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A3416 Betula alleghaniensis - Tsuga canadensis Swamp Forest Alliance

Type Concept Sentence: This alliance includes swamp forests of the Northeast, often dominated by Tsuga canadensis, Betula alleghaniensis, and Acer rubrum, with closed to open canopies and an open to dense shrub layer, interspersed with small Sphagnum - herb-dominated depressions, ranging from southeastern Canada through New England to the Central Appalachians, Blue Ridge, and Ridge and Valley. Forests in this alliance are typically at elevations below 1200 m (4000 feet), in poorly drained bottomlands, generally with visible microtopography of ridges and sloughs or depressions. They often occur near streams and are undoubtedly occasionally flooded.

Common (Translated Scientific) Name: Yellow Birch - Eastern Hemlock Swamp Forest Alliance

Colloquial Name: Central Appalachian Hemlock - Hardwood Acidic Swamp Forest

Hierarchy Level:  Alliance

Type Concept: This alliance includes swamp forests of the Great Lakes states and Northeast, ranging from southeastern Canada through New England to the Central Appalachians, Blue Ridge, and Ridge and Valley. Stands are often dominated by Tsuga canadensis, Betula alleghaniensis, and Acer rubrum, with closed to open canopies and an open to dense shrub layer, interspersed with small Sphagnum - herb-dominated depressions. Canopies are composed of various mixtures of evergreen and deciduous species. Minor canopy associates include Acer rubrum, Fraxinus americana, Fraxinus pennsylvanica, Pinus strobus, and Nyssa sylvatica; Liriodendron tulipifera may be a component at the southern limit, while Picea rubens may occur as scattered individuals in the north. Shrubs include Acer pensylvanicum, Alnus incana ssp. rugosa, Hamamelis virginiana, Ilex montana, Ilex verticillata, Kalmia latifolia, Lindera benzoin, Ilex mucronata, Rhododendron maximum, Vaccinium corymbosum, Viburnum lantanoides, and Viburnum nudum var. cassinoides. Herbs in the forested areas include Coptis trifolia, Cornus canadensis, Glyceria melicaria, Lycopodium obscurum, Maianthemum canadense, Onoclea sensibilis, Osmunda regalis var. spectabilis, and Thelypteris noveboracensis. Soils of this alliance vary from saturated muck to imperfectly drained mineral soils and are often acidic. Communities in this alliance occur in upland valleys created by bedrock depressions, on lower slopes, or adjacent to streams and lakes.

Diagnostic Characteristics: Swamp forest dominated by Tsuga canadensis or codominated with Betula alleghaniensis and Acer rubrum.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This alliance includes swamp forests in which Tsuga canadensis can be strongly dominant, causing heavy shade and sparse understory, to those in which there is a substantial deciduous component and well-developed shrub and herb layers.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This swamp forest ranges from strongly coniferous to mixed coniferous-deciduous. The tree canopy is generally closed, but ranges to partially open with numerous canopy gaps. The shrub and herb layers tend to be well-developed, except in cases where Tsuga canadensis is strongly dominant. The nonvascular layer may be poorly to well-developed.

Floristics: This alliance includes palustrine forests, often dominated by Tsuga canadensis and Acer rubrum, with closed to open canopies and an open to dense shrub layer, interspersed with small Sphagnum - herb-dominated depressions. Canopies are composed of various mixtures of evergreen and deciduous species, with canopy dominants varying with elevation. Associates at lower elevations or at the southern end of the range include Acer rubrum, Liriodendron tulipifera, and/or Nyssa sylvatica, while examples at higher elevations or at the northern end of the range are usually dominated by Tsuga canadensis and Betula alleghaniensis with Pinus strobus as an associate. Chamaecyparis thyoides may be a minor component in the eastern portion of the range. The dominant shrubs are usually Corylus cornuta (in the west), Vaccinium corymbosum, Lindera benzoin (in the east and center), Ilex verticillata, Rhododendron maximum, and Kalmia latifolia, but other shrubs can include Acer pensylvanicum, Alnus incana ssp. rugosa, Hamamelis virginiana, Ilex montana, Ilex verticillata, Kalmia latifolia, Lindera benzoin, Ilex mucronata (= Nemopanthus mucronatus), Rhododendron maximum, Vaccinium corymbosum, Viburnum lantanoides, and Viburnum nudum var. cassinoides. Herbs in Sphagnum - herb-dominated openings include Carex folliculata, Carex gynandra, Carex leptalea, Carex scabrata, Carex stricta, Dalibarda repens, Leersia virginica, Osmunda cinnamomea, Sagittaria latifolia (= var. pubescens), Sarracenia purpurea, Solidago patula var. patula, and Symphyotrichum puniceum (= Aster puniceus). Herbs in the forested areas include Coptis trifolia, Cornus canadensis, Glyceria melicaria, Lycopodium obscurum, Maianthemum canadense, Onoclea sensibilis, Osmunda regalis var. spectabilis, Symplocarpus foetidus, Thelypteris noveboracensis, and Trientalis borealis. The nonvascular layer may be poorly to well-developed, and generally characterized by species of Sphagnum, as well as Bazzania trilobata and Pleurozium schreberi.

