Classification of Vegetation Communities of Maryland: First Iteration

I. FOREST
I.B.2.N.a. Lowland or submontane cold-deciduous forest
I.B.2.N.a.46. CARYA (GLABRA, OVATA) - FRAXINUS AMERICANA - QUERCUS (ALBA, RUBRA) FOREST ALLIANCE
(Pignut Hickory, Shagbark Hickory) - White Ash - (White Oak, Northern Red Oak) Forest Alliance

Concept: Communities of this alliance include dry, relatively 'rich' forests dominated by Quercus species and include Carya species as a prominent (rarely codominant) feature. Fraxinus americana, although sometimes a sporadic member, is generally characteristic of these forests. Associated canopy species include Quercus alba, Quercus velutina, Quercus rubra, Carya ovalis, Carya glabra, as well as other oaks and hickories. Communities of this alliance generally occur on dry upper slopes or ridgetops. Soils are usually rich, and may range from slightly acidic to circumneutral pH, on well-drained loams or sandy loams, predominantly on southern or eastern exposures. The shrub layer is usually interrupted to absent. When present, it includes Viburnum rafinesquianum, and occasional Vaccinium species. Viburnum acerifolium is characteristic of some communities of this alliance. Although ericaceous species may be present and occasionally locally abundant, they are not characteristic. The herbaceous layer is characterized by forbs and may be quite diverse. A characteristic sedge is Carex pensylvanica. Other forbs found in these communities include Asplenium platyneuron, Schizachyrium scoparium, Hepatica nobilis var. obtusa (= Hepatica americana), Asclepias quadrifolia, Desmodium spp., and Arabis canadensis. The relatively open canopy, sparse shrub layer, and dense herbaceous layer impart a park-like appearance to many of these forests. However, this vegetation is classified as forest rather than woodland because total canopy cover generally exceeds 60%, and few, if any, of the herbs may be thought of as truly shade-intolerant. Those herbs that require high light levels are generally confined to small openings. Portions of SAF type 52, White Oak - Black Oak - Northern Red Oak, are contained within this alliance. These forests are somewhat similar to Braun's (1950) 'oak-hickory forests' of the Midwest. They share many of the same canopy species, and in some cases, similar physiognomy. However, the Oak-Hickory Region of Braun supports forests that occur in close association and intergrade with prairies, and share many of the same species in the herb layer, particularly legumes. For example, Asclepias verticillata, Lithospermum canescens, Tephrosia virginiana, Desmodium spp., Euphorbia corollata, and Liatris spp. occur in many of the oak - hickory forests of the Ozark Plateau, and Braun (1950) suggests that they may be remnants of prairie openings invaded by forest. A few outliers of 'Oak - Hickory' forests do occur in the East, however, and these are placed within the Quercus velutina - Quercus alba - (Quercus coccinea) Forest Alliance (A.1911).

Comments: Portions of SAF type 52, White Oak - Black Oak - Northern Red Oak, are contained within this alliance. These forests are somewhat similar to Braun's (1950) 'oak-hickory forests' of the Midwest. They share many of the same canopy species and, in some cases, similar physiognomy. However, the Oak-Hickory Region of Braun supports forests that occur in close association and intergrade with prairies, and share many of the same species in the herb layer, particularly legumes. For example, Asclepias verticillata, Lithospermum canescens, Tephrosia virginiana, Desmodium spp., Euphorbia corollata, and Liatris spp. occur in many of the oak - hickory forests of the Ozark Plateau, and Braun (1950) suggests that they may be remnants of prairie openings invaded by forest.

Range: This alliance is found in New York, Pennsylvania (?), Maryland (?), New Jersey (?), Delaware (?), Vermont, Connecticut, Massachusetts, and New Hampshire.

