Wetland Science

Wetland scientists examine:

- biology

- characteristic plants andanimals, microorganismsof different wetland types

- vulnerability to disturbance

- adaptations to wetland conditions

- flooding, low oxygen levels

- chemistry- chemicals characteristic of wetland

conditions - low or no oxygen- pH- nitrogen and phosphorus

cycling- sulfur cycling- iron and manganese

transformations underdifferent oxygen levels

-geology- soil formation processes

- geochemistry- organic matter content

-hydrology – water cycle- sources, chemistry

Mineral soils

Organic soils

Defining wetlands

What features characterize a wetland?

-lowland areas

- might be transitional between terrestrialand aquatic habitats- can occupy isolated basin

- covered with shallow, temporary or intermittent waters

- water might be present at the surface, or within root zone

- soils often rich in organic matter, anoxic (no/low oxygen)

- possess plants adapted to wet conditions

Diversity of wetland types - makes defining/describing specific wetlands difficult

- freshwater wetlands- forested swamps, blackwater and whitewater floodplain swamps, cypress, hardwood-dominated,bay swamps, shrub bogs, hydric hammock,fen,- marshes, bog, depression marsh, marl prairie, wet prairie, potholes, playa

- coastal wetlands- mangroves, salt marsh (Juncus-or

Spartina-dominated),tidal freshwater marshes

For instance, in Florida

freshwater – 4 main categories of wetlands

- seepage wetlands- floodplain wetlands- basin wetlands

- 15 different types

- wet flatlands – 4 types

marine/estuarine – tidal marsh & tidal swamp

21 different types of wetlands – defined byFlorida Natural Areas Inventory (FNAI)- used in wetland delineation, conservation

Defining Wetlands- definitions/terminology of different types vary from

vaque -> very specific

- not all wetlands have same properties- still young, developing field with much to learn

- function/roles- diversity/habitat – regional variation- natural variation through time- resilience to disturbance

- multidisciplinary approach to scientific study biology, chemistry, geology- management/protection requires sound

science

- value system- land for development – residential, commercial

- agricultural, etc.- natural areas- habitat/biodiversity protection–> balance not easy to achieve

-wetland restoration – works for some wetlands, not always the best

solution

-many different types, many definitions, some confusing (contradictory?)

-older classification - simplistic, didn’t emphasize unique qualities

-laws for regulation, protection -> requires clearer classification- scientific input important

- clarification of different categories- management- protection

Features of Wetland

1) water, at surface or root zone - shallow- depth and duration of flooding - variable- some continually flooded, others briefly

or with minimal flooding- water levels can vary within a wetland, shifting apparent ‘boundaries’ seasonally

or annually

2) ecotone (transition zone) between open water and terrestrial systems – applies to many wetlands- margins - share properties of both- some scientists do not recognize wetland as

distinct ecosystem

3) defined by specific plant types- animals, plants and microorganisms vary - some tolerant of wet and dry conditions, others require wet conditions- indicator taxa - might not always be easy to define

4) variable in size - few acres -> large tracts

5) range from coastal -> inlandstructure and function vary from wetland to wetland

6) human impact varies depending on location- rural - agricultural impact – non-point

sources of nutrients

- urban – pollution (often point source) modified watershed & hydrology

result of variation-> one good definition doesn’t exist!

Why definitions needed?

- wetland scientists - need definition that helps promote wetland study/differentiation

- flexible, but clear- classification- research- inventory plants and animals

- wetland managers/regulators- laws/regulations- need definition with clear language,

legally binding

Scientific definitions

- Wetland definitions are lacking from most contemporary ecology textbooks

- Limnology texts often include some definition:

ex. Dodson, 2005

“..characterized by soil saturated with water,but with standing water less than 1 m deep,

often with extensive areas of floating or emergentvegetation. Wetlands are also called marshes orcarrs. Swamps have trees standing in water.

Wetlands can be lentic or lotic.”

Scientific definitions

1)U.S. Fish and Wildlife Service - Circular 39, 1956

The term wetlands refers to lowlands covered withshallow and sometimes temporary or intermittentwaters. They are referred to by such names as marshes, swamps, bogs, wet meadows, potholes,sloughs, and river-overflow lands. Shallow lakes and ponds, usually with emergent vegetation as a conspicuous feature, are included in this definition, but the permanent waters of streams, reservoirs, and deep lakes are notincluded. Neither are water areas that are so temporary as to have little or no effect on the development of moist-soil vegetation.- early definition, but useful

Later definition – 1979

Wetlands are lands transitional between terrestrial and aquatic systems where the watertable is usually at or near the surface or that 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; and3) 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.

introduced important concepts

- hydrophytes - plants adapted to wetconditions

- hydric soils - soils formed during conditionsof saturation, flooding, or ponding longenough during the growing season todevelop anaerobic conditions in the upper part.

