The effect of disturbance on the biogeochemical cycling of carbon in northern forest soils

土壤有机质是陆地上最大的有机碳（OC）库，其分解导致每年约75 Pg碳（C）以二氧化碳（CO2）的形式释放到大气中。超过70%的这些排放量来自一个小池（总碳的1%）最近结合（<1年）的有机物，其余的排放量来自一个更稳定的土壤有机碳（SOC）池。这种稳定的SOC池分解较慢，因为它受到物理、化学和/或生物保护而不分解。虽然我们有一个合理的理解，如何小，快速循环的SOC池响应环境变化，我们的知识的稳定/不稳定的过程中更稳定的SOC池没有得到很好的发展。随着气候变化，预计北方森林的森林火灾将更加频繁，随着北方地区生长度日的增加，农业扩展的机会正在出现。与此同时，人们对使用生物质燃烧产生生物能的兴趣越来越大，生物质燃烧产生木灰，木灰是碱性的，可以用作土壤改良剂以提高场地生产力。火灾和土地管理，以及气候的变化，改变了土壤环境的物理，化学和生物，这可能会导致“稳定”碳库的变化。在接下来的五年里，我的研究计划将调查灰添加对SOC转化和传输的影响，具体目标是：1。定量的作用，钙，铁和铝，稳定的SOC在酸性北方土壤，2。评估pH和Ca增加以增强酸性土壤中矿物相关有机碳的稳定能力的潜力，以及3.确定添加的灰分的量是否影响SOC向土壤剖面更深处的转化和运输。满足我的计划的短期目标将有助于我的职业目标1。提高我们对环境变化对北方土壤有机碳生态地球化学循环的影响的认识。推进碳同位素和SOC分馏技术在地球化学研究中的应用。这些目标将通过并行学生主导的项目来实现。

Soil organic matter is the largest terrestrial reservoir of organic carbon (OC) and its decomposition is responsible for the annual release of an estimated 75 Pg carbon (C) into the atmosphere as carbon dioxide (CO2). Over 70% of these emissions are derived from a small pool (<1% of total C) of recently incorporated (<1 yr) organic matter, with the remaining emissions being derived from a more stable pool of soil organic carbon (SOC). This stable pool of SOC is slower to decompose because it is protected from decomposition physically, chemically and/or biologically. Though we have a reasonable understanding of how the small, fast cycling pool of SOC responds to environmental change, our knowledge of the process of stabilization/destabilization of the more stable pool of SOC is not as well developed. As climate changes, forest fires are expected to become more frequent in northern forests and opportunities for agricultural expansion are emerging with increases in growing degree days in northern regions. In tandem, there has been increasing interest in bioenergy generation using the combustion of biomass which generates wood ash that is alkaline and may be used as a soil amendment to improve site productivity. Fires and land management, alongside changes in climate, alter the soil environment physically, chemically, and biologically which may lead to changes in the pool(s) of "stable" carbon. Over the next five years my research program will investigate the effects of ash addition on the transformation and transport of SOC with the specific objectives of: 1. quantifying the role of Ca, alongside Fe and Al, on stabilization of SOC in acidic northern soils, 2. assessing the potential for increases in pH and Ca to enhance the stabilization capacity of mineral associated organic carbon in acidic soils, and 3. determining if the amount of ash added affects the transformation and transport of SOC deeper into the soil profile. Meeting the short-term objectives of my program will contribute to my career goals of 1. Improving our understanding of the effects of environmental changes on the biogeochemical cycling of SOC in northern soils and 2. Advancing the use of C isotopes and SOC fractionation techniques in biogeochemical investigations. These objectives will be met through concurrent student led projects.