Clarifying the evidence for microbial‐ and plant‐derived soil organic matter, and the path toward a more quantitative understanding
Clarifying the evidence for microbial‐ and plant‐derived soil organic matter, and the path toward a more quantitative understanding
复制标题
DOI：
10.1111/gcb.16413
复制
发表时间：
2022-08
影响因子：
11.6
通讯作者：
E. Whalen;A. Stuart Grandy;Noah W. Sokol;M. Keiluweit;J. Ernakovich;Richard G. Smith;S. Frey
中科院分区：
文献类型：
--
作者：
E. Whalen;A. Stuart Grandy;Noah W. Sokol;M. Keiluweit;J. Ernakovich;Richard G. Smith;S. Frey
预测和缓解全球变化下土壤碳 (C) 储量的变化需要对调节土壤有机质 (SOM) 形成和持久性的因素有一致的了解，包括了解 SOM 的直接来源（植物与微生物）。近年来，SOM 形成的概念模型强调了微生物来源的有机物质输入的首要性，提出微生物生理特性（例如生长效率）是 SOM 数量的主要控制因素。然而，最近的定量研究对这一观点提出了挑战，表明植物对 SOM 的直接贡献比目前这一范式所认识到的要大。在这篇综述中，我们试图通过强调植物来源的 SOM 与微生物来源的 SOM 估计之间的差异可能部分源于方法学的限制来调和这些观点。我们表明，用于估计植物与微生物对 SOM 贡献的所有主要方法都存在重大缺陷，突出了我们当前定量估计的不确定性。我们证明，微生物、植物根部以及植物凋落物细胞外分解产生的化合物的化学特征存在显着重叠，这给使用常见生物标志物解析植物和微生物衍生的 SOM 带来了不确定性，特别是在矿物相关有机物 (MAOM) 部分。尽管我们回顾的研究有助于更深入地了解微生物对 SOM 的贡献，但当前方法的局限性限制了定量估计。鉴于最近的进展，我们建议现在是重新评估长期存在的方法、明确其局限性并制定战略计划以改进植物和微生物来源的 SOM 定量的关键时刻。通过我们的综合，我们概述了未来研究植物和微生物途径 SOM 形成和稳定机制的关键问题和挑战。
Predicting and mitigating changes in soil carbon (C) stocks under global change requires a coherent understanding of the factors regulating soil organic matter (SOM) formation and persistence, including knowledge of the direct sources of SOM (plants vs. microbes). In recent years, conceptual models of SOM formation have emphasized the primacy of microbial‐derived organic matter inputs, proposing that microbial physiological traits (e.g., growth efficiency) are dominant controls on SOM quantity. However, recent quantitative studies have challenged this view, suggesting that plants make larger direct contributions to SOM than is currently recognized by this paradigm. In this review, we attempt to reconcile these perspectives by highlighting that variation across estimates of plant‐ versus microbial‐derived SOM may arise in part from methodological limitations. We show that all major methods used to estimate plant versus microbial contributions to SOM have substantial shortcomings, highlighting the uncertainty in our current quantitative estimates. We demonstrate that there is significant overlap in the chemical signatures of compounds produced by microbes, plant roots, and through the extracellular decomposition of plant litter, which introduces uncertainty into the use of common biomarkers for parsing plant‐ and microbial‐derived SOM, especially in the mineral‐associated organic matter (MAOM) fraction. Although the studies that we review have contributed to a deeper understanding of microbial contributions to SOM, limitations with current methods constrain quantitative estimates. In light of recent advances, we suggest that now is a critical time to re‐evaluate long‐standing methods, clearly define their limitations, and develop a strategic plan for improving the quantification of plant‐ and microbial‐derived SOM. From our synthesis, we outline key questions and challenges for future research on the mechanisms of SOM formation and stabilization from plant and microbial pathways.