天山北坡植被NDVI时空变化及其与气候因子的关系

Spatiotemporal Variation of Vegetation NDVI and Its Relationship with Climatic Factors on the Northern Slope of the Tianshan Mountains

利用MODIS NDVI数据产品并结合相应的气候数据,运用一元回归趋势分析法,相关分析法,探讨2000-2015年天山北坡年平均、月平均NDVI时空变化与气候因子的相关关系。结果表明:①近16 a来,天山北坡年平均NDVI值在0.27~0.31之间波动上升,总体上呈明显增加的趋势;月平均NDVI值每年4月开始植被覆盖迅速增加,到7月达到最大值,然后8月开始降低,月平均NDVI值的变化呈现出单峰趋势。天山北坡不同季节植被指数都呈现上升的趋势。空间上天山北坡植被覆盖呈现出西部高东部低,南部高北部低的分布特征。生长季植被NDVI值和年平均植被NDVI值的变化存在明显的空间差异,表现为中部植被覆盖增加,东北部、西部、南部的植被覆盖减少。②天山北坡年平均气温和平均降水量逐步上升,变化趋势表现为上升-下降-上升的趋势。空间上天山北坡南部山地地区气温低,降水量多;北部平原区气温高,但降水量少。③NDVI值对气温和降水量存在一定的相关关系。气温与降水量对植被的生长均有影响,其中春季的植被NDVI值与气温的关系密切,夏季的植被NDVI值与降水量有密切的关系,综合分析,降水量对植被覆盖的影响大于气温对植被覆盖的影响。④生长季(5-9月)植被NDVI值与气温和降水量存在一定的滞后性。

In this paper,the monadic regressive analysis was employed to investigate the annual and monthly as well as spatial variations of vegetation NDVI on the northern slope of the Tianshan Mountains from 2000 to 2015 based on the MODIS NDVI data and the corresponding climate data.The results are as follows:①In recent 16 years,the average annual NDVI on the northern slope of the Tianshan Mountains fluctuated between 0.27 and 0.31 and in a significant increase trend.The average monthly NDVI value began to increase rapidly in April,reached its maximum in July,and then began to decrease in August.The curve of average monthly NDVI was unimodal.The increase of vegetation index on the northern slope of the Tianshan Mountains was different from different seasons.Spatially,the vegetation coverage was high in the west and south but low in the east and north.There was a significant spatial difference of average annual vegetation NDVI and NDVI in growing season,and the vegetation coverage was increased in the central area but decreased in the northeast,west and south;②The average temperature and precipitation on the northern slope of the Tianshan Mountains in the past years were gradually increased and in an increase-decrease-increase fluctuation trend.Spatially,the temperature was low but the precipitation was high in the southern mountainous region,the situation in the northern plain,however,was opposite;③There was a certain correlation between the vegetation NDVI and the temperature and precipitation,especially in growing season.The vegetation NDVI in spring was more closely related to the temperature,but in summer was more closely related to the precipitation.Comprehensively,and the effect of precipitation on the vegetation coverage was higher than that of temperature;④There was a hysteresis of vegetation NDVI than the temperature and precipitation in growing season from May to September.