MOOCs by
Noida International University

Ecosystem, Bio Diversity and Natural resources

Course Description:

This course offers the basics topics of Ecosystem, Bio Diversity and Natural resources in detail to enable the learners understand the basics from the scratch.

What you’ll learn

After successful completion of this course students will be able

  1. To understand Renewable resources, Non-Renewable Resources
  2. To understand Problems associated with natural resources
  3. To understand Forest, Water and Natural Resources
  4. To understand Food Chain, Food webs and Ecological Cycle


Basics of Environmental studies




The word environment is derived from the French word “environ” meaning surroundings. Hence, everything surrounding us is called environment. Every organism is surrounded by materials and forces that constitute its environment. It is the environment from where every organism must derive its requirement. The environment creates favourable conditions for the existence and development of living organisms. The survival of any organism requires a steady supply of materials and removal of waste products.

The natural environment encompasses all living and non-living things. This environment encompasses the interaction of all living species, climate, weather, and natural resources that affect human survival and economic activity. Environmental studies are multi-disciplinary because it comprises various branches of studies like chemistry, physics, medical science, life science, agriculture and public health. It is the science of physical phenomena in the environment. Environmental studies deals with every issue that affects an organism. It is an applied science as its seeks practical answers to making human civilization sustainable on the earth’s finite resources.

The environment is constituted by the interacting systems of physical, biological and cultural elements inter-related in various ways, individually as well as collectively. These elements are-

  • Physical Elements

Space, landforms, water bodies, climate, soils, rocks and minerals. They determine the variable character of the human habitat, its opportunities as well as limitations

  • Biological Elements

Plants, animals, microorganisms and human beings constitute the biosphere.

  • Cultural Elements

Economic, social and political elements are essentially manmade features, which constitute the cultural milieu. 1.2. Scope and imp

Scope and importance

Environment Studies enlighten us about the importance of protection and conservation of our environment. At present, a great number of environment issues have grown in size and complexity day by day, threatening the survival of mankind on earth. 1 We live in landscapes that have been heavily modified by human beings, in villages, towns or cities. But even those of us who live in cities get our food supply from surrounding villages and these in turn are dependent on natural landscapes such as forests, grasslands, rivers, seashores, for resources such as water for agriculture, fuel wood, fodder, and fish. Thus, our daily lives are linked with our surroundings and inevitably affects them. We use water to drink and for other day-to-day activities. We breathe air, we use resources from which food is made and we depend on the community of living plants and animals which form a web of life, of which we are also a part. Everything around us forms our environment and our lives depend on sustaining its vital systems.

The industrial development and intensive agriculture that provides the goods for our increasingly consumer oriented society uses up large amounts of natural resources such as water, minerals, petroleum products, wood, etc. Non renewable resources, such as minerals and oil are those which will be exhausted in the future if we continue to extract these without a thought for subsequent generations. Renewable resources, such as timber and water, are those which can be used but can be regenerated by natural processes such as re growth or rainfall. However, these too will be depleted if we continue to use them faster than nature can replace them. Deforestation leads to floods in the monsoon and dry rivers once the rains are over.

What we should implement is Sustainable Development. It is the organizing principle for meeting human needs while at the same time sustaining the ability of natural systems to provide the resources and ecosystem services upon which the economy and society depends. The desirable end result is a society where living conditions and resource use continue to meet human needs without undermining the stability of the natural systems.

The scope of environmental studies includes:

  1. Developing an awareness and sensitivity to the environment and its related problems.
  2. Motivating people for active participation in environmental protection.
  3. Developing skills to find solutions to environmental problems.
  4. Imbibe and inculcate in others the necessity for conservation of natural resources

Needs for awareness Increasing population, urbanization and poverty have exerted pressure on the natural resources and led to degradation of the environment. To prevent the environment from further degradation, the Supreme Court has ordered and initiated environmental protection awareness through government and non-government agencies. Environmental pollution cannot be prevented by laws alone. Public participation is equally important with regards to environmental protection. Environmental Education (EE) is a process of learning by giving an 2 overall perspective of knowledge and awareness of the environment. It sensitizes the society about environmental issues and challenges interested individuals to develop skills and expertise, thereby providing appropriate solutions.

Assignment Questions

  1. Environmental Studies is multidisciplinary in nature.
  2. What are renewable resources? Give examples.
  3. Discuss the need for the awareness of environmental studies programme
  4. What is the importance of studying environmental studies as a core paper
  5. Environmental pollution cannot be prevented by laws alone. Discuss.
  6. Explain sustainable development.
  7. What are natural resources? Give examples.
  8. What are the physical, biological and cultural elements that constitute environment?
  9. List out the scope of environmental studies.
  10. What are non-renewable resources? Give examples



Introduction to Natural Resources

Any material which can be transformed in a way that it becomes more valuable and useful can be termed as resource. In other words, it is possible to obtain valuable items from any resources. Resource, therefore, are the means to attain given ends. The aspect of satisfaction is so important that we consider a thing or substance a resource, as so long it meets our needs. Life on this planet depends upon a large number of things and services provided by the nature, which are known as Natural Resources. Thus water, air, soil, minerals, coal, forests, crops and wild life are all examples of natural resources.

