2. WHAT IS ECOLOGICAL SUCCESSION?
A gradual process of
change and
replacement of some
or all of the species in
a community.
Can take 100’s or
1000’s of years.
Ends in a climax
community
3. WHAT IS A CLIMAX COMMUNITY?
Final, stable
community.
Generally remains the
same if undisturbed
Type of climax
community will vary
depending on
ecosystem
Climax community for a
desert is different from
tropical rainforest
Both primary &
secondary succession
end with a climax
4. WHAT ARE THE TWO TYPES OF SUCCESSION?
1.
PRIMARY
2.
occurs on a surface
where no ecosystem
existed before
Ex: rocks, sand dune,
new island
SECONDARY
Occurs on a surface
where an ecosystem
has previously
existed.
Ex: after fire,
volcano, flood,
abandoned farm
5. WHAT ARE THE STEPS OF PRIMARY
SUCCESSION?
Typical primary succession of forest:
Rock is physically & chemically
weathered & broken down to make
soil.
Physical- frost wedging- frozen water
expands & creates cracks
Chemical- pioneer species like lichens &
moss can secrete acids to dissolve rock.
Thin soil can support grasses
As grasses die & decompose they
contribute to soil layer and soil gets
thicker.
As soil thickens it can support larger
plant life like shrubs
First trees that grow are usually sun
loving trees like pines
As pines grow tall they shade their
saplings, saplings can’t get sun and
die off.
Shade loving trees like deciduous
trees (oak, hickory) grow under pines,
eventually outgrowing and replacing
6. WHAT ARE THE STEPS OF SECONDARY
SUCCESSION?
Soil is already established so
it doesn’t have to be created.
Takes less time than
primary
More common than primary
succession
Pioneer species- grasses,
weeds
Shrubs
Pine trees
Deciduous trees
3 examples:
After a fire
After a field is abandoned
Pond becomes a forest
7. FIRE & SECONDARY SUCCESSION
Some ecosystems rely
on natural fires to
maintain the ecosystem.
Ex: grasslands, chaparral
Fires are actually
beneficial:
Jack pine trees need
intense heat of fire to
release seeds
Animals eat new, soft
plants that sprout right
after fire when soil is
nutritious
Minor forest fires burn
accumulation of brush &
deadwood that would
otherwise contribute to
8.
9. OLD FIELD SECONDARY SUCCESSION
Farmers field becomes
a forest.
Pioneer species of
grasses establish
quickly due to rich soil.
10. POND TO FOREST SUCCESSION
Ponds can fill in and
become a forest if not
maintained.
Pond fills in with dead
leaves, debris, eroded
sediment.
Makes pond more
shallow.
Sunlight helps plants
grow in shallow pond
Eventually fills in
completely with
sediment & secondary
succession continues.
11. QUESTIONS TO ASK YOURSELF…
What is the difference
between primary and
secondary succession?
What role does a pioneer
species play during the
process of succession?
Why would putting out forest
fires be damaging in the long
run?
What role do lichens play in
primary succession?
How are lichens similar to the
pioneer species that colonize
abandoned farm areas?
How are they different?
Hinweis der Redaktion
Top picture- climax community for desertBottom picture- climax community for forest
The bottom picture is of a new show called Revolution. This show depicts what happens after the power goes out around the planet. Notice how secondary succession is taking over the Chicago baseball stadium.
Picture on bottom left: Jack pine cone BEFORE fire- seeds are inside sealed cone.Picture on bottom right: Jack pine cone AFTER fire- cone has popped open & released seeds.
