Lithosere

• • The development of a community of species on bare rock created by a cliff fall, the retreat of a glacier or a volcanic eruption is called a lithosere
  • The initial abiotic conditions are very harsh and unsuitable for most organisms
  • Temperatures are extreme, water availability is severely limited and there is no soil
  • Simple autotrophs such as lichens and algae are the first to colonise the area
• • Conditions improve as dead organic matter and rock fragments gradually accumulate
  • Mosses colonise and a thin layer of soil starts to build up
  • Grasses and ferns then colonise
  • As the layers of soil form and plants get larger, the abiotic factors become less extreme
  • The conditions are never hot or cold or wet or dry as they were at the beginning of the community's development and the development of the soil makes plant nutrients more available
• • Seedlings or less hardy plants can survive under the shade of the larger plants
  • Once pollinating insects become established flowering plants colonise and survive as pollination takes place
• • Once the soil is deep enough and the edaphic factors (soil factors) are suitable, trees can colonise
  • The first tree species to establish usually have wind blown seeds such as birch trees, while the seeds of later species are dispersed by animals for example beech and oak trees
• • In the early stages of development a hydrosere and a lithosere are very different from each other
  • This is due to their different original conditions
  • However as succession occurs these differences are reduced and the final communities are very similar to each other because they are controlled by the climate of the region which is the same for both communities