2001—2020年中国森林植被EVI对气候因子的响应

Response of forest vegetation Enhanced Vegetation Index to climatic factors in China in 2001—2020

森林是陆地生态系统的主要组成部分,其在维持生物圈和大气圈的动态平衡中发挥着重要作用。探究森林生态系统植被指数变化及其对气候因子的响应对优化我国生态环境建设具有重要意义。基于2001—2020年MODIS-EVI数据及气象数据,利用趋势分析和偏相关分析等方法,探究中国森林生态系统生长季植被指数变化及其对气候因子的响应。结果表明,2001—2020年中国森林植被EVI以0.028/10a的速率增长,显著改善区占总面积的39.63%。生长季,植被指数与气温、降水量、太阳辐射和土壤湿度均呈正相关,其中土壤湿度对其影响最为显著,在中南地区尤为突出。EVI对各气候因子响应的时滞效应在不同地区之间存在差异:六个区域EVI对气温的响应均不存在时滞效应;对太阳辐射响应的滞后期均为3个月;西北地区、西南地区EVI对降水量响应的滞后期分别为3个月、6个月,华东地区EVI对土壤湿度的响应滞后期为6个月,其余地区EVI对降水量和土壤湿度的响应均不存在时滞效应。整体上看,土壤湿度是影响生长季植被变化的主要因子。

Forests are the main component of terrestrial ecosystems and play an important role in maintaining the dynamic balance of the biosphere and the atmosphere.It is of great significance to explore the change of vegetation index of forest ecosystem and its response to climate factors to optimize the ecological environment construction in China.In this study,based on MODIS-EVI(Enhanced Vegetation Index)data and meteorological data from 2001 to 2020,we investigated the changes of vegetation index in forest ecosystems and its response to climate factors during the growing season in China using trend analysis and partial correlation analysis.The results showed that the EVI of forests increased at a rate of 0.028/10a from 2001 to 2020,and the significantly improved area accounted for 39.63%of the total area.During the growing season,EVI was positively correlated with temperature,precipitation,global radiation and soil moisture,with soil moisture having the most significant effect,especially in the central and southern regions.The time-lag effect of EVI in response to various climatic factors varied among different regions.There was no time-lag effect in the response of EVI to temperature in all six regions.The lag in the response to global radiation was 3 months in all of them.In the northwestern region,the lag period of EVI response to precipitation was 3 months and 6 months in Southwest China.The lag period of EVI response to soil moisture was 6 months in East China.There was no time-lag effect in EVI response to precipitation and soil moisture in the rest of the regions.Overall,soil moisture was the main factor affecting vegetation changes in the growing season.