Invalid Unit Specified
G162 Pinus virginiana - Pinus pungens - Pinus rigida Woodland & Barrens Group

The U.S. National
Vegetation Classification
Type Concept Sentence: This vegetation encompasses predominantly evergreen woodlands and forests dominated by Pinus pungens, often with Pinus rigida and/or Pinus virginiana, and occasionally Tsuga caroliniana, occupying very exposed, convex, rocky south- and west-facing slopes and related habitats in the Central Appalachians, Southern Ridge and Valley and Southern Blue Ridge, including distinctive shale barrens of low to mid elevations in the Central and Southern Appalachians.
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Common (Translated Scientific) Name: Virginia Pine - Table Mountain Pine - Pitch Pine Woodland & Barrens Group
Colloquial Name: Virginia Pine - Table Mountain Pine Woodland & Barrens
Hierarchy Level: Group
Type Concept: Vegetation of this group encompasses predominantly evergreen woodlands and 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, as well as distinctive shale barrens of low to mid elevations in the Central and Southern Appalachians. They typically 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 group is best developed above 700 m (2300 feet) in elevation, but some examples may be found at lower elevations. 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, or where fire has been absent. The shrub layer may be well-developed, with Gaylussacia baccata, Vaccinium pallidum, or other acid-tolerant species most characteristic. Herbs are usually sparse but may include Pityopsis graminifolia and Tephrosia virginiana. Fire is a very important ecological process in this group. Frequent, low-intensity fires coupled with periodic severe fires is one factor that determines the occurrence of this vegetation rather than hardwood forests under natural conditions. The 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.

In floristically distinctive shale barrens examples, the exposed aspects, parent material with high levels of toxic metals, and lack of soil create extreme conditions for plant growth. Vegetation is mostly of a woodland physiognomy, but may include large open areas of sparse vegetation. The dominant trees are primarily Quercus prinus and Pinus virginiana. On higher-pH shale barrens, which are less common, the primary trees include Juniperus virginiana and Fraxinus americana, but these are placed in a different group. Shale barrens endemics are diagnostic in the herb layer. The substrate includes areas of solid rock as well as unstable areas of shale scree, usually steeply sloped. The fully exposed areas are extremely dry. These barrens are high in endemic species.
Diagnostic Characteristics: Stands have an open to moderately dense canopy of Pinus pungens, often with Pinus rigida and/or Pinus virginiana. In addition, Quercus prinus may be a component. In some cases, Pinus pungens may be absent and Pinus virginiana (in a setting other than ruderal reverting lands) will be the dominant. The understory may vary from open with grasses to densely shrubby with ericads. In addition, stands dominated by Tsuga caroliniana are included here.
Rationale for Nominal Species or Physiognomic Features: Stands with Pinus pungens are "core" to the concept of this group, but it includes other types (slightly) outside of the range of Pinus pungens and instead with Pinus rigida and/or Pinus virginiana. It also includes stands dominated by Tsuga caroliniana and open-canopy pine stands associated with ultra-mafic serpentine barrens.
Classification Comments: There may be some conceptual overlap with some associations in Shortleaf Pine - Oak Forest & Woodland Group (G012), particularly in terms of Pinus virginiana ingrowth into Pinus echinata stands following the decline of Pinus echinata due to impacts of southern pine beetle and lack of fire. Sites that would support this vegetation under a natural fire regime, but which have lost the pines by logging, southern pine beetle or senescence in the absence of fire, should probably be regarded as degraded examples of this type. However, they become virtually indistinguishable from related deciduous or mixed forests over time.
Similar NVC Types:
G012 Shortleaf Pine - Oak Forest & Woodland, note:
Physiognomy and Structure: Vegetation is mostly of a woodland physiognomy, but may include large open areas of sparse vegetation. The canopy is usually patchy to open, but areas of closed canopy may be present. The understory and shrub layer may vary from open with grasses to densely shrubby; herbs are usually sparse.
Floristics: Vegetation of this group generally consists of open forests or woodlands dominated by some combination of Pinus virginiana (or rarely Pinus echinata), with Pinus rigida or with Pinus pungens, or less commonly Tsuga caroliniana. In examples in which fire has not been present in a long time, Quercus coccinea, Quercus prinus, or other oaks may be present and are sometimes abundant, as are Acer rubrum and Nyssa sylvatica. Castanea dentata may also have once been abundant. A dense heath shrub layer is almost always present. Kalmia latifolia is the most typical dominant shrub, but species of Gaylussacia, Rhododendron, and/or Vaccinium may be present to dominant. Herbs are usually sparse but probably were more abundant and shrubs less dense when fires occurred more frequently. Following long periods without fire, most stands have increased densities of Kalmia latifolia and Quercus spp. as well as Acer rubrum and Pinus strobus (Welch and Waldrup 2001).

