A Primer of Ecology

An article by Mohan Pai

(This is the last chapter from my book “The Western Ghats” published in 2005)

“There is nothing in nature to prove that it cares more for our human species than daffodils. We may one day vanish as quickly and as radically as thousands of other breeds before us. Mother nature has no mama’s darlings…when the balance of nature is threatened, it always finds a way to restore that balance, at whatever cost. If endangered by us, nature will strike back and show no more concern for Michaelangelo, Shakespeare or Mozart than for daffodils. We are dealing here with an overwhelming force, that of life itself and we know next to nothing about it. The only thing we know is — nature has no favourite among species.

Romain Grey  in ” Vanishing Species”



How to destroy a fragile ecosystem


10 Easy Steps

Ecosystems such as the Western Ghats which have global significance, are classified as HOT SPOTS. Globally, about 18 hot spots have been identified. These spots are extremely rich in species, have high endemism, and are under constant threat. Hotspot areas are particularly rich in floral wealth and endemism, not only in flowering plants but also in reptiles, amphibians, swallow-tailed butterflies, and some mammals. These
are extremely fragile biosystems and need to be nurtured and protected for the sake of the environmental well-being of the people. However, we are witnessing a mindless destruction of these systems.

The 10 EASY steps adopted for the destruction process are as follows:

1. Destroy as much as natural forest as possible by clear felling. Plant monoculture (teak, eucalyptus, acacia, etc.) in the name of afforestation.
2. Build dams for irrigation and power. In the process, destroy thousands and thousands hectares of natural forest. Allow the area to be submerged and displace the tribals and local populat ion. Promise resettlement – over the years keep promising – make trauma of displacement more painful. In the process, also kill a vast number of endemic species in the area, so that they are lost forever. Also decimate wild life of the area by submersion or fragmentation of their habitat. Blasting of rocks, the
rumble of machinery, the incursions by human help greatly in reducing the fauna in the Ghats.
3. Allow encroachment in the forest area and then legalise it through legislation.
4. Start large-scale mining operations within the forests. Apart from destroying the habitat complex of highly threatened flora and fauna, it will result in high degree of pollution of the rivers and land surrounding water course. The forests will be replaced with heaps of mined waste. It will also effectively kill and re duce the aquatic fauna. There will be a decline in agricultural productivity due to deposition of mine tailing.
5. Establish large-scale paper mills and plywood units by clearing large tracts of prime forest land and allow them a free hand with the forest timber.
6. Install an Atomic Power Plant right in the midst of the forest again by destroying an immense amount of prime forests. Ignore the hazards it entails for the area.7. Build Railways through the thick forest and cause as much damage as possible through clearing the prime forests and
8. Clear large tracts of natural forests for cash crops like coffee, cardamom, tea, spices, etc.
9. Protect poachers and smugglers – offer them political patronage so that they can kill with impunity thousands of tuskers for Ivory and other endangered animals for their skins; smuggle out millions of tonnes of valuable timber.
10. Pass on this knowledge to your children so that whatever green patches may be left could be effectively eliminated in the end.

What is ECOLOGY ?

All life on the earth is interrelated and interconnected in someway or the other. Living organisms are dependent upon their physical environment – the land, water, air.The study of the interrelationship between plants, animals, and the environment is called ECOLOGY.One of the fundamental aspects in ecology that helps us understand the interrelationship between plants and animals, animals and animals and plants, animals and human beings, is their requirement of food.Food chains & food-web.Green plants are the primary producers of food. They make simple carbohydrates during the process of photosynthesis, with the help of carbon dioxide and water by utilisation of the energy received from the Sun. When herbivore animals eat plants, they get energy through this food. When they are eaten by carnivore, the latter get the energy required for their life activities. For example: grass —> grass hopper —-> frog. This is a simple food chain. Now, if a frog is eaten by a snake, and the snake by an eagle, it becomes a complex food chain. Several such food chains exists in nature. An interconnected network of different food chain that occurs among inhabitants of a particular natural habitat is called food-web. The food-web is a delicate network of interrelationship between the species involved, representing a balanced and self-contained living system. Destruction of any one link in this food-web will have an adverse impact on the other or the entire system itself. For example if the carnivores like tigers and leopards are exterminated, the population of the deer will increase unchecked and this in turn would destroy the vegetation more rapidly, giving no time for plants to regenerate.

