succession Flashcards
what is meant by ‘succession’?
long time directional change from bare inorganic surfaces to plant communities to a climax community over time
how does succession change ecosystems?
changes in abiotic factors change the plants and animals present
what is meant by ‘sere’?
a stage of change
what is primary succession?
formation/exposure of land
- no soil or organic material
- slow process
e.g. volcanoes erupting/glaciers retreating
what is secondary succession?
soil present
- rapid process
- no plant/animal species
what is the first seral stage?
pioneers
- often lichen/algae
- highly adapted: germinate rapidly, photosynthesise, tolerate extreme environments, can fix nitrogen from soil
- spores / seeds carried by wind
what is the second seral stage?
intermediate
- rock surface weathers
- pioneers die and are released as humus
- organic material is formed
what are secondary colonisers?
mosses
- sometimes animals can colonise
what are tertiary colonisers?
grasses
- can survive in conditions without abundance of water
- adapted to reduce water loss
what is scrubland?
shrubs and small trees
what is the third seral stage?
climax
- very stable
- dependant on environment
- often a dominant species
what is deflected succession / plagioclimax?
succession stopped artificially
e.g. grazing, removal of vegetation to plant crops, burning for forest clearance
what is the difference between primary and secondary succession?
primary succession occurs on bare rock/sand without soil whereas secondary succession takes place where soil is present but the area contains no plants or animals
what is the collective name of plant and animal species that are present at the end of primary succession?
climax community
