Sand Dunes Flashcards
What type of deposition are sand dunes formed by?
Aeolian deposition- the entrainment of sediment by surface creep and saltation.
What are sand dunes officially known as?
They are officially known as psammoseres.
What do sand dunes rely on?
Fluid Threshold Velocity.
What is the Fluid Threshold Velocity?
This is where the strength of the wind is enough to move sand particles.
What are the 6 requirements for sand dunes to form?
Lots of sediment. Lots of wind energy. Fine sediment. Large tidal range. Large back shore.
What are xerophytes?
These are plants that can survive in areas with little water and sand.
What causes more and more vegetation to grow?
Plants die and pass on humus which allows more and more vegetation to grow.
What is humus?
Nutrients
What are pioneers?
These are plants that are able to survive in bare ground.
What is plant succession?
This is where plants invade and take over until an equilibrium is reached.
What starts plant succession?
Pioneer species.
How long does plant succession last for?
It may take hundreds of years to complete.
What is secondary succession?
This is when land has been exposed to human activities before plant succession takes place?
What is faster plant succession or secondary succession?
Secondary succession
What do pioneer species survive on exposed sites without?
They survive without competition.
What do pioneer species do to the environment?
They modify the environment by forming and binding soil.
What type of plants help the soil to retain moisture?
Creeping plants or those with leaf cover.
What allows other species to colonise?
The changes to the environment allow other species to develop.
What happens when other species colonise?
The pioneer species can no longer compete and therefore die out.
What will happen to the community if there are no limiting factors?
The final community will be adjusted to the climatic conditions which is known as the climatic climax community.
What is each stage of plant succession known as?
Each stage is a seral stage.
Why is it rare that plant succession reaches climatic climax?
Soil conditions, relief and drainage characteristics or the human management of the land may stop this.
What are the factors that stop a climatic climax being reached called?
Arresting factors.
What is developed instead of a climatic climax community?
A subclimax community.
What are the embryo dunes at Studland colonised with?
Sea crouch grass
Lyme grass
Marram grass
What is a property of Lyme grass?
It is salt resistant.
What is a key property of marram grass?
It can withstand dry weather.
What is a problem with marram grass?
It can’t survive in salt water.
What are the yellow dunes at Studland known as?
Zero Ridge
How long has Zero Ridge been around for?
About 50 years.
Is Zero Ridge mobile or fixed?
It is mobile.
What three plants can be found at Zero Ridge?
Red fescue
Sand sedge
Marram grass
What are the two fixed/ semi fixed dunes at Studland called?
Studland First Ridge and Second Ridge
What plants are found at Studland First Ridge?
Dandelions
Sea bind weed
Heather
Moss
What else can be found at Studland First Ridge?
Lichen
Butterflies
Lizards
What can be observed at Second Ridge?
Heather
Gorse
Not much marram grass
Thin line of humus
What do some parts of the Studland dune slack contain?
Stretches of water
What is the largest stretch of water at Studland called?
The Little Sea
What can be found at the Studland dune slack?
Small trees
Water loving plants
Aquatic animals
What trees can be found at Studland?
Birch
What water loving plants can be found at Studland dune slack?
Boy myrtle
What aquatic animals can be found at Studland dune slack?
Ducks
Has Studland got a climax community?
It has a climatic climax community and and the area of Studland Heath would take over the area if trees were not deliberately cut.
What are the trees deliberately cut at Studland Heath?
To maintain the diversity of the habitats.
What are sand dunes?
These are small ridges or hills of sand that are found at the top of a beach, above the usual maximum reach of waves.
Why are sand dunes important?
They are important ecosystems.
What are sand dunes vulnerable to?
Erosion by both natural and human processes.
What is a key characteristic of embryo and fore dunes?
Poor water retention
What deposits humus on embryo and fore dunes?
Seaweed
How hi are embryo and fore dunes?
About 1m high
How much sand is exposed in embryo and fore dunes?
About 80%
What is the soil like in embryo and fore dunes?
The soil is alkaline.
What are the plant characteristics at embryo and fore dunes?
Long roots with underground shoots
Add organic matter which aids water retention
Waxy leaves maintain moisture and withstand wind
Low to avoid winds
High salt tolerance
What are the key characteristics of yellow dunes?
They are more water retentive
Little vegetation or organic matter
Beyond the reach of normal tides
Reduced wind speed
How high are yellow dunes?
5m high
How much sand is exposed in yellow dunes?
About 20%
What is the soil like at yellow dunes?
It is less alkali.
What are the plant characteristics?
Salt tolerant Thrive when buried in sand Leaves are rolled up to reduce moisture loss Long roots Rhizomes stabilise the sand
What are three example plants that can be found at yellow dunes?
Rag wort
Red fescue
Sand sedge
What are the main characteristics of grey dunes?
Sheltered
More vegetation cover
Little mobile sand
Sand no longer accumulating
How much humus is found at grey dunes?
Grey dunes have a high humus content.
How high are grey dunes?
They can reach heights of up to 20m.
How much sand is exposed at grey dunes?
Less that 10% of the sand is exposed.
What type of plant is there less of at grey dunes?
There is less marram.
What makes grey dunes grey?
Surface lichen
What are the two key plant characteristics at grey dunes?
Higher species diversity
Mainly perennials
What are dune slacks?
These are depressions in the dunes where the water table is on or near the surface.
What causes the depressions in dune slacks?
The calm air behind the dunes.
What is the soil like at dune slacks?
Damp and acidic
What are the plants like at dune slacks?
Plants that are also found in fresh water wetlands.
Give 3 example plants that can be found at dune slacks.
Rushes
Phragmite reeds
Big cotton
What are the characteristics of Heath/woodlands?
The supply of sand is cut off or reduced. Well sheltered from winds Lots of humus Nutrient rich Minimal influence by maritime.
What is the soil like at heaths and woodlands?
It is acidic
What are the two plant characteristics?
Perennials
Scattered trees
Give two example plants that can be found at Heath/ woodlands.
Heather
Sea buckthorn
What is meant by ridges?
These are sequences of dune parallel to the coastline.
What are blowouts?
These form when fragile sand dunes have their vegetation destroyed by grazing animals such as by rabbits and human activity.
What type of human activity can damage sand dunes?
Trampling
