Carrying Capacity in a Ecosystem

Growth Rate and Carrying Capacity

• When a population of a particular species is smaller than the carrying capacity, the population's growth rate increases as births outnumber deaths. When the population is greater than the carrying capacity, the population's growth rate declines as deaths outnumber births. When the population is the same as the carrying capacity for a particular location, the population's growth rate stops changing.

Patterns

• Population growth exhibits two patterns. In one pattern, the population grows rapidly as long as food and habitat are abundant. As resources become scarce, the population decreases as birth rates slow and death from competition for food increases. As the growth rate nears zero, the population stabilizes as it approaches carrying capacity.

  In the other pattern, a population increases rapidly until it is so large that it can not be sustained. When it reaches this point, its size is decreased by disease and predators. When resources increase, the population grows again.

Humans

• When applied to humans, carrying capacity refers to the number of individuals Earth can sustain at different standards of living. The population that can be sustained if everyone achieves the standard of living in the United States is smaller than the number that could be sustained if everyone maintains the standard of living found in developing nations. However, applying the concept to humans is difficult because humans can change their environment with technology.