Classification of natural resources

 Depending upon availability of natural resources can be divided into two categories such as (1) renewable and (2) Non renewable resources.

  1. Renewable resources

Renewable resources are in a way inexhaustible resources. They have the ability to replenish themselves by means such as recycling, reproduction and replacement.Examples of renewable resources are sunlight, animals and plants,soil,water,etc.

       2- Non-Renewable Resources

            Non renewable resources are the resources that cannot be replenished once used or     perished. Examples of non renewable resources are minerals, fossil fuels, etc. Resources can also be classified as biotic or a biotic.

  1. Biotic resources

 These are living resources (e.g. forest, agriculture, fish and wild life) that are able to reproduce or replace them and to increase.

  1. Abiotic resources

These are non-living resources (e.g. petrol, land, minerals etc.) that are not able to replace themselves or do so at such a slow rate that they are not useful to consider them in terms of the human life times.

Problems associated with natural resources

  1. The unequal consumption of natural resources

 A major part of natural resources today are consumed in the technologically advanced or ‘developed’ world, usually termed ‘the west’. The ‘developing nations’ of ‘the east’, including India and China, also over use many resources because of their greater human population. However, the consumption of 5 resources per capita (per individual) of the developed countries is up to 50 times greater than in most developing countries. Advanced countries produce over 75% of global industrial waste and greenhouse gases.

  1. Planning land use

Land is a major resource, needed for not only for food production and animal husbandry, but also for industry and growing human settlements. These forms of intensive land use are frequently extended at the cost of ‘wild lands’, our remaining forests, grasslands, wetlands and deserts. This demands for a pragmatic policy that analyses the land allocation for different uses.

  1. The need for sustainable lifestyles

Human standard of living and the health of the ecosystem are indicators of sustainable use of resources in any country or region. Ironically, both are not in concurrence with each other. Increasing the level of one, usually leads to degradation of other. Development policies should be formulated to strike a balance between the two.  


Forest is important renewable resources. Forest vary in composition and diversity and can contribute substantially to the economic development of any country .Plants along with trees cover large areas, produce variety of products and provide food for living organisms, and also important to save the environment.

It is estimated that about 30% of world area is covered by forest whereas 26% by pastures. Among all continents, Africa has largest forested area (33%) followed by Latin America (25%), whereas in North America forest cover is only 11%. Asia and former USSR has 14% area under forest. European countries have only 3% area under forest cover. India’s Forest Cover accounts for 20.6% of the total geographical area of the country as of 2005.

Uses of forests

Forest can provide prosperity of human being and to the nations. Important uses of forest can be classified as under

  • Commercial values
  • Ecological significance
  • Aesthetic values
  • Life and economy of tribal


 Commercial values

  • Forests are main source of many commercial products such as wood, timber, pulpwood etc. About 1.5 billion people depend upon fuel wood as an energy source. Timber obtained from the forest can used to make plywood, board, doors and windows, furniture, and agriculture implements and sports goods. Timber is also a raw material for preparation of paper, rayon and film.
  • Forest can provide food , fibre, edible oils and drugs.
  • Forest lands are also used for agriculture and grazing.
  • Forest is important source of development of dams, recreation and mining.

Life and economy of tribal

Forest provides food, medicine and other products needed for tribal people and play a vital role in the life and economy of tribes living in the forest.

Ecological uses

Forests are habitat to all wild animals, plants and support millions of species. They help in reducing global warming caused by green house gases and produces oxygen upon photosynthesis. Forest can act as pollution purifier by absorbing toxic gases. Forest not only helps in soil conservation but also helps to regulate the hydrological cycle.

Aesthetic values

All over the world people appreciate the beauty and tranquillity of the forest because forests have a greatest aesthetic value. Forest provides opportunity for recreation and ecosystem research.

Over exploitation of forests

Forests contribute substantially to the national economy. With increasing population increased demand of fuel wood, expansion of area under urban development and industries has lead to over exploitation of forest .At present international level we are losing forest at the rate of 1.7 crore hectares annually. Overexploitation also occurs due to overgrazing and conversion of forest to pastures for domestic use.


  1. Forest are burned or cut for clearing of land for agriculture ,harvesting for wood and timber , development and expansion of cities .These economic gains are short term where as long term effects of deforestation
  2. Deforestation rate is relatively low in temperate countries than in tropics If present rate of deforestation continues we may losses 90% tropical forest in coming six decades
  3. For ecological balance 33% area should be under forest cover but our nation has only 20.6% forest cover. e irreversible

