植被物候是监测陆地生态系统和全球气候变化的重要生物指标.基于经典遥感植被指数的陆表物候监测在不同植被类型的精确分析方面存在较大挑战,日光诱导叶绿素荧光(SIF)可以直接反映植被实际光合作用的动态变化,能够更精确地刻画出植被的年际变异.本研究基于2001～2020年GOSIF数据集,通过D-L拟合函数和动态阈值法提取东北地区植被物候参数,结合一元线性回归分析、稳定性和持续性分析,在多时空尺度下分析2001～2020年东北地区植被物候的时空演变特征,并探讨植被物候对气候变化的响应机制.结果表明:①植被生长季开始(Start of Season,SOS)、结束(End of Season,EOS)、生长季长度(Length of Season,LOS)和生长峰值(Position of Peak,POP)整体上分别呈现出提前、推迟、延长和提前趋势;②草丛SOS提前、EOS推迟趋势较为显著,针叶林EOS提前趋势显著;SOS提前、EOS推迟导致LOS延长,除针叶林外,所有植被类型LOS均呈现出延长趋势;除草丛和草原外,其余植被类型POP均呈提前趋势;③20年来植被SOS、EOS、LOS和POP变化较为稳定,变异系数均小于0.1;④大部分区域植被SOS、EOS、LOS和POP的H值介于0.35～0.5之间,说明其变化趋势与过去相反,将呈现微弱延迟、提前、缩短和延长的趋势;⑤整体上气温和降水对植被物候的影响机制相反,即气温升高(降水增加)导致SOS和POP提前(推迟)、EOS推迟(提前)以及LOS延长(缩短);相对湿度与植被物候参数均呈负相关关系.本研究结果有助于理解植被进行光合作用的时空格局变化及对气候变化的响应机制,也为东北地区生态环境的评估和管理提供参考.
Spatiotemporal Characteristics of Vegetation Phenology in Northeast China based on Solar-induced Chlorophyll Fluorescence and Response to Climate
Vegetation phenology is an important biological indicator for monitoring terrestrial ecosystems and global climate change.The monitoring of land surface phenology based on classical remote sensing vegetation in-dices is more challenging in terms of accurate analysis of different vegetation types.Solar-Induced Chlorophyll Fluorescence(SIF)is more sensitive to the seasonal dynamics of vegetation and can more accurately portray the interannual variability of vegetation.Based on the 2001～2020 GOSIF dataset,this study extracted the vege-tation phenology parameters in Northeast China by D-L fitting function and dynamic threshold method,com-bined with unitary linear regression analysis,stability and sustainability analysis,this study analyzed the spatio-temporal evolution characteristics,stability and sustainability of vegetation phenology in Northeast China from 2001 to 2020 at multiple spatiotemporal scales,and explored the response mechanism of vegetation phenology to climate change.The results showed that SOS,EOS,LOS,and POP showed advanced,delayed,pro-longed and advanced,respectively.The trend of SOS advance and EOS delay in grassland was significant,and EOS of coniferous forests was advanced.The advance of SOS and the delay of EOS led to the prolongation of LOS.Except for coniferous forest,all vegetation types showed an extended trend of LOS.All vegetation types POP showed an advance trend,except for grassland and steppe.The changes of SOS,EOS,LOS and POP were relatively stable in the past 20 years,and the coefficients of variation were all less than 0.1.The H values of SOS,EOS,LOS and POP in most regions ranged between 0.35 and 0.5,indicating that the trend was oppo-site to the past and would show a slight trend of delay,advance,shortening and delay.Overall,the influence mechanism of temperature and precipitation was opposite on vegetation phenology,that is,higher temperature(increased precipitation)led to advance(delay)of SOS and POP,delay(advance)of EOS,and lengthen(shorten)of LOS.There was a negative correlation between relative humidity and vegetation phenological pa-rameters.The results of this study help to understand the spatiotemporal pattern changes of photosynthesis in vegetation and the response mechanism to climate change,and also provide reference for the assessment and management of ecological environment in Northeast China.
Northeast ChinaVegetation phenologySolar-Induced Chlorophyll Fluorescence(SIF)Climate changeGrowing season
NETL
NSTL
万方数据
维普
