Toic 10.3 - Ecological Succession Flashcards
What is primary succession?
Community developing on bare, uncolonised ground
No previous life, vegetation or soil
What is secondary succession?
Community colonisation ground which had been previously colonised whom have been destroyed (eg fire, flood, human activities)
Usually quicker process than primary succession
What are 5 stages of succession? (4 marks)
- Migration, colonisation by Pioneer species
- die and decay, leaving humus, contributing organic matter to form soil
- Creating suitable conditions for other species to establish
- Leading to succession of a species
- Climax community formed (end point), environment now stable
What are seres?
Stages in a complete seral succession
What’s so special about pioneer species?
Can withstand extreme conditions so able to colonise areas
What are pioneer species?
Resilient Organisms that are first to colonize barren environments, adaptive to harsh conditions (extremophiles)
Must be producers (make their own food)
What effect will pioneer species eventually have on the rock?
- eventually penetrate rock surface, break down
- start soil formation
What are examples of pioneer species?
Lichens, then mosses then soils, grasses, weed, shrubs, bushes and eventually trees
How do mosses work as pioneer species?
Grow and die, adding to soil to support growth of grass and weeds
Increasing nutrients in soil (aka forming Humus) for other plants to grow
How is soil formed by pioneer species?
Erosion of rocks, with water and wind, forming soil
Gives opportunities for diverse plants to grow on with increasing humus and nutrients
What is humus?
Dead and decaying (by microorganisms) plants and animals (& faeces)
(Nutrients broken down added to soil)
As the environment changes (abiotic), the species that inhabit it will…
Also change (biotic)
How does succession on sand dunes work? 3 steps
- Pioneer species grow in sand, v v tolerant to lack of water
- Sand accumulates around the plants, it dies and decays
- Humus mixes with sand, forming mini sand dune, allowing bigger plants to grow
Define succession (2 marks)
Sequence of changes in a species (1)
Over a period of time (1)
What is a climax community? 2 marks
The final stage
Of community that are stable, self sustaining
How does colonisation of bare rocks by lichens result in succession over long periods of time? (4 marks)
- they are pioneer species
- erode and break down rocks
- they die and decay, leaving humus
- provide niches for other organisms to grow in
What is mean by ecosystem?
Interactions between organisms and their environment
Explain why the efficiency of energy transfer differs between tropic levels. (3 marks)
- different trophic levels use different proportions of energy
- respiration for movement (heat loss)
- some materials not consumed
- some parts not digested
- released from excretion
Give one reason why the energy transfer from sunlight to the producers is less than 100% efficient. (1 mark)
- light reflected / missed chloroplasts
What is a niche?
environmental factors and interspecies relationships that influence the species.
Where do pioneer species grow?
On newly exposed ground