Vegetation Succession Sand Dunes Plant Succession Evolution of

Vegetation Succession Sand Dunes

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’

Sand Dune Transect

The Foreshore Salty Blowing sand Dry

Saltwort Fleshy leaves store water Low growing Deep tap roots

Sandwort Waxy leaves

Sea Rocket Fleshy, waxy leaves Tap roots

Frosted orache Long tap roots ‘Mealy’ leaves are salt repellant

Couch grass Withstands modest burial Leaves prostrate Tolerates salt

Frosted orache Saltwort Couch Grass

Embryo Dunes Highest tide line Scattered foreshore plants On shore winds Seaweed (humus) Sand builds up

Level of built-up sand

Embryo dune Frosted orache

Foredunes Lyme grass (salt tolerant) Couch grass (salt tolerant)

Mobile (yellow) dunes Marram grass

Marram grass • Cannot tolerate salt • ‘Thrives’ on being buried by sand • Inrolled leaves • Long tap roots • Underground rhizomes stabilise dunes

Much bare sand hence ‘yellow’

Ragwort Marram

• • • Less bare sand More humus Lower p. H Less Marram More ‘competitors’

Fixed (grey) dunes Other species dominate Marram more sparse and weaker

Increasing floristic diversity Harebells Bedstraw Restharrow

Parasol mushrooms More humus and soil moisture

Why ‘grey’? Lichens

Marram now very sparse Ground cover almost complete

Dune slacks Lower relief intersects water table Main dune ridge

Phragmites reeds

Rushes

Seasonal slack Creeping willow Rushes

Main dune ridge Slack Dune heath Cotton grass

Final stages of succession Grassland Alkaline shell sand Acid mineral sand Heathland

Dune Scrub (often spinous!) Buckthorn Dog rose Gorse

Mixed Woodland Climax Man’s activities usually prevents this from developing

Back on the foreshore…. . New embryo dunes are forming….