Changes in Ecosystems:
.
Ecological Succession
• Do all ecosystems stay the same
all the time?
• What are some things that cause
changes to ecosystems?
–Natural and unnatural (Quickly and
slowly)
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
Ecological succession
• Series of predictable changes that
occur in a community over time.
Caused by:
– Physical environment
– Natural disturbance
– Human disturbance
Primary Succession
• Begins in a place without any soil
– Sides of volcanoes
– Landslides
– Glacier melting
• Starts with the arrival of living
things such as lichens that do not
need soil to survive, called
PIONEER SPECIES.
Pioneer species
http://www.life.uiuc.edu
Primary Succession
http://www.uncw.ed
u
http://uisstc.georgetown.edu
Pioneer
species:
Lichens,
don’t need
soil to
grow
They die and
adding
organic
material
Simple
plants like
mosses
and ferns
can grow
in the new
soil
The simple
plants die,
adding more
organic
material
The soil
layer
thickens,
and grasses,
wildflowers
and other
plants begin
take over.
This plant die
and add more
nutrients to
the soil
Shrubs
and trees
can
survive
now
Insects,
small
birds,
and
mammals
have
begun to
move in
What was
once bare
rock now
supports
a variety
of life
Reaching a mature
community can
take CENTURIES.
Secondary Succession
• Begins in an area where the ecosystem
has been disturbed, but where soil and
organisms still exist.
• Occurs faster and has different pioneer
species than primary succession
• Succession following a disturbance
that destroys a community without
destroying the soil
– Fires
Natural
– Hurricane
- Forest clearing
Human disturbance
- Farming
Secondary succession
• Unlike primary succession, secondary
succession occurs in a place where
and ecosystem currently exists.
• And occurs more rapidly than primary
succession.
http://www.geo.arizona.edu
http://www.ux1.eiu.edu
Climax Community
• A stable group of plants and animals that
is the end result of the succession process
• Does not always mean big trees
– Grasses in prairies
– Cacti in deserts
Think-Pair-Share
Shoulder Partners
• PAGE 408-410
PRIMARY
SUCCESSION
SECONDARY
SUCCESSION
References:
• http://www.slideshare.net/radhakrishnan19
62/ecological-succession-1
• Science explorer Prentice Hall.
Environmental Science
Succession in Marine Ecosystems
• Deep and dark
• Can succession happen?
• 1987 dead whale off of California
– Unique community of organisms living in
remains
– Represents stage in succession in an
otherwise stable, deep-sea ecosystem
– Whale-fall community
Whale-Fall Succession
• Begins when large whale dies
– Sinks to barren ocean floor
– Scavengers and decomposers flock to carcass , our first community
• Amphipods
• Hagfish
• sharks
• After a year, most tissues have been eaten
– Now, second small community of organisms live here
– Body is decomposing, releasing nutrients into the water
•
•
•
•
Small fishes
Crabs
Snails
worms
• Only skeleton remains…
– Third community moves in
• Heterotrophic bacteria
• Decompose oil in bones release of chemical compounds
• Who uses these chemical compounds?
– Chemoosynthetic autotrophs
• In come the crabs, clams, and worms that feed on this bacteria