wetlands 1

why are wetlands important

water supply, flood mitigation, nutrient and sediment retention, shoreline protection, food production (rice, cranberries, grazing) fiber, carbon sequestration, horticulture products (peat), construction materials (mud, thatch, aesthetics, recreation, cultural

define a marsh

a mineral rich wetland where the dominant vegetation is herbaceous plants rooted in hydric soils but not in peat. they are fed from upland drainage making them nutrient rich and highly productive. more herbaceous plants not woody

define bogs

nutrient poor, acidic wetlands that are dominated by sphagnum mosses, sedges, shrubs and evergreen trees rooted in deep peat. Bogs are dependent on rain for majority if their water supply. they rely on windblown particles for mineral nutrients

define fens

similar to bogs because they have peat souls but they receive water from surrounding watersheds in streams and groundwater. this causes then to be less acidic. they tend to be dominated by sedges

define swamps

freshwater wetlands dominated by trees rooted in hydric soils.

define a wetland

varied definitions but commonly touch on the presents of water at the surface or the rooting zone, unique soil conditions and the support of unique vegetative communities

list the types of inland wetlands

freshwater marsh, peatland, freshwater swamp, riparian wetland, vernal/ temporal pool

list the types of coastal wetlands 

tidal salt marsh, tidal freshwater marsh, mangrove wetland 

what are some threats to wetlands

drainage, dredging, development, agriculture, nutrient inputs, climate change, invasive spp, cumulative impacts 

define a freshwater marsh

mineral soils, dominated by grasses, reeds, sedges and floating aquatic plants

define a tidal freshwater marsh

reduced salt stress leads to higher diversity than salt marshes, dominated by grasses and annual/ perennial broad-leafed aquatic plants 

define salt marsh

located in intertidal areas, can be marine or river dominates and have hydrophytic vegetation

define freshwater swamps

heavily forested, perennially flooded or alluvial swamps flooded by adjacent streams and rivers

riparian wetlands

soil and soil moisture are influence by rivers and streams

define a mangrove swamp

in the tropics and subtropics, replace tidal salt marshes in the tropics, low vegetation and spp diversity

define peatlands 

require a positive water balance and peat accumulation (creates anoxic conditions) large carbon sinks 

vernal/ temporary wetlands

shallow and seasonally flooded, veg varies from wet meadow to forested, highly diverse flora and fauna

what are the three factors in wetland delineation

1. hydrophytic vegetation 

2. hydric soils 

3. wetland hydrology 

what is hydrophytic vegetation

a plant community dominated by hydrophytes.

hydrophytes are plans that are adapted to the physical and chemical conditions found in wetlands that express dominance under these conditions

what are the classes of wetland indicator status for plants 

obl- obligate wetland plants - almost always in wetlands 

facw- facultative wetland plants- usually in wetlands but can be elsewhere 

faxc- facultative plants- occur in wetlands and non-wetlands 

facu- facultative upland plants- usually occur in non-wetlands but can occur in wetlands 

upl- upland plants- almost never occur in wetlands 

what are the two types of hydric soils

organic and mineral

define the types of organic hydric soils

histosols- organic matter

muck also known as saprosts- 2/3 is decomposed and less than 1/3 of plant fibers are identifiable

peat- in which less tan 2/3 if the material is decomposed and 2/3 of the plant fibers are identifiable

mucky peat or peaty muck- the ratio of decomposed to identifiable plant matter is basically even 

what are the three factors in soil color

hue- main color spectrum

value- degree of lightness 

chroma- indicated the strength or purity of color 

• matrix chroma of 2 or less in mottled soils ‘

• matrix Chroma of 1 or less in unmottled soils 

what are two of the hydric soil indicators 

gleying= bluish grey soil

mottles- orange/ red oxidized iron

what are some signs of problem soils

spodosols- nutrients have leached out of base layer, can create cemented layer

plow layers- human disturbance 

red or grey soils 

sandy or coarse soils- water drains 

what are the primary indicators of wetland hydrology

1. visual observation of flooded area 

2. visual observation of soil saturation 

3. water marks 

4. drift lines 

5. water-borne sediment deposits 

6. wetland drainage patterns 

what are the secondary indicators of wetland hydrology

1. oxidized rhizospheres 

2. water stained leaves

3. surface scoured areas 

4. dead vegetation 

what are the major components of hydrologic budgets for wetlands 

precipitation

surface inflows and outflows 

groundwater 

evapotranspiration 

tides 

terrestrial plant adaptions

needed adaptions to resist drying out, exchange gasses with the atmosphere, transport water and nutrients and stay upright 

list the 4 aquatic plant zones

1. emergent- roots and stems are in shallow water 

   1. emergent hydrophytes are the highest biomass and productivity

2. floating- leaves float on the water surface 

   1. rooted floating hydrophytes are adapted to heterophylly

3. algae- non-vascular 

4. submerged- whole thing is under water 

   1. require water for support

differentiate between sedges, rushes and grasses

• sedges-

  • triangular (have edges)

