雅砻江流域生长季植被时空变化特征及对气象因子的响应分析

在全球气候变化背景下,开展植被变化对气象因子的响应研究对流域生态环境保护和水土资源合理利用具有重要的现实意义.以雅砻江流域为研究区,基于1982—2015年GIMMS NDVI数据,首先采用多种数理统计方法揭示生长季NDVI的时空变化特征,基于滞后相关系数法分析NDVI对气象因子的时滞效应,在此基础上建立各像元NDVI...

Analysis of Vegetation Spatiotemporal Variation Characteristics and Response to Meteorological Factors in the Growing Season in Yalong River Basin

In the context of global climate change,conducting research on the response of vegetation changes to meteorological factors is important and practical for the protection of the watershed ecological environment and the rational use of water and soil resources.Based on the GIMMS NDVI data from 1982 to 2015,this paper selects Yalong River Basin as the research area.First,a variety of mathematical statistics are used to reveal the spatiotemporal characteristics of NDVI in the growing season,and the time lag effect of NDVI on meteorological factors is analyzed based on the lag correlation coefficient method.On this basis,the principal component regression equation of each pixel’s NDVI and meteorological factors is established,and the main meteorological factors that affect the changes of NDVI and their contributions are analyzed,and then the characteristics of NDVI’s response to various meteorological factors are revealed.The results showed that:NDVI in Yalong River Basin showed a unimodal change during the year.The peak appeared in August.The interannual change of NDVI in the growing season showed an insignificant decreasing trend.NDVI of the watershed gradually decreased from downstream to upstream.The vegetation degradation area accounted for 30%,and the improvement area accounted for 24.28%.The middle reaches of the vegetation improvement and degradation area accounted for the largest proportion.In terms of changes in vegetation types,the improvement of coniferous forests accounted for a relatively large proportion.The degradation of shrubs and meadows is more serious.The controlling meteorological factors that led to the change of the watershed vegetation were precipitation and temperature,and their contributions to the vegetation change were 27.68%and 26.31%,respectively.The vegetation change in the upper reaches and north midstream was mainly affected by meteorological factors,and the vegetation change in the south midstream and lower reaches was jointly affected by meteorological factors and other factors(such as human activities).There were significant differences in the main control meteorological factors of NDVI changes in each pixel.Precipitation,average temperature and relative humidity were the controlling meteorological factors of vegetation changes in the upper and middle reaches,while precipitation and sunshine hours were the controlling meteorological factors of downstream vegetation changes.The response of the vegetation in the watershed to various meteorological factors had a certain time lag effect,and the ranking of the corresponding area for different factors was:average wind speed>precipitation>sunshine hours>average temperature>relative humidity.The response of the vegetation in the middle and upper reaches to the precipitation,average temperature and relative humidity was mainly in the current month and one month later;the response of the vegetation in the lower reaches to controlling meteorological factors was mainly one month and three months later.The response to the sunshine hours was mainly in the current month.