Wetland Terms

(Riparian and Wetland Research Program)

Abandoned Meander Channel. A former stream channel that was cut off from the rest of the river and typically lacks yearlong standing water.

Aerobic. Condition in which molecular oxygen is present in the environment.

Albic Soil Horizon. A mineral soil horizon of virtually clean sand and silt particles; clays and free iron oxides have been removed most commonly by leaching, leaving the soil horizon a whitish appearance.

Alfisols. A soil order composed of soils having significantly more clay in the B horizon than in the A horizon and high base status.

Alkaline. Water or soil with a pH greater than 7.4.

Alluvial Soil. Sediments (clay, silt, sand, gravel, cobbles, and boulders) deposited by running water, ordinarily occurring on floodplains and at the base of ridges and slopes.

Alluvial Terrace. Deposits of alluvial soil that mark former floodplains. Typically, a floodplain may have several sets of alluvial terraces at different elevations and of different ages (the higher the elevation, the older the age).

Alluvium. An accumulation of sediments deposited by streams or rivers.

Anaerobic. Condition in which molecular oxygen is absent from the environment. This commonly occurs in wetlands where soils experience prolonged saturation by water.

Andisols. Dark mineral soils developed in volcanic ash, pumice, cinders, other volcanic ejecta, or volcaniclastic materials.

Aqualfs. Soils with aquic conditions and having clay accumulating in the B horizon: wet Alfisols.

Aquatic Bed (Cowardin and others 1979). A class of wetland and deepwater habitat dominated by plants that grow principally on or below the surface of the water for most of the growing season in most years.

Aquents. Soils with aquic conditions and lacking distinct soil horizons in the subsoil: wet Entisols.

Aquepts. Soils with aquic conditions and showing little soil development in the B horizon: wet Inceptisols.

Aquic Conditions. These soils experience continuous or periodic saturation and reduction. The presence of these conditions is indicated by redoximorphic features.

Aquic Moisture Regime (obsolete). A moisture condition associated with a seasonal reducing environment that is virtually free of dissolved oxygen because the soil is saturated by ground water or by water of the capillary fringe, as in soils in Aquic suborders and Aquic subgroups.

Argillic Soil Horizon. A soil horizon that shows evidence of movement or accumulation of silicate clays, and possesses a higher clay content than an overlying horizon.

Available Water Capacity. The ability of a soil to hold water in a form available to plants, expressed in inches of water per inch of soil depth. Classes are:

  • Low = 0 - 0.12
  • Moderate = 0.13 - 0.17
  • High = >0.17

Average Canopy Cover. Refers to the "average" canopy cover of a particular species for the stands that it was recorded. For example, the number of stands sampled for a habitat type or community type may be 20. However, a particular species may only occur in 7 of the 20 stands. The average canopy cover therefore represents the "average" canopy cover of that particular species in the 7 stands.

Backwater Area. Seasonal or permanent water bodies found in the lowest parts of floodplains, typically circular or oval in shape.

Bars (Alluvial). Sediment accumulations along waterways deposited by moving water. Examples include:

  • Point bars -- bars that are formed on the inside of a meander channel
  • Side bars -- bars that are formed along the edges of relatively straight sections of a river
  • Mid-channel bars -- these are found within the channel and generally become more noticeable during low flow periods
  • Delta bars -- bars formed immediately downstream of the confluences of a tributary and the main river

Beaver Dams. Dams built by beavers that span the stream channel. In general, water is still flowing through the riparian system.

Bog (Mitsch and Gosselink 1986). A sphagnum moss-dominated community whose only water source is rainwater. They are extremely low in nutrients, form acidic peats, and are a northern phenomenon generally associated with low temperatures and short growing seasons.

Browse. Shrubby and woody forage consumed by wildlife.

Calcic Soil Horizon. A subsurface soil horizon with an accumulation of carbonates.

Cambic Soil Horizon. An altered soil horizon that does not have the dark color, organic matter content, or structure of a histic, mollic, or umbric epipedon. Cambic horizons possess the following characteristics:

  • texture is very fine sand, loamy very fine sand, or finer,
  • soil structure or absence of rock structure in at least 1/2 of the horizon (by volume), and
  • the alteration of soil color by the loss of carbonates or aquic conditions.

