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CEGL006124 Betula alleghaniensis / Ribes glandulosum / Polypodium appalachianum Forest
Type Concept Sentence: No Data Available
Common (Translated Scientific) Name: Yellow Birch / Skunk Currant / Appalachian Polypody Forest
Colloquial Name: Southern Appalachian Boulderfield Forest (Currant & Rockcap Fern Type)
Hierarchy Level: Association
Type Concept: This association includes high-elevation boulderfield forests of the Southern Appalachians, strongly dominated by Betula alleghaniensis, with few or no other species in the canopy, and with other species indicative of high elevations. This community occurs in a cool, humid climate, on steep, rocky, northwest- to northeast-facing, middle to upper concave slopes, or in saddles between ridges, at elevations of 1370-1615 m (4500-5300 feet). It is known from the high elevations of the Blue Ridge from West Virginia south to eastern Tennessee and western North Carolina. This forest is distinguished by a closed to somewhat open canopy dominated by Betula alleghaniensis, occurring over angular rocks (0.25-1 m diameter) covered by thin soil, lichens, mosses or vines. The rocks may be almost totally covered by moss. Betula alleghaniensis in the canopy are often stunted and gnarled, with roots that may have grown to encircle the boulders. Tree density is typically less than that of the surrounding forests. Other species that may form a minor canopy component include Aesculus flava, Prunus pensylvanica, Sorbus americana, Acer spicatum, Picea rubens, Tilia americana var. heterophylla, Sambucus racemosa var. racemosa, or Quercus rubra. Tree windthrow is common, leaving patches of exposed mineral soil and gaps in the canopy. The shrub density is typically high but may vary between occurrences. Herbaceous cover is generally sparse because of thin, rocky soil, but herbs and mosses may cover the rocks and boulders. Characteristic species include, in the herb stratum, Oclemena acuminata, Eurybia chlorolepis, Aconitum reclinatum, Cardamine clematitis, Carex aestivalis, Actaea podocarpa, Claytonia caroliniana, Clintonia borealis, Dryopteris campyloptera, Dryopteris marginalis, Huperzia lucidula, Oxalis montana, Polypodium appalachianum, Streptopus amplexifolius, and in the shrub stratum, Acer pensylvanicum, Acer spicatum, Amelanchier arborea var. austromontana, Diervilla sessilifolia, Hydrangea arborescens, Ilex montana, Lonicera canadensis, Ribes glandulosum, Ribes rotundifolium, Rubus canadensis, Sambucus racemosa var. racemosa, Vaccinium erythrocarpum, and Viburnum lantanoides. Seepage areas are common, producing wet microhabitats with unique species assemblages (Chelone lyonii, Chrysosplenium americanum, Circaea alpina, Rudbeckia laciniata, Impatiens pallida, and Monarda didyma). This association is distinguished by being strongly dominated by Betula alleghaniensis, with few or no other species in the canopy, and with other species indicative of high elevations (e.g., Abies fraseri, Dryopteris campyloptera, Ribes glandulosum, Rugelia nudicaulis, Streptopus amplexifolius, Prunus pensylvanica, and Sorbus americana. On less extreme sites, generally at lower elevations in the Blue Ridge and adjacent montane ecoregions, a similar boulderfield forest is ~Betula alleghaniensis - Tilia americana var. heterophylla / Acer spicatum / Ribes cynosbati / Dryopteris marginalis Forest (CEGL004982)$$. Similar Betula alleghaniensis-dominated forests occur on glaciated rocky slopes in the upper mid-Atlantic and in the northeastern United States. The Betula alleghaniensis-dominated periglacial boulderfields of the southern Appalachian Mountains are distinguished from the northern forests by the occurrence of Southern Appalachian endemic species, better developed shrub layers and slightly less species diversity.
Diagnostic Characteristics: No Data Available
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: Unlike many other forest types in the Southern Appalachians, this community has not been threatened by logging because of the stunted nature of the trees and the inaccessibility of boulderfields to loggers.
This association is similar to ~Betula alleghaniensis / Sorbus americana - Acer spicatum / Polypodium appalachianum Forest (CEGL008504)$$ of the Central Appalachians, but appears to occupy more mesic boulderfields and contains a number of Southern Appalachian species (e.g., Ribes glandulosum, Eurybia chlorolepis, Heuchera villosa, Abies fraseri, Prenanthes roanensis, Vaccinium erythrocarpum, Aesculus flava, etc.) that are generally absent from CEGL008504.
