SuccessionSuccession is a directional change in a community of organisms over time.
1) Pioneer community; Algae and lichens begin to live on the bare rock. 2) Erosion of the rock, and a build-up of dead and rotting organisms, produces enough soil for larger plants like mosses and ferns to grow. These succeed the algae and lichens.3) Larger plants succeed these smaller plants until a final stable community is reached. This is the climax community. Often woodland communities.
Sand dunes example-1) pioneer plants like sea rocket colonise the sand. These can tolerate salt water spray and lack of fresh water and unstable sand. 2) Wind-blown sand build up around the base of these plants forming a mini sand dune. Plants die and decay and nutrients build up. As the dune gets bigger, larger plants like sea sandwort and sea couch grass colonise it. Sea couch grass has underground stems that help to stabilise the sand. 3) More stability= more accumulation of nutrients, plants like sea spurge and Marram grass start to grow. Marram Grass is special; its shoots trap wind-blow sand and as the sand accumulates, the shoots grow taller to stay above the growing dune. Trapping more sand. 4) As the sand dunes and nutrients build up, other plants begin to colonise the dunes. Such as hare's foot clover and bird's food trefoil which are members of the legume family. Bacteria in their root nodules convert nitrogen into nitrates. Nitrates available so more species colonise stabilising them further.