Canopy Coverage. The percentage of ground covered by the gross outline of an individual plant's foliage; or collectively covered by all individuals of a species within a stand or a sample plot.

Capillary Fringe. A zone immediately above the water table in which water is drawn upward from the water table by capillary action.

Carr. Wetland on organic soil with greater than 25% cover of shrubs. Typically, carrs are dominated by willows (Salix species).

Climax Community. Refers to the final or steady state plant community which is self-perpetuating and in dynamic equilibrium with its environment.

Colluvium. A deposit of unconsolidated geologic materials and soil accumulated at the base of slopes as a result of gravity.

Community (Plant Community). An assembly of plants living together, reflecting no particular ecological status.

Community Type. An aggregation of all plant communities distinguished by floristic and structural similarities in both overstory and undergrowth layers. A unit of vegetation within a classification.

Constancy. The percentage of sampled stands in which a species occurs.

Disclimax. Where recurring disturbances, such as grazing (e.g., zootic disclimax) or periodic burning (e.g., fire disclimax) exert the predominant influence in maintaining the structure and composition of the steady-state vegetation. Disclimaxes, such as the zootic climax or fire climax, are not the basis for recognizing habitat types.

Diversity. The kind and amount of species in a community per unit area.

Drained. A condition in which ground or surface water has been removed by artificial means.

Dominance Type (Equivalent to Cover Type). An aggregation of all stands (individual plant communities), grouped and named simply by the species with the greatest canopy coverage in the overstory or upper layer. In this classification, canopy cover of dominant species is greater than 25 %.

Emergent Plant. A rooted herbaceous plant species that has parts extending above a water surface.

Emergent Wetland (Cowardin and others 1979). A class of wetland habitat characterized by erect, rooted, herbaceous hydrophytes, excluding mosses and lichens.

Entisols. A soil order including soils of slight or recent development; common along rivers and floodplains.

Ephermeral Stream. A stream or stretch of a stream that flows only in direct response to precipitation. It receives no water from springs and no long-continued supply from melting snow or other surface source. Its stream channel is at all times above the water table. These streams do not normally flow for 30 consecutive days.

Epipedon. Diagnostic soil horizons formed at the soil surface (e.g., argillic horizon).

Facultative Species. Plant species that can occur both in wetlands and uplands. There are three subcategories of facultative species:

  1. Facultative wetland plants,
  2. Facultative plants, and
  3. Facultative upland plants.

Facultative Plants (FAC). A plant species that is equally likely to occur in wetlands or nonwetlands (estimated probability 34-66%).

Facultative Upland Plants (FACU). A plant species that usually occurs in nonwetlands (estimated probability 67 - 99%), but occasionally is found in wetlands (estimated probability 1 - 33%).

Facultative Wetland Plants (FACW). A plant species that usually occurs in wetlands (estimated probability 67 - 99%), but occasionally is found in nonwetlands.

Fen (Mitsch and Gosselink 1986). A non-acidic peat-forming wetland that receives nutrients from sources other than precipitation, usually through groundwater movement.

Fibric Materials. Plant materials that show very little signs of decomposition. Plant fiber content before rubbing between fingers is at least 3/4 of the soil volume.

Fibrists. Organic soils (peats) in which plant remains show very little decomposition and retain original shape; more than 2/3 of the fibers remain after rubbing the materials between the fingers.

Flooded. A condition in which the soil surface is temporarily covered with flowing water from any source, such as streams overflowing their banks and runoff from adjacent or surrounding slopes, or any combination of sources.

Floodplain. An alluvial plain caused by the overbank deposition of alluvial material. Typically appearing as flat expanses of land bordering a stream or river. Most floodplains are accompanied by a series of alluvial terraces of varying levels.

Fluvial. Pertaining to or produced by the action of moving water.

Forb. A herbaceous plant, usually broadleaved, that is not a graminoid.

Forested Wetland (Cowardin and others 1979). A class of wetland habitat characterized by woody vegetation that is 6m (20 ft) tall or taller.

