Download Chapter 5:

Ecology How Ecosystems Work
Where does energy
come from?
All energy in an ecosystem
stems from the sun.
Producers make this
energy into useable
energy for consumers.
Producers
• Makes own food (autotroph)
• Photosynthesis:
Carbon Dioxide + Water +Solar
Energy =
Sugar (carbohydrate)+
Oxygen
Consumers
Get energy from other
organisms
(heterotrophs)
Types of consumers:
• Herbivore
• Carnivore
• Omnivore
• Decomposer
• Cow, sheep, deer,
grasshopper.
• Lions, hawks,
snakes, spiders.
• Bears, pigs,
humans.
• Fungi, bacteria
Exception to sun rule…
Deep in oceans where the
sunlight can not get, there are
ecosystems around
hydrothermal vents. Energy
stems from bacteria that
convert hydrogen sulfide into
make their own food.
Cellular Respiration
• Used to get energy out of
carbohydrates:
Sugar + Oxygen =
Carbon Dioxide +
Water + Energy
Sugar
C6H12O6
+ oxygen
CO2
+
H2O
+
Energy
Transfer of Energy
• Energy is transferred from
one organism to another
when one organism
consumes another.
• Each time energy is transfers
it is called a trophic level.
Trophic Levels can be
expressed through
food chains and food
webs.
Food Chain
*A sequence
in which energy
is transferred
from one
organism
to
another.
Food Web
• Because most animals eat more than one
type of food, a food web shows multiple
chains linked together.
Energy pyramid
• The tree is the lowest
trophic level and has the
highest amount of energy.
• Each increasing trophic
level has less energy
available to it due to loss of
heat and other
conversions.
Trophic levels:
• Ecosystems rarely have
more than 4-5 trophic levels
because there simply is not
enough energy to support
higher levels.
The Cycling of Materials
In an ecosystem materials
are constantly reused.
• The Carbon cycle
• The Nitrogen cycle
• The Phosphorus cycle
The Carbon Cycle
• Carbon is an essential
component of proteins, fats,
and carbohydrates which
make up all organisms.
The Carbon Cycle
Carbon is cycled between:
• Land-limestone & fossil fuels
• Atmosphere-Carbon dioxide
• Water-Dissolved with in
• Organisms-protein, fats,
carbohydrates & bones/shells
Fossil Fuels
• Left over stored carbon from
bodies of dead organisms from
millions of years ago.
• Burning of fossil fuels along with
natural burning of wood or forests
= 6 billion metric tons of CO2
• Half of this stays in the
atmosphere, causes global
warming
The Nitrogen Cycle
• Organisms use nitrogen to
build proteins to build new cells.
• 78% of the gases in the
atmosphere.
• Most organisms cannot use
atmospheric Nitrogen.
Nitrogen Fixing Bacteria
•Fix atmospheric nitrogen
into chemical compounds
•Roots of legumes or in
soil
Decomposing Bacteria
• Break down the wastes of
animals, leaves and other
decaying organisms to return
the Nitrogen to the soil.
• Bacteria break some of the
nitrogen into nitrogen gas
The Nitrogen Cycle
Nitrogen cycles by…
• Atmosphere-Nitrogen
gas
•Bacteria-Nitrogen fixing
and decomposing
The Phosphorus Cycle
• Phosphorus is an essential
element for bones and teeth in
animals.
• This cycle is slow and does not
normally occur in the atmosphere
because Phosphorus does not
normally occur as a gas.
The Phosphorus Cycle
Phosphorus cycles…
• Earth-soil, rock, fertilizers
• Water-sinks to bottom
• Decomposition of plants
and animals
Fertilizers
• Fertilizers contain nitrogen and
phosphorus to help stimulate rapid
growth and bigger plants.
• Excess can enter terrestrial and
aquatic ecosystems leading to
rapid growth of algal blooms.
Algae can deplete oxygen
available to fish and other aquatic
life.
Acid Precipitation
• Burning coal, wood, or oil
releases nitric oxide
• Combines with oxygen and
water vapor to make nitric
acid (dissolves in rain &
snow)
How Ecosystems Change
• Ecological succession
–Primary succession.
–Secondary succession.
–Old-field succession.
Ecological Succession
• Gradual process of change
and replacement of the
types of species in a
community.
• May take hundreds or
thousands of years.
Primary Succession
• Occurs on a surface where
no ecosystem existed
before.
–Rocks, cliffs, and sand dunes
Secondary Succession
• Occurs in ecosystems that
have been disturbed by
humans, animals, or natural
processes such as storms,
floods, earth, quakes, and
volcanos.
Pioneer Species
• The first organisms to colonize
a newly available area and
begin the process of ecological
succession.
• Make it more habitable for
other species to move in.
Climax Community
• A final stable community.
• Still will continue to
change in small ways
over time.
Old-field Succession
• Occurs when farm land is
abandoned.
–Grass/weeds (w/in 1 year)
–Perennial plants/grasses (w/in 2
years)
–Shrubs (w/in 3-10 years)
–Pine forest (about year 20)
–Oak forest (about 150 years)
Succession
• Primary succession takes much
longer than secondary succession.
–Pioneer species generally tends to
be lichens that break down the rocks
(can live without soil). Mosses may
then grow, etc. starting the
succession process.