DISSERTATION RESEARCH: Partitioning rhizosphere effects on microbial community structure and carbon cycling across a peatland water table gradient.

泥炭地，如沼泽，是独特的生态系统，只占地球陆地表面的一小部分，但含有大量的碳。泥炭地储存了如此多的碳，因为它们被水饱和，这创造了一个厌氧环境，减缓了复杂有机（含碳）物质的分解。在接下来的100年里，预计干旱频率和严重程度的提高将降低高纬度泥炭地的地下水位高度，导致它们向大气排放更多的碳气体。该项目的目的是确定地下水位降低和相关的植物群落结构变化对北部泥炭地微生物的影响。这些微生物通过分解有机物质来控制碳气体的释放。这项工作将为物理和植物介导的环境变化对微生物群落结构和活动的影响提供新的见解，并将加深对生态系统对气候变化的响应的理解。除了支持研究生的博士论文研究外，该项目还将为波士顿大学的本科生提供学习实验室技术和数据分析方法的机会，领导该项目的研究科学家将开发与泥炭地碳储存相关的教育模块，这些模块将在当地小学和社区节日上展示。微生物（细菌和真菌）类群具有不同的生理和发育历史，这将影响它们对地下水位下降的反应，并有助于生态系统碳和氮循环的变化。随着地下水位下降，维管植物丰度和根系生物量的变化可能通过增加植物对菌根真菌群落的碳分配来进一步影响微生物环境。特别是，本研究旨在确定地下水位降低对微生物群落组成、酶生产和碳矿化的物理效应是否被维管植物丰度的增加和碳分配给菌根真菌群落的增加所放大。该研究将利用正在进行的根际划分实验，跨越缅因州加勒比沼泽的天然地下水位梯度。将比较在根和真菌向内生长的三个根际群落的微生物群落组成，以及安装在地下水位梯度上的隔离核心，以将地下水位物理变化的影响与植物和菌根真菌的生物影响分开。拟议的分析将补充正在进行的微生物功能分析，并确定微生物活动与组成之间的关系，以响应地下水位下降以及存在或不存在植物和菌根输入。

Peatlands, such as bogs, are unique ecosystems that occupy only a small fraction of the Earth's land surface but contain vast quantities of carbon. Peatlands store so much carbon because they are saturated with water, and this creates an anaerobic environment that slows decomposition of complex organic (carbon-containing) substances. Over the next 100 years, heightened drought frequency and severity is projected to reduce water table heights in high latitude peatlands, causing them to emit more carbon gases to the atmosphere. The goal of this project is to identify the effect of water table reduction and associated changes in plant community structure on the microorganisms living in a northern peatland. The release of carbon gasses is controlled by these microorganisms through their decomposition of organic material. The work will provide novel insight into the impact of physical and plant-mediated environmental changes on microbial community structure and activity, and will deepeour understanding of ecosystem responses to climate change. In addition to support the graduate student's doctoral dissertation research, this project will also provide opportunities for Boston University undergraduates to learn laboratory techniques and methods of data analysis, and the research scientists leading this project will develop educational modules related to peatland carbon storage that will be presented at area elementary schools and community festivals.Microbial (bacteria and funga) groups have distinct physiology and developmental histories that will impact their responses to water table decline and contribute to changes in ecosystem carbon and nitrogen cycling. Changes in vascular plant abundance and root biomass associated with water table decline may further impact the microbial environment through increased plant-carbon allocation to mycorrhizal fungal communities. In particular, this research seeks to determine if the physical effect of water table reduction on microbial community composition, enzyme production, and carbon mineralization is amplified by increased vascular plant abundance and carbon allocation to mycorrhizal fungal communities. The research will leverage an ongoing rhizosphere partitioning experiment across a natural water table gradient in Caribou Bog, Maine. Microbial community composition in three rhizosphere communities isolated within root and fungal ingrowth and exclusion cores installed across the water table gradient will be compared to separate the influence ofphysical changes in water table from the biological influence of plants and mycorrhizal fungi. The proposed analyses will complement ongoing microbial functional analyses and identify relationships between microbial activity and composition in response to declines in the water table and in the presence or absence of plant and mycorrrhizal inputs.