This association is similar to ~Betula alleghaniensis / Sorbus americana - Acer spicatum / Polypodium appalachianum Forest (CEGL008504)$$ of the Central Appalachians, but appears to occupy more mesic boulderfields and contains a number of Southern Appalachian species (e.g., Ribes glandulosum, Eurybia chlorolepis, Heuchera villosa, Abies fraseri, Prenanthes roanensis, Vaccinium erythrocarpum, Aesculus flava, etc.) that are generally absent from CEGL008504.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available
Floristics: Stands of this association are distinguished by a closed to somewhat open canopy overwhelmingly dominated by Betula alleghaniensis. Canopy trees are often stunted and gnarled, with roots that have grown to encircle the boulders. Tree density is typically less than that of the surrounding forests. Minor canopy associates include Aesculus flava, Prunus pensylvanica, Sorbus americana, Acer spicatum, Picea rubens, Tilia americana var. heterophylla, and Quercus rubra. Tree windthrow is common, creating canopy gaps and patches of exposed mineral soil. Shrub density is typically high but varies between occurrences. Characteristic shrubs are Acer pensylvanicum, Acer spicatum, Amelanchier arborea var. austromontana, Diervilla sessilifolia, Hydrangea arborescens, Ilex montana, Lonicera canadensis, Ribes glandulosum, Ribes rotundifolium, Rubus canadensis, Sambucus racemosa var. racemosa (= var. pubens), Vaccinium erythrocarpum, and Viburnum lantanoides. Herbaceous cover is generally sparse because of the rocky substrate, but specially adapted herbs and mosses may cover the rocks and boulders. Characteristic herbs over the range of this community include Oclemena acuminata (= Aster acuminatus), Eurybia chlorolepis (= Aster chlorolepis), Aconitum reclinatum, Cardamine clematitis, Carex aestivalis, Actaea podocarpa (= Cimicifuga americana), Claytonia caroliniana, Clintonia borealis, Dryopteris campyloptera, Dryopteris marginalis, Huperzia lucidula, Oxalis montana, Polypodium appalachianum, and Streptopus amplexifolius. Local seepage areas may support Chelone lyonii, Chrysosplenium americanum, Circaea alpina, Rudbeckia laciniata, Impatiens pallida, and Monarda didyma. Six plots from North Carolina, Tennessee, and Virginia were classified as this association in the Appalachian Trail classification project (Fleming and Patterson 2009a). In those plots, Acer spicatum, Ribes glandulosum, Rubus canadensis, and Viburnum lantanoides are the most constant lower woody species, while Ageratina altissima var. roanensis, Arisaema triphyllum, Carex aestivalis, Dryopteris intermedia, Eurybia chlorolepis, Huperzia lucidula, Oclemena acuminata, and Polypodium appalachianum are the most constant herbs. Mean species richness in these samples is 28 taxa per plot.
Dynamics: Windthrow of trees and damage to the canopy caused by lightning strikes and ice storms are common phenomena in boulderfields. The ice-fractured boulderfields that characterize this community in the upper elevations of the Southern Appalachians are believed to be remnants of Pleistocene periglacial activity. During this time, the high elevations (1120-1525 m [4000-5000 feet]) of the Southern Appalachians were covered by treeless snow fields and exposed rock. Frost and ice action resulted in the accumulation of boulders that persist on the upper slopes (King and Stupka 1950). Farther north, such as in Pennsylvania, boulderfields are on flat surfaces and are the result of glacial deposition (Allard 1984).
Betula alleghaniensis is well-adapted to the environmental dynamics of boulderfields and can perpetuate because it takes advantage of canopy gaps formed during periodic natural disturbances. This species produces a large number of seeds and is able to germinate on logs and rocks in a minimum amount of soil. The roots of trees develop to form false trunks that encircle the rocks. It is possible that over time, due to soil formation and weathering, these forests may succeed to forests dominated by a mixture of northern hardwood species (Betula alleghaniensis, Fagus grandifolia, Acer saccharum, Aesculus flava). However, many Betula alleghaniensis forests and the boulderfields on which they occur appear fairly stable. Chafin and Jones (1989) found that despite large trees growing on top of boulders, there is no evidence of rock shattering.
