Carrying Capacity
- The maximum number of individuals of a species that an ecosystem can support is known as its carrying capacity
- Carrying capacity is represented by the letter K
- While every individual within a species population has the theoretical potential to reproduce and have offspring that will contribute to population growth, in reality there are many factors that prevent every individual in a population from surviving and reproducing
- This means that the population size of each species is limited, i.e. the ecosystem has a carrying capacity for that species
- The graph below shows the population growth of a population of lions
- The point at which the graph starts to flatten out is the carrying capacity of this population
- At this point the environmental factors that stop all individuals from surviving and reproducing mean that the population can no longer increase
Carrying capacity graph
Carrying capacity is reached when the growth of a population starts to level off
Factors affecting carrying capacity
- Abiotic factors involve the non-living parts of an ecosystem, e.g.
- Light availability
- A lack of light will reduce the carrying capacity for a plant population as it will limit photosynthesis
- Temperature
- Low or high temperatures will influence carrying capacity as this will affect the rate at which the reactions of metabolism can occur
- Soil mineral availability
- Low mineral availability will reduce carrying capacity as it will affect the ability of plant populations to build biological molecules such as proteins and chlorophyll
- Light availability
- Biotic factors involve the living parts of an ecosystem, e.g.
- Competition for resources
- A lack of resources will limit the carrying capacity of an ecosystem
- Energy that an individual puts towards competing for resources will not be available for growth and reproduction, so this will reduce carrying capacity
- Predation
- Energy that an individual puts towards avoiding predators will not be available for growth and reproduction, so this will reduce carrying capacity
- Disease
- Energy that an individual puts towards fighting off disease will not be available for growth and reproduction, so this will reduce carrying capacity
- Competition for resources