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.
