Coastal Sand Dunes

Coastal Systems

Humus

• Rich, dark, organic component of soil

• Forms from the decomposition of dead plant and animal matter

• Provides essential nutrients and improves soil structure, water retention, and fertility

• Acts as a carbon sink

Sand Dune Succession

Stage 1 

• Embryo dune

• Young and very small

• Pioneer species colonise and stabilise the sand 

• Sand accumulates around the newly colonised plant

• These dunes are fragile and tides can easily wash them away

Stage 2 

• Foredune

• Behind the embryo dunes as they build up 

• Marram grass begins to grow, stabilising the dune further

• Species start to become more diverse and cover the ground

Stage 3

• Yellow dune

• Sit above the beach level

• The diversity of organisms increases

• Marram grass incorporate humus, into the dune, creating soil - making the sand/soil more nutrient-rich

Stage 4

• Grey dune

• Have more protection  

• Sand is more protected from the wind and stabilised by vegetation

• Fixed dunes 

• Soil improves

Dune Slack (Stage 5)

• The dip between sand dunes

• Moist or entirely filled with water

• Nutrient-rich and home to a variety of plants and animals 

Stage 6

• Mature dune

• Reaches climax community - final point of a succession that stays unchanged 

• Conditions are much more favourable, with moisture and nutrient-rich soils

• Far above the high-tide level