Physiological and Molecular Diversity of Atmospheric Methane (CH4) Oxidizers in Soil

大气中的甲烷在很大程度上造成了温室效应，由于农业和工业的扩张，甲烷在过去一个世纪里急剧增加。土壤中细菌对甲烷的消耗是大气甲烷浓度的重要调节因子。土壤汇的重要意义在于，它有可能通过对农业、森林砍伐、干旱和土壤变暖等干扰的响应，调解对大气甲烷的长期人为影响。由于土壤每年消耗的大气甲烷量与每年增加的大气甲烷量相当，因此扰动对土壤甲烷汇的累积效应可能对大气中甲烷的积累起重要作用。然而，人们对土壤汇的生物学知之甚少，因为研究人员尚未确定并充分描述实际在原位氧化大气甲烷的土壤细菌。在这个项目中，Steudler博士和他的同事将研究五个温带和针叶林生态系统中大气甲烷氧化剂的生理和分子生态学，在这些生态系统中，干扰对大气甲烷消耗的影响是很有特征的。他们的目标是评估甲烷氧化生物的跨站点多样性在控制土壤甲烷消耗对氮肥、干旱和土壤变暖等干扰的响应中的作用。本研究将提供地理上遥远和生态上不同的森林生态系统中土壤大气甲烷氧化剂微生物多样性的估计，研究这种多样性相对于生物地球化学过程动力学和生态梯度在自然界中的分布情况，并评估这种多样性在控制土壤甲烷消耗对干扰和气候变化的生态系统级响应中的重要性。

Atmospheric methane contributes substantially to the greenhouse effect and has increased dramatically in the past century because of expanding agriculture and industry. Bacterial consumption of methane in soils is an important regulator of atmospheric methane concentration. The significance of the soil sink lies in its potential to mediate long-term, anthropogenic effects on atmospheric methane through its response to disturbances such as agriculture, forest clearcutting, drought, and soil warming. Because the amount of atmospheric methane consumed annually in soils is comparable to the annual increase in atmospheric methane, the cumulative effects of disturbance on the soil methane sink over time could contribute significantly to methane accumulation in the atmosphere. However, the biology of the soil sink is poorly understood because researchers have yet to identify and fully describe the soil bacteria that actually oxidize atmospheric methane in situ. In this project, Dr. Steudler and colleagues will investigate the physiology and molecular ecology of atmospheric methane oxidizers in five temperate and taiga forest ecosystems where disturbance effects on atmospheric methane consumption are well characterized. Their goal is to assess the role of cross-site diversity among the methane oxidizing organisms in controlling the soil methane consumption response to disturbances, including N fertilization, drought and soil warming. This research will provide an estimate of microbial diversity among soil atmospheric methane oxidizers across geographically distant and ecologically distinct forest ecosystems, examine how this diversity is distributed in nature relative to biogeochemical process dynamics and ecological gradients, and assess how important this diversity is in controlling the ecosystem-level response of soil methane consumption to disturbance and climate change.