Growth of human population and its impact on natural environment

>> Tuesday, March 30, 2010

The human population refers to the total human inhabitants of a specified area, such as a city, a country, a continent or the world, at a given time. The study of human population as a discipline is known as Demography and one who studies population at the advanced stage is known as a Demographer.The demography, as a subject of study is an interdisciplinary field which involves mathematics and statistics, biology, medicine, sociology, economics, history, geography and anthropology. It is concerned with the size, composition and distribution of populations along with patterns of changes of populations overtime through births, deaths and migration; and the determinants and consequences of such changes. Studies of population are important particularly for governments for planning in the field of health education, housing, social security, employment and preservation of environment. Demographic studies provide information which is needed to formulate population policies of governments as governments are concerned to modify demographic trends so as to achieve the objectives of economic and social developments.
The population of the world grew at an alarming rate since 1650 to 1950 and onwards. The unprecedented surge in population has caused and is still causing rise in individual consumption of food, water, and exploitation of natural resources like land, water, fossil fuels, minerals, vegetation etc. The combined effects of population growth, consumption, overuse, wastage and misuse of resources has strained the capacity of the earth to sustain life. That’s why the study and control of human population is very important today. In this lesson we are going to study the impact of growth of human population on environment in particular.
 Social Impacts of Population Growth
Explosive growth in human population causes a number of serious problems like food-scarcity, over crowding, poverty, increasing consumption, encroachment on monuments, stress on common social facilities, stress on civic services etc.
A. Food Scarcity: The population growth leading to population explosion causes severe economic disparities and gives birth to - competition for resources, price rise, hunger, malnutrition, and mass starvation.
The gap between the rich and the poor has increased due to population growth. The rich people are exploiting more resources than poor people. Malnutrition is one of the most common effects of these problems. The poorest people in developing countries do not get adequate calories to develop their health properly. In Ethiopia, almost half of all children under age of 5 suffer from malnutrition. Most poor children and adults suffer from severe vitamin and mineral deficiencies. These deficiencies cause failure of senses, mental disorders and damage to vital organs. There are millions of starving people through out the world. As per estimates, from 5 to 20 million people die of starvation across the world, every year.
B. Overcrowding: There is limited habitable place on the earth. The overpopulation has caused severe stress on land which has further stressed forests and agricultural areas.
People are migrating towards cities in search of jobs and cities are becoming overcrowded. Semi-urban lands and cultivable lands near cities have already gone under construction of houses. Even government lands like railway platforms, areas around monuments, and parks etc. are being seriously encroached. Increasing crowd in cities is aggravating the problem of pollution and insanitation leading to the spread of epidemics. Green lands in urban areas and even sea beeches have been reclaimed for housing and industrial purposes.
C. Poverty: Conditions of having insufficient resources or income are called as poverty. In its extreme form, poverty is the lack of the basic human needs like food, clothing, housing, drinking water, and health services. The world’s poorest people are found in Africa, Asia, Latin America, and Eastern Europe. They always struggle for shelter and clothing. They often suffer from malnutrition, famine, disease outbreaks, epidemics and war.
In developed countries, poverty has caused drug dependence, crime, and mental illness. Overpopulation, unequal distribution of resources, inability to meet the cost of living, inadequate education and employment, degradation of environment, demographic trends and welfare incentives are primary causes of poverty. Lives in developing countries represent a picture of misery, hunger and poverty. Many of these countries have entered the second stage of Demographic Transition in which a high birth and reduced death rates along with a rising life expectancy accelerates the population growth.
D. Increasing Consumption: It is a simple truth that more people consume more food, wear more clothes, drink more water, need more houses to live, need more medicines for cure, make more noise, create more pollution, generate more waste etc.
Some countries of the world have nearly stabilized their population but their life style has become consumption based. We may take the example of United States of America. Though, it is not overpopulated, it consumes about 40% of resources of the world alone and produces not less than 21 % of the world’s carbon dioxide which is a green-house gas.
It has been observed by ecologists the world over that powerful people and developed nations consume more resources than weak and poor people and developing or under developing countries. Thus, increase in the rate of consumption at one end is causing an increase in hunger and crime at the other end. Merely, 20% of the world’s population lives in developed and richest countries. According to United Nations the world’s richest 20% of population consumes about 86% of resources of the world. Thus, the population growth and the changing pattern of consumption are responsible for the severe stress on environment.
 E. Encroachment on Monuments   : A monument is a building, column or statue of historical importance built-in the past to remind future generations about a famous person or event. People who migrate from rural areas and work in cities often face difficulties and most of them spend their nights as homeless. They take shelter on pavements, abandoned railway buildings and on spaces left around historical monuments. Gradually, they build temporary houses on those places and start keeping their families there. Some of them start business works on those places and gradually a colony of such persons is established. So is happening with most of our uncared monuments today.
Most of our monuments and old government buildings are being badly encroached by people who after sometime try to become owners of those areas. This is illegal and criminal attitude. However, this condition is the by-product of the explosion of population.
F. Stress on Common Social Facilities: We need facilities and facilities both on home front and on social front. More people require more use of available facilities. But facilities may be limited. So, there may be a great rush and competition for availing facilities causing severe stresses on those facilities. Community Halls, Bus Stops, Railway Junctions, Parks, Play Grounds, Hospitals and even roads are some common social facilities that are facing heavy stresses due to population explosion. One can see long lines of people standing for hours for their works. There is heavy traffic on roads round the clock. All these social facilities are often heavily polluted due to careless practices of human beings.
G. Stress on Common Civic Services: Services provided by municipalities or municipal corporations to civilians are called as civic services. Those services include cleanliness, water supply, waste disposal, maintenance of drainage systems, community health care, care of animals (dogs and cattle) on roads, basic education etc.
Over population has caused severe stress on civic services. It has excessive load of work on bodies providing civic services. As a result, those services have become unable to perform properly. On the other hand, many people in our societies have lost civic sense. Some of them drop their domestic wastes (including plastics) into drains or throw away garbage on roads. Some persons draw most of the supply water through electric pumps and all the other inhabitants of the area go without water.
Ecological Impacts of Population Growth
The scientific study of inter-relationships among organisms and between organisms, and all aspects- living and non-living, of their environment is called as Ecology. Thus ecology relates to environment and ecological impacts of population means impacts of population on environment and its various components
The Ecological Impacts of population growth includes - impacts of population growth on Physical and Biological components of the natural environment.
A. Impacts of Population Growth on the Physical Environment
Physical environment means – non living environment or the land, air, water, soil and minerals. The utilization, overuse and misuse of physical resources increased manifold due to the growth of human population. As it has been told earlier, more population means more mouths to eat food which requires more agricultural production. More agricultural production demands two things – (i) more cultivable land, and (ii) advanced agriculture. More cultivable land has been made available by clearing forests and by reclaiming wet lands, ponds and green belts. Advanced agriculture requires utilization of more water, more fertilizers and more pesticides. Application of fertilizers and pesticides makes the soil infertile. Clearing of forests has its own serious impacts and the environment on the whole gets imbalanced.
More population means more space to construct houses and availability of more consumer goods. It also requires more means of transport, more consumption of fossil fuels and more pollution of air, land and water. Thus growth of population leads to pollution of air, land and water. Different types of pollutions are causing a number of problems in the physical environment that are further affecting the biological environment seriously.
B. Impacts of population growth on biological environment
The population explosion of earlier days and of present day also, has already caused and still it is causing serious impacts on the global environment. As for biological environment, Human Population has stressed most of the biological systems, comprising flora and fauna as well as biological diversity.
Ecosystem is the smallest unit of the biosphere. Since most of the components of the physical components are under serious threat due to population explosion, all the biological components are bound to suffer the consequences. And, hence most of the natural processes have been altered seriously that have caused serious imbalances in ecosystems. Let us have some glimpses of these imbalances-
  1. For expanding cultivable land, forests have been cleared on large scales. Illegal timber trade by timber mafias and local pressure for fire wood have further depleted our forest resources. These destructive activities of human being have driven away many species of wild animals and have caused extinction up to considerable level. Forests have also been cleared for setting up of industries and for urbanisation. Thus habitats of varieties of birds, and other animals have been destroyed through human activities. There are other reasons of forest destruction also. Some of those reasons are forest fires and Jhooming. Jhooming is the practice of growing crops after clearing forest land by burning the vegetation. It is also called as slash and burn cultivation. Intensive agriculture and mining have also caused large scale destruction of habitats.
  2. Frequent water crises in many parts of the world caused failure of agriculture leading to hunger and starvation. Vast varieties of plants and animals have been killed due to water crises. Frequent water crises often lead to migration of people and animals to other places thus causing overload on the resources of those areas.
  3. Poaching and killing of wild animals and illegal trade in their body parts have already caused extinction of several species of animals.
  4. Generation of waste due to increasing consumer culture and population explosion is causing spread of serious epidemics and deaths of people in many parts of the world.
Habitat destruction and overexploitation of resources etc. induced by population growth has caused serious depletion of biodiversity in many parts of the world. Bio- diversity is the species richness in a particular area and its depletion causes serious losses of a number of factors that are vital for running up of ecosystems.
Key Words:  human population ,Demographer,health education, housing, social security, employment,Explosive growth,hunger, malnutrition, mass starvation, increasing consumption, encroachment on monuments, stress on common social facilities, stress on civic services,Demographic Transition,pollution, Jhooming, poaching and killing, destruction of habitats,water crisis,epidemics