Causes of deforestation

  1. Shifting cultivation or jhum cultivation This practice is prevalent in tribal areas where forest lands are cleared to grow subsistence crops. It is estimated that principle cause of deforestation in tropics in Africa, Asia and tropical America is estimated to be 70, 50, and 35% respectively. Shifting cultivation which is a practice of slash and burn agriculture are posses to clear more than 5 lakh hectares of land annually. In India, shifting cultivation is prevalent in northeast and to limited extent in M.P, Bihar and Andhra Pradesh and is contributing significantly to deforestation.
  1. Commercial logging It is a important deforestation agent. It may not be the primary cause but definitely it acts as secondary cause, because new logging lots permits shifting cultivation and fuel wood gatherers access to new logged areas.
  1. c) Need for fuel wood Increased population has lead to increasing demand for fuel wood which is also acting as an important deforestation agent, particularly in dry forest.
  1. d) Expansion for agribusiness With the addition of cash crops such as oil palm, rubber, fruits and ornamental plants, there is stress to expand the area for agribusiness products which results in deforestation.
  2. e) Development projects and growing need for food The growing demand for electricity, irrigation, construction, mining, etc. has lead to destruction of forest. Increased population needs more food which has compelled for increasing area under agriculture crops compelling for deforestation.
  1. f) Raw materials for industrial use Forest provides raw material for industry and it has exerted tremendous pressure on forest. Increasing demand for plywood for backing has exerted pressure on cutting of other species such as fir to be used as backing material for apple in J&K and tea in northeast states.


Water resources are sources of water that are potentially useful. Uses of water include agricultural, industrial, household, recreational and environmental activities. The majority of human uses require fresh water. 97% of the water on the Earth is salt water and only three percent is fresh water; slightly over two thirds of this is frozen in glaciers and polar ice caps. The remaining unfrozen fresh water is found mainly as ground water, with only a small fraction present above ground or in the air. Fresh water is a renewable resource, yet the world’s supply of ground water is steadily decreasing. The depletion is occurring most prominently in Asia, South America and North America. The framework for allocating water resources to water users (where such a frame-work exists) is known as water rights.


Surface water and Ground water use and over exploitation

Surface water is water in a river, lake or fresh water wetland. Surface water is naturally replenished by precipitation and naturally lost through discharge to the oceans, evaporation, evapo transpiration and groundwater recharge. Although the only natural input to any surface water system is precipitation within its watershed, the total quantity of water in that system at any given time is also dependent on many other factors. These factors include storage capacity in lakes, wetlands and artificial reservoirs, the permeability of the soil beneath these storage bodies, the runoff characteristics of the land in the watershed, the timing of the precipitation and local evaporation rates.


All of these factors also affect the proportions of water loss. Human activities can have large and sometimes devastating impact on these factors. Humans often increase storage capacity by constructing reservoirs and decrease it by draining wetlands. Humans increase runoff quantities and velocities by paving areas and channelizing the stream flow. The total quantity of water available at any given time is an important consideration. Some human water users have an intermittent need for water. For example, many farms require large quantities of water in the spring, and no water at all in the winter.


To supply such a farm with water, a surface water system may require a large storage capacity to collect water throughout the year and release it in a short period of time. Other users have a continuous need for water, such as a power plant that requires water for cooling. To supply such a power plant with water, a surface water system only needs enough storage capacity to fill in when the average stream flow is below the power plant’s need. Nevertheless, over long term, the average rate of precipitation within a watershed is the upper bound for average consumption of natural surface water from that watershed. Natural surface water can be augmented by importing surface water from another water-shed through a canal or pipeline. It can also be artificially augmented from any of the other sources; however, in practice the quantities are negligible.




Use and Exploitation A mineral is pure, inorganic substance that occurs naturally in the Earth’s crust. All of the Earth’s crust, except the rather small proportion of the crust that contains organic material, is made up of minerals. Some minerals consist of a single element such as gold, silver, diamond (carbon), and sulphur. Minerals provide the material used to make most of the things of industrial – based society: roads, cars, computers, fertilizers, etc. Demand for minerals is increasing world wide as the population increases and the consumption demands of individual people increase. The mining of earth’s natural resources is, therefore accelerating, and it has accompanying environmental consequences.


More than two-thousand minerals have been identified and most of these contain inorganic compounds formed by various combinations of the eight elements (O, Si, Al, Fe, Ca, Na, K, and Mg) that make up 98.5% of the Earth’s crust. Industry depends on about 80 of the known minerals. A mineral deposit is a concentration of naturally occurring solid, liquid, or gaseous material, in or on the Earth’s crust in such form and amount that its extraction and its conversion into useful materials or items are profitable now or may be so in the future. Mineral resources are non renewable and include metals (e.g. iron, copper, and aluminum) and non-metals (e.g. salt, gypsum, clay, sand, phosphates). Minerals are valuable natural resources that are finite and non-renewable. They constitute the vital raw materials for many basic industries and are a major resource for development. therefore, Management of 18 mineral resources has, to be closely integrated with the overall strategy of development; and exploitation of minerals is to be guided by long-term national goals and perspectives.

