wetlands

hydrology & physiography wetland habitats

• crucial to waterfowl, wildlife and plant life

• provide vital ecosystem services such as waste purification and flood control

• most endangered aquatic habitat

value of wetlands

• filters water

• C sequestrion

• intrinsic value

• supports waterfowl- biodiversity

• controls floods downstream

• nutrient cycling

history & wetlands

• Rivers and Harbors Act- 1899, unlawful to dredge or fill US waters without a permit

• Emergency Wetland Protection Act- 1986, established the no net loss policy, requires a 10-year report to congress, made gov organizations come up with a unified method for delineating wetlands

• today, the COE permits filling or dredging of wetlands after the EPA certifies that the activity will not negatively affect the water quality of the wetland

• USFWS is involved because lots of endangered species live in wetlands

USFWS wetland definition

• at least periodically, the land supports predominantly hydrophytes

• the substrate is predominantly undrained hydric soil

• the substrate is nonsoil and is saturated with water or covered by shallow water at some time during the growing season of each year

its the water (hydrology) that affects the soils (hydric soils) and modifies the vegetation (hydrophytic plant species)

types of wetlands

• salt marsh: influenced by tides or other water fluctuations

• mangrove swamps

• freshwater marsh: inland wetland dominated by grass

• tidal freshwater marsh: influenced by tides but out of reach of saltwater

• deepwater swamp: water most of the season, forested

• prairie potholes: shallow glacial depressions

• riparian wetlands: near rivers

• lacustrine wetland; “near a lake”

• palustrine wetland: in a topographic low place

wetland hydrology

• area is inundated or saturated to the surface for at least 5% of the growing season in most years

  • growing season is based on soil temp and is determined for regions by the USDA

  • most years= 51/ 100 years

• WETLANDS ARE NOT ALWAYS WET

hydrologic regimes

• timing, amount, and source of water matter as do the permanence, predictability, and seasonality of the water

  • water flow may be bidirectional (tides, unidirectional (rivers), or periodic

• predator permanence gradient- wetlands that hold water longer tend to have more predators

field indicators of wetland hydrology

• inundation

• soil saturation at 12 inches or less

• watermarkers

• deposition of water-borne debris

• deposits of water-borne sediments

• drainage patterns within wetland

• water stained leaves

• morphological adaptations of plants

hydrophytic vegetation

• plant species that are adapted for life in saturated soils

  • anaerobic soil conditions

  • soggy or waterlogged soils

    • require adaptations for better support

    • require adaptations or gas exchange

• hydrophytes are plants growing in water or on substrates that are periodically deficient in oxygen

hydrophytes

• plants classified by tendency to occur in wetlands

  • obligate: almost always occur it wetlands (>99%)

  • facultative wet: usually occur in wetlands (67-99%)

  • facultative: equally likely to occur in wetlands or non-wetlands (33-67%)

  • facultative up: usually occur in non-wetland (67-99%) but occasionally in wetlands (1-33%)

  • upland: almost always occur in non-wetlands (>99%)

hydric soil

• a soil that is saturated, flooded, or ponded long enough during the growing season to develop anaerobic conditions in the root zone

  • tend to be darker in color and have mottles of iron staining

wetland functions

• the physical, chemical, and biological interactions within wetlands are often referred to as wetland functions

  • water filtration & purification

  • trapping sediments and contaminants

  • flood control and stream flow regulation

  • erosion reduction

  • habitat for aquatic and terrestrial plants and animals

  • geologic function/ mitigate climate change

wetland loss

• the loss of wetland area, due to the conversion of wetland to non-wetland habitats, as a result of human activity

• 22 states have lost at least 50% or more of their original wetlands

• 70% of US riparian wetlands lost

• 50% of prarie potholes gone

• california has lost the largest percentage of original wetlands within the state (91%)

• half of everglades drained

• florida has lost the most acreage (9.3 million acres)

• cameroon (80%), new zealand (90%), australia (95%), thailand (96%), vietnam (>99%)

impact of wetland loss

• has diminished to the point where environmental and socio-economic benefits are now seriously threatened

• floods are more devastating because there are fewer wetlands to soak up the water

• it is estimated that restoring 6% of wetlands in flood- prone areas and relocating homes and businesses, would largely eliminate costly floods in the midwest