Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2022 Nov 25;849:157856. doi: 10.1016/j.scitotenv.2022.157856. Epub 2022 Aug 5.
Annual gross primary productivity (AGPP) of terrestrial ecosystems is the largest carbon flux component in ecosystems; however, it's unclear whether photosynthetic capacity or phenology dominates interannual variation of AGPP, and a better understanding of this could contribute to estimation of carbon sinks and their interactions with climate change. In this study, observed GPP data of 494 site-years from 39 eddy covariance sites in Northern Hemisphere were used to investigate mechanisms of interannual variation of AGPP. This study first decomposed AGPP into three seasonal dynamic attribute parameters (growing season length (CUP), maximum daily GPP (GPP), and the ratio of mean daily GPP to GPP (α)), and then decomposed AGPP into mean leaf area index (LAI) and annual photosynthetic capacity per leaf area (AGPP). Furthermore, GPP was decomposed into leaf area index of DOY (the day when GPP appeared) (LAI) and photosynthesis per leaf area of DOY (GPP). Relative contributions of parameters to AGPP and GPP were then calculated. Finally, environmental variables of DOY were extracted to analyze factors influencing interannual variation of GPP. Trends of AGPP in 39 ecosystems varied from -65.23 to 53.05 g C m yr, with the mean value of 6.32 g C m yr. Photosynthetic capacity (GPP and AGPP), not CUP or LAI, was the main factor dominating interannual variation of AGPP. GPP determined the interannual variation of GPP, and temperature, water, and radiation conditions of DOY affected the interannual variation of GPP. This study used the cascade relationship of "environmental variables-GPP-GPP-AGPP" to explain the mechanism of interannual variation of AGPP, which can provide new ideas for the AGPP estimation based on seasonal dynamic of GPP.
陆地生态系统的年总初级生产力 (AGPP) 是生态系统中最大的碳通量组成部分；然而，目前尚不清楚光合能力还是物候学主导着 AGPP 的年际变化，更好地了解这一点有助于估算碳汇及其与气候变化的相互作用。在本研究中，利用北半球 39 个涡度相关站点的 494 个站点年的观测 GPP 数据，研究了 AGPP 年际变化的机制。本研究首先将 AGPP 分解为三个季节性动态属性参数（生长季长度 (CUP)、最大日总初级生产力 (GPP) 和平均日 GPP 与 GPP 的比值 (α))，然后将 AGPP 分解为平均叶面积指数 (LAI) 和单位叶面积的年光合能力 (AGPP)。此外，将 GPP 分解为出现 GPP 的日期 (DOY) 的叶面积指数 (LAI) 和 DOY 的单位叶面积光合作用 (GPP)。然后计算参数对 AGPP 和 GPP 的相对贡献。最后，提取 DOY 的环境变量，分析影响 GPP 年际变化的因素。39 个生态系统的 AGPP 趋势从-65.23 到 53.05 g C m yr，平均值为 6.32 g C m yr。光合能力（GPP 和 AGPP）而不是 CUP 或 LAI，是主导 AGPP 年际变化的主要因素。GPP 决定了 GPP 的年际变化，而 DOY 的温度、水分和辐射条件影响了 GPP 的年际变化。本研究利用“环境变量-GPP-GPP-AGPP”的级联关系来解释 AGPP 年际变化的机制，这为基于 GPP 季节性动态的 AGPP 估算提供了新的思路。
