Carrying Capacity
Introduced| English |
|---|
| carrying capacity/ˈkæriɪŋ kəˈpæsɪti/ |
| overshoot/ˌəʊvəˈʃuːt/ |
How many can the land hold?
- No environment can support unlimited numbers of a species.
- Food, water, and space always run out eventually.
- There is a maximum population the environment can sustain.
- That maximum is called the carrying capacity.
The carrying capacity
- The carrying capacity 环境容纳量 (K) is the largest population an environment can support long-term.
- It is set by limiting factors like food, water, and space.
- Below K, resources are plentiful and the population grows.
- At K, resources are just enough to hold the population steady.
The carrying capacity of an environment is…
The carrying capacity (K) is the maximum population an environment can sustain with its resources.
Growth slows near K
- Far below K, a population grows fast.
- As it nears K, resources become scarce and growth slows.
- The population then levels off, holding near the carrying capacity.
- This produces the S-shaped logistic growth curve.
Growth toward carrying capacity
logistic growth to capacity K
Growth is fast at first, then levels off at the carrying capacity as resources run low.
What happens to population growth as it nears the carrying capacity?
As resources run short near K, growth slows and the population levels off.
Overshoot and dieback
- Sometimes a population grows past K — an overshoot 超出.
- Now there are too many individuals for the resources.
- Many then die off in a crash, called a dieback.
- The population falls back toward, or even below, the carrying capacity.
When a population grows past its carrying capacity, it is said to ____ the capacity.
An overshoot happens when a population briefly exceeds K; it then crashes back down (dieback).
Food, water, and space are limiting factors that set the carrying capacity.
Limited resources like food and space determine how large a population an environment can hold.
Select all true statements about carrying capacity.
Carrying capacity is a limit, not unlimited. The other three are correct.
Carrying capacity is not fixed forever. If resources increase (a good rainy year), K rises; if the habitat is damaged, K falls. And a population that overshoots K does not stay there — it crashes. Growing past the limit is always temporary and costly.
Deer on an island:
- Deer are introduced to an island rich in plants — their population booms.
- They overshoot the carrying capacity, eating the plants faster than they regrow.
- Food runs out and many deer starve — a dieback that drops the population back below K.
The carrying capacity (K) is the maximum population an environment can support long-term, set by limiting resources. Population growth slows and levels off near K (logistic growth). If a population overshoots K, it crashes back down in a dieback. K can rise or fall as resources change.