雅鲁藏布江流域植被覆盖变化及其对气候变化的响应

基于雅鲁藏布江流域2000—2016年MODIS遥感产品,选取植被归一化指数NDVI研究近年来研究区植被覆盖变化情况,并结合流域内气象站实测数据,采用趋势分析法、Hurst指数法和偏相关系数法研究流域植被覆盖变化及其对气候变化的响应关系。结果表明:近年来流域上游和下游地区植被覆盖以改善为主,中游地区则以恶化为主;流域低海拔地区为NDVI高值区,植被覆盖度随海拔升高呈先稳定后下降再稳定的趋势;流域NDVI与气温的偏相关系数大于降水,说明雅鲁藏布江流域整体上植被生长受气温影响要大于降水;流域Hurst指数空间差异性显著,均值为0.51,说明流域植被覆盖整体呈弱可持续性,其中拉萨河流域及雅鲁藏布江上游地区空间持续性较强,达到0.74。

Spatiotemporal variability of vegetation cover and its response to climate change in Yarlung Zangbo River Basin

Based on the MODIS remote sensing products from 2000 to 2016 in the Yarlung Zangbo River Basin, the Normalized Difference Vegetation Index(NDVI)was adopted to demonstrate the changes of vegetation cover. Combined with the measured data from the meteorological stations in the basin, the trend analysis method, Hurst index method, and partial correlation coefficient method were used to investigate the response of vegetation cover to climate change. The results show that the NDVI in the upstream and downstream region in recent years was mainly improved, while that in the middle reaches was mainly deteriorated. The high value of NDVI was located in the low elevation area. The trend of vegetation cover against elevation was firstly stable, then downward, and finally stable again. The correlation coefficient between NDVI and temperature in the Yarlung Zangbo River basin was greater than that with precipitation, indicating that the impact of temperature on the growth of vegetation in the Yarlung Zangbo River Basin is much stronger than that of precipitation. The Hurst index across the whole basin showed a significantly spatial heterogeneity, with an average value of 0. 51, indicating that the NDVI of the Yarlung Zangbo River Basin showed a weak sustainability. The spatial sustainability of the NDVI in the Lhasa River Basin and the upper reaches of the whole basin was relatively strong, reaching the value of 0. 74.