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Ecological
Succession
Ecological Succession
Ecological Succession – the natural replacement of one community of organisms by another
Ecological Succession
Each stage of succession changes the ecosystem and creates conditions that are favorable for a new group of organisms.
Ecosystems are constantly changing!!!!
Follows any disturbance in an ecosystem
Heavy rain, tornados, forest fires, hurricanes, land clearing, etc.
Primary Succession Starts with BARE ROCK or
BARE SAND
Might be caused by a volcanic eruption, glacier movement, or extreme erosion.
(no soil)
Order of Primary Succession
1) Lichens and Mosses
Pioneer species – the first organisms that move into a devastated area
Must be able to live in a hostile environment or with limited resources
Help create soil by leaving behind organic matter when they die
Order of Primary Succession
2) Grasses and small animals
Die and leave behind organic matter
3) Small shrubs and more animals
Die and leave behind organic matter
Slowly soil builds up in an area
Order of Primary Succession
4) Small trees and 5) Larger trees
Seeds are brought in by animals, wind, and water
Die and leave behind organic matter
Order of Primary Succession
6) Climax Community – a stable ecosystem with little change in the composition of species
The end result of ecological succession
Climax communities look different in different parts of the world.
But, they don’t last forever…
A disturbance can happen at any time and succession will begin again…
Primary Succession
How long does it take?
Hundreds of years
Very SLOW process
Secondary Succession
What’s there at the beginning?
Soil (full of nutrients and seeds)
Life has already existed in this area.
Caused by disturbances like fire, floods, and tornados
Order of Secondary Succession
1) Grasses and weeds
2) Small shrubs
3) Trees
4) Climax Community
Secondary Succession ~ Example In 1988, a forest fire destroyed in much of
Yellowstone; this picture was taken 17 years later.
Secondary Succession
How long does it take?
20 – 50 years
Depends on the environment
Much FASTER because the soil is already present
