Succession Flashcards
Succession
The changes that occur in a community in an area overtime due to changes in abiotic factors + changes in species present
How different pre existing species in the community colonise an area over time
Primary succession
The changes that occur in a community in an area overtime due to changes in abiotic factors + changes in species present
SPECIFICALLY WHERE THERE WAS NO LIFE BEFORE AND NO PRE EXISTING SOIL
Examples of primary succession
After volcanic eruption on cooled + solidified lava
Outline of primary succession
Pioneer species colonise
Change environment to be less hostile so
New species colonise area
Outcompete pre existing species
Increase biodiversity
Reach climax community
Does succession show evolution?
NO
shows how pre existing species colonise an area over time
Pioneer species
First pre existing species that colonise an area (that previously had no life nor pre existing soil) over time
In primary succession
What do pioneer species do to habitat in primary succession?
Change the environment
So it is less hostile to other species
After pioneer species change environment in primary succession what happens?
Other species will colonise the area
What do the intermediate species do in succession?
Colonise once there is this change and will eventually outcompete the previous species e.g. abiotic factors or for food sources
Why does biodiversity of a community increase in primary succession?
Because increase in species richness when new species were introduced and able to colonise area and outcompete pre existing species
Climax community
Long term stable community at end of succession
What happens one climax community is reached?
Abiotic factors stay almost constant
Population size remains at carrying capacity (max possible number of species in population)
Why do species allow progression of succession when they die ?
Die —> decompose: by saprobionts in soil:
-add humus to soil which retains water in soil
-increase conc of phosphate ions in soil
Why does succession increase biodiversity?
Plants/ prey animals colonise area
Can support wider variety of animals that eat these by larger supply of food so continue succession (other animals can colonise area if food source is here) AND
Number of species in an area increases, creates more habitats and niches for wildlife = greater variety of food sources for animals.
Prevention of soil erosion to continue succession
Plant species roots can bind the soil together to prevent erosion so continue to support more life
Thus plant species allow continued succession
Secondary succession
Succession (colonisation of a pre existing species and subsequent changes in a community in a given area) beginning again in an area where life existed before, after some kind of environmental change.
Why is secondary succession faster than primary succession/
Since soil already exists if life existed before there
And the soil may already have seeds contained in it
