基于结构方程模型的安徽省归一化植被指数变化及影响因素分析

Analysis on the Normalized Difference Vegetation Index Change and Influence Factors in Anhui Province Based on Structural Equation Model

定量研究植被变化的影响因素,对区域生态环境保护和治理具有重要现实意义。以安徽省为例,基于GEE(Google Earth Engine)云平台获取MOD13Q1 NDVI数据,辅以一元线性回归分析法,分析2000—2018年安徽省归一化植被指数(normalized difference vegetation index,NDVI)时空变化特征和变化趋势,并采用结构方程模型(structural equation model,SEM)量化气候、地形及人类活动对NDVI变化的影响。结果表明:2000—2018年安徽省NDVI随时间变化呈现波动增加趋势。大部分地区为中高和高植被覆盖度,植被空间变化趋势以改善为主,改善区域占研究区面积的81.43%,主要分布在皖南黄山、宣城、池州,皖中滁州、六安、安庆北部及皖北淮南。夜间灯光变化能较好地衡量人类活动变化,对NDVI变化的负向影响最大。地形对皖南山区NDVI变化影响较强,皖中次之,而皖北平原NDVI变化基本不受地形影响。气候变化对皖北和皖中地区NDVI变化影响较强。

It is of great practical significance for regional ecological environment protection and management to quantitative study on the driving factors of vegetation change.Taking Anhui Province as an example,based on MOD13Q1 NDVI data obtained by Google Earth Engine(GEE),with the univariate linear regression analysis,the spatial-temporal variations and trend of normalized difference vegetation index(NDVI)in Anhui Province from 2000 to 2018 were analyzed.The effects of climate change,topography and human activity change on NDVI change were quantified by structural equation model(SEM).The results show that the NDVI of Anhui Province shows an increasing trend with time from 2000 to 2018.Most areas in Anhui Province are medium high and high vegetation coverage.The spatial change trend of NDVI is mainly improved,the improvement area account for 81.43%of the study area,which mainly distribute in Huangshan,Xuancheng and Chizhou in southern Anhui,Chuzhou,Lu an,northern Anqing in central Anhui and Huainan in northern Anhui.Nighttime light change can better measure the change of human activities,and has the greatest negative impact on NDVI change.Topography have a strong impact on NDVI change in southern Anhui,followed by central Anhui,while NDVI change in northern Anhui is basically not affected by topography.Climate change has a strong impact on NDVI change in northern and central Anhui.