Sefton Dunes

Question 1

Sand dunes definition

Answer 1

mounds or ridges of dredged sand

Question 2

where do sand dunes form?

Answer 2

coast and inland areas where there is sufficient sand and wind

Question 3

sefton dunes cover how many km along irish sea coast?

Answer 3

17km

Question 4

characteristics of embryo dunes

Answer 4

• few cm high
• sparse covering of sand couch grass (covers 25%) pioneer species
• sand couch can extract fresh water from saltwater
• sand is alkaline due to sea water and shells

Question 5

fore dune characterisitics

Answer 5

• rises 2m above shoreline
• less exposed than embryo dunes
• salt water inclusion is less of a problem
• sand couch grass and marram grass dominate (40% still sand)

Question 6

yellow dune characteristics

Answer 6

• rise nearly 20m above beach
• size shows its effectiveness of vegetation trapping wind blown sand
• marram grass is dominant species, couch grass has disappeared
• other species are sea holly, thistles and lady’s bedstraw
• marram grass is a xerophyte ( needs little water)

Question 7

characteristics of dune slacks

Answer 7

• depressions between the dune ridges create a different physical environment
• water table is at/near the surface
• excess water is a problem rather than drought
• specialised plants adapt to the wet, aquatic conditions e.g. creeping willow, rushes and flag iris
• these colonise the dune slacks, creating a freshwater hydrosere

Question 8

fixed dunes characteristics

Answer 8

• older dunes 200m away from shoreline
• complete vegetation cover and fixed position
• more sheltered and support thin but well developed soils that provide mineral nutrients and moisture for plants
• net primary productivity and biodiversity are higher and richer nutrient cycle
• winds much lighter=less blown sand
• organic plant material mixes with sand to form a shallow soil that is neutral or slightly acidic
• soil is both a store of mineral nutrients and moisture
• specialised xerophytes e.g sea spurge, but wide range of species e.g. bloody cranesbill, round wintergreen
• more common species e.g. dandelion, daisies, pansies
• further inland woody plants e.g. heather, sea buckthorn and hawthorn
• under natural conditions, vegetation on oldest dunes are mixed oak-birch woodland. however at sefton, replaced with scots pine