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Vegetation Succession
Sand Dunes
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Plant Succession Evolution of plant communities
From pioneer species to climax vegetation Related to change in the environment Change brought about by the plants themselves This change then favours new species ‘Plants are the architects of their own demise’
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Sand Dune Transect
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The Foreshore Salty Blowing sand Dry
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Saltwort Fleshy leaves store water Low growing Deep tap roots
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Sandwort Waxy leaves
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Sea Rocket Fleshy, waxy leaves Tap roots
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Frosted orache Long tap roots ‘Mealy’ leaves are salt repellant
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Couch grass Withstands modest burial Leaves prostrate Tolerates salt
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Saltwort Frosted orache Couch Grass
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Embryo Dunes Highest tide line On shore winds
Scattered foreshore plants Seaweed (humus) Sand builds up
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Level of built-up sand
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Embryo dune Frosted orache
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Foredunes Lyme grass (salt tolerant) Couch grass (salt tolerant)
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Mobile (yellow) dunes Marram grass
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Marram grass Cannot tolerate salt ‘Thrives’ on being buried by sand
Inrolled leaves Long tap roots Underground rhizomes stabilise dunes
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Much bare sand hence ‘yellow’
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Ragwort Marram
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Less bare sand More humus Lower pH Less Marram More ‘competitors’
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Fixed (grey) dunes Other species dominate
Marram more sparse and weaker
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Increasing floristic diversity
Harebells Restharrow Bedstraw
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Parasol mushrooms More humus and soil moisture
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Why ‘grey’? Lichens
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Marram now very sparse Ground cover almost complete
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Dune slacks Lower relief intersects water table Main dune ridge
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Phragmites reeds
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Rushes
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Seasonal slack Creeping willow Rushes
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Main dune ridge Slack Cotton grass Dune heath
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Final stages of succession
Grassland Heathland Alkaline shell sand Acid mineral sand
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Dune Scrub (often spinous!)
Buckthorn Dog rose Gorse
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Man’s activities usually prevents this from developing
Mixed Woodland Climax Man’s activities usually prevents this from developing
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Back on the foreshore….. New embryo dunes are forming….
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