Ecosystems
Part 1
• An ecosystem includes all of the
organisms as well as the nonliving
things in a given area.
Ecosystem
Ecosystem
Community
Community
Population
Population
Organism
Organism
• A community is a group of
different species that live
together in one area.
Community
Community
Population
Population
Organism
Organism
An ecosystem includes both biotic and
abiotic factors.
anything that is LIVING is considered
biotic.

 Examples:




plants
animals
fungi
Bacteria
plants
Abiotic
factors are nonliving things.
– anything that is
NON-LIVING is
sunlight
considered abiotic.
Examples:
– moisture
moisture
– temperature
– wind
– sunlight
– Soil
– https://www.youtube.com/watch?v=E1pp_7-yTN4
Carrying
Capacity and
Limiting Factors
Carrying Capacity
 What
exactly is carrying capacity?
 Carrying
capacity refers to the number of
individuals a certain habitat or area can
support given the resources that are
available
Carrying Capacity
 All
animals need basic things to survive and
they must get these things from their habitat
 Animals




Food
Water
Shelter
Space
need
Carrying Capacity
 No
matter where you are on planet Earth,
there will be some resources that are in short
supply
 For



instance:
In a desert water is very scarce and hard to find
In a rainforest space is limited
In the mountains food might be hard to come by
Carrying Capacity: Home
Life
 Think
about your home
 Everyone
might have their own bed, a
place to put their clothes, enough food to
eat and water to drink, as well as an area
they can go to and relax
Carrying Capacity: Home
Life
 Now
imagine that 5 people moved in
 What
would happen?
 What
would happen if 10 people
moved in?
 How
about 30 people?
Carrying Capacity:Home
Life
 Just
like in nature, your home has a carrying
capacity: a certain number of individuals that
can live there and still find everything they
need
 Once
you go above that number, life
becomes very difficult!
All Habitats Have
a Carrying
Capacity
 All
places have a certain number of individuals
that can live there and still gain everything
they need
 Once
the number of individuals pass that
number, life gets harder and harder
Ecosystems
Limiting
Factors
Let’s suppose….

