Southern Appalachian Ridgetop Pine Forest

This system consists of predominantly evergreen woodlands (or more rarely forests) occupying very exposed, convex, often rocky south- and west-facing slopes, ridge spurs, crests, and clifftops in the Central Appalachians, Southern Ridge and Valley and Southern Blue Ridge. They occur at moderate to upper elevations (450-1200 m [1500-4000 feet]), with the more southerly examples at the higher elevations. In the Southern Blue Ridge, this system is best developed above 700 m (2300 feet) in elevation. The underlying rock is acidic and sedimentary or metasedimentary (e.g., quartzites, sandstones and shales). The soils are very infertile, shallow and droughty. A thick, poorly decomposed duff layer, along with dead wood and highly volatile ericaceous shrubs, creates a strongly fire-prone habitat. Most examples are dominated by Pinus pungens, often with Pinus rigida and/or Pinus virginiana, and occasionally Tsuga caroliniana. The canopy is usually patchy to open, but areas of closed canopy may be present, especially where Tsuga caroliniana is prominent. Fire is a very important ecological process in this system. Pines may be able to maintain dominance due to edaphic conditions, such as very shallow soil or extreme exposure in some areas which can produce sustained drought conditions, but most sites appear eventually to succeed to oak dominance in the absence of fire. Fire is also presumably a strong influence on vegetation structure, producing a more open woodland canopy structure and more herbaceous ground cover.

Vegetation consists of open forests or woodlands dominated by Pinus pungens, often with Pinus rigida or less commonly Tsuga caroliniana, and sometimes with Pinus virginiana or rarely Pinus echinata codominant. In examples that have not had fire in a long time, Quercus montana (= Quercus prinus), Quercus coccinea, or other oaks are usually present and are sometimes abundant, as are Nyssa sylvatica and Acer rubrum. Castanea dentata may also have once been abundant. A dense heath shrub layer is almost always present. Kalmia latifolia is the most typical dominant, but species of Rhododendron, Vaccinium, or Gaylussacia may be dominant. Herbs are usually sparse but probably were more abundant and shrubs less dense when fires occurred more frequently.

This system occurs on ridgetops, usually only on the sharpest and narrowest spur ridges, and adjacent convex upper slopes. These sites are the extreme of convex landforms. Rapid drainage of rainfall and exposure to wind, sun and lightning are probably the important characteristics. Bedrock may be of any acidic type, including felsic igneous and metamorphic rocks, sandstone and quartzite. Soils are shallow and rocky residual soils. Fire appears to be an important factor.

Fire is apparently a very important process in this system (Harrod and White 1999). Pines may be able to maintain dominance due to shallow soils and extreme exposure in some areas, but most sites appear eventually to succeed to oak dominance in the absence of fire. Fire is also presumably a strong influence on vegetation structure, producing a more open woodland canopy structure and more herbaceous ground cover. Occurrence in highly exposed sites may make this system more prone to ignition, but most fires probably spread from adjacent oak forests. Fires could be expected to show more extreme behavior in this system than in oaks forests under similar conditions, due to the flammability of the vegetation and the dry, windy and steep location. Both high-intensity fires and lower-intensity fires probably occurred naturally. Natural stands probably include both even-aged and uneven-aged canopies.

Southern pine beetle outbreaks are an important disturbance in this system, at least under present conditions. Beetle outbreaks can kill all the pines without creating the conditions for the pines to regenerate. If the pines are lost, the distinction between this system and Southern Appalachian Oak Forest (CES202.886) or Central Appalachian Pine-Oak Rocky Woodland (CES202.600) becomes blurred.

This system is centered on the Southern Blue Ridge, from northern Georgia and South Carolina north through Virginia, with outlying occurrences north through the Central Appalachians to a small incursion in the northern Blue Ridge of south-central Pennsylvania.