Forests

Together, the forest alliances in Valley Forge NHP make up the largest percentage of park property - approximately 34%. A total of 18 different forest communities have been delineated within the park. In descending order, the largest of these are:

Modified Successional Forest (VAFO-type) – 456 acres
Liriodendrontulipifera [tuliptree] Forest Alliance – 374 acres
Quercusalba [whiteoak] Forest Alliance – 204 acres
Quercusprinus [chestnutoak] Forest Alliance – 186 acres
Platanus-Fraxinus [sycamore-ash] Floodplain Forest – 170 acres

The Modified Successional Forest type, which includes several sub-types, incorporates forests with white ash, black walnut, and American elm. For the less common sub-types, dominant canopy species may also include tree-of-heaven, black locust, eastern red cedar, and oriental bittersweet. Typical subcanopy species include box elder, American elm, flowering dogwood, black cherry, and sassafras. This common forest type is found throughout the park on areas with a history of disturbance such as abandoned farmland and forest gaps (Lundgren, et al. 2002). It is particularly common in the eastern and northern portions of the park where forest cover is more fragmented.

The Liriodendron tulipifera [tuliptree] Forest Alliance is most common in the western portion of the park, south of the Schuylkill River, although it is also found scattered throughout the park. While tuliptree is dominant in many stands, black oak and white ash are co-dominant or sub-dominant in others. Other trees found in this alliance include red maple, red oak, and sassafras. Heavy deer browsing has greatly reduced the shrub layer below 5 feet in height, the height reachable by white-tailed deer. Shrub species included in this forest association include dogwood, spicebush, black haw and mountain laurel; however, they are declining and in many cases missing from this alliance due to the heavy browsing by white-tailed deer (Lundgren, et al. 2002).

The two oak communities, Quercus alba [white oak] Forest Alliance and Quercus prinus [chestnut oak] Forest Alliance, are both found on moderate to steep slopes, making up the predominant forest groups on Mount Misery and Mount Joy. Dominating both alliances are the dry oak species: white oak and chestnut oak. In the Quercus prinus alliance, black gum and scarlet oak may be co-dominants. This list is larger for the Quercus alba alliance: red maple, sweet birch, tuliptree, beech, scarlet oak, and sassafras. The shrub layer for the Quercus prinus alliance is often moderate to dense stands of mountain laurel or young black gum. Typical tall shrubs in the Quercus alba alliance include flowering dogwood, witch hazel, and mountain laurel (Lundgren, et al. 2002). As with other forest alliances within the park, shrub species are declining and in many cases missing from this alliance due to heavy browsing by white-tailed deer.

Located primarily along the floodplain of the Schuylkill River and Valley Creek, the Platanus-Fraxinus [sycamore-ash] Floodplain Forest is characterized by a mix of green ash, sycamore, and silver maple. This community may also have black walnut, box elder, and river birch present. Common species in the subcanopy include green ash, box elder, silver maple, and American elm. Shrub species included in this forest association are typically spicebush, multifora rose, and raspberries. Shrub species also are declining and in many cases missing from this alliance due to heavy browsing by white-tailed deer.

Other smaller vegetation alliances found within Valley Forge NHP include Successional Old Fields Pine Plantation, Acer saccharinum [silver maple] Temporarily Flooded Forest Alliance (found only along the northern shore of the Schuylkill River), Mixed White Pine Planted Forest, and Catalpa speciosa Forest.