Mimosa pudica and its applications in traditional healthcare systems

Mimosa plant is a short lived evergreen shrub which can be treated as an annual plant. This is an interesting plant due to peculiar movement of its leaflets that are sensitive to touch. Its fern like leaves close up and droop down whenever touched either by hand or by any object, living or non-living. It is due to the specific characteristics of its leaves that mimosa is regarded as a plant of high ornamental value. These leaves open in a very short time after the stimulus is withdrawn.
Mimosa belongs to the taxonomic group Magnoliopsida and family Mimosaseae. In Latin it is called as Mimosa pudica Linn. Its other names are Betguen Sosa (Guam); Memege (Niue); Mechiuaiu (Palau); Limemeihr (Pohnpei); Ra Kau Pikikaa (Cook Islands). The Chinese name for this plant (Chinese: 含羞草; pinyin: hánxiū cǎo) translates to "shyness grass". Its Sinhala name is Nidikumba, where 'nidi' means 'sleep'. Its Tamil name is Thottal Sinungi, where 'Thottal' means 'touched' and 'Sinungi' means 'little cry'. Other non-English common names include Makahiya (Philippines, with maka- meaning "quite" or "tendency to be", and -hiya meaning "shy", or "shyness"), Mori Vivi (West Indies), and mate-loi (false death)[citation needed] (Tonga). In Urdu it is known as CHui-Mui. In Bengali, this is known as 'Lojjaboti', the shy virgin. In Indonesia, it is known as Putri Malu (Shy Princess). In Myanmar (Burma) it is called 'Hti Ka Yoan' which means "crumbles when touched". It has been described as “sparshaat sankochataam yaati punashcha prasruta bhavet” -a plant which folds itself when touched and spreads its leaves once again after a while. 

Image:1- Mimosa pudica

Image:2 - Mimosa pudica with inflorescence ( drooping leaves are also seen in the image)

Habit and Habitat
The plant, mimosa, though indigenous to northern hemisphere, can be seen every where in the world. First described in Brazil the plant is adapted to different types of soils and prefers open sunny positions. Berneby (1989) has reported that there are at least three distinct varieties of Mimosa pudica out of which M.hispida is uncommon in Americas but it is established in the Philippines, the Caroline and Mariana, Queensland, India and African savanna country. According to the same author, it is M.pudica unijuga that is common in Hawaii and in other Pacific countries where it is regarded as a major weed. Holm et al. (1977) report M. pudica to be a widespread weed in the Caribbean, but far less important to the north and south of this region. This suggests that it evolved elsewhere in the Americas and has not been accompanied into the Caribbean by its full suite of natural enemies.

Since it has an ability of fixing atmospheric nitrogen, it grows well even in nutrient deficient soils. It prefers medium exposure of light. This plant is difficult to transplant due to its sensitivity to root- disturbances. It can not tolerate water logged conditions and dislikes over watering. It is commonly found in rather moist waste ground in lawns, in open plantations, or in weedy thickets. It forms a dense cover on the ground and prevents reproduction of other plant species.

Image:3 - Mimosa pudica with plant associates

(Please click to enlarge these images)
Mimosa pudica is common in rather moist waste ground, in lawns, in open plantations, and weedy thickets.  It forms a dense ground cover, preventing reproduction of other species.  It is a wild land fire hazard when dry. There have been researches which show mimosa pudica to be a herbal medicine but it hasn't proven itself to be able to treat anything- pharmaceutical companies are still researching its properties and uses.  In many places, Mimosa Pudica is becoming a noxious weed, and it can be controlled with various chemical herbicides such as dicamba.  Mimosa pudica is also a host to parasites such as Cochineals insects, one gets rid of the insects by progressively removing them using a cotton stem soaked with alcohol, but if the insects are too numerous, one much sacrifice the sensitive plant and to not re-use the ground nor the pot on which it was cultured. 

Weed Status
Holm et al. (1977) have reported that Mimosa pudica is a weed in about 22 crops in 38 countries. It is commonly seen in waste lands, lawns, pastures and along road sides. It is a serious weed in maize, sorghum, sugarcane, tea, upland rice, soybean and cotton in Southeast Asia. Since it is a shade tolerant weed it commonly grown in plantation crops like coconut, banana, papaya, coffee, oil palm and citrus. Holm et al. (1977) have further reported that its dense growth in tropical pastures its dense growth deters animals from feeding on suitable forage mingled with it. While the plants do not live long--generally a single growing season--the seeds they drop take root easily; Mimosa pudica can become invasive if not kept under control. They are considered weeds in agricultural settings such as forest plantations, farms, orchards and pastureland.

