Environmental Studies Semester 3 PDF

ENVIRONMENTAL STUDIES Semester – III AECC. MATERIAL. 2023 – 2026 BATCH. For Private Circulation Only 1 All rights reserved. No part of this...

ENVIRONMENTAL STUDIES Semester – III AECC. MATERIAL. 2023 – 2026 BATCH. For Private Circulation Only 1 All rights reserved. No part of this work may be reproduced in any form, by any means, without written permission from JAIN (DEEM – TO – BE – UNIVERSITY) The Material is developed for the students of JAIN (Deem – to – be – UNIVERSITY) For Internal Circulation Only Edition: 2018 Revised: 2024 NOTE: THE MATERIAL IS ONLY A DIRECTIVE FOR STUDENTS AND NOT EXHAUSTIVE TOWARDS THE COURSE. THE STUDENTS MUST REFER TO THE REFERENCE BOOKS AND READING LISTS MENTIONED. Developed by: School of Commerce Studies, JAIN (Deemed-to-be UNIVERISTY) Published Printed by: Centre for Virtual Learning & Innovation, JAIN (Deemed-to-be UNIVERISTY) For Private Circulation Only 2 Program: Bachelor of Commerce (B.Com/BMS) Course : ENVIRONMENTAL STUDIES Code : 22ENVIOVE2 Course Credits No. of Hours per Week Total No. of Teaching Hours 3 Credits 3 Hours 45 Hours Pedagogy: Classroom lecture, tutorials, Group discussion, Seminar, Case studies & field work etc., Course Outcomes: On successful completion of the course, the Students will be able to  CO-1: Classify the importance of Environment and to protect the eco systems mainly forests, rivers and lakes etc.  CO-2: Demonstrate on sustainable development by reducing the use of non-renewable resources and increasing renewable energy resources with the support of biodiversity services.  CO-3: Discuss on the harmful effects of various pollution to people around and help to reduce pollution.  CO-4: Recognize the importance of global warming, ozone layer depletion and its impacts with the understanding of various environmental laws.  CO-5: Examine the resettlement and rehabilitation on environment through Supporting the government and the NGO`s in protecting our valuable flora, fauna and endangered species. Syllabus: Hours Module No. 1: Introduction to environmental studies 2 Hours Multidisciplinary nature of environmental studies; Scope and importance; Concept of sustainability and sustainable development. Module No. 2: Ecosystem 5 Hours What is an ecosystem? Structure and function of ecosystem; Energy flow in an ecosystem: food chains, food webs and ecological succession. Case studies of the following ecosystems: a) Forest ecosystem b) Grassland ecosystem c) Desert ecosystem d) Aquatic ecosystems (ponds, streams, lakes, rivers, oceans, estuaries) Module No. 3: Natural Resources: Renewable and Non‐renewable Resources 7 Hours Land resources and landuse change; Land degradation, soil erosion and desertification; Deforestation: Causes and impacts due to mining, dam building on environment, forests, biodiversity and tribal populations; Water: Use and overexploitation of surface and ground water, floods, droughts, conflicts For Private Circulation Only 3  over water (international & inter‐state) - Energy resources: Renewable and non renewable energy sources, use of alternate energy sources, growing energy needs, case studies. Module No. 4: Biodiversity and Conservation 7 Hours Levels of biological diversity : genetic, species and ecosystem diversity; Biogeographic zones of India; Biodiversity patterns and global biodiversity hot spots - India as a mega biodiversity nation; Endangered and endemic species of India - Threats to biodiversity : Habitat loss, poaching of wildlife, man‐wildlife conflicts, biological invas ions; Conservation of biodiversity : In-situ and Ex-situ conservation of biodiversity- Ecosystem and biodiversity services: Ecological, economic, social, ethical, aesthetic and Informational value. Module No. 5: Environmental Pollution 5 Hours Environmental pollution: types, causes, effects and controls; Air, water, soil and noise pollution - hazards and human health risks - Solid waste management: Control measures of urban and industrial waste -Pollution case studies. Module No. 6: Environmental Policies & Practices 7 Hours Climate change, global warming, ozone layer depletion, acid rain and impacts on human communities and agriculture; Environment Laws: Environment Protection Act; Air (Prevention & Control of Pollution) Act Water (Prevention and control of Pollution) Act; Wildlife Protection Act; Forest Conservation Act. International agreements: Montreal and Kyoto protocols and Convention on Biological Diversity (CBD); Nature reserves, tribal populations and rights, and human wildlife conflicts in Indian context. Module No. 7: Human Communities and the Environment 7 Hours Human population growth: Impacts on environment, human health and welfare. Resettlement and rehabilitation of project affected persons; case studies. Disaster management: floods, earthquake, cyclones and landslides. Environmental movements: Chipko, Silent valley, Bishnois of Rajasthan. Environmental ethics: Role of Indian and other religions and cultures in environmental conservation. Environmental communication and public awareness, case studies (e.g., CNG vehicles in Delhi). Module No. 8: Field Work 5 Hours Visit to an area to document environmental assets: river/ forest/ flora/fauna, etc. Visit to a local polluted site‐Urban/Rural/Industrial/Agricultural. Study of common plants, insects, birds and basic principles of identification. Study of simple ecosystems‐pond, river, Delhi Ridge, etc. For Private Circulation Only 4  Reference Books 1. Carson, R. 2002. Silent Spring. Houghton Mifflin Harcourt. 2. Gadgil, M., & Guha, R. 1993. This Fissured Land: An Ecological History of India. Univ. of California Press. 3. Gleeson, B. and Low, N. (eds.) 1999. Global Ethics and Environment, London, Routledge. 4. Gleick, P. H. 1993. Water in Crisis. Pacific Institute for Studies in Dev., Environment & Security. Stockholm Env. Institute, Oxford Univ. Press. 5. Groom, Martha J., Gary K. Meffe, and Carl Ronald Carroll. Principles of Conservation Biology. Sunderland: Sinauer Associates, 2006. For Private Circulation Only 5  INDEX Sl. No. Module Page No. 1 Module – 1 7-13 2 Module – 2 14-30 3 Module – 3 31-59 4 Module – 4 60-74 5 Module – 5 75-119 6 Module – 6 120-143 7 Module – 7 144-151 For Private Circulation Only 6  Module 1 ENVIRONMENT SCIENCE- A MULTIDISCIPLINARY SUBJECT Structure Objectives 1.1 Introduction 1.2 What exactly is environment? 1.3 Is environment a multidisciplinary subject? 1.4 Global, local and individualistic nature of environment 1.5 Need of public awareness. 1.6 Evolution of sustainable development 1.7 Summary 1.8 Questions 1.9 Answers Objectives At the end of the unit you will be able to: >Understand environment >Its multidisciplinary nature > Its relevance at individual, local and global levels 1.1 Introduction Chinese proverb, 'If you plan for one year, plant rice, if you plan for ten years, plant trees, if you plan for hundred years, educate people' This education has to be in terms of our environment and its management to be able to sustain our environment and consequently quality of life. 1.2 What exactly is environment? Environment in one word means surroundings (obviously of organisms) Environment is a collective term embracing all the conditions in which an organism lives, for example, light, temperature, water and other organisms. Some components of environment like soil water etc serve as resource while other components such as temperature, light etc. act as regulatory factor (to the organism). All components of environment are interlinked and interdependent. The environment in relation to man is the sum total of all- social, economical, biological, physical or chemical factors which constitutes the surroundings of man, who is both creator and moulder of his environment. It is implicit in the above two descriptions of environment that there can be two types of environment; environment in natural form without the interference of man is called natural environment and environment changed or modified by the interference of human beings is called man-made environment. For Private Circulation Only 7 1.4 Is Environment a Multidisciplinary subject? Environmental studies deal with every issue that affects an organism and so it is essentially a multidisciplinary approach that brings about an appreciation of our natural world and human impacts on it. It is an applied science as it seeks practical answers in making human civilization sustainable on the earth's finite resources. Its components include 1. Life Sciences including botany, zoology, microbiology etc help in understanding the biotic and abiotic components of the environment. 2. Geosciences are the sciences related to the planet Earth and include topics of geology, oceanography, hydrology, soil science etc Apart from these physics, chemistry and atmospheric sciences together help us understand the physical and chemical structure and also the mass and energy transfers in the abiotic environment. 3. Engineering includes civil, chemical, hydraulics, nanotechnology which help provide solutions to environmental problems. 4. Health is vital and it is important to be aware how our environment affects our health. 5. Anthropology is the study of humanity and anthropological insights could help in understanding the nature of the manmade environment and also deals with finding solutions to the problems caused by man’s intervention in nature. 6. Economics and sociology provide inputs in dealing with socio-economic aspects associated with various development activities 7. Statistics, mathematics and computer science are tools required in environment modeling 8. Philosophy is required to understand and enhance the spiritual environment, the inner health and peace of the individual which can help in the holistic development of the society. 