Limiting Factors

A limiting factor

is an abiotic or

biotic factor that

restricts the

number of

individuals in a

population.

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Limiting Factors

Limiting factors can

include:

1. Competitors

2. Disease and parasites

3. Weather

4. Fires

5. Available habitat

6. Predators

7. Birth & Death Rates

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1. Competitors

Red-Tailed Hawk

Barred Owl

•Competition results when

organisms struggle to

survive in a habitat with

limited resources

•Birds of prey: live in forests

on the edge of fields

•Eat mice and other rodents

•Nest in trees

•Live in same habitat, use

same resources, so they

compete with each other

http://www.greenpeace.ca/e/http://www.pinebarrensphoto.com/Barred-owl-sSc.jpg

2. Disease and Parasites

Diseases and

parasites can be

dependent on

population size and

habitat

Larger population =

more parasites and

disease = limit how

big population gets

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3. Weather

Storms

Drought

Flooding

Extreme heat/coldThese extreme types of

weather can change the living

situation of an organism,

which can change if the

population can survive or not.

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4. Fires

Fires lead to

succession which is

a predictable

change in the

community over

time.

Fires can destroy

habitats.

http://www.greenpeace.ca/e/

5. Available Habitat

Human activities play a

large role

Development (homes,

buildings, parking lots),

damming rivers, clearing

forests, hunting.

Parts of the habitat can

also be limiting: amount

of food (prey), available

nesting sites

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6. Predators

Predator-prey

relationship can

be a delicate

balance

between the

two

populations.

http://www.greenpeace.ca/e/

Predators

As the prey

population

increases, the

predator population

increases.

As the prey

population

decreases, the

predator population

decreases.

http://www.greenpeace.ca/e/

Example: Lynx and Hare:

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Birth & Death Rates

Birth rate: the number of births per 1,000

individuals for a given time period

Death rate: the number of deaths per 1,000

individuals for a given time period

Birth rate higher than the death rate =

population growth

Death rate higher than the birth rate =

population decline

Birth rate is the same as the death rate = no

change

http://www.greenpeace.ca/e/

Immigration & Emigration

The size of a population can also change due

to organisms moving in or out of the

population.

Immigration: an organism moving into a

population

Emigration: an organism leaving the

population

Example: If an organism’s food supply is

scarce, it will leave to find other food.

http://www.greenpeace.ca/e/

What is Carrying Capacity?

Carrying capacity is

the maximum

number of individuals

of a species that an

ecosystem can

support.

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What is Carrying Capacity?

Because of these limiting factors, each

ecosystem has a capacity for growth

connected to its carrying capacity.

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