Wetlands Part 1

wetland ecosystems include

swamps, bogs, marshes, mires, fens, stream/river edges (Riparian zones)

swamps

trees + woody

bogs

• rain/snowmelt

• pH = acidic

• soil poor

• enclosed depression

• plants = carnivorous, unique spp.

marshes

grasses + herbaceous plants

fens

• ground H₂O

• pH = basic/alkaline

• soil rich

• spring, seep

• sedges

a bog or mire is

a wetland that is acidic (pH < 7)

a fen is

a wetland that is alkaline (pH > 7)

a swamp is

a wetland whose dominant vegetation is trees and woody plants

a marsh is

a wetland with other forms of vegetation dominant

not all wetlands

look “wet,” not water logged year round, just a significant time of year

wetlands are

dynamic ecosystems; productive (primary), dynamic (change) — dry/wet plants, prairie potholes, groundwater — aquifers (deeper)

many wetland species

adapted to periodic saturation and drying

prairie potholes

shallow/depressional wetlands; found in Northern Rocky Mountains in spring and summer

primary productivity

tells of how much photosynthesis is going on (biomass?)

wetlands often develop

in areas where water table is at/near surface

upland

away from water table (above H₂O)

water table

upper surface of groundwater below which soil is saturated with water that fills all voids

ecological value of wetlands

• high net productivity

• abundant and diverse wildlife

• water quality improvement

• flood and storm protection

things wetlands do

• trap sediment

• filter pollutants

• retain rainwater

wetlands are identified by

filed and remote investigations (GIS) using 3 criteria

hydrology

distribution and movement of water

3 criteria used in identifying wetlands

1. wetland (hydric) soils

2. hydrology

3. wetland vegetation

wetland (hydric) soils

soils that are H₂O saturated for extended periods during growing season; soil O₂ rapidly depleted due to chemical and biological O₂ demands

result of hydric soils

anaerobic conditions

lack of O₂ in hydric soil

leads to many effects on biological and chemical processes in soil

typical water sources for wetlands (hydrology)

tidal flow, precipitation, groundwater seeps, periodic flooding

hydroperiod

temporal pattern of H₂O’s fluctuation (regular or sporadic)

• strongly influences type of wetland that’s supported

hydrophytes

plants in wetlands; classified according to probability of occurrence

• OBL, FACW, FAC

obligate wetland plants (OBL)

high probability (>99%) of occurring in wetlands under natural conditions

facultative wetland plants (FACW)

usually occur (67-99%) in wetlands under natural conditions

facultative plants (FAC)

sometimes occur (33-67%) in wetland environments under natural conditions

wetland plants

specific adaptations allow them to outcompete upland plants in saturated soils

wet to dry plant scale

OBL → FACW → FAC → FACU → UPL

vegetation includes

~7,000 US species — cattails, sedges, rushes, cordgrass, mangroves, water plantains

carnivorous plants like pitcher and venus fly trap

is found in nitrogen poor soil

broad category classification for wetlands

riverine, palustrine, lacustrine

riverine wetlands

found in a valley or adjacent to a stream channel; they lie in the active floodplain of a river or stream and have important links to the water dynamics of the river system

palustrine wetlands

non-tidal wetlands substantially covered by emergent’s, trees, shrubs, moss/lichens, etc; total area is less than 20 acres

• most bogs, swamps, marshes, and wet meadows fall into this category

lacustrine wetlands

are associated with deep water habitats with the following characteristics:

• situated in a topographic depression or a dammed river channel

• lacking trees, shrubs, and other persistent emergent’s

• total area exceeds 20 acres

determination

what is and what is not a wetland is of significant ecological and economic importance

delineation

where a wetland is/is not

state and federal laws

generally require compensation (mitigation) for wetland loss

stakeholders:

1. industry: regulators, scientists, lawyers, engineers

2. landowners, politicians/judges and others influence this

mitigation can be

on-site, off-site, banking

principles for wetland mitigation

1. no net loss

2. type for type

3. preference for on-site mitigation

4. regulatory approval — TVA

• ex: boat dock approval

evolution of formal wetland definitions

the definitions has changed throughout the years through different laws/organizations

• 1950s → 2000s

• plants → soil → ecosystem

jurisdictional wetlands

meets the 3 criteria: hydric soils, hydrology, and wetland plants as established by the US Army Corps of Engineers (USACE)

• Clean Water Act (section 404), 1972

• Rivers and Harbors Act (section 10), 1899

section 404 (Clean Waters Act, 1972)

“discharge of dredged or fill material into waters of the US, including wetlands

section 10 (Rivers and Harbors Act, 1899)

“work or structures in or affecting navigable waters”

activities that may be regulated to protect wetlands

1. draining an agricultural wetland

2. installation of a water control source

3. dredging in a wetland (dredge + fill permits)

4. highway construction in a wetland

loss and degradation of wetlands

is mostly commonly from altered habitats

ex: wetlands turn into agricultural, residential, or business operations

• installing drain tile

• dredging operation

• extensive coastal development

significant loss of wetlands in USA

• states range from <1% to ~43%wetlands (AK)

• Alaska » vs. rest of US; some state have ~90% lost

AL wetlands

reduced by ½ in last ~200 years; occupies ~10% of area in state (Mobile-Tensaw River Delta)