Environmental Description:  Stands are found in a variety of wetland settings, including seasonally to annually saturated or flooded soils, or standing water. A summary of the range of variation for the various wetlands within the subclass is provided in Table 1.

Table 1. Major wetland types used to guide formation distinctions. Types and definitions are adapted from the National Wetlands Working Group (1997) and Mackenzie and Moran (2004), but need further review for tropical summaries.

Wetland Type	Definition	Environmental features	Growth forms	Mitsch & Gosselink (2000) type
Bog	Bogs are shrubby, nutrient-poor peatlands with distinctive communities of ericaceous shrubs and hummock-forming Sphagnum species, sometimes with sedges, adapted to high acid and oxygen-poor soil conditions. Trees >2 m have <10% cover (rarely, raised bogs may contain some forested stands). Vegetation of bogs and poor fen often overlap and are sometimes treated together as "acid peatland."	+/- ombrotrophic pH <4.5 >40 cm fibric/mesic peat.	Stunted (<2 m tall) needle-leaved tree, stunted broad-leaved tree, low shrub, dwarf-shrub (ericaceous), sphagnum.	Peatland
Fen	Fens are peatlands where groundwater inflow maintains relatively moderate to high mineral content within the rooting zone. Sites are characterized by non-ericaceous shrubs, sedges, grasses, reeds, and brown mosses (often with sphagnum). Ranges from poor fen to rich fen. Poor fens overlap with bogs and are sometimes treated as "acid peatland" separate from "alkaline peatland."	Groundwater-fed pH >4.5 (approximate ranges include poor fen 4.5-5.5, medium or intermediate fen 5.5-6.5, rich fen 6.5-7.5 and extremely rich fen >7.5). >40 cm fibric/mesic peat.	Low shrub (often non-ericaceous, but evergreen), sedge (often fine), grass, reed, and brown moss, often with sphagnum.	Peatland
Freshwater Marsh, Wet Meadow & Shrubland	A marsh-wet meadow is a shallowly flooded or saturated wetland dominated by emergent grass-like vegetation. A fluctuating water table is typical in marshes and wet meadows, with early season high water tables and some flooding dropping through the growing (or dry) season, and exposure of the substrate or drying of the profile possible in late (or high of dry) season or drought years. Shrub wetlands (shrub carrs) occupy similar sites to wet meadows.	Mineral soils or well-humified peat. Protracted shallow flooding (0.1 to 2.0 m) or prolonged soil profile saturation.	Grass, sedge (often coarse), forb, low shrub, tall shrub.	Freshwater marshes Tidal freshwater marshes Riparian ecosystem (wetland, herb/shrub)
Salt Marsh	Saltwater marshes are intertidal to supratidal ecosystems that are flooded diurnally (or less), sometimes with freshwater inputs, and has communities dominated by salt-tolerant emergent graminoids and succulents.	Intertidal and supratidal zones, semi-diurnal to diurnal, flooding by brackish or saltwater [n.b. inland non-tidal saline wet meadows may also be placed here].	Grass, sedge, forb, halophytic (succulent) forb, halophytic shrub.	Tidal salt marshes
Wetlands Treated Elsewhere
Flooded & Swamp Forests (I.A.4, I.B.3, I.B.5)	A swamp forest is a tree-dominated mineral or peat wetland, on sites with a flowing/flooded or fluctuating semipermanent, near- or at-surface water table. A flooded forest occurs on sites where flooding varies from temporary (<7 days) to semipermanent (>180 days).	Mineral soils or well-humified peat, temporary to semipermanent flooding (0.1 to 2 m deep), rarely saline	Broad-leaved tree, needle-leaved tree, tall shrub, forb, graminoid, hydromorphic herb (rarely), trees >10% cover.	Freshwater swamps Riparian ecosystems (wetland, tree)
Mangrove (I.A.5)	Mangroves occur in the intertidal and brackish backwater of estuarine areas in tropical regions.	Intertidal and supratidal zones, semi-diurnal to diurnal, flooding by brackish or saltwater.	Mangrove, halophytic shrub, halophytic (succulent) forb, graminoids.	Mangrove swamps
Aquatic Vegetation (5.A, 5.B)	Aquatic wetlands are shallow waters dominated by rooted, submerged and floating aquatic plants. They are associated with permanent still or slow-moving waters, such as shallow potholes, ponds, rivers and lakes or in oceans. Aquatic plants may occur in mineral or in well-humified sedimentary peat.	+/- Permanent deep flooding (0.5-2 m), or deep water lakes and oceans.	Hydromorphic (aquatic) herb, emergents <10% cover.