Environmental effects of mineral extraction

The scale and level of requirement of minerals have increased manifold in our country and it is heading towards the stage where much larger consumption of minerals will be inevitable to sustain even the minimum growth rate of our economy. It is pertinent to note that out of the total land area of the country (3.29 million sq.kms),the area leased out of mining, as on 1-9-94, was 7126.13 sq.kms. Comprising about 9,213 mining leases, excluding atomic 19 minerals, minor minerals, petroleum and natural gas, this constitutes only about 0.25 per cent of the geographic area of the country and that including atomic minerals and minor minerals it may be around 0.28 per cent of the total area



Food is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ingested by an organism and assimilated by the organism’s cells to provide energy, maintain life, or stimulate growth. Historically, humans secured food through two methods: hunting and gathering and agriculture. Today, the majority of the food energy required by the ever increasing population of the world is supplied by the food industry. Food safety and food security are monitored by agencies like the International Association for Food Protection, World Resources Institute, World Food Programme, Food and Agriculture Organization, and International Food Information Council. They address issues such as sustainability, biological diversity, climate change, nutritional economics, population growth, water supply, and access to food. The food resources are a composite of the goods (the foodstuffs) and the services in commerce and distribution through which these are made available for consumption.

World Food Problems

 Food is essential to survive. There are three degrees of hunger: acute, chronic, and hidden. Famine is caused by food shortage and the inability of people to obtain food. It is usually caused by low food production resulting from drought, other factors, or it could be a result of the inability of a country or its population to afford to buy food. Every year, 15 million children die of hunger. It is estimated that 925 million people in the world do not have enough to eat. The WHO estimates that one-third of the world population is well-fed, one third is under-fed and one-third is starving. There are many factors that have contributed in making food security one of the most important global issues.

An increasing population wants a more varied diet, but trying to grow more food on less land with limited access to water, all the time facing increased costs for fertilizer, and fuel for storage and transport poses great problems for which there are no easy solutions. The available water is decreasing at an alarming rate. This warns us that there is not going to be enough water on the agricultural land that is needed for producing enough food in order to feed the projected population of 9 billion people by 2050. Also, the food prices have skyrocketed in the past few years making it difficult for average earners to afford a three course meal. These effects are witnessed in developing countries that rely heavily on imported food, such as North Africa, Latin America, and Middle East.

Currently, the world food situation is being defined by some new driving forces. These include climate change, globalization, urbanization, energy prices, and income growth as they are responsible in transforming food production, consumption and markets. The security of food in the world depends from the available food supply, the income of the targeted population, accessibility of food, food consumption rate, as well as the amount that can be stocked for future use.

Assignment Questions

  1. What are renewable resources?
  2. Describe non-renewable resources.
  3. State biotic resources.
  4. What are abiotic resources?
  5. What is the commercial values forest?
  6. How forest affects life and economy of tribes?
  7. Explain the ecological uses of forest.
  8. Enumerate aesthetic values of forest.
  9. What is Jhum cultivation?
  10. Write notes on Chipko movement.
  11. What are renewable energy resources? Give examples.
  12. What are non-renewable energy resources? Give examples.
  13. List the advantages of using solar power over other forms of energy.
  14. What is geothermal energy? What are its advantages?
  15. List one advantage and one disadvantage of using wind as energy resource.
  16. What is soil erosion?
  17. What do you mean by equitable use of resources?
  18. What you mean by land as a resource?
  19. List out the important cause of land degradation. What tits effects?
  20. Define desertification.





An ecosystem is an area whose environment is unique and recognizable. Natural ecosystems include forests, grasslands, deserts, wetlands such as ponds, rivers, lakes, and the sea. Man-modified ecosystems include agricultural patterns, and patterns of urban or industrial land use. The ecosystem’s existence is based on its geographical features, such as hills, mountains, plains, rivers, coastal areas or islands. Climatic conditions such as the amount of sunshine, temperature, and rainfall also influence it.

The living portion of the ecosystem is called its biotic component and abiotic component is its non-living portion. All the living organisms in an area live in communities of plants and animals. They interact with their abiotic environment and with each other. Living organisms cannot survive without their non-living environment as this provides food and energy for the former’s survival, Thus, the biotic population and its environment work to create a natural self-sufficient unit known as an ecosystem. Ecosystems are the very base of life itself.

Definition of an ecosystem: A natural functional ecological unit comprising of living organisms (biotic community) and their non-living (abiotic or physio chemical) environment that interact to form a stable self-supporting system.

Ecosystems are divided into terrestrial or land-based ecosystems and aquatic ecosystems.

These form the two major habitat conditions for the Earth’s living organisms.


Stability of ecosystems

 Many ecosystems are relatively stable and less influenced by some degree of human perturbation. Some are weak and quickly destroyed by human activity. Eg: Mountain ecosystems are extremely fragile, because degradation of forest cover contributes to significant soil erosion and changes in river courses. Island ecosystems are also 38 easily affected by human activity which can contribute to the rapid extinction of many of their unique plant and animal species. Some species may have a significant impact on the environment if eliminated. These are called ‘keystone species’. Extinction is caused by land-use changes and other geographical changes. Forests are deforested for timber, wetlands are drained to create more agricultural land and semi-arid grasslands are turned into irrigated fields. The pollution from industries and the waste from urban settings can also lead to poisoning and extinction of several species.



