植被生长峰值期(Peak of season,POS)是植被最重要的物候指标之一.本文基于GIMMS NDVI3g(1982-2015年)和MODIS NDVI(2001-2021年)数据建立两者之间的线性回归模型,研究了蒙古高原植被POS时空变化特征及其对气候变化的响应.结果表明,1982-2021年蒙古高原植被POS主要出现在第188～228天,即每年夏季6-8月,整体呈自西南向东北和自南向北逐渐提前的空间分布特征.除戈壁荒漠地区外,其余类型植被POS年际波动基本在10 d以内,年际变化较稳定.过去40 a间,研究区植被POS未出现显著的变化,变化介于-0.15～0.15 d/a.各植被类型POS变化趋势均不明显.从蒙古高原植被POS对气候的响应特征来看,季前3～5个月的降水量是影响研究区植被POS的主控因子,降水量的增加主要使植被POS呈推迟趋势,这种趋势在草地植被尤为显著,说明降水量的增加有利于草地植被在更长的时间内保持生长,致使POS推迟.在相对湿润和低温的森林、高寒草地和草甸草原等区域,降水量的增加使植被POS提前.气温和太阳辐射对研究区大部分区域POS的影响没有降水量强烈,在蒙古高原北部POS与温度之间呈负相关.在蒙古高原东北部地区太阳辐射的增加将POS推迟,而在中部草地将POS提前.
Spatio-temporal dynamics of vegetation peak growth timing and its responses to climate change on the Mongolian Plateau
Based on the data of GIMMS NDVI3g(1982-2015)and MODIS NDVI(2001-2021),we apply two sets of overlapping years of data(2001-2015),using the data from 2001 to 2013 as the modeling sample and the data from 2014 to 2015 as the validation sample.This article establishes a linear regression model between the two,ex-tends the research time to 2021,and studies the spatio-temporal variations of vegetation POS on the Mongolian Plateau and its responses to climate change.Results showed that the mean vegetation POS on the Mongolian Plateau mainly ranged between 188 and 228(day of year,DOY)from 1982 to 2021,that corresponded to the days between June and August.Spatially,vegetation POS was gradually advanced from southwest to northeast in Inner Mongolia of China and from south to north in Mongolia.And as the altitude increases,the appearance time of POS gradually advances,especially in areas above 1 300 m alititude.Except Gobi desert,the standard variation(SD)of POS for other vegetation types fluctuated within 10 days.In the past 40 years,there was no significant trend in POS on the study area,which fluctuated generally between-0.15～0.15 d/a.From the re-sponses of vegetation POS to climate factors on the Mongolian Plateau,the total precipitation of 3～5 months before the season was the main factor affecting the vegetation POS,and the increased precipitation mainly delayed the vegetation POS,especially for grasslands,indicating that the increase of precipitation is conducive to grassland to maintain growth for a longer period of time,leading to the postponement of POS.However,on the relatively humid and cold areas like forests,there was a negative correlation relationship between vegeta-tion POS and total precipitation.The impact of temperature and solar radiation on POS in most areas of the study area is not as strong as precipitation,and there is a negative correlation between POS and temperature in the northern Mongolian Plateau.In the northeast of Mongolian Plateau,the increase of solar radiation delayed POS,while in the central grassland,POS was advanced.
the peak growth of vegetationclimate changethe Mongolian Plateau
万方数据
维普