Forested Wetlands. Occur near springs and seeps and in areas with naturally high water tables, such as river floodplains. Two general types of forested wetlands occur in Montana:

  1. Those dominated by coniferous tree species, and
  2. Those dominated by deciduous angiosperm tree species.

Frequently Flooded. A class of flood frequency in which flooding is common during most years (more than a 50% chance of flooding in any year, or more than 50 times in 100 years).

Gallery Forest. A strip of forest confined to a stream margin or floodplain in an otherwise unforested landscape.

Gleization. A process in staurated or nearly saturated soils which involves the reduction of iron. This process tends to give gray colors (low chroma) to those parts of the soil from which the iron has been reduced or removed and rust colors (high chroma) to those where the iron has oxidized and accumulated.

Gleyed Soil (obsolete). A soil condition resulting from prolonged soil saturation, which is manifested by the presence of bluish or greenish colors through the soil mass or in mottles (spots or streaks) among other colors. Gleying occurs unde reducing soil conditions resulting from soil saturation, by which iron is reduced predominantly to the ferrous state. See also redox depletions.

Graminoid. Grass or grass-like plant, such as species of the Poaceae (grasses), Cyperaceae (sedges) and Juncaceae (rushes).

Ground Water. Water occupying the interconnected pore spaces in the soil or geologic material below the water table, this water has a positive pressure.

Growing Season. The portion of the year when soil temperatures are above biologic zero (4F) as defined by Soil Taxonomy; the following growing season months are assumed for each of the soil temperature regimes:

  • Thermic (February - October)
  • Mesic (March - October)
  • Frigid (May - September)
  • Cryic (June - August)
  • Pergelic (July - August)

Habitat Type. The land areas that supports, or has the potential of supporting, the same primary climax vegetation. A habitat type classification is a vegetation based ecological site classification. It is based on the potential of the site to produce a specific plant community (plant association). It has been used to classify grasslands, shrublands, woodlands, and forests throughout the western United States.

Herbaceous. Nonwoody vegetation, such as graminoids and forbs.

Histic Epipedon. A 20 to 40 cm (8 to 16 in) soil layer at or near the surface that is saturated for 30 consecutive days or more during the growing season in most years and contains a minimum of 20% organic matter when no clay is present or a minimum of 30% of organic matter when 60% or more clay is present. Generally, a thin horizon of peat or muck is present if the soil has not been plowed.

Histosols. A soil order composed of organic soils (peats and mucks) with generally greater than 50% organic matter in the upper 80 cm (32 in) or that are of any thickness if overlying rock.

Horizon. A distinct layer of soil, more or less parallel with soil surface, having similar properties such as color, texture, and permeability; the soil profiles is subdivided into the following major horizons:

  • A horizon -- A surface horizon characterized by an accumulation of organic material,
  • E horizon -- Most commonly a surface horizon, characterized by leaching of organic matter, iron, and clay
  • B horizon -- A subsurface horizon characterized by relative accumulation of organic matter, iron, clay, or aluminum
  • C horizon -- Undisturbed, unaltered parent material

Hydric Soil (USDA SCS 1990). A soil that is saturated, flooded, or ponded long enough during the growing season to develop anaerobic conditions in the upper part of the soil profile. Hydric soil indicators are Histosol, histic epipedon, sulfidic odor, aquic moisture regime, reducing conditions, gleyed or low-chroma colors, concretions, high organic content in surface layer in sandy soils, organic streaking in sandy soils, listed on local Hydric Soils List, and listed on National Hydric Soils List (Environmental Laboratory, 1987).

Hydrology. The science dealing with the properties, distribution, and circulation of water.

Hydrophyte. Any macrophytic plant that grows in water or on a substrate that is at least potentially deficient in oxygen as a result of excessive water content; plants typically found in wetland and other aquatic habitats.

Hydrophytic Vegetation. Plant life growing in water or on a substrate that is at least potentially deficient in oxygen as a result of excessive water content.

Inceptisols. A soil order composed of soils of intermediate development; morphological characteristics are generally too weak to meet requirements of other soil orders.

