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

北部泥炭地(50°N以上)的广泛出现是具有全球影响的亚北极系统的一个独特而重要的属性。北部泥炭地(274-489pgC)大气碳的净固存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中的一个重要因素。更清楚地了解气候如何影响泥炭积累和分解速率，最终影响净碳封存，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来从机制上理解气候变暖对泥炭分解和净积累速率的影响，该网络是在之前NSF支持的项目下从西西伯利亚低地(俄罗斯)和詹姆斯湾低地(加拿大)收集的，在NSF支持的单独项目下收集的。泥炭堆积和碳固存的净速率将从放射性碳测年岩心计算出来。以地下水位深度变化为代表的水文变化将使用变形虫分析直接计算核心地点的水文变化。泥炭样品的详细化学特征将用于开发泥炭分解的分子指示剂。这些分子指示剂和成岩作用模型将被用于量化泥炭分解的速度和程度，以及在确定碳固存速率时生产和分解的相对重要性。工具性气候数据和已发表的古气候研究将被用来研究气候、水文、分解和积累之间的联系，以及控制泥炭生产和分解之间平衡的机制。鉴于当前和预计下个世纪亚北极地区将变暖，拟议的研究将集中在全新世最高温度(~8000-4000Cal yr BP)、中世纪暖期(~1100至700 Cal yr BP)以及现代变暖的比较影响上。气候变暖正在对亚北极系统的水文、生物群和生物地球化学循环产生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塑造这些过程提供更清晰的图景。将开发新的方法和潜在的变革性概念，以提供对北部泥炭地碳固定和释放的控制机制的定量了解。这项研究将提供西伯利亚和加拿大中部约40个核心地点和约100个表层地点过去和现在泥炭地生物地球化学条件的20,000多个详细分析的数据库。该项目将为南加州大学本纳？S实验室的博士后助理和加州大学洛杉矶分校麦克唐纳？S实验室的研究生提供培训、经验和支持。他们将在科学会议上展示他们的数据，并准备发表在同行评议期刊上的文章。本纳和麦克唐纳教授本科生和研究生课程，涵盖全球碳循环和气候变化的各个方面，从这个项目收集的数据将作为这些课程的具体例子。这种从积极的研究项目中将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。作为南加州大学麦哲伦学者计划的一部分，将招募一名本科生参与这个项目(本纳？S实验室)，为本科生提供研究经验。结果将在研究网站上公布，数据将提供给适当的国家和国际数据库，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.