Collaborative Research (ETBC): Climate Warming and Northern Peatland Decomposition, Accumulation and Carbon Sequestration Examined Through Molecular and Paleohydrological Analysis

北部泥炭地（北纬50°以上）的广泛存在是亚北极系统的一个独特而重要的特征，具有全球影响。北部泥炭地大气碳净固存（274-489 Pg C）在全新世全球碳循环中发挥了重要作用，并将继续成为人类世碳循环的重要因素。更清楚地了解气候如何影响泥炭的积累和分解速率，以及最终的净碳固存，对于预测当前和未来的变暖将如何影响北部泥炭地和全球碳循环至关重要。我们提出了一种新的方法，以获得气候变暖对泥炭分解率和净积累率的作用的机制理解，这些泥炭是在以前的国家科学基金会支持的项目中从西西伯利亚低地（俄罗斯）和詹姆斯湾低地（加拿大）收集的核心网络中收集的，在一个单独的国家科学基金会支持的项目中。泥炭积累和碳固存的净速率将根据放射性碳定年的岩心计算。以地下水位深度变化为代表的水文变化，将利用变形虫分析直接计算出核心样地的水文变化。泥炭样品的详细化学特征将用于开发泥炭分解的分子指标。然后将应用这些分子指标和成岩模型来量化泥炭分解的速率和程度，以及生产和分解在确定碳固存速率方面的相对重要性。仪器气候数据和已发表的古气候研究将用于研究气候、水文、分解和积累之间的联系以及控制泥炭产生和分解之间平衡的机制。鉴于目前和预计下个世纪亚北极的变暖，建议的研究将集中在全新世热极大期（~8,000-4,000 Cal yr BP）、中世纪暖期（~1,100 - 700 Cal yr BP）和现代变暖的比较影响上。气候变暖对亚北极系统的水文、生物群和生物地球化学循环产生了不成比例的巨大影响。在全新世期间，北部泥炭地一直是土壤和大气碳循环的主要参与者，这项研究将为气候如何影响这些过程提供更清晰的画面。将开发新的方法和潜在的变革概念，以定量了解控制北部泥炭地碳固存和释放的机制。该研究将提供一个数据库，其中包括来自西伯利亚和加拿大中部约40个核心地点和约100个地表地点的关于过去和现在泥炭地生物地球化学条件的2万多次详细分析。本项目将为Benner？他在南加州大学的实验室和麦克唐纳？他在加州大学洛杉矶分校的实验室里说。他们将在科学会议上展示他们的数据，并准备在同行评议的期刊上发表文章。Benner和MacDonald教授的本科和研究生课程涵盖了全球碳循环和气候变化的各个方面，从这个项目中收集的数据将作为这些课程的具体例子。这种将活跃的研究项目中的信息带入课堂的方法已被证明对提高学生的科学意识和兴趣非常有效。本项目将招收一名本科生(Benner？作为南加州大学麦哲伦学者项目的一部分，为本科生提供研究经验。研究结果将公布在研究网站上，数据将提供给适当的国家和国际数据库，以供广泛使用。

The widespread occurrence of northern peatlands (above 50°N) is a distinctive and important attribute of the subarctic system that has global ramifications. The net sequestration of atmospheric carbon in northern peatlands (274-489 Pg C) has played a significant role in the global carbon cycle during the Holocene and will continue to be an important factor in the carbon cycle of the Anthropocene. A clearer understanding of how climate affects peat accumulation and decomposition rates, and ultimately net carbon sequestration, is critical for predicting how current and future warming will impact northern peatlands and the global carbon cycle. We propose a novel approach to gain a mechanistic understanding of the role of climate warming on rates of peat decomposition and net accumulation in a network of cores collected from the West Siberian Lowland (Russia), under a previous NSF-supported project, and the James Bay Lowland (Canada), under a separate NSF-supported project. Net rates of peat accumulation and carbon sequestration will be calculated from radiocarbon-dated cores. Hydrological changes, represented by changes in water table depth, will be directly calculated for the core sites using testate amoebae analysis. Detailed chemical characterizations of peat samples will be used to develop molecular indicators of peat decomposition. These molecular indicators and diagenesis models will then be applied to quantify rates and extent of peat decomposition and the relative importance of production and decomposition in determining carbon sequestration rates. Instrumental climate data and published paleoclimate research will be used to examine linkages among climate, hydrology, decomposition and accumulation and the mechanisms controlling the balance between peat production and decomposition. In view of current and anticipated warming of the subarctic over the next century, the proposed studies will focus on the Holocene Thermal Maximum (~8,000-4,000 Cal yr BP), the Medieval Warm Period (~1,100 to 700 Cal yr BP) and the comparative impacts of Modern Warming. Climate warming is having a disproportionately large affect on the hydrology, biota and biogeochemical cycles of the subarctic system. Northern peatlands have been major players in soil and atmospheric carbon cycling during the Holocene, and this study will provide a clearer picture of how climate shapes these processes. Novel approaches and potentially transformative concepts will be developed to provide a quantitative understanding of the mechanisms controlling carbon sequestration and release in northern peatlands. The research will provide a data base of over 20,000 detailed assays on past and present peatland biogeochemical conditions from ~40 core sites and ~100 surface sites in Siberia and central Canada. This project will provide training, experience and support for a postdoctoral associate in Benner?s laboratory at USC and a graduate student in MacDonald?s laboratory at UCLA. They will present their data at scientific meetings and prepare articles for publication in peer-reviewed journals. Benner and MacDonald teach undergraduate and graduate classes that cover various aspects of the global carbon cycle and climate change, and data collected from this project will be used as specific examples in these classes. This approach of bringing information from active research programs into the classroom has proven to be very effective for increasing student awareness and interest in science. An undergraduate student will be recruited to participate in this project (Benner?s laboratory) as part of the Magellan Scholars program at USC to provide research experiences for undergraduates. Results will be posted on research websites and data contributed to appropriate national and international data bases for widespread use.