Succession

A new habitat such as bare soil is populated by pioneer species whose seeds are blown in by the wind

They are adapted to grow in hostile conditions such as high light intensity and fluctuating temperature

• When they are die pioneers are broken down by saprobiotic bacteria increasing the humus and nitrate content of the soil
• The roots stabilise the soil
• The leaves provide shade

• Herbaceous annual plants
• Less hostile environments

• Herbaceous plants out-compete them for light and nutrients 
• Leads to a decline in the population of pioneers and an improvement in soil quality

Woody shrubs and bushes appear as the soil deepens, outcompeting the shrubs and improving soil quality

• Fast growing trees such as birch
• Form a dense forest

• Slower growing larger trees such as oak
• This is called a climax community 
• Nothing can outcompete these trees

• They become less hostile
• This causes the number of niches to increase, enabling a greater variety of plant species to be supported

• Many different plant species can grow
• Consumers have a number of different species to feed on

• The organic matter in soil which provides nitrates and other mineral ions 
• Also retains water in the soil

Moorland would be woodland if it were not for grazing animals, mowing, removing the growing points of woody shrubs and the controlled burning of heather in order to kill saplings

• Lichens, consisting of fungal and algal cells, grow
• Algae produce sugars via photosynthesis and the fungi produce organic acids which break down into mineral ions 
• Eventually enough dead matter accumulates for mosses to grow, then grasses, then succession continues