The concept of ecosystem was first put forth by A.G. Tansely in 1935. Ecosystem is an essential unit of ecology. It has both structure and function. The structure is related to species diversity. The more complex the structure, the greater the species diversity within the ecosystem. The functions of an ecosystem are related to energy flow and materials cycling through structural components of the ecosystem. Every ecosystem has two key components from the structural perspective: Abiotic and Biotic


  1. Abiotic components

The non-living factors or the physical environment prevailing in an ecosystem form the abiotic components. They have a significant impact on the structure, distribution, behavior and inter-relationship of organisms. Abiotic components are primarily of two types:


  • Climate Factors which include rain, temperature, light, wind, humidity etc.

( b)Edaphic Factors which include soil, pH, topography minerals etc.


The functions of important factors in abiotic components are given below: Soils are much more complex than simple sediments. They contain a mixture of weathered rock fragments, highly altered soil mineral particles, organic matter, and living organisms. Soils provide nutrients, water, a home, and a structural growing medium for organisms. The vegetation found growing on topsoil is closely linked to this component of an ecosystem through nutrient cycling. The atmosphere provides carbon dioxide for photosynthesis and oxygen for respiration for the organisms found within ecosystems.

The processes of 39 evaporation, transpiration and precipitation cycle water between the atmosphere and the Earth’s surface. Solar radiation is used in ecosystems to heat the atmosphere and to evaporate and transpire water into the atmosphere. Sunlight is also necessary for photosynthesis. Photosynthesis provides the energy for plant growth and metabolism, and the organic food for other forms of life. Most living tissues are composed of a very high percentage of water, up to and even ex-ceeding 90%. The protoplasm of a very few cells can survive if their water content drops below 10% of their saturation level and most are killed if it is less than 30-50% below the saturation level. Water is the medium by which mineral nutrients enter and are trans-lo-cated in plants. It is also necessary for the maintenance of leaf turgidity and is required for photosynthetic chemical reactions. Plants and animals receive their water from the Earth’s surface and soil. The original source of this water is precipitation from the atmosphere.





  1. Biotic Components

The living organisms including plants, animals and micro-organisms (Bacteria and Fungi) that are present in an ecosystem form the biotic components. From nutrition point of view, the biotic components can be grouped into two basic components: (i)Autotrophic components and (ii) Heterotrophic components The autotrophic components include all green plants which fix the radiant energy of sun and manufacture food from inorganic substances. The heterotrophic components include non-green plants and all animals which take food from autotrophs. On the basis of their role in the ecosystem, the biotic components can be classified into three main groups:

(A)Producers (B) Consumers (C) Decomposers or Reducers

(A)Producers: Green plants have chlorophyll with the help of which they trap energy and change it into chemical energy of carbohydrates using simple inorganic compounds, namely, water and carbon dioxide. This process is known as photosynthesis. As the green plants manufacture their own food they are known as Autotrophs (i.e. auto=self, trophos= feeder). The chemical energy stored by the producers is utilized partly by the producers for their own growth and survival and the remaining is stored in the plant parts for their future use.

(B) Consumers:

Animals lack chlorophyll and are unable to synthesize their own food. Therefore, they depend on the producers for their food. They are known as heterotrophs (i.e. heteros= other, trophos= feeder). The consumers are of four types, namely:

 (a) Primary Consumers or First Order Consumers or Herbivores: These are the animals which feed on plants or the producers. They are called herbivores. Eg: rabbit, deer, goat, cattle etc.

(b) Secondary Consumers or Second Order Consumers or Primary Carnivores: The animals which feed on the herbivores are called the primary carvivores. Eg: cat, fox, snake etc.

 (c) Tertiary Consumers or Third Order Consumers: These are the large carnivores which feed on the secondary consumers. E.g. wolf.

(d) Quaternary Consumers or Fourth Order Consumers or Omnivores: These are the largest carnivores which feed on the tertiary consumers and are not eaten up by any other animal: Eg: lion and tiger.

(C) Decomposers or Reducers:

Bacteria and fungi belong to this category. They breakdown the dead organic materials of producers (plants) and consumers (animals) for their food and release to the environment the simple inorganic and organic substances produced as byproducts of their metabolisms. These simple substances are reused by the producers resulting in a cyclic exchange of ma-terials between the biotic community and the abiotic environment of the ecosystem. The decomposers are known as Saprotrophs (i.e., sapros=rotten, trophos=feeder).



In any ecosystem we have the following functional components:

(i)Inorganic constituents (air, water and mineral salts)

(ii)Organisms (plants, animals and microbes) and

(iii)Energy input which enters from outside (the sun)




In the ecosystem, green plants alone are able to trap solar energy and convert it into chemical energy. The chemical energy is locked up in the various organic compounds, such as carbohydrates, fats and proteins, that are present in the green plants. Since virtually all other living organisms depend upon green plants for their energy, the efficiency of plants in any given area in capturing solar energy sets the upper limit to long-term energy flow and biological activity in the community

The food manufactured by the green plants is utilized by themselves and also by herbivores. Herbivores fall prey to some carnivorous animals. In this way, one form of life supports the other form. Thus, food from one trophic level reaches the other trophic level and in this way a chain is established. This is known as the food chain.

