Improving Our Response to Invasive Insects in Order to Protect the Health of Our Forests

At present, there are around 400 species of invasive insects that have been imported to the United States from across the globe (Lovett et al., 2016). This number continues to grow by 2-3 new invasive species every year as a result of international trade (Lovett et al., 2016). Some of these insects selectively target and kill specific tree species in order to survive and persist. As a result, invasive insects have proven to be the only disturbance capable of extirpating tree species, and sometimes entire genera, from their native ranges within decades (Lovett et al., 2016). Historically, the human response to such an invasion often entails harvesting any and all trees that would otherwise be afflicted with insects, a practice called salvage logging (Smith et al., 1997).

In this study, we aimed to forecast the relative impacts that both new (i.e. resistance, resilience, transition) and old (i.e. salvage logging, high grading) would have on the aboveground biomass and species composition of a simulated forest landscape when managed after insect invasion. Although there are many species of invasive insects in the Northeast, we elected to focus on two: the emerald ash borer and the hemlock woolly adelgid. To forecast the impacts of these insects and the various harvesting responses, we used a forest landscape model to apply a pest infestation and each harvest treatment to an identical starting forest. We then let the forest recover and compared the effects of each harvest based on the differences in recovery.