Sand dunes Flashcards
What are the inputs in a sand dune system
- prevailing onshore wind - saltation and surface creep
- Large tidal range - dries the land
- starting vegetation - marram grass
What else is essential for the dune development to begin
-Strand Line
What is ecological succession
-Ecological succession is the process of change in the species structure of an ecological community over time.
What is a pioneer species
-The first plant to colonize an area - special adaptions
What is a climatic climax community
-the vegetation that would evolve in a climate region if the progression is not interrupted
What is a psammosere
-succession of san due - a sequence of the sand dune progression
What is saltation
-sand bounce with wind
What is the succession of dunes
- Embryo
- Fore/yellow dunes
- Grey/foxed dunes
- Wasting dunes
- Climax
What is in between mobile and fixed dunes
-Dune slack
What happens at the embryo dunes
- Sand from saltation gets trapped by obstacles (seaweed, rock, driftwood, litter) at the back of the beach, possibly on the highest berm or storm beach
- The first dunes to develop are known as embryo dunes. They allow pioneer species to grow
- This stabilizes the surface
- The plants add organic matter to the dunes
What are the characteristics at the embryo dune
- less than 1% humus
- 1m high
- 80% exposed to sand
- low water table
- sea rocket and couch grass
- 8.5ph
What happens at the fore/yellow dunes
- They are mobile dunes - initially yellow because they contain little organic matter, but as vegetation increases, hummus is added back into the sand
- There are species such as marram grass
What are the characteristics at the fore/yellow dune
- 5m high
- 20% exposed to sand
- Low water table
- yellow soil
- humus 2.5%
- 7.5ph
What is a dune slack
- a dip between mobile dune 6-8m deep
- it is below the water table
- has aquatic plants
What is grey dune
- fixed dune
- grey soil
- 10m high
- less than 10% exposed to sand
- 10% humus
- shrubs - heather/brambles