9. Environment education and mass communication help in spreading environmental awareness For Private Circulation Only 8  Environment is a closely and intricately woven network of components and functions. Any change affects all the components of the environment. The various levels at which the changes affect, reflect the global, local or individualistic nature of environment. To explain how any act can have far reaching effects, let us consider the example of the far reaching effects of the isolated act of damage to the forests of a hilly region. Cutting down trees destroys the habitat of a variety of flora and fauna thus reducing biodiversity which is a wealth to the field of medicine. The deforestation on hills also leads to erosion of soil from these hills during heavy rains. These hills are catchments of streams and rivers and the soil that is carried by the streams and rivers is deposited in the bottom of rivers which in turn raises the river bottom (which is called siltation). The disastrous floods of 1978 and 1980 which inundated almost all north India can to a large extent was due to siltation of river beds. The siltation was a result of felling of soil holding trees in the mountains affecting the length and breadth of the Indo-Gangetic Plain. As the river bears with it its load of silt and mud out to the sea, harbors too are silted up, making it necessary to continuously carry out expensive dredging operations. All this loss and expense affects the economy of the country. Apart from all this, ground water is also being lost because water falling on hills can be halted and can get percolated into the earth only if there is a good cover of trees. Thus a single act of cutting of trees on hills has far reaching effects- endangers various rare flora and fauna; erosion of soil results in siltation of river and harbors which in turn leads to frequent floods and dredging needs in harbors. Consequently there is loss of soil, ground water, production, wealth. There are environmental issues or changes which may occur at any place but affects the globe as a whole and such issues reflect the global nature of environment. For example, the green house gases in any region affects the globe as a whole by increasing the over all temperature over the years, that is it aggravates the process of global warming. CFCs contributed by any act on earth anywhere effects the whole globe by ultimately reaching the ozone layer and depleting it. Dwindling of energy resources like petroleum would make us dependants on nuclear fuels until they reach the stage of exhaustion too. Thus depleting energy resources is a global problem. Dwindling biodiversity would make us lose on valuable plants which could have been useful in the field of medicine, and so to the whole humanity. Issues like ground water pollution, hydroelectric projects, impacts of mining etc effect a local area. These are local issues with respect to environment. For example the region of Hinkley in California was affected by hexavalent chromium in its groundwater percolated from the unlined ponds from the cooling towers of PG&E. The wastewater percolated into the groundwater, affected an area near the plant approximately two miles long and nearly a mile wide. It adversely affected the health of people who had been living in that area. Thus the factors that constitute and influence the local environment reflect the local nature of environment. Individually each person needs clean air, clean water, healthy food, clean and safe surroundings. The nature of the water, food and air that an individual uses or interacts with constitutes the individual nature of the environment. Any issues affecting our immediate surroundings thus affect us. Thus, the most mundane needs and interactions of man are related to our environment, so it becomes essential to understand and preserve our environment at the individual, local and global levels. 1.5 Need for Public Awareness In reality, environment consciousness is more difficult to incorporate in the psyche of people as economic concerns make people blind to the effects that a particular economic activity can have on the environment. For example poachers know for a fact that there are only a few hundred tigers left in the forests of India, but they are more concerned about their economic needs. It is important to educate the people that sometimes the adverse effects on us of the altered environment is not experienced or noticed until a threshold is For Private Circulation Only 9 crossed. The public has to be educated about the fact that if we are degrading the environment we are actually harming our own selves, our own health and our own future. A passion for environment is essential to develop a change in the consumption pattern of the populace (for example all people aware of the problems of pollution still travel by private vehicle, do not switch off their vehicles at traffic signals, use plastic covers extensively). Care for environment is required to push a change in the individual consumption pattern which is possible only through education. Environment study necessarily requires developing awareness of what is going on in the world. The holistic approach to teaching of environment science in schools and holistic study of each topic (understanding interconnections) is required to develop the ability of problem solving, as the real purpose of studying environment science is to be able to find solutions. The intelligence of the student pool is required to find new ways out of the current deplorable situation. 1.6 EVOLUTION OF SUSTAINABLE DEVELOPMENT Sustainable Development stands for sustainability and it represents an approach to development which is concerned with such fundamental human concerns like poverty, environment, equality, democracy, development and peace. The term ‘Sustainable Development was coined by Barbara Ward’, the founder of the International Institute for Environment and Development, who made the point that development and environment protection must be linked. The Sustainable Development was popularized in 1987 by the World Commission on Environment and Development through the Brundtland Report. This Report, which was entitled, ‘Our Common Future’, produced the most widely accepted definition of Sustainable of the present without compromising the ability of future generations to meet their own needs. In 1992, the U.N. Conference on Environment and Development (UNCED) in Rio de Janeiro, the Earth Summit, called for Sustainable Development , “ to ensure socially responsible economic development while protecting the resource base and the environment for the benefit of future generation”. 1.6.1 Definition of Sustainable Development Sustainable Development, is thus a process of economic development, which aims at maintaining the quality of life of both present and future generations without harming natural resources and environment. It is the process of development which can be sustained over a long period of time without causing fall in the quality of life of future generations. The Environment provides Life on Earth. The Environment is the Part and Parcel of the Society. As it decides the very existence, growth and development of mankind and all its activities. As it is a Multidisciplinary area of study which has several factors that prevails upon the Social Lives of the People such as – Economic, Social, Ethical, Scientific, Technological, Spiritual, etc. For Private Circulation Only 10  Due to the Development in Science and Technology, there is a Change in the Behaviour of people. As it has brought alarming consequences on the people. So far, man has indulged in exploitation of nature and its resources. But now there is environmental degradation and depletion. It in turns, affect the quality of life of people. We have to learn to live within our planetary means. For the sustainable development of humanity, the people have to change their approach. The Government has to design economic policies and developmental activities to nurture the environment. The Developmental activities and environmental safety can be ensured through sustainable development. 1.6.2 In the following areas, Sustainability has to be adopted. a. The Climatic Changes. b. Biodiversity. c. Disposal of hazardous and toxic wastes. d. Disposal of pollution – Industrial Effluents all must be properly managed and treated 1.6.3 The following nine elements /aspects were recommended by Dr.M.S.Swaminathan 1. Land 2. Water 3. Energy 4. Nutrient supply 5. Genetic diversity 6. Pest management 7. Post-harvest system 8. Systems approach 9. Location – specific research and development. The population has to be kept under control. At Global Level, a political transition should take place on mutually agreed objectives among nations. 1.6.4 The environmental issues affecting Sustainable Development: Agricultural Occupation – By encouraging high-yielding varieties, development of aquaculture fish farming, etc. the food problem has to be solved. People must change towards non-conventional sources like Solar, wind, tidal, etc. to solve the power crisis. The Government should take steps to control pollution. To check pollution, the waste management practices should be undertaken. Development of Natural Vegetation. For Private Circulation Only 11  1.6.5 The following steps are vital for sustainable development:  To provide clean and hygienic living and working conditions for the people.  To undertake Research and Development on local environmental issues.  Safety devices must be provided in all factories.  To ensure better treatment method of salvaging hazardous industrial wastes.  To create substitutes for proven hazardous materials based on local resources needs.  To introduce environmental education as part of school and college curricula.  To practice non-conventional sources of energy like solar energy, wind energy, tidal energy.  The companies must produce eco-friendly products. 1.7 Summary >Study of a number of subjects is required to understand and find solutions for environmental problems >What we do to our environment actually comes back to us as all components of environment are interconnected >Creating awareness about environment and the interconnectedness of all components is essential to replace indifference to environment with proactive interest. 1.8 Terminal Questions Multiple Choice Questions 1. Environmental science deals with * ?* A. Plants B. Animals C. all aspects of all living beings and their association. D. Relationship between animals & plants. 2. Biosphere contains * * A. plants B. All living beings C. Animals D. Insects 3. Rivers, oceans are part of * * A. Hydrosphere B. Mesosphere C. Aqua sphere D. water sphere 4. A natural environment in which an organism lives is called* ?