General morphology of the plant
Mimosa pudica was first formally described by Carl Linnaeus in Species Plantarum in 1753.Mimosa is usually a short prickly plant with its branches growing close to ground. It grows up to a height of about 0.5m and spreads up to 0.3m.The stem of mimosa is erect, slender, prickly and well branched. Leaves are bipinnate, fern like and pale green in colour with a tendency of closing when disturbed. These are quadri-pinnate, often reddish, leaflets 15 to 25 pairs, acute, bristly, usually 9 to 12 mm long and 1.5mm wide. Flowers of this plant are axillary in position and lilac pink in colour usually occurring in globose heads. Calyxes are companulate, and petals are crenate towards the base. Flowering occurs from August to October in Indian conditions. Fruits of mimosa are pods, 1.5 to 2.5 cm long, falcate, and closely prickly on sutures.

Applications of M. pudica in Traditional Healthcare System
Ayurveda has declared that its root is bitter, acrid, cooling, vulnerary, alexipharmic, and used in the treatment of leprosy, dysentery, vaginal and uterine complaints, inflammations, burning sensation, asthma, leucoderma, and fatigue and blood diseases. Unani Healthcare System its root is resolvent, alternative, and useful in the treatment of diseases arising from blood impurities and bile, bilious fevers, piles, jaundice, and leprosy etc. Decoction of root is used with water to gargle to reduce toothache. It is very useful in diarrhea (athisaara), amoebic dysentery (raktaatisaara), bleeding piles and urinary infections. It arrests bleeding and fastens the wound healing process. It is mainly used in herbal preparations for gynecological disorders. It has been said to have medicinal properties to cure skin diseases. It is also used in conditions like bronchitis, general weakness and impotence. It is also used to treat neurological problems. The content of M.pudica has a capacity of arresting bleeding and it fastens the process of healing of wounds. It is recommended in diarrhea, amoebic dysentery and bleeding piles. It is also used in herbal preparations of gynecological disorders. Its extract can cure skin diseases. Some herbal doctors recommend it for bronchitis, general weakness and impotence. All the five parts of the plant (that is the PANCHANG) - leaves, flowers, stems, roots, and fruits are used as medicines in the traditional healthcare systems. In India, different parts of the plant have been in popular use for treating various ailments since long. Recent researches show that the extract of this plant can be used for checking child birth. Some authors have reported that this herb can replace contraceptive pills if researches are done properly.

According to different researches done so far, Mimosa Tenuiflora bark is used to relax the mind, and relieve depression, mental distress, irritability, severe palpitations, and amnesia. It is a mood enhancer and improves circulation of the blood. Some believe Mimosa can reduce the onset of baldness. Due to its ability to promote healthy cell growth, Tepezcohuite is used in shampoos, creams, capsules, and soaps. In Ayurvedic and Unani medicine, Mimosa pudica root is used to treat bilious fevers, piles, jaundice, leprosy, dysentery, vaginal and uterine complaints, inflammations, burning sensation, fatigue, asthma, leucoderma, and blood diseases. In Western medicine, Mimosa root is used for treating insomnia, irritability, premenstrual syndrome (PMS), menorrhagia, hemorrhoids, skin wounds, and diarrhea. It is also used to treat whooping cough and fevers in children, and there is some evidence to suggest that Mimosa is effective in relieving the symptoms of rheumatoid arthritis. All parts of the Mimosa plant are reportedly toxic if taken directly. Its consumption is not recommended to pregnant or nursing ladies. Due to these reports, it seams to be best to consult a physician before using Mimosa internally. Researches regarding safety in young children or those with severe liver or kidney disease have not been found.

Principal Constituents of Mimosa plant
M.pudica contains Mimosine which is a toxic alkaloid. Adrenalin like substance has been identified in the extract of its leaves. Some workers have reported the presence of Crocetin dimethyl Easter in the extract of the plant. Roots contain tannin up to 10 per cent. Seeds contain a mucilage which is composed of d-xylose and d-glucuronic acid. The plant extract contains green yellow fatty oil up to 17 per cent. The plant is reported to contain tubuline and a new class phytohormone turgorines is found to be active in the plant. The periodic leaf movement factors are reportedly the derivatives of 4-o-( b-D-glucopyranosyl-6-sulphate) gallic acid3.

Key Words: Magnoliopsida, Mimosaseae, touch, Brazil, Caribbean, root- disturbances, Carl Linnaeus, Species Plantarum, panchang, urinary infections, premenstrual syndrome (PMS), rheumatoid arthritis, toxic, contraceptive, leucoderma, pregnant ladies.


The innovation that was done fifteen years ago ...

>> Sunday, March 28, 2010

The world House Sparrow Day, March 20 has just passed. Thanks to the organisations that joined hands for a noble cause and initiated international awareness and conservation campaign for the protection of the small house bird that had been living with human civilization since the remote past or probably since the emergence of the human civilization.

I wish to thank Md. E. Dilawar of BNHS (Bombay Natural History Society) who has been working for the cause of sparrow conservation for more than five years and congratulations to him for becoming head of the Government sponsored three year long  project for sparrow conservation being implemented by India’s fore running organisation that is, and that has been attached with a number of good names since its formation. Again I hereby wish to congratulate Mr. E. Dilawar for receiving the award from Time for the year 2008.

Hard effort and tiresome researches had once already been done on the conservation of birds under a project entitled “Bird Nesting Project” by Dr. M.P.Mishra (Mangla Prasad Mishra) of Ranchi, then an expert on environment under the registered but small  N.G.O. named Prithvi foundation, based at Ranchi. Dr. Mangla Prasad Mishra (the author) had worked hard to research on nesting plans and designs of nests of different bird -species and nests of different styles and shapes were hanged in the local CCL and CMPDI campuses for attracting birds of different species. The project was a grand success and different media on local level and PTI on National level had flashed the news story in 1995. A number of news papers on local and national level had printed the story with deep interest though the matter remained uncovered by the environment friendly news paper of India – The Hindu. Dr. M.P.Mishra was then the president of the People for Animals, the Delhi based NGO for the protection of animals. Currently, Dr. Mishra is a nominee for the committee for prevention of cruelty to animals under the Ministry of Environment and Forest, though he has not received even an ID card to that effect in spite of his contribution to the cause of environment and animals.

Happy with the efforts of Dr. Mishra, Smt. Maneka Gandhi, the Chair Person of PFA had tried to popularize the work by Dr. Mishra but except the PTI coverage and few scenes on Television, Dr. Mishra’s research fell into deaf years and no one either from the government side or from the other side came to encourage him. The project could run on local level with the financial help to Prithvi foundation  from the local Jain community who love living beings, and yes CCL and CMPDI too could help a little to the organisation. But the novel project remained neglected by all and even by those who were really concerned with the environment and conservation.

