wetlands

Clean water act wetland definition

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

Wetland definition

1. hydrology

2. veg

3. soils

Any ecosystem that has saturated soils for a portion of the year, creates hydric soils, and supports hydrophytes

why do we classify wetlands?

to have a base/general understanding of a wetland, the similarities and differences of each ecosystem and how it may work

where are wetlands

everywhere

United States Classification System definition

Wetlands are lands transitional between terrestrial and aquatic systems where the

water table is usually at or near the surface or the land is covered by shallow water...

Wetlands must have one or more of the following three attributes: (1) at least periodically, the

land supports predominantly hydrophytes; (2) the substrate is predominantly undrained hydric

soil; and (3) the substrate is non-soil and is saturated with water or covered by shallow water at

some time during the growing season of each year

USFW did what in 1974

US fish and wildlife service began a rigorous wetland inventory

USFW classification system

hierarchal approach, similar to plant taxonomy

1. system

2. subsystem

3. class

4. subclass

5. dominance type

6. modifiers

System

“complex of wetlands sharing similar hydrologic, geomorphic, chemical, or biological factors”

Systems and subsystems

• based primarily on geologic and hydrologic factors

• broad vegetation types addressed in the Classes category

Marine

Open ocean overlying the continental shelf and its associated high-energy coastline - generally >30 ppt salinity

Subsystems:

Subtidal: Substrate continuously submerged

Intertidal: Substrate exposed and flooded by tides, including the splash zone

Estuarine

Deepwater tidal habitats and adjacent tidal wetlands

• usually semi-enclosed but have...

• open, partially obstructed, or sporadic access to the ocean and...

• ocean water is occasionally diluted by freshwater

Subsystems:

Subtidal: Substrate continuously submerged

Intertidal: Substrate exposed and flooded by tides, including the splash zone

Riverine

Includes all wetlands and deep-water habitats contained

within a channel, EXCEPT:

1. Wetlands dominated by trees, shrubs, persistent emergent, emergent mosses, or lichens

2. Deepwater habitats with water containing ocean derived salts in excess of 0.5‰

Riverine

Subsystems:

Tidal - gradient is low & water velocity fluctuates under tidal influence (floodplain well developed)

Lower perennial - gradient is low & water velocity is slow - sand & mud (floodplain well developed)

Upper perennial - gradient is high & water velocity is fast - rocks, cobbles, gravel with occasional sand (very little floodplain development)

Intermittent - water flow intermittently & may remain in isolated pools

Lacustrine

Includes wetlands & deep-water habitats with all the following characteristics:

a) Topographic depression or dammed river channel

b) Less than 30% coverage of plants

c) Total area exceeds 8 ha (20 ac)

Lacustrine

Subsystems:

Limnetic: all deepwater habitats > 2 m

Littoral: wetlands from shoreline to a depth of 2 m below water or to the maximum extent of non- persistent emergent plants

Palustrine

Includes all non-tidal wetlands dominated by trees, shrubs, persistent emergents, emergent mosses or lichens and wetlands in tidal areas where salinity is below 0.5%.

It also includes wetlands lacking such vegetation, but with all the following characteristics:

a) area < 8 ha (20 ac)

b) Lack of active wave-formed or bedrock shoreline features

c) water depth in the deepest part of basin less than 2 m at low water

Palustrine includes:

no subsystems

• swamps 

• bogs

• permanent or intermittent

Class

Describes general appearance of the habitat in terms of either the dominant life form of the vegetation or substrate*

* If the vegetation covers <30% of the wetland, then the substrate is the principal characteristics

sub-class

persistent vs nonpersistent

Dominance

Dominant plant species (one that has control over the community)

Modifiers

describe more precisely:

a) water regime, e.g. tidal, subtidal, irregularly exposed

b) salinity

d) pH: acid < 5.5 circumneutral 5.5 - 7.4 alkaline > 7.4

c) soil, mineral and organic

e) special: excavated impounded -obstructs outflow diked -obstructs inflow partly drained farmed artificial

Canadian Classification system

1977

Goal: To describe Canadian wetlands uniformly

Canadian Wetland Definition:

Land that is saturated with water long enough to promote wetland or aquatic processes as indicated by poorly drained soils, hydrophytic vegetation, and various kinds of biological activity which are adopted to a wet environment

Canadian Wetlands structure

class → form → type

class

units easy to identify in the field (Bog, Fen, Marsh, Swamp, Open Water)

form

seventy bases on:

1. surface morphology

2. surface pattern

3. water type

4. morphology of underlying material

type

based on vegetation:

1. treed (coniferous, hardwoods)

2. shrub (tall, low, mixed)

3. moss

4. forb

5. graminoid (grass, reed, tall rush, low rush, sedge)

6. lichen

7. aquatic

8. non-vegetation

peatland

class

2-3 types

bog~ class

a) peatland with a water table at or near the surface

b) may be raised or level with surrounding terrain

c) virtually unaffected by groundwater

d) acidic and low in nutrients

May be treed (small trees) or treeless Usually covered with Sphagnum or ericaceous shrubs

Fen~ class

a) peatland with a water table at or near the surface

b) usually waters are nutrient rich & minerotrophic

Usually, vegetation consists of sedges, grasses, reeds, brown mosses, shrubs or trees

Marsh~ class

a) mineral wetland (shallow, well decomposed peat) that is periodically inundated by standing or slow-moving water

b) seasonal changes in surface water levels

c) waters are rich in nutrients varying from fresh to saline

d) show zonal or mosaic surface patterns composed of pools or channels interspersed with clumps of emergent sedges, grasses, rushes, reeds, bordering grassy meadows and peripheral bonds of shrubs or trees

swamp~ class

a) mineral or organic wetland with standing water or water gently flowing through pools or channels

b) pronounced internal movement, hence can be nutrient rich

c) dense cover of deciduous or coniferous trees or shrubs, herbs and some mosses

shallow open water~ class

a) intermittent or permanently flooded

b) mid summer depth of < 2m

Hydrogeomorphic Classification System