利用来自青海湖流域乌兰和天峻的树轮指数和1982—2003年逐月标准化植被指数(NDVI)数据及气候数据,在分析树轮指数及草地NDVI与气候因子关系的基础上,探讨了树轮宽度指数序列与青海湖布哈河流域草地NDVI之间的关系.结果表明:树轮宽度指数及草地NDVI主要受6-8月份的水热条件的影响,温度与同期树轮宽度指数及草地NDVI具有较高的正相关,而降水的影响存在滞后性.树木年轮指数序列与6-8月草地NDVI有显著的相关关系,与8月份的NDVI相关性最强.树轮指数与草地NDVI间的显著相关性为研究该地区草地过去的动态变化提供了基础,利用乌兰和天峻的两条树轮指数重建了8月份NDVI的千年变化.
In this paper,using tree ring indices and monthly normalized NDVI and meteorological data in Wulan and Tianjun Counties form 1982 to 2003,the relationships between tree ring indices and grass NDVI in Buha River basin are analyzed on the basis of the relationships between tree ring indices,grass NDVI and climatic factors.It is found that water-heat conditions distinctly affect the tree ring indices and grass NDVI from June to August.Between air temperature and tree ring indices,grass NDVI in the same period there is a significant correlation.However,the effect of precipitation lags behind air temperature.A remarkable correlation exists between the series of tree ring indices and grass NDVI from June to August,especially in August.The significant correlation between tree ring indices and grass NDVI will be in favour of studying the grass dynamic change in the past.A thousand year variations of grass NDVI in August are reconstructed in this paper based on two tree ring series in Wulan and Tianjun counties.