Transcript Unit 4-2 Energy Flow in Ecosystems

Ecological Succession
A gradual development of a community over
time is
called succession.
Succession takes place
in all communities.
Sometimes, a small community starts to
grow in an area where other organism had
not previously lived. There is no soil in this
area. Usually, there is just bare rock.
Over a very long time, a series of organisms
live and die on the rock. The rock is slowly
transformed into soil. This process is
called primary succession. The first
organisms to live in an area are called
pioneer species.
PIONEER SPECIES:
First species to populate an area.
Primary succession is less common than
secondary succession and usually involves
volcanic activity or an area of rock uncovered by
melting ice.
Volcanic Island!
Receding Glacier!
Secondary succession is more common and occurs
more rapidly than primary succession. It is a series of
changes that occur in an area where the ecosystem
has been disturbed, but where soil and organisms still
exist. Examples include: natural disasters like fires,
hurricanes and tornadoes and human activities like
farming, logging or mining.
Review Graph on Page 39.
Chapter 2 – Ecosystems and Biomes
Section 2-1 Energy Flow in Ecosystems
Each and every organism in an ecosystem
fills a role of producer, consumer or
decomposer.
Producers (plants, algae and some bacteria)
use the sun’s energy to turn water and carbon
dioxide to food molecules through a process
called photosynthesis.
Consumers are organisms that obtain
energy by feeding on other organisms.
Herbivores eat only plants!
Carnivores eat only animals!
Omnivores eat both plants and animals!
Decomposers break down nature’s
wastes (detritus). Mushrooms (Fungus)
and bacteria are decomposers.
Food Chains and Food Webs!
The movement of energy through an
ecosystem can be shown in diagrams called
food chains and food webs.
Food Chain
Food Web
A Food Chain is a series of events in
which one organism eats another and
obtains energy. Food chains always
start with a producer.
The first level consumer feeds on the
producer and the second level consumer
feeds on the first level consumer.
A food web shows many overlapping
food chains in an ecosystem with
producers at the bottom and 1st, 2nd
and 3rd level consumers above.
Energy Pyramids show the amount of
energy that moves from one feeding
level to another in a food web.
The most energy is available at the producer
level of the pyramid. 90% of the energy at
each level is lost, used for the life processes
of the organism at that level.