Physiognomy and Structure: No Data Available

Floristics: Relatively undisturbed second-growth stands generally have a closed (80-100% cover) canopy of tall (>28 m), well-formed trees, the largest with dbh >50 cm and occasionally >80 cm. Canopy composition is mixed and variable, but either Acer saccharum var. saccharum or Acer nigrum, or both, are consistently important and characteristic. Carya cordiformis, Celtis occidentalis, Fraxinus americana, Liriodendron tulipifera, Quercus muehlenbergii, Quercus rubra, Tilia americana, and Ulmus rubra are frequent canopy associates. From the James River south, Aesculus flava is a frequent canopy associate. A sparse (30-40% cover) understory layer of trees 15-20 m tall contains smaller representatives of the canopy trees, especially the two Acer species. Cover in the vertical strata below 15 m is usually very sparse. The most typical and abundant shrub layer species are Asimina triloba and Lindera benzoin, with shrub layers usually somewhat to very open (mean stratum cover = 35%). The herb layer is dense (>80% cover) and contains a number of leafy early-flowering species, among the most abundant of which are Jeffersonia diphylla, Hydrophyllum canadense, and Caulophyllum thalictroides. Somewhat more delicate spring ephemerals that are frequent to locally abundant include Chaerophyllum procumbens var. procumbens, Delphinium tricorne, Dicentra canadensis, Dicentra cucullaria, Erigenia bulbosa, Erythronium americanum ssp. americanum, Floerkea proserpinacoides, Mertensia virginica, Phlox divaricata, Sanguinaria canadensis, and Trillium sessile. Additional characteristic herbs are Asarum canadense, Carex albursina, Carex jamesii, Cystopteris protrusa, Hydrophyllum virginianum, Impatiens pallida, Osmorhiza claytonii, Osmorhiza longistylis, and Viola pubescens var. scabriuscula (= Viola pubescens var. leiocarpon). The exotics Alliaria petiolata, Veronica hederifolia, and Stellaria media, along with the weedy native Galium aparine, are aggressive and problematic invaders of this vegetation type, even in undisturbed stands. Herbaceous layers of this community typically exhibit strong patch dominance and pronounced seasonal aspects. Although the constancies of dominants in sampled stands are very high, observations indicate that Jeffersonia diphylla, Hydrophyllum canadense, and other species may be abundant in some stands and absent from others. Herbaceous growth and flowering begins early and reaches maximal diversity in mid to late spring, after which many species begin to die back with the onset of summer temperatures and full canopy closure. As a result the late-summer aspect of these herbaceous layers is one of low cover and depauperate floristics, a stark contrast to the lush and vibrant aspect of spring (Fleming 1999).

Dynamics:  All of the sampled stands have largely recovered from logging in the distant past. Recent and current disturbances documented in plot sampling included excessive deer browse and invasive exotic weeds. Because of its locations adjacent to frequently flooded stream and river bottoms, which serve as migration corridors for many weedy plants, this association is particularly prone to degradation by nutrient-demanding, shade-tolerant exotics. Observations indicate that Dicentra spp. and Trillium sessile are particularly favored by grazing deer, while Caulophyllum thalictroides, Delphinium tricorne, Hydrophyllum spp., Jeffersonia diphylla are rarely, if ever, grazed. Reduction of native herb cover by deer probably promotes the establishment and abundance of the unpalatable, noxious weed Alliaria petiolata, perhaps the most serious exotic threat to native vegetation in these habitats (Fleming 1999).