A daily peat moisture code for monitoring and predicting peatland fire danger.

Peatlands, ecosystems with deep (>40 cm) organic soils, play diverging roles in landscape wildfire regimes based on their moisture status. When peatlands are dry they can be the source of high-severity fire and carbon and smoke emissions. The daily Peat Moisture Code (PMC) presented here calculates the change in storage in the peatland water balance and accounts for peatland ecohydrological feedbacks by integrating peat hydrophysical properties using novel equations. Evapotranspiration is modelled using a modified Priestley-Taylor method. The change in water storage is converted to an index (the PMC) that correlates with water table position by accounting for the Specific Yield of peat at different depths and a negative (dampening) feedback on evapotranspiration. The PMC represents the moisture status of peatlands where high PMC values indicate dry fuel conditions driving higher fire danger and high-severity burns. Exemplary fire danger thresholds are presented for the example to assist with interpretation. The PMC is a generic method for quantifying peatland fire danger in varying ecoregions and peatland types. ● Water balance model with daily bookkeeping approach ● Minimal data requirements consistent with federal and provincial weather stations ● Represents the methodological basis for the hourly PMC of the next-generation Canadian Forest Fire Danger Rating System.