Fire damage effects on red oak timber product value

• Value loss was tracked on dimensional lumber sawn from fire-damaged red oak trees.
• Fire-scar size, tree size, and time were important value loss predictors.
• Threshold values for scar size and residence time were identified.
• Pole-size trees are most vulnerable to fire-caused value loss.

Land managers use prescribed fire for a variety of resource objectives on sites containing merchantable trees. We analyzed how fire-caused injuries (i.e., fire scars) affect lumber volume and value in 88 red oak (Quercus velutina, Quercus rubra, and Quercus coccinea) butt logs from trees harvested from three sites in southern Missouri. Trees with varying amounts of external fire damage, time since fire, and diameter were harvested and milled into dimensional lumber. We tracked lumber grade changes and volume losses due to fire-related injuries on individual boards (n = 1298, 18.3 cubic meters (7754 board feet)). Most analyses considered value loss to the individual butt log. We identified threshold values for fire-scar height and percent basal circumference injured, beyond which value loss is expected. Our analysis produced two models to describe how butt log value loss relates to fire-scar dimensions and residence time (timespan between damage occurrence and tree harvest). Overall, value and volume losses due to fire damage were low. If fire damage is less than 50 cm in height and 20% of basal circumference, our study suggests little value loss is to be expected within 14 years of injury. If these thresholds are exceeded, value loss is likely, and increases over time. Value loss is very low if trees are harvested within approximately five years after fire damage, regardless of scar size. These findings are applicable for red oak trees which are at least 20 cm diameter at breast height at time of fire damage and with fire-scar residence times not greater than fourteen years.