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Carrying Capacity

CARRYING CAPACITY

In ecological theory, the carrying capacity (K) of a geographical region, with respect to a particular species, is the maximum population size that the region can support. It is assumed that the birth and death rates are density-dependent, the former declining and the latter increasing as the population size (N) increases and food per individual decreases. Then the population will reach a stable maximum, the two rates intersect, and N = K. When a species is introduced into a region, it will experience a high, unconstrained growth rate. As N approaches K, the growth rate will fall. Thus N follows an S-shaped curve that rises steeply at first and then reaches a plateau with N = K. If the trends in the birth and death rates are linear, then this curve is the logistic function, first described by Verhulst in 1845. The model assumes a closed population (no immigration or emigration), no importation of food, and no improvement in the efficiency of food production. These assumptions are restrictive in the context of nonmigratory human populations, but anthropologists have estimated the carrying capacity for isolated hunter-gatherer tribes. Even where the assumptions hold, it has been observed that many animal species, including homosapiens, restrict their fertility to maintain the population density below the level at which mortality rises.

For the world population as a whole, migration is not an issue. Over the years, several authors have estimated the global carrying capacity based on maximum food production. In 1983, Bernard Gilland calculated a global carrying capacity of 7.5 billion. However, improvements in food production have permitted the world population to reach 6 billion in the year 2000 without any evidence of increase in mortality.

Gerry B. Hill

(see also: Population Density; Population Forecasts; Population Growth; Sustainable Health )

Bibliography

Gilland, B. (1983). "Considerations on World Population and Food Supply." Population and Development Review 9:203211.

Gotelli, N. J. (1995). A Primer of Ecology. Sunderland, MA: Sinaner Associates, Inc.

Weiner, J. S. (1975). "Tropical Ecology and Population Structure." In The Structure of Human Populations, eds. G. A. Harrison and A. J. Boyce. Oxford: Clarendon Press.

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carrying capacity

carrying capacity The maximum population of a given organism that a particular environment can sustain; the K (saturation) value for species populations showing S-shaped population growth curves. It implies a continuing yield without environmental damage. It may be modified by human intervention to improve environmental potential (e.g. by applying fertilizers to range-land and reseeding it with nutritious grasses).

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"carrying capacity." A Dictionary of Ecology. . Encyclopedia.com. 27 Jun. 2017 <http://www.encyclopedia.com>.

"carrying capacity." A Dictionary of Ecology. . Encyclopedia.com. (June 27, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/carrying-capacity

"carrying capacity." A Dictionary of Ecology. . Retrieved June 27, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/carrying-capacity

carrying capacity

carrying capacity The maximum population of a given organism that a particular environment can sustain; the K (saturation) value for species populations showing S-shaped population growth curves. It implies a continuing yield without environmental damage. It may be modified by human intervention to improve environmental potential, e.g. by applying fertilizers to range-land and reseeding it with nutritious grasses.

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"carrying capacity." A Dictionary of Plant Sciences. . Encyclopedia.com. 27 Jun. 2017 <http://www.encyclopedia.com>.

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"carrying capacity." A Dictionary of Plant Sciences. . Retrieved June 27, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/carrying-capacity-0

carrying capacity

carrying capacity Symbol K. The maximum population of a particular species that can be supported indefinitely by a given habitat or area without damage to the environment. It can be manipulated by human intervention. For example, the carrying capacity for grazing mammals could be increased by boosting the yield of their grassland habitat by the application of fertilizer. See also K selection.

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"carrying capacity." A Dictionary of Biology. . Encyclopedia.com. 27 Jun. 2017 <http://www.encyclopedia.com>.

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"carrying capacity." A Dictionary of Biology. . Retrieved June 27, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/carrying-capacity-2

carrying capacity

carrying capacity The maximum population of a given organism that a particular environment can sustain; the K (saturation) value for species populations showing S-shaped population-growth curves. It implies a continuing yield without environmental damage.

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"carrying capacity." A Dictionary of Zoology. . Encyclopedia.com. 27 Jun. 2017 <http://www.encyclopedia.com>.

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