M. C. Lukenbach et al.

Abstract Wildfire is the largest disturbance affecting northern peatlands; however, little is known about how burn severity (organic soil depth of burn) alters post‐fire hydrological conditions that control the recovery of keystone peatland mosses (i.e. Sphagnum ). For this reason, we assessed the impact of burn severity on moss water availability by measuring soil tension ( Ψ ) and surface volumetric moisture content ( θ ) in burned and unburned portions of a peatland complex 2 years after fire. We found that both high and low burn severity decreased post‐fire water availability by altering peat hydrophysical properties (moisture retention and water repellency). Locations covered by Sphagnum fuscum prior to fire exhibited a decreasing post‐fire water availability with an increasing burn severity. In contrast, the lowest water availability ( Ψ > 400 cm, θ < 0·02) was observed in feather mosses that underwent low burn severity (residual branches identifiable). Deep burning (>0·20 m) in peatland margins and burn depths >0·05 m in the middle of the peatland exhibited the highest water availability ( Ψ < 60 cm). Locations with low surface θ and high Ψ , notably feather mosses undergoing low burn severity, exhibited minimal moss recolonization. Such areas dominate post‐fire surface cover (~40%) within late successional (mature) peatlands or peatlands located in dry hydrological settings. We argue that such environments are under‐represented in conceptual models of post‐fire recovery. A new conceptual model is proposed in which (1) deep burning is counterbalanced by rapid recolonization and (2) pre‐fire species interact with burn severity to produce substantial lags in post‐fire moss recovery. Copyright © 2015 John Wiley & Sons, Ltd.