LG: How Do Ecosystems Recover
from a Disturbance?
January 2013 Regents food web question
ECOLOGICAL SUCCESSION
is the series of changes that occur
in an ecosystem over time.
It can occur on LAND or
in AQUATIC
ecosystems.
There are TWO types of
succession on LAND.
1.
PRIMARY
2. SECONDARY
PRIMARY SUCCESSION
is the sequence of
communities that form in an
originally lifeless habitat.
Primary succession occurs
on BARE ROCK.
What could occur to give us
bare rock in a place that had
already had plants living?
Primary Succession
The first organisms (pioneer organism)
to appear are LICHENS.
Lichen is a FUNGUS and ALGAE living
in a MUTUALISTIC relationship.
The first living things to grow
successfully on a newly formed
sand dune are known as
a. saprophytes
b. pioneer organisms
c. carnivorous plants
d. heterotrophs
Lichens grow on
bare rock and break
down (weather) the rock
to form a thin layer of soil.
Primary Succession
The lichen make up a
PIONEER COMMUNITY.
A pioneer community is
the first one in a new
habitat.
Base your answer on the diagram below, which shows the
sequence of plant communities that have occupied land that
was left barren 300 years ago, and on your knowledge of
biology.
Which plant species represent pioneer organisms?
a.
broomsedge and pine seedlings
b.
ragweed and aster
c.
crabgrass and horseweed
d.
oak and hickory trees
Lichens & Mosses
Crevice Community
THE STAGES OF
PRIMARY SUCCESSION
1.Bare rock
2.Lichens & mosses (pioneer)
3.Grasses and shrubs
4.Trees (climax community)
Base your answer on the diagrams below of
four stages of a biological process and on
your knowledge of biology.
What would most likely be the predominant
life form found in stage I?
a. ferns
b. tracheophytes
c. mushrooms
d. pioneer species
A Typical New York
State Succession
A slab of bare rock is covered with lichens.
In time, mosses cover the rock, followed by
grasses, and finally by small shrubs and
tree saplings. In this example, the lichens
represent
a.
b.
c.
d.
a climax community
a dominant species
secondary consumers
pioneer organisms
A CLIMAX COMMUNITY
• is a diverse and mature community
that does not go through more
succession.
• should be able to withstand disruption
better than earlier ecosystems,
causing succession to stop
ECOSYSTEM STABILITY
•During succession, the stability
of an ecosystem changes
•Stability is the ability of an
ecosystem to remain constant
in the face of disturbance
Which organism is one of the first
autotrophs to appear in this
succession?
a.
b.
c.
d.
frog
aquatic plant
tree
fish
• As the diversity of an ecosystem
increases, the stability increases
• A more diverse ecosystem contains a
more complex food web
o This means an organism is more
likely to find an alternate food
source if need be.
Changes in an ecosystem over a long period of time are
shown in the diagram below.
These changes will most likely lead to a
a.
stable ecosystem that can last for many years
b.
loss of heterotrophs that cannot be recovered
c.
long-term rise in environmental temperatures
d.
forest consisting of only producers and decomposers
Base your answer on the diagram below,
which shows the sequence of plant
communities that have occupied land that
was left barren 300 years ago, and on your
knowledge of biology.
Dominant plant species in the climax
community include
a. pine trees
b. hickory trees
c. mosses
d. lichens
www.educeth.ch/stromboli/ perm/msh/life-en.html
The diagram below shows various ecological communities
that occupied an area over a period of 300 years.
Which statement best describes the diagram?
a.
Community A is the most stable community.
b.
Community B replaced community C after a period of
100 years.
c.
Community C developed into community A after a
period of 75 years.
d.
Community D modified the environment, making it more
suitable for community E
SECONDARY SUCCESSION
occurs where an existing
community has been
cleared by some
disturbance but the soil
is not destroyed.
Secondary Succession
DEFORESTATION and
FIRE are
disturbances
that will clear
the existing
community but
not destroy
the soil.
Secondary Succession
Over a long period of time, the stages represented in
the diagram below were each present in a particular
ecosystem.
After a forest fire, what is the most likely order in
which these stages appeared?
a. D C A B
b. B D C A
c. A B C D
d. B C D A
Aquatic Succession
Aquatic HABITATS are in
WATER.
Over long periods of time
ponds fill in slowly with
sediments and plants.
Aquatic Succession
The ponds fill
in over time
to become
a marsh,
a meadow or
eventually
a forest.
Which statement best describes one of the stages
represented in the diagram below?
a.
The mature forest will most likely be stable over a long
period of time.
b.
If all the weeds and grasses are destroyed, the number
of carnivores will increase.
c.
As the population of the shrubs increases, it will be held
in check by the mature forest community.
d.
The young forest community will invade and take over
the mature forest community.