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Transcript of Psammoseres
Succession in sand dune vegetation (coastal dune belts).
This is a type of plant succession which is a series of seral stages in a place over time, from pioneer communities to a climax community. Conditions for a psammoseres to take place:
A plentiful supply of dry sand.
Strong offshore winds to help blow the sand(at least 16 mph).
An obstacle to help trap the sand, usually a plant.
Plants must adapt to an environment which is: dry, salty, mobile and lacking in nutrients
Ideally, low, near shore slopes with space for sand to dry out at low tide.
This means that.... Dunes cannot grow if... ...the wind velocity is too low.
... the sand is too damp.
... there is too much vegetation.
…there are strong stormy high tides and the use of beaches by people.
…there are not enough nutrients.
...plants are not drug resistant, as sand dries very fast.
Characteristics of a psammosere: Psammoseres show effectively this succession of stages form pioneers species to a climax community:
Dunes result from the transport of sand by wind
May be found in a zone up to 10km wide inland
Dune height: from 1 to 30m
The upwind side (stoss) is steeper than the downwind (lee) slope
500+ vegetation types grow there.
In Scotland there are 5000 ha of partly vegetated sand
stoss lee A sand dune system may take hundreds of years to develop but the process can be seen within a few hundred metres of the shoreline: Pioneer Stage 1.Seeds are blown in by the onshore wind or washed in by the sea.
2.Drought, strong winds and salty seawater make rooting conditions poor, though seaweed acts like humus build up.
3.The wind moves sand in the dunes and this allows rainwater to soak through rapidly.
4.Small new dunes develop by alkaline sand due to seashells.
Vegetation adapts to such conditions:
•Scattered to take advantage of scarce nutrients and water.
•Low to avoid strong winds
•Waxy leaves to retain moisture
•Deep roots to maximize water absorption.
sandwort sea couch grass
1.Plant’s roots trap sand, binding it together. Grey dunes are fixed.
2.The humus by decaying pioneer plants creates more fertile growing conditions.
3.Less enduring plants grow.
4.New colonizers make sand disappears and the dunes change color from yellow to grey.
Building stage (yellow and grey dunes):
In yellow dunes:
•In-rolled leaves to reduce moisture loss
•Long tap roots
•Other plants such as Ragwort, Red fescue and Sand sedge begin to appear, mainly Marram grass.
In grey dunes:
•higher species diversity
•lichens and heather
Taller plants and more complex plant species.
Plants from earlier stages die out because of competition for light and water
When the water table reaches, or nearly reaches the surface, dune slacks can occur
Plants which are specially adapted to be water-tolerant and acid loving grow here.
Climax stage (Dune slack and dune heath)
Located on the North West corner of Northern Ireland, from Downhill to Magilligan Point, in the Republic of Ireland.
The beach started to develop as a result of sea and land level changes after the last ice age. Ireland’s largest coastal accumulation feature: 32 square kilometres of sand deposits.
Uses of the dunes behind the beach:
•Used by the Ministry of Defence as a firing range and prison.
•Small golf course and several caravan parks.
•Managed by Nature Reserves.
Case Study: Magilligan Beach Yellow dunes Grey dunes