1. Ecosystems
Limiting Factors

2. 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….

3. Soon….. We’d be over-run with mice on the planet!!
Why doesn’t this occur?

4. Limiting Factors
A limiting factor is an abiotic or biotic factor that restricts the number of individuals in a population.

5. Limiting Factors Limiting factors can include: Competitors
Disease and parasites
Weather /Climate
Fires
Available space/habitat
Predators
Food
Water

6. Competitors-organisms both cooperate and compete
Birds of prey
Live in forests on the edge of fields
Eat mice and other rodents
Nest in trees
Red-Tailed Hawk
Barred Owl

7. Diseases and parasites can be dependent on population size and habitat
Disease and Parasites
Diseases and parasites can be dependent on population size and habitat

8. Weather Storms Drought Flooding Heat/cold
These factors can limit population growth.
For example a cold spring can kill of members of a population.
Can you name some other weather that can limit growth?

9. Fires
Fires lead to succession which is a predictable change in the community over time.

10. Available Habitat Human activities play a large role
Development, damming rivers, clear cutting forests.

11. Space as a limiting factor
How do plant species suffer greatly from space as a limiting factor

12. Moving In and Out
Imagine if food is scarce in a forest/lake ecosystem.
What could the population of otters do to survive?

13. Answer
Some sea otters might move out of the ecosystem becoming their own population in a new area. This is called E(xit)mrigation
Challenge: why would some populations Immigrate or move in?

14. Food and Water
Imagine a giraffe must eat 10 kg of leaves a day. Say their habitat can supply 100 kg of leaves each day from trees
Can 15 giraffes survive here?

15. Apply It- Food and Water
No 15 giraffes cannot survive in that habitat.
The maximum is 10 giraffes. The maximum population an area can support is carrying capacity.
How do you think the other giraffes would survive?

16. Predators
Predator-prey relationship can be a delicate balance between the two populations.

17. Predators
As the prey population increases, the predator population increases. As the prey population decreases, then so does the predator population.

18. Example: Lynx and Hare:

19. Math: Population Density
Equation
Solve it
Density is how much matter in a given space (volume)
Population Density=
Number of animals in population
Area of habitat
There are 500 squirrels in city park
The squirrels habitat is 5 meters by 4 meters
What is the population density?

20. Explain 500 squared Solve for area (5 x 4)= 20 meters squared
25 squirrels/ meters squared
In every square foot there are 25 squirrels in city park.

21. EXIT TICKET
A forest ecosystem has an area of 100 meters squared. A population of deer call the forest their habitat, the deer population has a carrying capacity of 20. What is the population density of deer in the forest?
Population Density= Area/ Population