Psammosere (Dune Succession)

Refers to AQA A2 Geography

Ecosystems: Change and Challenge Option

HideShow resource information
View mindmap
  • Psammosere (Dune Succession)
    • What is a vegetation succession?
      • The evolution of plant communities over time from pioneer species to climax vegetation
      • At each stage of the plant succession, the plant community alters the soil and micro-climate, allowing other species to establish
      • One community of plants is replaced by another as a succession begins to develop
        • Pioneer species out competed by plants better adapted to new conditions
      • Unless there is human involvement, a climatic climax is reached, where vegetation is in equilibrium with the environment and there are no new species
    • Psammoseres
      • 5000 ha of partially vegetated sand dunes in Scotland alone
        • 500 + vegetation types
        • Plants which grow have to adapt to an environment which is dry, salty, mobile and nutrient-poor.
    • Requirements for the development of a sand dune
      • Plentiful supply of sand
      • Strong winds to transport sand particles through saltation
      • An obstacle such as a plant to trap the sand
        • Why plants are essential to the formation and growth of sand dunes.
    • Pioneer Stage
      • Seeds blown in by wind or washed in by the sea
      • Poor rooting conditions due to drought, strong winds, water immersion and alkaline conditions created by crushed sea shells.
      • Wind moves the sand in the dunes, allowing water to drain through rapidly.
    • Building Stage
      • Plants trap sand as they grow, binding sand together with their roots
      • Humus is created by decaying pioneer plants creating more fertile growing conditions. The soil also becomes less alkaline as pioneer plants grow and trap rainwater.
      • Less hardy plants can now grow and begin to shade out the pioneers
      • As plants colonise, the dunes chage colour from yellow to grey as the sand disappears
    • Climax Stage
      • Taller plants such as trees and more complex plant species such as moorland heather can now grow
      • Plants from earlier stages die out due to compotion for water/ light
      • When the water table reaches, or nearly reaches, the surface, dune slacks can occur. Here, water tolerant plants grow.
    • Dunes Develop Inland
      • New dunes develop on the fore shore (in pioneer stage)
      • On older, more sheltered dunes the psammosere is in its building phase
      • Furthest inland, on the oldest dunes, the climax stage will be reached
    • Embreyo and Fore Dunes
      • Plants with waxy leaves to withstand water and wind
      • Low plants to avoid strong winds
      • Deep tap roots to gain all available water
      • High salt tolerance
      • e.g. SAND WORT, SEA COUCH
    • Yellow Dunes
      • Dominant marram grass
        • trives on being buried by sand
        • In rolled leaves to reduce moisture loss
        • Underground rhizomes stabablise sand.
    • Grey Dunes
      • High species diversity, mainly perennials, surface lichens give grey appearance, sparse marram,


No comments have yet been made

Similar Geography resources:

See all Geography resources »See all Ecosystems and biodiversity under threat resources »