Calcareous Spring Marshes and Muck Fens
This group contains herbaceous wetlands of calcareous, groundwater-saturated sloughs, abandoned meanders, depressions, and spring overflows on large stream or river floodplain terraces. Restricted to a few sites in carbonate rock districts of the Ridge and Valley region, these very rare habitats are highly threatened by impoundments and hydrological alterations, grazing, and agricultural pollution. Deep, hydric muck soils have high calcium levels and are more or less permanently saturated or flooded by perched groundwater or seepage inputs. Vegetation is marsh-like and characterized by coarse emergent species: arrow-arum (Peltandra virginica), bur-reeds (Sparganium eurycarpum and Sparganium americanum), water smartweed (Polygonum amphibium var. emersum), lake-bank sedge (Carex lacustris), hop sedge (Carex lupulina), Emory's sedge (Carex emoryi), hairy-fruit sedge (Carex trichocarpa), Virginia cutgrass (Leersia virginica), smooth bur-marigold (Bidens laevis), sweetflag (Acorus calamus), marsh-marigold (Caltha palustris), skunk-cabbage (Symplocarpus foetidus), spotted jewelweed (Impatiens capensis), blueflag iris (Iris versicolor), and broad-leaved cattail (Typha latifolia). Buckbean (Menyanthes trifoliata) and water horsetail (Equisetum fluviatile), both very rare species in Virginia, are components at two sites each. A most unusual site in Clarke County consists of a 2 ha (5 ac) marsh developed in the overflow of powerful artesian springs. The marsh here is dominated by broad-leaved cattail and the state-rare, northern disjunct beaked sedge (Carex utriculata), while deep channels support the similarly disjunct flatstem pondweed (Potamogeton zosteriformis). Although two occurrences of this community group are located on natural area preserves, several others remain unprotected and vulnerable.
References: Hunsucker and Mueller (1998).
Click on the images below to open a larger image in a separate window.Calcareous marsh at the foot of a limestone hillside along Folly Mills Creek in Augusta County (Folly Mills Creek Fen Natural Area Preserve). Marsh vegetation dominated by broad-leaved cattail (Typha latifolia) and skunk-cabbage (Symplocarpus foetidus) gives way to sedge-dominated wet prairie on the right. See reference cited above.Photo: Gary P. Fleming Calcareous marsh dominated by broad-leaved cattail (Typha latifolia) and beaked sedge (Carex utriculata), a rare northern disjunct in Virginia. The habitat is a massive spring complex along a tributary of Long Marsh Run in the Ridge and Valley region of Clarke County. Gary P. Fleming / © DCR Natural Heritage.