WETLAND is a kind of ecosystem in which, due to saturation by water, anaerobiosis of the upper soil/sediment/ sedentate (especially the rhizosphere) has selected for biota tolerant of that condition and has promoted development of hydric soil characteristics, and in which water levels are usually within 2 m of the sediment surface, especially during periods of plant growth.

"Those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas."

Federal Manual for Identifying and Delineating Jurisdictional Wetlands (1989) US-EPA, 40 CFR 230.3 and CE, 33 CFR 328.3.

1) vegetation (of the kind and/or amount) that may or may not be peat-producing,

2) animals as the dominant biota, and

3) sediment/sedentate that may be organic or mineral.

1) "Mire"

2) "Wetland-Not-Mire" [no term yet identified]

The distinction between these types is not always clear.

"MIRE" is a kind of wetland in which the current vegetation and surface waters are isolated from underlying mineral sediments by a sufficiently thick layer of organic soils and whose current natural vegetation and surface conditions promote the accumulation of a kind of organic sediment/sedentate called peat.

[I know of no mire that is characterized primarily by animals.]

1) there is an inadequate layer of organic sediment/ sedentate to isolate current vegetation and surface waters from underlying mineral sediments and/or

2) current natural vegetation and surface conditions do not promote the production and/or preservation of an organic sediment/sedentate.

(i.e., all those kinds of wetland that are NOT mire)

1. peat-producing vegetation and peat-preserving conditions exist, but the current vegetation and surface waters are not isolated from the underlying mineral sediment, because the

a) site is (too) young, [This kind may become a mire in time.]

b) peat sediment/sedentate was once thicker, but has thinned as a result of drainage and exposure to decomposing forces. [This type may have been, but is no longer a mire.]

or because the

2. peat-producing vegetation and/or peat-preserving conditions have not existed and do not now exist at this site, so the current vegetation and surface waters are not isolated from the underlying mineral sediment. [This kind of wetland has not been a mire and will not be a mire if this vegetation and these conditions persist.]

"PEATLAND" refers to a geographic area where the surface sediments/sedentates are predominantly organic and are called peat. Because the presence of peat-forming vegetation is not required, "peatland" is not a kind of "wetland" (and "wetland" is not a kind of "peatland").

"Wet lands" and "peat lands" are terms that are also distinct from "wetland".

Types of wetlands may be distinguished by

1. Vegetation -

physiognomy of the dominant vegetation (e.g., forest)

dominant plant community (e.g., Caricetum lasiocarpae),

dominant species (e.g., Carex lasiocarpa),

species diversity/richness (e.g., monospecific);

• or by

2. Sets of Current Abiotic Factors -

sediment/sedentate types (e.g., sedge peat),

sources of water (e.g., minerogenous),

surface topography (e.g., sloped),

nature of water movement (e.g., slow, subsurface),

pH classes (e.g., acid),

available nutrients (e.g., oligotrophic);

or by

3. Other factors (e.g., origin and genesis); or

4. Combinations of the above factors.

Sediments

Sediment/sedentate may be of:

• unknown type,
• both organic and mineral matter,
• only organic matter,
• kinds and characteristics of peat (e.g., sedge peat, well decomposed)
• only mineral matter,
• kinds and characteristics.

Current Source of Surface Water

Current surface and near-surface water may be

• only direct precipitation,
• mostly surface runoff from mineral terrain,
• mostly seepage (ground water) from mineral terrain,
• mostly artesian/spring water,
• mostly from a rising water table,
• condensation.

Current Surface Water Movement

Flow of surface and near-surface water may be

• negligible, no consistent direction;
• slow, unidirectional,
• horizontal, as sheet-flow, above surface;
• horizontal, as channel-flow, above surface;
• horizontal, below surface;
• vertical downward;
• rapid, horizontal as
• sheet flow, or
• channelized flow;
• varied in rate and direction (flooding, tides, wind).

Current Plant Physiognomy

The dominant vegetation may be:

• alga,
• lichen,
• liverwort,
• moss,
• graminoid,
• forb,
• shrub, or
• tree.

Current Surface Topography

The current sediment surface may be:

• concave,
• flat,
• level,
• sloped,
• stepped;

Current Sediment Surface Topography

convex:

• domed symmetrically (= concentric),
• domed assymmetrically (= eccentric),
• domed, flat-topped,
• ridged.

Position in the Landscape

Wetlands may occur as:

• watershed blanket wetlands,
• slope wetlands,
• valley wetlands,
• kettle-hole wetlands,
• flood-plain wetlands,
• estuarine wetlands,
• wetlands adjacent to lakes or oceans.