Classification of Vegetation Communities of Maryland: First Iteration

II. WOODLAND
II.B.2.N.a. Cold-deciduous woodland
II.B.2.N.a.28. TILIA AMERICANA - FRAXINUS AMERICANA - (ACER SACCHARUM)
WOODLAND ALLIANCE
American Basswood - White Ash - (Sugar Maple) Woodland Alliance

Concept: This alliance contains woodlands occurring on calcareous or circumneutral talus comprised of large boulders, or on rock outcrops. These woodlands often occur in association with rich forests, those of the Acer saccharum - Fraxinus americana - Tilia americana Forest Alliance (A.217). As opposed to the forest alliance, communities of woodland alliance have an open canopy and as such support more light-demanding species than are found in the understory of rich forests. Associated canopy species include Acer saccharum, Quercus rubra. The shrub layer is usually sparse. Herbs of this alliance include Adlumia fungosa, Clematis occidentalis, Geranium robertianum, Cystopteris bulbifera, Carex umbellata, and Antennaria plantaginifolia. This alliance occurs in southern Canada, lower New England, the northern Appalachians, and south to mountains of West Virginia and Virginia. In Maryland, this alliance is found along the Potomac River (Garrett County).

Range: This alliance occurs in southern Canada, lower New England, the northern Appalachians, and south to mountains of West Virginia and Virginia. In Maryland, this alliance is found along the Potomac River (Garrett County). It is found in Maine, Maryland, New Hampshire, New York, Vermont, Virginia, and West Virginia, and in Canada, and possibly in Massachusetts (?) and Pennsylvania (?).

States/Provinces: CT MA MD ME NB NH NY ON PA? VA VT WV

TNC Ecoregions: 48:C, 50:P, 59:C, 60:C, 61:C, 62:C, 63:C, 64:C

USFS Ecoregions: 212A:C?, 212B:C?, 212Dc:CCC, 212Ec:CCP, 212Ed:CCP, 212Ee:CCC, 212Fa:CCC, 212Fb:CCC, 212Fc:CCC, 212Ga:CCC, 221Af:CC?, 221Ah:CC?, 221Ai:CC?, 221Aj:CCC, 221Ak:CCP, 221Al:CCC, 221Ba:CCP, 221Bb:CCP, 221Bc:CCP, 221Bd:CCC, 222Ib:CCC, 222Ic:CCC, 222Ie:CCP, 222If:CCP, 251F:CP, 255A:CC, 311A:CC, 332E:CC, M212Ad:CCP, M212Ae:CCC, M212Af:CCC, M212Ag:CCC, M212Ba:CCC, M212Bb:CCP, M212Ca:CCC, M212Cc:CC?, M212Cd:CCC, M212Db:CCP, M212Dc:CCC, M212Df:CCC, M212Ea:CCC, M212Eb:CCC, M212Fb:CCC, M221Aa:CCC, M221Ba:CCP, M221Bb:CCP, M221Bd:CC?, M221Be:CC?, M221Ca:CC?, M221Cb:CC?, M221Cc:CC?, M221Cd:CCP, M221Da:CCC, M221Db:CCP

Federal Lands: NPS (Shenandoah); USFS (George Washington, Jefferson)

Synonymy: Circumneutral Talus Forest / Woodland (Swain and Kearsley 2001)

References: Sneddon et al. 1996, Swain and Kearsley 2001

Authors: ECS, RW, East Identifier: A.628  

Concept: This community type occurs throughout the northern Blue Ridge in Virginia and possibly the western Virginia Ridge and Valley region, as well as West Virginia and Maryland. Sites include steep, boulder and stone slides below cliffs; boulder-filled slope concavities and hollow-heads; and other very rocky, submesic to mesic habitats at middle elevations between 760 and 1030 m (2500-3400 feet). This is an open to closed, mixed hardwood forest, with tall, well-formed trees. Because of somewhat unstable substrates and occasional exposure to severe wind and ice storms, downfalls and crown damage may be frequent in some stands. Tilia americana (including both var. americana and var. heterophylla), Fraxinus americana, and Quercus rubra are the most abundant, variably dominant or codominant canopy trees. Carya cordiformis, Robinia pseudoacacia, and Carya ovata are minor but constant canopy associates. Understory layers tend to be open, with Acer pensylvanicum, Ostrya virginiana, Sambucus racemosa (= Sambucus pubens), and Ribes rotundifolium the most characteristic species. The usually patchy herb layer varies greatly in richness and density with substrate conditions.

