艾比湖流域降水和风速对植被NDVI时空变化的影响

Effect of Precipitation and Wind Speed on NDVI in Aibi Lake

【目的】归一化植被指数NDVI(Normalized Difference Vegetation Index)不仅可以很好的反映地表植被的繁茂程度,而且是指示植被活动和植被生产力的良好指标之一。【方法】本研究采用2004年12月至2014年11月的MODIS卫星影像、TRMM卫星数据,辅以站点监测的气温和风速数据,分析植被NDVI在10年间的不同季节的时空变化特征,探讨降水量对植被NDVI产生的影响,剖析植被覆盖与风速、气温之间的相关关系。【结果】(1)10年间植被NDVI在研究区内呈现出夏季>秋季>春季>冬季的空间分布特征,在春季体现出自西向东NDVI逐步减少的趋势,夏季和秋季的植被NDVI由西南至东北逐步降低;(2)春季、夏季和秋季,降水量都呈现出由西南到东北方向逐步降低的分布特征,冬季降水量呈现了由西向东逐步递减的分异特征;(3)降水量与植被NDVI之间呈正相关的关系,相关系数表现为冬季<春季<夏季<秋季,降水对植被NDVI有驱动作用,但这种影响具有一定的时间滞后性。(4)平均风速在空间格局上都呈现出条带性的分布特征;(5)植被NDVI在夏季和秋季均与气温呈负相关关系,但与降水量呈正相关关系,与温度相比,水分条件才是影响植被生长的主导因素。【结论】本文筛选了3个气候因子,能为更全面的剖析气候变化对植被变化的影响过程起到参考作用。

[ Objective] NDVI （ Normalized Difference Vegetation Index） not only reflected the lush degree of surface vegetation, but also one of good indicators of vegetation activity and productivity. [ Method] In this study, the MODIS satellite images, TRMM satellite data, supple- mented by the site monitoring temperature and wind speed data from December 2004 to November 2014 were used to analyze the temporal and spatial variations of NDVI in different seasons of ten years, discuss the effect of precipitation on NDVI and dissect the relationship between vegetation cover and wind speed and temperature. [ Result] （i） For ten years, NDVI showed a trend of summer 〉 autunm 〉 spring 〉 winter in the study area; NDVI gradually decreased from west to east in the spring and decreased gradually from southwest to northeast in summer and autunm; （ii） The precipitation decreased from southwest to northeast in the spring, summer and autunm and decreased from west to east in winter; （iii） There was a positive correlation between precipitation and NDVI, the correlation coefficient showed winter 〈 spring 〈 summer 〈 autunm, and the precipitation had a driving effect which had time lag on NDVI ; （iv） The average speed of wind showed striped distribu- tion in the spatial pattern ; （v） There was a negative correlation between temperature and NDVI in summer and autunm, but a positive corre- lation with precipitation. Compared with the temperature, the water condition was the dominant factor affecting vegetation growth. [ Conclu- sion] This study selected three climatic factors, which could be used as a reference for the more comprehensive analysis of the effects of cli- mate change on vegetation change.