The role of trunk decay and litter accumulation in determining fire susceptibility in Persian Oak forests

Abstract

Fire in dry and semi-dry areas, like Persian Oak (Quercus brantii) forests, plays a big role in changing ecosystems. Trunk decay and the buildup of dead plant material (litter) affect how fires behave, but exactly how they influence fire damage is not fully understood. This study looks at how trunk decay and litter buildup relate to fire severity in Persian Oak forests, focusing on differences between north- and south-facing slopes. We surveyed three burned sites in the Zagros forests, sampling 120 oak trees across north and south slopes. We collected data on tree size (diameter, height, crown), trunk health (decay, burn marks), and litter around the trunk (within one meter). Statistical tests examined how these factors relate to fire severity. Trees on north-facing slopes showed more severe fire damage than those on south-facing slopes. Trees with cavities had 47% higher burn severity, 44% taller burn marks, and 68% larger burn areas compared to healthy trees. Litter buildup around trees significantly increased fire severity; 88% of trees surrounded by heavy litter had trunk burns. Trunk decay and litter buildup are key factors driving fire severity in Persian Oak forests. Fire intensity is notably higher for trees with cavities and those surrounded by lots of litter, especially on north-facing slopes. Forest management should focus on reducing litter buildup and monitoring trunk decay to lower fire risk. Preventive actions like controlled burns and targeted removal of litter can help decrease fire severity and improve forest resilience.