Transcript Forest Dynamics

Succession
•
A process of ecological change in which a
series of natural communities are established
and then replaced over time is
Succession
called_______________________
•
Succession that takes place on an area that was
originally completely empty of life is
called___________________
Primary Succession
Succession
•
Succession that occurs in an area where
an ecosystem exists but has been
disturbed is called _________________
Secondary Succession
Succession
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Plants or communities that are the first to
be established in an area previously
empty of life are called _______________
Pioneer Species
Succession
•
Plants with short life spans that devote
most of their energy to producing seeds
are called _________________________
Opportunistic Species
Succession
•
A relatively stable community
that is environmentally
balanced is called a
________________.
Climax community
Succession
•
Most of the entire
eastern US has been
clear cut for
agricultural use and
timber.
•
Today only a fraction
of the original old
growth forest remains.
Succession
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What are the most common pioneer plant
species in primary succession?
– mosses and lichens that grow on
rock.
Succession
•
What are the most common pioneer plant
species in secondary succession?
– annual weeds such as crabgrass
Succession
•
Why are the pioneer species in primary and
secondary succession different?
– Because in secondary succession
there is already soil present.
Therefore lichens and moss are not
necessary.
Pioneer species quickly occupy a site following clearing.
They grow rapidly to compete with grasses and shrubs.
As the crowns of pioneer species close, seedlings from
these trees are unable to survive in the resulting shade.
Different species that have a higher tolerance to shade
soon become established beneath the pioneers.
As the short-lived pioneers near the end of their life spans,
the more tolerant trees in the forest understory begin to
take over the site. The result is a major change in plant
and animal species.
Beneath the second successional stage species, that
often form thicker crowns than pioneers, new species that
are even more shade tolerant become established.
The process of succession continues until the most shade-tolerant
species suitable for the site (climax species) become established.
Seedlings of highly shade tolerant climax species thrive in
the shade of their parents. Because of this, climax species
will persist until disturbance sets back the succession
process to the pioneer or some other stage.
Forest Succession
• Takes place over hundreds of years.
• Species of climax forest will vary with
geographic location
–
–
Beech Maple
Oak Hickory
NJ Pine Barrens
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http://www.pinelandsalliance.org/exploration/channel/
Deviates from the
typical pattern of
eastern deciduous
forest succession.
Example of “fire
disclimax.
NJ Pine Barrens