Potential soil methane oxidation in naturally regenerated oak-dominated temperate deciduous forest stands responds to soil water status regardless of their age—an intact core incubation study
2022
Bras, Nicolas | Plain, Caroline | Epron, Daniel
KEY MESSAGE: Potential CH₄ oxidation in the top soil layer increased with decreasing soil water content in spring but was inhibited during severe summer drought in naturally-regenerated oak-dominated temperate deciduous forest stands regardless of their age. No direct effect of mineral nitrogen on soil CH₄ oxidation was found. Soil CH₄ oxidation in temperate forests could be reduced by extreme climatic events. CONTEXT: The oxidation of atmospheric methane (CH₄) by methanotrophic bacteria in forest soils is an important but overlooked ecosystem service. AIM: Our objective was to determine which factors drive variations in soil CH₄ oxidation in oak-dominated temperate deciduous forest stands of different ages. METHODS: Soil samples were collected in 16 stands aged 20 to 143 years in periods of high and low soil water content (SWC). The potential rate of soil CH₄ oxidation was measured by incubating the first five centimetres of intact soil cores at 20 °C. RESULTS: SWC was the main driver accounting for variations in CH₄ oxidation. In spring, a two-fold reduction in SWC greatly increased CH₄ oxidation. But when the soil was dry in late summer, a further reduction in SWC led to a decrease in CH₄ oxidation in the top soil layer. No direct effect of mineral nitrogen on soil CH₄ oxidation was found. CONCLUSIONS: With regard to soil CH₄ oxidation, naturally regenerated forest stands contribute equally to climate change mitigation regardless of their age. Considering future climate scenarios for Europe, soil CH₄ sink in temperate forests could be reduced, due to both an increase in the number of flooding episodes in spring and drier summers.
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