Physiognomy and Structure: No Data Available

Floristics: In Pennsylvania serpentine barrens, the forest or woodland canopy is dominated by Acer rubrum and Quercus alba, as well as other oak species, including Quercus falcata, Quercus rubra, and Quercus velutina. On Staten Island, New York, the canopy includes Betula populifolia and Populus tremuloides in addition to Quercus velutina and Sassafras albidum. The subcanopy is characterized by Acer rubrum, Quercus alba, Nyssa sylvatica, and Prunus serotina. The shrub layer is dominated by Smilax rotundifolia and/or Smilax glauca. Vaccinium pallidum, Rubus allegheniensis, Gaylussacia baccata, Prunus serotina, Morella pensylvanica (= Myrica pensylvanica), Rhus copallinum, and/or Viburnum recognitum may also be present in the shrub layer. The herbaceous layer under the canopy cover is depauperate and typically dominated by Smilax rotundifolia, Smilax glauca, and Microstegium vimineum. Other typical herbaceous species include Danthonia spicata, Carex glaucodea, and Lonicera japonica.

Dynamics:  This plant community is adapted to the weathering of serpentine bedrock. It was once thought that the lack of canopy cover was maintained by the unique edaphic features of the chrome series soils, but in the last 20 years, many sites have been invaded by dense Pinus virginiana (Tyndall 1992a). In Pennsylvania, red maple and white oak are the canopy dominants of this type; while in New York, dominant canopy species include black oak, sassafras, and gray birch. This phenomenon dramatically alters the light regime and promotes substantial soil development (up to 10 cm in 20 years). Under these conditions, an entirely different community develops as the influence of the bedrock is buffered by the soil/litter accumulation. This closed-canopy serpentine forest typically exhibits a dense understory of Smilax rotundifolia. Some of the characteristic herbaceous serpentine species apparently persist in the ground layer as scattered non-flowering individuals; other populations appear to die out but may persist in the seed bank. Selective cutting has been effective in restoring degraded sites to their previous composition and structure, but most researchers believe that without regular burning to prevent soil development the serpentine plant communities will not persist. There is substantial evidence that most of the existing areas were regularly burned by Native Americans (Marye 1920, 1955a, 1955b, 1955c) and perhaps maintained by grazing after European settlement.