Fort Indiantown Gap Macrosite

This site is a valley located between Blue Mountain and Second Mountain on both sides of the Dauphin/Lebanon county line. Historically, parts of the valley were kept open by wildfires and other disturbance. In recent times, the valley has been used as a military reservation. Bombing and other exercises by the military have maintained an unusual, prairie-like habitat in parts of the valley. Currently the Fort is a mosaic of second-growth mixed oak and conifer forests, woodlands, open areas dominated by little bluestem and other grasses, goldenrods, milkweeds, asters, and blueberries. Surveys in 1999 revealed a population of the state-threatened American holly (Ilex opaca) located in St. Pauls Cemetery Woods. This species is found in mixed-hardwood habitat and appears healthy despite evidence of repeated deer browse. Also located in 1999 in the Lebanon County portion of the site was a small population of the forked chickweed (Paronychia fastigiata var. nuttallii) surviving in an area of frequent disturbance from military operations.

This site includes the Woods, an upland forest growing on a well-drained soil on the east side of Manada Creek. Another population of the state-threatened American holly (Ilex opaca) occurs at this portion of the site. Associated tree and shrub species are red oak (Quercus rubra), white oak (Q. alba), red maple (Acer rubrum), black-gum (Nyssa sylvatica), eastern hemlock (Tsuga canadensis), witch-hazel (Hamamelis virginiana), serviceberry (Amelanchier sp.), highbush blueberry (Vaccinium corymbosum), and mountain laurel (Kalmia latifolia).

Evidence of the state-threatened Allegheny woodrat (Neotoma magister) was found in this area during surveys in 1999 and was confirmed again more recently in 2002. Evidence of extant populations was found at 10 locations along Second Mountain, including areas within the Fort Indiantown Gap site and extending into Lebanon County. This species utilizes rocky outcrops along the ridgetop.

Populations of three rare species occur together in the open habitats within the Fort. Associated with old field habitats and early successional habitats are the Leonard’s skipper (Hesperia leonardus), and two additional species of concern not named at the request of the agencies overseeing their protection.

An individual northern myotis (Myotis septentrionalis) was captured within the training center, but the relationship of this location to a maternity site or roost is unknown. A survey of nocturnal insects with blacklight traps yielded several rare species. A handmaid moth (Datana ranaeceps) was the first documented occurrence in in many decades. The host plant for this moth appears to be maleberry (Lyonia ligustrina); it was found in woods adjacent to a large disturbed opening. Another moth species of concern, the pine barrens Zale moth (Zale sp. 1) was located in a wooded area abundant with scrub oak, the host plant for the larval form of the species. The first Pennsylvania record of the earwig scorpionfly (Merope tuber) was also captured in the black lights at Fort Indiantown Gap.

Threats and Disturbances: Some recent human disturbances at Fort Indiantown Gap have benefited the species of concern, while others have eliminated sites for the species. Exotic species, particularly spotted knapweed (Centaurea melitensis), and natural succession to forest are also threats to the habitat and therefore to the listed species.

Conservation Recommendations: The persistence of many of the species of concern in the human-managed habitats of Fort Indiantown Gap depends upon maintaining the primary habitat needs of the species. To do this requires controlling the amount and type of disturbance to the early-successional habitat to favor the survival of the species of concern. The Nature Conservancy is working with the Fort Indiantown Gap National Guard Training Center facility managers to actively manage the habitats and assess how future military operations might coexist with and facilitate the survival of the rare species at this site.