In the more specific case of Central Appalachian shale barrens (which are included here and are of major conservation significance), stunted trees, including Carya glabra, Pinus virginiana, and Quercus prinus, are common. They are strongly characterized by their open physiognomy and by a suite of uncommon and rare plants found almost exclusively in these habitats (Fleming et al. 2004). Endemic or near-endemic shale barren species include Arabis serotina, Clematis albicoma, Clematis viticaulis and also endemic to Virginia, Eriogonum allenii, Oenothera argillicola, Packera antennariifolia, and Trifolium virginicum. Other more-or-less widespread and characteristic herbaceous species of shale barrens include Antennaria virginica, Blephilia ciliata, Brickellia eupatorioides var. eupatorioides, Carex pensylvanica, Danthonia spicata, Deschampsia flexuosa var. flexuosa, Erysimum capitatum var. capitatum, Helianthus laevigatus, Paronychia montana, Phlox subulata, Potentilla canadensis, Selaginella rupestris, and Schizachyrium scoparium.
Dynamics: Fire is apparently a very important process influencing the vegetation of this group (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 vegetation more prone to ignition, but most fires probably spread from adjacent oak forests. Fires could be expected to show more extreme behavior than in oak forests under similar conditions, due to the flammability of the vegetation and the frequently dry, windy conditions and steep location. Both intense catastrophic fires and lower-intensity fires probably occurred naturally. Natural occurrences probably include both even-aged and uneven-aged canopies.

Outbreaks of southern pine beetle (Dendroctonus frontalis) are an important factor, at least under present conditions. Beetle outbreaks can kill the pines without creating the conditions for them to regenerate. Air pollutant stressors such as ozone and acid deposition are continuing to change the conditions that these stands respond to (O. Loucks pers. comm. 2013). If the pines are lost, the distinction between this vegetation and related oak-dominated forests and woodlands becomes blurred.
Environmental Description: Vegetation of this group encompasses predominantly evergreen woodlands and 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, as well as distinctive shale barrens of the Central and Southern Appalachians at low to mid elevations. They typically 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 group is best developed above 700 m (2300 feet) in elevation, but some examples may be found at lower elevations. 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.

In floristically distinctive shale barrens examples, the exposed aspects with very strong insolation, parent material with high levels of toxic metals, and lack of soil create extreme conditions for plant growth. The substrate includes areas of solid rock as well as unstable areas of shale scree, usually steeply sloped. The fully exposed areas are extremely dry. These barrens are high in endemic species.
Geographic Range: Vegetation of this group 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 the Northern Blue Ridge of south-central Pennsylvania and parts of Kentucky. The serpentine barrens portion is found from southern Pennsylvania south to Virginia and extreme eastern Tennessee. Application of the concept south of Virginia is uncertain.
Nations: US
States/Provinces: GA, KY, MD, NC, OH, PA, SC, TN, VA, WV
US Forest Service Ecoregions (2007)
Domain Name:
Division Name:
Province Name: Central Appalachian Broadleaf Forest - Coniferous Forest - Meadow Province
Province Code: M221    Occurrence Status: Confident or certain
Section Name: Northern Ridge and Valley Section
Section Code: M221A     Occurrence Status: Confident or certain
Omernik Ecoregions: 66:C, 66a:C, 66c:C, 66d:C, 66e:C, 66g:C, 66k:C, 66l:C, 66m:C, 67:C, 67c:C, 67d:C, 67h:C, 67i:C
Plot Analysis Summary:
Confidence Level: Moderate
Confidence Level Comments:
Grank: GNR
Greasons:
Concept Lineage:
Predecessors:
Obsolete Names:
Obsolete Parents:
Synonomy: > Pine Savanna/Woodland (Evans 1991)
< Pitch Pine - Virginia Pine Forest Group (Faber-Langendoen and Menard 2006) [Their group includes both this group and Pitch Pine Barrens Group (G161).]
Concept Author(s): N.L. Turrill and E.R. Buckner (1995)
Author of Description: M. Pyne
Acknowledgements:
Version Date: 04May2015
References:
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  • Faber-Langendoen, D., and S. Menard. 2006. A key to eastern forests of the United States: Macrogroups, groups, and alliances. September 15, 2006. NatureServe, Arlington, VA.
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  • Fleming, G. P., P. P. Coulling, K. D. Patterson, and K. M. McCoy. 2004. The natural communities of Virginia: Classification of ecological community groups. Second approximation. Natural Heritage Technical Report 04-01. Virginia Department of Conservation and Recreation, Division of Natural Heritage, Richmond, VA. [http://www.dcr.virginia.gov/dnh/ncintro.htm]
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