Sand dunes/plant succession

Question 1

List 3 conditions needed for sand dunes to form?

Answer 1

1. Large tidal range= exposed sand can be dried out and moved by the wind
2. Shallow beach gradient= good conditions for sediment transport
3. Vegetation growth for further growth of dune = an obstacle to trap sand

Question 2

Define the process of plant succession:

Answer 2

• A vegetation succession= a plant community that changes over time
• One community of plants gets replaced by another as succession develops (soil and microclimate is altered)
  -> Eventually, a climatic climax community is reached where the vegetation is in a state of equilibrium with the environment-> no further influx of species
  BUT- human interference e.g. cattle-> climatic climax cannot be reached= plagioclimax (environment is prevented from developing further d2 humans)

Question 3

what are the 5 stages of salt marsh succession

Answer 3

1. Algal stage- blue green algae establishes as they can grow on bare mud-> roots bind
2. Pioneer stage- glasswort grows, roots stabilise mud-> estuarine grows
3. Establishment stage- salt marsh grass grows-> carpet of veg-> salt m increases
4. Stabilization- sea thrift/ scurvy grass grows-> salt rarely is submerged beneath marsh
5. Climax vegetation- red fescue grass grows since salt marsh is sub once or twice a yr

Question 4

when do sand dunes occur/ what are they?

Answer 4

SD occur when prevailing winds blow sediment to the back of a beach-> accumulations of sand shaped into mounds by the wind, represent a dynamic form

Question 5

what are embryo dunes?

Answer 5

upper beach area where sand starts to accumulate around an obstacle

Question 6

what happens at yellow dunes?

Answer 6

sand accumulates and dune grows, veg can develop on upper/back dune surfaces-> stabilising dune

Question 7

what happens at grey dunes?

Answer 7

sand develops into soil with lots of moisture and nutrients-> veg dies= varied plant growth

Question 8

what happens at dune slacks?

Answer 8

water table rises closer to surface/ water is trapped between dunes in storms-> growth of willow grass

Question 9

what happens at heaths and woodlands?

Answer 9

sandy soils develop d2 greater nutrients content, trees e.g. birch grows

Question 10

describe sand dune succession:

Answer 10

1. Embro dunes are first colonised by pioneer plants-> die + release nutrients into sand= increases amount of veg able to grow
2. Embro dunes and their pioneer plants altar the environmental conditions from harsh and salty-> area where plants can survive= new plants colonise
   Marram grass= example of a pioneer plant