Common (Translated Scientific) Name: Tuliptree - Sweet Birch - Eastern Hemlock / Great Laurel Forest

Colloquial Name: Southern Appalachian Acidic Cove Forest (Typic Type)

Hierarchy Level:  Association

Type Concept: This association includes hemlock-hardwood forests and acidic cove forests of lower to intermediate elevations in the Southern Blue Ridge, upper Piedmont, Cumberlands, and adjacent areas, ranging from southwestern Virginia and southern West Virginia, south and west to northwestern Georgia. The concept for this association is intended to be broad and cover both mixed stands of evergreen and deciduous hardwoods as well as stands dominated exclusively by deciduous trees in mesic, acidic environments. These communities occur at low to middle elevations (200-1060 m [650-3500 feet]), generally in coves, gorges or sheltered slopes, over acidic soils. The canopy is usually dominated by Liriodendron tulipifera or Betula lenta mixed with Tsuga canadensis, but substantial portions may be comprised mainly of Tsuga canadensis and the occasional Acer rubrum, while other sites may have little or no Tsuga in the canopy. Other deciduous species more typical of "rich" coves may occur as scattered individuals, including Tilia americana var. heterophylla, Acer saccharum, Fraxinus americana, and Fagus grandifolia. Other canopy/subcanopy species often include Quercus alba, Quercus rubra, Magnolia fraseri, and Pinus strobus. Rhododendron maximum is usually dominant in the shrub stratum, often forming impenetrable thickets. South of Virginia, woody associates may also include Ilex opaca var. opaca, Calycanthus floridus, Halesia tetraptera var. tetraptera, and Leucothoe fontanesiana. Herbaceous cover is sparse but can be diverse and is composed of acid-loving species. Typical herbs include Polystichum acrostichoides, Dryopteris intermedia, Dennstaedtia punctilobula, Goodyera pubescens, Mitchella repens, Thelypteris noveboracensis, Galax urceolata, Viola rotundifolia, and Tiarella cordifolia.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Deciduous trees more typical of "rich" coves, such as Aesculus flava, Tilia americana var. heterophylla, and Acer saccharum, are present in this forest only as minor components, if at all. Likewise, rich-site herbs, such as Actaea racemosa, Caulophyllum thalictroides, Actaea pachypoda, and Adiantum pedatum, are absent or nearly so. This forest is distinguished from "northern hardwood forests" by the lack of or near absence of Fagus grandifolia, Betula alleghaniensis, Aesculus flava, and the presence of low-elevation species, such as Betula lenta and Liriodendron tulipifera, and generally by a more depauperate herb layer. There is much variability in species composition in the 43 plots classified as this association from the Appalachian Trail region (Fleming and Patterson 2009a), but constancy of the nominal species was quite high (>84%). The most constant species (>64%), in order of descending constancy, are Rhododendron maximum, Tsuga canadensis, Betula lenta, Acer rubrum, Liriodendron tulipifera, Quercus rubra, Mitchella repens, Polystichum acrostichoides, and Hamamelis virginiana. Species richness in 400-m2 plots ranges from 11 to 72 species per plot. This variable richness is probably influenced by somewhat variable soil fertility and the variation in cover/density of evergreen Rhododendron shrub colonies. An interesting example from the Piedmont/Blue Ridge transition of Georgia (Cedar Creek Canyon, Chattahoochee National Forest) has high coverage of Rhododendron minus and other foothills/Piedmont species such as Liquidambar styraciflua and Aesculus sylvatica.

In the 900- to 1060-m (3000-3500 feet) elevational range, the type becomes transitional to ~Betula alleghaniensis - (Tsuga canadensis) / Rhododendron maximum / (Leucothoe fontanesiana) Forest (CEGL007861)$$, which lacks lower-elevation species such as Liriodendron tulipifera and Galax urceolata, and contains many species characteristic of higher elevations and northern latitudes.

Similar vegetation has been observed in coves of the Cumberland Mountains of southwestern Virginia (e.g., Clinch Ranger District: Dark Hollow, Roaring Branch, Pick Breeches and Flannery Ridges,) but comprehensive data are needed to determine whether these stands are part of this forest types or transitional to ~Tsuga canadensis - (Fagus grandifolia, Tilia americana var. heterophylla) / Magnolia tripetala Forest (CEGL008407)$$. The latter unit apparently has an extensive distribution in the Cumberland Plateau of Kentucky and Tennessee, the Southern Ridge and Valley of Tennessee, and the Central Appalachians of West Virginia and southwestern Pennsylvania.

In West Virginia, 45 plots, mostly from New River Gorge National River and Gauley River National Recreation Area, are classified to this association. Outliers at lower elevations on the western flanks of the Allegheny Mountains are also classified here (with less confidence) based on high cover by Rhododendron maximum, which is uncommon in related ~Tsuga canadensis - Fagus grandifolia - Acer saccharum / (Hamamelis virginiana, Kalmia latifolia) Forest (CEGL005043)$$ typical of the Western Allegheny Plateau, and lack of high-elevation associates found in ~Tsuga canadensis - Betula alleghaniensis - Prunus serotina / Rhododendron maximum Forest (CEGL006206)$$ of high elevations in the Allegheny Mountains. West Virginia examples of this association (CEGL007543) include stands with mixed hemlock-deciduous canopies and stands with deciduous canopies, often with hemlock in the lower strata. Fagus grandifolia is not uncommon in WV stands.

Similar NVC Types: No Data Available

note: No Data Available