The Methane-Oxidizing Bacteria (Methanotrophs)
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...Note: 1—Curry (2007); 2—Liu et al. (2019); 3—Ridgwell et al. (1999); 4—Yu et al. (2017); 5—Aronson et al. (2013); 6—Dijkstra et al. (2012); 7—Dutaur and Verchot (2007); 8—Del Grosso et al. (2000); 9—Weslien et al. (2009); 10—Zhang et al....
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...and landfills (Kirschke et al., 2013). This GHG is mostly consumed in the troposphere through oxidation by hydroxyl (·OH) radicals (90%), whereas only 6% is oxidized by methanotrophs in aerated soils (Kirschke et al., 2013; Le Mer & Roger, 2001). Despite its small proportion, it is a sink that can be directly affected by human interventions through land-use conservation, change or intensification. Soils of forest ecosystems are the most important terrestrial components acting as a sink of atmospheric CH4 (Dutaur & Verchot, 2007). Of the total CH4 consumed in soils at global scale, 60% corresponds to forest ecosystems which uptake 9.16 Tg CH4/year, followed by grasslands with 3.73 Tg CH4/year (Dutaur & Verchot, 2007; Yu, Huang, Zhang, Li, & Sun, 2017). However, declines in soil CH4 uptake has been identified in several forests across the globe, as a consequence of the joint effect of climate change and land-use changes (Han & Zhu, 2020; Ni & Groffman, 2018). Therefore, unravelling the combination of the environmental drivers that determines the CH4 flux in forest soils, both in natural and planted forests, and whether they have a similar behaviour in response to they across biomes, is a crucial step to improve our ability to manage—to some extent—CH4 mitigation and to predict the potential changes of this process under global warming. At soil level, CH4 is produced by methanogenic micro-organism (methanogens) as an end result of the anaerobic digestion of organic matter, but also it is consumed by biological oxidation carried out by methane-oxidizing bacteria (methanotrophs; Le Mer & Roger, 2001). Each of these processes has different environmental requirements, being methanogenesis dominant under anaerobic conditions and methanotrophy active under aerobic conditions (Le Mer & Roger, 2001). Therefore, the net CH4 flux in soils depend on the interplay between aerobic and anaerobic conditions mainly driven by temporal and spatial dynamics of soil water balance (Le Mer & Roger, 2001; Liu, Estiarte, & Peñuelas, 2019; Ni & Groffman, 2018). Furthermore, net negative soil CH4 flux (hereafter soil CH4 uptake) occurs when oxidation process overcomes the methanogenesis (Le Mer & Roger, 2001). Because soil water balance at ecosystem level is controlled by precipitation (water input) and temperature (evaporative output), as well as the vegetation cover, large-scale variations in soil CH4 uptake could be closely linked to climatic variation. However, global scale empirical models considering sole climatic variables have shown to have a limited explicative power (with an explained variance lower than 10%; Dutaur & Verchot, 2007; Liu et al., 2019). In contrast, higher predictive power was reached when soil variables influencing methanotrophy had been added to climatic predictors by Yu et al. (2017). In that study, however, the increase in goodness of fit was achieved by adding complex CH4 flux–soil predictors relationships (i....
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...Note: 1—Curry (2007); 2—Liu et al. (2019); 3—Ridgwell et al. (1999); 4—Yu et al. (2017); 5—Aronson et al. (2013); 6—Dijkstra et al....
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...Note: 1—Curry (2007); 2—Liu et al. (2019); 3—Ridgwell et al. (1999); 4—Yu et al. (2017); 5—Aronson et al. (2013); 6—Dijkstra et al. (2012); 7—Dutaur and Verchot (2007); 8—Del Grosso et al. (2000); 9—Weslien et al. (2009); 10—Zhang et al. (2014); 11—Han and Zhu (2020); 12—Hiltbrunner et al....
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...Note: 1—Curry (2007); 2—Liu et al. (2019); 3—Ridgwell et al. (1999); 4—Yu et al....
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