Betula alleghaniensis is well-adapted to the environmental dynamics of boulderfields and can perpetuate because it takes advantage of canopy gaps formed during periodic natural disturbances. This species produces a large number of seeds and is able to germinate on logs and rocks in a minimum amount of soil. The roots of trees develop to form false trunks that encircle the rocks. It is possible that over time, due to soil formation and weathering, these forests may succeed to forests dominated by a mixture of northern hardwood species (Betula alleghaniensis, Fagus grandifolia, Acer saccharum, Aesculus flava). However, many Betula alleghaniensis forests and the boulderfields on which they occur appear fairly stable. Chafin and Jones (1989) found that despite large trees growing on top of boulders, there is no evidence of rock shattering.
Environmental Description: This community occurs in rocky habitats with cool, humid microclimates. Typical sites are steep, boulder-strewn slopes; northwest- to northeast-facing, middle to upper concave slopes; or in saddles between ridges. Elevations typically range from 1370-1615 m (4500-5300 feet), but may vary somewhat. Surface substrate is characterized by angular boulders (0.25-1 m diameter) derived from various bedrock types and covered by thin soil, lichens, mosses or vines. The rocks may be almost totally covered by moss. Seepage areas are frequent, producing wet microhabitats with unique species assemblages. Extreme winter temperatures, high winds, and ice storms periodically affect these forests. Mean elevation of plot-sampled Virginia sites is 1450 m (4760 feet) and aspect ranges from northwest to north. Mean surface cover of exposed bedrock and boulders is 42% and mean cover of bryophytes and lichens is 37%. Soil samples collected from these sites are extremely acidic (mean pH = 3.5), with high organic matter content (mean = 40%) and low base saturation (mean = 10%).
Geographic Range: This community type ranges at high elevations of the Blue Ridge from eastern Tennessee and western North Carolina north to southwestern Virginia. In the southern Virginia Blue Ridge, it occurs frequently on steep, north-facing slopes of Mount Rogers, Whitetop, and Pine Mountain. Small, highly localized outliers also occur at the highest elevations of Clinch Mountain in the adjacent Ridge and Valley province.
Nations: US
States/Provinces: GA?, NC, TN, VA, WV?
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.685747
Confidence Level: Moderate
Confidence Level Comments: No Data Available
Grank: G2G3
Greasons: No Data Available
| Type | Name | Database Code | Classification Code |
|---|---|---|---|
| Class | 1 Forest & Woodland Class | C01 | 1 |
| Subclass | 1.B Temperate & Boreal Forest & Woodland Subclass | S15 | 1.B |
| Formation | 1.B.2 Cool Temperate Forest & Woodland Formation | F008 | 1.B.2 |
| Division | 1.B.2.Na Eastern North American Forest & Woodland Division | D008 | 1.B.2.Na |
| Macrogroup | 1.B.2.Na.3 Appalachian-Interior-Northeastern Mesic Forest Macrogroup | M883 | 1.B.2.Na.3 |
| Group | 1.B.2.Na.3.b Appalachian-Allegheny Northern Hardwood Forest | G742 | 1.B.2.Na.3.b |
| Alliance | A0266 Yellow Birch - Yellow Buckeye Forest Alliance | A0266 | 1.B.2.Na.3.b |
| Association | CEGL006124 Yellow Birch / Skunk Currant / Appalachian Polypody Forest | CEGL006124 | 1.B.2.Na.3.b |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Betula alleghaniensis / Acer spicatum / Viburnum lantanoides - Ribes glandulosum Forest (Fleming and Coulling 2001)
< Hemlock - Yellow Birch: 24 (Eyre 1980)
< IA4c. Yellow Birch Boulderfield Forest (Allard 1990)
< Oligotrophic Forest (Rawinski 1992)
< Red Spruce - Yellow Birch: 30 (Eyre 1980)
< Sugar Maple - Beech - Yellow Birch: 25 (Eyre 1980)
? Yellow Birch Community: Boulder Field Subtype (Rheinhardt and Ware 1984)
? Yellow birch-skunk current/polypody forest (CAP pers. comm. 1998)
< Hemlock - Yellow Birch: 24 (Eyre 1980)
< IA4c. Yellow Birch Boulderfield Forest (Allard 1990)
< Oligotrophic Forest (Rawinski 1992)
< Red Spruce - Yellow Birch: 30 (Eyre 1980)
< Sugar Maple - Beech - Yellow Birch: 25 (Eyre 1980)
? Yellow Birch Community: Boulder Field Subtype (Rheinhardt and Ware 1984)
? Yellow birch-skunk current/polypody forest (CAP pers. comm. 1998)
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- CAP [Central Appalachian Forest Working Group]. 1998. Central Appalachian Working group discussions. The Nature Conservancy, Boston, MA.
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