基于MODIS影像的藏北草地植被覆盖度时空变化趋势分析

Temporal and Spatial Variation Trend of Grassland Coverage Based on MODIS Images in Northern Tibet

为探讨藏北地区2010~2018年草地植被覆盖度时空变化趋势和分布情况,本研究利用MODIS影像提取植被指数,计算藏北地区草地植被覆盖度,运用时空变化趋势模型分析藏北地区历年草地植被覆盖度变化和分布情况。结果表明:(1)藏北地区草地植被覆盖度总体呈现下降趋势,按相关性将变化趋势分为明显下降、轻度下降、轻度增长和明显增长。藏北地区草地植被覆盖度主要以轻度下降和轻度增长为主;(2)藏北地区植被覆盖度大多分布在10%~70%之间,年均植被覆盖度约20%左右;(3)藏北地区草地植被覆盖度变化较为明显,东部和北部地区植被覆盖度呈下降趋势,河流胡泊分布较多的中部和南部地区植被覆盖度呈增长趋势。结果说明利用MODIS影像数据,运用植被指数和时空变化趋势分析模型可以有效地反演草地植被覆盖度时空变化和分布情况。

In order to explore the temporal and spatial variation trend and distribution of grassland vegetation coverage in Northern Tibet during 2010 to 2018,this study uses MODIS Images to extract vegetation index,and calculates the grassland vegetation coverage,and uses temporal and spatial variation trend model to analyze the grassland vegetation coverage changes and distributions over the years in Northern Tibet.The results showed that:1)the vegetation coverage in Northern Tibet displayed a downward trend,which was divided into obvious decline,slight decline,slight growth and obvious growth according to the correlation,and the vegetation coverage of Northern Tibet mainly performed slight decline and slight growth;2)the mostly vegetation coverage of Northern Tibet distributed during 10%to 70%,and the average annual vegetation coverage was about 20%;3)the change of grassland vegetation coverage was obvious in Northern Tibet,while the vegetation coverage in the east and north was decreasing,and in the middle and south where are many lakes and rivers was increasing.The results confirmed that using vegetation index and spatiotemporal variation trend model based on MODIS images can effectively invert the spatiotemporal variation trend and distribution of grassland vegetation coverage.