States/Provinces: CT DE? MA MD ME NH NJ NY PA RI VA VT WV

TNC Ecoregions: 49:C, 50:?, 52:C, 59:C, 60:C, 61:C, 62:C, 63:C, 64:C

USFS Ecoregions: 212Da:CPP, 212Ea:CC?, 212Eb:CC?, 212Ec:CCP, 212Ed:CCP, 212Fa:CCC, 212Fb:CCC, 212Fc:CCC, 212Fd:CCC, 212Ga:CCC, 212Gb:CCC, 221Aa:CC?, 221Ab:CCC, 221Ae:CCC, 221Af:CCC, 221Ag:CCC, 221Ah:CCC, 221Ai:CCC, 221Aj:CCP, 221Ak:CCC, 221Al:CCP, 221Am:CCP, 221Ba:CCC, 221Bb:CCC, 221Bc:CCC, 221Bd:CCC, 221Da:CCP, 221Dc:CCC, 221Ea:CCC, 221Eb:CCP, 221Fa:CCC, 222Ia:CCP, 222Ib:CCP, 222Ic:CCP, 222Id:CCP, 222Ie:CCP, 222If:CCP, 222O:C?, 231Ae:CCP, 231Ak:CCC, 231Al:CCC, 231Am:CCP, 231Ap:CCC, M212Bb:CCC, M212Bd:CCC, M212Cb:CCC, M212Cc:CCC, M212Cd:CCP, M212Db:CCP, M212Dc:CCC, M212De:CCC, M212Ea:CCC, M212Eb:CCC, M221Aa:CPP, M221Ab:CPP, M221Ba:CP?, M221Bb:CPP, M221Bc:CP?, M221Bd:CPP, M221Be:CPP, M221Bf:CPP, M221Ca:CPP, M221Cb:CPP, M221Da:CCC, M221Dc:CCC

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

Synonymy: White Oak - Black Oak - Northern Red Oak: 52, in part (Eyre 1980); "oak-hickory forests" (Braun 1950); Hickory - Hop Hornbeam Forest / Woodland (Swain and Kearsley 2001); Dry, Rich Acidic Oak Forest (Swain and Kearsley 2001); Dry oak - mixed hardwood forest (Fike 1999); Dry-Mesic Calcareous Central Forest (Smith 1991); Xeric Central Hardwood Forest (Smith 1991)

References: Braun 1950, Eyre 1980, Fike 1999, Smith 1991, Swain and Kearsley 2001

Authors: ECS, East Identifier: A.258

Concept: This dry, rich, closed-canopy oak - hickory forest occurs in the Lower New England - Northern Piedmont, Central Appalachians, Western Allegheny Plateau, and High Allegheny Plateau ecoregions. This association is found on dry, southern or southeastern, mid to upper slopes on slightly acidic to circumneutral, well-drained loams or sandy loams. The tree canopy is dominated by Quercus species with Carya species (typically over 20% cover Carya) and Fraxinus americana as prominent (rarely codominant) features. Associates include Quercus alba, Quercus velutina, Quercus rubra, Quercus prinus, Carya ovalis, Carya glabra, Carya cordiformis, and Cornus florida. Acer saccharum, Acer rubrum, Celtis occidentalis, Tilia americana, and Betula lenta may be present also. The interrupted shrub layer contains Carpinus caroliniana, Corylus spp., Viburnum rafinesquianum, Vaccinium spp., and Viburnum acerifolium. Ericaceous species are present but not prominent. The diverse herbaceous layer includes Carex pensylvanica, Asplenium platyneuron, Schizachyrium scoparium, Hepatica nobilis var. obtusa (= Hepatica americana), Asclepias quadrifolia, Desmodium spp., and Arabis canadensis.

Range: This forest occurs in the Lower New England - Northern Piedmont, Central Appalachians, Western Allegheny Plateau, and High Allegheny Plateau ecoregions.

States/Provinces: CT:S?, DE?, MA:S4, MD:S?, NH:S?, NJ?, NY:S4, PA:S?, VT:S3, WV:S?