Interrelationships in nature take many forms – plants and vegetation provide home for animals; insects and birds pollinate flowers; animals help the dispersal of seeds of plants; parasites infest plants or animals. Some are beneficial associations between organisms (symbiosis) and others are not. There are also nature’s cleanup crew – the crow, the eagle, the hyena, and others who act as scavengers and bacteria aiding in decomposing the dead which play an important role in returning organic and inorganic components of dead animals and plants back to nature, to be used and reused by subsequent living organisms.

Nature provides a very complex, yet balanced, interrelationship between plants and animals. Together with the biogeochemical cycles such as water cycle, carbon cycle, nitrogen cycle, mineral cycle, etc., recycling essential elements between living organisms and the environment; all life on the earth is interconnected. It is necessary to understand these ecological relationships to appreciate the importance of conservation of animals and plants and the non-living resources that nature has provided on our planet earth.

Biosphere & Biomes

Life on the earth may have begun to evolve some 3,500 million years ago. Today there are over half-a-million variety of plants and a million different kind of animals.

All life is confined to a thin layer of the earth called BIOSPHERE. The Biosphere of the earth can be divided into a number of BIOMES or natural habitats with specific climatic and geographical characteristics that help sustain a variety of plants and animals adapted to survive in a particular region.A biome is made up of biological communities that interact with each other in a particular life zone. A tropical rainforest, for example, is a biome which is the home for a wide variety of plants and animals suitably adapted to live in the habitat that constitutes the forest. The higher canopy of tree branches sustain arboreal animals, such as monkeys, flying squirrels and birds; the dense forest floor sustains tigers, deer, snakes, insects, millipedes, etc.The rainforest is characterised by warm and moist climate with plenty of rainfall. Similarly oceans, lakes, grasslands, wetlands,coniferous forests, deciduous forests, deserts and coastal regions constitute different biomes or self contained environments with typical plants and animals suitable to survive in these habitats.Thus nature provides an extremely complex and intricate network of living things delicately balanced and adapted to inhabit the diverse climatic and geographical regions on our planet. This is our natural heritage; a heritage in which we ourselves are one of the many species of animals, depending upon the entire system for our sustenance and survival.

What is biodiversity ?

The term Biodiversity encompasses the variety of all life on the earth. It is identified as the variability among living organisms and the ecological complexes which they are part, including diversity within and between species and ecosystems. Biodiversity manifests at three levels:
a) Species diversity which refers to the numbers and kinds of living organisms.
b) Genetic diversity which refers to genetic variation within a population of species.
c) Ecosystem diversity which is the variety of habitats, biological communities and ecological processes that occur in the biosphere.Biological diversity affects us all. It has direct consumptive value in food, agriculture, medicine, industry. It also has aesthetic and recreational value. Biodiversity maintains ecological balance and continues evolutionary process. The indirect ecosystem services provided through biodiversity are photosynthesis, pollination, chemical cycling, nutrient cycling, soil maintenance, climate regulation, air, water system management, waste treatment and pest control.Biodiversity is not evenly distributed among the world’s more than 170 countries. A very small number of countries lying wholly or partly within the tropics, contain a high percentage of the world’s species. These countries are known as Megabiodiversity countries. Twelve countries have been identified as megabiodiversity countries: India, Brazil, Colombia, Ecuador, Peru, Mexico, Madagascar, Zaire, Australia, China, Indonesia and Malaysia. Together these countries contain as much as 60 to 70 per cent of the world’s species. India is one of the 12 megabiodiversity centres in the world.India is divided into 10 biogeographic regions:Trans-Himalayan, Himalayan, Indian desert, Semi-arid zone, Western Ghats, Deccan Peninsula, Gangetic Plains, North-East India, Islands and Coasts.


