Scorch height and volume modeling in prescribed fires: Effects of canopy gaps in Pinus pinaster stands in Southern Europe

Evaluating Crown Scorch Predictions From A Computational Fluid Dynamics Wildland Fire Simulator

“…Using two different canopy heights in the simulation resulted in a step-like function of crown scorch height at between intensities of 550 and 775 kw/m. The effect of canopy structure, particularly canopy base height, was recently identified by Molina et al (2022) and agrees with the simulated results presented here where the lower canopy height results in lower crown scorch height. Nevertheless, the I 2/3 trend was still followed by both canopies, which suggests that while canopy characteristics may change the magnitude of scorch height, the trend between scorch height and I observed by Van Wagner holds at low windspeeds.…”

“…The Van Wagner formulation that links fireline intensity to crown scorch height through buoyant plume theory is confirmed by empirical observations of crown scorch in prescribed and wildfire conditions e.g. (Saveland et al, 1990;Molina et al, 2022). Likewise, winds and fire weather that either drive intensity or effect buoyant plume dynamics are also noted to influence crown damage (Thompson and Spies 2009).…”

“…Buoyant plume dynamics is a first-order process that determines the spatial patterns of heat transfer to the canopy that results in plant tissue damage. However, buoyant plume dynamics are influenced by canopy structure characteristics such as canopy base height and canopy gaps, which also have an observed influence on scorch height or percent scorch (Molina et al, 2022). This suggests that canopy structure, which is not accounted for in Van Wagner's empirical model, likely influences scorch height or percent canopy scorched.…”

Modeling wind adjustment factor in Mediterranean stands of Southern Europe

“…WAF variation implies a change in fire behavior, mainly in spread rate, flame length and fire-line intensity. A change in rate of spread and flame length would promote a higher fire-line intensity (Byram, 1959), and therefore, a higher scorch height and damages to trees (Molina et al, 2022). The wind speed modeling is a very complex phenomenon (Moon et al, 2019).…”

“…Some authors (Gillies et al, 2002) have even proposed differences between species, but they suggested that is not be large enough to have a practical implication. However, a simplified wind profile simulation assumes a constant sub-canopy WAF when canopy gaps and topographical position could increase wind speed due to Venturi effect (Molina et al, 2022). Therefore, WAF could be also affected by wind speed (Moon et al, 2019).…”