植被物候的遥感提取及其影响因素研究进展

植被物候是反映植被动态的重要指标和气候变化对生态系统影响的重要感应器,它影响着地表反照率、粗糙度、蒸发散、CO₂通量以及人类生产活动。首先论述了基于遥感的植被物候提取方法和植被物候变化的影响因素两方面的研究进展,然后指出气候变化背景下植物物候研究存在的突出问题,包括遥感难以直接获取常绿植被叶片和冠层结构物候、尺度效应阻碍遥感产品与地面观测的匹配、气候要素(降水和日间、夜间温度等)和城市化对物候的影响及协同作用机制不清楚、缺少针对植被类型的物候产品和模型以及未将物候间滞后效应纳入考虑等。开展常绿植被物候指标的遥感提取方法及算法研制,探索气候变化、极端天气气候对物候的影响机制及未来预估,分析城市化、植被类型对物候的影响以及与气候变化的协同效应,建立综合考虑降水、滞后效应和尺度效应的群落尺度物候模型,是未来工作关注的重点。

Advances in Remote Sensing Extraction of Vegetation Phenology and Its Driving Factors

Phenology is considered as an important indicator for understanding the vegetation dynamics and the impact of climate change on ecosystem.It has significant influences on surface albedo,roughness,evapotranspiration,CO₂ flux,and human activities.This study presents the progress on the phenology extraction methods based on satellite,and the driving factors of vegetation phenology dynamics.The key weaknesses in our current understanding of vegetation phenology in the context of climate change are also raised,including the difficulty in estimating the phenology of evergreen vegetation based on remote sensing directly from the perspective of leaf and canopy structure,the low comparability between satellite products and ground-based measurements due to the scale effect,the unclear synergistic mechanisms between climate factors(rainfall and day/night temperature)and urbanization,the lack of phenological products and models for specific vegetation types,as well as the inconsideration of lag effect of phenology.So,it is important to focus on the following four aspects in future research:(1)the development of satellite phenology extraction methods for evergreen vegetation;(2)the research on the mechanisms and forecast of climate change and extreme weather on phenology;(3)the study of the impact of urbanization and vegetation types on phenology,together with their synergistic effects;(4)the establishment of phenological model at community scale which considers precipitation,lag effect and scale effect.