An ecosystem is a place where nature has created a unique mixture of air, water, soil and a variety of living organisms to interact and support each other. It is a living community of plants and animals of any area together with the non-living components of the environment such as soil air and water. The living and non-living interact with each other in such a manner that it results in the flow of energy between them. In a particular ecosystem the biotic community consists of the birds, reptiles, mammals, insects and other invertebrates, bacteria, plants and other living organisms.An ecosystem includes not only the species inhabiting an area but also features of the physical environment. Energy cannot be produced without the consumption of matter; the pyramid of life therefore has a wide base of vegetation, the smaller herbivores that feed on plants, and a much smaller number of carnivores. Eco-system ecologists are interested in the exchange of energy, gases, water and minerals amongst the biotic (living) and the abiotic (non-living) components of a particular system; therefore they tend to study confined areas that are easier to control or monitor. Small and relatively self-contained ecosystems are called microsystems because they represent miniature systems in which most of the ecological processes characteristic of larger ecosystems operate but on a smaller scale. A small pond is an example of a little ecosystem. On the other hand, the largest and the only really complete ecosystem is the biosphere. An ecosystem can exist in any place where there are varied forms of life. Even the park near your home or a village pond can be an ecosystem as there are different forms of life here and they coexist.
One of the most productive ecosystems is at the point where sea water meets freshwater.Conservationists have now realised that in order to save the natural world, ecosystems as a whole have to be saved. Unless the entire ecosystem is preserved, the individual species will not be able to survive for long.Human activities clearly demonstrate the interdependence of all ecosystems – acid rain that falls on forests is carried to pristine lakes far from the source of pollution.

Deforestation and the burning of fossil fuels change the composition of the atmosphere and perhaps contributes to the alteration of the earth’s climate. The most important lesson to be learned about life on earth is that most things on the earth are interdependent and interconnected – actions taken have a much larger impact than one can think of.

Genetic Biodiversity

All forms of life on earth, whether microbes, plants, or human beings, contain genes. Genetic diversity is the sum of genetic information contained in the genes of individual plants, animals and micro-organisms. Each species is the storehouse of an immense amount of genetic information in the form of traits, characteristics, etc. The number of genes ranges from about 1000 in bacteria to more than 400,000 in many flowering plants, each species consists of many organisms and virtually no two members of the same species are genetically identical.An important conservation consequence of this is that even if an endangered species is saved from extinction it has probably lost some of its internal diversity. Consequently when populations expand again, they become more genetically uniform than their ancestors. There are mathematical formulas to express a genetically effective population size that explain the genetic effects on populations that have gone through a bottleneck before expanding again such as the African Cheetah or the North American Bison.Subsequent inbreeding in small populations may result in A) reduced fertility and B) increased susceptibility to disease. Genetic differentiation within species occurs as a result of sexual reproduction, in which genetic differences between individuals are combined in their offspring to produce new combinations of genes or from mutations causing changes in the DNA.Genetic diversity is usually mentioned with reference to agriculture and maintaining food security. This is because genetic erosion of several crops has already occurred leading to the world’s dependence for food on just a few species. Currently, a mere 100 odd species account for 90% of the supply of food crops and three crops – rice, maize and wheat – account for 69% of the calories and 56% of the proteins that people derive from plants.


