Invalid Unit Specified
M506 Rhododendron catawbiense / Saxifraga michauxii - Danthonia compressa Felsic & Mafic Scrub & Grassland Macrogroup

The U.S. National
Vegetation Classification
Type Concept Sentence: This vegetation macrogroup encompasses a variety of grass- and shrub-dominated communities, sometimes with scattered and/or stunted trees. This concept includes communities colloquially called balds, barrens, rock outcrops, and granitic flatrocks. Vegetation of this macrogroup is found in the Appalachian and Piedmont regions of the eastern United States with outliers in adjacent Canada.
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Common (Translated Scientific) Name: Catawba Rosebay / Michaux's Saxifrage - Flattened Oatgrass Felsic & Mafic Scrub & Grassland Macrogroup
Colloquial Name: Appalachian Rocky Felsic & Mafic Scrub & Grassland
Hierarchy Level: Macrogroup
Type Concept: This vegetation macrogroup encompasses a variety of grass- and shrub-dominated communities, sometimes with scattered and/or stunted trees, known colloquially as balds, barrens, flatrocks, rock outcrops, rocky domes, and rocky summits. They are found in the Appalachian and Piedmont regions of the eastern United States (with outliers in adjacent Canada), from higher to lower elevations. A suite of species tolerant of dry and rocky conditions are characteristic. At lower elevations this includes Danthonia spicata, Dichanthelium spp., and Schizachyrium scoparium, with trees including Pinus virginiana, Quercus montana, Quercus stellata, and/or Quercus velutina. At higher elevations this includes Carex pensylvanica, Danthonia compressa, Huperzia selago, Minuartia groenlandica, Sibbaldiopsis tridentata, and Trichophorum cespitosum. Shrubs may include Kalmia latifolia, Rhododendron catawbiense, and Vaccinium corymbosum. Appalachian oak barrens are dominated by grasses and shrubs, typically with scattered trees, including Juniperus virginiana var. virginiana, Quercus marilandica, Quercus montana, Quercus stellata, and/or Quercus velutina found on rocky substrates of a range of soil chemistries in the broadly-conceived Appalachian region. Appalachian balds may be dominated by shrubs or by graminoids and low forbs, and are found on higher peaks in the Southern Appalachians. The most characteristic species are Carex pensylvanica, Danthonia compressa, Rhododendron catawbiense, and Sibbaldiopsis tridentata. Granitic domes, flatrocks, and associated solution pools are found in the southern Piedmont of the United States. This vegetation is dominated by Croton michauxii var. ellipticus, Minuartia glabra, Packera tomentosa, Schizachyrium scoparium, and Phemeranthus spp., with Diamorpha smallii having high cover in some examples. The pools are distinctive and contain Amphianthus pusillus.
Diagnostic Characteristics: This macrogroup includes a variety of grass- and shrub-dominated communities, sometimes with scattered and/or stunted trees, found in the Appalachian and Piedmont regions of the eastern United States. This concept includes communities colloquially called balds, barrens, rock outcrops, and granitic flatrocks. It contains a diverse suite of physiognomies, including scattered trees over grasses and shrubs, to open grasslands, dense shrublands, and patchy herbaceous vegetation on rocky outcrops.
Rationale for Nominal Species or Physiognomic Features: It is hard to choose meaningful nominals for such a diverse unit. Possibilities for nominals include Carex pensylvanica, Danthonia spicata, Danthonia compressa, Rhododendron catawbiense, Saxifraga michauxii, and Schizachyrium scoparium, with possible trees including Pinus virginiana and Quercus montana. With only three nominals, it is hard to have one represent the Piedmont flatrock component.
Classification Comments: This is a diverse macrogroup. Choosing a set of nominals for the scientific name was a challenge. There is not a nominal to represent the Piedmont flatrock component. Although many of the species listed do occur in Massachusetts, there are enough southern species that don't get to Massachusetts, and for those related occurrences, Laurentian-Acadian Acidic Rocky Scrub & Grassland Macrogroup (M505) fits better.
Similar NVC Types:
M505 Laurentian-Acadian Acidic Rocky Scrub & Grassland, note: "is the related, but more northern and rocky type."
M508 Central Interior Calcareous Scrub & Grassland, note:
M509 Central Interior Acidic Scrub & Grassland, note:
Physiognomy and Structure: This macrogroup contains a diverse suite of physiognomies, including scattered trees over grasses and shrubs, to open grasslands, dense shrublands, and patchy herbaceous vegetation on rocky outcrops.
