Production of methane and carbon dioxide in peatland ecosystems across North America: Effects of temperature, aeration, and organic chemistry of peat

Abstract

Peat soil from 12 northern peatlands, spanning broad gradients in mean annual temperature (MAT), mean annual precipitation (MAP), and plant species composition, was incubated in vitro at differing temperature (2, 12, 22°C), aeration (anoxic, oxic), and with or without added glucose to evaluate controls on potential production of CH4 and CO2 (and CH4 consumption). Methane production and CH4 consumption (at 12°C) were significantly higher in open (nonforested) than forested peatlands, and varied as a function of MAT at each site, with maximum CH4 production (>450 nmol g‐1 d‐1) and minimum CH4 consumption (‐0.03 h‐1 g‐1) at intermediate MAT (i.e., CH4 production <200 nmol g‐1 d‐1 and CH4 consumption ‐0.06 h‐1 g‐1 at lower and higher MAT). Differences in lignin chemistry of the peat helped explain the variation in CH4 cycling: Added glucose stimulated CH4 production, but only in lignin‐rich peat. Carbon dioxide production (10–60 μmol g‐1 d‐1 at 12°C) showed a strong negative relationship with MAT and with the amount and type of lignin in the peat, which increased with decreasing MAT of the site. The results demonstrated complex ways in which temperature affected production of CH4 and CO2 (and CH4 consumption), attributed to differences in organic chemical composition of peat.