Carbon dioxide and methane production potentials of peats from natural, harvested and restored sites, eastern Québec, Canada

Abstract

Drainage, vegetation removal and harvesting, and vegetation restoration have a profound effect on carbon cycling in peatlands. Through laboratory incubations of 114 peat samples collected from the surface layer and just above and just below the water table at 13 sites, we examined the potential for carbon dioxide (CO₂) production under aerobic and anaerobic conditions and methane (CH₄) production under anaerobic conditions. CO₂ production rates ranged from 0.04 to 1.05 mg g⁻¹ d⁻¹ under aerobic conditions and 0.01 to 0.29 mg g⁻¹ d⁻¹ under anaerobic conditions. Rates of CO₂ production were generally smallest in the lower parts of the profiles and at the recently restored sites where deep peat was exposed at the surface; they were largest in the freshly-formed surface peat at the undisturbed bog and older restoration sites where a strong cover of vegetation had developed. The CO₂ production potentials were negatively correlated with the Von Post Index of decomposition, and aerobic: anaerobic production ratios averaged 4.3: 1. Largest rates of anaerobic CH₄ production occurred in samples close to the soil surface with fresh peat accumulation and a high water table, and smallest rates were in samples from the subsurface of sites with a low water table. Anaerobic CH₄ production was significantly positively correlated with aerobic and anaerobic CO₂ production. These production potentials show that drainage, harvesting, and restoration change the ability of the peat profile to produce and emit CO₂ and CH₄.