Species is a group of class of animals and plants having certain common and permanent characteristics that clearly distinguish it from other groups or species (Concise Oxford Dictionary). They are populations in which gene flow occur under natural conditions. By definition, members of one species do not breed with those of other species. Unfortunately, this definition does not work in species where hybridization, self fertilization, or parthenogenesis (reproduction of offspring without fertilization by sexual union) occurs. New species may be established in several ways. The most common method is a geographical speciation (formation of new biological species), the process by which the populations that are isolated diverge through evolution by being subjected to different environmental conditions. Biodiversity is most commonly used and measured by species diversity. There are two major reasons for this: Species are still the most identifiable collective unit of biological organization and the loss of species seems the most irreversible and final of all forms of diversity. Species diversity can be expressed in terms of richness, that is the number of species in an area – for example you can count the number of plant species in your garden which will give you the species richness in your garden. Thus, if you have one neem tree and one mango tree, the tree species in your garden will be two. Ecologists have come up with various diversity indices, which focus not only on the number of species present but also on the number of individuals of a particular species.Diversity indices are of more value to ecologists, since they give an idea of the composition of the communities existing in an area, and help identify species that dominate the community in terms of their abundance, biomass or cover. Species diversity is not uniform throughout the world, some areas are very species rich while others are species poor. Again while one area may have hundreds of plant species another may have an incredible insect diversity. A striking pattern is the increase in diversity from poles to the equator, thus while the tropical areas team with life, temperate areas which are closer to the poles have fewer kind of plants and animals, while the polar regions are stark and barren. Tropical forests are amazingly diverse, a single hectare may contain 40 to 100 different kinds of trees. In contrast in a coniferous or a deciduous forest only about 10 to 30 species can be found.Latitudinal variations are not the only emerging pattern. Diversity is also closely linked to altitude or elevation. The plains of India have a varied species of plants but as you go up, the decrease in the moisture contents in the atmosphere reduces the number of species. The desert area has the least number of species. There are certain species that are endemic to a region that is, they are found in only a particular area and are very special to that area. They have evolved to adapt to that area only and if their habitat is destroyed (e.g. by deforestation) they can easily become extinct. Some plants and shrubs are endemic to only a particular type of forest, such as some found in the evergreen forest will not be found in any other type of forest area. Take the Western Ghats as an example – animals endemic to this area include the Rusty Spotted cat, Nilgiri marten, the Lion-tailed macaque, and the Nilgiri langur.


The forest is a complex ecosystem consisting mainly of trees that have formed a buffer for the earth to protect life-forms. The trees which make up the main area of the forest create a specialenvironment which, in turn, affects the kinds of animals and plants that can exist in the forest.The FAO (Food and Agricultural Organization) has defined forest as land with crown cover (or equivalent stocking level) of more than 10% and area of more than 0.5 hectare. The trees should be able to reach a minimum height of 5 m at maturity in situ. In the tropical and subtropical region, forests are further subdivided into plantations and natural forests. Natural forests are forests composed of indigenous trees, not deliberately planted. Plantations are forest stands established by planting or/and seeding in the process of afforestation or reforestation. There are about 16 major types of forests in India from the tropical type to the dry type.Forests can develop wherever there is an average temperature greater then about 10 Centigrade in the warmest month and an annual rainfall in excess of about 200 mm annually. In any area having conditions above this range there exists an infinite variety of tree species grouped into a number of stable forest types that are determined by the specific conditions of the environment here. Forests can be broadly classified into many types some of which are the Taiga type (consisting of pines, spruce, etc.). The mixed temperate forests with both coniferous and deciduous trees, the temperate forests, the sub tropical forests, the tropical forests, and the equatorial rainforests.In India it is believed that organized exploitation of forest wealth began with an increase in hunting. Ashoka the Great is said to have set up the first sanctuary to protect the forest and all life in it. The Mughal rulers were avid hunters and spent a great deal of time in the forests.
It was during the British rule that the first practical move towards conservation in modern times took place. They established ‘reserved forest’ blocks with hunting by permit only. Though there were other motives behind their move, it at least served the purpose of classification of and control over the forests.
Soon after independence, rapid development and progress saw large forest tracts fragmented by roads, canals, and townships. There was an increase in the exploitation of forest wealth. It was only in 1970s that the importance of conservation of forests was realised and the preservation of India’s remaining forests and wildlife was given a front seat.

