Sand Dunes Flashcards

1
Q

What type of deposition are sand dunes formed by?

A

Aeolian deposition- the entrainment of sediment by surface creep and saltation.

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2
Q

What are sand dunes officially known as?

A

They are officially known as psammoseres.

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3
Q

What do sand dunes rely on?

A

Fluid Threshold Velocity.

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4
Q

What is the Fluid Threshold Velocity?

A

This is where the strength of the wind is enough to move sand particles.

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5
Q

What are the 6 requirements for sand dunes to form?

A
Lots of sediment. 
Lots of wind energy. 
Fine sediment. 
Large tidal range. 
Large back shore.
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6
Q

What are xerophytes?

A

These are plants that can survive in areas with little water and sand.

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7
Q

What causes more and more vegetation to grow?

A

Plants die and pass on humus which allows more and more vegetation to grow.

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8
Q

What is humus?

A

Nutrients

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9
Q

What are pioneers?

A

These are plants that are able to survive in bare ground.

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10
Q

What is plant succession?

A

This is where plants invade and take over until an equilibrium is reached.

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11
Q

What starts plant succession?

A

Pioneer species.

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12
Q

How long does plant succession last for?

A

It may take hundreds of years to complete.

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13
Q

What is secondary succession?

A

This is when land has been exposed to human activities before plant succession takes place?

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14
Q

What is faster plant succession or secondary succession?

A

Secondary succession

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15
Q

What do pioneer species survive on exposed sites without?

A

They survive without competition.

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16
Q

What do pioneer species do to the environment?

A

They modify the environment by forming and binding soil.

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17
Q

What type of plants help the soil to retain moisture?

A

Creeping plants or those with leaf cover.

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18
Q

What allows other species to colonise?

A

The changes to the environment allow other species to develop.

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19
Q

What happens when other species colonise?

A

The pioneer species can no longer compete and therefore die out.

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20
Q

What will happen to the community if there are no limiting factors?

A

The final community will be adjusted to the climatic conditions which is known as the climatic climax community.

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21
Q

What is each stage of plant succession known as?

A

Each stage is a seral stage.

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22
Q

Why is it rare that plant succession reaches climatic climax?

A

Soil conditions, relief and drainage characteristics or the human management of the land may stop this.

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23
Q

What are the factors that stop a climatic climax being reached called?

A

Arresting factors.

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24
Q

What is developed instead of a climatic climax community?

A

A subclimax community.

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25
Q

What are the embryo dunes at Studland colonised with?

A

Sea crouch grass
Lyme grass
Marram grass

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26
Q

What is a property of Lyme grass?

A

It is salt resistant.

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27
Q

What is a key property of marram grass?

A

It can withstand dry weather.

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28
Q

What is a problem with marram grass?

A

It can’t survive in salt water.

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29
Q

What are the yellow dunes at Studland known as?

A

Zero Ridge

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30
Q

How long has Zero Ridge been around for?

A

About 50 years.

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31
Q

Is Zero Ridge mobile or fixed?

A

It is mobile.

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32
Q

What three plants can be found at Zero Ridge?

A

Red fescue
Sand sedge
Marram grass

33
Q

What are the two fixed/ semi fixed dunes at Studland called?

A

Studland First Ridge and Second Ridge

34
Q

What plants are found at Studland First Ridge?

A

Dandelions
Sea bind weed
Heather
Moss

35
Q

What else can be found at Studland First Ridge?

A

Lichen
Butterflies
Lizards

36
Q

What can be observed at Second Ridge?

A

Heather
Gorse
Not much marram grass
Thin line of humus

37
Q

What do some parts of the Studland dune slack contain?

A

Stretches of water

38
Q

What is the largest stretch of water at Studland called?

A

The Little Sea

39
Q

What can be found at the Studland dune slack?

A

Small trees
Water loving plants
Aquatic animals

40
Q

What trees can be found at Studland?

A

Birch

41
Q

What water loving plants can be found at Studland dune slack?

A

Boy myrtle

42
Q

What aquatic animals can be found at Studland dune slack?

A

Ducks

43
Q

Has Studland got a climax community?

A

It has a climatic climax community and and the area of Studland Heath would take over the area if trees were not deliberately cut.

44
Q

What are the trees deliberately cut at Studland Heath?

A

To maintain the diversity of the habitats.

45
Q

What are sand dunes?

A

These are small ridges or hills of sand that are found at the top of a beach, above the usual maximum reach of waves.

46
Q

Why are sand dunes important?

A

They are important ecosystems.

47
Q

What are sand dunes vulnerable to?

A

Erosion by both natural and human processes.

48
Q

What is a key characteristic of embryo and fore dunes?

A

Poor water retention

49
Q

What deposits humus on embryo and fore dunes?

A

Seaweed

50
Q

How hi are embryo and fore dunes?

A

About 1m high

51
Q

How much sand is exposed in embryo and fore dunes?

A

About 80%

52
Q

What is the soil like in embryo and fore dunes?

A

The soil is alkaline.

53
Q

What are the plant characteristics at embryo and fore dunes?

A

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

54
Q

What are the key characteristics of yellow dunes?

A

They are more water retentive
Little vegetation or organic matter
Beyond the reach of normal tides
Reduced wind speed

55
Q

How high are yellow dunes?

A

5m high

56
Q

How much sand is exposed in yellow dunes?

A

About 20%

57
Q

What is the soil like at yellow dunes?

A

It is less alkali.

58
Q

What are the plant characteristics?

A
Salt tolerant
Thrive when buried in sand
Leaves are rolled up to reduce moisture loss
Long roots
Rhizomes stabilise the sand
59
Q

What are three example plants that can be found at yellow dunes?

A

Rag wort
Red fescue
Sand sedge

60
Q

What are the main characteristics of grey dunes?

A

Sheltered
More vegetation cover
Little mobile sand
Sand no longer accumulating

61
Q

How much humus is found at grey dunes?

A

Grey dunes have a high humus content.

62
Q

How high are grey dunes?

A

They can reach heights of up to 20m.

63
Q

How much sand is exposed at grey dunes?

A

Less that 10% of the sand is exposed.

64
Q

What type of plant is there less of at grey dunes?

A

There is less marram.

65
Q

What makes grey dunes grey?

A

Surface lichen

66
Q

What are the two key plant characteristics at grey dunes?

A

Higher species diversity

Mainly perennials

67
Q

What are dune slacks?

A

These are depressions in the dunes where the water table is on or near the surface.

68
Q

What causes the depressions in dune slacks?

A

The calm air behind the dunes.

69
Q

What is the soil like at dune slacks?

A

Damp and acidic

70
Q

What are the plants like at dune slacks?

A

Plants that are also found in fresh water wetlands.

71
Q

Give 3 example plants that can be found at dune slacks.

A

Rushes
Phragmite reeds
Big cotton

72
Q

What are the characteristics of Heath/woodlands?

A
The supply of sand is cut off or reduced. 
Well sheltered from winds
Lots of humus
Nutrient rich
Minimal influence by maritime.
73
Q

What is the soil like at heaths and woodlands?

A

It is acidic

74
Q

What are the two plant characteristics?

A

Perennials

Scattered trees

75
Q

Give two example plants that can be found at Heath/ woodlands.

A

Heather

Sea buckthorn

76
Q

What is meant by ridges?

A

These are sequences of dune parallel to the coastline.

77
Q

What are blowouts?

A

These form when fragile sand dunes have their vegetation destroyed by grazing animals such as by rabbits and human activity.

78
Q

What type of human activity can damage sand dunes?

A

Trampling