Lagged effects regulate the inter-annual variability of the tropical carbon balance
Lagged effects regulate the inter-annual variability of the tropical carbon balance
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DOI：
10.5194/bg-17-6393-2020
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发表时间：
2020-12-17
期刊：
影响因子：
4.9
通讯作者：
Schimel, David S.
中科院分区：
文献类型：
--
作者：
Bloom, A. Anthony;Bowman, Kevin W.;Schimel, David S.
热带陆地碳平衡的年际变化是全球大气CO2增长率的主要组成部分。目前，控制热带生态系统碳净平衡过程的跨年度时间尺度的定量知识的缺乏，抑制了陆地-大气碳交换的准确理解和预测。特别是，生态系统C通量的相对贡献的不确定性，可归因于并发强迫异常（并发效应）和那些可归因于过去的现象（滞后效应）的持续影响，扼杀了努力，明确了解热带生态系统的气候变率的综合敏感性。在这里，我们提出了一个概念框架-适用于任何陆地生物圈模型的原则-明确量化净生物圈交换（NBE）的异常引起的并发变化和气候引起的滞后变化陆地生态系统C状态（NBE = NBECON + NBELAG）的总和。我们将此框架应用于2001-2015年热带C平衡的观测约束分析：我们使用数据模型集成方法，（CARBon数据库-模型框架-CARDASTM）合并卫星检索的陆地表面C观测（叶面积、生物量、太阳诱导荧光），土壤碳清单数据和基于卫星的大气反演估计的CO2和CO通量，以产生2001- 2015年热带C循环我们发现，在整个2001-2015年期间，同期和滞后效应的年际变化对2001-2015年热带NBE的年际变化有很大的贡献（NBECON IAV =总NBE IAV的80%，r = 0.76; NBELAG IAV = NBE IAV的64%，r = 0.61），并且NBELAG IAV的显著性在潮湿和干燥的热带生态系统中都持续存在。整个热带地区NBE滞后效应变化的幅度很大程度上归因于净初级生产力的滞后效应（NPP; NPPLAG IAV是NBELAG IAV的113%，r =-0.93，p值< 0.05），这是由于NPP依赖于叶片C和植物有效H2O状态的年际变化而出现的。我们的结论是，并发和滞后的影响需要明确和联合解决检索的过程中，调节现在和未来的轨迹陆地碳汇的准确理解。
Inter-annual variations in the tropical land carbon (C) balance are a dominant component of the global atmospheric CO2 growth rate. Currently, the lack of quantitative knowledge on processes controlling net tropical ecosystem C balance on inter-annual timescales inhibits accurate understanding and projections of land-atmosphere C exchanges. In particular, uncertainty on the relative contribution of ecosystem C fluxes attributable to concurrent forcing anomalies (concurrent effects) and those attributable to the continuing influence of past phenomena (lagged effects) stifles efforts to explicitly understand the integrated sensitivity of a tropical ecosystem to climatic variability. Here we present a conceptual framework - applicable in principle to any land biosphere model - to explicitly quantify net biospheric exchange (NBE) as the sum of anomaly-induced concurrent changes and climatology-induced lagged changes to terrestrial ecosystem C states (NBE = NBECON + NBELAG). We apply this framework to an observation-constrained analysis of the 2001-2015 tropical C balance: we use a data-model integration approach (CARbon DAta-MOdel fraMe-work - CARDAMOM) to merge satellite-retrieved landsurface C observations (leaf area, biomass, solar-induced fluorescence), soil C inventory data and satellite-based atmospheric inversion estimates of CO2 and CO fluxes to produce a data-constrained analysis of the 2001-2015 tropical C cycle. We find that the inter-annual variability of both concurrent and lagged effects substantially contributes to the 2001-2015 NBE inter-annual variability throughout 20012015 across the tropics (NBECON IAV = 80% of total NBE IAV, r = 0.76; NBELAG IAV = 64% of NBE IAV, r = 0.61), and the prominence of NBELAG IAV persists across both wet and dry tropical ecosystems. The magnitude of lagged effect variations on NBE across the tropics is largely attributable to lagged effects on net primary productivity (NPP; NPPLAG IAV 113% of NBELAG IAV, r = -0.93, p value < 0.05), which emerge due to the dependence of NPP on inter-annual variations in foliar C and plant-available H2O states. We conclude that concurrent and lagged effects need to be explicitly and jointly resolved to retrieve an accurate understanding of the processes regulating the present-day and future trajectory of the terrestrial land C sink.