* A. Hemisphere B. biosphere C. Ecoserene D. Habitat 5. Which new organisation came into existence after the Earth Summit of 1992? A. UN Commission of Inclusive Development B. Inter-governmental Panel on Climate Change C. UN Commission on Sustainable Development D. UN Framework Convention on Climate Change For Private Circulation Only 12 Activities 1. From your home to your college, note down the various features, peculiarities and any major problem of your environment. 2. What would you need to study to resolve that particular problem? 1.9 Answers Terminal Questions Multiple Choice Questions 1.C 2.B 3.A 4.D 5.C References Our Environment , Laeeq Futehally, 1988, National Book Trust, India http://www.newagepublishers.com/samplechapter/001426.pdf For Private Circulation Only 13  Module 2 ECOSYSTEM Structure Objectives 2.1 Introduction 2.2 Concept of Ecosystem 2.3 Structure and Function of Ecosystem 2.4 Ecological succession 2.5 Major types of ecosystem 2.6 Summary 2.7 Questions 2.8 Answers Objectives At the end of the unit you will be able to: > understand how nature functions in relation to its various components > understand different types of ecosystems and their similarities and differences. 2.1 Introduction Let us a little permit Nature to take her own way; she better understands her own affairs than we. ~Michel de Montaigne (translated) Our Earth is the only known planet with life. We have to understand its delicate balance, develop respect for its complexity and learn to obey it realizing that nature knows better than we do just as parents know better than a little child. Anthropogenic interference due to developmental activities affects the delicate balance that is maintained in the units of self dependent systems in the biosphere called as ecosystems. This is because in these units the living and non-living environment works in complete coordination for the well being of the whole unit. It is important to understand this coordination to fathom how man is working against this otherwise perfect system and destroying it in small and big ways. Thus endangering his own survival. 2.2 Concept of Ecosystem An ecosystem can be defined as a biological environment consisting of all the organisms living in a particular area interacting with each other, as well as with all the nonliving, physical components of the environment, such as air, soil, water, and sunlight, exchanging energy and matter. That is, it is all the organisms or in other words the biological communities of different species in a given area and its physical environment or abiotic components of the area. The study of ecosystems is called ecology. The term ecology was coined in 1869 (by Earnst Haekal) much before the term ecosystem. It is derived from the Greek word Oikos (Home) and Logos (study) and so ecology meant the study of organisms in their natural environment or home interacting with their surroundings. The unit of study of ecology was later described by Tansley (1935) as ecosystem. Ecosystems have become particularly important politically, since the Convention on Biological Diversity (CBD) - ratified by 192 countries – which defines "the protection of ecosystems, natural habitats and the maintenance of viable populations of species in natural surroundings" as a commitment of ratifying countries. This has created the political necessity to spatially identify ecosystems and somehow distinguish among them. The CBD defines For Private Circulation Only 14 an "ecosystem" as a "dynamic complex of plant, animal and micro-organism communitiesand For Private Circulation Only 15 their non-living environment interacting as a functional unit". Some of the major ecosystems are forest ecosystem, grassland ecosystem, desert ecosystem, aquatic ecosystems etc. Though there are obviously various differences in different ecosystems, the basic structure and functions are common. 2.3 Structure and function of Ecosystem Ecosystems show large variations in size, structure, composition etc. However all the ecosystems are characterized by certain basic structural and functional features which are common. The basic structural components of an ecosystem are biotic and abiotic components. That is the ecosystem can be viewed as a series of biotic components that are linked together and thus interact with one another exchanging energy and matter, and being influenced by other abiotic factors. The fact that ecosystem components are linked indicates that disturbances to one component impact on all other components of the ecosystem to varying degrees. A. Structure of ecosystems – This can be summarized in four ways a. Trophic levels (Biotic Components) b. Abiotic Components c. Trophic relationships d. Ecological pyramids a. Trophic levels - Ecosystems have a basic structure according to how different populations acquire energy flow, where energy flow is a function of ecosystems. Species obtaining energy in a similar way are grouped into trophic levels. There are three primary trophic levels: 1. Primary producers 2. Consumers 3. Decomposers Primary producers are autotrophic organisms (primarily green plants) capable of photosynthesis making food for themselves and indirectly for other components. In terrestrial ecosystems the autotrophs are usually rooted plants, while in aquatic ecosystems shallow waters have rooted plants and deep waters have phytoplankton’s as the major autotrophs Consumers are heterotrophic organisms dependent on other organisms for food. Consumers can be subdivided into more specific trophic levels.Those feeding directly on producers are called primary consumers (herbivores) like rabbit, deer for terrestrial and protozoa, many mollusk species for aquatic ecosystems. The secondary and tertiary consumers (carnivores) eat other consumers. For e.g. frog, tiger for terrestrial ecosystems and fishes for aquatic ecosystems. Decomposers are organisms that obtain energy and nutrients from remains of dead producers and consumers. Decomposers are primarily bacteria and fungi which are extremely important in the process of nutrient cycling. Composition of Species: For each ecosystem, the species composition in these three basic structural levels of producers, consumers and decomposers will be different. For example, pond ecosystem will have different composition of species in the three levels compared to marine ecosystem. A desert will have fewer species as compared to the variety of species in a forest ecosystem. Thus Species composition differentiates ecosystems. b. Abiotic Components – The abiotic components are air, water, salts, light, temperature, nutrients etc. These are basic components in the structure of every ecosystem. In deserts, temperature and light will be in excess, but with scarcity of water. In deep sea, light would be limited. But all these components are vital and the species composition is affected by these abiotic factors. Nutrients such as N, P and Ca, necessary for the growth of living organisms are accumulated in the biomass and the abiotic components like the soil. The amount of these nutrients present in the soil at any given time is known as standing state. Different ecosystems have different standing state of nutrients. The standing state of nutrients may vary at different time even in the same ecosystem. For Private Circulation Only 16 c. Trophic relationships - Ecosystems also have a basic structure according to trophic relationships. This is the relationship of "who-eats-whom" in an ecosystem and is a food chain. More often, however, food chains are not isolated from one another but rather are "cross-linked" into more complicated structures called food webs. Thus a food chain can be defined as a linear series of organisms dependent on each other for food, resulting in the function of transfer of energy in an ecosystem. Example Grass is eaten by sheep, which in turn is eaten by a lion. A food web can be defined as an interconnected set of food chains in the ecosystem. For example a mouse in the field may eat several types of seeds and be preyed upon by several different carnivores animals. But each of these carnivores animals may consume not just the mouse but several different types of prey and so on, thus forming an interconnected network of species. The two most important functions of energy flow and nutrient cycling takes place through this basic structure of food chains and food web. The food chains are also significant in that it helps in maintaining and regulating the population size of different animals and thus maintain ecological balance. As the diversity (e.g. number of species) in the ecosystem increases, the complexity of these food webs also increases and as complexity increases so does stability. e.g. disturbance or extinction of one or two species can be compensated for. In simple food webs or chains, extinction of one species may lead to the collapse of the entire system. Fig2.1: Trophic Relationships Human agricultural ecosystems are good examples of simple, unstable ecosystems. Monocultures of single crop plants consumed by livestock and/or humans are the single food source of insects in the ecosystem making the system unstable and because they are unstable, they require additional energy inputs to prevent them from collapsing e.g. insecticides, herbicides, fertilizers, irrigation water, etc. Irish potato famine is an example of the instability of human agricultural ecosystems. d. Ecological Pyramids- Another way to summarize the structure of trophic of ecosystems is in the form of ecological pyramids for the trophic relationships. Ecological pyramids are graphic representation of the For Private Circulation Only 17 structure of trophic and function of an ecosystem, starting with producers at the base and successive trophic levels leading to the apex. These are mostly upright but can be inverted or even urn shaped. Ecological pyramids can be based on three different kinds of information related to the trophic relationships. These are as follows: 1. Pyramid of numbers – It is based on numbers of individuals in each trophic level. For example the producers in the grasslands are grasses which are small in size and large in number thus forming a broad base. The herbivores in this ecosystem are insects while tertiary carnivores are hawks or other birds which are gradually less and less in number, thus forming an upright pyramid. In forest ecosystem the producers are big trees which are less in number, where the birds, insects etc that feed on the trees are more in number forming a broader middle structure. The secondary consumers like lizards, snakes, fox etc which feed o these are lesser in number and thus the pyramid is urn shaped. For parasitic food chain of few big trees with fruit eating birds harboured on them, which in turn have higher number of lice, bugs etc as parasites growing on them, while a still greater number of hyperparasites like microbes feeding on them, makes for an inverted pyramid of numbers. 