Food chains are of three types:

1.\ Grazing food chain

The grazing food chain starts from green plants (autotrophs) and from them, it goes to herbivores (primary consumers) to primary carnivores (secondary consumers) and then to secondary carnivores (tertiary consumers) and so on. The gross production of a green plant in an ecosystem may be utilized in three ways – it may be oxidized in respiration, it may be eaten by herbivorous animals and after the death and decay of producers it may be utilized by decomposers and finally released into the environment. In herbivores, the assimilated food can be stored as carbohydrates, proteins and fats, and transformed into much more complex organic molecules. As in autotrophs, the energy in herbivores also meets three routes-respiration, decay of or-ganic matter by microbes and consumption by the carnivores Likewise, when the secondary carnivores or tertiary consumers eat primary carnivores, the total energy assimilated by primary carnivores or gross tertiary production follows the same course and its disposition into respiration, decay and further consumption by other carnivores is entirely similar to that of herbivores.

2.\ Parasitic food chain

It goes from large organisms to smaller ones without outright killing as in the case of predator.


3.\ Detritus food chains:

50 The dead organic remains including metabolic wastes and exudates derived from grazing food chain are generally termed detritus. The energy contained in detritus is not lost in ecosystem as a whole; rather it serves as a source of energy for a group of organisms called detritivores that are separate from the grazing food chain. The food chain so formed is called detritus food chain



Many food chains exist in an ecosystem, and they are not independent. In an ecosystem, one organism does not depend wholly on another. The resources are shared specially at the beginning of the chain. The marsh plants are eaten by variety of insects, birds, mammals and fishes and some of the animals are eaten by several predators. Similarly, in the food chain

eg: grass→mouse → snakes→owls.

Sometimes mice are not eaten by snakes but directly by owls. This type of interrelationship interlinks the individuals of the whole community. In this way, food chains become interlinked. A complex of interrelated food chains makes up a food web. Food web maintains the stability of the ecosystem. The greater the number of alternative pathways, the more stable is the community of living things.


Ecological Pyramids

The idea of ecological pyramids was advanced by C.E. Eltron (1927). The trophic structure of an ecosystem can be indicated by means of ecological pyramid. At each step in the food chain, a considerable fraction of the potential energy is lost as heat. As a result, organisms in each trophic level pass on lesser energy to the next trophic level than they actually receive. This limits the number of steps in any food chain to 4 or 5. The longer the food chain, the lesser is the energy available for the final members on the chain. Because of this taper-ing off of available energy in the food chain, a pyramid is formed and this is known as the ecological pyramid. The higher the steps in the ecological pyramid, the lower will be the number of individuals and the larger their size.




Assignment Questions

  1. What is an ecosystem?
  2. Explain the structure of an ecosystem.
  3. What are the functions of an ecosystem?
  4. Which are the functional components of an ecosystem?
  5. Write briefly on the biotic components of an ecosystem.
  6. Which are the abiotic components in an ecosystem?
  7. Explain with examples producers, consumers and decomposers.
  8. What do you mean by ‘web of life’?
  9. Explain the energy cycle in an ecosystem.
  10. What do you mean by ecological succession. Explain.
  11. Which are the different types of food chain ?
  12. What do you mean by an ecological pyramid. Name the different types of ecological pyramids.
  13. What is meant by pyramid of numbers?
  14. Which are the different types of forest ecosystems. Give examples for each.
  15. List the characteristic features of forest ecosystems.
  16. Why is a forest ecosystem important to the world?
  17. What is a desert ecosystem ?
  18. Name the different types of a desert ecosystem. Explain each.
  19. Explain lotic and lentic ecosystems.
  20. Write a short note on freshwater ecosystem.
  21. What are pelagic and demersal zones ?

 22.\ What is an estuary?

  1. Part B (15 marks)
  2. Explain its structure and functions.






 It is really amazing , if we divide the whole mother earth into 10 billion parts, it is only one part where life exists and the surprising variety of living organisms which could be about 50 million species are all restricted to just about a kilometer –thick layer of soil, water and air. It is indeed wonderful to see that so much diversity has been created by nature on this earth from so little physical matter. Biodiversity refers to the variety and variability among all groups of living organisms and the ecosystem complexes in which they occur. Biodiversity constitutes the biological wealth.

Importance of biodiversity

Biodiversity conservation, the practice of protecting and preserving the wealth and variety of species, habitats, ecosystems, and genetic diversity on the planet, is important for our health, wealth, food, fuel, and services we depend on. Biodiversity conservation is vital for economic growth and poverty reduction.This has created a great imbalance in nature. Thus, the importance of biodiversity has to be understood and actions have to be taken to maintain all the three levels of diversities.

Biogeographic Classification of India:

India is country of vast biodiversity. It is divided into different regions based on the geography, climate and pattern of vegetation seen and the communities of mammals, birds, reptiles, amphibians, insects and other invertebrates that live in them. Each of these regions contains a variety of ecosystems such as forests, grasslands, lakes, rivers, wetlands, mountains and hills, which have specific plant and animal species. Biogeographic classification of India is the division of India according to biogeographic characteristics. Biogeography is the study of the distribution of species (biology), organisms, and ecosystems in geographic space and through geological time. There are ten biogeographic zones in India.

