Rewetting of soil: Revisiting the origin of soil CO2 emissions
Rewetting of soil: Revisiting the origin of soil CO2 emissions
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DOI：
10.1016/j.soilbio.2020.107819
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发表时间：
2020-08-01
影响因子：
9.7
通讯作者：
Firestone, Mary K.
中科院分区：
文献类型：
--
作者：
Barnard, Romain L.;Blazewicz, Steven J.;Firestone, Mary K.
干土壤的湿润与微生物活动和矿化的爆发有关，这表现为土壤二氧化碳排放的脉冲，也就是长期以来所知的白桦树效应。在干旱和半干旱系统中，在延长的干旱期结束时，土壤重新湿润时的二氧化碳损失可能在总的碳(C)收支中占很大比例。微生物生物量是矿化碳的来源之一，30多年前就证明了这一点(Kieft等人，1987年)。本文介绍了自1987年发表在《土壤生物学与生物化学》上的那篇论文以来，该领域的进展情况，它对当前全球气候变化的关注意味着什么，以及未来研究的需要和潜在的重点。自1987年以来，许多研究都探讨了这种二氧化碳脉冲的来源，发现了多种可能的碳源，既涉及生物过程，也涉及非生物过程。我们认为，再湿事件(增量psi)的大小决定了底物阵列在再湿时对土壤二氧化碳脉冲的相对贡献。二氧化碳脉动的大小可能与土壤物理特性和部分由植物控制的有效碳库的大小有关。此外，在复湿时产生土壤二氧化碳脉冲的机制的相对贡献可能会被气候变化所改变。为了了解和预测土壤在复湿时二氧化碳脉动的大小，我们主张继续进行涉及土壤微生物生态学、土壤物理、土壤化学的跨学科研究，并加强对植物-土壤相互作用在控制土壤碳库对土壤二氧化碳脉动影响的重要性的整合和认识。
Rewetting dry soils is associated with a burst of microbial activity and mineralization, which manifests itself as a pulse in soil CO2 emissions, long-known as the Birch effect. In arid and semi-arid systems, soil CO2 losses upon rewetting at the end of extended dry periods can contribute a significant fraction to the overall carbon (C) budget. Microbial biomass is one of the sources of mineralized C, as was demonstrated over 30 years ago (Kieft et al., 1987). The present paper offers a perspective on how the field has progressed since the 1987 paper was published in Soil Biology & Biochemistry, what it means in terms of current concerns about global climate change, and the needs and potential emphases of future research. Many studies since 1987 have addressed the origin of this CO2 pulse, finding multiple possible C sources involving both biotic and abiotic processes. We propose that the magnitude of the rewetting event (Delta psi) determines the relative contribution from the array of substrates that contribute to the soil CO2 pulse upon rewetting. The magnitude of the CO2 pulse is likely related to soil physical characteristics and to the size of the available C pool, which is partly controlled by plants. Further, the relative contributions of the mechanisms generating soil CO2 pulses upon rewetting are likely to be modified by climate change. To understand and predict the magnitude of soil CO2 pulses upon rewetting, we advocate continued cross-disciplinary research involving soil microbial ecology, soil physics, soil chemistry, as well as increased integration and recognition of the importance of plant-soil interactions in controlling the soil C pools contributing to soil CO2 pulses.