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Features >> April 17

Population Expansion and Ecological Impact (With With (With Reference to Manipur)
By B. Manihar Sharma

Introduction:

The uncontrollable growth of human population at the rate of 93 million per year during 1984-1995 has caused a number of socio-economic and ecological problems in both the developed and developing nations of the world. The gain production of the world fell sharply from 1,800 million tons during 1985 to 1,400 million tons by 1990. The rapid increase in human population has been directly or indirectly responsible for the environmental disaster faced by us now. The emissions of carbon monoxide and carbon dioxide into the atmosphere is estimated at 7.1 billion tons per annum of which burning of fossil fuels liberate 5.5 billion while the remaining 1.6 billion are produced from the enormous removal of forest throughout the globe. Investigations of the impact of man's activities on the different terrestrial and aquatic ecosystems in the tropical, subtropical, temperate and mountain zones of the world were undertaken in the multidisciplinary Man and Biosphere (MAB) program launched by the UNESCO in 1974. Besides analyzing the various effects of increased human activities on the earth resources, the MAB program has also been finding out feasible ways and means towards the management and conservation of the resources so that production is maintained on a sustainable basis. The need for protecting the natural resources as well as enhancing agricultural and fish production to meet the demands of the increased human populations were emphasized in Agenda-21 of the Earth Chapter of the United Nations Conference on Environment Development (UNCED) held in Rio-Janeiro during 1992. The environmental deterioration going inversely with economic and technological growth, in fact varies directly with the population growth of the human beings on the earth.

Population Scenario:
The current population of the world is estimated at 5.5 billion by 1991 growing at the rate of 1.7% annually. While the growth rate was found highest in 1965 (2%), a gradual decreasing trend has been noticed by 1982 (1.8%) and the doubling time has been estimated at 41 years. In 1998 the birth rate of the world was 2.8% per year with the death rate at 1%.(World Watch Institute 1998). But, the growth rate varies significantly from region to region. According to Daily and Ehrlich (1996) the population in the developing countries grow at the rate of 2.4% annually with the estimated doubling time of 30 years whereas in the developed nations the growth rate is estimated at 0.5% annually with the associated doubling time of 137 years. Hence in the developing countries the growth rate is found to be 4-5 times the growth rate in the developed countries. The rise in population in Asia including India is much alarming (3 billion in 1988 constituting 60% of the world population). The trend in India is also found to be much alarming with the population reaching 846.3 million in 1991 and 953 million by 1996. With the annual growth rate of 1.8%, the doubling of population in India is expected by 2031 A.D. In 1988, the World Bank calculated population projections at stationery phase for a few selected countries of the world. The ratio of the projected population to the 1988 population was found to be in the highest range in Kenya (5.3) and Ethiopia (4.3). India belonging to the low range 2.1 to 2.5 records the lowest ratio as compared to Mexico, Philippines and Peru (World Watch Institute 1989). Bangladesh, Iran, Pakistan, Sudan and Zaire have intermediate ratios (2.6 - 4.30).

Environment Effects:
Besides causing typical socio-economic problems, rapid expansion in human population has produced a number of deleterious effects to the environment and natural resources of the biosphere. These problems are found to be more serious in the developing countries as compared to the developed countries. Some problems worth noting are found in Africa (37countries) and Asia (16 countries) where the forests has degraded to a great extent. The afforestation by deforestation ratios in these countries range from 1:4.5 to1:29 as against the world average 1:10(Newman 1990). The consequence is that the fuel wood requirement per capita at the rate of 0.45 cu.m. per annum cannot be met with. In the present state of affairs, it is predicted that approximately 2,400 million people of the world would be facing wood starvation by 2002 A.D. and there would be an overall deficit of 960 million cu.m. of fuel wood by then. In India some states viz. Arunachal Pradesh, Bihar, Himachal Pradesh, Manipur, Maharashtra, Meghalaya, Mizoram, Nagaland and Orissa have higher deforestation rate as compared to other states and afforestation by deforestation ratio in these states range between 1:14 and 1:17 ( Sharma 1997). As compared to the forest loss indices of the countries of the world (Thomas et al 1996), some regions of India viz. the North-East, Gujarat, Bihar, Madhya Pradesh, Maharashtra and Orissa have high forest loss indices above 0.04 ( Sharma 1997) and as such these regions have been identified as areas of critical concern in India.

