体上不显著，局部出现较大变异；EVI的变异系数(CV)与年降水的变异系数显著正相关，说明降水波动是引起植被活动变化的主要因素。此外，EVI 的CV与年降水量存在着显著的负相关关系，表明年降水量越大的地区植被活动的年际变化越小，即植被的稳定性越大。

Responses of Vegetation Activity to Precipitation Variation on the Tibetan Plateau

To reveal the effects of climate change on the Tibetan Plateau,the Enhanced Vegetation Index(EVI)data of 2000-2004 together with the climate data from meteorological stations in the study area is used to analyze the vegetation cover,variations and the relationships between climate factors.The primary results show as follows:(1)EVI decreases from southeast to northwest on the Tibetan Plateau,which resulted from the precipitation;(2)Vegetation growth keeps stable on the whole,with obvious variation in some areas;(3)EVI variations mainly come from precipitation variation.Coefficient of Variation(CV)of EVI shows significantly positive relation to precipitation CV,but has no relation in evidence to temperature CV;(4)EVI CV shows significant negative relation to precipitation,which means vegetation growth in areas with more precipitation varies less strongly.