2. Pyramid of biomass – It is based on weight of living material in each trophic level. For example in a forest the producers (trees) accumulate a huge biomass while the total biomass of the consumers feeding at each successive level decreases resulting in a broad base and narrowing top, that is an upright pyramid. Whereas for a pond ecosystem the producer are phytoplanktons which have much less biomass as compared to herbivores (zooplanktons, insects) and carnivores (small fish) and tertiary carnivores (big fish). Thus the pyramid takes an inverted shape with narrow base and broad apex. 3. Pyramid of energy – It is based on energy content of each trophic level. As energy is always lost at each step of a food chain, the pyramid of energy is always upright. The energy loss in the form of heat, respiration etc at each trophic level is as high as 90%, that is only about 10% of the energy is passed on to the next trophic level. This would mean that if there were a 1000 units of energy at the producers level the primary consumers would receive 100 units of energy, the secondary consumers would receive 10 units of energy, and the tertiary consumer would receive 1 unit of energy. That is why it takes a lot of producers to support a few top consumers. Hence the pyramid of energy is the best representation of the trophic relationship. This pyramid helps to demonstrate the loss of energy from one level of the food chain to the next level. Fig 2.2.a. Basic pyramid of trophic relationship (source: Utah State Office of Education) Lion, Tiger Snakes, foxes, lizards Insects, birds Trees For Private Circulation Only 18  Fig 2.2. b. Pyramid of Numbers for forests Big fish Small fish Insects Phytoplanktons Fig 2.2.c Pyramid of Biomass for pond Values for all the pyramids based on the three types of information, thus generally get smaller from producers to primary consumers to secondary consumers, etc (hence takes a pyramidal form when represented) where major exceptions are Forest ecosystems showing urn shaped pyramid of numbers and parasitic food chains showing inverted pyramid of numbers. Pond ecosystems showing inverted pyramid of biomass. The pyramid of energy has no exceptions being always upright. The three pyramids (of number, biomass and energy) drawn for each ecosystem thus gives a holistic representation of trophic relationships, or the structure of the particular ecosystems, is based on the function they perform. (Refer fig.) B. Functions of Ecosystem- Interactions between ecosystem components involve two general processes or functions: 1. Energy flow. 2. Nutrient cycling. 1. Energy Flow – Energy flow is an important function that sustains the ecosystem but the energy does not cycle and so needs a constant input. Energy flow is a one-way process in ecosystems The sun is the ultimate source of energy for most ecosystems, which provides for the essential constant input of energy. This is called radiant energy in the form of electromagnetic waves, as is sunlight. Primary producers capture a fraction of energy in sunlight striking the earth and convert it into chemical energy (carbohydrate) that is stored in their tissues. This is fixed energy, which is potential chemical energy bound up in various organic substances, which are broken down in order to release their energy content. Energy in tissues of primary producers is transferred to consumers as each consumes tissue of other organisms. Each organism oxidizes the organic substances of the first to liberate energy to synthesize its own cellular constituents, thus further decreasing the useful energy at each step. About 90% - 95% of energy present in one component is lost as heat at each transfer. The fixation of energy and its flow thus obeys the two laws of thermodynamics where the first law states that energy can neither be created nor destroyed. It can only be transformed from one form to another. And the second law states that every transformation of energy is accompanied by a simultaneous degradation of energy from concentrated form to dispersed form. Energy flow is thus a very inefficient process and very little energy is left when decomposers get to it. There are two important energy flow models. a. Single channel energy flow model- It depicts the energy flow in a grazing food chain which starts from green plants and ends to carnivores passing herbivores. This is depicted using narrowing pipes to depict the gradual loss of energy at every level and using smaller boxes to depict the decreasing stored energy that is biomass (B). The incident energy (I), energy assimilated (A), loss of energy, that is excreted or not utilized energy (NU), the energy loss or respiration(R) and the energy used for production (P) is depicted. (Refer fig 3.3) For Private Circulation Only 19 Fig2.3: Single channel shaped Enegy Flow Model b. Y-shaped energy flow model- It was E.P. Odum who noted that food chain may begin with live parts of plants or dead parts of plants parts which led to his conclusion that in nature two basic food chains the grazing food chain and detritus food chain operate, in the same ecosystem. The detritus that is dead matter derived from the grazing food chain serves as source of energy for detritivores or decomposers that are separate from the grazing food chain and generally termed as the detritus food chain. The significant part in Y-shaped model is that the two food chains are not isolated from each other. Refer fig 3.4, for a representation of the Y shaped energy flow. Y-shaped energy flow model is more realistic and practical than the single-channel energy flow model because of the following points :(i) It conforms to the basic stratified structure of ecosystems.(it) It separates the two chains i.e. grazing food chain and detritus food chain in both time and space.(iii) Microconsumers (e.g. bacteria, fungi) and the macroconsumers (animals) differ greatly in. size- metabolism relations in two models. In some ecosystems either grazing or detritus food chain may predominate. Grazing food chain predominates in marine ecosystems as primary production in the open sea is limited and much of it is eaten by marine herbivores leaving little dead matter for the detritus food chain whereas in forest ecosystem the huge quantity of biomass produced cannot be all consumed by herbivores, leaving a large proportion of biomass in the form of litter for the detritus food chain. The basic components of an energy flow model can be examined in a generalized model of Y-shaped energy flow called the Universal model given by E.P. Odum 1983. This model is applicable to both terrestrial and aquatic ecosystems. It is applicable to any living component, an individual, a population or a trophic group. (Refer fig 3.5) For Private Circulation Only 20 Fig2.4: Simple Enegy Flow diagram representing both the grazing and the detritus(dead matter) food chain Fig2.5: Generalised Y shaped Enegy Flow Model (Universal Model) It can be concluded form the energy flow, that shorter the food chain, greater would be the available food energy as with the increase in length of the food chain, there is a correspondingly greater loss of energy. It also implies that a larger population of people can be supported if people shorten the food chain by eating grains directly rather than eating animals that feed on grains. Although fruit and vegetable-sources of protein are more often lower in one or more essential amino acids than animal sources, like lysine, and to a lesser extent methionine and threonine. Yet the plant sources of protein can be adequate for adult needs even with any one of the legume, cereal, nut, seed, or fruit food groups. 2. Nutrient Cycling - Now, let's consider nutrient cycling in ecosystems and see how it is in contrasts to energy flow. Nutrients are molecules required by living organisms e.g. carbon, nitrogen, phosphorus. Unlike energy, there is no major input of nutrients from outside the ecosystem. Thus, nutrients are used over and over again which would mean that the carbon, nitrogen, etc. atoms in our body have been used over and over again in ecosystems. Nutrients move through ecosystems by way of biogeochemical cycles which by name indicate that these cycles include biological, geological and chemical processes. Major cycles are Nitrogen, Carbon and Phosphorous cycle. Nutrients exist in either a reservoir or exchange pool: reservoir is the storehouse of For Private Circulation Only 21 Nutrients. The nutrients in the reservoir are not directly available to organisms in the ecosystem e.g. reservoirs for carbon include limestone, coral reefs, and fossil fuels such as coal and natural gas. Reservoir of phosphorous are rocks, fossils etc. Exchange pool is the source of nutrients in a form that can be taken up by primary producers e.g. carbon in the form of atmospheric carbon dioxide is the exchange pool form.. From Phosphate rocks the phosphorous becomes available as dissolved phosphorous due to erosion. Nutrients tied up in biomass are released by decomposition back into exchange pool. Nutrients are taken up by primary producers and passed from trophic level to trophic level like energy but is not lost as heat, rather are incorporated into biomass of each trophic level. In obtaining energy from dead organic material, decomposers release nutrients back into exchange pool. Some of this dead material may not be decomposed and nutrients may become part of reservoir -- e.g. carbonification of dead organic materials not decomposed produces reservoir forms such as natural gas, oil and coal. 2.4 Ecological Succession "Ecological succession" is the observed process of change in the structure of species of an ecological community over a period of time. Within any community some species may become less