Incidental Type. Refers to a habitat type or community type that rarely occurs or occupies only a small area of a wetland zone.

Intermittent Stream. A stream or reach of stream which flows only at certain times of the year when it receives water from springs or from some surface source (e.g., melting snow). They are usually divided with respect to the source of their water into spring-fed or surface-fed intermittent streams. These streams generally flow continuously during periods of at least one month or more during the year.

Inundation. A condition in which water temporarily or permanently covers a land surface.

Irrigation Canal. Includes all types of canals associated with irrigation systems.

Lacustrine System (Cowardin and others 1979). Any wetland or deepwater habitat with the following characteristics:

  • Situated in a topographic depression or dammed river channel,
  • Lacking trees, shrubs, persistent emergents, emergent mosses or lichens with greater than 30% areal coverage, and
  • Total area exceed 8 ha (20 acres).

Lake. A natural topographic depression collecting a body of water covering at least 8 ha (20 acres) with surface water.

Lentic Wetland. See still water wetland.

Long Duration (Flooding). A duration class in which inundation for a single event ranges from 7 days to 1 month.

Lotic Wetland. See riparian wetland.

Major Type. Refers to a habitat type or community type that occupies an extensive area within a wetland zone.

Marsh. A frequently or continually inundated wetland, often developing in shallow ponds, depressions, and river margins. Marshes are dominated by herbaceous plants, such as grasses (e.g., Phragmites), sedges, cattails (e.g., Typha), and bulrushes (e.g., Scirpus). Waters are usually neutral to basic.

Mineral Soil. Soils composed of predominantly mineral materials (sands, silts, and clays) instead of organic materials. The soil contains less than 20% organic matter.

Minor Type. Refers to a habitat type or community type that seldom occupies large areas but may be common within a wetland zone.

Mollic Epipedon. A surface layer that consists of mineral soil materials and have the following properties:

  • Soil structure that is not both massive and hard or very hard when dry,
  • Munsell color value less than 3 moist and 5 dry, and chroma less than 3,
  • Base saturation of at least 50%,
  • At least 1% organic matter throughout the horizon,
  • Typically moist for at least 3 months in most years, and
  • At least 18 cm (7 in) thick.

Mollisols. A solid order including soils with a thick dark brown to black surface horizon (mollic epipedon), has a high base saturation, and a well-developed structure. Typically associated with grassland soils.

Monotypic Stands. Stands composed primarily of a single species.

Montane. That region between the subalpine zone and the grassland zone or more broadly, mountain slopes below the alpine zone.

Mottling (obsolete). Spots or blotches of different color or shades of color interspersed with the dominant color in a soil layer, usually resulting from the presence of periodic reducing soil conditions. See also redox concentrations.

Natric Horizon. A special kind of argillic horizon. Natric horizons have all the properties of argillic horizons but, in addition, are 15% or more sodium saturated. Their formation is favored where leaching results in the accumulation of sodium on the cation-exchanger complex.

Nonhydric Soils. A soil that has developed under predominantly unsaturated soil conditions.

Nonpersistent Vegetation. Plants that break down readily after the growing season; no evidence of previous year's growth at the beginning of the next growing season.

Nonwetland. Any area that has sufficiently dry conditions that hydrophytic vegetation, hydric soils, and/or wetland hydrology are lacking; it includes upland as well as former wetlands that are effectively drained.

Obligate Wetland Plant. Refers to a plant species that occurs almost always (estimated probability greater than 99 percent) under natural conditions in wetlands.

Organic Soil. Soils composed of primarily organic rather than mineral material. Equivalent to histosols and includes peats and mucks.

Overbank Flooding. Any situation in which inundation occurs as a result of the water level of a river or stream rising above bank level.

Overflow Channel. An abandoned channel in a floodplain tham may carry water during periods of high stream or river flows.

Oxbow Lake. A meander channel of a stream or river that is formed by breaching of a meander loop during flood stage. The ends of the cut-off meander are blocked by bank sediments.

