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Wetland soils span a wide range of pH values, from bogs and pocosins with pH values of ~4 or less to riparian floodplains and other wetlands where the pH can exceed 7.5 (e.g., Jacob et al., 2013; Richardson, 2003). We focus here on low pH wetlands since that is where pH has the largest inhibitory effect on carbon mineralization. Rates of CH₄ production and emission are low in acidic wetlands and increase when pH is experimentally increased (Dunfield et al., 1993; Ye et al., 2012). The suppression of CH₄ emissions by low pH occurs through direct inhibitory effects on the hydrogenotrophic and acetoclastic methanogenic pathways as well as interference with the fermentative processes that generate the substrates used by methanogens (Ye et al., 2012). Atmospheric acid deposition also depresses CH₄ emission rates, although this effect is mediated by the competitive suppression of methanogenesis by NO₃^– and/or SO₄^2– rather than a direct pH effect (Gauci et al., 2004; Watson & Nedwell, 1998). Rates of soil carbon mineralization to CO₂ are also limited by low pH due to the inhibitory effects of pH on fermentation (Ye et al., 2012), the suppression of phenol oxidase activity (Williams et al., 2000; Xiang et al., 2013), a microbial community characterized by slow‐growing bacteria (Hartman et al., 2008), and/or the encapsulation of reactive organic matter by humic acids (see Physical protection in Section 3.3.2). Experimental increases of soil pH in the lab often lead to higher rates of CO₂ production (e.g., Ye et al., 2012) although a multi‐year field experiment found a decrease in soil CO₂ production rates in response to increased pH, perhaps because the native microbial community was well adapted to the original low pH environment (Keller et al., 2005).