Methane uptake by grassland soils: Biogeochemistry, microbial ecology and integrative modeling

甲烷是一种强大的温室气体，但对其过去和未来在大气中的浓度的控制仍然非常不确定。 一组特定的土壤细菌（甲烷营养菌）消耗甲烷是全球甲烷预算的关键部分，温带草原贡献了重要部分。 尽管目前的大气甲烷消耗模型将这种消耗视为常数，但有明确的证据表明，其消耗率随气候变化而变化，这表明未来的气候变化可能会改变其规模。 这项工作的总体目标是提高对甲烷吸收的理解，以便更好地预测其对气候变化的反应。 实现这一总体目标的努力分为3个目标。 首先，研究人员将从覆盖北美大平原草原气候多样性的研究地点收集甲烷吸收及其控制的实地数据。 其次，研究人员将通过对这些地点土壤的实验室分析来量化对甲烷吸收的控制。 甲烷吸收的大部分气候敏感性取决于甲烷氧化菌对土壤温度和湿度变化的反应方式，并且有证据表明这种环境敏感性因甲烷氧化菌物种而异。 因此，这第二个目标需要测量甲烷氧化菌的环境敏感性如何在存在不同甲烷氧化菌物种的研究地点之间变化。 最后，研究人员将统计评估他们的现场和实验室的研究结果，并使用它们来开发一种新型的甲烷吸收预测模型，其中包括甲烷氧化菌物种差异的重要性。这项研究将解决一个基本问题，即细菌多样性在影响生态系统工作方式中的重要性。 人们普遍认识到，例如，仙人掌、松树和草对干旱胁迫的反应不同，但对不同细菌物种对环境变化的反应知之甚少。 因此，尽管许多研究已经证明土壤细菌物种因地而异，但仍然很难预测这些多样性的变化如何影响生态系统的功能。 该项目还将通过培训和雇用博士后学生、一名研究生和10多名本科生，为劳动力发展做出贡献。 这项研究不仅将吸引本科院校（奥古斯塔纳学院，SD）和R-1研究型大学（科罗拉多州，内布拉斯加大学）的学生，但将加强这些机构的教师之间的网络，并将包括从CSU普韦布洛招聘西班牙裔美国本科生参加夏季研究活动。

Methane is a powerful greenhouse gas, but controls on its past and future concentration in the atmosphere remain highly uncertain. The consumption of methane by a specific group of soil bacteria (methanotrophs) is a key part of the global methane budget, with temperate grasslands contributing an important fraction. Although current models for atmospheric methane treat this consumption as constant, there is clear evidence that its rate varies with climate, suggesting that future climate change may alter its magnitude. The overall goal of this work is to improve understanding of methane uptake so that its response to climate change can be better predicted. Efforts to achieve this overall goal are broken down into 3 objectives. First, the investigators will collect field data on methane uptake and its controls from study sites that cover the climatic diversity of the North American Great Plains grasslands. Second, the investigators will quantify the controls on methane uptake with laboratory assays on soils from these sites. Much of the climate sensitivity of methane uptake hinges on the way that the methanotrophic bacteria respond to variation in soil temperature and moisture, and there is evidence that this environmental sensitivity differs from one methanotroph species to another. Thus, this second objective requires measuring how the environmental sensitivity of methanotrophs varies among study sites where different methanotroph species are present. Finally, the investigators will statistically evaluate their field and laboratory findings and use them to develop a new type of predictive model for methane uptake that incorporates the importance of methanotroph species differences.This study will address a fundamental question about the importance of bacterial diversity in affecting the way that ecosystems work. It is well recognized that, for example, cactus, pine trees and grasses respond differently to drought stress, but the responses of different bacterial species to environmental change are poorly understood. Thus, even though a number of studies have now documented that soil bacterial species vary from place to place, it remains difficult to predict how these changes in diversity affect the way that ecosystems function. This project also will contribute to workforce development by training and employing post-doctoral students, a graduate student and more than 10 undergraduate students. The research will not only engage students from undergraduate institutions (Augustana College, SD) and R-1 research universities (Colorado State, University of Nebraska), but will enhance networking between faculty at these institutions, and will include recruitment of Hispanic-American undergraduate students from CSU-Pueblo to participate in summer research activities.