A researcher in the field of Phytopathology and environment and an author of more than twenty books on Environmental Issues, Dr. Mishra is going on working in the fields of animal welfare and environment for his self content . An innovation thus  remained suppressed for  fifteen long years, but thank God some noble people finally got attracted after 15 long years by the work of Mr. Md. E. Dilawar at least, whose interview was printed by India’s Environment Friendly News Paper in March 2010 and, though late the Time finally came down to honor a hero, though not first in the field.

The above story reveals that there is late with the Gods but there is no injustice at all. Some say that -justice late is justice denied. But here as I am referring to God and not to any human being- I can say that the justice has not been denied, though it took quite 15 long years, or numerous birds might had been saved and protected so far. The conservation had started long ago when the Silent Spring was published. But the award giving organisations and our ministries wake up rather late, and this is the trend why new and original researches have been facing severe negligence in this country.

 The inference also comes out that some type of encouragement, big banners, and high connections yield too much. Lack of circulation also has been a big hurdle as happened with Charles Darwin and Mendel. But Dr. Mishra’s research that is the Bird Nesting Project did not remain uncovered, may be that the so called scholars and award giving agencies have some of their own preferences. See for yourself the visual and the scanned copies of the news reports seen and published in 1995. Dr. M.P.Mishra is a  teacher by profession and being associated with a small organisation at that time, he and his important work might have been subjects of overlooking or under some type of under estimation.See for yourself the news papers’ clippings published in 1995, 15 years ago and photo of Dr. M.P. Mishra working on the nest design for some bird other than sparrow in the current image. One thing contrary to Md. E. Dilawar’s statement published in the interview (The Hindu, March 14) is that - birds never accept artificial nests as these are hanged. Rather, they don’t believe it for some days. Later, they bring their own nesting materials as per their preferences which vary from species to species and design their own nest inside the wooden nest used by a human being. Yes, see down the image and news paper clippings and try to compare Dr. M.P.Mishra's photograph  of that time with the current one given here.

Click to enlarge the image

Please Click to enlarge the images



Allelopathy: a philosophy behind researches towards sustainable agriculture

>> Saturday, March 27, 2010

In human societies one man of certain class or level tries to check or inhibit the growth and development of the other man of the same or different class or level. Not all humans tend to do so, but some do. In 2001, two students of High School namely Overcast and Cox showed through their studies that when Kochia plant (Kochia scoparia) preceded spring wheat (Triticum aestivum), it inhibited growth of the spring wheat in terms of delayed emergence of seedlings, decreased rate of growth, decreased final height and reduced average dry weight of the spring wheat. The study was done in North Montana (U.S.). Overcast and Cox presented their study in the International Science and Engineering Fair (ISEF) in 2001 and were awarded a First Place team prize in the international event. Later, through a standard and larger study it was shown that Kochia seemed to produce allelopathy on some other crops too in the same area. Now, what is allelopathy? 

Image :1 Kochia

The biological phenomenon by virtue of which some organisms like algae, bacteria, coral and fungi influence the growth and development of other organisms by the help of some biochemicals they produce; is called as allelopathy. The biochemicals produced in this process are called allelochemicals.

In other words, the production of specific biomolecules by one plant to induce suffering in or to offer benefit to another plant is termed as allelopathy. In this case, the biomolecules produced for causing harm or benefit to a neibouring plant, are allelopathic chemicals. The effects of allelochemicals may either be beneficial or detrimental to the neighbouring organism. The allelochemicals are called Secondary Metabolites as they are not required for primary life processes. Based on beneficial or harmful effects, allelopathy has been classified as positive and negative.

Benefits from allelopathy
Some plants acquire more of the available resources like nutrients, water and sunlight from the surrounding environment without producing any chemical and initiating any chemical reaction. This process is called as competition. Since this process does not require any chemical action, this has not been put in the category of negative allelopathy. However, competition and negative allelopathy can act together and enhance the survival rate of a species.

Image :2 Garlic Mustard(Alliaria peteolata, Mustard family)

It has been reported that allelopathic interactions play a crucial role in natural as well as man made ecosystems. Allelopathy is an important factor which contributes in determining distribution of species and their abundance within communities. Allelopathy is also helpful in the success of many invasive species. The spotted knapweed (Centaurea maculosa, family Asteraceae), Nut sedge (Cyperus sp. Family Cyperaceae), and Garlic mustard (Alliaria peteolata, Mustard family) are three specific examples.

Image :3 Nut sedge (Cyperus sp. Family Cyperaceae)

Some specific examples of allelopathic weeds
C. maculosa is reported to contain Catechin and stereoisomer of Catechin which act as herbicide to inhibit competition by a wide range of other plant species. This compound is phytotoxic which is reported to inhibit seed germination and growth by making phosphorus more available in certain soils. As a result acidification of cytoplasm of the cells of competing plants starts which kills the cells. However some plants like Gallardia grandiflora and Lupinus sericeus are reported to be resistant to Catechin-induced toxicity.

Friedman and Horowitz(1971), Horowitz and Friedman (1971) and Singh et al.(1970) found that purple nutsedge tubers produced phytotoxins inhibiting the growth of other plants in the neighbouring areas. Chwen- Ming Yang, 1991, through an important study on “Allelopathic Potential of Purple Nutsedge (Cyperus rotundus L.), and Barnyardgrass (Echinochloa crus-galliBeauv.) on Corn. I. Inhibition of weed extracts on germination” showed that Aqueous extracts from field-grown mature plants of purple nutsedge and barnyardgrass were employed to study their allelopathic potential on corn (Zea mays L. cv. Tainung 1) germination. Such effects in response to temperature gradient were also investigated. The results confirmed the existence of allelopathic potential on corn germination in both extracts at concentration of 1 g ground powder/10 ml double distilled water. It has been reported that Water extracts of shoot of common lambs quarters (Chenopodium album), yellow nutsedge (Cyperus esculentus) and sunflower (Helianthus annuus) at 1% level significantly reduced soybean seed germination.

As for Garlic Mustard following report can be quoted as a ready reference -
The study report published in 2006 concluded that Garlic Mustard produces allelochemicals that harm mycorrhizal fungi that many North American plants, including native forest trees, require for optimum growth. Additionally, because White-tailed Deer rarely feed on Garlic Mustard, large deer populations may help to increase its population densities by consuming competing native plants. Trampling by browsing deer encourages additional seed growth by disturbing the soil. A complication to the eradication of Garlic Mustard from an area is the longevity of viable seeds in the ground. Seeds contained in the soil can germinate up to five years after being produced. Garlic mustard has been classified as Magnoliopsida.

Garlic mustard produces a variety of secondary compounds, including the flavonoid isovitexin 6″-O-β-d-glucopyranoside as a feeding deterrent to Pieris napi oleracea defense proteins, glycosides, and glucosinolates that reduce its palatability to herbivores.Research published in 2007 shows that, in Northeast Forests, garlic mustard rosettes increased the rate of native leaf litter decomposition, increasing nutrient availability and possibly creating conditions favorable to garlic mustard's own spread. 

