Limiting Factors in Ecosystems
* What are limiting factors?
• An ecosystem only has a certain amount of food, water, space and shelter to support a
certain number of organisms.
• These are called limiting factors, or a conditions or resources that keep a population at a
certain size.
• Relationships between numbers of organisms and the resources available in an
ecosystem is described as the balance of nature.
•
* What happens if there is a change?
• If any limiting factors change, animal and plant populations may also change.
• Some changes may cause a population to decrease others may cause a population to
increase.
Examples:
• Giant Pandas are decreasing due to the loss of their habitat (limiting factor = SPACE)
• Snow Leopard – decreasing due to loss of habitat and prey (limiting factors = SPACE and
FOOD)
•
* Increases in Populations
• Increase in populations may result in overcrowding.
• May grow too large for environment to support.
Examples:
Plants
=
Animal
Populations
Population
of Predators
= Population
of Prey
Population of
Prey
= Population of
__predators
* Decreases in Population
Sometimes limiting factors cause decreases in population.
Examples:
• Water decreases , then animals needing water decrease then animals eating those
animals will decrease
• If trees are cut down or die because of disease, then animals needing those trees will die.
• If organisms no longer have enough space to survive, then they move or die. This is
influenced by human impact or natural hazards.
Shelter
*Natural events
(fire)
*Human
invasion
Food
*Competition
*Predators
*Disease/hunting
*Decrease of prey
LIMITING
FACTORS
that impact
population
sizes
Space
*Overcrowding
*Changes in
resources
Water
*Climate
*weather
changes
*Drought
Think About It….
A) We know that in the grasslands of Africa, wildebeests graze on the grasses but they
must watch for predators like cheetahs and lions. Suppose there were no predators
for the wildebeests. What would most likely happen to this population?
B) If many trees in a rainforest were cut down, what would happen to the population of
koala bears living in them? What would in turn happen to the population of jaguars
that rely on the koala bears as a source of food?
C) Drought strikes a desert. How would this limiting factor impact the small rodents
living there? Would this have an impact on coyotes? Why or why not?