include (in order of importance) : tulip poplar ( Lirio- 

 dendron tulipifera ) , red maple ( Acer rubrum ) , green ash 

 ( Fraxinus pennsylvanica ) , American elm ( Ulmus americana ) , 

 sweetgum ( Liguidambar styraciflua ) , shagbark hickory 

 ( Carya ovata) , and swamp blackgum (Nyssa sylvatica var. 

 biflora ) . Scattered throughout the slightly higher, 

 better drained areas are large beech ( Fagus grandifolia ) . 



In general, swamp chestnut and cherrybark oaks along 

 with loblolly pine are more common on the slightly better 

 drained areas of the tract and laurel oak, green ash, and 

 American elm are more frequent in the lower, more poorly 

 drained areas. There is no subcanopy layer. A tall shrub 

 zone dominated by ironwood is present throughout much of 

 the natural area although pawpaw ( Asimina triloba ) , and 

 spicebush ( Lindera benzoin ) are locally common. There is 

 much variation in dominance of the ground cover. The higher 

 areas are dominated by spanglegrass ( Uniola sessiliflora ) or 

 in some areas by giant cane ( Arundinaria gigantea ) . Other 

 slightly wetter sites are dominated by various sedges ( Carex 

 spp.) or by lizard's tail. There appears also to be some 

 seasonal variation in ground cover dominance. Lizard's 

 tail and spanglegrass form dense colonies during the late 

 summer but are much less abundant during the early part 

 of the growing season. 



Vines are common throughout the natural area. Common 

 species include cross-vine ( Anisostichus capreolata ) , 

 trumpet creeper ( Camps is radicans ) , rattan vine ( Berchemia 

 scandens ) , grape ( Vitis sp.) , and climbing hydrangea ( Decum- 

 aria barbara ) . 



The canopy is .essentially closed although numerous wind- 

 thrown trees provide openings. Canopy height ranges from 

 75-90 feet and individual crowns of the oaks are character- 

 istically broad and expansive, a common condition in old- 

 growth hardwood stands. Consequently, the individual trees 

 are rather widely spaced. In one area sampled there was an 

 average of 100 canopy trees per acre. The average dbh (diam- 

 eter at breast height) of the stands varies considerably. In 

 the mature, climax stands along US 264, the average dbh is 20 

 inches although there are many scattered old-growth trees much 

 larger. Some of the maximum dbh's measured were: green ash 

 (38 inches) , swamp chestnut oak (51 inches) , cherrybark oak 

 (45 inches), and laurel oak (66.5 inches). 



The understory layer of ironwood is essentially open. 

 The low density of shrubs and canopy transgressives gives 

 the area an open, park-like aspect. 



161 



