Evaluation of hydro-physical properties along a northern boreal bog peatland transect

Abstract Advances in peatland ecohydrological modelling highlight the need for higher resolution depth profiles of important soil physical properties. Peatland soil profiles exist as a continuum from Sphagnum-dominated surface cover to highly decomposed peat at depth. We determined the bulk and particle density, porosity, saturated hydraulic conductivity (Ksat), and von Post in a northern bog to a depth of ~ 200 cm in 5-cm intervals along a transect extending from a moderately treed to a more open area. The bulk and particle densities and von Post scores increased, and porosity decreased with depth. The particle density had a relatively abrupt shift near ~ 75 cm changing from ~ 0.8 g cm− 3 to a relatively consistent ~ 1.4 g cm− 3. The variability measured was small in the upper ~ 25 cm, larger at depths of ~ 25–125 cm, and became more moderate at depths > ~ 125 cm (but not particle density). The variability of bulk density at the deeper depths results in the observed variability of porosity as well. The larger variability in physical properties roughly coincides with the abrupt shift in the magnitude of measured properties suggesting that contemporary processes and/or past events (e.g., wildfire) could be responsible for this pattern. Bulk and particle density and porosity exhibited a relationship with the von Post score with an abrupt shift in values between von Post scores of 3 and 4. Detailed examination of peatland soil properties will improve the robustness and reliability of models and may reveal additional information on the history and processes of formation.