Download Succession and Limiting Factors

Succession
Discuss with your group…
What kind of
animals do you
think will be
present at each
level?
Today’s Objective:
• Describe how events and processes that
occur during ecological succession can
change populations and species
diversity.
• If grass were no longer cut on a lawn, what
would it look like in a year?
• Five years?
• In 90 years?
Succession: Changes over Time
• Ecologists refer to the natural changes that take place
in an ecosystem over time as succession.
• Succession occurs in very 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.
• ‘starting from scratch’
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.
• Succession occurs until a stable, mature
community develops 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 (space)
• 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
Climat
e
Atmospheric
gases
Temperatur
e
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.