Pine / Scrub Oak Sandhills
Sand ridges of the southeastern Virginia Coastal Plain support pyrophytic mixed woodlands of pines, scrub oaks, ericaceous shrubs, and light-demanding herbaceous xerophytes. Communities in this group reach their northern range limit in Virginia, where they occur in small, highly localized patches. Similar vegetation ranges through the southeastern Coastal Plain to Texas. Suitable habitats are located primarily on slightly elevated sand deposits stretching along the eastern sides of the Blackwater and Nottoway Rivers in Sussex, Southampton, and Isle of Wight Counties and the City of Suffolk. Soils are coarse xeric sands, often overlying clay-rich subsoils that may perch water briefly and limit rooting depths. The original vegetation of these sites is presumed to have been composed of open overstories of longleaf pine (Pinus palustris), perhaps in mixtures with pond pine (Pinus serotina) and loblolly pine (Pinus taeda) at the northern end of its range, with open understories of scrub oaks (Quercus spp.), patchy ericads, and areas of open sand with sparse herbaceous cover. Stand structure and successful reproduction of longleaf pine were presumably controlled by a natural regime of frequent low-intensity fires. Extant examples have been altered by heavy cutting and decades of fire exclusion. Longleaf pine has been almost entirely replaced by loblolly pine (Pinus taeda), and most stands are now quite closed. Various combinations of turkey oak (Quercus laevis), sand post oak (Quercus margaettiae), water oak (Quercus nigra), bluejack oak (Quercus incana), southern red oak (Quercus falcata), blackjack oak (Quercus marilandica var. marilandica), and sand hickory (Carya pallida) occur as overstory co-dominants and understory trees.
On the most elevated and xeric sites, frequent shrubs include poison oak (Toxicodendron pubescens), farkleberry (Vaccinium arboreum), deerberry (Vaccinium stamineum) and dwarf wax myrtle (Morella pumila). Characteristic herbaceous xerophytes, which may be almost eliminated by canopy closure and accumulations of thick leaf litter, include silvery bluestem (Andropogon ternarius var. ternarius), woolly three-awn grass (Aristida lanosa), hairsedges (Bulbostylis ciliatifolia and Bulbostylis coarctata), grass-like roselings (Callisia graminea), spurge-nettle (Cnidoscolus stimulosus), pineland tick-trefoil (Desmodium strictum), American ipecac (Euphorbia ipecacuanhae), sundial lupine (Lupinus perennis), October-flower (Polygonella polygama var. polygama), wavy-leaf noseburn (Tragia urens), and Baldwin's nailwort (Paronychia baldwinii ssp. riparia).
On sandy flats associated with the sandhills, soils may have seasonally perched water tables but are primarily well-drained and dry for substantial periods of the year. Here, the best extant fragments are dominated by mixed stands of longleaf, loblolly, and pond pines, with a scattered understory of turkey oak. Dense, mostly ericaceous shrub layers of sheep laurel (Kalmia angustifolia) or Carolina laurel (Kalmia carolina), huckleberries (Gaylussacia frondosa, Gaylussacia dumosa var. dumosa, and Gaylussacia baccata), staggerbush (Lyonia mariana), small black blueberry (Vaccinium tenellum), creeping blueberry (Vaccinium crassifolium), inkberry (Ilex glabra), Canadian serviceberry (Amelanchier canadensis), and switch cane (Arundinaria tecta) are characteristic. Herbs are generally sparse, but include southern bracken fern (Pteridium aquilinum ssp. pseudocaudatum), common pyxie-moss (Pyxidanthera barbulata var. barbulata), chaffheads (Carphephorus bellidifolius and Carphephorus tomentosus), and fasciculate beaksedge (Rhynchospora fascicularis).Despite past and ongoing disturbances, pine / scrub oak sandhills are important communities for conservation and restoration in Virginia because of their regional rarity. Virginia's examples, along with those in northeastern North Carolina, lack wiregrass (Aristida stricta and Aristida beyrichiana) and other pyrophytic grasses characteristic of similar communities further south and are thus thought to represent a rare compositional variant. Stands at Blackwater Ecological Preserve (near Zuni, Isle of Wight County) and the adjacent DCR Antioch Pines Natural Area Preserve are being managed with prescribed burning, but the remaining occurrences are in critical need of protection and restoration.
References: Frost and Musselman (1987), Plocher (1999).
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Longleaf pine (Pinus palustris), switch cane (Arundinaria tecta , in foreground), and huckleberries (Gaylussacia spp., with red foliage) at Blackwater Ecological Preserve, Isle of Wight County. Photo © Gary P. Fleming.
Prescribed burning is being used in Virginia to restore Pine / Scrub Oak Sandhills, which originally developed under a regime of frequent, low intensity fires. Blackwater Ecological Preserve, Isle of Wight County. Photo: Sandra Y. Erdle.