Due to the immense pressure of the expanding human population, many of the pristine areas of the world are depleted at an alarming rate. Studies towards analyzing anthropogenic threats to biodiversity based on species diversity, habitat use as well as forest loss and human demographic trends have been made by a number of ecologists (Mayers 1990, Thomas et al 1996, Daily and Ehrlich 1996). Thomas et al ( 1996) have computed the population pressure index of the countries of the world ( Table 1) by combining the human population density of a region in a particular year by the corresponding rate of population increase . Countries having high index of population pressure obviously exert great stress on the biodiversity and the resources, often threatening the same to extinction. Bangladesh having the highest index in the world is followed successfully by Rwanda, El Salvador, Lebanon etc. India with an index of 5.37 holds the 8th rank and is followed by South Korea, Philippines, Pakistan, Vietnam etc. With regards to the degree of pressure on biodiversity by a huge population size coupled with the characteristic of exhibiting mega diversity and regional hot-spots, Taiwan, India, Philippines, Vietnam, Sri Lanka and Nigeria have been identified as countries of critical concern ( Table 1). These countries would require measures for successful strategies towards conservation of biodiversity resources. 

To assess the degree of pressure exerted to the natural systems by the increased human population, indices of population pressure of different regions of India have been assessed following the equation given by Thomas et al (1996). The indices have been computed by combining the population data of 1991 and rate of population increase derived from the decadal growth rate of 1981 - 1991. It is evident from Table 2 that West Bengal, Uttar Pradesh, Bihar, Kerala, Haryana, Dadar & Nagar Haveli have exhibited high indices of population pressure which are much comparable with the high indices of countries like Bangladesh, Rwanda, El Salvador and Lebanon. It is emphasized that exceptionally very high indices by passing the maximum value of population index of the world, have been observed in Delhi, Chandigarh, Pondicherry, Lakshadweep, Daman and Diu. Top priority may be given for successful conservational measures to protect the biodiversity resources of these areas as the resources might obviously have been subjected to great stress by the overwhelmingly large population densities. A list of identified areas of critical concern in India suffering from one or more threats such as possessing low afforestation rates, high deforestation rate, high forest loss index and high index of population pressure is given in Table 3. Out of areas in the list, special attention may be given to those which have been subjected to higher stress from one or more factors mentioned earlier. In this context, it may be noted that North-East India, Bihar, Chandigarh, Delhi, Orissa and Pondicherry would highly require necessary conservational measures and recovery processes to combat the threats to biodiversity and the natural resources. 

Table 1: Human population pressure in some countries of the world. (adapted from Thomas et al 1994)

Table 2: Population pressure in the different regions of India 

Table 3: Region of critical concern in India from environmental perspectives 

The strategy of population pressure in the highest ranging from 363 - 576 .
These three different districts of Manipur has been assessed as per the census of 1991 and have got higher indices of population pressure ( 9.8 - 15.5). 

Imphal, Thoubal and Bishnupur districts as compared to others (table 4). 

The major impact of human population pressure in Manipur has been on the forest resources. The fuel wood production of the state has decreased from 70,264 cu.m. in 1986 to 24,958 cu.m. in 1990. The per capita availability of fuel wood has also reduced significantly from 0.03 cu.m. 91981) to 0.013 cu.m. (1991). While the annual ratio of afforestation by deforestation in the State bypasses those of India and the World average, serious threats to the survivability of the species has been evident as over 60 species of trees, shrubs, orchids, grasses and medicinal plants including 12 endemic species at the minimum have been reported as threatened species (Sharma, 1997) under the forest canopy alone.

According to the report of the World Watch Institute, (1989), the rain-fed crop
plants and irrigated lands of the world have been degraded to the extend of 335
million ha. (59%) and 40 million ha. (31%) respectively. Similarly over 3100 million ha. (84%) of range lands have been degraded due to exploitation by the ever increasing human population with the increase of fertilizers used in the fields from 5kg (1950) to 24kg (1989) per person, it is alarming that the per capita grain area has significantly decreased from 0.23 ha. in 1950 to 0.12 ha. by 1989.

