2B.3C

Question 1

How is vegetation important in stabilising sandy coastlines

Answer 1

Vegetation is important in stabilising sandy coastlines through dune successional development on sandy coastlines and salt marsh successional development in estuarine areas

Question 2

How does vegeation generally protetc from erosion

Answer 2

• Plant roots bind sediment together, making it harder to erode.
• Plant stems and leaves covering the ground surface protect sediment from wave erosion and erosion form tidal or longshore currents when exposed at high tide.
• They also prevent sediment from wind erosion at low tide.

Question 3

Why is the coast a harsh environment for plants?

Answer 3

• They’re exposed to high wind speeds at low tide.
• Lack of shade produces a high diurnal (daily) temperature range.
• They’re submerged in salty water for half the day.
• The evaporated sea spray makes the sediment saline.
• Salt is highly porous and permeable, so rain water drains quickly- so plants have little fresh water.
• Submerged sediment has its pores saturated with salt water - there’s no oxygen for plant roots to respire with.
• Sand lacks nutrients

Question 4

What are pioneer plants and what are their roles

Answer 4

These are the first plants to colonise freshly deposited sediment. They modify the environment:
1) Stabilising sediment
2) Adding organic matter that retains moisture, contributes nutrients and provides shade.
3) Reduce evaporation in sand.

Question 5

How do pioneer plants help other plants grow

Answer 5

• Now, slightly less hardy plants can colonise the sediment. They add more organic matter, stabilise existing sediment and trap more.
• Each step in plant succession is called a seral stage.
• The end result of plant succession is called a (climatic) climax community.

Question 6

Give two definitons of plant succession

Answer 6

1) the changing structure of a plant community over time as an area of initially bare sediment is colonised.
2) the process by which a series of different plant communities occupy an area over time

Question 7

Define xerophytic and psammosere

Answer 7

• Xerophytic plants are specially adapted to dry conditions to colonise bare sand.
• Plant succession on sand is called psammosere

Question 8

Explain plant succession

Answer 8

​1) Embryo dunes form when seaweed driftwood or litter provides a barrier or shelter to trap sand.
2) As the embryo grows, it is colonised by xerophytic pioneer plants, like sea couch grass, lyme grass, saltwort and sea rocket.
3) Pioneer plants stabilise the sand allowing marram grass to colonise.
4) As the marram grass and sedge grass dies, it adds hummus to the sand, creating soil. A grey dune develops, with plants such as gorse
5) The dune is now above high tide level, so rain washes salt from the soil, making it less saline.
6) The soil now has improved nutrients and moisture retention, allowing non-xerophytic plants to colonise the dunes until a climax plant community is reached, in equilibrium with the climate and soil conditions.

Question 9

What are the fatures of marram grass

Answer 9

1) has waxy leaves to limit water loss through transpiration and resist wind-blown sand abrasion.
2) has roots that can grow to 3m to reach down the water table and the stem can grow 1m a year to avoid burial by deposited sand.
3) allows the dune to grow, rapidly forming a yellow dune

Question 10

What are halophytic plants and what is the halosere

Answer 10

• Halophytic plants are specially adapted to saline conditions to colonise mud.
• Halosere is plant succession in salty water

Question 11

Why are estuarine areas ideal for salt marshes

Answer 11

• they’re sheltered from strong waves (so sediment like mud and silt can be deposited)
  -rivers transport a supply of sediment to the river mouth, which may be added to by sediment flowing into the estuary at high tide

Question 12

Define flocculation

Answer 12

The mixing of fresh water and sea water in the estuary causes clay particles to stick together and sink

Question 13

Describe halosere

Answer 13

• The mixing of fresh water and sea water in the estuary causes clay particles to stick together and sink - called flocculation.
• Blue-green algae and gut weed colonise mud, exposed at low tide for only a few hours.
• The algae binds mud, adds organic matter, and traps sediment.
• As the sediment thickens, water depth is reduced, and the mud is covered by tide for less time.
• Halophytic glasswort and cord grass colonise as the next seral stage - the marsh is still low, and covered by high tide each day.
• An accumulation of organic matter and sediment raises the height of the marsh until it is only covered by spring tides.
• The higher marsh is colonised by less hardy plants
  -Rainwater washes salt out of the high marsh’s soil, allowing land plants to colonise.
• This continues until climax community is reached.