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29 Cards in this Set
- Front
- Back
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What is succession? |
Process by which an ecosystem changes over time. Consists of a series of events and leads to climax community. |
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What are the two types of succession? |
Primary succession Secondary succession |
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In what circumstances does primary succession occur? |
Bare rock No soil |
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When does secondary succession occur? |
Land which has been cleared off plants but the soil remains
E.g. after forest fire |
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What's are the stages of primary Succession? |
•Pioneer species grow in extreme conditions •They die and are decomposed to form humus; basic soil; more minerals •Less hostile: water to be retained. •Larger organism can be supported, these succeed pioneer species •They die and decompose, more and more organic material piles up •Soil becomes rich with mineral ions |
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As more and more plants grow in an area, what else starts happening? |
More animals move in |
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What are the Pioneer species in primary succession likely to be? |
Algae and Lichens |
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What happens in secondary succession? |
Bigger pioneer species begin to grow since there is already a soil layer |
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What happens to the dominant species during succession? |
They get out competed by plants and animals which are better adapted to the Improved conditions and then they become the dominant species |
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What happens to species diversity and abundance as succession goes on? |
Increases |
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What happens to the biomass as succession carries on? |
Increases as inhabiting plants and animals are larger (and denser for plants) |
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What is a climax community? |
The final stage of succession The ecosystem is in a steady state
The ecosystem is supporting the largest and most complex community of organisms it can |
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Are the climax community for all ecosystems the same? |
No |
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What is climatic climax? |
Climax community which depends on the climate of the ecosystem |
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How can humans affect Succession? How? |
They can prevent succession by stopping climax community from developing or deflect it
Grazing Mowing Burning |
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Why is deadwood left to decay in forests? Why is this good for the forest? |
Releases mineral ions, nitrogenous compounds
Forms humus
Stabilizes soil
Releases CO2 from fungal respiration |
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How to sample a large area? For distribution and abundance? |
Mark appropriate size grid Line transect Repeat the line transect Use quadrants, appropriate size Identify species usesing keys % of species frequency Kite diagram it or spearmans rank |
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Why do we need carbon? |
To make organic materials; macromolecules Growth and repair |
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Why are abiotic conditions in newly formed/ exposed land harsh? |
No soil to retain water |
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What do pioneer species do? |
Stabilise environment. Change pH of soil. Make land slightly make habitable |
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What is a climax community that has artificially stopped from being developed called? |
Plagioclimax |
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How does mowing the grass deflect succession? |
The growing point of woody plants are cut off constantly so larger plants can't establish themselves since only the grass can survive being mowed. The grassy field has therefore reached its climax community |
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How do you on I'd succession has been deflected in a grassy field? |
Because it's not in its natural stage, there should also be flowering plants etc... |
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What two other things has the same effect as mowing? |
Grazing Burning |
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How do pioneer species arrive at bare rock? |
•Spores for lichens and mosses •Seeds through bird faeces; widely dispersed |
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Characteristics of pioneer species |
Asexual reproduction Photosynthesis Tolerance for extremes |
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Why can water be retained? |
Erosion of rock and build up of soil |
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What anaerobic conditions determine what species of plant grows in an area? |
Mineral content pH Water depth |
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Pioneer vs climax community |
•Pioneers arrive before climax •Pioneer community has lower biodiversity •Pioneer community has lower biomass •Pioneer community is often less stable |
