Physiognomy and Structure: No Data Available

Floristics: Vascular plants are generally absent and lichens dominate. Maximum patch size is about one acre, and many patches are much smaller. Lasallia papulosa and Stereocaulon glaucescens are generally abundant and conspicuous in variable combinations. Although not abundant, Chrysothrix chlorina is a good diagnostic species as it appears to be absent from siliciclastic and granitic boulderfields in this region; it is scattered on sheltered boulder faces and in grottoes, often with Psilolechia lucida, Usnea halei, and Ramalina intermedia. Other minor umbilicate and foliose species include Flavoparmelia baltimorensis, Parmelia sulcata, and Umbilicaria muhlenbergii. Many crustose species occur, including Aspicilia cinerea, Diploschistes scruposus, Fuscidea recensa, Lepraria spp., Porpidia spp., Rhizocarpon rubescens, and Trapeliopsis granulosa. Flat surfaces and interstices that have thin deposits of organic matter often support a variety of fruticose lichens, including Cladonia rangiferina (= Cladina rangiferina), Cladonia stellaris (= Cladina stellaris), Cladonia crispata, Cladonia furcata, Cladonia pleurota, and Cladonia squamosa. At higher elevations, a number of characteristic arctic-boreal lichens occur, including Cladonia coccifera, Melanelia stygia, Microcalicium arenarium, Parmelia omphalodes, Porpidia tuberculosa, Rhizocarpon geographicum, and Lasallia caroliniana (= Umbilicaria caroliniana). Along the edges of the boulderfields, scattered individuals or patches of Polypodium appalachianum, Hylotelephium telephioides, and other vascular plants may occur in transition zones with forests or woodlands.

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. In this region, metabasalt underlies much less acreage than quartzite and sandstone and is less resistant to weathering. Consequently, exposed metabasalt boulderfields are quite rare.