Physiognomy and Structure: No Data Available

Floristics: Physiognomy is variable, ranging from herbaceous with a sparse tree layer, to shrubland, to open savanna-like woodland, to nearly closed-canopy forest along upland edges. Pinus rigida is the typical overstory dominant (5-60% cover), but occasional trees of Acer rubrum, Nyssa sylvatica, and a few other species also occur. Trees are often somewhat stunted and usually <20 m tall. Shrub cover and density often vary within sites and can be locally dense, locally sparse, or form a patch-mosaic with herb-dominated areas. Alnus serrulata, Gaylussacia baccata, Hypericum densiflorum, Ilex verticillata, Kalmia latifolia, Lyonia ligustrina var. ligustrina, Menziesia pilosa, Photinia spp., Rhododendron maximum, and Spiraea tomentosa are characteristic shrubs that occur in various aggregations. Both Alnus serrulata and Hypericum densiflorum may spread into very low (<0.5 m tall) colonies where fire has killed back larger shrubs of these species. Except under dense shrubs, the herb layer is well-developed and dense, containing running vines of Rubus hispidus, high graminoid and fern cover, and moderate cover of forbs. The most frequent herbs among 17 plot samples are Osmunda cinnamomea, Carex stricta, Gaultheria procumbens, Eriophorum virginicum, Carex atlantica ssp. atlantica, and Drosera rotundifolia. Less constant herbaceous species that can be important at some sites include Calamagrostis coarctata, Carex folliculata, Dulichium arundinaceum, Glyceria canadensis, Glyceria laxa, Juncus brevicaudatus, Juncus subcaudatus, Maianthemum canadense, Parnassia asarifolia, Rhynchospora capitellata, Thelypteris noveboracensis, Triadenum fraseri, Vaccinium macrocarpon, and Viola macloskeyi ssp. pallens. Several Sphagnum spp. contribute to a dense surficial bryophyte layer. Overall species richness ranges from 20 to 46 taxa per 400 sqm (mean = 31 taxa).

Dynamics:  The development of this community appears to require a very specific set of environmental conditions, which accounts for its rarity in the region. Its ecological dynamics are also complex and require additional study. Charcoal, charred wood and snags, and other evidence of fire are found at most sites. Adjacent upland forests are typically dry oak/heath forests that are susceptible to fires which in some cases have spread into the adjacent valleys. At one of the Virginia sites, extensive sapling pitch pine recruitment had clearly followed one such recent fire event. Pitch pine recruitment has also been documented in West Virginia stands without recent fires. Hydrologic stress from variable inundation levels over time may also play a role in keeping the vegetation open. At sites with deep, quaking peat mats, trees appear to grow extremely slowly and eventually fall or die when their roots can no longer support the trunk and crown weight. Most stands of this vegetation occur in drainages where beavers are (or have been) active, but the relationship is unclear. The possibility that the community could develop on old, reclaimed beaver clearings cannot be discounted. However, the best examples in Virginia occur well away from active beaver clearings, and examples that have suffered recent beaver incursions exhibit a loss of many fastidious herbaceous species and replacement by dense shrub thickets and/or coarse weedy herbs such as Scirpus cyperinus and Leersia oryzoides, possibly indicative of eutrophication. Other disturbances noted at plot-sampling sites include herbivory by white-tailed deer, encroachments by exotics spreading from adjacent clearings or roads, and adjacent logging.