Brief note on the Concept of Carrying Capacity



In ecology, the thumb rule is that of conserving interrelationships. Human activity that threatens the future existence of other species may be an ecological disaster since it would in turn affect other species also. These interrelationships are taken care of within the concept of carrying capacity. Carrying capacity is a concept which limits the potential ability of natural resources and species to withstand human intervention. It may be described as a test of the ability of land, water and air to keep itself usable and toxicity free despite pollution and effluent discharges and harmful developments over it. The famous American wildlife conservation ecologist Aldo Leopold described carrying capacity in 1933 as a saturation point at which the numbers of a particular species of grazing animals approached the point where grasslands could support no more individuals without a general and continuing decline in the quality of the pasture land.

While chemical fertilizers, insecticides and pesticides increase crop yield, yet their use beyond the carrying capacity of land may destroy crops. This is equally true for the effluent discharges into rivers, ponds and other wetlands. The wetlands sustain life forms and complete ecosystems which in turn support larger ecosystems. Earth's carrying capacity is threatened by monoculture (cultivation of a single crop variety), pollution, overpopulation, overgrazing, deforestation and urbanization. These activities may not be unsustainable in themselves but the thin line that separates them from being beneficial to mankind and becoming harmful is the environmental recognition of the concept of carrying capacity. If taken beyond carrying capacity, the activities may prove disastrous.

Carrying capacity also refers to the number of individuals who can be supported in a given area within the limits of natural resources, and without degrading the social, cultural and economic environment for the present and future generations. The carrying capacity for any given area is not fixed. It can be extended to a certain level by improved technology, but mostly it is changed for the worse by pressures which accompany a population increase. As the environment is degraded, carrying capacity actually shrinks, leaving the environment with no ability to support even the number of people who could formerly have lived in the area on a sustainable basis. No population can live beyond the environment's carrying capacity for very long.

The average citizen's 'ecological footprint' is assessed by the demands an individual, endowed with average amounts of resources like land, water, food, fiber, waste assimilation and disposal, puts on the environment. While, for a citizen in a developed country the land requirement ranges from about 10 to 12 acres (which is an area far greater than that taken up by one's residence and place of school or work and other places where he or she is in those countries), for a citizen in a developing country it is from less than one acre in a sub Saharan country to around three acres in India. A common fallacy is to believe that a rich country can retain the. carrying capacity of its resources in maintaining the standards of their living, by transferring these pressures through trans-national businesses to poorer countries. Since everything is related to everything else, ecological destruction in one country manifests in the form of economic impulsions in other countries. The policy formulators have to think in terms of 'carrying capacity' and not land area. For example, effects of unfettered population growth drastically reduce the carrying capacity in the United States (US) as the unregulated businesses do in India.