3.4 - Carrying Capacity

Carrying Capacity

the maximum number of individuals in a pop. that an ecosystem can support (based on limiting resources)

K

Letter for carrying capacity

Theoretical carrying capacity graph

Realistic carrying capacity graph

- Population briefly "overshoots", then die-off happens

Food, water, and habitat (nesting sites, space)

What determines carrying capacity?

Overshoot

when a population briefly exceeds carrying capacity

- ex. Deep breed in fall, give birth all at once in spring. Sudden spike in population = overshoot

resource depletion (ex: overgrazing in deer)

Consequent of Overshoot

Die-Off

sharp decrease in pop. size when resource depletion (overshoot) leads to many individuals dying

- Ex: many deer starve with too many new fawns feeding in spring

Case Study of Reindeer in Alaska

Reindeer of St. Paul Island:

- 25 introduced in 1910

- Growth was gradual (10'-30'), then exponential (30'-37')

- Carrying capacity was overshot

- Sharp die-off lead to pop. crash as food resource (lichen) were severely depleted

resource depletion; collapse

Real populations don't always fluctuate around carrying capacity. If _____________ is severe enough, total population ________ can occur

Carrying Capacity + Predator/Prey Graph

1.Hare population increase due to low predator population (lynx)

2.Lynx population increase due to increase in food (hare)

3.Increasing lynx pop. limits hare pop; leads to die-off

4.Hare die-off decreases lynx food source, leading to die-off

5.Hare pop. increase due to low predator pop. (lynx)