汾河流域2001—2013年植被覆盖时空变化及其对气候因子的响应

Spatial and Temporal Dynamics of Vegetation Cover from 2001 to 2013 and Its Response to Climatic Factors in Fenhe River Basin

利用2001—2013年汾河流域卫星遥感数据归一化植被指数(NDVI)、地表温度(LST)和降水实测资料,分析了汾河流域及其上、中、下游近13 a来NDVI的时空变化特征及其对气候因子的响应。结果表明,近13 a汾河流域月NDVI变化呈现单峰型;整个流域及上、中、下游的植被覆盖率均有所提高;植被覆盖状况由西北向东南逐渐变好;基于月尺度的NDVI与LST呈显著正相关,而降水量与NDVI的相关关系为抛物线型;基于月尺度的NDVI与同期的LST和降水量的复合相关模型优于单变量相关模型,复合相关模型为:NDVI=0.007Ts+0.002P+0.222;基于年际尺度的NDVI与LST的单变量相关不显著,而NDVI与降水量的单变量相关性显著;NDVI的赫斯特指数表明,汾河流域的植被覆盖状况将持续改善。

Based on the Normalized Difference Vegetation Index（NDVI）data from Moderate Resolution Imaging Spectroradiometer（MODIS）, the daily land surface temperature（LST）and precipitation data from 17 meteorological stations in Fenhe River basin of Shanxi province from 2001 to 2013, the paper analyzed spatiotemporal variation patterns of the vegetation cover in the basin and their correlations to climatic factors. The results showed that the change of vegetation index on monthly scale was a single peak. The vegetation cover index in the whole basin and the upstream, midstream and downstream showed a moderate increase trend. The vegetation coverage condition gradually got better from northwest to southeast. There was a significant positive linear correlation between the monthly average NDVI and the monthly mean LST in the basin, but the correlation between NDVI and precipitation was parabolic. The double variable model including LST and precipitation together for predicting the relationship between monthly mean NDVI and the monthly mean LST and precipitation was better than univariate correlation models. The double variable model was NDVI=0.007Ts＋0.002P＋0.222. At annual scale there was a weak correlation between NDVI and LST, but significant correlation existed between NDVI and precipitation.The Hurst exponent value calculated from NDVI showed that the vegetation cover of Fenhe River basin in Shanxi province would become better increasing with time.