基于MODIS NDVI汉江中游植被时空变化及其地貌分异分析

基于2001~2015年的时间序列MODIS NDVI数据,通过逐像元线性趋势回归和回归系数计算,分析汉江中游地区植被年均NDVI变化的时空规律;通过植被时空变化的地貌分异分析,评估人类活动的影响及其空间差异。研究结果表明:汉江中游地区近15 a来,植被年均NDVI值呈现明显的波动增长趋势;植被时空变化表现出一定的地貌分异规律,平原、河漫滩、台地植被年均NDVI呈现明显的增长趋势,而丘陵、低山和中山植被年均NDVI增长趋势不明显。不同地貌类型区年均NDVI值变化受人类活动影响程度的强弱依次为:平原、台地、河漫滩、丘陵、低山、中山。人类活动是汉江中游平原区年均NDVI稳定增长的主要原因。

SPATIAL-TEMPORAL CHANGES OF VEGETATION AND ITS GEOMORPHIC DIFFERENTIATION IN THE MIDDLE REACHES OF THE HANJIANG RIVER BASED ON MODIS NDVI DATA

In recent years,the middle reaches of the Hanjiang River are experiencing complex climate change and human activities synergistic interference.It is of great significance that we evaluate the impacts of human activities and climate change on the vegetation such that we could make better decisions in natural resource and environmental management.In this work,we used remote sensing data to address this problem.First and foremost,based on the NDVI generated using MODIS data from 2001 to 2015,we analyzed the spatial and temporal patterns of the annual average vegetation NDVI variations in the middle reaches of Hanjiang River using pixel-by-pixel linear regression and goodness-of-fit calculation.Moreover,we also used geomorphic differentiation analysis to assess the impacts and spatial heterogeneity of human activities.The results indicate that there has been a fluctuating growth in the annual average vegetation NDVI in the study area in the past 15 years.The temporal-spatial NDVI variations of the vegetation reflect the patterns of geomorphological heterogeneity.The temporal-spatial variations in different geomorphological areas have different spatial and temporal characteristics.Specifically,the annual average vegetation NDVIs of plains,flood plains and platforms have increased significantly,while those of hills,low mountains and middle mountain vegetation have experienced little growth.Human impacts also vary with geomorphology.The ranking of different landform types with regard to the impacts of human activities on the annual average their vegetation NDVI variation (from strong to weak) is as follows:plain,platform,flood plain,hill,low mountain,and middle mountain.Finally,we conclude that human activities are the main reason for the steady growth of annual average NDVI in the plain area of the middle reaches of the Hanjiang River.