Garlic mustard poses a severe threat to native plants and animals in forest communities in much of the eastern and midwestern U.S. Many native wild flowers that complete their life cycles in the springtime (e.g., spring beauty, wild ginger, bloodroot, Dutchman's breeches, hepatica, toothwort, and trilliums) occur in the same habitat as garlic mustard. Once introduced to an area, garlic mustard out-competes native plants by aggressively monopolizing light, moisture, nutrients, soil and space. Wildlife species that depend on these early plants for their foliage, pollen, nectar, fruits, seeds and roots, are deprived of these essential food sources when garlic mustard replaces them. Humans are also deprived of the vibrant display of beautiful spring wildflowers. Garlic mustard also poses a threat to one of our rare native insects, the West Virginia white butterfly (Pieris virginiensis). Several species of spring wildflowers known as "toothwort" (Dentaria), also in the mustard family, are the primary food source for the caterpillar stage of this butterfly. Invasions of garlic mustard are causing local extirpations of the toothwort, and chemicals in garlic mustard appear to be toxic to the eggs of the butterfly, as evidenced by their failure to hatch when laid on garlic mustard plants. 

The History of allelopathy
The negative effects of one plant on the other plant was reported for the first time far back around 300BC by Theophrastus who studied inhibitory effects of pigweed on alfalfa. Yang and Tang in China describe 267 plants having pesticidal abilities and allelopathic effects. De Candolle, the eminent Swiss Botanist reported in 1832 about soil sickness caused by plant exudates. 

The term allelopathy is a synthesis of two Greek words – allele and pathy, meaning mutual harm or suffering. This word was first used in 1937 by Professor Hans Molishch of Austria in his book entitled “Der einfluss einer pflanze anf die andere – Allelopathic L.” (Qillis, Rick J.2007). In this book the term allelopathy has been used by the author to describe biochemical interactions through which growth of one plant is inhibited by a neighbouring plant (Roger et al. 2006).

Whittaker and Fenny studied biochemical interactions among plants in 1971. In their research report which was published in the journal Science they have defined allelochemicals as all chemical interactions among organisms. In 1984, Elroy Leon Rice included all direct positive and negative effects of a plant on another plant or on microorganisms by releasing biochemicals into the natural environment. Thus he elaborated the definition of allelopathy given by Whittaker and Fenny in 1971. After Elroy Leon Rice the term allelopathy remained in use to describe broader chemical interactions between organisms.

The International Homoeopathy Society in 1996 described the term allelopathy as mentioned below –

“Any process involving secondary metabolites produced by plants, algae, bacteria and fungi that influence the growth and development of agriculture and biological systems.”
Later, Zoologists too started using the term to describe chemical interactions that occur among invertebrates like corals and sponges.

Ecologists the world over argue that the effect of competition can not be distinguished from allelopathy. They are of the opinion that competition is a negative effect which is produced when two or more organisms attempt to use the same resource directly. However, some researchers in 1970s reported that competition was different from allelopathy and produced sufficient facts in favour of their reports.

Role of allelopathy in agriculture
Researches done in the fields of ecology and agriculture show sufficient amounts of study on the effect of allelopathy in agriculture. These researches have been focussed on the effects of weeds on crops, effects of crops on weeds, and effects of crops on crops. Some of the modern researches done in the field are helpful in determining the possibility of using allelochemicals as growth regulators and natural herbicides so as to promote sustainable agriculture. Now, a number of allelopathic chemicals are available in markets. For example, Leptospermone is a thermo chemical in Lemon bottle brush (Callistemon citrinus). On commercial basis, this chemical no longer remained effective as a herbicide. However, its analog mesotrione was proved effective on experimentation. Mesotrione is now sold in markets and is prescribed for the control of broad leaved weeds in corn. It has also been proved effective in controlling crab grass in laens. In 1993, Sheeja studied the allelopathic interaction of Chromolaena odoratum and Lantana camara on some crops.

Application of allelopathy on desert shrubs
In 1964, a study of Salvia leucophylla deserved the place of cover story of the reputed journal Science. The research showed that bare zones around these shrubs were caused by volatile inter penetrates emitted by the shrubs. However, this story was criticized for being based on artificial laboratory experiments and unwarranted extrapolations to natural ecosystems. In 1970, a research published in Science showed that when the shrub was caged, grass grew in the bare zone. It was inferred that rodents and birds could not reach to the bare zone, grass grew un damaged (Halsey, 2004).


1. Bais HP, Walker TS, Stermitz FR, Hufbauer RA, Vivanco JM (April 2002).”Enantiomeric dependent phytotoxic and anti-microbial activity of Catechin. Arhizosecreted racemic mixture from spotted Knapweed”  Plant Physiol. 128 (4): 1173–9.  
2. Cyperus rotundus is one of the most invasive weedsknown, having spread out to a worldwide distribution in tropical and temperate regions. It has been called "the world's worst weed" as it is known as a weed in over 90 countries, and infests over 50 crops worldwide.
3. DROST, D.C. & DOLL, J.D., 1980. The allelopathic effect of yellow nutsedge (Cyperus esculentus) on corn (Zea mays) and soybean (Glycine max). Weed Science 28, 229-233.
4. Friedman,T. and Horowitz, M.1971. Biologically active substances in subterranean parts of purple nutsedge. Weed Sci.19:398-401.
5. Horowitz,M and Friedman,T.1971. Biological activity of subterranean residues of Cynodon dactylon L, Sorghum halepense L, and Cyperous rotundus L. Weed Res. 11; 88-93.
6. Singh,N.,Kulshreshtha, V.K.,Gupta,M.B. and Bhargawa, K.P. 1970. Apharmacological study of Cyperous rotundus. Indian J. Med.Res. 58: 103-109.
7. RICE, E.L., 1995. Allelopathy in forestry. In: E.L. Rice (ed.). Biological control of weeds and plant diseases: Advances in applied allelopathy. University of Oklahoma Press. Norman. 317-378.
8. TAMES, R.S., GETSO, M.D.V. & VIEITEZ, E., 1973. Growth substances isolated from tubers of Cyperus esculentus var aureus.Physiology of Plants 28, 195-200.



Decline in productivity of forest and agriculture

>> Friday, March 26, 2010

The increasing human population has put tremendous pressure on land for housing, agriculture, farming, pasture development, grazing by cattle and the production of various types of consumer goods through industrialization. For this land has to be acquired by claiming wetlands, mangroves and by large scale deforestation. In Indonesia; about 68000 sq km of land have been allocated for new plantations for the production of palm oil. Here are some more examples of decline in forest productivity due to different reasons.

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1. The total forest area in the world has been estimated to be around 3,869 million hectares. Out of this area about 95% is covered with natural forest and 5% is covered with regenerated forest. The natural forests are being lost or being converted to other uses of land at an alarming rates. For example, about 16.1 million hectares of natural forests were lost during 1990 – 2000.The annual forest loss at the Pan-tropical level has been estimated to be 9.2 million hectares.

