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Tuesday, March 23, 2010

Social Dimensions of Environment

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The Social Dimensions of environment incorporate - Demographic Pattern, Life styles of people, Human Health and Habitat, and Social Interactions among organisms.

Demographic Pattern
The Demographic Pattern relates to the growth of human population, its density and distribution, life expectancy, birth rate and mortality. It is due to the planned economic development that India has become able to manage its growing population.. It is the world’s second populous country with a population around 95 crores. It supports about 17 percent of the world’s population on just 2.4 percent of the world’s land area.

The demographic dimensions of the social environment include urbanisation, urban congestion, growth of slums, over encroachment of government buildings and monuments, plans and strategies of social development, migration of people due to hazards and mega projects, rehabilitation programmes etc.

Due to rapid urbanisation notable movement of refugees and displaced persons has been recorded over past 30 years. At the end of 20th century the number of people living outside their own country was estimated to be 150 million.

Life Style of People
The life style relates to the ways of living of people of a country. The life style of the people across the globe and in India also, has changed over the years and their life standard has also gone up considerably. The household consumption expenditure in India has moved from food to clothing, rent, furniture, furnishing and recreational activities. The dimensions of life style cover education, supports from government sectors, care of old people, social security for people, eradication of poverty etc.

Human Health and Habitat
This dimension relates to sanitation, provisions of facilities to people, access to basic health facilities, spread and control of diseases and irradiation of key problems that pose challenges to Indian societies. Health dimensions also include-
(a) Contribution of environmental factors to health problems,
(b) Primary healthcare, mother and child healthcare, need of social health in development sectors,
(c) Formulation of public and environmental health policies, Legislations, and standards, consumerism and consumer education,
(d) Strengthening of health surveillance, early alert and rapid response mechanism at district, block and Panchayat levels.

Habitat dimensions relate to housing of people and provisions of basic services and amenities. These dimensions also cover-(a) Good sanitation and uncontaminated water supply,(b) Facilities of drainage, liquid and solid waste management, (c) National Housing Policy,(d) Formulation of legislation for the protection of natural environment; its flora, fauna and abiotic resources.

Social Interactions among Organisms
The social dimensions include interactions also that go on among organisms continuously in different ecosystems. The social interactions have been grouped into Positive and Negative interactions. Positive interactions include mutualism, commensalisms, amensalism and protocooperation. Negative social interactions include exploitation, predation, antibiosis and competitions.

A. Positive Interactions

(i) Mutualism: The social relationship between two species in which both the species derive benefits from each other, is called as mutualism. Pollination by animals; dispersal of fruits and seeds by birds, insects and even by human beings; symbiotic associations in Lichens etc. are some examples of mutualism.

 Lichen is an association of an alga and a fungus. The alga synthesizes food as it is blessed with chlorophyll but fungus can only live on the food prepared by the alga. In return it offers protection, moisture and nutrients to the alga. Such an association is called as symbiosis.

There are symbiotic nitrogen fixers also. The bacterium Rhizobium lives in the root nodules of leguminous plants. It receives food from the leguminous plant and in turn it fixes atmospheric nitrogen for the host plant.  Non- leguminous plants of about 400 species have been reported to have symbiotic associations through their leaves.

Rhizobium live in the root nodules of leguminous plants

(ii) Commensalism: The social relationship between two species of organisms in which one species is benefited but no one is harmed, is called as commensalisms. Sheltering of birds and animals on trees; presence of the bacterial species E. coli in human intestine; Lianas; and epiphytes like Orchids, banyan plants, peepal plants and Loranthus etc. exhibit commensalism.


Epiphytes are green plants that grow on other plants but do not harm to their hosts. The Lianas are vascular plants rooted in soil but stand erect by the support of other plants. These are very common plants in the dense forests of moist tropical climates.

(iii) Protocooperation (non-obligatory mutualism): An association of members of two populations, in which both are benefited, is called as Protocooperation. An important example of this association is the association of the Sea- anemone and the Hermit crab. The crab carries the sea-anemone to the fresh feeding sites where as it gets protection by the sea – anemone, though this is not always necessary.

 Sea-anemone and Hermit crab.

B. Negative Interactions
            (i) Exploitation: In nature, it has been observed that organisms of one species harm the organism of other species by taking support, shelter and by exploiting food from the other species. Under these conditions relations between species are differently called as Parasitism and Predation. We have already discussed this relationship in earlier paragraphs. In predation an animal kills its prey for food, but a parasite derives its food from the host and does not kill it. The host may die due to some disease caused due to the parasite.  
(ii)Amensalism: The association between organisms of two different species in which one is inhibited or destroyed and the other is unaffected, is called as amensalism. There are two modes of amensalism (a) competition and (b) antibiosis

(a) Competition: The relation which involves struggle among organisms for water, nutrients, space, sunlight or organic food is called as competition. Competition may either be Interspecific or intraspecific. The Interspecific Competition occurs between members of the same species due to overcrowding or overpopulation. Intraspecific Competition occurs between members of different species. It is also called as contest or interference competition. This type of competition has been reported in cases of insects, paramecia etc.
(b) Antibiosis: Secretion of substances by the organisms of one species to kill or repel another organism of a different species is called as antibiosis. Species of Actinomycetes (bacteria) and some Lichens have been reported by researchers to produce substances inhibiting certain fungi and bacteria. The classic example of antibiosis is the destructive effects of the mould Penicillium upon certain bacteria.. The secretion, known as Penicillin has remained a potent medicine in combating bacterial infections in early days of antibiotic discoveries.

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