Boreal peatland C fluxes under varying permafrost regimes

Discontinuous permafrost in peatlands has recently been melting across western Canada, creating wet Sphagnum-Carex lawns (internal lawns) interspersed within drier ombrotrophic bog. Permafrost degradation alters peat hydrology, thermal regimes and plant species assemblages, all of which could affect gaseous C emissions in peatlands. We quantified CO2 and CH4 fluxes across the peat-atmosphere boundary using dark static chambers in adjacent internal lawns, continental bogs and frost mounds in an area of localized permafrost in north-central Saskatchewan. Carbon dioxide and CH4 fluxes ranged from 0.2 to 14.6 mmol CO2 m−2 d−1 and from −24 to 344 μmol CH4, respectively, and differed significantly among peatland types and sampling dates. Our estimates of CH4 flux are low compared to previous estimates from boreal wetlands, with net consumption of CH4 typically in frost mounds. Permafrost melt in our study area is associated with 1.6- and 30-fold increases in CO2 and CH4 emissions, respectively. More widespread thaw across the discontinuous permafrost region will be an important consideration to boreal C budgets with future climatic changes.