Bald Cypress-Tupelo Gum Swamp - Code: Ne3A

One of the most visually distinctive habitats in the Nearctic, Cypress-Tupelo Gum Swamp is often the first image that comes to mind when one pictures the se. United States. Dominated by tall, broad-based, epiphyte-laden trees, the canopy is typically dense and reaches heights of 60–100 ft. (18–30m), though Bald Cypress (Taxodium distichum) can be as tall as 145 ft. (44m).  Cypress–tupelo gum swamps grow in hot, humid environments that typically receive 35–65 in. (900–1,650mm) of rainfall per year. This habitat occurs along the floodplains of blackwater streams originating in the coastal plain or as cypress domes in the middle of open wetlands. The ground is permanently or seasonally flooded, and the maze of back channels is best explored by canoe or boardwalk. 

This is an entirely deciduous forest, where even the conifers lose their needles in winter. The majority of the canopy is composed of Bald Cypress and either Water Tupelo (Nyssa aquatica) or Swamp Tupelo (Nyssa biflora), though Water Hickory (Carya aquatica) is occasionally co-dominant. Bald Cypress and Water Tupelo are both extremely broad-based trees with tapered trunks, and Bald Cypress can be as stout as 39 ft. (12m) in diameter. The mid-story in these forests is generally sparse and consists of young tupelos and smaller, shade-tolerant trees like Red Maple (Acer rubrum), Pop Ash (Fraxinus caroliniana) and Green Ash (Fraxinus pennsylvanica). Vines are a common feature of the mid-story and may be abundant. Epiphytes, including large bromeliads, orchids and especially Spanish Moss (Tillandsia usneoides) are prevalent in the canopy and midstory. 

The understory is the most variable element and is dependent mostly on depth and variability of water levels. Frequently, the understory is entirely flooded seasonally, and apart from some aquatic vegetation, the only noticeable feature is the protruding “cypress knees,” woody root projections whose purpose is not well understood. In seasonally dry forests, the understory can be extremely lush, dominated by rapidly growing plants tolerant of wet soil. Giant Sedge (Carex pendula), False Nettle (Boehmeria cylindrica), Lizard’s Tail (Saururus cernuus), and Greater Marsh St.-John’s-wort (Hypericum virginicum) grow in areas that are flooded for much of the year, while relatively drier areas have Swamp Fern (Acrostichum aureum), False Pimpernel (Lindernia dubia), and Camphorweed (Heterotheca subaxillaris) and woody shrubs like Buttonbush (Cephalanthus occidentalis), willows (Salix spp.),  azaleas (Rhododendron spp.), sweet pepperbush (Clethra alnifolia), Northern arrow-wood (Viburnum recognitum), and Virginia Sweetspire (Itea virginica).  Cinnamon fern (Osmundastrum cinnamomeum) can also be abundant.

These swamps naturally exist as a diverse multi-age system with major disturbance events coming in the form of violent storms, windthrow, and exceptional flooding.  Fire is a rare but important part of this habitat. Drought events expose dry land and fires clear old forest allowing for the germination of new trees.