Print Report

CEGL004242 Danthonia compressa - (Sibbaldiopsis tridentata) Grassland

Type Concept Sentence: No Data Available

Common (Translated Scientific) Name: Flattened Oatgrass - (Shrubby Fivefingers) Grassland

Colloquial Name: Grassy Bald (Southern Grass Type)

Hierarchy Level:  Association

Type Concept: This community consists of graminoid-dominated vegetation with scattered shrubs, occurring on moderate to high-elevation peaks and saddles in the Southern Blue Ridge. Characteristically, this vegetation is strongly dominated by Danthonia compressa, or in some areas codominated by the subshrub Sibbaldiopsis tridentata. Other characteristic herbaceous species are Angelica triquinata, Carex pensylvanica, Carex debilis, Carex intumescens, Carex brunnescens, Deschampsia flexuosa, Erythronium umbilicatum ssp. monostolum, Gentiana austromontana, Gentianella quinquefolia, Houstonia serpyllifolia, Ionactis linariifolius, Lysimachia quadrifolia, Oclemena acuminata, Potentilla canadensis, Prenanthes roanensis, Smilax herbacea, Solidago bicolor, Solidago glomerata, Stachys clingmanii, and Trautvetteria caroliniensis var. caroliniensis. The floristic composition is a mixture of widespread species, northern disjunct species, such as Agrostis mertensii, Carex siccata, Minuartia groenlandica, Packera schweinitziana, and Sibbaldiopsis tridentata, and Southern Appalachian endemics, such as Erythronium umbilicatum ssp. monostolum, Geum geniculatum, Geum radiatum, Houstonia serpyllifolia, Lilium grayi, Prenanthes roanensis, Solidago glomerata, and Stachys clingmanii). Typical shrubs (which may occur as scattered individuals or as patches) are Rhododendron calendulaceum, Rhododendron catawbiense, Menziesia pilosa, Vaccinium corymbosum, and Rubus canadensis. Species indicative of past grazing include Phleum pratense, Agrostis gigantea, Hieracium scabrum, Rumex acetosella, and Prunella vulgaris. This community occurs on high-elevation (usually above 1350 m [4500 feet]), often south- to southwest-facing domes, ridgetops, and gentle slopes. Strong winds, high rainfall, frequent fog, shallow rocky soils, and extremes of temperature and moisture are characteristic of these environments. It is known from the highest elevations of the southern Appalachian Mountains. It is typically surrounded by dwarfed forests dominated by Fagus grandifolia or Quercus rubra.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Notable examples include various peaks of the Roan Mountain complex, Long Hope Valley, Shining Rock Wilderness, and Great Smoky Mountains National Park. The origin of this community is not clear, and in fact, several mechanisms, both natural and anthropogenic, have been proposed including fire, grazing, trampling, clearing, climatic change, windthrow, or some combination of these influences. The presence of northern disjunct species requiring open habitat may suggest that some of these areas have been open since the Ice Age. A. Weakley (pers. comm.) suggests that the balds of Roan Mountain, Tennessee, are primarily natural, whereas those farther north are of anthropogenic origin. It appears that new occurrences of this community are not being created, and those that exist are being encroached by shrub and tree species. Lindsay (1976) reported that examples of this community in Great Smoky Mountains National Park will have disappeared by the end of the century if management is not undertaken to halt invasion by woody plants. However, these balds are among those most likely to be of anthropogenic origin. Six plots from Roan Mountain, Whitetop Mountain, and Gregory Bald were classified as this association in the Appalachian Trail project (Fleming and Patterson 2009a). Several plots have high cover by shrubs (Amelanchier laevis, Rhododendron catawbiense, Rubus canadensis, Vaccinium corymbosum, Vaccinium erythrocarpum, Vaccinium pallidum) indicating woody encroachment or plot placement in an ecotone. Species that have >67% constancy are, in order of descending constancy, Danthonia compressa, Sibbaldiopsis tridentata, Dennstaedtia punctilobula, Carex debilis var. rudgei, Rubus canadensis, Rumex acetosella, and Saxifraga michauxii.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available

Floristics: This vegetation is graminoid-dominated with scattered shrubs. Most occurrences are strongly dominated by Danthonia compressa, but some sites are codominated by the subshrub Sibbaldiopsis tridentata (= Potentilla tridentata). Other characteristic herbaceous species are Angelica triquinata, Carex pensylvanica, Carex debilis var. rudgei, Carex intumescens, Carex brunnescens ssp. sphaerostachya, Deschampsia flexuosa, Erythronium umbilicatum ssp. monostolum, Gentiana austromontana, Gentianella quinquefolia, Houstonia serpyllifolia, Ionactis linariifolius (= Aster linariifolius), Lysimachia quadrifolia, Oclemena acuminata (= Aster acuminatus), Potentilla canadensis, Prenanthes roanensis, Smilax herbacea, Solidago bicolor, Solidago glomerata, Stachys clingmanii, and Trautvetteria caroliniensis var. caroliniensis. The floristic composition is a mixture of widespread species, northern disjunct species such as Sibbaldiopsis tridentata; and Southern Appalachian endemics such as Houstonia serpyllifolia, Lilium grayi, and Prenanthes roanensis. Typical shrubs, which may occur as scattered individuals or patches are Rhododendron calendulaceum, Rhododendron catawbiense, Menziesia pilosa, Vaccinium corymbosum, and Rubus canadensis. Invasive, introduced species indicative of past grazing include Phleum pratense, Agrostis gigantea, Hieracium caespitosum, Poa compressa, Rumex acetosella, and Prunella vulgaris.