We have two mice…:
and they
produce the
standard 56
“pups” (baby
mice) each
year.
and each of
these mice
goes on to
have 56
babies each
year….
Soon…..
 We’d
be over-run with mice on the planet!!
Why doesn’t this occur?
Limiting Factors
A
limiting factor
is an abiotic or
biotic factor
that limits the
number of
individuals in a
population.
Limiting Factors
 Limiting
1.
2.
3.
4.
factors can
include:
Space
Food
Water
Disasters: fire, flood,
drought, disease
SPACE
Human
activities play
a large role
Development,
damming
rivers, clear
cutting forests.
Predators: Food
 As
the prey
population increases,
the predator
population increases.
As the prey
population
decreases, then so
does the predator
population.
Example: Lynx and Hare:
Disaster: Drought
 If
a drought comes
along, the water
supply goes down.
 The number of
animals living in or
near the water would
decrease because
there would not be
enough water to
support a larger
number of animals.
https://www.youtube.com/watch?v
=8FPMP41LYJ8
Part 2: Producers and
Consumers
Producer
 Makes
food by changing light energy of
the sun into chemical energy, or food
 Also called Autotrophs
 Ex. Plants, algae, some bacteria
Consumers
 Organisms
own food
 Also
 Ex.
that do not make their
known as HETEROTROPHS
Rabbits, Deer, Mushrooms
Heterotrophs
 Consumers
 A.
Herbivores – eat ONLY plants
 Ex.
– Cows, Elephants, Giraffes
Heterotrophs
 Consumers
 B.
Omnivores – eat BOTH plants and
animals
 Ex.
– Bears and Humans
Heterotrophs
 Consumers
 C.
Carnivores – eat ONLY other animals
 Ex.
– Lions, Tigers, Hawks
 https://www.youtube.com/watch?v
=O_4HozC8qww
Heterotrophs
 Consumers
 D.
Scavengers/Detritivores – feed on
the tissue of dead organisms (both
plants and animals)
 Ex.
– Vultures, Crows, and Shrimp
Heterotrophs
 Consumers
 E.
Decomposers – absorb any dead
material and break it down into simple
nutrients or fertilizers
 Ex.
– Bacteria and Mushrooms
Part 3: Food Chains
 https://www.youtube.com/watch?v=Cd1
M9xD482s
Food Chain
Food Chains
 The
energy flow from one trophic level to the
other is know as a food chain.
1. The SUN begins ALL food chains.
2. Next, are the PLANTS, AKA Primary Producers
3. After producers are PRIMARY CONSUMERS
4. Then, SECONDARY CONSUMERS
5. Next, the TERTIARY CONSUMERS
 Some food chains will go to another level,
but most don’t go beyond four levels.
 ALL food chains end with DECOMPOSERS.
Each step in a food chain is called
trophic level
a ___________.
The trophic level indicates:
the organism’s position in the
sequence of energy transfers.
Trophic Level
The first trophic level in a food chain is always made up of
producers
_________. These organisms are referred to as
primary producers
_________________.
The second trophic level is occupied by the
herbivores
producers These
__________ that feed on the _________.
consumers
organisms are referred to as Primary
_________________.
Trophic Levels (feeding levels)
Secondary
Consumers
(carnivores or omnivores)
Primary
consumers
(Herbivores)
Primary
Producers
(Autotrophs)
Predators
___________________
of herbivores
_ belong to the third
level. These organisms
are referred to as:
secondary consumers.
Each consumer depends
on the:
trophic level below it for
energy.
Most ecosystems contain
only ____________
three or four
trophic levels.
Food webs
Trophic Levels: Primary Producer,
Primary Consumer, Secondary Consumer,
Tertiary Consumer?
Grass
Mouse
Grasshopper
Frog
Owl
Hawk
Trophic Level:
Producer, primary consumer, secondary
consumer, tertiary consumer
Grass
Producer
Mouse
Primary consumer
Grasshopper
Primary consumer
Frog
Secondary consumer
Owl
tertiary consumer
Hawk
Secondary consumer
Part 4: Food Webs
 http://studyjams.scholastic.com/studyjam
s/jams/science/ecosystems/foodwebs.htm
Food web
Food web:
The network of complex
interactions formed by the
feeding relationships among
the various organisms in an
ecosystem.
A food web links all
the food chains in an
ecosystem together.
In an ecosystem, the
feeding relationships
between organisms are
much too complex to be
shown in a …..
….. single food chain.
Many consumers eat:
more than one type of
food.
More than one species
may feed on:
There are many complex
interactions between many the same organism.
Food Webs
different food chains.
A
QUICK
REMINDER…
What is the primary source
of energy for an
ecosystem?
What do the
plants do
with the
glucose they
produce?
half of the glucose
About ____
is used immediately in
cellular respiration
_________________.
Respiration is the
conversion of:
glucose into molecules of
ATP, the energy source for
a cell.
Some of the glucose molecules are
used as raw materials (building blocks)
for the building of other _______
organic
compounds within the cell.
Much of the glucose is…..
…..stored by the plant for future use.
Part 5: Energy Pyramids
Energy Transfer Between Trophic
Levels
The amount of energy or
matter in an ecosystem can be
represented by an:
…..ecological pyramid.
Ecological pyramid:
A diagram that shows the
amount of energy contained
within each trophic level in a
food chain or a food web.
10% of the total energy
Roughly ____
_________ in one trophic level is
consumed
passed to the
next trophic level
organisms in the ________________.
The pyramid shape of
the diagram to the
right represents the
low percentage of
energy transfer from
one trophic level to the
next.
Ecological Pyramid
Why is the transfer of energy to the
next trophic level so low?
energy possessed by the organisms at one trophic level
Not all of the ______
passed up to the next trophic level.
will be _______
consume for their own
use much of the energy they ________
Organisms ____
life processes such as respiration, movement, or reproduction.
___________
Many organisms at one
trophic level will
escape being eaten by the
_________________
_________
predators at the next level.
The energy
_______ of these
“_______”
escapees will not be
passed to the organisms at
the higher
_______ level.
The following is a hypothetical food chain:
grass ---> grasshopper ---> toad ---> black snake
The grass occupies what trophic
level?
It is the producer.
The grasshopper occupies what
trophic level?
The grasshopper is the primary
consumer.
The toad occupies what trophic
level?
Secondary consumer
The black snake occupies what
trophic level?
Tertiary consumer
If the energy content of grass is approximately 5,000
calories per square meter of land surface, then the
energy content of the black snakes should be
approximately how many calories per square meter?
Answer: About 5 calories per square meter.
The low rate of energy transfer
between trophic levels explains
why:
food chains rarely contain more
than a few trophic levels.
Organisms occupying the lower
trophic levels are usually much
abundant than organisms
more _________
belonging to the highest level.
There are many more grasses,
shrubs, and trees than there are
herbivores
__________.
There are many herbivores
(deer, antelope, gazelles) for
carnivore (lion)
each ______________.
Higher trophic levels
energy and
contain less ______,
therefore, they can support
individuals
fewer _________.
Transfer of Energy
 When
a lion eats a zebra, it does
not get all of the energy from the
zebra (much of it is lost as heat)
 Only
10% of the energy from one
trophic level is transferred to the
next – this is called the 10% rule
https://www.youtube.com/watch?v=Sciz
kxMlEOM
Ecological Pyramid
•
•
•
•
Which
Which
Which
Which
level
level
level
level
has
has
has
has
the
the
the
the
most energy?
most organisms?
least organisms?
least energy?
 Three
hundred trout are needed to
support one man for a year. The trout, in
turn, must consume 90,000 frogs, that
must consume 27 million grasshoppers
that live off of 1,000 tons of grass.
-- G. Tyler Miller, Jr., American Chemist
(1971)