1990-2019年澄碧河流域NDVI时空动态及驱动因素分析

Spatiotemporal Variation of NDVI and Its Driving Factors Analysis in Chengbihe Basin from 1990 to 2019

为了解西南喀斯特流域的植被恢复状况及其驱动因子,以澄碧河流域为例,基于GEE平台和1990—2019年研究区Landsat遥感影像,采用Sen+Mann-Kendall趋势、偏相关等方法,分析了澄碧河流域归一化植被指数(NDVI)时空演变特征与驱动力。结果表明:1990—2019年澄碧河流域NDVI总体呈波动上升趋势,年平均增速为0.0046,植被呈显著改善的区域占87.09%;不同土地利用类型下,NDVI均值排序为常绿灌木地>常绿阔叶林>常绿针叶林>落叶阔叶林>旱地>草地>水田;NDVI随海拔上升呈先增加再缓慢下降再缓慢上升的趋势,随坡度的增加呈先缓慢上升再缓慢下降的趋势;澄碧河流域88.88%区域NDVI与气温具有正相关关系,其中显著正相关占20.75%,与降水量变化相关性较小,仅有1.14%区域通过p<0.05显著性水平检验。总体而言,澄碧河流域植被得到显著改善,温度变化和人类活动一定程度上促进了流域植被的生长。

In order to understand the restoration of vegetation and its driving factors in the southwest karst basin,Chengbihe Basin was taken as an example,based on GEE platform and Landsat remote sensing images from 1990 to 2019,Sen+Mann-Kendall trend and partial correlation method were used to analyze the spatiotemporal evolution characteristics and driving forces of NDVI in the Chengbihe Basin.The results show that the NDVI in the Chengbihe Basin showed a fluctuating upward trend in 1990—2019,with an average growth rate of 0.0046 per year,and the area with significant improvement in vegetation accounted for 87.09%;under different land use types,the average value of NDVI was ranked as shrubland>evergreen broad-leaved forests>evergreen needle-leaved forest>open deciduous broadleaved forest>rainfed cropland>grasslands>irrigated cropland;NDVI with the rise of altitude showd the trend of increasing at first and then slowly decreasing and then slowly rising,showing a trend of slow rise and then slow decline with the increase of slope;NDVI in 88.88%of the area of Chengbihe Basin had a positive correlation with temperature,of which 20.75%was significantly positive correlation,which was less correlated with precipitation change,and only 1.14%of the region passed the p<0.05 significance level test.On the whole,the vegetation of Chengbihe Basin has been improved significantly,and temperature change and human activities have promoted the growth of vegetation in the basin to some extent.