abundant over some time interval, or they may even vanish from the ecosystem altogether. Similarly, over some time interval, other species within the community may become more abundant, or new species may even invade into the community from adjacent ecosystems. This observed change over a period of time in what is living in a particular ecosystem is "ecological succession". It occurs because ecosystems are not static in nature, and is triggered by changes in the environment. The original environment may have been optimal for the first species of plant or animal, but the newly altered environment is often optimal for some other species of plant or animal. Under the changed conditions of the environment, the previously dominant species may fail and another species may become ascendant. Does ecological succession ever stop? In ecological succession there is the concept of the "climax" community. The climax community represents a stable end product of the successional sequence. Its apparent that the structure of the species and composition will not change much over observable time. To this degree, we could say that ecological succession has "stopped". We must recognize, however, that any ecosystem, no matter how inherently stable and persistent, could be subject to massive external disruptive forces (like fires and storms) that could re-set and re-trigger the successional process. As long as these random and potentially catastrophic events are possible, it is not absolutely accurate to say that succession has stopped. Also, over long periods of time ("geological time") the climate conditions and other fundamental aspects of an ecosystem change. These geological time scale changes are not observable in our "ecological" time, but their fundamental existence and historical reality cannot be disputed. No ecosystem, then, has existed or will exist unchanged or unchanging over a geological time scale. Process of Succession Thus Ecological Succession can be elaborately defined as an orderly process of change in the community structure and function with the passage of time, mediated through modifications in the physical environment and ultimately culminating in a stabilized ecosystem known as climax. The whole sequences of communities which are transitory are known as Seral stage or seres whereas the community established first of all in the area is called a pioneer community. The process of succession takes place in a systematic order of sequential steps as follows. 1 Nudation - It is the development of a bare area without any life form. The bare area may be caused due to landslides, volcanic eruptions, drought, glaciers, frost, overgrazing, outbreak of diseases, agricultural, industrial activities etc. For Private Circulation Only 22 2. Invasion-It is the successful establishment of one or more species on a bare area through dispersal (by wind water birds etc.) or migration, followed by species or establishment. As growth and reproduction start, these pioneer species increase in number and form groups or aggregations. 3. Competition and coactions- As the number of individuals grows there is interspecific (between species) and intraspecific (within species) competition for space water and nutrition. This influence on each other in a number of ways is called coaction. 4. Reaction- the cause of ecosystem change, is the impact that established species have upon their own environments, sometimes subtle and sometimes overt alteration of one's own environment. This modification of the environment by established species is called reaction and the modifications are very often such that they become unsuitable for the existing species and favour some new species which replace them. This reaction is what leads to seral communities. 5. Stabilization-The succession ultimately culminates in a more or less stable community called climax which is in equilibrium with the environment owing to full adjustment with the environment, maximum biomass and mutually beneficially linkages with other organisms Significance of Biotic succession The information gained through the understanding that the sequence of seral communities in succession is fixed is very useful. For ecologists it helps in their study of any area, in recognizing the seral stage at any area and to understand its stage of succession. It also helps them judge the history of an area whether it was a lake or rock or desert in the past. In measures of afforestation and reforestation, this understanding helps in incorporating the conditions and procedure that is conducive to bringing about a climax community of forests. Commercially it helps in maintaining a particular biotic community by interfering with biotic succession by identifying and preventing the members of the next seral stage to invade the area. Natural Control Have you thought about the various implications of the fact that in a forest all the plants and animals are present in relation to the dominant species? For example in a typical rain forest an almost solid roof is formed by the tops of large trees. The dense mass of leaf material makes a permanent ceiling for the entire forest (since the trees are not deciduous). This prevents direct sunlight from reaching the ground, which means that there is little undergrowth. It is obvious that because of the dominant tree canopy through out the year, only shade loving plants flourish except in pockets where a tree has fallen and sunlight enters in till the space is filled up again. It is also obvious that according to the dominant flora of a habitat are the fauna that survive in these habitats (animals etc dependent on the plants prevalent in a habitat).So the climax condition in any habitat is very much in accordance with the dominant species which is currently mankind and mostly according to mankind is whatever other life survives and whatever does not... In this respect therefore our dominance of nature does not seem to have been against the natural growth and climax in natural habitats! So it is only natural that there also has to be a check not far off in future that is predestined for a species like ours. Aren’t we the dominant species altering our habitat making it unsuitable for our own survival which is what does happen naturally in succession in habitats which eliminates that errant species? Nature has never been helpless; it always has a check for everything, however slow in coming. Our efforts to conserve environment and remedy the damage is our effort to prevent the natural To understand Succession it would be interesting to study two types of succession, depending upon the nature of the habitat; namely Hydrosere and Xerosere. It is to be noted that the climax community irrespective of For Private Circulation Only 23 whether succession started from water body or desert or rock, is still a forest, implying that forest is the most diverse and hence most stable community. Hydrosere: Hydrosere or Hydrarch succession occurs in a pond and its community are converted into a land community in the following stages- Phytoplankton- rooted submerged stage -rooted floating vegetation(swampy)- reed swamp stage(marshy) –sedge meadow stage- Land plants Characteristics of Hydrosere:  Phytoplankton stage- In the initial stage, phytoplankton (cyanobacteria), green algae (Spirogyra, Oedogonium), diatoms etc are the pioneer colonizers.  Rooted submerged stage- The phytoplanktons consumed by zooplankton (protozoans as Amoeba, Euglena, Paramecium etc), fish such as sun fish, blue gill fish etc. Gradually these organisms die and increase the content of dead organic matter in the pond. This is then utilized by bacteria and fungi, and minerals are released after decomposition. Nutrient rich mud supports rooted hydrophytes which have roots but are submerged such as Hydrilla, Ceratophyllum etc in the shallow water zone which is created by increasing silt brought in by streams of water flowing into the lake. This submerged stage is also inhabited by animals such as may flies, dragon flies etc. and Crustaceans as Daphnia, Cyclops etc.  Rooted floating stage- The hydrophytes die and are decomposed by micro organisms and thus release nutrients. Due to silting, depth of water is further reduced, and sunlight is able to penetrate to the bottom. At the margin of pond grow rooted floating vegetation. Example- Nelumbo nucifera, Monochoria, Trapa etc.In floating stage faunal living space is increased and diversified. Example- frogs, salamander, hydra, diving beetles etc inhabit such conditions. Some turtles and snake also invade the pond.  Reed swamp stage- Gradually, the depth of water decreases due to water evaporation and organic matter decomposition. Free floating plants as Lemna, Azolla, Pistia, Spirodella, Wolffia etc increase in number as the availability of nutrients are more in water. When these die, they build up the pond ecosystem, resulting in further build up of the substratum. Pond becomes a Swampy ecosystem where the shoots of the plants are above water. The reed swamp species are Scirpus, Typha etc  Sedge meadow stage- With further increase in sedimentation the mud becomes almost visible with just a thin layer of water over it finally forming a marsh land. Mesic (growing in moderate moisture) communities like sedges like Juncus and grasses begin forming a mat like vegetation.  Wood Land Stage- The marshes get dry due to the sunlight and the marshy vegetation disappears. The soil encourages land plants as shrubs and trees.  Forest stage- Depending upon the geographic conditions, different forests like deciduous or tropical forest stage takes over. The once aquatic fauna gets replaced by land animals. Xerosere: Xerosere or Xerarch succession begins on exposed parent rocks (lithosere) or dry sand (psammosere). A lithosere involves following stages- crustose lichen stage (pioneers) – foliose lichen stage – moss stage – herbs stage – shrub stage – forest stage (climax stage). Characteristics of Lithosere:  Crustose lichen stage- The pioneer plants are lichens, later followed by stages of mosses and Selaginella (Spikemossess) that basically help in soil formation. Rocks cannot absorb water and are not in a position to hold nutrients, but the weak acids formed by the pioneer lichens to appear, the crustose lichens like graphis, Rhizocarpum etc corrode the rock surface forming small depressions and release the minerals needed for the growth of these lichens. For Private Circulation Only 24   Foliose lichen stage- The dead and decaying organic matter of the lichens along with the weathered rock and sand particles brought by the wind get collected in depressions making the substratum suitable for the growth of foliose lichens like Parmelia, which gradually replace the crustose lichens. These increase the shading of the rocks, accumulation of organic matter and formation of larger depressions thus accelerating soil formation. Lithosere also involves successive changes in animal life. Pioneer stages in animals are few species of mites, spiders and ants, which are exposed to harsh temperatures.  