Experimental soil warming effects on CO 2 and CH 4 flux from a low elevation spruce–fir forest soil in Maine, USA

Abstract

The effect of soil warming on CO 2 and CH 4 flux from a spruce–fir forest soil was evaluated at the Howland Integrated Forest Study site in Maine, USA from 1993 to 1995. Elevated soil temperatures (∼5 °C) were maintained during the snow‐free season (May – November) in replicated 15 × 15‐m plots using electric cables buried 1–2 cm below the soil surface; replicated unheated plots served as the control. CO 2 evolution from the soil surface and soil air CO 2 concentrations both showed clear seasonal trends and significant ( P 2 flux from the heated plots compared to the controls. No significant differences were observed between heated and control plot soil air CO 2 concentrations which we attribute to rapid equilibration with the atmosphere in the O horizon and minimal treatment effects in the B horizon. Methane fluxes were highly variable and showed no consistent trends with treatment.

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