Collaborative Research: Understanding biophysical drivers of the CH4 source sink transition in Northern Forests

合作研究：了解北部森林 CH4 源汇转变的生物物理驱动因素

• 批准号: 2208658
• 负责人: Shawn Fraver
• 金额: $ 23.97万
• 依托单位: University of Maine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-11-01 至 2025-10-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2208658&HistoricalAwards=false
• 关键词: Collaborative; Research; Understanding; biophysical; drivers

Methane is second only to carbon dioxide in its contribution to human-induced climate change due to its global warming potential, which is 34 times greater than that of CO2. Microorganisms in wet landscapes tend to release methane, whereas those in dry ones tend to take up the gas from Earth's atmosphere. Researchers at the Howland Research Forest in Maine have been measuring methane fluctuations across this sub-boreal forest since 2012. Their studies have found that the forest usually serves as a methane "sink" due to microbial consumption, although occasionally, under extremely wet conditions, the reverse can be true. This research site provides an ideal opportunity to study the conditions under which a forest would switch from a net sink to become a source of atmospheric methane. Under future climate change scenarios, the region is expected to become warmer and wetter, conditions that may induce a shift from methane sink to source, with the potential to have an impact on atmospheric methane concentrations at regional to global scale. This project will examine how forest soil microbial communities will change in response to climate warming, to identify the conditions that may lead forests to switch from being a methane sink to more of a source. The project will also support the cross-disciplinary training of graduate and undergraduate students and postdoctoral research scholars, including those from underrepresented groups in science. A series of public talks will be convened, and short videos and StoryMaps focused on science outreach will be paired with “scientist in the classroom” visits to local high schools. The project will host an open house for students and the public at the Howland Research Forest to learn about this important research. This study aims to identify - through the integration of field observations, laboratory analyses, and modeling - the conditions and mechanisms driving methane sink vs source activity in forests, using the Howland Research Forest in Maine as a case study. The project's novel approach focuses on three key areas to improve understanding of methane in such habitats: 1) identify the roles and response of soil microbial communities, specifically, methanogens and methanotrophs (and their functional guilds), in driving methane flux across environmental gradients; 2) understand and quantify how wet vs dry landscape microsites, and belowground vs. aboveground components within a forest contribute to seasonal and annual methane fluxes; and 3) integrate knowledge gained from field and laboratory analyses to inform and improve ecosystem process models. A suite of in-situ and lab-based experimental measures of methane production and oxidation, stable isotopes, and profiles of microbial community composition and function will be used to understand the mechanisms, processes, and feedbacks driving methane sink/source activity from site to landscape levels. At the site level, multi-scale observations of soil and aboveground methane fluxes, microbial traits, and associated in-situ environmental conditions will be obtained. To further understand and quantify methane response, in-situ and laboratory manipulation experiments to identify the role of functional guild activity, under changing environmental conditions, in regulating methane production/oxidation and ultimately net methane flux to and from the atmosphere will be employed. Finally, these data, integrated with project data-enhanced Microbial Model for Methane Dynamics-Dual Arrhenius Michaels Menten (M3D-DAMM) and Community Land Model-Microbe (CLM-Microbe) process models, will allow researchers to identify seasonal and annual methane sink/source activity at the landscape level within Howland Forest from the present to 2100. The research will include training at the undergraduate, graduate and postdoctoral levels, as well as a variety of outreach activities to engage high school students and the public.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

由于其全球变暖潜力，甲烷对二氧化碳的贡献仅次于二氧化碳，这是其全球变暖潜力，其比CO2大34倍。潮湿景观中的微生物倾向于释放甲烷，而干燥的甲烷却倾向于从地球大气中占用气体。自2012年以来，缅因州霍兰德研究森林的研究人员一直在测量这一亚谷林的甲烷波动。他们的研究发现，由于微生物的消耗，该森林通常是甲烷“下沉”，尽管偶尔在极度潮湿的条件下，相反的情况可能是正确的。该研究地点提供了研究森林将从净水槽切换为大气甲烷的条件的理想机会。在未来的气候变化方案下，该地区有望变得更加温暖和湿润，可能导致从甲烷下水道转向来源的条件，并有可能影响区域与全球尺度的大气甲烷浓度产生影响。该项目将研究森林土壤微生物群落如何随着气候变暖的响应而变化，以确定可能导致森林从成为甲烷下水道转变为更多来源的条件。该项目还将支持研究生和本科生以及博士后研究学者的跨学科培训，包括科学领域代表性不足的群体。将召集一系列公开演讲，以科学外展的重点进行简短的视频和故事图，将与“在课堂上的科学家”访问当地高中的访问。该项目将在霍兰德研究森林（Howland Research Forest）的学生和公众举办开放日，以了解这项重要的研究。这项研究旨在通过缅因州的霍兰德研究森林作为案例研究来确定 - 通过整合现场观测，实验室分析和建模 - 驱动甲烷水槽与森林中的源活动的条件和机制。该项目的新方法集中在三个关键领域，以提高这种栖息地中对甲烷的理解：1）确定土壤微生物群落的作用和反应，特别是甲烷植物和甲烷营养（及其功能性行会），在跨环境梯度驱动甲烷通量方面； 2）了解和量化湿地与干景观微地板的湿与森林中的地下成分以及地下成分有助于季节性和每年的甲烷通量； 3）从现场和实验室分析中获得的综合知识，以告知和改善生态系统过程模型。一套基于原位和实验室的甲烷产生和氧化，稳定的同位素以及微生物群落组成和功能的概要的套件将用于了解驱动甲烷水槽/源源活动从现场到景观水平的机制，过程和反馈。在现场水平上，将获得对土壤和地上甲烷通量，微生物性状以及相关的原位环境条件的多尺度观察。为了进一步理解和量化甲烷反应，在不断变化的环境条件下，在确定甲基烷生产/氧化和最终从大气中确定甲基甲烷通量和最终从大气中确定净甲烷通量来确定功能性公会活性的作用。最后，这些数据与项目数据增强的微生物模型集成了甲烷动力学双重二线Arrhenius Michaels Menten（M3D-DAMM）（M3D-DAMM）和社区土地模型 - 菌（CLM-MICROBE）过程模型，将使研究人员能够识别季节性和每年的甲烷水槽/源水源活动，包括层次的研究，包括研究层的层次训练。作为与高中生和公众吸引的各种外展活动。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和更广泛的影响评估标准来评估，被认为是珍贵的支持。