- general, flexible, comprehensive definition- includes plants, soils, hydrology

- easier for scientists to use than managers- does promotes classification, inventory

2) U.S. National Academy of Sciences - 1990s-National Research Council Committee

- scientific review of past definitions

- regional variation

- scientific ability to analyze wetland properties

“A wetland is an ecosystem that depends on constant or recurrent, shallow inundation or saturation at or near the surface of the substrate. The minimum essential characteristics of a wetland are recurrent, sustained inundation orsaturation at or near the surface, and thepresence of physical, chemical, and biologicalfeatures reflective of recurrent, sustainedinundation or saturation. Common diagnostic features of wetlands are hydric soils andhydrophytic vegetation. These features will be present except wherespecific physiochemical, biotic, or anthropogenicfactors have removed them or prevented their development.”

- most comprehensive definition

- common diagnostic features – broader, more flexible than

previous definitions

3) International definition

- International Union for the Conservation of Natureand Natural Resources – 1971

Ramsar Convention Definition

Areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary,with water that is static or flowing, fresh, brackish, or salt including areas of marine water, the depth of which at low tide does not exceed 6 meters.

- includes a lot left out by U.S. - river and coastal zones- depth greater than most definitions

-advantage - included habitat used by migratorybirds

Legal definitions- 1970's U.S. Army Corps of Engineers

- Clean Water Act “dredge and fill” program

U.S. Natural Resources Conservation Service

‘Swampbuster’ provision - Food Security Act

-both designed for wetland protection

1)U.S. Army Corps of Engineers - 1984 definition

“The term wetlands means those areas that areinundated or saturated by surface or ground water at a frequency and duration sufficient to support, and under normal circumstances do support, a prevalence of vegetation typicallyadapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs and similar areas.”

-Controversial - debated in courts

-has had rewording over the years - clarify vegetation covered

Wetlands - considered part of the waters of U.S. - since 1975, regulated by U.S. Army Corps of Engineers- review/regulated dredge-and-fill permits

- some citizens/companies have bypassed permit process by destroying aquatic plants

- included groundwater-supported wetlands

2) Food Security Act Definition - 1995-wetlands in agricultural areas received protection in1985“ The term “wetland” except when such term is partof the term “converted wetland” means land that -A) has a predominance of hydric soils;B) is inundated or saturated by surface orgroundwater at a frequency and duration sufficient to support a prevalence of hydrophytic vegetationtypically adapted for life in saturated soil conditions; andC) under normal circumstances does support aprevalence of such vegetation. For purposes of this Act and any other Act, thisterm shall not include lands in Alaska identified as having high potential for agricultural development which have a predominance of permafrost soils.”

-hydric soils - key component

- excludes Alaska - not science-based, butpolitical – allows development of wetlandareas in Alaska

Jurisdictional wetlands - legally defined wetlandsin U.S. under the jurisdiction of the Clean Water Act (Section 404), or the swampbuster provision of Food Security Act- both definitions emphasize different things

- Corps - plants determine wetland presence-designed for quick use to determinejurisdiction

- FSA - hydric soils- excludes non-hydric soils, and Alaska

-many wetlands recognized by scientists may fit into legal definitions, not all- ex. riparian wetlands

Goal - delineate wetlands and boundaries- ease, quick assessment- clear, comprehensive- user-friendly- standard protocols for identifying wetlands

plants or soils (wetland delineation)

Florida StatutesChapter 62-340, Florida Administrative Code, Delineation of the Landward extent of Wetlands and Surface Waters, subsection373.019(17)

“Wetlands means those areas that are inundated or saturated bysurface water or ground water at a frequency and a duration sufficient to support, and under normal circumstances do support, a prevalence of vegetation typically adapted for line in saturatedsoils. Soils present in wetlands generally are classified as hydricor alluvial, or possess characteristics that are associated with reducing soil conditions. The prevalent vegetation in wetlands generally consists of facultative or obligate hydrophytic Macrophytes that are typically adapted to areas having soil conditions described above. These species, due to morphological, physiological, or reproductive adaptations, have the ability to grow, reproduce or persist in aquatic environments or anaerobic soil conditions. Florida wetlands generally include swamps, marshes, bayheads, bogs, cypress domes, strands, sloughs, wet prairies, riverine swamps and marshes, mangrove swamps and other similar areas. Florida wetlands generally do not include longleaf or slash pine flatwoods with an understory dominated by saw palmetto.”

one definition - probably not possible nor practicalconsidering the objectives differ depending onuser.

-ecological, inventory purposes-U.S. Fish and Wildlife Service definition most

accepted

- regulatory - U.S. Army Corps of Engineers definition