Dissertation Research: Linking microbial ecophysiology to soil organic matter abundance and stabilization

陆地生态系统依赖土壤有机质（SOM）维持农业生产力和其他重要的生态系统服务，但全球SOM库存受到环境变化的威胁。目前，减轻SOM损失的能力受到我们对SOM形成和长期持续性调节过程的理解的限制。近年来，SOM形成和持久性的新概念已经出现，表明SOM在很大程度上来自土壤微生物。与强调复杂的植物源化合物在SOM形成中的重要性的旧概念形成鲜明对比，如果更好地理解机制，对微生物过程的新强调可能会大大改善SOM管理。具体而言，有相对较少的了解微生物的生理特性，调节微生物的生产和微生物产品在不同的土壤类型的命运。为了解决这一知识差距，本研究的主要目标是将微生物生理特性与SOM的形成和持久性联系起来。这一目标将满足使用长期的实验室研究，以跟踪新形成的SOM来自不同类型的土壤中的微生物过程。土壤的粘土矿物和来自植物的碳输入各不相同，因此，将选择不同的微生物群落和生理特征，这可能会导致新形成的SOM的长期稳定性的差异。在整个实验过程中，将测量微生物的生理特性，可以连接到生物量合成，SOM形成率，SOM化学，微生物生物多样性，和SOM的持久性。这项工作的结果将导致改善目前的模型SOM的形成和稳定，并将表征微生物生理，碳输入质量和土壤环境之间的重要关系。这项研究将为微生物生态学、土壤和生态系统科学做出根本性贡献，并可能改变我们如何减轻土地利用转换和气候变化对SOM损失的不利影响。具体来说，这项研究可以鼓励新的方法，土地利用保护，恢复和农业管理，强调通过管理微生物生物量生产的SOM的间接建设。

Terrestrial ecosystems depend on soil organic matter (SOM) for sustaining agricultural productivity and other vital ecosystem services, yet global SOM stocks are threatened by environmental change. Currently, the ability to mitigate SOM losses is limited by our understanding of the processes regulating SOM formation and long-term persistence. In recent years, new concepts of SOM formation and persistence have emerged suggesting that SOM is largely derived from soil microbes. Contrasting sharply with older concepts that emphasize the importance of complex plant-derived compounds in SOM formation, the new emphasis on microbial processes might dramatically improve SOM management if only the mechanisms were better understood. Specifically, there is relatively little known about the microbial physiological traits that regulate microbial production and the fate of microbial products in different soil types. To address this knowledge gap, the broad objective of this research is to link microbial physiological traits to SOM formation and persistence. This objective will be met using a long-term laboratory study to track newly formed SOM derived from microbial processes in different soil types. The soils vary in their clay mineralogy and carbon inputs from plants and, as a result, will select for different microbial communities and physiological traits, which together will presumably lead to differences in the long-term stability of the newly formed SOM. Throughout the experiment, measurements will be made of microbial physiological traits that can be linked to biomass synthesis, rates of SOM formation, SOM chemistry, microbial biodiversity, and SOM persistence.Results from this work will lead to improvements in current models of SOM formation and stabilization and will characterize the important relationships among microbial physiology, carbon input quality, and the soil environment. This study will make fundamental contributions to microbial ecology and soil and ecosystem science and could change how we mitigate the adverse effects of land-use conversion and climate change on SOM losses. Specifically, this research could encourage new approaches for land-use conservation, restoration, and agricultural management that emphasize the indirect building of SOM by managing microbial biomass production.