Lithosere

• Lithosere succession starts on bare rock formed by a volcanic eruption, meteorites or melting ice sheets
• The pioneer species is lichen because they have a huge range of tolerance and can survive the extreme abiotic factors e.g very low water availability, very high light intensity and no soil
• The lichens grow, reproduce and die, and the dead organic matter is decomposed into humus then soil. Water stays in the soil for longer and there are more nutrients for plants.

  grasses can take root and grow, as well as moss. They outcompete the lichen for light. There is now habitat for insects to survive in so the biodiversity increases.
• Over time the soil builds up more, so they are more nutrients and water in the soil. Shrubs begin to grow, which outcompete the grasses so the niche is replaced. There is more food and shelter available for insects, birds and mammals so the biodiversity increases.
• The soil continues building up until it is deep enough for trees to take root. Trees have large roots that need deep soil and lots of nutrients. As the trees start to grow bigger the biodiversity increases as there is more shelter and food available, but as the trees form a solid canopy any shrubs on the ground cannot survive as there is no light.

  This is a climax community.
• Climax community conditions due to trees:

  • wind decreases because there are more vegetation making more wind barriers
  • temperature decreases at peak daylight because the tree canopy cools the area. The temperature increases at night because the canopies insulate the ground underneath it. Overall trees prevent temperature extremes.
  • the biodiversity increases until a developed canopy forest where it decreases and then stabilises due to decreased light availability
• How factors change through the seres:

  • soil - increases in volume and depth - there is increased fertility
  • water availability - increases due to dead organic matter storing it in the soil, evapotranspiration and interception
  • wind - decreases due to more vegetation forming more wind barriers
  • temperature - extremes are prevented by the insulating canopy
  • biodiversity - increases until a developed fires where it decreases and stabilises due to light levels