Ecological Carrying Capacity

Question 1

What is ecological carrying capacity?

Answer 1

the maximum population of a species that can be sustainably supported within an environment

Question 2

What is homeostatic control of a population?

Answer 2

Populations in the wild do not remain constant in size but instead fluctuate about the carrying capacity and negative feedback keeps it under control

If a population increases or decreases from the equilibrium populations, the environmental resistance will change with it, to result in the opposite change to bring it back to the equillibrium

Question 3

What are some of the factors which stabilise or limit population size or carrying capacity?
Explain them

Answer 3

NUTRIENT IONS IN SOIL - become used up as plant pops increase, so limits population growth

COMPETITION/OVERCROWDING - increases at high densities

FOOD/PREY (OF ANIMALS) - becomes more difficult to get as population increases

PREDATORS - are able to catch/are attracted to higher density prey populations

PARASITES/DISEASE - spread between individuals more easily at high densities/immunity of stressed individuals weakened at high population density

Question 4

What is a plateau/stationary phase of a growth curve a result of?

Answer 4

1. competition/limiting factors for:
   - space
   - named nutrients
   - named respiratory gas
2. microorganism has been poisoned by
   - toxic waste
   - named waste
3. cell division = cell death/division rate slows or equals death rate
4. reached carrying capacity

Question 5

What are the phases on a growth curve?

Answer 5

lag
exponential
stationary
death

Question 6

Give an example of ecological carrying capacity

Answer 6

Elephants in Africa

• Conservation efforts in certain areas of Africa have been so successful that the elephant populations are now well above carrying capacity
• This has resulted in overgrazing, soil compaction, habitat loss, reduced species diversity and exhaustion of food sources
• As human pop density also increased, there has been increasing conflict with farmers as crops are eaten or trampled

In Western Africa, the population in 1980 was 14,000, but fell to 6,000 in 2004.

Question 7

Give an example of wider implications cased by exceeding carrying capacity

Answer 7

1. Population of herbivore is higher than carrying capacity
2. overgrazing/deforestation
3. reduced organic matter
4. decreased fertility
5. increased use of artificial fertilisers
6. increased fossil fuel use
7. increased global warming

So rabbits are causing global warming

Question 8

What are the implications of exceeding carrying capacity?

Answer 8

Can be localised

Or widespread and difficult to connect to the original cause