Biosphere : Sand Dune Succession

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Biosphere : Sand Dune Succession

  1. 1. Higher Geography Pupil Conference Dalkeith HS 23 rd March 2007 BIOSPHERE Val Vannet High School of Dundee
  2. 2. The Biosphere Sand Dune Succession
  3. 3. Plant Succession <ul><li>Evolution of plant communities </li></ul><ul><li>From pioneer species to climax vegetation </li></ul><ul><li>Related to change in the environment </li></ul><ul><li>Change brought about by the plants themselves </li></ul><ul><li>This change then favours new species </li></ul><ul><li>‘ Plants are the architects of their own demise’ </li></ul>
  4. 4. Sand Dune Systems <ul><li>Conditions </li></ul><ul><li>Supply of sand </li></ul><ul><li>On-shore winds </li></ul><ul><li>Colonising plants </li></ul><ul><li>Processes </li></ul><ul><li>Sand blown landwards </li></ul><ul><li>Sand trapped by plants </li></ul><ul><li>Plant growth assists dunes to grow </li></ul><ul><li>Process repeated on seaward side </li></ul><ul><li>Older dunes stop growing </li></ul><ul><li>System grows seawards </li></ul>
  5. 5. Tentsmuir :W W2 shore defence These tank traps were at the high water mark in 1940
  6. 6. Seaward growth of the sand dunes at Tentsmuir since 1940
  7. 7. Sample sand dune systems
  8. 8. Tentsmuir
  9. 9. Buddon Ness
  10. 10. St Cyrus
  11. 11. Forvie
  12. 12. Culbin sands
  13. 13. Sand Dune Transect
  14. 14. The Foreshore Blowing sand Salty Dry
  15. 15. Saltwort Fleshy leaves store water Deep tap roots Low growing
  16. 16. Sandwort Waxy leaves
  17. 17. Sea Rocket Fleshy, waxy leaves Tap roots
  18. 18. Frosted orache ‘ Mealy’ leaves are salt repellant Long tap roots
  19. 19. Couch grass Leaves prostrate Withstands modest burial Tolerates salt
  20. 20. Saltwort Frosted orache Couch Grass
  21. 21. Embryo Dunes Scattered foreshore plants Seaweed (humus) On shore winds Sand builds up Highest tide line
  22. 22. Level of built-up sand
  23. 23. Frosted orache Embryo dune
  24. 24. Foredunes Couch grass (salt tolerant) Lyme grass (salt tolerant)
  25. 25. Mobile (yellow) dunes Marram grass
  26. 26. Marram grass <ul><li>Cannot tolerate salt </li></ul><ul><li>‘ Thrives’ on being buried by sand </li></ul><ul><li>Inrolled leaves </li></ul><ul><li>Long tap roots </li></ul><ul><li>Underground rhizomes stabilise dunes </li></ul>
  27. 27. Much bare sand hence ‘yellow’
  28. 28. Ragwort Marram
  29. 29. <ul><li>Less bare sand </li></ul><ul><li>More humus </li></ul><ul><li>Lower pH </li></ul><ul><li>Less Marram </li></ul><ul><li>More ‘competitors’ </li></ul>
  30. 30. Fixed (grey) dunes Marram more sparse and weaker Other species dominate
  31. 31. Increasing floristic diversity Harebells Bedstraw Restharrow
  32. 32. Parasol mushrooms More humus and soil moisture
  33. 33. Why ‘grey’? Lichens
  34. 34. Marram now very sparse Ground cover almost complete
  35. 35. Dune slacks Main dune ridge Lower relief intersects water table
  36. 36. Phragmites reeds
  37. 37. Rushes
  38. 38. Seasonal slack Rushes Creeping willow
  39. 39. Main dune ridge Slack Dune heath Cotton grass
  40. 40. Final stages of succession Alkaline shell sand Grassland Heathland Acid mineral sand
  41. 41. Dune Scrub (often spinous!) Gorse Buckthorn Dog rose
  42. 42. Sea Buckthorn is well named!
  43. 43. Mixed Woodland Climax
  44. 44. Vegetation Surveys <ul><li>Transect lines </li></ul><ul><li>Ranging rods </li></ul><ul><li>Tape measure </li></ul><ul><li>Clinometer to measure angle of slope </li></ul>
  45. 45. Vegetation Surveys <ul><li>Quadrats </li></ul><ul><li>% occurrence recorded </li></ul>
  46. 46. Easy ! 100% Marram
  47. 47. Minimum Need-to-Know! <ul><li>Definition of succession </li></ul><ul><li>Definition of climax vegetation </li></ul><ul><li>Stages of the succession on sand dunes </li></ul><ul><li>One or two named plants for each stage </li></ul><ul><li>How are these plants adapted to the environment? </li></ul>

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