AQA Geography A2 Ecosystems Case Studies Part 1

Psammosere succession

In the Psammosere succession there is movement of sand due to the wind blowing the sand inland, this can then build up around an obstacle to then accumulate and form a dune. There are many seres in this progression and each one is named after the type of dune which it is located:

Embryo Dune

This is where sand starts to accumulate as plants which are mainly Marram grass which are able to survive the hostile environment with high amount of salt, droughts, strong winds and acidic. It stabilises the dune so it able to increase in size.

Fore Dune

These form as more sands builds up on the dunes also embryo dunes join together to form a bigger dune. It is not as hostile so plants like Sea Rocket start to grow. But Marram grass is still dominated in this stage.

Yellow dune

As the dune continues to develop sand builds up. But as plants die they start to form soil, although these are “yellow” because of the lack of soil. Conditions become better as further away from the sea. Plants cover 50-80% of the dune, Marram grass is still dominated but other plants can grow in sheltered hollows such as the Sea Spurge.

Grey dune

As the Marram grass dies soil starts to form and there is a layer of humus so more plants can grow here also as it is less acidic and more sheltered from the wind, this means plants like Gorse can start to dominate.

Dune Slack

This is where there is a depression between the dunes where it is below the water table so it can fill up with water. Conditions here tend to be more favourable due to the sheltered conditions so a more developed community forms which are water loving plants such as Reeds are dominate.

Mature dune

The final stage of a dune this is where the dune no longer gets a fresh supply of sand as it is too far away from the beach. This is where a mature woodland forms, the dominate species on this type of dune is Oak tree (Below). A forest forms and depending on the local climate depends on what type of forest forms such as deciduous forest.

Interference of a progression:

Human interference: people keep beaches aesthetically pleasing stop dunes forming.

Tourism: People walking over the dunes and displace vegetation and sediment

Intense weather: strong winds or heavy rain could wash or blow away sediment.

Example of a Psammosere

Magillian beach, North Western corner of Northern Ireland. The beach formed due changes in the sea level in the last ice age and is Irelands biggest known coastal accumulation feature.

Biome

These are major world scale ecosystems each with its own climatic climax vegetation spread across and area the size of continents.

There are 6 major biomes these are:

·         Tropical rainforest

·         Temperate forest

·         Desert

·         Grassland/ savannah

·         Taiga

·         Tundra

They are distributed from the equator and are distributed…