Mountain / Piedmont Basic Woodlands
This group is represented by deciduous and mixed woodlands of xeric, rocky habitats over mafic substrates such as diabase, gabbro, metabasalt (greenstone), and amphibolite. A few examples occur in habitats underlain by base-rich granite, calcareous shale, and calcareous sandstone. Occurrences in Virginia are widely and locally scattered throughout the mountains and Piedmont, often occurring in patch-mosaics with exposed outcrop barrens. They are most frequent (but still very local) in metabasalt districts of the northern Blue Ridge. Habitats are situated on south- to west-facing slopes with numerous outcrops and shallow, rocky soils that are dry but relatively fertile, with moderate to high levels of calcium and magnesium.
Although oaks (Quercus spp.) are frequent (sometimes co-dominant) components, these woodlands are more often dominated by variable mixtures of white ash (Fraxinus americana) and hickories (Carya spp.), often with eastern red cedar (Juniperus virginiana var. virginiana) or Virginia pine (Pinus virginiana) as a major associate. Trees are usually stunted and form an open or sparse overstory. Typical understory trees and shrubs include eastern redbud (Cercis canadensis var. canadensis), eastern hophornbeam (Ostrya virginiana), ninebark (Physocarpus opulifolius var. opulifolius), slippery elm (Ulmus rubra), aromatic sumac (Rhus aromatica var. aromatica), hackberries (Celtis occidentalis and Celtis tenuifolia), hoptree (Ptelea trifoliata var. trifoliata), and pasture rose (Rosa carolina var. carolina). These woodlands contain a surprisingly diverse array of herbaceous graminoids and forbs; a few of the more widespread, representative species are cliff muhly (Muhlenbergia sobolifera), elm-leaved goldenrod (Solidago ulmifolia var. ulmifolia), bottlebrush grass (Elymus hystrix var. hystrix), Pennsylvania sedge (Carex pensylvanica), woodland sunflower (Helianthus divaricatus), Appalachian phacelia (Phacelia dubia var. dubia), hoary mountain-mint (Pycnanthemum incanum var. incanum), smooth blue asters (Symphyotrichum laeve var. laeve and var. concinnum), Virginia spiderwort (Tradescantia virginiana), and narrow-leaved vervain (Verbena simplex). Unusual stands that occur on concave slopes at two sites have herb layers dominated by river-oats (Chasmanthium latifolium).
Mountain / Piedmont Basic Woodlands are similar to Montane Dry Calcareous Forests and Woodlands but generally lack the latter group's characteristic calciphilic species such as chinkapin oak (Quercus muhlenbergii), black maple (Acer nigrum), Carolina buckthorn (Frangula caroliniana), and American beakgrain (Diarrhena americana). Most Virginia stands of Mountain / Piedmont Basic Woodland represent a single, state and globally rare community type. There are few threats, although the shrub coralberry (Symphoricarpos orbiculatus), introduced from farther west, is a troublesome invasive in some stands.References: Coulling and Rawinski (1999), Fleming (2002a), Fleming and Coulling (2001), Fleming et al. (2007), Rawinski et al . (1996).
Click on the images below to open a larger image in a separate window.
|Mountain / Piedmont Basic Woodland on a metabasalt (greenstone) slope of the northern Blue Ridge, Albemarle County (Shenandoah National Park). Gary P. Fleming / © DCR Natural Heritage.|
|Woodland sunflower (Helianthus divaricatus), hoary mountain-mint (Pycnanthemum incanum), and wild quinine (Parthenium integrifolium var. integrifolium) dominate the mid-summer herb layer of a basic woodland near Lewis Spring Falls (Shenandoah National Park). Gary P. Fleming / © DCR Natural Heritage.|
|A woodland of ashes (Fraxinus americana , turning reddish) and hickories (Carya spp., turning yellow) forms a matrix around exposed metabasalt (greenstone) cliffs on the flanks of Big Devils Stairs in the northern Blue Ridge (Shenandoah National Park). Photo: Gary P. Fleming|
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