In the least disturbed, most natural areas, the most abundant or characteristic herbaceous associates are Carex brunnescens ssp. sphaerostachya, Carex debilis var. rudgei, Lysimachia quadrifolia, Dennstaedtia punctilobula, Carex pensylvanica, Potentilla canadensis, Prenanthes roanensis, Solidago rugosa, Ageratina altissima var. roanensis, and Hypericum mitchellianum. Despite the exposed topography, atmospheric conditions create a very moist microclimate, as evidenced by large populations of species often associated with wetlands, including Helenium autumnale, Packera aurea, Houstonia serpyllifolia, Solidago patula, and Carex intumescens.

Rare or northern disjunct plant species reported from this community include Agrostis mertensii, Alnus viridis ssp. crispa, Botrychium multifidum, Calamagrostis canadensis, Carex siccata (= Carex aenea), Carex cristatella, Carex misera, Delphinium exaltatum, Gentiana austromontana, Geum geniculatum, Houstonia purpurea var. montana, Huperzia selago, Hypericum buckleii, Lilium grayi, Lilium philadelphicum, Lycopodium dendroideum, Lycopodium hickeyi, Minuartia groenlandica, Monarda media, Phlox subulata, Platanthera grandiflora, Poa palustris, Prenanthes roanensis, Rhododendron cumberlandense, Rhododendron vaseyi, Packera schweinitziana (= Senecio schweinitzianus), Spiranthes ochroleuca, and Trisetum spicatum (Schafale and Weakley 1990). Exotic species that occur, probably as a result of grazing, include Prunella vulgaris, Phleum pratense, and Poa compressa.

Dynamics:  The origin and ecological dynamics of this vegetation type are not clear. Several disturbance mechanisms, both natural and anthropogenic, have been hypothesized, including fire, grazing, trampling, clearing, climatic change, windthrow, or some combination of these influences. The importance of megaherbivores in long-term bald maintenance has recently been proposed (Wiegl and Knowles 1999). It appears that new occurrences of this community are not being created, and that many existing ones are being encroached by shrub and tree species. The presence of northern disjunct species requiring open habitat suggests that some of these areas have been open since the Pleistocene. This is the case at Whitetop Mountain, Virginia, although there is little question that the original openings were greatly expanded during a long history of grazing and the development of a 19th century resort. A. Weakley (pers. comm. 2001) suggests that the balds of Roan Mountain, Tennessee, are primarily natural, whereas those farther north are of anthropogenic origin.
Environmental Description:  This community occurs on high-elevation (usually above 1350 m [4500 feet]), often south- to southwest-facing domes, ridgetops, and gentle slopes. Strong winds, high rainfall, frequent fog, shallow rocky soils, and extremes of temperature and moisture are characteristic of these environments. In North Carolina and Tennessee, this grassland vegetation is typically surrounded by dwarfed forests dominated by Fagus grandifolia or Quercus rubra. On Whitetop Mountain, Virginia, the type occurs at elevations from 1525-1655 m (5000-5430 feet), adjacent to both well-developed Picea rubens-dominated forests and stunted northern hardwoods. Soils are extremely acidic (pH = 3.8), with low (5%) base saturation, high aluminum levels (1600 ppm), and relatively high (27%) organic matter content.
Geographic Range: This montane sparse dwarf-shrubland is found in the high mountain areas of the Southern Appalachians. While the majority of examples occur in North Carolina, this community is also known from Tennessee and Virginia.

Nations: US

States/Provinces:  NC, TN, VA


Confidence Level: Moderate

Confidence Level Comments: No Data Available
Grank: G1

Greasons: No Data Available
Type Name Database Code Classification Code
Class 2 Shrub & Herb Vegetation Class C02 2
Subclass 2.B Temperate & Boreal Grassland & Shrubland Subclass S18 2.B
Formation 2.B.2 Temperate Grassland & Shrubland Formation F012 2.B.2
Division 2.B.2.Nc Eastern North American Grassland & Shrubland Division D024 2.B.2.Nc
Macrogroup 2.B.2.Nc.1 Catawba Rosebay / Michaux''s Saxifrage - Flattened Oatgrass Felsic & Mafic Scrub & Grassland Macrogroup M506 2.B.2.Nc.1
Group 2.B.2.Nc.1.b Pennsylvania Sedge - Flattened Oatgrass - Shrubby Fivefingers Southern Appalachian Grass Bald Group G657 2.B.2.Nc.1.b
Alliance A2026 Pennsylvania Sedge - Flattened Oatgrass - Blue Ridge St. John''s-wort Grass Bald Alliance A2026 2.B.2.Nc.1.b
Association CEGL004242 Flattened Oatgrass - (Shrubby Fivefingers) Grassland CEGL004242 2.B.2.Nc.1.b
Concept Lineage: Merged into

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Danthonia compressa - Carex brunnescens ssp. sphaerostachya - Sibbaldiopsis tridentata Herbaceous Vegetation (Fleming and Coulling 2001)
< ID9a. Grass Bald (Allard 1990)
Concept Author(s): K.D. Patterson

Author of Description: K.D. Patterson

Acknowledgements: No Data Available

Version Date: 06-21-01
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