  1. Trans Himalayan zone.
  2. Himalayan zone
  3. Desert zone.
  4. Semiarid zone.
  5. Western Ghat zone.
  6. Deccan plateau zone.
  7. Gangetic plain zone. 61
  8. North east zone.
  9. Coastal zone.
  10. Islands present near the shore line

Trans-Himalayan region

The Himalayan ranges immediately north of the Great Himalayan range are called the Trans- Himalayas. The Trans-Himalayan region with its sparse vegetation has the richest wild sheep and goat community in the world. The snow leopard is found here, as is the migratory black-necked crane.


 The Himalayas consist of the youngest and loftiest mountain chains in the world. The Himalayas have attained a unique personality owing to their high altitude, steep gradient and rich temperate flora. The forests are very dense with extensive growth of grass and evergreen tall trees. Oak, chestnut, conifer, ash, pine, deodar are abundant in Himalayas. There is no vegetation above the snowline. Several interesting animals live in the Himalayan ranges. Chief species include wild sheep, mountain goats, ibex, shrew, and tapir. Panda and snow leopard are also found here.

Semi-Arid Areas

 Adjoining the desert are the semi-arid areas, a transitional zone between the desert and the denser forests of the Western Ghats. The natural vegetation is thorn forest. This region is characterized by discontinuous vegetation cover with open areas of bare soil and soil-water deficit throughout the year. Thorny shrubs, grasses and some bamboos are present in some regions. A few species of xerophytic herbs and some ephemeral herbs are found in this semi-arid tract. Birds, jackals, leopards, eagles, snakes, fox, buffaloes are found in this region.

Western Ghats

 The mountains along the west coast of peninsular India are the Western Ghats, which constitute one of the unique biological regions of the world. The Western Ghats extend from the southern tip of the peninsula (8°N) northwards about 1600 km to the mouth of the river Tapti (21°N). The mountains rise to average altitudes between 900 and 1500 m above sea level, intercepting monsoon winds from the southwest and creating a rain shadow in the region to their East. The varied climate and diverse topography create a wide array of habitats that support unique sets of plant and animal species. Apart from biological diversity, the region boasts of high levels of cultural diversity, as many indigenous people inhabit its forests.

North-West Desert Regions

This region consists of parts of Rajasthan, Kutch, Delhi and parts of Gujarat. The climate is characterized by very hot, dry summer and cold winter. Rainfall is less than 70 cm. The plants are mostly xerophytic. Babul, Kikar, wild palm grows in areas of moderate rainfall. Indian Bustard, a highly endangered bird is found here. Camels, wild asses, foxes, and snakes are found in hot and arid deserts.


Deccan Plateau

Beyond the Ghats is Deccan Plateau, a semi-arid region lying in the rain shadow of the Western Ghats. This is the largest unit of the Peninsular Plateau of India. The highlands of the plateau are covered with different types of forests, which provide a large variety of forest products. The Deccan plateau includes the region lying south of the Satpura extends up to the southern tip of peninsular India. Anaimudi is the highest peak of this region.The Deccan plateau is surrounded by the Western and the Eastern Ghats. These Ghats meet each other at the Nilgiri hills. The Western Ghats includes the Sahyadri, Nilgiris, Anamalai, and cardamom hills. Many rivers such as Mahanadi, Godavari, Krishna, and Kaveri originates from Western Ghats and flow toward the east.The Eastern Ghats are broken into small hill ranges by river coming from the Western Ghats. Most of these rivers fall into the bay of Bengal.The Godavari is the longest river in the Deccan plateau .Narmada and the Tapi flow westwards and fall into the Arabian sea.

Gangetic Plain

In the North is the Gangetic plain extending up to the Himalayan foothills. This is the largest unit of the Great Plain of India. Ganga is the main river after whose name this plain is named. The aggradational Great Plains cover about 72.4mha area with the Ganga and the Brahmaputra forming the main drainage axes in the major portion. The thickness in the alluvial sediments varies considerably with its maximum in the Gangetic plains. The physio geographic scenery varies greatly from arid and semi-arid landscapes of the Rajasthan Plains to the humid and per-humid landscapes of the Delta and Assam valley in the east.

North-East India

 North-east India is one of the richest flora regions in the country. It has several species of orchids, bamboos, ferns and other plants. Here the wild relatives of cultivated plants such as banana, mango, citrus and pepper can be grown.


The two groups of islands, i.e., the Arabian Sea islands and Bay Islands differ significantly in origin and physical characteristics. The Arabian Sea Islands (Laccadive, Minicoy, etc.) are the foundered remnants of the old land mass and subsequent coral formations. On the other hand, the Bay Islands lay only about 220 Km.


India has a coastline extending over 5,500 km. The Indian coasts vary in their characteristics and structures. The west coast is narrow except around the Gulf of Cambay and the Gulf of Kutch. In the extreme south, however, it is somewhat wider along the south Sahyadri. The backwaters are the characteristic features of this coast. The east coast plains, in contrast are broader due to depositional activities of the east-flowing rivers owing to the change in their base levels. Extensive deltas of the Godavari, Krishna and Kaveri are the characteristic features of this coast. Mangrove vegetation is characteristic of estuarine tracts along the coast for instance, at Ratnagiri in Maharashtra. Larger parts of the coastal plains are covered by fertile soils on which different crops are grown. Rice is the main crop of these areas. Coconut trees grow all along the coast.

