OOS 32-3 - Assessing damage vulnerability and pest impacts resulting from Hurricane Michael in intensively managed forests

Intensively managed forests have unique vulnerabilities to damage from major hurricanes and other wind events, including tendency toward even-age classes and low tree species diversity, which can increase the potential for broad-scale damage compared to stands with a diversity of species and age classes. While hurricane damage is part of the natural disturbance regime of southern U.S. coastal plain forests, there is concern that the increasing frequency and intensity of storms resulting from climate changes will lead to greater impacts from pests and pathogens, as well as increasing costs for landowners associated with timber loss and reforestation efforts. Understanding how intensive forest management interacts with wind damage from hurricane events, as well as how pest species may respond to damage, is important for continued sustainable management of forests, facilitation of risk management planning, and implementation of risk mitigation measures. Here, utilizing post-damage data collected from land managers in southern Alabama, the Florida panhandle, and southern Georgia before and after Hurricane Michael, we examined how forest stand age class, dominant tree height, planting density, tree species, and prior management activity predict windthrow damage vulnerability. Additionally, we conducted surveys of bark beetles, root-feeding weevils, and wood boring beetles across two years after the storm to examine how populations respond to differing damage levels. Stands with dominant heights >14 m, trees per acre <600 (trees per hectare <1,483), and within 50 km of the coast were the most likely to experience severe damage. Wetter soils and recent thinning also contributed to increased vulnerability to severe damage. Bark beetles and root feeding weevils did not show a relationship with damage level one to two years post-storm, but wood boring beetles including Monochamus sp. were 60% higher in moderately damaged stands one year post-storm, and total catches of wood boring beetles increased by 29% two years after the storm. These results suggest that higher density planting in areas nearer the coast and in wetter soils may reduce damage potential, and salvage logging within one year after a storm event in moderately damaged areas may be necessary to reduce pest pressure from wood boring beetles.