Transcript CHAPTER 2 – PRINCIPLES OF ECOLOGY

CHAPTER 2 –
PRINCIPLES OF
ECOLOGY
Section 2-2: Nutrition and Energy
Flow (p.46-57)
How Organisms Obtain Energy

An important
characteristic of a
species niche is how it
obtains ENERGY
 Ecologist trace the flow
of energy through
communities to discover
nutritional relationships
between organisms
How Organisms Obtain Energy
 The
ultimate source of energy
for life is the SUN
 Plants use the sun’s energy
to manufacture food in a
process called
Photosynthesis
Autotrophs
 An
organism that uses light
energy or energy stored in
chemical compounds to
make energy-rich
compounds


Also called a producer
Examples:
• Grass
• Trees
• Algae
Heterotrophs
 An
organism that
cannot make its
own food and
feeds on other
organisms
 Can feed on
autotrophs or
other
heterotrophs
Herbivore
A
heterotroph
that only feeds
on plants
 Examples:
Carnivores
A
heterotroph
that only eats
other
heterotrophs
 Examples:
Scavengers
 Do
not kill for food
 Eat already dead
animals
 Examples:
 Role
benefits
ecosystems –
recycles nutrients
Omnivores
 Organisms
that eat
both plants and
animals
 Examples:
Decomposers
 Break
down the
complex
compounds of
dead and decaying
plants and animals

Nutrient recycling
 Examples:
Flow of Matter and Energy in
Ecosystems
 As
you eat food, such as an apple, you
consume Matter
 Matter flows through the levels of an
ecosystem from producers to consumers
Food Chain

A simple model that scientists use to show how
matter and energy move through an ecosystem
 Example:

A portion of energy is given off as HEAT
Trophic Levels
A
feeding step in a food chain
 First Order



Eats autotrophs
Herbivore
Example
 Second



Order
Eats first order organisms
Carnivore
Example
Food Web
A
model that represents all the possible
feeding relationships at each trophic level
in an ecosystem
 More realistic because…

Most organisms depend upon more than one
other species for food
 Let’s
look at an example of a food web…
Ecological Pyramids

Can show how
energy flows through
an ecosystem
 Base represents:


Autotrophs (1st trophic
level)
Higher levels
represents:

Heterotrophs (2nd, 3rd,
trophic levels)
3 Types of Pyramids
Energy
 Shows
how much
energy is transferred
from producers to
consumers
 Energy decreases
10% at each level
Numbers
 Shows
population size
decreases at
each higher
trophic level
 Not always true

Thousands of
insects can eat
off one tree
Biomass
 Represents
the
total weight of
living matter at
each trophic
level
Cycles in Nature
 Matter
is constantly recycled.
 It is never LOST!
The Water Cycle

Life on Earth depends upon WATER
 How the cycle works:

Evaporation
• Liquid to gas (called water vapor)

Condensation
• Water vapor condenses on dust in air + forms clouds

Precipitation
• Water falls to ground in form of rain, ice, or snow

Transpiration
• Loss of water by plants – puts water vapor into air
What is looks like…
The Carbon Cycle

Carbon is an important part of all living things

Makes up all molecules of life –
• carbohydrates, proteins, fats, nucleic acids

Parts of Carbon Cycle:

Photosynthesis
• Autotrophs use CO2 from air to make energy-rich compounds

Respiration
• Both autotrophs + heterotrophs use CO2 in processes and
release CO2 back into the evironment

Other ways:
• Death + decay
• Burning of fossil fuels
• Fires
What it looks like…
The Nitrogen Cycle

Atmospheric Nitrogen


Nitrogen-fixing bacteria


Nitrogen makes up 78% of atmosphere
Bacteria found on roots of plants fix nitrogen into
different compounds in the soil
Animal consumption



Eat plants or other animals
Waste materials enter ground
Decomposers – put Nitrogen back into atmosphere
What it looks like…
The Phosphorus Cycle
 Short



Plants get P from soil
Animals eat plants – get P
When animals die, P gets returned to soil
 Long



term
term
P enters water
P gets absorbed into rocks
Millions of years later, rocks erode, releases P
back into cycle
What it looks like…