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: 2208659
• 负责人: Debjani Sihi
• 金额: $ 32.92万
• 依托单位: Emory University
• 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=2208659&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.

甲烷对人类引起的气候变化的影响仅次于二氧化碳，因为其全球变暖潜力是二氧化碳的 34 倍。潮湿环境中的微生物倾向于释放甲烷，而干燥环境中的微生物则倾向于从地球大气中吸收气体。 自 2012 年以来，缅因州豪兰研究森林的研究人员一直在测量这片亚寒带森林的甲烷波动。他们的研究发现，由于微生物的消耗，森林通常充当甲烷“汇”，尽管偶尔在极端潮湿的条件下，情况也可能相反。 该研究地点提供了一个理想的机会来研究森林从净汇转变为大气甲烷来源的条件。在未来的气候变化情景下，预计该地区将变得更加温暖和湿润，这种情况可能会导致甲烷从汇向源头的转变，并有可能对区域到全球范围内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因气候变暖而发生变化，以确定可能导致森林从甲烷汇转变为甲烷源的条件。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，包括来自科学领域代表性不足群体的学者。将召开一系列公开讲座，重点关注科学推广的短视频和故事地图将与对当地高中的“课堂上的科学家”访问相结合。该项目将在豪兰研究森林为学生和公众举办开放日，以了解这项重要的研究。本研究旨在通过结合实地观察、实验室分析和建模，以缅因州豪兰研究森林为案例研究，确定驱动森林中甲烷汇与源活动的条件和机制。该项目的新方法侧重于三个关键领域，以提高对此类栖息地中甲烷的了解：1）确定土壤微生物群落，特别是产甲烷菌和甲烷氧化菌（及其功能群）在驱动甲烷通量跨越环境梯度方面的作用和反应； 2) 了解并量化森林内湿与干景观微场地以及地下与地上部分对季节性和年度甲烷通量的影响； 3）整合从现场和实验室分析中获得的知识，以告知和改进生态系统过程模型。一套关于甲烷产生和氧化、稳定同位素以及微生物群落组成和功能概况的原位和基于实验室的实验测量将用于了解驱动甲烷汇/源活动从场地到景观水平的机制、过程和反馈。在现场层面，将获得土壤和地上甲烷通量、微生物特征以及相关现场环境条件的多尺度观测。为了进一步了解和量化甲烷响应，将采用原位和实验室操纵实验来确定功能行会活动在不断变化的环境条件下在调节甲烷产生/氧化以及最终进出大气的净甲烷通量中的作用。最后，这些数据与项目数据增强型甲烷动力学微生物模型 - 双阿伦尼乌斯迈克尔门滕 (M3D-DAMM) 和社区土地模型 - 微生物 (CLM-微生物) 过程模型相结合，将使研究人员能够识别从现在到 2100 年豪兰森林内景观水平的季节性和年度甲烷汇/源活动。该研究将包括本科生、研究生和博士后级别的培训，例如 该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。