归一化植被指数对降水量变化的响应研究

Response of Normalized Vegetation Index to Precipitation Change

【目的】植被覆盖变化与降水量的关系研究,对分析植被生态系统在气候变暖导致降水量发生变化背景下的响应具有重要意义。【方法】本文利用托里县2011-2015年归一化植被指数(NDVI)与TRMM卫星降水量数据,分析归一化植被指数NDVI和TRMM卫星降水量在托里县多年来的时空变化趋势,实现了降水量与NDVI数据的移动平滑,探讨了NDVI与TRMM卫星降水量随时间的动态变化,并对NDVI和降水量的相关性进行了讨论。【结果】①TRMM卫星降水量与NDVI两者的趋势变化呈现相辅相成;从空间分布特征角度而言,NDVI的空间分布规律往往呈现与同期或前期TRMM降水量空间分布特征相似,影响NDVI的因子众多,降水量变化不能全面的解释NDVI的动态变化;②从时间角度而言,降水量与NDVI存在时间上的梯度关系,降水量增加后,NDVI才逐步随之增大。综合空间分布特征和时间变化特征,均证明降水量对NDVI的影响作用具有典型的滞后性;③5年里的NDVI与TRMM卫星降水量相关性较为显著,NDVI与TRMM卫星降水量之间的相关性大多呈正相关,TRMM卫星降水量能促进NDVI的增加。【结论】降水对植被生长具有显著的驱动力作用,伴随降水量的变化,植被覆盖情况会随之慢慢产生相同的变化特征。

【Objective】The study of the relationship between vegetation cover change and precipitation is greatly significant in analyzing the response of vegetation ecosystem to the change of precipitation caused by climate warming.【Method】This paper analyzed the spatial and temporal trends of NDVI and precipitation by TRMM with the data in Tory County from 2011 to 2015, achieve smooth movement between precipitation and NDVI data, and discussed the dynamic changes of NDVI and precipitation by TRMM and the correlation between NDVI and precipitation.【Result】(i)The trend of NDVI and precipitation TRMM were complementar,and by the perspective of spatial distribution characteristics, the spatial distribution of NDVI tends to be similar to precipitation during the same period or the previous period. The dynamic changes of NDVI cannot be fully explained, because the impact factors of NDVI and the precipitation were numerous;(ii)From the time point of view, the gradient relation between the precipitation and the NDVI by time, and the NDVI gradually increases after the precipitation. It proves that the precipitation has a typical hysteresis effect on NDVI by spatial distribution characteristics and temporal variation characteristics;(iii)The correlation between NDVI and precipitation by TRMM is significantly positive correlation in 5 years, precipitation by TRMM can promote the increase of NDVI.【Conclusion】Precipitation has a significant driving effect on vegetation growth, the vegetation cover will change characteristics gradually with the precipitation.