Moss stage- Large sized xerophytic mosses like Grimmia, Tortula shade the Lichens and replace them. Their rhizoids can penetrate deep into the crevices of the rocks, and more of soil and organic matter is added to the soil. During moss stage, many new species of mites, spiders, springtails invade the community.  Herbs stage- The compact mat formed by mosses retains sufficient moisture and especially in rainy season making it possible for seeds of annual grasses and herbs like Poa, Eleucine etc to germinate. The roots of these annuals and herbaceous vegetation penetrate deeper through the soil and cause more weathering of the rocks. Increased moisture and soil invites perennial grasses like Cymbopogon etc which spread very fast because of runners and rhizomes. Increased shade, soil moisture and perennial grasses makes the area suitable for the existence of several small animals. Herb stage is invaded by nematodes, mites and various insect larvae  Shrub stage- Xerophytic shrubs like Zizyphus, Rubus etc start invading the area and they soon replace the grasses. Shrubs provide more shade for the sol surface, and the atmosphere becomes more moist due to more of transpiration. Roots of shrubs cause more fragmentation of rocks and there is more accumulation of soil.  Forest stage: - Shrubs are replaced by hardy trees and the community becomes more stable, called the climax community. The nature of the climax community is determined by the climate of the area. For example in tropical regions the climax community may be a rain forest while in temperate regions it might be a coniferous or deciduous forest. Whereas areas with less rainfall will have grasses as climax community Great modifications occur in the fauna of shrub and forest stage. Numerous kinds of animals as snails, wire worm, millipede, mites, ants and amphibians such as frogs, salamander occur. Reptiles which occur there are skinks, turtles and other lizards. Birds such as goose, flycatcher and mammals as shrews, mouse, mole, squirrels, fox and chipmunk occur. Thus, the reason why climax community acquires stability is that a variety of producers, consumers and decomposers are present and the community can regulate the flow of energy and matter economically. Self-Assessment Questions 1. What are the three ways to summarize the structure of an ecosystem? 2. What are the functions of ecosystem? 3. The modifications of the environment by established or dominant species in a way that it is often detrimental to its own survival is called…………………………… 2.5 Major Types of Ecosystem Forest Ecosystems These ecosystems tend to be stable climax community of various strata of trees shrubs herbs climbers and a variety of animals and birds, or they are always moving towards maturity called a climax forest. This maturing, also called forest succession, of the ecosystem increases diversity. Management of forests for sustainability is desirable when forest diversity is threatened by overuse, resource exploitation and poor management. Forest ecosystems can be disrupted and harmed when not properly sustained. A sustained forest that is certified by a qualified certification program is assurance that the forest is managed to have maximum diversity while For Private Circulation Only 25 satisfying environmental and economic demands. Complex forest ecosystems are extremely diverse, ranging from dry desert shrub land to large temperate rain forests Depending on climatic conditions forests can be of various types a. Tropical Rain Forests- These are considered the storehouse of biodiversity and found near the equator having high temperature, humidity and rainfall favouring broad leafed evergreen tree growth which forms a dense canopy which prevents sunlight from reaching in. Therefore mostly shade loving smaller trees and shrubs exist as understory. Some trees shoot out through the canopy and stand out tall and are called emergent. On the tree trunks some woody climbers are found to grow which are known as Lianus. Epiphytes like orchids attach to the branches of big trees and their special leaves capture and hold the water falling from above. Large epiphytes often act like mini ponds in the forest crown and attract birds and animals like monkeys to make their home in the forest crown. Termites, mushroom and fungi grown on the ground layer which receives almost no sunlight. Warm temperature and moisture facilitate decomposition of dropped leaves releasing nutrients rapidly which the trees take up by the mycorrhizal roots. The silent valley in Kerala is the only tropical rainforest lying in India. Other examples are most notably the Amazon rainforest in South America, Central American countries such as Panama, the Kilum- Ijim Forest (west Africa) and Madagascar Lowland forest in Africa b. Tropical Deciduous Forests-Found a little away from equator, having warm climate, rainfall only during monsoon,(moderate amount of precipitation), ), a large part of year remaining dry and so favouring deciduous trees which lose their leaves in autumn. c. Tropical Scrub Forests- Found in areas where the dry season is very long favouring small deciduous trees and shrubs. Some areas of Western Ghats in India have shrub forests. d. Temperate Rain Forests- Found in temperate areas with adequate rainfall dominated by coniferous trees like pines, firs, redwood and also some evergreen broad leaved trees owing to the plentiful rainfall. Found in United States along the coastline of the Pacific Northwest and in Canada, and Alaska. Temperate rainforests are formed in the Pacific Northwest because the coastal mountain ranges in Washington, Oregon, and Northern California trap the air masses full of moisture that rise from the Pacific Ocean. As this moisture condenses into rain it creates lush rainforests with trees like the Coastal Redwood in California that grow to enormous sizes and a biomass that exceeds that of the tropical rainforests. e. Temperate Deciduous Forests- Found in areas with marked seasonality but moderate temperature and abundant rainfall throughout the year favouring broad leaf deciduous trees like oak(Quercus), hickory, poplar etc. Therefore they are more precisely termed as temperate broadleaf forest, and are found in North America, southern South America, Europe, and Asia. f. Evergreen Coniferous Forests(Boreal Forests)- Found south of arctic tundra having long cold and dry winters, sunlight being available for a few hours only and summer season being mild and short favouring coniferous trees like fir, cedar, pines, spruce etc. having tiny needle shaped leaves with wax coating to withstand the cold. The soil gets frozen in winter where only few species can survive. Species diversity is rather low in these forests. The taiga or boreal forest exists as a nearly continuous belt of coniferous trees across North America and Eurasia. Taiga is the Russian name for this forest which covers so much of that country Grassland Ecosystem Grasslands are open areas where grasses or grass-like plants are the dominant vegetation and where there are few trees. Grasses came to dominate over other species, such as trees, because they are better able to thrive in hot, dry climates where spring and summer rain is sparse. Grasses take advantage of moisture in the soil during spring and have many long, fine roots to search for water at, and just below, the surface of the soil. The blades of grass plants curve inward to capture rain drops and direct them into the center of the plant, where they are absorbed by the roots. A layer of mulch and a crust of mosses, lichens, liverworts and other organisms on the ground between the grasses help to shade the ground from summer heat and from wind, thus preventing For Private Circulation Only 26 evaporation of precious water from the root zone below. Grass pollen is distributed by the wind that blows constantly in these dry, open areas. Grass seeds themselves are tiny cylinders, often with a long thread-like "awn" on the end, allowing them to move into cracks in the ground towards moisture. Grasses are also able to withstand grazing and fire. The growing point of most plants is situated at the tip of a leaf or shoot, but in grasses it is at the base, close to the ground. When a grass plant has been grazed or burned it is able to grow again from this protected base. Grasses are not the only plants in grasslands. The rolling landscape of grasslands includes hills, river valleys, canyons and cliffs. All these features alter the amount of sun and precipitation a specific part of the landscape receives. Elevation also influences temperature and precipitation: at higher elevations days are cooler and shorter, precipitation is higher and snow stays longer. Some areas of the grasslands are hot and dry while others may be relatively cool and moist. Flowering plants become more abundant with elevation. Many flowering plants, also called forbs, have adapted to the hot, dry climate, completing their cycle of flowering, seed formation and drying out before the hottest part of the summer. Shrubs are also an important component of grasslands, and in some areas they are the dominant plants which have long, deep tap roots that search for water well below the surface. Water runs over the landscape in the form of rivers, streams and small creeks, collecting in low areas to form lakes, ponds, wetlands and moist ground. The combination of landscape features, elevation and climatic differences create a mosaic of plant communities and habitats that includes open grasslands; rocky talus slopes and rock outcrops; riparian areas; wetlands; ponds