  • no joins, wetland indicator

• rushes

  • round

  • solid 

• grasses 

  • hollow 

  • have joints 

adaptions to fluctuating water levels

heterophylly (diff sized leaves)

emergent leaves to maximize light capture 

rounded leaves- stomata on upper surface, more stable, thicker leaves help to prevent tearing also minimized drag from currents,

adaptions to obtaining oxygen in roots 

oxygen gets channel to roots via diffusion and then leaks out of root into surrounding sediment that sediment has redox potential which increased the nutrient cycle. this process can help to detoxify harmful compounds and creates a micro- oxygenated zone around roots that help to create a better rhizosphere

submerged plants use larger surface area to help direct gas exchange 

can form adventitious roots or shallow roots or pneumatophores (cypress knees) prop or drop roots

what is aerenchyma 

air channels that are used as rapid has exchange pathways (diffuse through porous tissues)

in a cattail ½ the leaf volume is gas storage

what is a lacunae

a gas filled space

what are some stem adaptions to obtaining oxygen

stem elongation and buoyancy

what are some avoidance tactics used in oxygen

avoid anoxia by timing active growth or seedling establishment to avoid flooding 

Reduce your metabolism in winter to avoid oxygen deprivation 

avoid low oxygen periods and then grow quickly with stored carbon and nutrients 

what are some strategies for limited light 

1. chloroplast on leaf structure 

2. A higher concentration of chlorophyll 

3. increase surface area exposed to light (ribbon like leaves)

4. grow towards the light (apical growth is a cluster closest to the light) 

5. start really early 

strategies for limited carbon

similar strategies to light and oxygen

Use bicarbonate when CO2 is limited

and assimilate carbon dioxide by diffusion at night when it is more plentiful

Carbon dioxide can also be recycled in the aerenchyma (must maintain internal co2 pressures higher than external pressure)

sediment-derived co2

diffusive boundary layer- submerged plants have no stomata so they get by with molecular diffusion

what are some strategies for limited nutrients

obtaining: mycorrhizal associations, nitrogen fixation, carnivory

conserving: nutrient translocation, evergreen leaves

strategies for toxin accumulation 

stem hypertrophy - formation of aerenchyma causes swelling of the stem near the base, increases aeration through the stem, and is a secondary benefit of buttressing tree roots

lenticels- allow gas exchange

venturi and humidity-induced convection- dead stems remain standing, and new growth grows underneath

. Anaerobic respiration- the accumulation of pyruvate and NADH is toxic. Fermentation converts pyruvate into ethanol or lactate, which regenerates nad+, which allows glycolysis to continue

strategies for salt stress 

Salt-tolerant plants have less concentrated cells, making water move against the osmotic gradient, requiring energy

. C4 photosynthetic plants use PEP carboxylase to increase CO2 uptake, and close the stomata more often to reduce water loss. separates photosynthetic reactions in space 

CAM plants separate photosynthetic reactions in time. close stomata even more often to reduce water loss and respire photosynthetic oxygen 

They can also filter salt out during water uptake 

can have salt glands in leaves to selectively remove ions

strategies for reproduction

good at asexual reproduction

• fragmentation

• rhizomes

• stolons

submerged plants have to reproduce underwater (very few examples of sexual reproduction in that case)

why is wetland hydrology important

it drives the physical conditions ( flooding, oxygen, water chemestry, sediment chemistry) it also determines the types of organisms that can survive

list the water flow paths 

subsurface flow- through surface soils, increases post flood, declines rapidly 

Overland flow- variable, increases rapidly after rainfall, declines rapidly, responsible for flash flooding 

baseflow- least variable, increases slightly after floods, groundwater 

what defines a wetland water budget

inputs: precipitation, surface inflow, groundwater inflow, tidal inflow

outputs: evapotranspiration, surface outflow, groundwater outflow, tidal outflow

factors that influence hydrology

abiotic: geomorphology, climate, geology, soils

biotic: vegetation type/cove, animal activity, human activity

seasonality of hydrography varies with climate and watershed size

vegetation impacts on hydrology 

hydrology: trap and bind sediments, transpire moisture, interrupt water flow 

physical env: shading, trapping sediment, retaining nutrients, building peat

microbes control nutrient availability and influence most chemical processes in wetland soils and the water column