The Wetlands

Wetlands are areas lying along the banks of rivers and lakes and the coastal regions. They are life supporting systems providing fish, forest products, water, flood control, erosion buffering, a plant gene pool, wildlife, recreation and tourism areas. Though they are endowed with a rich biodiversity, yet of late they are being greatly exploited. Many Wetland species have become threatened and endangered because of their dependence on a particular type of wetland eco-system, which has become seriously degraded or destroyed. Such is the case with swampy grasslands and the flood plain wetlands of the Ganges and Brahmaputra river valleys. Large areas have been converted to agricultural land or there has been widespread over-grazing. Removal of sand, gravel and other material from the beds of rivers and lakes has not only caused destruction of wetlands but has led to sedimentation, which has affected other areas. The introduction of exotic plants has had an adverse effect on these areas. The water hyacinth, a native of South America, is now a major pest in many areas forming a vast floating shield over the surface of the water and clogging up rivers and canals. A number of factors have been responsible for the depletion of wetland areas, mainly the mangrove forests, along the coasts of India. Intensive aquacultural development, deforestation, pollution from tankers, domestic waste, agricultural runoff and industrial effluents are some of the factors. Most of the surviving mangroves are now confined to West Bengal and the islands in the Bay of Bengal.In 1981, Chilka Lake, India’s largest brackish water lagoon, was designated a Ramsar Wetland of International importance. But its fragile ecosystem has of late come under threat due to both anthropogenic and natural factors. It provides refuge to thousands of migratory birds and the balance in ecosystem has to be maintained to ensure safe habitat for the birds.

Exotic Species

As opposed to native species, which are indigenous and found naturally in an environment, animals and plant species introduced from other countries and which are not otherwise found locally are termed exotic. These introduced or exotic species can adversely affect the ecosystem.In India large variety of exotic animal and plant species, have been introduced from other parts of the world through the ages. Some exotic plants have turned into weeds, multiplying fast and causing harm to the ecosystem, e.g. Water hyacinth and lantana. Exotics are invariably introduced without their natural enemies that control and balance their spread in their native land, and hence grow and flourish without any hindrance and cause harm to the environment. Therefore, when planting saplings, remember to choose only those that form a part of the natural ecosystem of an area. In a stable ecosystem, all species – animals, plants and microbes – are in healthy coexistence. Any disturbance in one gives rise to imbalance in others and this is what happens when an exotic species is introduced.Introduced species can often negatively affect native species. While they are selected specifically for their adaptability and in the long run often out number native species and compete with them for the resources. This results in the expansion of the introduced species and the decline of native species. Plants from all over the world have been brought to India and grown here. Some have proved beneficial while others have not. Vegetables such as chillies and onion have been brought from South America and Persia (modern day Iran) respectively. Coffee, Cashew, eucalyptus and many more species have come from abroad. Some quick growing plant species were brought from Australia for afforestation programmes such as the acacia and eucalyptus. The demand for wood in different industries led to a growth of forest area under these species. These trees shed the leaves on the ground and do not allow other plants to grow nor do they decompose easily. During the rains there is heavy erosion and poor percolation in these areas. Thus the introduction of these species has caused more harm than good to the forests and the soil in general. Some weeds have not been intentionally introduced but have come accidentally as for instance the Mexican weed came along with American wheat that came as PL 480 aid from the USA in the 1960s when quarantine rules were not so strict. In fact all plants and seeds that come from another country should be quarantined to ensure that no other foreign material has come with it.

Source : Edugreen – Teri, New Delhi




 For some of my articles visit:


For some key chapters from my book “The Western Ghats”, please log on to:http://westernghats-paimohan.blogspot.com/

For detailed blog (6 Chapters) on Mahadayi/Mandovi River Valley, please log on to:http://mohan-pai.blogspot.com/

For the book ‘The Elderly’ please log on to:http://oldagecare-paimohan.blogspot.com/

You can also access my blogs on Sulekha:http://mohanpai.sulekha.com/blog/posts/pageno-1.htm



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