Palustrine System (Cowardin and others 1979). Any nontidal wetland of a class dominated by trees, shrubs, persistent emergents, or emergent mosses or lichens.

Parent Material. The unconsolidated and undeveloped mineral or organic matter from which the solum (soil) is developed.

Peraquic Moisture Regime. A soil condition in which reducing conditions always occur due to the presence of ground water at or near the soil surface.

Perennial Stream. A stream or reach of a stream that flows continuously. They are generally fed in part by springs. Surface water elevations are commonly lower than water table elevations in adjacent soils.

Permanently Flooded. A water regime condition where standing water covers the land surface throughout the year (but may be absent during extreme droughts).

Permeability. The quality of the soil that enables water to move downward through the profile, measured as the number of cm (in) per hour that water moves downward through the saturated soil.

Phase. A subdivision of a habitat type or representing a characteristic variation in climax vegetation and environmental conditions.

Pioneer Species. Species that colonize bare areas (e.g., gravel bars) where there is little or no competition from other species.

Plant Association. Used to group together all those stands of climax vegetation which occur in environments so similar that there is much floristic similarity throughout all layers of the vegetation.

Playa. A periodically flooded wetland basin. Playas are common in parts of southwest Montana.

Pond. Bodies of water encircled by wetland vegetation. Wave action is minimal, allowing emergent vegetation to establish.

Ponded. A condition in which free water covers the soil surface, for example, in a closed depression. The water is removed only by percolation, evaporated, or transpiration.

Pooled Channel Stream. An intermittent stream with significant surface pool area and without flowing surface water. The water sources for the pools are springs within the channel.

Poorly Drained. Water is removed from the soil so slowly that the soil is saturated periodically during the growing season or remains wet for long periods (greater than 7 days).

Pothole. A depressional wetland community caused by glaciation and is common to portions of the Northern Great Plains. The body of water is less than 8 ha (20 acres) in size.

Primary Succession. Occurs on a bare surface not previously occupied by plants, such as a recently deposited alluvial bar.

Range of Canopy Cover. Refers to the "range" (e.g., low and high values) of canopy cover of a particular species for all the stands sampled for a habitat type or community type.

Redox Concentrations. A redoximorphic feature characterized by zones in the soil of apparent accumulation of iron and manganese oxides. These may form as nodules, concretions, soft bodies, or pore linings and vary in shape, size, and color.

Redox Depletions. A redoximorphic feature characterized by zones in the soil of low chroma (less than 3) where iron and manganese oxides alone have been removed, or where both iron/manganese oxides and clay have been removed.

Redoximorphic Features. Soil features associated with wetness and are formed as a result of the reduction and oxidation of iron and manganese compounds in the soil following saturation with water (See redox concentrations and redox depletions.)

Reduced Matrix. A redoximorphic feature characterized by a soil matrix having low chroma (less than 3) in situ, but increases in hue or chroma when exposed (within 30 minutes) to air.

Reservoir. An artificial (dammed) water body with at least 8 ha (20 acres) covered by surface water.

Riparian. adj. Of, on, or relating to the banks of a natural course of water (Latin riparius, from ripa, bank).

Riparian Plant Association. A plant community representing the latest successional stage attainable on a specific, hydrologically influenced surface (equivalent potential natural community type).

Riparian Wetlands (Lotic Wetlands). Riparian wetlands are wetlands associated with running water systems found along rivers, streams, and drainageways. Such wetlands contain a defined channel and floodplain. The channel is an open conduit which periodically, or continuously, carries flowing water, dissolved and suspended material. Beaver ponds, seeps, springs, and wet meadows on the floodplain of, or assiciated with, a river or stream are part of the riparian wetland.

Riparian or Wetland Ecosystem. The ecosystem located between aquatic and terrestrial environments. Identified by hydric soil characteristics and riparian or wetland plant species that requires or tolerates free water conditoins of varying duration.

Riparian or Wetland Species. Plant species occurring within the riparian or wetland zone. Obligate riparian or wetland species require the environmental conditions associated with the riparian or wetland zone. Facultative riparian or wetland species are tolerant of these environmental conditions, but also occur in uplands.

