Bald Cypress - Tupelo Swamps
Forests in this group occupy seasonally to semipermanently flooded backswamps, sloughs, and poorly drained first bottoms of Coastal Plain rivers and streams. These swamp forests occur throughout the Coastal Plain from Delaware south to Florida and west to eastern Texas, and in the Mississippi River alluvial basin north to Kentucky. They are generally distributed throughout southeastern Virginia, north to Dragon Swamp (Gloucester, King and Queen, and Middlesex Counties), with small-stream swamp tupelo (Nyssa biflora) swamps extending somewhat further north. Habitats are deeply flooded (up to 1.3 m) for part of the year; many retain at least some standing water throughout the growing season. Microtopography is often pronounced with small channels, swales, tree-base hummocks, and numerous bald cypress "knees." Overstory composition varies from mixed stands of bald cypress (Taxodium distichum), water tupelo (Nyssa aquatica), and/or swamp tupelo (Nyssa biflora) to nearly pure stands of one species or another. The three dominants have complex competitive and successional relationships. As a rule, the two tupelos are less shade-tolerant than bald cypress and regenerate more readily by sprouting in cut-over stands. Thus, tupelos tend to become dominant when bald cypress stands are heavily logged. In addition, swamp tupelo appears to be most abundant in organic swamp soils, while water tupelo appears to prefer mineral soils with high silt content.Stands dominated primarily or exclusively by swamp tupelo typically occur in the most acidic soils with highest organic content, usually in the smaller swamps along headwaters streams of the inner Coastal Plain.
Green ash (Fraxinus pennsylvanica), overcup oak (Quercus lyrata), American elm (Ulmus americana), and red maple (Acer rubrum) are occasional overstory associates and frequent understory trees; swamp cottonwood (Populus heterophylla) is also an occasional overstory associate and often abundant in disturbed or cut-over stands. Carolina ash (Fraxinus caroliniana) is often dominant in the small tree and shrub layers, while vines of climbing hydrangea (Decumaria barbara) and coral greenbrier (Smilax walteri) are often abundant.
Herb layers vary from sparse to seasonally lush. Most herbaceous plants of bald cypress-tupelo swamps are tolerant of muck soils and fluctuating water levels, or are capable of becoming established on tree hummocks, stumps, and logs. A few of the typical herbs are lizard's-tail (Saururus cernuus), false nettle (Boehmeria cylindrica), greater marsh St. John's-wort (Hypericum walteri), small beggar-ticks (Bidens discoidea), weak stellate sedge (Carex seorsa), giant sedge (Carex gigantea), taper-leaf water horehound (Lycopus rubellus), catchfly cutgrass (Leersia lenticularis), and pale mannagrass (Torreyochloa pallida). Draw-down zones may support large populations of false pimpernel (Lindernia dubia var. dubia), camphorweed (Pluchea camphorata), water paspalum (Paspalum fluitans), Carolina doll's-daisy (Boltonia caroliniana), and other fast-growing herbs.
This group differs from Coastal Plain / Piedmont Swamp Forests in the clear dominance or co-dominance of bald cypress and tupelos (vs. dominance of mixed hardwoods) and apparently by longer hydroperiods and more deeply flooded habitats. It is distinguished from Non-Riverine Swamp Forests, which are also dominated by bald cypress and tupelos, by habitat (floodplains vs. non-riverine peatlands) and lower-strata floristics. Although community types in this group are relatively common in southeastern Virginia, high-quality examples are scarce and all stands provide valuable wildlife habitat and resources. Mature, hollow specimens of the dominant trees are known to provide nesting habitats for the globally uncommon, state-rare eastern big-eared bat (Corynorhinus rafinesquii macrotis) and southeastern myotis (Myotis austroriparius). Old-growth stands of bald cypress-dominated swamp with trees up to 800 years old occur along the Blackwater River in Surry and Isle of Wight Counties. However, the largest individuals of both bald cypress and water tupelo occur in swamps along the Nottoway River in Southampton County.References: Fleming and Moorhead (1998), Parker and Wyatt (1975), Plunkett and Hall (1995).
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Well developed bald cypress "knees" line the Chickahominy River at the edge of a swamp near Providence Forge, New Kent County (Game Farm Marsh Wildlife Management Area). Photo: © Gary P. Fleming
Even-aged stand of water tupelo (Nyssa aquatica) in a swamp along the Blackwater River, Surry County. Photo: Katharine Derge / © DCR Natural Heritage.
Dense bald cypress (Taxodium distichum) forest in Carbell Swamp, Isle of Wight County. Photo: Gary P. Fleming / © DCR Natural Heritage.
Old-age bald cypress (Taxodium distichum) trees on the Blackwater River have been aged at 600 to 800 years old (Dendron Swamp Natural Area Preserve). Photo: Irvine Wilson / © DCR Natural Heritage.
Old-growth water tupelo (Nyssa aquatica) and bald cypress (Taxodium distichum) in a Nottoway River Swamp, Southampton County. Photo: Gary P. Fleming / © DCR Natural Heritage.
Old-age water tupelo (Nyssa aquatica) stand, Nottoway River near Courtland. Photo: Gary P. Fleming / © DCR Natural Heritage.