TNC Ecoregions: 49:C, 59:C, 60:C, 61:C

USFS Ecoregions: 212Fa:CCC, 212Fb:CCC, 212Fc:CCC, 212Fd:CCC, 212Ga:CCC, 212Gb:CCC, 221Ae:CCP, 221Af:CCC, 221Ai:CCC, 221Bd:CCC, 221D:C?, 221Ea:CCC, 221Fa:CCC, 231A:??, M212Bb:CCC, M212Bd:CCC, M212Cb:CCC, M212Cc:CCC, M212Ea:CCC, M212Eb:CCC, M221A:CP, M221B:CP, M221C:CP, M221Dc:CCC

Federal Lands: NPS (Harpers Ferry)

Synonymy: SNE dry rich forest on acidic/circumneutral bedrock or till (Rawinski 1984), Mesic Transition Hardwood Forest (Mesic Oak-Hickory-Northern Hardwood Forest) (Thompson 1996)

References: Breden et al. 2001, CAP pers. comm. 1998, Edinger et al. 2002, Fike 1999, Lundgren 2000, Lundgren 2001, Metzler and Barrett 2001, Rawinski 1984, Swain and Kearsley 2001, Thompson 1996, Thompson and Sorensen 2000, Vanderhorst 2000b

Authors: ECS Confidence: 3 Identifier: CEGL006236

Concept: This community type is currently known from scattered locations on the northern Virginia Blue Ridge. Occurrences on the Maryland Blue Ridge and in the Ridge and Valley of Virginia, West Virginia, and Maryland are possible. Sites are lower to middle-elevation mountain slopes underlain by Catoctin Formation metabasalt (greenstone), layered pyroxene granulite, and metasiltstone and phyllite of the Harper's Formation. Elevation ranges from 390-995 m (1280-3260 feet). Although middle-slope positions are most typical, topographic positions from lower slopes to crests are represented, and the moisture potential of these sites was assessed as submesic or subxeric. Slopes are typically steep, with aspects ranging from northeast to southwest. This association has an open, mixed canopy dominated by several oaks and hickories. Trees tend to be slightly stunted (often <20 m tall) on the drier and more exposed sites. Quercus prinus and Carya ovalis are the most abundant canopy species, but Quercus rubra and Fraxinus americana are constant, sometimes codominant associates. Carya ovata and Carya glabra each attain codominance in a subset of stands. Few other trees co-occur, and understory layers tend to be open or sparse with scattered Ostrya virginiana, Crataegus flabellata, and tree saplings. Vaccinium stamineum, Vaccinium pallidum, Rosa carolina, and Spiraea betulifolia var. corymbosa commonly form a patchy, low-shrub layer. The herb layer is open but moderately diverse with drought-tolerant graminoids and forbs.

Comments: Although it has a similar canopy, this association differs significantly from Quercus rubra - Quercus prinus - Carya ovalis / Cercis canadensis / Solidago caesia Forest (CEGL008514) in its understory and herbaceous composition. It occupies drier, steeper sites and lacks (or nearly so) many characteristic low-elevation and mesophytic species of CEGL008514, e.g., Liriodendron tulipifera, Quercus alba, Cercis canadensis, Asimina triloba, Actaea racemosa (= Cimicifuga racemosa), Solidago caesia, Desmodium glutinosum, etc. Conversely, this type contains a number of montane and xerophytic species that are absent or unimportant in CEGL008514.

Range: This community type is currently known from scattered locations on the northern Virginia Blue Ridge, from Warren County south to Bedford County. Occurrences on the Maryland Blue Ridge and in the Ridge and Valley of Virginia, West Virginia, and Maryland are possible and should be sought. Within the known range, this unit can be a large-patch or matrix community type in localities of optimal habitat.

