基于光谱观测的亚热带人工针叶林叶绿素荧光与光合作用能力关系的研究

By measuring the chlorophyll fluorescence parameters and photosynthetic rate (CO2 assimilation rate) of China's subtropical planted coniferous forest in Jiangxi province, as well as using multi-source and multi-scale observation data (eddy covariance flux, radiation, spectral reflectance, LAI), we will explore the internal relations of chlorophyll fluorescence and GPP and light use efficiency (LUE) so that we can investigate the ability of the chlorophyll fluorescence reflecting vegetation photosynthetic variation in response to the environmental stress. Such theoretical and technical support is important for improving the accuracy of GPP estimation by remote sensing in regional scale. ..In this study, we hope to establish the relationship between sun-induced chlorophyll fluorescence (SIF) and GPP at canopy scale, evaluating how much the SIF and PRI can be the proxy of GPP and LUE of the planted coniferous forest, respectively. Based on the SIF signal and PRI, the LUE model will be optimized, which we try to improve the simulation accuracy of GPP of planted coniferous forest. Furthermore, the effects of vegetation structure parameters and environmental factors on the relationship between GPP and SIF can be better understood...Therefore, with a combination of satellite remote sensing and near-ground carbon flux observation technology, we can continuously observe the changes of ecosystem GPP at regional level, which helps to better understand the relationship between the photosynthesis and optical signal as well as the interaction of ecosystem and climate system, promoting the application of using remote sensing data for carbon flux upscaling. The thorough discussion of photosynthesis response to water or temperature stress in the planted coniferous forest helps to evaluate the recovery of the ecosystem function. Also, we will be fully aware of the contribution of carbon sequestration potential slowing down the greenhouse effect of southern planted forest in China.

本研究以位于江西省的千烟洲通量站亚热带人工针叶林为研究对象，开展长期连续的植被冠层光谱观测，通过测定人工林叶绿素荧光参数与光合作用速率(CO2同化速率)，利用多源观测数据（涡度碳水能量通量、辐射、光谱观测、LAI等），探讨荧光信息反映植被光合作用对环境胁迫因子的短时间响应的能力；建立冠层尺度日光诱导叶绿素荧光(SIF)与GPP的定量关系，评价SIF信息与PRI分别作为人工针叶林GPP和LUE指标器的作用；基于SIF信息和PRI改进光能利用率模型，提高模型对人工针叶林生态系统GPP的模拟精度，阐明植被结构参数和环境要素对SIF与GPP关系的影响。开展亚热带人工针叶林叶绿素荧光、光合作用和植被结构关键参数的光谱观测研究，将有助于揭示植被叶绿素荧光、生理生化指数与GPP、光能利用效率的内在联系，揭示生态系统真实光合作用的动态变化特征，为开展区域尺度GPP遥感估算提供重要的理论和技术支撑。

本研究以亚热带常绿林为研究对象，开展叶片叶绿素荧光参数野外观测，探讨叶片荧光参数的动态变化特征以及其受环境因子的影响；搭建植被冠层高光谱观测系统，基于长期连续的植被冠层高光谱观测，反演日光诱导叶绿素荧光，提取光化学植被指数、叶绿素荧光指数以及传统遥感植被指数，结合涡度碳水通量观测提取总初级生产力GPP和光能利用率LUE，建立了冠层尺度SIF与GPP、PRI与LUE的定量关系，评价了SIF与PRI分别作为亚热带常绿林GPP和LUE指标器的作用，并阐明了环境要素和植被结构对其关系的影响；基于光谱观测数据提取的多种遥感指数，借助光合有效辐射因子和多元回归模型，提高了对亚热带常绿林生态系统GPP的模拟精度。本研究进行的亚热带常绿林叶绿素荧光和遥感植被指数的光谱观测研究，有助于阐明常绿林植被叶绿素荧光、生理生化指数与光合作用的内在联系，揭示亚热带常绿林光合作用的动态变化特征，并为开展区域尺度GPP遥感估算提供重要的理论和技术支撑。