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35 Cards in this Set
- Front
- Back
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What is succession? |
The process by which an ecosytem changes over time. |
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Name some examples of a new habitat? |
bare volcanic rock, sand |
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What are the initial conditions of a new habitat governed by? |
abiotic variables |
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What is each plant community called? |
a sere |
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What are the initial conditions like? |
dry-no soil to retain water few available minerals high light intensity- no shade from other plants extremes of temperature windy |
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What are the first community in a new habitat? |
pioneer community |
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What are the pioneers of bare rock? |
lichens |
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How are lichens suited to being pioneer species? |
They anchor themselves in cracks and can dissolve bare rock to get minerals. They can withstand long periods. |
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What are the pioneers of of sand dunes? |
marram grass |
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Why is soil important? |
It is able to retain moisture. and slowly release nutrients through decomposition. |
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What happens to lichens when they die? |
decompose to become organic matter (humus). |
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What is the moss sere? |
Mosses and perhaps some grasses can germinate (after the pioneer community-lichens) and grow using the moisture held by the thin soil. AS the mosses and grasses die their decomposition adds to developing soil layer. |
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What is the herbaceous sere made up of? |
small herbaceous (non woody) plants ferns and grasses. |
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How is the herbaceous sere different to pioneer sere? |
They require more water and have good seed dispersal mechanisms. |
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What does it mean if the plants in the herbaceous sere have good seed dispersal mechanism? |
They produce large numbers of small-wind dispersed seeds and germinate rapidly in thin soil. |
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How do taller herbaceous plants make conditions more favourable for the next sere?i |
They reduce wind speed and light intensity helping the soil retain more moisture and the seeds to germinate. |
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Why does the number of mosses and pioneers reduce? |
They are out competed by the herbaceous sere. |
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How is the soil in the shrub sere different? |
It is deeper and contains more humus (decaying matter releasing nutrients) and has a pH closer to neutral than the underlying rock. |
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How do other aboitic factors change in the shrub sere? |
Other abiotic factors such as water availablity, light intensity and wind speed so that more demanding larger shrub plants such as bramble gorse and hawthorn will be able to grow |
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Which sere is the sub-climax community and what do they do? |
The shrub sere. They grow fast so out compete the lower level herbaceous species for light and space. |
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How do woody trees grow/ |
Slowly but when they are established they shade and out compete the shrubs for light and minerals. |
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What does the climax community provide? |
A diverse set of niches to support a large variety of insects and other animal species. |
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What is established in the climax community? |
A complex food web with many trophic levels and interactions |
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What is the climax community usually? |
tree sere |
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What is a climax community? |
Final stable community. |
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What is the order of the seres in first succession? |
pioneer sere moss sere herbaceous plant sere shrub, small tree sere woodland climax sere |
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Why does the animal and plant community become more diverse as time passes? |
There are more niches and greater stability in the range and types of species present. This is because abiotic and biotic variables become less extreme during succession. |
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What is similar everywhere? |
general pattern of primary succession. |
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What do the details of each species found in each area depend on? |
the type of rock, or other subtrate e.g. mud/sand the climate in which the succession is happening. |
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How can you observe succession on the coast? |
With a belt transect from sea further inland. (has to be dunes) |
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What happens when the climax community is removed by humans or destroyed by fire? |
Much of the community of plants might be lost but the pioneers and possibly other plants from primary succession quickly re establish. |
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Why is secondary succession quicker than primary succession? |
there is already well developed soil that possibly contains lots of seeds |
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What is a plagioclimax also known as? |
Deflected succession |
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How do humans stop succession? |
Use animals. The animals graze any plants which would move succession on. |
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What is a plagioclimax? |
Human activity often deliberately stops or reverses a primary succession to maintain an earlier stage of the succession. The human managed community is called a plagioclimax |
