Overstory tree composition of eastern hemlock stands threatened by the hemlock woolly adelgid at Delaware Water Gap National Recreation Area

We described overstory tree age and composition among hemlock stands that varied in physiographic structure at Delaware Water Gap National Recreation Area located in northeastern Pennsylvania and northwestern New Jersey. Hemlock stands were comprised primarily of eastern hemlock (Tsuga canadensis), chestnut oak (Quercus prinus), black birch (Betula lenta), Eastern white pine (Pinus strobus), and white oak (Quercus alba). Forest stands characterized by steep slopes and high gradients supported the highest basal area of hemlock. Trees within hemlock stands ranged in age from 68.0-148.0 years. These data are valuable because as eastern hemlocks decline throughout the mid-Atlantic region of the United States due to infestation of the exotic insect pest, the hemlock woolly adelgid (Adelges tsugae), hardwood species will likely become more prominent in these stands in the future. The documentation and description of tree composition of a threatened ecosystem prior to its decline is important for future restoration efforts and potential tree replacement in forest stands.