Dynamics:  In the south, defoliation by the hemlock woolly adelgid (Adelges tsugae) has resulted in 90-100% hemlock mortality, and the virtual elimination of the hemlock component of these swamps. This near-complete removal of Tsuga canadensis from the canopy has led to the release of massive numbers of shrub and birch seedlings in the understory. Tip-up mounds are often created by uprooted trees.
Environmental Description:  Communities in this alliance occur in upland valleys created by bedrock depressions, on lower slopes, or adjacent to streams and lakes. In some cases they are transitional between wetland and upland vegetation. Microtopography is sometimes characterized by mounds and depressions caused by uprooted trees. Soils of this alliance vary from saturated muck to imperfectly drained mineral soils (Kotar et al. 1988) and are often acidic. In the south, sites are usually located in high-elevation valleys or slope concavities, in diffuse stream headwaters and lateral, groundwater-saturated flats along larger streams. Occasionally, stands occupy gentle depressions or basins influenced by seasonally perched groundwater but without flowing streams. Elevation ranges from 670-1200 m (2200-4000 feet), though most occurrences are above 900 m (3000 feet).
Geographic Range: This alliance ranges from the Northern Blue Ridge and Ridge and Valley provinces of Virginia, the high Allegheny Mountains of Virginia and West Virginia, the Maryland Blue Ridge, and the Ridge and Valley of east-central West Virginia, ranging north to the mid-Atlantic and New England states and southeastern Canada, and west to Michigan.

Nations: CA,US

States/Provinces:  CT, MA, MD, ME, MI, NB, NH, NJ, NS?, NY, OH, PA, QC, RI, VA, VT, WV


Confidence Level: Moderate

Confidence Level Comments: No Data Available
Grank: GNR

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.3 Temperate Flooded & Swamp Forest Formation F026 1.B.3
Division 1.B.3.Na Eastern North American-Great Plains Flooded & Swamp Forest Division D011 1.B.3.Na
Macrogroup 1.B.3.Na.2 Pin Oak - Green Ash - Blackgum Swamp Forest Macrogroup M503 1.B.3.Na.2
Group 1.B.3.Na.2.f Red Maple - Blackgum - Green Ash Swamp Forest Group G902 1.B.3.Na.2.f
Alliance A3416 Yellow Birch - Eastern Hemlock Swamp Forest Alliance A3416 1.B.3.Na.2.f
Association CEGL006226 Eastern Hemlock - Yellow Birch / Common Winterberry / Peatmoss species Swamp Forest CEGL006226 1.B.3.Na.2.f
Association CEGL006279 Eastern Hemlock / Great Laurel / Peatmoss species Swamp Forest CEGL006279 1.B.3.Na.2.f
Association CEGL006587 Pitch Pine - Red Spruce / Withe-rod / Peatmoss species Swamp Woodland CEGL006587 1.B.3.Na.2.f
Association CEGL007056 Pitch Pine / Cinnamon Fern - Upright Sedge - Tawny Cottongrass / Peatmoss species Swamp Woodland CEGL007056 1.B.3.Na.2.f
Association CEGL007565 Eastern Hemlock - Red Maple - (Blackgum) / Great Laurel / Peatmoss species Seep Forest CEGL007565 1.B.3.Na.2.f
Association CEGL007853 Red Maple - Blackgum / Common Winterberry - Black Highbush Blueberry / Cinnamon Fern Seep Forest CEGL007853 1.B.3.Na.2.f
Association CEGL008533 Eastern Hemlock - Yellow Birch / Green False Hellebore - Eastern Rough Sedge - Whorled Wood Aster Swamp Forest CEGL008533 1.B.3.Na.2.f
Concept Lineage: A.447 (three of four associations in this old alliance), and two from A.201.

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: No Data Available
Concept Author(s): L. Sneddon et al. (1996) and Midwestern Ecology Group

Author of Description: L. Sneddon

Acknowledgements: No Data Available

Version Date: 01-08-14
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