and lakes; gullies; aspen stands; open coniferous forests; and closed coniferous patches, shoal forests. Distinct plant and animal species live in grasslands; they are adapted to living where drought is common, summers are long and hot, and winters are cold and relatively dry. Many animals that live in grasslands are grazers, like the California Bighorn Sheep, and many, like the marmot, burrow underground. Some animals, such as the Sharp-tailed Grouse, use both the grasslands and nearby forests during the year, while others such as the Western Harvest Mouse (vole) spend their whole lives in the grasslands. Three types of grasslands are found to occur in different climatic regions a. Tropical Grasslands-In Africa these are known as Savannas, which have tall grasses, scattered shrubs, stunted trees and perennating bulbs, rhizomes, runners etc. Termite mounds are very common. Animal diversity is high including Zebras, giraffes, gazelle, antelope b. Temperate Grasslands-In United States and Canada these grasslands are known as prairies, in South America as Pampas, in Africa as Velds and in central Europe and Asia they are known as Steppes. The soils are very fertile and often cleared for agriculture. c. Polar Grasslands- These grasslands are found in Arctic Tundra where the climate is too cold and harsh for trees to grow. A thick layer of ice remains frozen under the surface of soil throughout the year. Only in summers when the sun shine round the clock some annual plants grow and even shallow lakes, bogs etc appear which attract migratory birds. Animals include arctic wolf, weasel, arctic fox, reindeer etc. Desert Ecosystem Deserts are defined as regions wherein the average annual precipitation seldom exceeds more than 10 inches per year, and the amount of water lost to evapotranspiration is much more than the amount of water gained by precipitation. Deserts are basically of two types that is, hot and cold deserts. Hot deserts such as the Sahara in Africa (tropical desert) and Mojave in Southern California(temperate desert) and cold deserts, like Gobi desert in China and the best example being Antarctica. In India we have a hot desert, the Thar in Rajasthan. One of the prominent differences between the two types of desert is the form of precipitation, which is snowfall in cold deserts and rainfall in hot deserts. Irrespective of whether it is a hot or a cold desert, the characteristic traits of For Private Circulation Only 27 both almost remain the same. In fact the areas which we refer to as hot deserts have a chilling temperature at night. Though a desert may seem like a barren land devoid of forms of life, life does exist in this harsh environment. Numerous plants and animal species have adapted to these seemingly unsuitable conditions. In the desert ecosystem, climate is a deciding factor for the existence of forms of life. In deserts, temperatures can reach up to 115° F during the day, and come down to 32° F at night. Many plants and animals have adapted themselves over the years, and have become an important part of the desert ecosystem today. Desert Ecosystem: Animals Deserts are home to a number of species of the animal kingdom. Biodiversity of the deserts is as unique as other biomes of the world. Like in most of the other ecosystems, plants are the primary producers, while rodents, insects and reptiles which feed on these plants are the primary consumers. Then come the secondary consumers, who mainly comprise larger reptiles and insects which feed on primary consumers. At the top of the desert food chain are the apex predators in the form of birds and mammals. Most prominent members of the desert animals list include the Gila monster, chuckawallas, desert tortoise, rattlesnakes, hawks, ostriches, bobcat, kangaroo rats, mountain lions, etc. Most of these desert animals are nocturnal, i.e. active during the night, and spend the entire day burrowing. This adaptation helps them to fight the soaring temperatures that persist during the day. Water is scarce in deserts; these animals also have modified themselves to make the most of the available water. Some animals absorb water from plants, while others store it in their fatty tissues like the hump of the Camel. Desert Ecosystem: Plants Desert vegetation is only thought about as cactus. However, within cactus, there are different types which grow in different deserts of the world. These plants have modified themselves to sustain in the desert environment. Some plants store water in the specialized tissues, while others have small leaves with hair like structures which reduce the evaporation of moisture. In many cactus stem gets flattened and develop chlorophyll and take up the function of photosynthesis whereas leaves become like thorns to prevent evapotranspiration losses. In North American deserts, barrel cactus is the most abundantly found cacti species, while other species include crimson hedgehog cactus, pancake prickly pear cactus, saguaro cactus, etc. Other cactus plants such as brittle bush, saltbush, creosote bush, desert ironwood, gravillias, Joshua tree, Mojave aster, Soaptree yucca, hanging chain cholla, etc., are also quite common in deserts. Aquatic Ecosystems Aquatic systems are those that contain plants and animals that predominantly depend on a significant amount of water to be present for at least part of the year. They are either freshwater or marine. Freshwater ecosystems are further standing type (lentic) like ponds or free flowing type(lotic) like rivers. Pond Ecosystem- Ponds are often shallow water bodies and seasonal. Like in a forest, the top, middle, and bottom of a pond can be vastly different from each other, and even the layers in between. Under different temperature or light conditions the water in a pond can vary greatly in oxygen, clarity, and other factors that effect where plants and animals might live. The air above the pond and the land below the pond are important as well, as those provide space for animals to live, plants to root, and predators and prey to interact. Diversity - A pond is not just a small lake with frogs and fishes, rather there are thousands of different species of plants, algae, insects fishes and animals living together in a natural pond. The more diverse a pond is (more species that it has) the stronger and healthier it is. For Private Circulation Only 28 Micro-organisms - Some of the most important plants and animals in a pond are micro organisms and while a few may cause disease, almost all are very beneficial and important to a pond ecosystem. While bigger animals may fly, walk, or swim away to other ponds, micro-organisms are always present in large numbers. Macro-organisms - Larger plants and animals that are easy to see on a pond are called "macro-organisms (macro=large). They are the plants and animals that we often notice first, and can more easily spread from pond to pond, for example water birds. Lake Ecosystem- These are usually big water bodies having shallow water zone called littoral zone, open water zone where effective penetration of sunlight takes place called limnetic zone and a deep bottom area where light penetration is negligible called profundal zone. Organisms- Several types of organisms occur like planktons (that float on water surface), nektons (that swim like fishes), Neustons (rest ir swim on surface, like water insects, Benthos (attached to bottom like snails), Periphytons(clinging to other plants and surfaces like crustacians) Dal lake of Srinagar, Naini lake of Nainital , Loktak lake in Manipur are some famous lakes of the country. Streams and Rivers- Streams are shallow flowing water and rivers are large streams flowing through plains and falling into the sea. Stream organisms have to face extremes of temperature and current but constant movement and shallow water provides abundant oxygen. Large rivers are relatively deep and wide and rich in organic matter but also contain a lot of inorganic sediment produced by erosion and runoff into the upland waters. Thus, the water is more turbid (muddy), and there is insufficient light to support as much photosynthesis as in smaller rivers. Collectors and predators dominate the consumer community, and consumption exceeds primary production. Fish species such as sturgeon and catfish, which feed on sediments, are more common here than predatory fish. All lotic organisms must adapt to drift, the incessant flow of water towards the sea, carrying nutrients and the organisms themselves downstream. Drift is particularly significant when spring snow melts and heavy summer rains increase the current. River valleys offer especially rich farmland because of the great quantities of nutrients deposited by periodic flooding. Nutrient loss by drift is compensated for by the continual addition of riparian organic matter to the lower-order upland streams, while animals compensate for drift by their rheotaxis and other means. Many aquatic insects fly upstream to lay their eggs, and fish such as trout and salmon are well known for their upstream spawning runs. The immature animals drift downstream as they grow and typically reach maturity at lower altitudes, only to repeat the process and deposit their offspring back in the headwaters. Marine ecosystems-These are among the largest of Earth's aquatic ecosystems. They include oceans, salt marsh and estuaries and lagoons, mangroves and coral reefs, the deep sea and the sea floor. Marine waters cover two- thirds of the surface of the Earth. Such places are considered ecosystems because the plant life supports the animal life and vice-versa. Marine ecosystems are very important for the overall health of both marine and terrestrial environments. According to the World Resource Center, coastal habitats alone account for approximately 1/3 of all marine biological productivity, and estuarine ecosystems (i.e., salt marshes, seagrasses, mangrove forests) are among the most productive regions on the planet. In addition, other marine ecosystems such as coral reefs, provide food and shelter to the highest levels of marine diversity An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and ocean environments and are subject to both marine influences, such as tides, waves, and the influx of saline water; and riverine influences, such as flows of fresh water and sediment. The inflow of