Fire severity functions — fire

Functions to estimate fire effects on foliage, buds and cambium, based on the model by Michaletz & Johnson (2008)

fire_plumeTemperature(Ib_surf, z, T_air = 25, rho_air = 1.169)

fire_barkThermalDiffusivity(fmc_bark, rho_bark = 500, T_air = 25)

fire_radialBoleNecrosis(
  Ib_surf,
  t_res,
  bark_diffusivity,
  T_air = 25,
  rho_air = 1.169,
  T_necrosis = 60
)

fire_leafThermalFactor(SLA, h = 130, c = 2500)

fire_necrosisCriticalTemperature(
  t_res,
  thermal_factor,
  T_air = 25,
  T_necrosis = 60
)

fire_necrosisHeight(
  Ib_surf,
  t_res,
  thermal_factor,
  T_air = 25,
  rho_air = 1.169,
  T_necrosis = 60
)

Arguments

Ib_surf: Surface fireline intensity (kW/m).
z: height (m).
T_air: Air temperature (degrees Celsius).
rho_air: Air density (kg/m3).
fmc_bark: Bark moisture content (% dry weight).
rho_bark: Bark density (kg/m3).
t_res: fire residence time (seconds).
bark_diffusivity: Bark thermal diffusivity (m2/s).
T_necrosis: Temperature of tissue necrosis (degrees Celsius).
SLA: Specific leaf area (m2/kg).
h: Heat transfer coefficient
c: Specific heat capacity
thermal_factor: Tissue thermal factor.

Value

Function fire_plumeTemperature returns the plume temperature at a given height.
Function fire_barkThermalDiffusivity returns the bark thermal diffusivity given a bark moisture value.
Function fire_radialBoleNecrosis returns the depth of radial bole necrosis in cm.
Function fire_leafThermalFactor returns the thermal factor of leaves as a function of specific leaf area.
Function fire_necrosisCriticalTemperature returns the (plume) temperature yielding necrosis for a given residence time and tissue thermal factor.
Function fire_necrosisHeight returns the height (in m) of necrosis for tissues with given thermal factor.

References

Michaletz, S.T., and Johnson, E.A. 2006. A heat transfer model of crown scorch in forest fires. Can. J. For. Res. 36: 2839–2851. doi:10.1139/X06-158.

Michaletz ST, Johnson EA. 2008. A biophysical process model of tree mortality in surface fires. Canadian Journal of Forest Research 38: 2013–2029.