Riparian Zone. A geographically delineated portion of the riparian ecosystem based on management concerns.

River. Rivers are usually larger than streams. They flow year round, in years of normal precipitation, and whe significant amounts of water are not being diverted out of them.

Riverbank. That portion of the channel bank cross-section that controls the lateral movement of water.

Riverine System (Cowardin and others 1979). Any wetland or deepwater habitat contained within a channel, with exception of wetlands dominated by trees, shrubs, persistent emergents, emergent mosses, or lichens.

Salic Horizon. A mineral soil horizon 15 cm (6 in) or more thick enriched with secondary soluble salts.

Saline. Soil or water containing sufficient soluble salts to interfere with the growth of most plants.

Saturated. A soil condition in which all voids (pore spaces) between soil particles are filled with water.

Secondary Succession. The process of changing biotic communities that occurs following disturbances to a site that has previously been occupied by living organisms.

Seep. Groundwater discharge areas. In general, seeps have less flow than a spring.

Seral. Refers to vegetation that has not theoretically attained a steady state with its environment, and current populations of some species are being replaced by other species; a community or species that is replaced by another community or species as succession progresses.

Series. Refers to a group of habitat types having the same climax species.

Scrub-Shrub Wetland (Cowardin and others 1979). A class of wetland habitat which includes areas dominated by woody vegetation less than 6m (20 ft) tall. It may include true shrubs, young trees, or trees or shrubs that are small or stunted becuase of environmental conditions.

Shrub. A multi-stemmed woody plant generally shorter than 4.8 m (16 ft).

Small Mountain Lake. A natural topographic depression collection a body of water covering less than 8 ha (20 acres) with surface water.

Soil Series. A subdivision of a soil family that consists of soils that are similar in all major soil profile characteristics and arrangements.

Solum. The upper and most weathered part of the soil profile; the A and B horizons.

Somewhat Poorly Drained. Water is removed slowly enough that the soil is wet for significant periods during the growing season.Spring. Groundwater discharge areas. In general, springs are considered to have more flow than seeps.

Stable Community. The condition of little or no perceived change in plant communities that are in relative equilibrium with existing environmental conditions. It describes persistent but not necessarily climax stages in plant succession.

Stand. A plant community that is relatively uniform in composition, structure, and habitat conditions; a sample unit.

Stream. A natural waterway that is defined as first to third order.

Streambank. That portion of the channel bank cross-section that controls the lateral movement of water.

Stream Order. A classification of streams according to the number of tributaries. Order 1 streams have no tributaries; a stream of Order 2 or higher has 2 or more tributaries of the next lower order.

Still Water Wetlands (Lentic Wetlands). These wetlands occur in basins and lack a defined channel and floodplain. Included are permanent (e.g., perennial) or intermittent bodies of water such as lakes, reservoirs, potholes, marshes, ponds, and stockponds. Other examples include fens, bogs, wet meadows, and seeps not associated with a defined channel.

Stockpond. An artificial (dammed) body of water of less than 8 ha (20 ft) covered by surface water.

Subterranean Stream. A stream that flows underground for part of the stream reach.

Succession. The change or sequence of plant, animal, and microbial communities that successively occupy an area over a period of time.

  • Primary succession begins on a bare surface not previously occupied by living organisms, such as a recently deposited gravel bar.
  • Secondary succession occurs following disturbances on sites that previously supported living organisms.

Swale. A depression or topographical low area.

Sward. An expanse of grass or grass-like plants.

Tree. A single-stemmed woody plant generally taller than 4.8 m (16 ft).

Unconsolidated Bottom (Cowardin and others 1979). A class of wetland or deepwater habitat with at least 25% cover of particles smaller than stones, and with a vegetative cover less than 30%.

Unconsolidated Shore (Cowardin and others 1979). A class of wetland habitat having three characteristics:

  • Unconsolidated substrates with less than 75% areal cover of stones, boulders, or bedrock,
  • Less than 30% areal cover of vegetation other than pioneering plants, and
  • any of the following water regimes: irregularly exposed, regularly flooded, seasonally flooded, irregularly flooded, temporarily flooded, intermittently flooded, saturated, or artifically flooded.

