Resistant tree or resilient ecosystem? Forest insects and pathogens in longleaf pine

Longleaf pine forests once dominated the southern United States coastal plain. Massive conversion to other uses has led to only about 4% of this biologically diverse, productive ecosystem remaining. Current efforts to restore and reestablish longleaf on the landscape have renewed interest in its resistance and resilience to disturbances both abiotic (hurricanes, drought) and biotic (bark and root beetles and their associated fungi). We have conducted a number of experiments looking at aspects of these trees and the woodlands they grow in with regards to insects, pathogens, and a recent hurricane (Michael). The longleaf pine forest we studied, the 12,000 ha Jones Center at Ichauway, saw 20% overall knockdown of trees after the 2018 Hurricane Michael. Immediate and extensive salvage logging, followed by controlled burning saw sitewide, but highly variable, increases in numbers of bark and root feeding beetles. These incredible numbers of tree colonizing beetles post hurricane led to little to no tree mortality. We also characterized insect response to simulated lightning strike. In the process we identified new patterns and new pathogenic fungi. We review our findings within the context of literature on tree defenses in longleaf pine and the dynamics of insect attack of trees in an open canopy, frequent fire system.