Download 7 - Ecological Succession

Aim: How do ecosystems change over
time?
Ecological Succession1
• The process by which an ecosystem
changes over time – often from a barren
piece of land to a complex ecological
community (depending on climate)
Ecological Succession In a Forest
• As time passes grasses grow & then
get replaced by shrubs and eventually
a forest will form.
• Why do the grasses disappear?
–The large shrubs and trees prevent
light from reaching the grasses.
Ecological Succession in Ponds &
Lakes:
As time progresses, the pond gets filled
in with dead organic matter. The
dead organic matter takes the place of
the water in the pond or lake.
Eventually (through succession) a
forest may form where the pond once
was.
What is the final state of ecological
succession
• A climax community with great
biodiversity
Plant adaptation / succession 1:48
Destruction of Climax Communities
• Fires, volcanic eruptions, tsunamis,
deforestation, acid rain.
• Their destruction often (but not
always) means the birth of a NEW
community via succession.
Are forest fires an ecosystems
worst nightmare? Why or why not?
Fire in the Forest 2:25
Soil Formation:
• Lichens (fungus and green algae) &
weather break down rock into its
minerals.
• Dead Organic materials are added to
the minerals
Maintaining Soil:
• The plant roots hold on to the soil &
prevent erosion (washing away of
valuable material).
• How could erosion cause a problem
for an ecosystem?