Succession Flashcards
What is succession?
the process by which ecosystems change over time
What are the two types of succession?
primary and secondary
Where does primary succession occur?
occurs in area of land that has been newly formed or exposed such as bare rock, there is no soil present
Where does secondary succession occur?
occurs in areas of land where soil is present, but it contains no plant or animal species. e.g. after a forest fire
When would primary succession occur?
after a volcanic eruption, sand is blown by wind to create new sand dunes, silt and mud is deposited at rivers, glaciers retreat exposing rock
What are the main stages of succession?
pioneer community, intermediate community and climax community
Which stage of succession has the greatest biodiversity?
intermediate community
What happens in the first stage of primary succession?
a pioneer species colonises an inhospitable environment, generally a spore or seed carried in the wind
What are some adaptations of the pioneer species that enable them to colonise the bare environment?
ability to produce large quantities of seeds or spores, seeds that germinate rapidly, ability to photosynthesise, tolerance to extreme environments, ability to fix nitrogen from atmosphere
What is humus?
the organic component of soil created through decomposition of pioneer species
How is the basis of soil created?
weathering of rock and decomposition of pioneer species
What is the climax community?
the stable state which shows little change over time as a few species dominate the ecosystem
What is deflected succession?
human activities halt the natural flow of succession and prevent ecosystem reaching the climax community
What is the final stage of an ecosystem if succession is deflected?
plagioclimax
What are some examples of deflected succession occurring?
grazing or trampling by animals, planting crops, burning to clear forest areas