With the tremendous pressure from the increases in human population, 50% of the wetlands of the world have been lost due to the conversion into agricultural
lands. 54% of the wetlands in the USA, 40% coastal wetlands in Britain, 80%
wetlands in west France, 70% in Portugal and 90% wetlands in New Zealand have been lost through the use for agricultural and industrial developments (Dugan 1994). The consequences of these practices are multifarious viz. reduction in fish harvest, decreases in biodiversity, increase in salinization, decrease in fertile top soil etc. With the loss of the wetlands the cycling of nutrients in the biosphere is significantly affected and this upsets the hydrological (water) cycle of the world (Finlasyon and Moser 1991, Dugan 1994).
While we are all aware of the important environmental consequences of the fast
increases in human population, the ecologists are much concerned with the study of the feasible measures of these impacts. One important measure is to assess the portion of the terrestrial net primary production (basic source of energy for all animals) which is directly consumed, utilized as well as eliminated from the biosphere due to human activity. It is estimated that about 40% of the total net primary production of the world has been consumed by the human population.

To assess the impact (I) of the population of the environments, 3 characteristics i.e., affluence or per capita consumption (A), population size (P) and environmental damage T =PAT (Ehrlich and Ehrlich 1990, Daily and Ehrlich
1996). As per this estimation each inhabitant of the rich nations does
approximately 7.5 times more damage to the biosphere as compared to an
inhabitant of the poor nations (developing countries). As pointed out by Daily
and Ehrlich (1996), the United States of America population exerts a larger
impact to the earth's life support system as compared to any other nations in
the world.

Conclusion:
Though we may be consoled to a certain extent that the average human growth
rate has gone down significantly over the last ten years, we have to admit that
the current trend of population increase in many developing countries still
conforms a steep, in essence an exponential curve. In essence, as postulated by the experts, the population of the world is expected to double again in 2050 A.D. As there is enough evidence that population growth itself is a block to economic development, environmentalists like Revelle and Revelle (1992) have given the suggestion that available funds in the respective countries and nations must often be spent on short-term needs - medical care, food disaster relief- rather than long -term investments such as roads, industrial developments etc. On the environment front, people are the primary agents for polluting the environment and degrading the ecological resources. Many human activities, from dam building and skyscraper construction to forest clearance and dredging and canalization of water courses have confirmed that human beings are allogenic engineers which alter the physical environment and modulate flow of resources to other species (Clive et al. 1996). The key factor for the survival of the biosphere is to curtail and stabilize the population of the world at an appropriate level as well as to make the people aware of the rational use and conservation of the natural resources and work out a successful strategy to restore a safe and sound environment free from the doldrums and uncertainties existing today.

Reference:

Clive G.J., Lawton J.H. and Sanchak M. (1996).
Organisms as Ecosystem engineers. In Samson F.B. and Knoop F.L. (Eds) Ecosystem management: Selected Reading. Springer Verlag, New York. p.130-147.

Daily G.C. and Ehrlich P.R. (1996). Population, Sustainability and Carrying. In
Samson F.B. and Knoop F.L. (Eds) Ecosystem management: Selected Readings, Springer Verlag, New York. P.435-450.

Dugan P. (1994). Wetlands in danger. IUCN. Mitchell Beazley, London.

Ehrlich P.R. and Ehrlich A.H. (1990). The population Explosion. Simon and
Schuster, New York.

Finlayson M. and Moser M.E. (1991).Wetlands. Facts on Files, United Kingdom.

Meyers N. (1990). The Biodiversity challenge: Expanded hot-spot analysis.
environmentalist10:243-256.

Newman a. (1990).Tropical rain forest. Eddision-Sadd, New York.

Revelle P. and Revelle C. (1992).The global Environment: Securing a sustainable
future. Jones and Barlett Boston.

Sharma B.M. (1997).Whence the forest Biodiversity? In souvenir: Eight Manipur
Science Congress. Manipur University, Imphal p.49-62.

Thomas D.Sisk Launer A.E.Switky K.R. and Ehrlich P.R. (1996).Identifying
extinction threats. In Samson F.B and Knopf F.L. (Eds).Ecosystem management: Selected readings. Springer Verlag, New York, p53-68.

World watch Institute (1989) Linda Starke (Ed).State of the world: Report on
progress towards a Sustainable Society. Norton W.W and Company, New York and Prentice hall of India, New Delhi.

(The author is a Professor in the Department of Life Sciences, Manipur University, Imphal, Manipur)