4. Succession Flashcards
Define succession
Process in which an ecosystem changes over time - Natural process as environment and animals change
What is succession
Eco systems dynamic
Succession happens in stages at each stage the plants and animal communities in area are slowly changed and this changes the environmental conditions which makes environment suitable for more species with different adaptations
Biotic conditions change as the abiotic conditions change - one community of organisms to be succeeded by another
What are the 2 main types of succession
Primary
Secondary
What is primary succession
Happens on land that’s been nearly formed or exposed
Eg when volcano has erupted to form new rock surface or where sea level has dropped exposing new area or lane
No soil or organic material here - just hate rock
What species does pinoneer succession start with ?
They start when species colonise new land surface.
Seeds / spores blown in by wind and grow
First species to colonise area are pioneer species
Abiotic conditions are harsh so pioneer species only grow as adapted
Example
Hostile abiotic conditions
Limited water available because soil has no water retention
Few minerals / nutrients as no soil
Exposure to wind / rain
Fluctuating temps
Example
Pioneer species
Marram grass - sandunes/ deep roots to get water and tolerate salty environment
Lichens - fungus/ rocky conditions as fungus secrete acids which erode rock releasing minerals
What happens when the pioneer species die ?
They change the abiotic conditions as they die the microorganisms decompose the dead organic material forming basic soil
^ making less hostile conditions as soil helps retain water so new organisms can now grow - these organism then die& decay adding more organic material which makes soil deeper& richer
What does nitrogen fixing bacteria do ?
Turns nitrogen from atmosphere into ammonia which is used by plants
So larger / comped plants like shrubs can grow
Biomass definition
Mass of living material in an ecosystem
What do the dominant species do ?
They out compete the species and plants already there
Cause most change to the abiotic environment making it more suitable for other species
What happens to environment as succession goes on and on ?
Ecosystem more complex as more species move in alongside existing species
Plants create more habitats and act as food source for organisms
Biodiversity AND biomass increases
Abiotic conditions less hostile
What is climax community
Ecosystem supporting the largest most complex community of plants and animals it can
Won’t change much more after this
Steady state
What do trees do in evosystemt ?
Reduce light available to shorter plants
Help stabilise fluctuating temps
Increase air humidity
Provide shade
Reduce wind
All moderate temp
What is secondary succession ?
When the land that’s been cleared at all plants but the soil remains
After forest fire or deforestation
The community of species is destroyed but without too much disturbance to soil