Value of Biodiversity

As all the organisms in an ecosystem are interlinked and interdependent, the value of biodiversity in the life of all the organisms including humans is enormous.

  • Loss of biodiversity contributes to climatic change.
  • Forest converts carbon dioxide into carbon and oxygen. Loss of forest covers due to release of carbon dioxide and other gases due to industrialization, contributes to ‘Green House Effect’. This leads to Global warming which results in raise in sea-level submerging the low-lying areas in the world and causing atmospheric changes.
  • Biological diversity is also essential for preserving ecological processes.
  • Tribal communities who directly gather resources from the forest or fisher folk who catch fish in marine or freshwater ecosystems are directly or indirectly linked to the biological variety present in the biosphere.
  • For agricultural communities, biodiversity is used to grow their crops to suit the environment.
  • Urban communities generally use the greatest amount of goods and services, which are all indirectly drawn from natural ecosystems.
  • Preservation of biological resources is essential for the well-being and long-term survival of mankind.


Types of conservation


In situ conservation:

Faced with the conflict between development and conservation, many nations find it unrealistic and economically not feasible to conserve all their biological wealth. Invariably, the number 71 of species waiting to be saved from extinction far exceeds the conservation resources available. On a global basis, this problem has been addressed by eminent conservationists. They identified for maximum protection, certain ‘biodiversity hotspots’ regions with very high levels of species richness and high degree of endemism (that is, species confined to that region and not found anywhere else). Although all the biodiversity hotspots put together cover less than 2 percent of the earth’s land area, the number of species they collectively harbour is extremely high and strict protection of these hotspots could reduce the ongoing mass extinctions by almost 30 per cent. In India, ecologically unique and biodiversity-rich regions are legally protected as biosphere reserves, national parks and sanctuaries. India now has 14 biosphere reserves, 90 national parks and 448 wildlife sanctuaries. India has also a history of religious and cultural traditions that emphasized protection of nature. In many cultures, tracts of forest were set aside, and all the trees and wildlife within were venerated and given total protection. Such sacred groves are found in Khasi and Jaintia Hills in Meghalaya, Aravalli Hills of Rajasthan, Western Ghat regions of Karnataka and Maharashtra and the Sarguja, Chanda and Bastar areas of Madhya Pradesh. In Meghalaya, the sacred groves are the last refuges for a large number of rare and threatened plants.


Ex situ Conservation:

In this approach, threatened animals and plants are taken out from their natural habitat and placed in special setting where they can be protected and given special care. Zoological parks, botanical gardens and wildlife safari parks serve this purpose. There are many animals that have become extinct in the wild but continue to be maintained in zoological parks. In recent years ex situ conservation has advanced beyond keeping threatened species in enclosures. Now gametes of threatened species can be preserved in viable and fertile condition for long periods using cryopreservation techniques, eggs can be fertilised in vitro, and plants can be propagated using tissue culture methods. Seeds of different genetic strains of commercially important plants can be kept for long periods in seed banks. Biodiversity knows no political boundaries and its conservation is therefore a collective responsibility of all nations. The historic Convention on Biological Diversity (‘The Earth Summit’) held in Rio de Janeiro in 1992, called upon all nations to take appropriate measures for conservation of biodiversity and sustainable utilisation of its benefits. In a follow-up, the World Summit on Sustainable Development held in 2002 in Johannesburg, South Africa, 190 countries pledged their commitment to achieve by 2010, a significant reduction in the current rate of biodiversity loss at global, regional and local levels.

Assignment Question

  1. What do you mean by Hotspots?
  2. Name the hotspot centers of India.
  3. What are the reasons of habitat loss caused by humans?
  4. Give the solutions for habitat loss.
  5. What is poaching? How does it affect biodiversity?
  6. Explain endangered species with two examples.
  7. What is Red data book? Give its importance.
  8. Describe endemic species. What is IUCN?
  9. Name the in-situ conservation centers of India.
  10. List the ex-situ conservation centers in India
  11. 1 Enumerate the importance of Biodiversity.
  12. What are the different biogeographic zones of India?
  13. Write notes on species diversity of Himalayan zone.
  14. Briefly describe “Trans Himalayan regions”.
  15. Explain the biodiversity of Western Ghats.
  16. Discuss the biodiversity of Gangetic plains.
  17. Write notes on species diversity of “Islands”.
  18. Enumerate the biodiversity of “Coast”.
  19. What are the consumptive use values of biodiversity?
  20. Describe productive values of biodiversity.
  21. State the social values of biodiversity.
  22. List out the ethical values of biodiversity.
  23. What are the aesthetic values of biodiversity?
  24. List out different hotspots of biodiversity centers in India.
  25. How habitat loss affect biodiversity. Give example.
  26. What is IUCN? Give its objectives.