1. the process in which one ecosystem is gradually replaced by another
Succession
the process in which one ecosystem is gradually replaced by another

2. Primary Succession
involves the series of changes that begins with a bare landscape
Occurs in an area that didn’t have soil to begin with
ex) lava covered rock, glacial retreat zone
ends with ecosystem reaching maximum productivity for the environmental conditions
called a climax community

3. plants that can grow in very thin soil (mosses) join the lichens
Example:
pioneer organisms such as lichens are carried to the area by wind or birds
can live without soil or shelter, lichens break down rock and decay to form soil
plants that can grow in very thin soil (mosses) join the lichens
organisms that eat mosses move into the area
this causes more rock to break down, more decay and therefore more soil
a wider range of organisms can move into the area
a climax community is created

4. Secondary Succession
occurs when an ecosystem restores itself after a disturbance. It previously would have had vegetation (and soil).
ex) forest fire
process does not have to start with bare rock
can build on the remains of an old system
the new climax community is similar to but not exactly like the old

5. Important Points
succession can usually change disturbed ecosystems back into productive ones
severe disturbances can produce irreversible changes
this is especially true if soil or a species is poisoned over a large area
severely disturbed areas can stay unproductive for hundreds or even thousands of years
ex) Badlands of Alberta

6. The Drumheller Badlands are one of the few areas in the world where sedimentary layers from earlier geological periods have been scraped off by natural processes, exposing a rich deposit of animal and plant fossils and even complete dinosaur skeletons. No wonder the area the Drumheller Badlands canyons proved to be vast terrains of fossil discovery.

7. More Important Points Tree ‘Parking Lots’
Reforestation or “tree planting” does not allow for the natural succession of plant and animal species following a forest being levelled (fire, deforestation, etc.)
It does not put the natural ecosystem back even though a forest of trees may grow