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

森林采伐和野火以根本不同的方式扰乱北方森林土壤中的碳循环。在收获过程中，机械扰动将有机层中的有机物物理混合到矿物质土壤中，而有机层在火中的燃烧使有机物发生化学转化，产生灰烬和焦炭，从而增加pH值并释放营养物质。尽管火灾和收获的广泛发生，有几个调查比较火灾和收获对土壤中的碳循环的影响，更少的是，考虑到整个土壤剖面。现有的几项研究结果表明，SOC存储低于30厘米的采伐森林显着增加，在几年后立即干扰和下降。这些碳是以什么形式、以什么速度从地表转移过来的？它是在原地矿化的还是从系统中输出的？在火灾影响的森林，运输的表面有机物似乎是有限的A层，这是survival和典型的薄。为什么？为什么？* 在接下来的五年里，我的研究计划将集中在检查和比较野火和收获的混合木材北方森林中SOC的转化和运输，具体目标是：1。量化所述曲线中SOC的运输速率，2.通过所述轮廓识别SOC稳定化和不稳定化的机制，以及3.评估掩埋和燃烧的SOC存储的生物利用度 * 满足我的计划的短期目标将继续我的职业目标：1。提高我们对环境扰动对陆地系统中SOC地球化学循环的影响的理解; 2）推进C同位素和新的分子技术的使用，结合更经典的地球化学方法（例如物理分馏）。* 直接补充我的省级和国家政府同事正在进行的工作，这项研究将有助于指导围绕气候变化和生物质能的碳和森林管理政策问题。我的研究计划将培养学生在尖端和经典的方法在地球化学和发展技能，问和回答关键问题，在地球化学循环的C。学生、政府科学家和学者之间的互动将提高学生对政策和管理研究的相关性和应用的理解和经验。

Forest harvesting and wildfire disturb the carbon cycle in the soils of the boreal forest in fundamentally different ways. During harvesting mechanical disturbance physically mixes organic matter from the organic layer into the mineral soil while combustion of the organic layer in a fire chemically transforms organic matter and produces ash and char that increases the pH and releases nutrients. Despite the widespread occurrence of fire and harvesting, there are few investigations comparing the effects of fire and harvesting on the carbon cycle in the soil, and fewer still that consider the entire soil profile. Findings from the few available studies indicate that SOC stored below 30 cm in harvested forests increases significantly in the years immediately following disturbance and declines through time. Is this carbon transported from the surface, in what form and at what rate? Is it mineralized in situ or does it get exported from the system? In fire affected forests, transport of surface organic matter appears to be limited to the A horizon, which is surficial and typically thin. Why? ***Over the next five years my research program will focus on examining and comparing the transformation and transport of SOC in wildfire and harvested mixed wood boreal forests with the specific objectives of: 1. quantifying rates of transport of SOC in the profile, 2. identifying mechanisms of SOC stabilization and destabilization through the profile, and 3. assessing the bioavailability of buried and burned SOC stores***Meeting the short term objectives of my program will continue to my career goals of: 1. improving our understanding of the effects of environmental perturbation on the biogeochemical cycling of SOC in terrestrial systems and 2) advancing the use C isotopes and novel molecular techniques, in conjunction with more classical biogeochemical approaches (e.g. physical fractionation). ***Directly complementing work underway by my provincial and national governmental colleagues, this research will assist in guiding carbon and forest management policy issues around climate change and biomass for bioenergy. My research program will train students in cutting edge and classical methods in biogeochemistry and develop skills in asking and answering critical questions in the biogeochemical cycling of C. The interaction between students, government scientists and academics will enhance student understanding of and experience with the relevance and applications of research in policy and management.