Transcript Ecological Succession

Warm-up: Succession
• Read the Case Study,
“Communities Maintained by Fire”
on pages 130 – 131.
• Write two things you have learned and
• answer questions #1 & 2.
Warm-up Answers
• 1. New things you have learned…
•
The purple plant Fireweed covers the burned
forest areas of the Rocky Mountains.
•
Ecological Communities (Biomes) that are
maintained by fire are:
Chaparral of California, Temperate Grasslands of
the Midwest, many Southern and Western Coniferous
forests.
•
Seeds of some species will not germinate until
exposed to temperatures of several hundred degrees.
Warm- Up Answers (cont’d)
• #1. A young longleaf pine is low to the
ground, so it can survive fire that sweeps
through the canopy.
Deciduous trees may burn because
they are not as low to the ground.
Warm-up Answers (cont’d)
• #2. The tallgrass prairie, have evolved in an
environment of frequent fires. In these
communities, controlled fires can kill any
competitors that try to move in to the ecosystem.
• Disadvantages to using fire:
• Risk to human property
• Chance that competitive species may not be
destroyed.
Changes in Ecosystems:
Ecological Succession
What is Ecological Succession?
• Natural, gradual changes in the
types of species that live in an
area
• Can be primary or secondary
• The gradual replacement of one
plant community by another
through natural processes over
time
Primary Succession
• Primary succession occurs where there
was no previous community, such as on
bare rock or sand.
• Begins in a place without any soil:
»Sides of volcanoes
»Landslides
»Flooding
»Glacial retreat
• Primary succession begins with
PIONEER SPECIES.
Pioneer organisms can tolerate extreme
conditions: hot and cold; dry and wet.
Moss, dune grass, and lichens are pioneer
organisms.
• First, lichens that do not need soil to
survive grow on rocks
• Next, mosses grow to hold newly made
soil
Pioneer Species
Lichens break down rock to
form soil.
Low, growing moss
plants trap moisture
and prevent soil
erosion
Lichens
Lichens are algae and fungus growing
together in a mutualistic relationship.
Algae make the food
• Fungus anchor and capture water.
Primary Succession
• Soil starts to form as lichens and
the forces of weather and erosion
help break down rocks into smaller
pieces
• When lichens die, they decompose,
adding small amounts of organic
matter to the rock to make soil
Primary Succession with lichens and mosses.
Primary Succession
• Simple plants like ferns and mosses
can grow in the new soil
Primary Succession
• The simple plants die, adding more organic
material (nutrients to the soil)
• The soil layer thickens, and grasses,
wildflowers, and other plants begin to take
over
Primary Succession
• These plants die, and they add more
nutrients to the soil.
• Shrubs and trees can survive now.
Primary Succession
• Insects, small birds, and mammals have
begun to move into the area.
• What was once bare rock, now supports a
variety of life.
Warm-up: Primary succession
1.Explain some of the adaptations of
plants, especially in California’s
Chapparal Biome.
Ceanothus americanus (pictured below) has leaves
covered with flammable resins that help fuel a fire.
This adaptation benefits the species because
ceanothus seeds require intense heat for
germination.
“Fire-resistant” roots also enable the plant to
resprout quickly in recently burned areas.
Knobcone pine (pictured below) have seed cones
that require the heat of a fire to open. The seeds are
protected from fire behind tightly closed resincoated scales, often so well insulated that even
when the outer part of the cone is charred, the seeds
inside are protected. High temperatures cause the
cone to open, releasing the seeds that fall to the
ground into a cool bed of ash and mineral soil.
Secondary Succession
• Begins in a place that already has
soil and was once the home of
living organisms
• Occurs faster and has different
pioneer species than primary
succession
Secondary Succession
• Newer communities make it harder
for the older communities to survive.
– Example: Younger birch trees will
have a harder time competing with
taller, older birch trees for sun,
but a shade loving tree may replace
the smaller birch trees.
When does secondary
succession occur?
• After forest fires
• After cultivated land is abandoned
• Temporary flooding from storms, etc.
Climax Community
• A relatively stable group of plants
and animals that is the end result of
the succession process
– However, stability never happens for long in
ecology! The only constant is CHANGE!
• Does not always mean big trees
– Grasses in prairies
– Cacti in deserts
• The following slide is an example of
the Secondary Succession of a deep
freshwater pond.
Crash Course video, Succession (10:02)
http://www.youtube.com/watch?v=jZKIHe2LDP8
Bozeman, Ecological Succession (6:21)
http://www.youtube.com/watch?v=V49IovRSJDs
Succession Song, Mr. Parr (3:58)
http://www.youtube.com/watch?v=rzE6BNNLew0
Animation with bird, Succession (6:22)
http://www.youtube.com/watch?v=k03vxRYsJ4Y