Floristics: A suite of species tolerant of dry and rocky conditions are generally characteristic of this vegetation. At lower elevations this includes Danthonia spicata, Dichanthelium spp., and Schizachyrium scoparium, with trees including Pinus virginiana, Quercus montana (= Quercus prinus), Quercus stellata, and/or Quercus velutina. At higher elevations this includes Carex pensylvanica, Danthonia compressa, Huperzia selago, Minuartia groenlandica, Sibbaldiopsis tridentata, and Trichophorum cespitosum. Shrubs may include Kalmia latifolia, Rhododendron catawbiense, and Vaccinium corymbosum. Appalachian oak barrens are dominated by grasses and shrubs, typically with scattered trees, including Juniperus virginiana var. virginiana, Quercus marilandica, Quercus montana, Quercus stellata, and/or Quercus velutina, found on rocky substrates of a range of soil chemistries in the broadly-conceived Appalachian region. Possible dominant graminoids include Andropogon virginicus, Carex pensylvanica, Danthonia spicata, Deschampsia flexuosa, Elymus hystrix (= Hystrix patula), Piptochaetium avenaceum, Schizachyrium scoparium, and Sporobolus compositus. Some other characteristic plants include Cheilanthes lanosa, Phacelia dubia, Phlox subulata, Polygonatum biflorum, Polygonum scandens var. cristatum, Tradescantia virginiana, and Woodsia obtusa. In more felsic examples, lichens (Cladonia spp.) and mosses are prominent on exposed rock. Appalachian balds may be dominated by shrubs or by graminoids and low forbs, and are found on higher peaks in the Southern Appalachians. The most characteristic species are Carex pensylvanica, Danthonia compressa, Rhododendron catawbiense, and Sibbaldiopsis tridentata. Granitic domes, flatrocks, and associated solution pools are found in the southern Piedmont of the United States. This vegetation is dominated by Croton michauxii var. ellipticus (= Croton willdenowii), Minuartia glabra, Packera tomentosa, Schizachyrium scoparium, and Phemeranthus (= Talinum) spp., with Diamorpha smallii having high cover in some examples. The pools are distinctive and contain Amphianthus pusillus.
Dynamics: No Data Available
Environmental Description: These grass- and shrub-dominated communities, sometimes with scattered and or stunted trees, are known colloquially as balds, barrens, flatrocks, rock outcrops, rocky domes, and rocky summits.
Geographic Range: This vegetation is found from the northeastern U.S. south through the Central and Southern Appalachians, Cumberland Plateau, and Piedmont south to Georgia and Alabama, and includes an outlier in southern Ontario, Canada.
Nations: US
States/Provinces: AL, GA, KY, MA, MD, NC, NJ, NY, PA, SC, TN, VA, WV
US Forest Service Ecoregions (2007)
Domain Name:
Division Name:
Province Name: Southeastern Mixed Forest Province
Province Code: 231    Occurrence Status: Confident or certain
Section Name: Southern Appalachian Piedmont Section
Section Code: 231A     Occurrence Status: Confident or certain
Omernik Ecoregions: 45:C, 45b:C, 45f:C, 64:C, 66:C, 66i:C, 67:P
Plot Analysis Summary:
Confidence Level: Moderate
Confidence Level Comments:
Grank: GNR
Greasons:
Name:Database Code:Classification Code:
Class 2 Shrub & Herb Vegetation C02 2
Subclass 2.B Temperate & Boreal Grassland & Shrubland S18 2.B
Formation 2.B.2 Temperate Grassland & Shrubland F012 2.B.2
Division 2.B.2.Nc Eastern North American Grassland & Shrubland D024 2.B.2.Nc
Macrogroup M506 Appalachian Rocky Felsic & Mafic Scrub & Grassland M506 2.B.2.Nc.1
Group G180 Appalachian Mafic Glade G180 2.B.2.Nc.1.c
Group G657 Southern Appalachian Grass Bald G657 2.B.2.Nc.1.b
Group G658 Southern Appalachian Shrub Bald G658 2.B.2.Nc.1.a
Group G670 Southern Appalachian Rocky Outcrop G670 2.B.2.Nc.1.d
Group G671 Piedmont Dome & Flatrock Vegetation G671 2.B.2.Nc.1.f
Concept Lineage:
Predecessors:
Obsolete Names:
Obsolete Parents:
Synonomy:
Concept Author(s): M. Pyne, in Faber-Langendoen et al. (2014)
Author of Description: M. Pyne
Acknowledgements:
Version Date: 06Jan2016
References:
  • Faber-Langendoen, D., J. Drake, S. Gawler, M. Hall, C. Josse, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, L. Sneddon, K. Schulz, J. Teague, M. Russo, K. Snow, and P. Comer, editors. 2010-2019a. Divisions, Macrogroups and Groups for the Revised U.S. National Vegetation Classification. NatureServe, Arlington, VA. plus appendices. [in preparation]