Uplands. Any area that does not qualify as a wetland because the associated hydrologic regime is not sufficiently wet to elicit development of vegetation, soils, and/or hydrologic characteristics associated with wetlands. Such areas occurring in floodplains are more appropriately termed nonwetlands.

Very Long Duration (Flooding). A duration class in which inundation for a single event is greater than 1 month.

Very Poorly Drained. Water is removed from the soil so slowly that free water remains at or on the surface during most of the growing season.

Water Mark. A line on vegetation or other upright structures that represents the maximum height reached during a flood, ponding, or inundation event.

Water Regime (Nontidal) (Cowardin and others 1979). Includes the following types:

  • Permanently flooded -- water covers the land surface throughout the year in all years. Vegetation is composed of obligate hydrophytes.
  • Intermittently exposed -- surface water is present throughout the year except in years of extreme drought
  • Semipermanently flooded -- surface water persists throughout the growing season in most years. When surface water is absent, the water table is usually at or very near the land surface.
  • Seasonally flooded -- surface water is present for extended period expecially early in the growing season, but is absent by the end of the season in most years. When surface water is absent, the water table is often near the soil surface.
  • Saturated -- the substrate is saturated to the surface for extended periods during the growing season, but surface water is seldom present.
  • Temporarily flooded -- surface water is present for brief periods during the growing season, but the water table usually lies well below the soil surface for most of the season. Plants that grow both in uplands and wetlands are characteristic of the temporarily flooded regime.
  • Intermittently flooded -- the substrate is usually exposed, but surface water is present for variable periods without detectable seasonal periodicity. Weeks, months, or even years may intervene between periods of inundation. The dominant plant communities under this regime may change as soil moisture conditions change. Some areas exhibiting this regime may not fall within the wetland definition because they do not have hydric soils or support hydrophytic plants.

Water Table. The upper surface of the zone of saturation within the soil or geologic material.

Wet Meadow. A herbaceous wetland on mineral soil. Generally, wet meadows occur in seasonally flooded basins and flats. Soils are usually dry for part of the growing season.

Wetlands. Areas that under normal circumstances have hydrophytic vegetation, hydric soils, and wetland hydrology. It includes landscape unit such as bogs, fens, carrs, marshes, and lowlands covered with shallow, and sometimes ephemeral or intermittent waters. Wetlands are also potholes, sloughs, wet meadows, riparian zones, overflow areas, and shallow lakes and ponds having submerged and emergent vegetation. permanent waters of streams and water deeper than 3 m (approx. 10 ft) in lakes and reservoirs are not considered wetlands.

Wetland Hydrology. Permanent or periodic inundation or prolonged soil saturation sufficient to creat anaerobic conditions in the soil. Primary wetland hydrology indicators are: inundated, saturated in upper 4.7 cm (12 in), water marks, drift lines, sediment deposits, drainage patterns in wetlands. Secondary wetland hydrology indicators are: oxidized root channels in upper 4.7 cm (12 in), water-stained leaves, local soil survey data, FAC-neutral test (Environmental Laboratory, 1987).

Wetland Status. Refers to plant species that have exhibited an ability to develop to maturity and reproduce in an environment where all or portions of the soil within the root zone become, periodically or continuously, saturated or inundated during the growing season. The ability to grow and reproduce in wetlands is due to morphological and/or physiological adaptations and/or reproductive strategies of the plant (Reed 1988a; 1988b). Categories are as follows:

  • OBL (Obligate Wetland). Refers to species that almost always occur (estimated probability greater than 99%) under natural conditions in wetlands.
  • FACW (Facultative Wetland). Refers to species that usually occur in wetlands (estimated probability is 67 - 99%), but is occasionally found in nonwetlands.
  • FAC (Facultative). Refers to species that are equally likely to occur in wetlands or nonwetlands (estimated probability is 34 - 66%).
  • FACU (Facultative Upland). Refers to species that usually occur in nonwetlands (estimated probability is 67 - 99%), but are occasionally found in wetlands (estimated probability is 1 - 33%).