Short-term effects of thinning, clear-cutting and stump harvesting on methane exchange in a boreal forest

摘要

Forest management practices can alter soil conditions, affecting theconsumption and production processes that control soil methane (CH₄)exchange. We studied the short-term effects of thinning, clear-cutting andstump harvesting on the CH₄ exchange between soil and atmosphere at aboreal forest site in central Sweden, using an undisturbed plot as thecontrol. Chambers in combination with a high-precision laser gas analyserwere used for continuous measurements. Both the undisturbed plot and thethinned plot were net sinks of CH₄, whereas the clear-cut plot and thestump harvested plot were net CH₄ sources. The CH₄ uptake at thethinned plot was reduced in comparison to the undisturbed plot. The shiftfrom sink to source at the clear-cut and stump harvested plots was probablydue to a rise in the water table and an increase in soil moisture, leading tolower gas diffusivity and more reduced conditions, which favour CH₄production by archea. Reduced evapotranspiration after harvesting leads towetter soils, decreased CH₄ consumption and increased CH₄production, and should be accounted for in the CH₄ budget of managedforests.