北半球中高纬度地区近30年植被春季物候温度敏感性

Temperature sensitivity of vegetation phenology in spring in mid-to high-latitude regions of Northern Hemisphere during the recent three decades

北半球气候变暖导致植被春季物候开始日期显著提前,温度对春季物候的促进作用是一个过程事件而非瞬时事件,且存在空间差异。该研究在以前研究的基础上,进一步分析温度对植被物候的作用方式,并探讨春季物候温度敏感性的空间特征及影响因素。利用GIMMS3g卫星植被指数产品,采用5种方法提取1982–2009年植被春季物候,并结合格网气象数据计算植被春季物候的温度敏感性,着重分析自然植被春季物候温度敏感性与环境因素的关系。结果表明,温度是北半球植被春季物候的主要制约因素,54%的像元显示温度最大效应发生在物候开始当月和之前一个月。温度主导的春季物候的像元中,91.3%的像元指示早春温度对物候开始的促进作用。植被春季物候的温度敏感性存在空间异质性,随着区域环境因素的不同,年际温度标准差、累积降水量和辐射对植被春季物候温度敏感性都具有各自或协同的调控作用。

Aims Under the current global warming,there are abundant evidence that the phenological events of vegetation in spring have advanced.Advancement of the phenological events in Northern Hemisphere under a gradual warming is considered a process of acclimation rather than an instantaneous feedback.Moreover,the occurrence of spring phenological advancement also varies across ecoregions.Following up on our previous studies,here we aim to determine the temproal scale that temperature has the most influential effect on changes in spring phenology.We further explore how the local spring temperature affects the temperature sensitivity of the spring phenology and the underlying mechanism.Methods We extracted the dates for spring phenological events by five different methods derived from the GIMMS3g normalized difference vegetation index dataset during 1982–2009.We also employed gridded climatic datasets to calculate the temperature sensitivity of the spring phenology of vegetation,and analyzed the relationship between the temperature sensitivity of phenological events of natural vegetation and environmental variables.Important findings The spring phenological events of vegetation were mainly regulated by the early spring temperature over the mid-to high-latitude regions in the Northern Hemisphere.Specifically,we found that the maximum temperature in the month of the green-up onset or in the preceding month played the dominant role in affecting the shifts in spring phenology over 54%of the pixels for the study regions;over 91.3%of the pixels displayed phenological shifts by early spring temperature.Interestingly,across the study regions,the standard deviation in interannual temperature,accumulative precipitation and short-wave radiation contrasted in their effects,and differentially or synergistically regulated the temperature sensitivity of spring vegetation phenology.