Long-term effects of clear-cutting and selective cutting on soil methane fluxes in a temperate spruce forest in southern Germany

Based on multi-year measurements of CH₄ exchange in sub-daily resolution we show that clear-cutting of a forest in Southern Germany increased soil temperature and moisture and decreased CH₄ uptake. CH₄ uptake in the first year after clear-cutting (−4.5 ± 0.2 μg C m⁻² h⁻¹) was three times lower than during the pre-harvest period (−14.2 ± 1.3 μg C m⁻² h⁻¹). In contrast, selective cutting did not significantly reduce CH₄ uptake. Annual mean uptake rates were −1.18 kg C ha⁻¹ yr⁻¹ (spruce control), −1.16 kg C ha⁻¹ yr⁻¹ (selective cut site) and −0.44 kg C ha⁻¹ yr⁻¹ (clear-cut site), respectively. Substantial seasonal and inter-annual variations in CH₄ fluxes were observed as a result of significant variability of weather conditions, demonstrating the need for long-term measurements. Our findings imply that a stepwise selective cutting instead of clear-cutting may contribute to mitigating global warming by maintaining a high CH₄ uptake capacity of the soil.