Soil–methane sink increases with soil age in forefields of Alpine glaciers

摘要: In upland soils aerobic methane-oxidizing bacteria (MOB) catalyze methane (CH4) oxidation, and thus regulate the sole terrestrial sink for atmospheric CH4. While confirmed in mature soils, little is known about this important function young mountainous glacier forefields, which are progressively formed as a result of recession. We assessed four attributes soil CH4 sink, i.e., soil-atmosphere flux (Jatm), oxidation activity (k), MOB abundance variation community composition along 6–120-yr chronosequence two Alpine forefields on siliceous calcareous bedrock. At most sampling locations profiles showed stable uptake CH4, with Jatm range of −0.082 to −2.2 mg CH4 m−2 d−1. Multiple-linear-regression analyses indicated that significantly increased age, whereas k did not. Instead, water content youngest often dry, inactive top layers k < 0.1 h−1, active deeper (0.2 h−1 ≤ k ≤ 11 h−1) more favorable content. With increasing age zone highest gradually moved upwards eventually focused 10–40-cm layer (0.2 h−1 ≤ k ≤ 16 h−1). Copy numbers pmoA genes at both sites, ranging from 2.4 × 103 to 5.5 × 105 copies (g soil w.w.)−1, but also correlated mineral nitrogen Terminal restriction-fragment-length-polymorphism cluster differences apparently related bedrock type rather than age. Yet, regardless type, established within few years development, values comparable decades. Thus, have potential consume substantial amounts should be incorporated into future estimates global uptake.