1. Ecological Succession

2. Ecological Succession
Process by which communities in a particular area change over time
Early communities modify the environment causing change to occur
This affects biological community as well
How?

3. Each successive (new) community is more favorable for new species
Changes in stages until a climax community is established

4. Composition of the community changes with time
Past
Community
Future
Community
Present
Community
Some species in the
past community were
out-competed, and/or
did not tolerate altered
abiotic conditions
Modifies such abiotic
factors as:
Light intensity
Wind speed
Air Temperature
Soil composition
Light quality
Wind direction
Soil water
Humidity
Changes allow new
species to become
established.

5. Primary Succession Regions with no existing community Bare rock
Receded glaciers
Volcanic regions
Krakatoa, Glacier Bay
Climax
Community
Lichens, bryophytes
And annual herbs
Slower growing
broadleaf species
Grasses and
Small shrubs
Fast growing
trees
Bare Rock
years

6. Pioneer Species
First organisms to live in a new community. Usually brought in by wind or animals

7. Secondary Succession Takes place after a land clearance
Fire, landslide, forest clearing
Soil is already there
More rapid than primary
Climax
Community
Open pioneer
community
(annual grasses)
Mature
woodland
mainly oak
Primary
bare earth
Grasses and
low growing
perennials
Scrub: shrubs
and small trees
Young broad-
leaved
woodland
150+
1-2 years
3-5 years
16-30 years
31-150

8. Gap Succession In a forested area with a thick canopy
Reduced light on soil
When a tree falls sunlight fills forest floor
New communities are formed

9. Wetland Ecological Succession
In open body of water, aquatic plants are introduced
Increase in aquatic plants causes sedimentation
Swamps may occur and in warmer months may dry off
May lead to EUTROPHICATION
More production (photosynthesis)
Lead to reduced oxygen and fish kills
Natural and anthropogenic
Type of pollution

10. Aerial view of Lake 227 in Note the bright green colour caused by algae stimulated by the experimental addition of phosphorus for the 26th consecutive year. Lake 305 in the background is unfertilized.