Collaborative Research: Long-term carbon storage shifts in high-latitude peatlands with paleoclimate change: Linking peatland modeling with paleoecology and paleohydrology

这是对阿拉斯加北极泥炭地档案中古气候与长期碳积累之间关系的迭代数据模型研究。该假说认为，气候通过与生产和分解过程相关的温度和湿度变化来控制泥炭地的碳储量。利用从晚冰川期到全新世的两个北极地区的现有泥炭地岩心，提供了多种气候情景来研究碳封存。例如，该小组假设温暖、干燥的间隔会导致泥炭地碳储量下降，而凉爽、潮湿的气候会导致碳封存增加。利用新的工具，包括化合物特异性同位素和生物标志物分析，以及现有的传统古气候代用物，如花粉、大型化石和苔藓植物，研究人员将产生详细的气候和水文重建，并进行高分辨率的AMS-14C测年。C和体积密度测量将提供从冰川晚期到现在的碳积累速率，并使研究小组能够使用新开发的机械泥炭地积累模型来测试他们的碳封存-气候假设。由于高纬度温暖地区以及北极和亚北极泥炭地为气候系统提供了正碳反馈和负碳反馈，因此在我们对量级和时空尺度的理解中加入古视角是很重要的。本研究将结合高纬度泥炭地在最后一次冰期-间冰期循环中古生态/古气候变化的详细分析（通过苔藓植物、化合物特异性同位素分析、花粉和宏观化石分析）与不同环境（即潮湿与干燥的muskegs）中碳固存的定量分析。这些古泥炭地历史将提供长期的碳封存记录，可用于与来自相同沉积物的古气候重建、冰芯、海洋记录和湖泊地层学的比较。全新世泥炭地模式将利用这些独立的古气候数据，在几十年到几千年的时间尺度上模拟北方泥炭地的碳水耦合动态。然后，可以将模型模拟的碳积累记录与泥炭地历史进行比较，并根据植物组成、生产力和分解来评估差异。这种迭代模型数据研究将提供长期的经验信息，以评估水文循环在未来湿地碳循环中的作用，以及过去气候和植被在数千年碳封存中的重要性。新取样的选定地点包括阿拉斯加的泥炭地。在图里克湖的北坡，有一个广泛的生态数据库，以及西部梅萨遗址的北极山麓。AMS 14C年龄，以及Pb-210和Cs-137，将与C和体积密度结合使用，以确定每个站点的碳积累。苔藓植物和同位素/生物标记物的分析将提供确定的湿度制度以及由于火山灰沉积在这些地点可能发生的水化学变化。特别感兴趣的是气候间隔，如Bolling-Allerod/新仙女木期、全新世早期、前北方纪和8200年事件、全新世中期、新冰川期、小冰河期和过去50年。本项目将涉及至少4篇本科论文和1篇博士后论文。PI在指导本科生和指导研究生实地和实验室项目方面有着良好的记录，她的许多前顾问在同行评议的期刊上发表了他们的研究成果。学生将有机会展示地方、州和国家层面的成果。该组织将继续其在科学项目方面的长期领导地位，在NASA/GISS为少数民族和哥伦比亚大学举办的暑期项目中培训高中生和教师。该校地球与环境科学系的研究生和本科生，以及当地博物馆和公共项目的外联。他们打算在拉蒙特·多尔蒂地球观测站（访问北极/亚北极夏季教师）项目中聘请一名K-12教师参与他们的实地和实验室研究，以产生深远的影响。此外，他们的分析可以用于哥伦比亚大学PI教授的湿地和气候变化，陆地古气候课程，以及植物生态学和古生态学研讨会，以及UNH PI教授的课程（生物地球化学和环境建模）。这项工作的结果和结论将对北极气候政策、生态系统管理和教育产生影响。

This is an iterative data-model investigation of the relationship between paleoclimate and long-term carbon accumulation from Alaskan arctic peatland archives. The hypothesis is that climate controls carbon storage in peatlands through shifts in temperature and moisture related processes of production and decomposition. Use of an existing set of peatland cores from two arctic regions from the late-glacial to the Holocene offers a variety of climate scenarios to examine carbon sequestration. For example, the group hypothesizes that warm, dry intervals result in peatland carbon storage decline, while cool, wet climates result in increased carbon sequestration. Using new tools, including compound-specific isotope and biomarker analysis, and existing traditional paleoclimate proxies such as pollen, macrofossils, and bryophytes, the researchers will produce detailed climate and hydrological reconstructions, and high resolution AMS-14C dating, C and bulk density measurements will provide carbon accumulation rates from the late-glacial to the present and enable the team to test their carbon sequestration-climate hypotheses using a newly-developed mechanistic peatland accumulation model. As high latitudes warm and arctic and subarctic peatlands provide positive and negative carbon feedbacks to the climate system, it is important to add the paleo-perspective to our understanding of magnitude and temporal and spatial scales. This research will couple detailed analysis of changes in paleoecology/paleoclimate (through bryophyte, compound-specific isotope analysis, pollen, and macrofossil analysis) in high latitude peatlands over the last glacial-interglacial cycle with quantification of carbon sequestration in different environments (i.e., wet vs. drier muskegs). These paleo-peatland histories will provide long-term carbon sequestration records, which can be used for comparisons with paleoclimate reconstructions from the same sediments, as well as ice cores, marine records, and lake stratigraphy. The independent paleoclimate data will be utilized by the new Holocene Peatland Model to simulate coupled carbon and water dynamics of northern peatlands at an annual time step over time scales of decades to millennia. The model-simulated carbon accumulation record can be then compared with the peatland histories, and differences evaluated in terms of plant composition, productivity, and decomposition. This iterative model-data research will provide long-term empirical information necessary to evaluate the role of the hydrological cycle in future wetland carbon cycling, and the past importance of climate and vegetation in sequestering carbon over millennia.The selected sites for new sampling include peatlands of Alaska?s North Slope at Toolik Lake where an extensive ecological database exists as well as the arctic foothills of the western Mesa site. AMS 14C ages, as well as Pb-210 and Cs-137, will be used in conjunction with C and bulk density to determine carbon accumulation for each site. Analysis of bryophyte and isotopes/biomarkers will provide defined moisture regimes as well as possible water chemistry changes due to volcanic ash deposition in these sites. Of particular interest are climatic intervals such as the Bolling-Allerod/Younger Dryas, the early Holocene, the Preboreal and 8200-yr events, mid-Holocene, the Neoglacial, Little Ice Age, and the last 50 years. This project will involve at least 4 undergraduate theses and one postdoc. The PI has a well-documented record of mentoring undergraduates and advising graduate students in field and lab-based programs, with many of her former advisees publishing their results in peer-reviewed journals. Students will have an opportunity to present results at the local, state, and national levels. The group will continue its long leadership in science programs training high school students and teachers at NASA/GISS summer program for minorities and Columbia University?s Department of Earth and Environmental Science graduate and undergraduate students, as well as local outreach to museums and public programs. They intend to engage a K-12 teacher in their field and lab research in the Lamont Doherty Earth Observatory VAST (Visiting Arctic/subarctic Summer Teacher) program for far-ranging impact. Additionally, their analyses can be utilized for the Columbia University courses the PI teaches on Wetlands and Climate Change, Terrestrial Paleoclimate, as well as seminars in Plant Ecology and Paleoecology, and in courses the UNH PI teaches (Biogeochemistry and Environmental Modeling). The results and conclusions of this work will have implications for arctic climate policy, ecosystem management, and education.