A Decision-Support System to Help Manage Forest Tent Caterpillar Defoliation

Forest tent caterpillar is one of the most important defoliators of northern hardwood forests. The northeastern states are now experiencing the largest outbreak to occur in the last half-century. Following severe defoliation, some stands suffer significant mortality and dieback, while others do not. The causes of this spatial variation in susceptibility to damage are not well understood. A decision-support system predicting tree susceptibility to dieback and mortality will allow users to better plan for intervention and recovery in this and future outbreak events.

NSRC researchers will identify factors that can predict forest susceptibility to dieback and mortality following defoliation. They will make measurements in 60 study sites in New York, Vermont, Massachusetts, and New Hampshire, including 40 sites previously studied under the North American Maple Project. They will evaluate patterns of soil moisture and chemistry, forest structure, and defoliation intensity and duration as predictors of observed patterns of forest damage. They will also assemble data layers that make it possible to predict the risk of forest decline over the region, using a regression model developed from the study sites. Landscape level prediction is attainable for the first time with this outbreak because of advances in geo-referenced aerial mapping of defoliation over extensive areas.

The predictive model will form the basis for a decision-support system predicting forest susceptibility to immediate mortality and long-term decline following defoliation by forest tent caterpillar. The decision support system will be available on a website, hosted by the NYSDEC. Potential users include foresters, landowners, sugarbush operators, and community forest managers, in addition to state and academic groups.