2. According to the Food and Agricultural Organisation, the global loss of forests during the period1990 – 2000 has been around 9.4 million hectares per year.

3. The destruction of forests and grasslands is causing extinction of more than 12% of bird species, 25% of mammal species and about 33% of amphibian species.

4. In spite of increasing awareness about deforestation on global scale during recent years, the total area under forests is declining continuously.
5. About 850 million hectares of forest land is degraded in Asia and Pacific accounting for 24% of the region’s land. It was during 1981 – 1990 that deforestation in Asia and Pacific regions increased from 3.9 million hectares per year against 3.9 million hectares per year during 1981 – 1990.On the global level, the annual forest loss runs at about 12 million hectares per year, mostly in developing countries.

6. The period between 1976–,has been the period of Plantation Forestry. During this period, dense forest cover was destroyed from 46 to 36 million hectares which reduced the livelihood options for forest dependent poor people especially tribal people.

The land denuded of forests, is taken away with the rain water to cause the Siltation of rivers which finally leads to frequent floods. Floods claim large number of lives of humans and cattle every year. Great properties are ruined by devastating floods and great amounts of money are spent on rescue and rehabilitation of people. Thus, the decline in the forest productivity causes great losses to economy.

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Forests are sources of various economically valued products. They provide important services to environment and human beings. Some most important examples are being mentioned here.     
 1. Forests provide timber and significant revenue is derived from harvesting and processing of timber by private and government sectors.
2. Forests provide over 13 million tonnes of fuel wood per year in India alone.
3. Forests provide medicines, gums, resins, alkaloids leaves worth crores of rupees every year.
4. Forests provide other commodities of great economic value like lakh and silk.
5. Forests provide shelter to numerous species of birds, mammals, reptiles, amphibians, molluscs, insects and rodents etc.
6. Forests provide job opportunities for about 50 million people in the developing countries.
7. According to recent calculations natural forests store about 430 billion metric tonnes of carbon, which is more than the carbon released by the burning of fossil fuels over the next 70 years or so.
8. Reports suggest that one hectare of mangrove forest offers more than US $ 1,000 to a country.

Causes of decline in Forest Productivity
The world average of per person forest cover is estimated to be one hectare where as in India; it is just 0.10 hectare or so. Forests of India are being destroyed at the rate of 12.5 million hectares per year. If this trend continues, a day may come when we may have to face acute environmental crises in all fronts. We have already studied about all possible reasons of the depletion of the forest cover, and that need not be repeated here in detail. How ever to recall , some important reason behind the depletion of the forest cover are – the explosion of human population, overgrazing by cattle like sheep and goats, mining activities and heavy industrialisation , deforestation along hill slopes and the construction of roads along hillsides. Since forests contribute a lot to the national and local economy up to remarkable extent, loss of forest economy is a serious loss to the national economy.

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Efforts to Recover the Loss of Forest Productivity and to Improve the Economy
There is an increasing awareness regarding the impact of the loss of the Forest Productivity on economy across the world. People are now relying on plantation for the production of industrial wood. Nearly half of the plantation in the world is not more than 15 years old. Asia has become the world leader in terms of plantation as more than 62% of all the forest plantation done by the year  2000 across the globe, has been done in this region alone. Some very important signs of human efforts for raising forest productivity are –

1. The Private Sector Investment in plantation in developing countries has gone up during recent years.
2. The foreign investment in plantation sector has increased considerably.
3. Communities and small landowners are producing trees for selling to private companies and generating income though it is doing a very little good to environment.
4. The timber harvesting has been banned by many countries in order to conserve their forest resources or to check the economic losses due to natural calamities like land slides or floods.
5. Some countries have put restrictions on the export of wood so as to address the problems of national environment and markets.
6. The World Trade Organisation (WTO) Committee on trade and environment and the Intergovernmental Forum on Forests are considering issues pertaining forest trade.

Agricultural Productivity
The rate of production of agricultural goods in a unit period of time is called as Agricultural Productivity.
In more simple terms, the production of flowers, fruits, vegetables, legumes, nuts, millets, tubers, corms, roots, leaves, herbs and other agricultural products in unit period of time(say one season or one year), is called as Agricultural Productivity.

Food is the most important agricultural product. But many other products like natural fibres, flowers, forage (like alfalfa, clover grasses etc.), and many other products are also obtained from agriculture. About 85 major crops are grown in the world. Some important crops are: cereal grains,(e.g. barley, maize, oat etc. millets, rye, sorghum and wheat), roots(sweet potato, cassava etc.), pulses, oil bearing crops, nuts, sugar bearing crops, cocoa beans, coffee, tea etc. Cotton, flex, hemp, jute, sisal etc. produce plant fibres. Some farms provide raw materials for industry: like fibre, natural rubber, castor oil, linseed oil, tobacco etc. These agricultural products support greater part of the world economy. But human activities leading to soil degradation, pollution, encroachment on agricultural lands, wetlands, mangroves etc. have posed seriously bad impacts on agricultural production and economics of the world.

Today, a variety of crops are grown through mixed farming methods. These crops are produced for commercial purposes. Farmers in Europe and Mid- Western United States do mixed farming for great productivity. This type of farming is less risky than specialized farming. Thus market price for a particular product may decline sharply. On a mixed farm, losses from one product may often be covered by profits from the other product.

Decline in Agricultural Productivity
Two –third of the world’s agricultural land has been degraded. About 1.2 billion poorest people of the world inhabit those lands. They work hard. Still the agricultural productivity is very low in those areas.The declining land productivity in many cases has forced people to encroach on forests, grasslands and wetlands. These conditions cause further degradation of environment and decline in agricultural productivity.

Climatic variations and human activities are causing droughts, land degradation and desertification. As per reports of United Nations Convention to Combat Desertification (UNCCD) -2000a, about 3600 million hectare or 70% of the world’s dry land are degraded. Africa, Asia and small island states are facing serious economic losses due to land degradation caused by declining productivity of land due to climate change.

Agricultural productivity declines considerably due to floods and the climatic change. The degradation of land, Siltation of rivers, pollution of soil from acid rains and industrial wastes are some of the issues that are associated with urbanisation and industrialization that are strong causes of land degradation and decline in agricultural productivity. As per estimates of Food and Agricultural Organisation (FAO) - 1996, about 1.96 million hectare of land has been degraded by industry and urbanisation. Urbanisation has also caused damages to urban agricultural agriculture on public and private lands. For example about 30% of the Russian Federation’s food is produced on 3 per cent of land in sub urban areas. The United States lost 400 000 hectare of farm land and China has lost up to 5 million hectares of farm land due to urbanisation. All these conditions have put tremendous impact on agriculture and decline in economy.

Most of the biodiversity loss has occurred during 20th century. According to FAO’s reports out of traditionally cultivated 7000 species for food only 120 are being cultivated today. All these declines in agricultural productivity reflect human activities pertaining to carelessness and exploitation.

