Succession - B12 Flashcards
What is succession?
Succession is the process by which a community changes over time, due to environmental change due to the species present
What happens at each stage in succession?
At each stage, the plant and animal communities in an area slowly change the environmental conditions. These changes produce conditions suitable for other species with different adaptations.
Where does primary succession occur?
On land that’s newly formed or exposed(e.g. where a volcano has erupted and formed a new rock surface -there’s no soil or organic material to start with)
When does the pioneer stage of succession begin?
Starts when species colonise a new land surface. Seeds and spores are blown in by the wind and begin to grow.
What is the name of the first species in the pioneer stage of succession?
The first species to grow are called pioneer species, which are especially adapted to cope with abiotic conditions.
True or false: abiotic factors are hostile
true
What are some examples of pioneer species?
marram grass - found on sand dunes, has deep roots to reach water and can tolerate salty environments
lichens - fungus - secretes acids which erode the rock, releasing minerals
some shrubs -pioneer species which can tolerate drought
What are some examples of hostile conditions?
limited water as little soil to retain water, few minerals or nutrients as there is no soil, high light intensity, exposed to wind and rain, fluctuating temperatures as the area is exposed to direct sun and the elements.
How do pioneer species change abiotic conditions?
They die and microorganisms decompose the dead organic material(humus), which forms basic soil. This causes soil to become less hostile(e.g. basic soil helps retain water and minerals). This allows new species with different adaptations to move in and grow. This cycle repeats again.
How may an environment become less suitable for a previous species?
Some new species change the environment so that it is less suitable
What happens at each stage of succession?
Plants and animals which are better adapted for the improved conditions move in, out-compete the previous organisms and become the dominant species in the ecosystem.
What are dominant species?
the dominant species are the ones which cause most change to the abiotic environment
How does an ecosystem become more complex?
The ecosystem becomes more complex as new species move in alongside previous species causing biodiversity to increase. Plants create habitats for animals and produce less hostile environments and increase the amount of biomass.
What is a climax community?
Changes result in a climax community - a stable community with no further succession. The ecosystem will not change much more - it’s in a steady state. Some species present for long periods of time. Abiotic factors are constant. The population size is stable.
What are some factors that limit the populations in a climax community?
availability of nutrients(e.g. nitrates in soil) no.s of producers providing energy to the food web, light intensity affecting the rate of photosynthesis, disease killing weaker members of the populations, niches available/ space for building nests, competition(inter/intra specific) for resources such as food/light/mineral ions/territory/ mates etc.
