Download Succession

Succession
Primary
Succession
Time
Secondary
Succession
Discuss with your group…
1. Together, come up with a definition for
succession by looking at the pictures.
2. What is the difference between Primary
and Secondary succession?
Today’s Objective:
• describe how events and processes that
occur during ecological succession can
change populations and species
diversity.
Can be found in the book:
Pg. 65 - 69
• If grass were no longer cut on a lawn, what
would it look like in a year?
• Five years?
• In 90 years?
Ecologists can predict the changes that will take
place over time in an area….like evolution of an
environment
Succession: Changes over Time
• Ecologists refer to the natural changes that take place
in an ecosystem over time as succession.
• Succession occurs in predictable stages
• At each stage, different species of plants and animals
may be present.
Succession: Changes over Time
• As succession progresses, new organisms move in.
• Others may die out or move out.
There are two types of succession—
• primary
• secondary.
• The colonization of organisms in a completely
barren land is called primary succession.
• Primary succession takes place on land where there
are no living organisms.
PRIMARY SUCCESSION
• The first species to take hold in an area like
this are called pioneer species.
PRIMARY SUCCESSION
• As these first organisms die, more soil builds- and it
has more and more nutrients in it.
Exposed rock
Primary succession
• As soil builds, bigger plants will grow, bringing in
herbivores and eventually carnivores
SECONDARY SUCCESSION
• Secondary succession is the sequence of changes
that takes place after an existing community is
severely disrupted in some way.
• Secondary succession, however, occurs in areas that
still have land containing nutrients in the soil.- Not
completely starting from scratch, like primary.
• A stable, mature community that undergoes little
or no change in species is a climax community.
• In an evolving ecosystem, populations will
continue to grow until they reach their carrying
capacity.
• This is the maximum amount of organisms that
can survive in an ecosystem
– It is determined by the amount of resources available,
such as:
• Habitat
• Water
• Food
No population can live beyond the
environment’s carrying capacity for
very long.
● The “J” shape shows growth at a constant rate (exponential growth).
● When the “J” becomes an “S” shape…it means the population has reached
carrying capacity.
Life In an Ecosystem
• Conditions in one part of the world are suitable for
supporting certain forms of life, but not others.
Ranges in Tolerance
• The ability of an organism to withstand fluctuations in
biotic and abiotic environmental factors is known as
tolerance.
For example,
some crops may
survive a long
drought periodThey may not
produce as well,
but they’re able
survive.
This makes me think of “Children of the Corn” –
shut up, it was scary when I was little…..
• A limiting factor is any biotic
or abiotic factor that can
affect the existence of an
organism.
Common Limiting
Factors
Sunlight
Climate
Atmospheric gases
Temperature
Nutrients/Food
Fire
Soil chemistry
Amount of Space
Other organisms
Water
Limiting Factors
• Factors that limit one population in a community may
also have an indirect effect on another population.
For instance, what if a drought caused
grass to reduce the number of seeds it
produces…
What would happen to the mice that feed
on those seeds?
What would happen to the hawks that
feed on those mice?
What are some limiting factors for this
If it’s too dry, Mr. Frog little guy? And why?
can’t breathe…and if no
water around, can’t
reproduce.