Causes of Decline in Agricultural Productivity
 Following are the causes of the decline in Agricultural Productivity –
1. With the explosion in human population the agricultural land has gradually been converted into residential and industrial areas.
2. The need of production of more and more food forced people to go for commercial and extensive agriculture. These practices caused serious depletion of nutrients causing loss in the agricultural productivity.
3. The agricultural production was to be boosted up by the application of synthetic chemical fertilizers and crops were protected from pests and diseases by the applications of pesticides and fungicides. All these synthetic chemicals caused permanent losses in the further productivity of agriculture by causing degradation of lands.
4. Vast areas of productive land are destroyed by heavy mining and quarrying.
5.Frequent floods due to Siltation of rivers caused by soil erosion often leads to damage of the top soil at certain places causing serious soil degradation leading further to serious losses of agricultural productivity.
6. Irratic rainfall induced by human activities causes frequent drought conditions that further leads to causing crop failures and damages to the agricultural productivity.
7. The current practice of planting commercial varieties of trees on agricultural land instead of growing food crops is leading to serious losses to agricultural productivity.

Effects of Decline in Agricultural Productivity

  1. The decline in Agricultural Productivity is causing hunger in major parts of the world. The World Food Summit- 1998 set the goal of reducing the number of hungry people up to half. In spite of great improvements in the food production about half million people are still starving across the world. Thus, it has become evident that the Agricultural Productivity has become a driving force for economic and social developments. According to the International Atomic Agency- ‘When agriculture fails sources of income are lost. Social ties are disrupted and as a result, societies become more mobile.’

2. The decline in the productivity of the land under poor farmers created regional disparities. The Green Revolution was launched to enhance food production but only the rich farmers could derive benefits from it. The poor could not afford heavy prices of synthetic fertilizers and pesticides. Thus they remained hungry and economically backward in comparison to the rich. On the other hand, application of synthetic fertilizers and poisonous pesticides degraded the productivity of soil seriously. Thus the land even under the rich farmers no longer remained productive. These conditions are causing seriously bad impacts on the agricultural production during current times leading to a setback to the national economy. 

3. The agricultural growth created a gap between the rich and the poor states in the post green revolution period after 1980 – 1981.

4. The agriculture growth slowed by 2 per cent a year in the 9th Five Year Plan and the overall income growth was only 5.5 per cent where as the target was 8 per cent.

5. The decline in agricultural productivity is causing distress among farmers.

6. Poor maintenance of irrigation system causes loss of water through wastage and seepage. The scarcity of water affects crop production adversely.

7. Uncontrolled exploitation of ground water has caused serious depletion of water table in many parts of the country. It is leading to a water crisis and the failure of crops. Even after the exploitation of all the irrigation potential, up to 60% of India’s cultivable area is assessed to depend on dry land farming.  

  8. The decline in agricultural productivity has no longer left the agriculture profitable activity far general farmers. Hence, large scale migration of people from rural areas towards cities is increasing day by day. It is further causing urban congestions, expansion of slums and encroachments on government lands.

9. Declining agricultural productivity compounded with natural calamities which is aggravated by human factors is creating acute shortage of food. Many countries have to take loans from the International Monetary Fund (IMF) and the World Bank to import food and to feed its people.

All the factors mentioned above, heavily contribute to hunger and poverty together with causing bad effect on local, regional and national economies. 



Ocean Resources: Conservation and Management

>> Thursday, March 25, 2010

Seas and oceans provide various types of resources to human beings and habitats to numerous species of plants and animals. They play very important roles in the economy of a nation and its people. Still, the marine and coastal ecosystems are under severe stress due to human activities. Hence the conservation of these resources is very important, today.Our marine and coastal ecosystems are under heavy stress due to human activities. 

 Major stresses on marine ecosystems are listed below-
1. Pollution of marine water due to disposal of municipal, industrial, chemical and toxic wastes in the sea water.
2. Dumping of various biodegradable and non- biodegradable wastes including plastics and torn fishing nets etc. into sea water.
3. Over exploitation of living marine resources.
4. Heavy sedimentation of sea water.
5. Global climatic and atmospheric changes induced by human activities leading to atmospheric pollution.
6. Introduction of exotic species for example introduction of Jelly fish in the black sea.
7. Oil spills on water surface from ships and natural sources.

Stresses on coastal ecosystems are listed below-
1. Increasing pressure on terrestrial and marine natural resources cause coastal degradation.
2. Dumping of wastes in coastal areas intoxicate the coastal and estuarine waters.
3. Population growth, increasing urbanisation, industrialization and tourism in coastal areas damage coastal ecosystems.
4. Pollution of coastal water by industrial wastes is damaging coastal and estuarine ecosystems. Deaths of sea birds due to intoxication of sea-water by pesticides (DDT in particular) and outbreak of Mina Mata disease in Japan from mercury contaminated seafood are two examples of serious pollutions of coastal ecosystems.
5. Exploitation of living resources from coastal areas is causing excessive pressures on coastal ecosystems.
6. Contamination of sea water with sewage is causing nutrient enrichment of coastal ecosystems. It is further leading to a serious condition of eutrophication. The sewage discharge into sea water has increased dramatically in the past three decades. Several enclosed or semi-enclosed seas like the Black Sea are experiencing serious problem of eutrophication.
7. The contamination of coastal water by sewage borne pathogens is causing serious public health problems.
8. Port dredging, land filling, coastal solid waste dumps, coastal constructions, beech and reef- mining, damage from tourism and recreation are causing serious impacts on these ecosystems.
9. Destruction of mangrove vegetation has put severe stresses on these ecosystems.

Conservation and Management of Marine and Coastal Ecosystems 
According to a report of the UNEP( United Nations Environmental Programme), the degradation of marine and coastal ecosystems has intensified since last 30 years. The progress in the protection of these ecosystems has so far remained very slow. Fortunately, there is an emerging concern in some parts of the globe that the loss of living marine resources is as dangerous to the health of marine and coastal ecosystems as marine pollution. Some of the major threats to these ecosystems that have been identified are- pollutions, over- exploitation of marine living resources and loss of coastal habitats.

Major strategies of conservation and management of marine and coastal ecosystems are described below -
 India has a coastline of over 7,500 km .It has about 2 million sq km area within the Exclusive Economic Zone (EEZ). It has been authorised to explore about 150,000 sq km of marine area in the Indian Ocean by Seabed Authority which offers immense scope for exploration and study of ocean resources.

The Government of India created the Department of Ocean Development (DOD) in July 1981. An Ocean Policy Statement was brought out in 1982 by this department. Some of the features of this policy are- Exploratory survey; Assessment and sustainable utilization of ocean resources; Technical advances geared to the utilisation and preservation of the marine and coastal ecosystems; Integrated Coastal and Marine area Development; and Coastal Community Development.

