Boreal soil carbon: the stable, the labile, and the unknown

北方土壤碳：稳定、不稳定和未知

• 批准号: RGPIN-2014-04693
• 负责人: Quideau, Sylvie
• 金额: $ 3.79万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=662794
• 关键词: Boreal; soil; carbon; stable; labile

Boreal forest soils are the single largest terrestrial carbon storehouse in the world. Consequently, changes in boreal carbon stocks and fluxes could significantly affect the global carbon cycle. These northern, high-latitude soils are also highly susceptible to global warming, and in the coming century are expected to face large increases in average temperatures, altered freeze-thaw patterns, and transformative vegetation shifts. The carbon contained in boreal soils is a complex network of interconnected pools whose stability may be controlled by different mechanisms. As such, it has been challenging to predict the response of boreal soil carbon to environmental changes. **My long-term research objective is to quantify how the underlying environmental factors control organic matter accumulation and distribution in soils. With this proposed research program, I plan to clarify how interactions between the soil geological material and vegetation may ultimately determine the response of boreal soil carbon to climatic changes. I will address this challenge by:*1. Quantifying the sources, formation pathways, and stability of two carbon pools (subsurface and forest floor) that turn over on a decadal time scale; *2. Investigating how carbon fluxes through labile (biological and rhizosphere) carbon pools may be altered by environmental changes, and how this may affect subsequent carbon accumulation pathways and stability.**I will be training three PhD and two Msc students, as well as several undergraduate research assistants. Student projects will be independent yet interlinked. The focus of these projects is to understand how various environmental factors, including overall warming, changes in freeze-thaw cycles, and vegetation shifts, will affect the following four boreal carbon stores: *1. Subsurface soil carbon-- We will investigate how soil geological material may control the source and stability of carbon present at depth;*2. Forest floor carbon-- We will focus on the carbon present within the deeper, humified organic matter layer, and investigate the possibility that this carbon may, in some cases, be more stable than deep mineral carbon;*3. Biological carbon-- We will look at how vegetation changes affect carbon fluxes through soil biological communities in representative boreal forests;*4. Rhizosphere carbon-- We will examine how the rhizosphere (zone of root influence) affects the partitioning of microbial carbon fluxes between catabolic and anabolic processes.**A variety of boreal forests from across Canada will be included in this program. This will allow for characterization of soil organic matter from wide ranges of geological materials, forest stand types, and climate. The program will combine a sound pedological field approach, isotope labelling experiments in controlled-environment chambers, and state-of-the-art analytical protocols. The result will be an unprecedented characterization of organic matter transformation pathways, which will fundamentally advance our understanding of carbon accumulation and stability in boreal soils. Overall, this research program will establish the foundational scientific knowledge required to improve prediction of boreal soil carbon response to climate change. This will, in turn, inform management and adaptation strategies that are tailor-made for sustaining boreal forest ecosystems.

北方森林土壤是世界上最大的陆地碳库。因此，北方碳储量和通量的变化可能会对全球碳循环产生重大影响。这些北方高纬度的土壤也非常容易受到全球变暖的影响，在未来的世纪，预计将面临平均气温大幅上升，冻融模式改变，植被变化。北方土壤中所含的碳是一个复杂的相互连接的碳库网络，其稳定性可能受到不同机制的控制。因此，预测北方土壤碳对环境变化的响应具有挑战性。* * 我的长期研究目标是量化潜在的环境因素如何控制土壤中有机质的积累和分布。 通过这项研究计划，我计划阐明土壤地质物质和植被之间的相互作用如何最终决定北方土壤碳对气候变化的反应。我将通过以下方式应对这一挑战：* 1。量化在十年时间尺度上翻转的两个碳库（地下和森林地面）的来源，形成途径和稳定性;* 2。调查通过不稳定（生物和根际）碳库的碳通量如何被环境变化改变，以及这如何影响随后的碳积累途径和稳定性。我将培训三名博士生和两名硕士生，以及几名本科生研究助理。 学生的项目将是独立的，但相互关联。这些项目的重点是了解各种环境因素，包括整体变暖，冻融循环的变化和植被转移，将如何影响以下四个北方碳储量：* 1.地下土壤碳-我们将研究土壤地质物质如何控制深度碳的来源和稳定性;* 2.森林地面碳-我们将关注存在于更深的腐殖化有机质层中的碳，并研究这种碳在某些情况下可能比深层矿物碳更稳定的可能性;* 3。生物碳--我们将研究植被变化如何通过代表性的北方森林中的土壤生物群落影响碳通量;根际碳-我们将研究根际（根影响区）如何影响微生物碳通量在分解代谢和合成代谢过程之间的分配。来自加拿大各地的各种北方森林将包括在这个计划中。这将允许从广泛的地质材料、林分类型和气候中表征土壤有机质。该计划将结合联合收割机健全的土壤学领域的方法，在受控环境室的同位素标记实验，和国家的最先进的分析协议。其结果将是有机物转化途径的前所未有的表征，这将从根本上推进我们对北方土壤中碳积累和稳定性的理解。总的来说，这项研究计划将建立所需的基础科学知识，以提高北方土壤碳对气候变化的响应预测。这将反过来为专门为维持北方森林生态系统而制定的管理和适应战略提供信息。