Post-fire ecohydrological conditions at peatland margins in different hydrogeological settings of the Boreal Plain

M. C. Lukenbach, Kelly Jean Hokanson, K. J. Devito, Nicholas Kettridge, R. M. Petrone, Carl Mendoza, Gustaf Granath, James Michael Waddington

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17 Citations (Scopus)
187 Downloads (Pure)

Abstract

In the Boreal Plain of Canada, the margins of peatland ecosystems that regulate solute and nutrient fluxes between peatlands and adjacent mineral uplands are prone to deep peat burning. Whether post-fire carbon accumulation is able to offset large carbon losses associated with the deep burning at peatland margins is unknown. For this reason, we examined how post-fire hydrological conditions (i.e. water table depth and periodicity, soil tension, and surface moisture content) and depth of burn were associated with moss recolonization at the peatland margins of three sites. We then interpreted these findings using a hydrogeological systems approach, given the importance of groundwater in
determining conditions in the soil-plant-atmosphere continuum in peatlands. Peatland margins dominated by local groundwater flow from adjacent peatland middles were characterized by dynamic hydrological conditions that, when coupled with lowered peatland margin surface elevations due to deep burning, produced two common hydrological states: 1) flooding during wet periods and 2) rapid water table declines during dry periods. These dynamic hydrological states were unfavorable to peatland moss recolonization and bryophytes typical of post-fire recovery in mineral uplands became established. In contrast, at a peatland margin where post-fire hydrological conditions were moderated by larger-scale groundwater flow, flooding and rapid water table declines were infrequent and, subsequently, greater peatland-dwelling moss recolonization was observed. We argue that peatland margins poorly connected to largerscale
groundwater flow are not only prone to deep burning but also lags in post-fire moss recovery. Consequently, an associated reduction in post-fire peat accumulation may occur 3 and negatively affect the net carbon sink status and ecohydrological and biogeochemical function of these peatlands.
Original languageEnglish
Pages (from-to)741-753
JournalJournal of Hydrology
Volume548
Early online date18 Mar 2017
DOIs
Publication statusPublished - 1 May 2017

Keywords

  • Wildfire
  • Peatland
  • Moss
  • Groundwater
  • Hydrogeology
  • Margin

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