1982—2015年中国温带地区夏季植被长势对生长季结束日期的影响

Effect of summer vegetation growth on the end of growing season in temperate regions in china from 1982 to 2015

基于1982—2015年GIMMS NDVI3g数据,利用累计NDVI的Logistic曲线曲率极值法识别中国温带生长季结束日期(End of Growing Season,EOS),并在空间上及不同植被类型上分析了夏季植被长势对生长季结束日期的影响。结果表明:研究期间,中国温带地区的夏季平均NDVI值主要分布在0.05~0.91之间,生长季结束日期主要集中在第231~313 d之间。在空间上,夏季NDVI与生长季结束日期呈负相关的区域占总面积的64.9%,显著负相关达20.7%,主要分布在新疆天山以南地区、青藏高原地区及内蒙古地区;而呈正相关关系的面积占全区35.1%,主要分布在研究区的东北部和东南部、新疆天山以北地区及青藏高原中部少数地区。从植被类型上看,森林植被类型(寒温带针叶林、暖温带落叶阔叶林、混交林)的夏季NDVI与生长季结束日期呈正相关,而在温带草原、青藏高原高寒植被、温带荒漠上与生长季结束日期呈负相关,这表明在干旱的生态系统类型上(温带草原、青藏高原高寒植被、温带荒漠),夏季植被长势旺盛导致生长季结束日期提前,而夏季植被的退化会推迟生长季结束日期。同时,气象因子作为植被生长发育的重要环境因子对生长季结束日期的变化起到重要作用。

Based on the GIMMS NDVI3g data from 1982 to 2015,the Logistic curve maximum curvature method of the cumulative normalized difference vegetation index(NDVI)was used to identify the end of growing season(EOS)in China's temperate region,and the influence of summer vegetation growth on the end of growing season was analyzed spatially in different vegetation types.The results showed that during the study period,the average summer NDVI value was mainly distributed between 0.05-0.91,and the end of growing season was mainly concentrated between the 231-313 days.In terms of space,the areas that summer NDVI negative correlated to the end of growing season accounted for 64.9%of the total area,and the significant negative correlation reached 20.7%,mainly distributed in the south of Tianshan Mountains in Xinjiang,Qinghai-Tibet Plateau and Inner Mongolia;however,the area with a positive correlation accounted for 35.1%of the entire region,mainly distributed in the northeast and southeast of the study area,the area north of Tianshan Mountains in Xinjiang,and a few areas in the middle of the Qinghai-Tibet Plateau.From the perspective of vegetation types,the summer NDVI of forest vegetation types(cold-temperate needle leaf forest,warm-temperate deciduous broadleaf forest,mixed needle-leaf and broadleaf forests)were positively correlated with the end of growing season,while in temperate grasslands,alpine vegetation on the Qinghai-Tibet Plateau,and temperate deserts,were negatively correlated with the end date of the growing season,which indicates that in arid ecosystem types,the vigorous growth in summer leaded to an earlier end of the growing season,while the degradation of summer plants postponed the end of the growing season.In addition,as an important environmental factor of vegetation growth and development,meteorological factors play an important role in the change of the end date of the growing season.