Cowardin Classification System
The Cowardin Classification System is based on five systems:
Riverine, Lacustrine, Palustrine, Marine, and Estuarine (the latter two are associated with saltwater and/or coastal waterbodies, and as such are not applicable in Alberta). These are further divided into subsystems based on the degree or frequency of inundation, and then into classes based on hydrological, substrate, and/or vegetation characteristics. All of these systems except for palustrine can include both wetland and deepwater habitats.
Riverine systems include all wetlands and deepwater habitats contained within a channel, except for wetlands dominated by vegetation made up of trees, shrubs, persistent emergents, emergent mosses, or lichens (which will generally fall within the palustrine system), or habitats with ocean-derived brackish water (exceeding 0.05% salts, which will generally fall within the Estuarine system). Riverine systems usually contain flowing water, and are generally bounded by upland areas to the lateral edges of the channel, and by lacustrine or estuarine systems downstream where they drain into a stationary waterbody.
Riverine systems can be divided into four subsystems:
- Tidal subsystems, in which water level and velocity varies under tidal influences, though always with salinities less than 0.05%
- Lower Perennial subsystems, in which low gradients result in low water velocity and a well-developed floodplain, usually with a muddy, sandy, or silty substrate.
- Upper Perennial subsystems, in which higher gradients result in high water velocity, with limited floodplain development and a substrate of primarily gravel and cobbles.
- Intermittent subsystems, in which water flows only for part of the year, and forming either isolated pools or drying up completely throughout the rest of the year.
These subsystems may be further broken down into classes based on substrate type or vegetation, including rock bottom, unconsolidated bottom, aquatic bed, streambed, rocky shore, unconsolidated shore, and nonpersistent emergent wetland.
Lacustrine systems include all wetland and deepwater habitats associated with depressions or damned channels greater than 8 ha in area, and which have less than 30% of their area dominated by trees, shrubs, or emergent vegetation. Smaller waterbodies may also be included in this category if they exceed 2 m in depth, or if they have exposed or wave-formed shorelines.
Lacustrine systems can be divided into two subsystems:
- Littoral subsystems, which extend from the shore outwards to a depth of 2 m or to the limits of non-persistent emergent vegetation.
- Limnetic subsystems, which comprise all of the deepwater habitats beyond the limits of the littoral zone. Many smaller lacustrine systems may lack the limnetic subsystem.
These subsystems may be further broken down into classes based on substrate type or vegetation, including rock bottom, unconsolidated bottom, aquatic bed, rocky shore, unconsolidated shore, and nonpersistent emergent wetland.
Palustrine systems include all nontidal wetlands dominated by trees, shrubs, persistent emergents, emergent mosses or lichens, and any such areas within tidal systems where ocean-derived salinities are less than 0.05%. This system encompasses most wetlands referred to as marshes, swamps, bogs, fens, and wet prairies under other classification systems. They are often found within or adjacent to riverine and lacustrine systems, though they may be isolated in the landscape as in the case of marshes and ponds in the prairie region.
Palustrine systems are the only system under Cowardin that are not divided into subsystems; however, they are still divided into classes, depending on vegetation, sediment type, and hydrological regime:
- Rock bottom
- Unconsolidated bottom
- Aquatic bed
- Unconsolidated shore
- Moss-lichen wetland
- Emergent wetland
- Scrub-shrub wetland
- Forested wetland
Marine systems include the open ocean habitats from edge of the continental shelf shorewards, including any areas under the direct influence of wave action. They are divided into subtidal and intertidal subsystems, which differ in whether they are continuously or only intermittently submerged by tides. Alberta does not have any marine systems.
Estuarine systems consist of deepwater tidal habitats and associated tidal wetlands, with at least sporadic access to the ocean and water consisting of a mixture of riverine and ocean waters. As with marine systems, they are divided into subtidal and intertidal subsystems, which are distinguished in the same way. Alberta does not have any estuarine systems.