Data from: Correct calculation of CO2 efflux using a closed-chamber linked to a non-dispersive infrared gas analyzer

1. Improved understanding of the carbon (C) cycle is essential to model future climates and how this may feedback to affect greenhouse-gas fluxes. 2 .We summarize previous work quantifying respiration rates of organic substrates and briefly discuss how advances in technology, specifically the use of chambers linked to a non-dispersive infra-red gas analyzer (NDIR), can be applied to assess carbon dynamics from short-term field measurements. This technology hastens measurement and is relatively inexpensive, enabling researchers to increase replication and investigate temporal and spatial variation. 3. We describe the theory behind calculations of CO2 efflux released through organic substrates, when using a closed-chamber linked to a NDIR. These methods can in principle be extended to any chamber-based measurement of gas fluxes, including partially closed chambers as used for soil surface CO2, nitrous oxide or methane effluxes and stem CO2 respiration, although additional assumptions may apply. 4. We show that incorrect application of formulae in some earlier studies resulted in either under- or over-estimation of CO2 effluxes. Of the studies we reviewed measuring the respiration of woody debris, leaf-litter, or woody stems using closed chambers linked to a NDIR, only 22% (11 of 51) provided the equations used to calculate CO2 efflux, and 72% (8 of 11) of those provided contained basic errors. Using our data on the decomposition of woody debris as an example, we found that such mistakes resulted in anywhere from 8% underestimation to 22% overestimation of CO2 efflux. The errors varied among studies and hence may limit understanding of the factors affecting emissions of CO2 and our ability to incorporate this knowledge into global carbon models. 5. We provide formulae for the correct calculation of respiration rates in future studies using closed-chambers and thus provide a basis for comparative studies of factors affecting CO2 efflux from woody debris, leaf litter and other substrates. Ultimately this will contribute to improved parameterization of forest respiration.

1. 深化对碳（C）循环的认知，是构建未来气候模型、厘清该循环如何通过反馈过程影响温室气体通量的必要基础。2. 本研究梳理了此前针对有机底物呼吸速率量化的相关工作，并简要探讨了技术进步——尤其是结合非分散红外气体分析仪（non-dispersive infra-red gas analyzer, NDIR）的呼吸室技术——如何应用于通过短期野外测量评估碳动态变化。该技术可缩短测量时长且成本相对低廉，有助于研究人员提升实验重复次数，并探究碳动态的时间与空间变异特征。3. 本研究阐述了利用连接至NDIR的密闭式呼吸室，计算有机底物释放的CO₂通量的理论基础。原则上，该方法可拓展至任何基于呼吸室的气体通量测量场景，包括用于土壤表面CO₂、一氧化二氮或甲烷通量，以及茎秆CO₂呼吸测量的半密闭式呼吸室，但此时可能需要引入额外的假设条件。4. 本研究发现，部分早期研究中公式应用不当，会导致CO₂通量的计算结果出现低估或高估的情况。在本研究梳理的、利用连接NDIR的密闭式呼吸室测量木质残体、地表枯落物或木质茎秆呼吸的相关文献中，仅22%（51篇中的11篇）给出了用于计算CO₂通量的公式，而在这11篇提供公式的文献中，又有72%（8篇）存在基础性错误。以本研究获取的木质残体分解数据为例，这类错误会导致CO₂通量的计算结果出现8%的低估至22%的高估不等的偏差。不同研究中的错误程度存在差异，这可能会限制学界对影响CO₂排放的各类因素的认知，也会削弱我们将相关认知整合至全球碳循环模型中的能力。5. 本研究提供了未来研究中利用密闭式呼吸室正确计算呼吸速率的公式，为开展针对木质残体、地表枯落物及其他有机底物的CO₂通量影响因素的对比研究奠定了基础。最终，本研究将有助于完善森林呼吸作用的模型参数化工作。