limnology exam 3 Flashcards
3 legal criteria used to define wetlands
1) water saturation: frequent or prolonged presence of water at or near the soil surface
2) Vegetation: adapted to wet/waterlogged soils
- is there vegetation present? have they adapted
ex: hydrophytes- there’s a federal list of species
3) presence of hydric soil
- soils presently soaked with water develop certain chemicals
- >waterlogged (saturated)
- >anoxic, high in organic matter content
wetland classificaitons based on vegitation
- emergent wetlands
- forested wetlands
- scrub/shrub wetlands
- shallow water/pond wetlands
emergent wetlands
plants have roots in water, but stems and leaves growing out of water-emerging out of water
- dominated by grasses, sedges, rushes, forbs (non-woody)
- marshes, wet meadows, fens
forested wetlands
trees present, saturated soils= swaps
scrub/shrub wetlands
oftern border a lake or stream
lots of shrubs, plants
have a little bit of everything
shallow water/pond wetlands
aquatic macrophytes present
hydrology based categorization of wetlands
fens
bogs
swamps/marshes
fens
mostly fed by groundwater
bogs
mostly precipitation fed
swamps/marshes
fed mostly by surface flow (streams, rivers, floodplains, beaver ponds)
Wetland functions
- Habitat-biodiversity hotspots
- flood attenuation
- Water quality
Wetland function: Biodiversity hotspots
Wetlands have lots of biodiversity
difficult to generalize
provide habitat for ducks- fish and wildlife habitat nursery
3/4 of WI wildlife species are dependent on wetlands
>1/3 of US threatened and endangered species live only on wetlands
so they are considered biodiversity hotspots
Wetland function: flood attenuation
wetlands are places to store water
act like a sponge
water enters quickly (during a flood) but leaves slowly
Wetlands function: water quality
1) reduce water velocity
2) Wetlands plants take up nutrients
3) waterlogged soil effects
4)Overall wetland effect on nutrients
5) Other consequences of waterlogged soils:
decomp slows
organic carbon
1) reduce water velocity
-> so sediments settle out
good for fish
good for P levels as P sticks to sediment particles, so P enters wetlands and may not leave
2) Wetlands plants take up nutrients
2) Wetlands plants take up nutrients- so no excess nutrients go into the environments
3)waterlogged soil effects:
in normal soils, soil particles + air pockets = lots of O2 all the way through the soil
but water logged soils are anoxic
waterlogging eliminates O2 form the soil, so therefore hydric soils are often anoxic
so usually in waterlogged soils, O2 is gone within millimeters
effects: No O2 -> Denitrification (NO3- -> N2 gas) eliminate nitrate from the soil
therefore wetlands prevent dead zones
Overall wetland effect on nutrients
wetlands can reduce (but not eliminate) sediments, excess nutrients
other waterlogged soils
water logging slows microbial respiration
Organic C + O2 -> CO2 + H2O
no O2 so different microbes present so less decomposition and so organic matter accumulates which is why these soils are so rich in organic matter
i.e they have a carbon storage function
Peat= partially decayed plant material
-about 40% of terrestrial C is stored in peat soils-
predominantlyy in N. America and Eurasia= arctic places
important for locking away carbon
-wetlands can have diverse plants Ex: sphagnum moss which stores for long periods of time, makes environment acidic, important for agriculture
-peat-> millions of years to coal
-arctic permafrost thaw: thaws so locked up C going back into Circulation
-Boreal peatland flow: burning organic C -> turns it into CO2
Channel form reflects a balance between?
channel form reflects a balance between
1, sediment inputs
2. channel slope-building dams changes this
3. the river’s hydrology
Stream and river habitat
water column:since there is a current= unidirctional fow
benthic zone: upper, well oxygenated sediment layer
hyporheic zone: mixing zone between stream water and groundwater. meet and miz below the benthic zone
riparian zone/floodplain: terrestrial-aquatic interface
Discharge
Q, units: m^3/s
volume of water passing through a channel cross-section per unit time
Q=V x A
Hydrograph
graph of discharge over time
Q vs time
Habitat
water column: since there is a current= directional flow
-benthic zone: upper well oxygenated sediment layer
hyporheic zone: mixing zone between stream water + groundwater meet and mix-below benthic zone
riparian zone/floodplain: terrestrial-aquatic interference
flow regime
-characteristic discharge pattern of a river over time: magnitude, frequency, duration, timing, rate of change
-reflects regional climate, geology, and human alterations to rivers
-can be used to identify determinants of stream community composition
-also used to access extent of human alteration
>change in flow regimes over time
ex: Illinios river- dam built, coal mining so they stabilized the river, and developed farm land around it