The tiny majority: how microbes mediate ecosystem functioning under anthropogenic stressors in boreal environments

生态系统对气候变化的反馈和集约化土地利用管理是未来全球气候系统命运的一些最大的不确定性来源。土壤和水生沉积物中的微生物群落是这些反馈的主要参与者，负责有机物的处理和温室气体的释放。虽然环境微生物学领域似乎一直处于令人兴奋的技术动态状态，但环境微生物学与生态系统生态学之间仍然存在根本性的脱节。这在很大程度上是因为环境微生物学方法的弱点，这些弱点源于目标的小尺寸和高数量的性质。在过去的几十年里，基于单基因的群落指纹识别方法和环境基因组学教会了我们很多东西，但它们也强调了环境中绝大多数微生物和许多种类的微生物基因是“已知-未知”的。将微生物群落及其活动的原位研究与靶向富集和分离方法相结合的研究项目为理解微生物群落如何动态塑造我们的环境提供了重要的希望。在这个框架内，这项拟议工作的目标分为4个学生主导的项目主题：在全球独特的气候变化模拟实验中，微生物对北方沼泽泥炭地变暖和二氧化碳浓度增加的反馈(1)，对安大略省远北地区世界第二大泥炭地复群的永久冻土融化的反馈(2)；为了提高生物能源原料生产而加强北方森林采伐的微生物多样性和生态系统功能的潜在损失(3)，以及变化的陆生植物群落和凋落物输入如何影响北方湖泊沿岸沉积物中的碳和温室气体产生(4)。这项跨学科研究将解决生物圈对全球气候和土地利用变化的反馈等紧迫问题，并将为新兴的国家和国际碳经济时代的资源管理提供科学指导。同时，它将努力丰富和分离相关的未知微生物，并描述其代谢，生理学和遗传学的基本特征，以帮助消除环境微生物学认识论中的长期限制。

Ecosystem feedbacks to climate change and intensive land use management represent some of the biggest sources of uncertainty in the fate of the future global climate system. Consortia of microorganisms in soils and aquatic sediments are primary players in these feedbacks, responsible for the processing of organic matter and the release of greenhouse gasses. Although the field of environmental microbiology is in a seemingly constant state of exciting technological dynamism, there is still a fundamental disconnect between environmental microbiology and ecosystem ecology. This is in large part because of weaknesses in methods in environmental microbiology that stem from the nature of the small size and high numbers of the targets. Single gene based community fingerprinting methods and environmental genomics have taught us a lot in the past decades, but they also have highlighted that the vast majority of microbes and many classes of microbial genes in the environment are “known-unknowns”. A research program that combines in situ studies of microbial communities and their activities together with targeted-enrichment and isolation approaches offers important promise for progress in understanding how microbial communities dynamically shape our environment. Within this framework, the goals of this proposed work are grouped in to 4 student-led project themes: microbial feedbacks to warming and increased carbon dioxide concentrations across boreal fen peatlands in a globally unique climate change simulation experiment (1), feedbacks to permafrost melt in the 2nd largest peatland complex in the world in the Far North of Ontario (2); the potential loss of microbial diversity and ecosystem functioning under intensified boreal forest harvests for enhanced bioenergy feedstock production (3), and how changing terrestrial plant communities and litter inputs influence carbon and greenhouse gas production in littoral sediments of boreal lakes (4). This transdisciplinary research will address pressing issues in biosphere feedbacks to global climate and land use change, and it will provide scientific guidance for resource management in the era of burgeoning national and international carbon economies. Simultaneously it will strive to enrich for and isolate relevant, unknown microorganisms and characterize fundamentals of their metabolism, physiology, and genetics to help chip away at longstanding constraints in the epistemology of environmental microbiology.