Biological carbon stabilization and destabilization: peering into microbial hot spots to understand soil carbon turnover and terrestrial energy flows

生物碳稳定和不稳定：深入研究微生物热点以了解土壤碳周转和陆地能量流

• 批准号: RGPIN-2019-04158
• 负责人: Helgason, Bobbi
• 金额: $ 1.82万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=713461
• 关键词: Biological; carbon; stabilization; destabilization; peering

Burgeoning population, agricultural intensification and changing climate are threatening global food security. Understanding the amount, composition and stability of soil carbon (C) is needed to enhance soil fertility and agroecosystem sustainability and to establish a fair and transparent approach to evaluating sector contributions to climate change mitigation. Recently, great focus has been on storing or sequestering soil C. While this goal is critical to climate change mitigation, it is important to recognize that soil C not only needs to be stored, but also used to maintain ecosystem function. Plant photosynthate is the primary source of new C, and thus new energy, in agroecosystem soils. Formation of soil organic matter is mediated by microorganisms that utilize plant C during decomposition, releasing energy and nutrients. Understanding these microbial transformations is critical. Soil organic matter is at the heart of soil fertility and productivity. It holds C and nutrients that support plant growth, fuels biological processes, provides habitat for the biota responsible and buffers against short-term stresses (e.g. nutrient imbalance or drought). Hot-spots of microbial activity such as plant residue surfaces and microsites within soil aggregates have active populations up to twenty times higher than the bulk soil. Hot spots arise from abundant resource availability (e.g. C). They are temporally dynamic and difficult to study at relevant scales of time and space. Improved understanding of the roles of microbial taxa or community traits that perform decomposition is needed to optimize C cycling processes and for sustainable soil management. To better understand microbial dynamics of C-turnover in C-rich hot spots, the proposed research program will specifically examine how soil microorganisms act as agents of C flows through three projects which address separate, but related aspects of microbial ecology of soil C stabilization and destabilization: 1) a survey of relationships between thermodynamic efficiency of C use and microbial community composition in different agricultural soils, 2) use C-rich buried soils as a model system to identify indicator microorganisms and SOM biomarkers for C-stabilization in C-rich hot-spots, 3) profile microbial communities and C turnover in physical size fractions and aggregates of these C-rich buried soils to better understand the role of microhabitats as potential hot-spots of C stabilization. The interrelatedness of macronutrients nitrogen (N), phosphorus (P) and potassium (K) is acknowledged in soil fertilizer management. Explicit integration of C into resource management strategies has the potential to greatly enhance fertilizer use efficiency and to bolster critical functions of air and water filtration, climate change mitigation and food production. In other words, a shift toward a CNPK management frameworks will better support sustainable soil management and ultimately, food security.

迅速增长的人口、农业集约化和不断变化的气候正在威胁全球粮食安全。需要了解土壤碳（C）的数量、组成和稳定性，以提高土壤肥力和农业生态系统的可持续性，并建立一个公平和透明的方法来评估部门对减缓气候变化的贡献。最近，人们非常关注储存或隔离土壤C。虽然这一目标对减缓气候变化至关重要，但重要的是要认识到土壤碳不仅需要储存，而且还需要用于维持生态系统功能。植物光合产物是农业生态系统土壤中新碳的主要来源，因此也是新能量的主要来源。土壤有机质的形成是由微生物介导的，微生物在分解过程中利用植物C，释放能量和养分。了解这些微生物转化是至关重要的。土壤有机质是土壤肥力和生产力的核心。它含有碳和营养物质，支持植物生长，为生物过程提供燃料，为生物区系提供栖息地，并缓冲短期压力（例如营养失衡或干旱）。 微生物活动的热点，如植物残体表面和土壤团聚体中的微生物位点，其活性种群比散装土壤高出20倍。热点产生于丰富的资源可用性（例如C）。它们是时间动态的，难以在相关的时间和空间尺度上进行研究。需要更好地了解微生物类群或群落特征的作用，执行分解，优化碳循环过程和可持续的土壤管理。为了更好地了解富碳热点中碳周转的微生物动力学，拟议的研究计划将具体研究土壤微生物如何通过三个项目作为碳流的代理人，这些项目涉及土壤碳稳定和不稳定的微生物生态学的独立但相关的方面：1）不同农业土壤中碳利用热力学效率与微生物群落组成之间关系的调查，2）以富碳埋藏土壤为模型系统，研究富碳热点土壤中碳稳定化的指示微生物和有机质生物标志物; 3）研究富碳埋藏土壤中物理粒级和团聚体中的微生物群落和碳周转，以更好地了解微生境作为潜在碳稳定化热点的作用。 大量元素氮、磷、钾之间的相关性在土壤肥料管理中已得到公认。将C明确纳入资源管理战略有可能大大提高肥料的使用效率，并加强空气和水过滤、减缓气候变化和粮食生产的关键功能。换句话说，向CNPK管理框架的转变将更好地支持可持续的土壤管理，并最终支持粮食安全。