Physiognomy and Structure: No Data Available

Floristics: On the largest occurrences, vascular plants are generally absent and lichens dominate. Maximum patch size is about ten acres, but most patches are considerably smaller. Lasallia papulosa and Lasallia pensylvanica, either singly or in combination, are generally abundant and conspicuous. Dimelaena oreina abundantly covers many dry, exposed rock surfaces that are not covered with Lasallia spp. and larger foliose lichens. Although of scattered occurrence, Melanelia culbersonii has been found across the full elevation range of the type and is a good diagnostic species, as it appears to be restricted mostly to siliciclastic rocks (and occasionally coarse-grained, quartz-rich granites that are nearly devoid of dark minerals) in this region. Other minor umbilicate and foliose species include Hypogymnia physodes, Physcia subtilis, Umbilicaria muhlenbergii, Xanthoparmelia conspersa, and Xanthoparmelia plittii. Many crustose species occur, including Aspicilia cinerea, Fuscidea recensa, Lecanora spp., Lepraria spp., Rhizocarpon reductum, and Sarcogyne clavus. Flat surfaces and interstices that have thin deposits of organic matter often support a variety of fruticose lichens, including Cladonia rangiferina (= Cladina rangiferina), Cladonia uncialis (= Cladina uncialis), Cladonia crispata, Cladonia macilenta, Cladonia ochrochlora, and Cladonia squamosa. In the upper elevation range, boreal lichens such as Melanelia stygia and Arctoparmelia centrifuga are present, but they are not abundant. Along the edges of the boulderfields, scattered individuals of Parthenocissus quinquefolia, Vaccinium spp., and other vascular plants may occur in transition zones with forests or woodlands. Smaller, more marginal occurrences frequently have sparse vascular plant cover, primarily stunted trees of Betula lenta, Sassafras albidum, Quercus montana (= Quercus prinus), Quercus coccinea, Quercus velutina, Carya glabra, and Carya ovalis. Widely scattered shrubs may include Kalmia latifolia and other ericads. Herbs are usually absent, but Dicentra eximia is known from some occurrences.

Dynamics:  The exposed rock surfaces supporting this community are subject to fluctuating, daily extremes of temperature, humidity, and moisture saturation during the growing season, as well as to low temperatures, high winds, and frequent ice during the winter. Boulderfield habitats have resulted from periglacial phenomena and the collapse of resistant strata from weathering and erosion of weaker underlying rocks. Most Central Appalachian boulderfields are well-weathered and now support woodland or forest vegetation. Relatively few remain fully exposed and support wholly nonvascular communities.