Soil methane oxidation and land-use change - from process to mitigation

Global atmospheric methane (CH4) concentrations are now approaching 1800 ppbv as a result of the growing imbalance between the net CH4 emissions from natural and anthropogenic sources of this potent greenhouse gas, and its consumption by physical and biological processes. The main focus of this review is on how land-use change and soil management can be used to correct this imbalance. Currently, the main terrestrial source for CH4 is from natural wetlands and irrigated rice cultivation; although improvements in water management during rice production have resulted in major reductions of CH4 emissions from this source. Afforestation and reforestation can also enhance soil CH4 oxidation by influencing the composition and activity of the soil methanotroph (aerobic proteobacteria) community. The effects of these and other land-use changes on soil CH4 oxidation are not generally well understood, but are known to influence this process through their effects on a range of soil properties such as soil moisture, nitrogen status, and pH that also affects methanotroph community structure and function. Recent advances in molecular techniques have confirmed the central role of methanotroph communities in regulating soil CH4 consumption by revealing how they respond to land-use change. Community-level molecular analyses of methanotroph populations under different conditions now provide new insights into the distinct traits of the different subgroups and their ecology. These advances in understanding the abiotic and biological processes regulating soil CH4 oxidation now offers the possibility of being able to predict which land-use and management practices, especially for afforestation and reforestation, will achieve high soil CH4 oxidation rates They also improve the prospects for integrated assessment of the atmospheric impacts on the global greenhouse gas budget from net soil emissions of CH4, N2O, and CO2 with land use and management change. (C) 2014 Elsevier Ltd. All rights reserved.