The Government of India has created following systems for the conservation and management of marine and coastal ecosystems-
(i) Coastal Area Monitoring and Prediction System (OMAPS)-1990.
(ii) Two Coastal Research Vessels (under National Institute of Ocean Technology) namely - Sagar Purvi and Sagar Paschimi. These vessels are meant for the monitoring of marine and coastal pollutions for Integrated Coastal and Marine area Management.

The Integrated Coastal and Marine Area Management Programme (ICMAM) is a project under implementation since 1997. This project has two major components- (a) Capacity building, and (b) Development of infra structure for research and development.The capacity building component of ICMAM incorporates-
(a)Development of information system for critical habitats of India such as Gulf of Khambat, Karwar Island, Gulf of Kutch, Cochin Islands, Sunder bans, Malwan, Kadmat Island, Gulf of Mannar,Pichavaran, Caring and Gahirmatha.
(b) Development of guidelines for Environmental Impact Assessment.
(c) Development of Model Integrated Coastal and Marine Management Plans for Chennai, Goa, and Gulf of Kutch.

On global level, India ratified the UN Convention on Law of the Sea (UNCLOS) in June 1995.The Department of Ocean Development is a nodal agency for the implementation of the provisions of UNCLOS in India. Soon after the enforcement of UNCLOS, some institutions like the International Seabed Authority (ISBA) and Commission on the Limit of Continental shelf (CLCS) were formed.

Key Words : conservation, stress, marine resources, coastal resources,dumping, sedimentation, exotic species, enclosed and semi enclosed seas, black sea, DOD, UNCLOS, CLCS


What is the Theory of Demographic Transition?

>> Wednesday, March 24, 2010

The term ‘Demographic’ relates to the scientific study of populations and the term ‘Transition’ means- ‘the process and periods of changing from one state or condition to the other state or condition’. Thus, the Demographic Transition means- ‘The scientific study of the process or period of changes in a population from one state or condition to another state or condition.

An eminent demographer Frank Notestien outlined a theory which emerged out of his observations pertaining to the effect of economic and social development on the growth of population. His theory of demographic transition has provided the conceptual basis for demographic researches.

According to the theory of demographic transition, all the human societies may pass through any one of the three phases at a particular point of time. These phases are – First phase or Lag Phase, Second phase or  rapid growth phase, Third phase or Stabilization phase and the Fourth phase. The change over in population dynamics from one phase to the other is called as demographic transition.

Frank Wallace Notestein (August 16, 1902 - February 19, 1983) was an American demographer who contributed significantly to the development of the science. He was the founding director of the office of Population Research at Princeton University, and later president of the Population Council. He was also the first director of the Population Division of the united Nations, 1946-1948.According to Daniel Taylor an independent researcher, activist, and webmaster of – He “was one of the most influential population control activists and demographers of the 20th century. His work led to the establishment of demography as an academic discipline. He worked as the first director of the population division of the United Nations, was instrumental in the founding of John D. Rockefeller's Population Council in 1952, and was a director of population research at Princeton University.

In a paper written by Notestien in 1969 titled "The Problem of Population Control," he outlines a strategy of quickening the pace of depopulation. Notestien admits that economic modernization would "...bring the birth-rate down automatically." However, he goes on to state that more drastic measures must be taken because in his opinion this method would not be fast enough. "coercion" and the "institution of a totalitarian regime" are Notestein's solutions.

"...The need for an early reduction of the birth-rate is acute. Birth-rates in the past have fallen most rapidly in the context of modernization and social-economic change. But there is nothing in the European experience to suggest that we must rely solely on gradual and automatic changes in society. One often meets the glib generalization, particularly in the underdeveloped countries, that it is only necessary to concentrate on social and economic modernization since it is well known that we can rely on these processes to bring the birth-rate down automatically. The argument neglects the time-span required for such an adjustment... Even if we could be assured of rapid social and economic development the lag in transition between reduction of death rates and the reduction of birth rates poses enormous problems of population growth."

Notestien continues-
"...even if successful, voluntary family planning programs cannot be expected to resolve the world population dilemma. Even in the more developed countries, and notably in the United States, surveys show couples desiring more children than are necessary for replacement... Thus we cannot rely on the self-interested choices of individual couples to met society's needs. The only acceptable goal is zero rate of growth because any rate of growth continued long enough leads to astronomical figures. Given existing preferences in family size, governments must go beyond voluntary family planning. To achieve zero rates of population growth governments will have to do more than cajole; they will have to coerce."

"The logical target for legal and institutional pressures is the family: pressures to postpone marriages; economic pressures and inducements for married women to work outside the home; provision of free abortions for all women requesting them; downgrading of familial roles in comparison with extra familial roles; and restriction of housing and consumer goods... Such institutional changes supply motivation for family limitation and the provision of free abortions affords a means. The implications of such major institutional changes go far beyond population control. The family is the basic social unit of society and its major institution for the socialization of the children... to impose more drastic changes on a large scale implies many risks, not least to the regime that undertakes them. The price for this type of population control may well be the institution of a totalitarian regime."

According to this theory, high birth rates and high death rates to low birth-rates and low death rates are important parts of the economic development of a country from pre-industrial to an industrialized economy. This theory is usually described through demographic transition model (DTM) which describes population changes overtime.

The Demographic Transition Model involves four stages and these four stages are are summarised below-
(i).Birth rates and death rates are high in pre-industrial societies. Their population fluctuates rapidly according to natural events like drought, diseases etc. Thus relatively constant young population is produced.
(ii).The death rates drop rapidly in developing countries due to improvements in food supply, sanitation and healthcare facilities. It increases life spawn and reduces diseases. Countries in this stage experience heavy increase in population.
(iii).Birth rates fall due to contraception. This supports increase in wages, urbanisation, reduction in subsistence agriculture, an increase in the status and education of women and other social changes.
(iv).Both low birth rate and low death rates are observed in stage four. Low birth rates results in shrinking of population which is a threat to many industries that rely on population growth. Death rates may remain consistently low or increase slightly due to increases in lifestyles.Now that the birth rates have started declining, it appears that India has entered into the third stage of demographic transition since 1971.

Life -Tables
The statistics of mortality and life expectancy for different age groups of people in the population are represented by means of tables. These tables are called as Life- Tables. These are tables designed to evaluate how characteristics of population influence the overall growth rate of a population. Life Tables were originally developed by Insurance Companies to provide a means of determining how long any person of a particular age could be expected to live. Life Tables are also used by ecologists for plant, animal and microbial populations and for making projections about life expectancies. On the basis of life tables demographers and Ecologists plot Survivorship Curves. These curves represent number of individuals in a population that can be expected to survive to any specific age.

Uses of Life- Tables
Life tables are used for many different purposes like: (i) computation of average longevity of a population, (ii) representation of age-composition, (iii) indication of critical stages in the life cycle at which mortality is high, (iv)showing differences between species etc.

Key Words : demography, Frank Notestien,Lag Phase, rapid growth phase, stabilization phase, American demographer, demographic transition model,United Nations ,Ecologists plot Survivorship Curves,life- table. 


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