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upland depression swamp forest

Sites

Poorly drained upland flats or depressions. Usually on broad upland flats but occasionally on high ridge tops.

Soils

Various soils with drainage hindered by a clay hardpan or by shallow rock. Soil series include Iredell.

Hydrology

Palustrine, seasonally to intermittently flooded or saturated. During dry periods water may be unavailable to plants because of restricted rooting depth and because the impermeable layer has kept the subsoil dry.

Vegetation

Canopy

Forest canopy usually dominated by Quercus phellos (Willow Oak), sometimes codominant with or replaced by Q. lyrata (Overcup Oak), Q. michauxii (Basket Oak), Q. bicolor (Swamp White Oak) or Liquidambar styraciflua (Sweet Gum). Other trees may be present, including Ulmus alata (Winged Elm), Nyssa sylvatica (Black Gum), Acer rubrum (Eastern Red Maple), Diospyros virginiana (American Persimmon), Liriodendron tulipifera (Tulip-tree), Carya ovata (Common Shagbark Hickory) and occasional upland trees, particularly Quercus stellata (Post Oak) and Carya carolinae-septentrionalis (Carolina Shagbark Hickory).

Understory

Shrubs are usually sparse. Species may include Vaccinium fuscatum (Hairy Highbush Blueberry), Cephalanthus occidentalis (Buttonbush), Ilex decidua (Possum-haw) and Viburnum dentatum (Arrow-wood). Vines include Smilax spp. (Greenbrier), Campsis radicans (Trumpet-creeper), Vitis rotundifolia (Muscadine) and Toxicodendron radicans (Eastern Poison Ivy).

Herb Layer

Herbs are usually sparse, with Carex (Sedge) species common, along with Juncus effusus (Common Rush), Eleocharis tenuis (Slender Spikerush), Selaginella apoda (Meadow Spikemoss) and various bottomland spring ephemerals such as Claytonia virginica (Spring-beauty). The mosses Climacium americanum (Tree Moss) and Sphagnum lescurii (Lescur’s Sphagnum) are often abundant.

Dynamics

These communities are generally stable climaxes, maintained by their hydrology. They may be susceptible to disturbance caused by unusually prolonged flooding or by drought. Liquidambar styraciflua is often present in Upland Depression Swamp Forests and sometimes comes to dominate or codominate after major disturbances such as logging.

Associations

Typically associated with Xeric Hardpan Forest and Basic Oak-Hickory Forest but may grade into other upland forest types. Sometimes occurs with Upland Pools.

Comments

Sites which hold enough standing water seasonally may be important breeding sites for amphibians. Upland Depression Swamp Forests are part of a characteristic suite of communities on mafic igneous or metamorphic rock, along with Xeric Hardpan Forest and Basic Oak-Hickory Forest. The high base levels in mafic rocks contribute to the formation of montmorillonite clays which inhibit drainage. Upland Depression Swamp Forests also form over acidic shales, and occasionally on harder rocks.