Predicting threats to coastal forest ecosystems from the baldcypress leafroller, an emergent pest

Forested coastal wetlands are economically important ecosystems that reduce damage from tropical storms by serving as wind buffers. Climate change is threatening some coastal forests through rises in sea-level and could also increase storm frequency and severity in the gulf coast. An emergent native pest, the baldcypress leafroller (Archips goyerana Kruse), has defoliated thousands of hectares of coastal Louisiana baldcypress (Taxodium distichum (L). Rich.) since the 1980s. Defoliation has been driven by changes in regional hydrology, including saltwater intrusion, and is thus both a cause and symptom of the declining health of coastal forests. Despite the serious effects of this pest – such as reduced radial growth and tree morality - the extent of its native range remains unknown. Using occurrence data for baldcypress leafroller and baldcypress, we developed a species distribution model for the pest throughout the southeastern US. We then linked predictions from that model with (i) basal area of baldcypress forests and (ii) storm surge forecasts to identify baldcypress populations at risk of future leafroller defoliation. We hope that understanding the potential range of baldcypress leafroller will enable forest managers to anticipate outbreaks from this insect and, in areas where this insect occurs, potentially use this species as a bioindicator for ecosystem health.