Geography-Biosphere-Sand dune succession
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Plant cover increases –
- the amount of sand showing through the dune decreases as more of the ground is covered by vegetation.
- Little cover in the pioneer stage, more in the building stage and complete cover in the climax stage unless disturbed by animals/humans/storms etc.
• Soil moisture increases –
- rain/fresh water is trapped with added humus/plant cover and longer rooted plants drawing water up from the water table.
- Xerophytic plants found in the drier strandline and embryo dune
- On the yellow dune Marram grass has long rhizomes to spread through the sand.
- Dune slacks at or near the water table
- have hydrophytic species like reeds, rushes and flag iris.
• Organic matter content increases
- – decaying pioneer species adding humus to the sand.
- In the fore-dune more plants stabilise the sand adding humus changing the sand to a sandy loam and from the sandy colour of this and the yellow dune to the grey dune.
• PH decreases –
- shells (CaCO3) producing alkaline conditions on shore, more neutral pH by the climax stage as plants decay and add acid to the soil.
- . In the climax stage a range of plants from heathers to birch, pine or oak woodland can grow depending on the final pH value of the soil.
• Salinity decreases –
Increased distance from the sea and salt water/tides/spray increases the amount and variety of plant species that can cope with the conditions.
Plants on embryo and fore dunes
- Sea ricket
- Lyme grass
- Wavy hair grass
- Sea buckthorn
- cotton grass
- Flag iris
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