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

TNC Ecoregions: 50:?, 59:C

USFS Ecoregions: M221Aa:C??, M221Ab:C??, M221Da:CCC

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

Synonymy: Quercus prinus - Quercus rubra - Carya ovalis / Solidago (ulmifolia, arguta) - Galium latifolium Forest (Fleming and Coulling 2001) =, Quercus prinus - Quercus rubra - Carya ovalis / Cornus florida / Desmodium nudiflorum Association: Helianthus divaricatus - Carex pensylvanica - Dichanthelium boscii - Arabis laevigata Subassociation, pro parte (Rawinski et al. 1996). see CEGL008515., White Oak - Black Oak - Northern Red Oak: 52 (Eyre 1980) B

References: Eyre 1980, Fleming and Coulling 2001, Fleming et al. 2001, Rawinski et al. 1996

Authors: ECS Confidence: Identifier: CEGL008516

Concept: This community type is currently known from a narrow range in the northern Blue Ridge and adjacent inner Piedmont of Virginia. It is restricted to the western Piedmont foothills and lower-elevation slopes and spurs of the main Blue Ridge. Elevation ranges from 104-719 m (340-2360 feet). Habitats are more-or-less rocky, gentle to steep, submesic slopes with a wide range of aspects. Middle-slope topographic positions are typical, but stands occasionally occur on lower or upper slopes and crests. This association is a true oak-hickory forest with mixed canopy dominance by several Quercus spp. and Carya spp. Carya ovalis, Quercus rubra, and Quercus prinus are consistent codominants and have the highest importance values based on standard forestry statistics generated from stem diameter measurements. Quercus alba, Carya alba, Carya glabra, Fraxinus americana, and Liriodendron tulipifera are less constant canopy species but achieve codominance in some stands. Quercus velutina is a minor canopy associate. Carya spp., Quercus spp., Acer rubrum, Nyssa sylvatica, Fraxinus americana, and Sassafras albidum are well-represented in lower tree strata. Cercis canadensis and, to a lesser extent, Cornus florida dominate the shrub and lowest tree layers, while Viburnum acerifolium is a common low shrub. A large number of herbaceous species occur with low cover in the type.

Comments: In the context of the mountain dataset analyzed here, Desmodium nudiflorum has the highest unscaled adjusted Indicator Value among herbs of this community type. However, plots representing this association were also analyzed in a 477-plot dataset of Piedmont and inner Coastal Plain vegetation, where Desmodium nudiflorum attained much higher indicator status in other vegetation types. Because of these results, Solidago caesia was chosen as a nominal herb for this community, instead of Desmodium nudiflorum.

In recent years, the abundance of Cornus florida has been significantly reduced by mortality resulting from dogwood anthracnose. Some stands of this association have been modified by repeated cutting and are now heavily dominated by Liriodendron tulipifera. Symphoricarpos orbiculatus, Polygonum caespitosum var. longisetum, and exotics such as Ailanthus altissima, Rubus phoenicolasius, and Celastrus orbiculata often become established in canopy gaps following timber harvests or gypsy moth damage.

Range: This community type is currently known from a narrow range in the northern Blue Ridge and adjacent inner Piedmont of Virginia. The type appears to be co-extensive with Catoctin Formation metabasalt (greenstone), a mafic metamorphic rock. Since the Catoctin Formation is well-exposed along the Blue Ridge and western Piedmont of Maryland, the range very likely extends north of Virginia. Within its known distribution, this unit is a matrix community type in localities of optimal habitat and land-use history.

States/Provinces: MD?, VA:S?

TNC Ecoregions: 52:C, 59:C

USFS Ecoregions: 231Ak:CCC, 231Al:CCC, 231Ap:CCC, M221Da:CCC

Federal Lands: NPS (Shenandoah); USFS (George Washington?)

Synonymy: White Oak - Black Oak - Northern Red Oak: 52 (Eyre 1980) B, Quercus rubra - Quercus prinus - Carya ovalis / Cercis canadensis / Solidago caesia Forest (Fleming and Coulling 2001) =

References: Eyre 1980, Fleming and Coulling 2001, Fleming et al. 2001

Authors: G. Fleming, SCS Confidence: Identifier: CEGL008514

- Maryland Vegetation Classification Subset Report I.B. Deciduous forest

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