By Drew Chaney, Center for Urban Habitats
Overview
Basic Piedmont Prairies/Savannas are found on uplands with a higher base saturation than their acidic counterparts, occurring over diabase, amphibolite, greenstone and base-rich gneisses and schists. Sites typically occur in powerline rights-of-way, roadsides, and old fields. Soils are typically shallow, rocky, and typically clayey or sandy. The levels of base cations that are available to plants is high in these soils, and allows for greater species richness and a strong basophilic component to the flora. Soil pH is typically somewhat acidic to neutral, similar to their Basic Oak-Hickory Forest equivalents. Basic Prairies/Savannas, as well as other Piedmont grassland remnants, occur over unplowed soils, as the fungal layer necessary for germination of many species does not persist after subsurface disturbances.
Basic Piedmont Prairies/Savannas are widely scattered across the Piedmont over suitable geologic formations, and intact examples are less frequent than Acidic Prairies due to the long history of agriculture on these geologies, as well as their greater capacity for exotic species recruitment.
Vegetation
Basic Prairies/Savannas are characterized by their predominance of warm-season grasses mixed with a great diversity of nutrient-demanding and more generalist forbs. Characteristic graminoids of this community type include little bluestem (Schizachyrium scoparium), Elliott’s bluestem (Andropogon gyrans), broomsedge (Andropogon virginicus), splitbeard bluestem (Andropogon ternarius), yellow prairie grass (Sorghastrum nutans), poverty oatgrass (Danthonia spicata), purple three-awn grass (Aristida purpurascens), purple lovegrass (Eragrostis spectabilis), beaked panic grass (Coleataenia anceps), and little-headed nutrush (Scleria oligantha). The latter is especially frequent in more hardpan soils over mafic rocks. Dichanthelium diversity is high, with species such as D. laxiflorum, D. boscii, D. linearifolium, and D. ravenelii (latter in the southeastern Piedmont only) often present alongside more generalist species.
Characteristic forbs include a wide variety of conservative generalist and basophilic heliophytes, particularly goldenrods (Solidago nemoralis, juncea, pinetorum), thoroughworts (Eupatorium spp., especially E. altissimum, E. saltuense, E. godfreyanum, and E. hyssopifolium), narrow-leaved mountain-mint (Pycnanthemum tenuifolium), pussytoes (Antennaria parlinii and A. plantaginifolia), hairy angelica (Angelica venenosa), Small’s ragwort (Packera anonyma), rosin weed (Silphium asteriscus), scaly blazing star (Liatris squarrosa), upland ironweed (Vernonia glauca), green milkweed (Asclepias viridiflora), common rose-pink (Sabatia angularis), Carolina wild-petunia (Ruellia caroliniensis), yellow flax (Linum medium var. texanum), pinweeds (Lechea spp.), lyreleaf sage (Salvia lyrata), and curlyheads (Clematis ochroleuca), as well as a wide variety of Fabaceae including high diversity in tick-trefoils (Desmodium spp, especially D. viridiflorum, D. obtusum, D. nuttallii.) and bushclovers (Lespedeza spp.), as well as rattlebox (Crotalaria sagittalis), pencilflower (Stylosanthes biflora), pink wild bean (Strophostyles umbellata), and downy milkpea (Galactia regularis).
While not a dominant part of this community, woody species are present in Basic Prairies/Savannas, though their development is limited by disturbance regimes such as mowing and fire (prescribed and natural). Shrub species like Carolina rose (Rosa carolina), blackhaw (Viburnum prunifolium), New Jersey tea (Ceanothus americanus), winged sumac (Rhus copallinum), and dwarf hawthorn (Crataegus uniflora) are commonly found, as well as seedlings of tree species such as oaks (Quercus alba, Q. falcata, Q. phellos Q. velutina, Q. stellata), hickories (Carya tomentosa, glabra, ovalis, cordiformis), white ash (Fraxinus americana), hackberry (Celtis occidentalis), eastern redcedar (Juniperus virginiana), and redbud (Cercis canadensis). Ericaceous shrubs such as hillside blueberry (Vaccinium pallidum) and deerberry (V. stamineum) can be present, but are rarely prolific.
Several Piedmont, state and globally rare species occur in Basic Prairies, including climbing and old-field milkvines (Matelea obliqua and M. decipiens), rattlesnake master (Eryngium yuccifolium), tall and Piedmont Barbara’s-buttons (Marshallia legrandii and M. obovata), glade wild quinine (Parthenium auriculatum), smooth coneflower (Echinacea laevigata), stiff goldenrod (Solidago rigida), dwarf chinquapin oak (Quercus prinoides), Carolina thistle (Cirsium carolinianum), tall dropseed (Sporobolus compositus), short-leaf beardgrass (Gymnopogon brevifolius), Torrey’s mountain-mint (Pycnanthemum torreyi), Harvey’s beaksedge (Rhynchospora harveyi), Mead’s sedge (Carex meadii), eastern prairie anemone (Anemone berlandieri), ringed panic grass (Dichanthelium annulum), Harvill’s panic grass (Dichanthelium harvilii), and American ipecac (Gillenia stipulata).
Definitions
Mafic: a rock with large proportions of minerals rich in magnesium and iron (Ma+Fe = Mafic) such as amphibole, epidote and pyroxene.
Basophile: a plant species restricted to or preferring soils high in base cations.
Base cations: the soil-borne elements calcium, magnesium, potassium, and sodium, most of which are essential for plant growth. Heavily weathered soils will tend to have fewer of these nutrients and to be more acidic.
Heliophyte: a plant species requiring high levels of sunlight.
Graminoid: a member of the grass (Poaceae), sedge (Cyperaceae), or rush (Juncaceae) families.
Conservative species: a species that is restricted to high-quality, relatively undisturbed natural ecosystems.
