Acidic Cove Forests
This group contains mixed hardwood and hardwood-hemlock forests of infertile, mesic, montane habitats. In Virginia, these forests occur extensively throughout the mountains, occupying moist lower slopes, ravines, and coves underlain by sandstone, quartzite, granite, and other acidic bedrock. Typical overstory trees include tulip-tree (Liriodendron tulipifera), eastern hemlock (Tsuga canadensis), red maple (Acer rubrum), sweet birch (Betula lenta var. lenta), eastern white pine (Pinus strobus), cucumber magnolia (Magnolia acuminata), and Fraser magnolia (Magnolia fraseri) in variable mixtures. Although less frequent, American beech (Fagus grandifolia) is also an important overstory tree in some stands, particularly in the Cumberland Mountains.
Dense, evergreen shrub layers of great rhododendron (Rhododendron maximum) are characteristic, although spotty in northwestern Virginia and largely absent from the northern Blue Ridge. On the southern half of the northern Blue Ridge, Catawba rhododendron (Rhododendron catawbiense) is often abundant on sites where great rhododendron is scarce. Other frequent shrubs include mountain laurel (Kalmia latifolia), witch hazel (Hamamelis virginiana var. virginiana), maple-leaf viburnum (Viburnum acerifolium), and mountain pepper-bush (Clethra acuminata, in southwest Virginia only). Herbaceous species, limited by dense shade and poor soils, are sparser and less diverse than in fertile cove habitats. Nevertheless, some Acidic Cove Forests have an "evergreen-lush" herb layer, with species such as galax (Galax urceolata) and Christmas fern (Polystichum acrostichoides) forming large colonies. The small orchid Appalachian twayblade (Listera smallii) frequently grows in deep shade under rhododendrons in these communities.
Composition of these forests appears to vary with elevation and physiographic region. They are closely related to communities of the Eastern Hemlock - Hardwood Forests ecological group, but generally have more diverse composition of woody species and considerably higher species richness. The hemlock component has been further reduced by past logging and, more recently, by outbreaks of the hemlock woolly adelgid (Adelges tsugae), an introduced insect pest.
References: Stephenson and Adams (1991), Coulling and Rawinski (1999), Fleming and Coulling (2001), Fleming and Moorhead (1996), Fleming and Moorhead (2000), Rawinski et al. (1996).
Click on the images below to open a larger image in a separate window.
|A typical Southern Appalachian Acidic Cove Forest in the Iron Mountains, Smyth County (George Washington and Jefferson National Forests). Great rhododendron (Rhododendron maximum) forms thick shrub tangles under a mixed overstory of red maple (Acer rubrum), sweet birch (Betula lenta var. lenta), tulip-tree (Liriodendron tulipifera), Fraser magnolia (Magnolia fraseri), and some eastern hemlock (Tsuga canadensis). Photo © Gary P. Fleming||Catawba rhododendron (Rhododendron catawbiense) is often abundant in acidic cove forests of the northern Blue Ridge, where great rhododendron (R. maximum) is mostly absent. Riprap Hollow, Augusta County (Shenandoah National Park). Gary P. Fleming / © DCR Natural Heritage.|
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