Comments: Classification of this unit is supported by 15 plots from Alleghany, Amherst, Botetourt, Greene, Madison, Page, Rappahannock, Rockbridge, and Rockingham counties, Virginia (G. Fleming pers. comm.). Boulderfield forests and woodlands have not been thoroughly inventoried in Virginia and elsewhere. The global ranges and ecological relationships of this and other units are not well known and require additional study. In particular, the distribution and status of Tilia americana - Fraxinus americana / Acer pensylvanicum - Ostrya virginiana / Parthenocissus quinquefolia - Impatiens pallida Woodland (CEGL008528) in the Ridge and Valley province needs clarification. The distribution of this community type on the northern Blue Ridge appears to be centered above 760 m (2500 feet), where Liriodendron tulipifera begins to reach its upper elevational limits. Similar low-elevation habitats probably support Liriodendron tulipifera - Tilia americana - Betula lenta / Asimina triloba / Dryopteris marginalis Forest [Provisional] (CEGL008527). Above 1000-1060 m (3300-3500 feet; depending on aspect), this type is replaced by Betula alleghaniensis / Sorbus americana - Acer spicatum / Polypodium appalachianum Forest (CEGL008504).

Range: This community type definitely occurs in suitable habitats throughout the northern Blue Ridge in Virginia. Stands assigned to this type but somewhat transitional to northern hardwood forest, Betula alleghaniensis - Quercus rubra / Acer (pensylvanicum, spicatum) / Dryopteris intermedia - Oclemena acuminata Forest (CEGL008502), also occur on the northwest flank of Peters Mountain in Alleghany County. Similar forests have been observed in a few other sites of the western Virginia Ridge and Valley region. Occurrences of this community in West Virginia and Maryland are possible.

States/Provinces: MD?, VA:S?, WV?

TNC Ecoregions: 59:C

USFS Ecoregions: M221Aa:CCP, M221Da:CCC

Federal Lands: NPS (Shenandoah); USFS (George Washington, Jefferson)

Synonymy: Tilia americana - Fraxinus americana / Acer pensylvanicum - Ostrya virginiana / Parthenocissus quinquefolia - Impatiens pallida Woodland (Fleming and Coulling 2001) =, Tilia americana - Fraxinus americana / Ostrya virginiana / Ageratina altissima Forest (Fleming and Moorhead 2000), Liriodendron tulipifera - Acer saccharum - Tilia americana / Laportea candensis - Impatiens pallida Association, pro parte (Rawinski et al. 1996)

References: Fleming and Coulling 2001, Fleming and Moorhead 2000, Fleming et al. 2001, Rawinski et al. 1996

Authors: G. Fleming and P. Coulling, SCS Confidence: Identifier: CEGL008528

Concept: Open, talus slope woodlands in the mountainous sections of the High Allegheny and central Appalachian ecoregions. These are open woodlands of calcareous or bouldery circumneutral talus with a canopy of Acer saccharum, Fraxinus americana, Tilia americana, Quercus rubra. The shrub layer is scattered and viney and may include Acer spicatum, Acer pensylvanicum, Parthenocissus quinquefolia. Herbs include Adlumia fungosa, Clematis occidentalis, Geranium robertianum, Cystopteris bulbifera, Carex umbellata, Antennaria plantaginifolia.

States/Provinces: MD:S?, PA?, WV:S?

TNC Ecoregions: 59:C

USFS Ecoregions: M221Aa:CCC, M221B:CC

Synonymy: White ash-basswood-dogwood alkaline talus slope (CAP pers. comm. 1998)

References: CAP pers. comm. 1998

Authors: ECS Confidence: 3 Identifier: CEGL006054

- Maryland Vegetation Classification Subset Report II. Woodland

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