Boreal peatland C fluxes under varying permafrost regimes

Abstract

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 CO 2 and CH 4 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 CH 4 fluxes ranged from 0.2 to 14.6 mmol CO 2 m −2 d −1 and from −24 to 344 μmol CH 4, respectively, and differed significantly among peatland types and sampling dates. Our estimates of CH 4 flux are low compared to previous estimates from boreal wetlands, with net consumption of CH 4 typically in frost mounds. Permafrost melt in our study area is associated with 1.6- and 30-fold increases in CO 2 and CH 4 emissions, respectively. More widespread thaw across the discontinuous permafrost region will be an important consideration to boreal C budgets with future climatic changes.