Wetlands Flashcards
How are woodlands formed?
By succession, a gradual directional change in the composition of the vegetation, populations successively replace one another
What are the two types of wetland ecosystems?
Shallow water and wet terrestrial
What are the two types of telmatic woodland?
Epheemral (marsh) and stable (swamp, bog, fen)
What is allogenic succession?
When succession is driven by environmental change (other-made)
What is autogenic succession/
When the vegetation itself induces environmental change, and creates conditions conducive to its own replacement (self made)
What is primary succession?
On surfaces that have not previously supported vegetation
What is secondary succession?
On surfaces that have previously supported soil and vegetation
What are the main processes by which peat accumulates?
Terretrialisation - infilling of lakes and pools, paludification - dry land gets wetter
How is paludification induced?
various influences e.g. impeded drainage caused by sea-level rise, increased precipitation
What is rooting?
water gradually shallows by the accumulation of mud and peat
allows progressive colonisation by species more suited to shallow- water conditions
What is rafting?
Open water becomes overgrown by a buoyant raft of peat, reducing the dependancy of succession on shalllowing caused by accumulation of mud
How does rooting succession occur?
1- infilling of open water 2- swamp 3- fen 4- fen woodland 5- dry deciduous woodland
How does a raised bog form?
Acidic ombrotrophic peat accumulates above the level of the fen water table, Often found in small, sheltered basins
How do raised bogs differ from rooting?
the swamp and fen phases develop by direct colonisation of open water and water body tends to fill up top- downwards.
How did the Atlantic period cause formation of blanket bog?
ombrogenous formation
named because of its capacity to ‘blanket’ terrain
restricted to oceanic regions with wet and cool climates
How is most blanket bog initiated?
By forest clearance
What are the features of waterlogged environments?
Saturated with water
oxygen deficient - hypoxic/anoxic
redox related chemical changes affecting nutrient availability
What conditions of wetlands help retard decomposition?
Anoxic, abundant toxins, very acidic, means peat is produced, and bog bodies
Why is water logging a problem for plants?
oxygen deficiency and increased availability of phytotoxins
How are plants adapted to overcome oxygen deficiency?
Anaerobic respiration in roots
transport of oxygen to roots
release of oxygen into rhizosphere
How are some plants adapted for anaerobic respiration?
Accumulate less toxic malic acid rather than ethanol
How is high porosity provided for optimum oxygen saturation of the tissues?
arenchyma
cavities and channels
special oxygenating structures
What are pneumatophores?
upward growing roots, take air directly into the rooting system
How may oxygen of the rhizosphere occur?
diffusion of oxygen out of the root enzymic oxidation of the root surface, creating a small oxidised rejoin around the root
dead stems may act as snorkels