both seawater and freshwater provide high levels of nutrients in both the water column and sediment, making estuaries among the most productive natural habitats in the world. For Private Circulation Only 29 Estuary mudflats seem an unlikely setting for some of the most productive habitats in the world, but here at the interface of land and sea life abounds though for the select few. Certain plants, seaweeds and photosynthetic micro-organisms (phytoplankton) absorb nutrients at a fast rate, grow rapidly and produce lots of food. The estuary is a hostile environment for most plants because salt dominates. A few grow further back on the shore, where they live in a fluctuating environment of sea water and fresh water. These plants must cope with:  varying salinity levels  strong currents and storm waves  varying exposure to sunlight and wind  low oxygen levels in muddy soils. Estuaries are termed ‘open’ ecosystems because they are vitally linked to the wider environment. Nutrients are carried in from the land via rivers, and from the sea by the tides. Some of these nutrients are then taken out again when animals such as fish and birds leave the estuary. Some are also flushed out to sea on outgoing tides. Living organisms within an estuary co-exist in a network of interdependent feeding relationships that is food web. Estuaries have a rich biodiversity and many of the species are endemic. An estuarine food web contains the following elements:  Phytoplankton. These microscopic organisms manufacture food by photosynthesis and absorb nutrients such as phosphorus and nitrogen from the water.  Detritus (dead organic matter).  Microscopic animals known as zooplankton eat some of the phytoplankton. The remainder of the phytoplankton becomes detritus, when it dies.  Larger estuary animals such as filter-feeding worms, shellfish and hungry young fish feed on the zooplankton and detritus. There are many migratory species of fishes like eels and salmons in which half of the life is spent in fresh water and half in salty water. Some fishes migrate to fresh waters in the breeding season. 2.6 Summary > Ecosystems are complex and varied but they have a basic structure and functions. > There is an amazing complexity to different ecosystems. > Ecosystems are not stable and succession is a feature of ecosystems, that is structural changes take place over time till stable communities are established over time 2.7 Terminal Questions Multiple Choice Questions 1. The study of interactions between living organisms and man is called as A. Ecosystem B. Ecology C. Phytogeography D. Phytoecology 2. The two components of the ecosystem are A. plants and animals B. plants and light C. abiotic and biotic D. weeds and micro-organisms 3. The largest unit of living organisms on Earth is A. Ecosystem B. Atmosphere C. Biome D. Biosphere 4. Most stable ecosystem is A. Forest B. Desert C. Ocean D. Grassland 5. Usable energy is lost at each level of a food chain in the form of A. heat B. chemical energy C. light D. mechanical energy For Private Circulation Only 30 2.8 Answers Self-Assessment Questions 1. Trophic levels, Trophic relationships, Ecological pyramids 2. Energy flow and Nutrient cycling 3. Reaction Terminal Questions Multiple Choice Questions 1.A 2.C 3. D 4.C 5. A References http://en.wikipedia.org/wiki/Ecosystem http://schools.utah.gov/curr/Science/sciber00/8th/energy/acrobat/ecosys.pdf http://www.psu.edu/dept/nkbiology/naturetrail/succession.htm http://forestry.about.com/od/environmentalissues/a/forest_ecosystem.htm http://www.bcgrasslands.org/whataregrasslands.htm http://www.buzzle.com/articles/desert-ecosystem.html http://www.sci.sdsu.edu/classes/bio100/Lectures/Lect22/lect22.html http://en.wikipedia.org/wiki/Marine_ecosystem http://en.wikipedia.org/wiki/Estuary http://quest.arc.nasa.gov/projects/jason/xv/docs/TempRain.pdf http://www.tutornext.com/energy-flow-models/11853 http://en.wikipedia.org/wiki/Food_web (file from the Wikimedia Commons) For Private Circulation Only 31  Module 3 NATURAL RESOURCES Structure Objectives 3.1 Introduction 3.2 Classification 3.3 Major Natural Resources 3.4 Summary 3.5 Questions 3.6 Answers Objectives At the end of the unit you will be able to: > understand natural resources and their importance > understand the issues that affect our resources and what we can do to sustain them. 3.1 Introduction There is a sufficiency in the world for man's need but not for man's greed. ~Mohandas K. Gandhi A substance in nature becomes a resource when it is being utilized. Thus, natural resources can be defined as those natural reserve stocks of supply, which man utilizes for his sustenance and welfare. The reservoirs of natural resources are- (1) the sun (2) the atmosphere (3) the lithosphere (4) the hydrosphere. Examples of natural resources provided by these reservoirs are air, water, soil, coal, minerals, coal, forests, crops, wildlife 3.2 Classification Classification of resources can be done in three major ways. 1. Exhaustible and Inexhaustible resources 2. Renewable and Nonrenewable resources 3. Biotic and Abiotic resources (Traditional Classification) Exhaustible Resources are those which are limited and can be diminished or degraded if improperly used. E.g. fossil fuels Inexhaustible Resources are those that will never run out (though air can be qualitatively affected by pollution and become limiting). E.g. Sunlight, air Renewable Resources are those that can be replaced in a timely manner, which include wild life, plants, trees, water, grass and wind energy. Non renewable resources may be irreplaceable once extracted from water or soil and include gold, silver, fossil fuels, diamonds, natural gas, copper and ore Biotic resources include all living things and their products e.g. forests and their products Abiotic resources include all non living resources such as minerals, fossil fuels and natural gas. For Private Circulation Only 32  Renewable : soil(Biotic +Abiotic) Wildlife(Biotic) Exhaustible Non renewable: minerals(Abiotic) Natural Resources Fossil fuels(Abiotic) Inexhaustible : sunlight, air/wind (Abiotic). Fig 3.1 Diagrammatical depiction of the classification of resources to understand how they are inter twined 3.3 Major Natural Resources It is very important to protect and conserve our natural resources and use them in a judicious manner so that we donot exhaust them. To be able to sustain resources we need to understand them and their problems. The major natural resources are:- 1. Forest resources 2. Water resources 3. Mineral resources 4. Food resources 5. Land resources 3.3.1. Forest resources A forest can be defined as a biotic community predominantly of trees, shrubs or any other woody vegetation usually with a closed canopy. Depending upon the type of dominant vegetation, the forest biomes can be classified into coniferous forest, tropical forest and temperate forest. There are two broad categories of functions that forests perform. The protective forests on hill slopes protect the soil and keep it in place; the productive forest produce timber and other forest produce like bamboo, cane and thatch. A third type of forest that is being included is the social forest. The growing magnitude of our need for wood, matched by the destruction of trees by our rapidly multiplying population has made it important to plant and maintain many small areas of forests for local needs. We should recognize the importance for forest conservation as the damage caused to environment when the original forest resources are destroyed cannot always be corrected. Afforestation and reforestation efforts should match the rate of exploitation of forests, which is more often not the case. Reforestation of hilly regions is of utmost importance as it helps flood prevention as tree roots hold the water and prevent excess run off. The soil of the Himalayan region is rich and deep and there is a chance of the new plantation in reforestation effort of growing quickly. But the case with Western Ghats is not the same, where the soil is thin and Laterite, held in place for centuries only by the tree roots. Once denuded, a slope on the Western Ghats cannot be replanted, for the thin soil is almost immediately washed away. These were protective forests but all over the country the ‘protective forests on the hillsides have either gone, or are in the process of going. If a forest loses 40% of its strength, it ceases to be efficacious, and can no longer protect the soil. Therefore it is important to understand For Private Circulation Only 33 that the mistakes we make in deforestation cannot always be remedied by reforestation. According to Laeeq Futehalli “To reduce our forest area in size or quality, is to deliberately impoverish our country, and ultimately, our earth. We must think of ourselves not only as beneficiaries but also as trustees of the wealth which comes to us through our forests.” Afforestation is the establishment of a forest or stand of trees in an area where the preceding vegetation or land use was not forest. Reforestation is the reestablishment of forest cover either naturally (by natural seeding, coppice, or root suckers) or artificially (by direct seeding or planting), usually maintaining a same or similar forest type, and done promptly after the previous stand or forest was removed. Destruction of whole blocks of forests takes place to make room for other activities like agriculture, hydro- electric projects or for resettling refugees. But a great deal of forests is destroyed by more indirect methods. While remaining a forest in name its character is drastically changed in a manner that it cannot fulfill its role. The issues that make a forest loose its character is in one word ‘exotics’. The invasion of imported (exotic) plants which do not rightfully belong in our country, once it captures the forest, it is virtually impossible to free it. An exotic plant is a plant which has evolved in another geographical area far away, but with a similar climate. By some chance- quite often human –a seed or plant finds its way into our areas-like our forests. Here its natural enemies are absent – that is, those animals, birds and insects, which feeds on it, and so the exotic spreads everywhere unhampered by pests and predators. Meanwhile it does not provide suitable food and shelter for the local animals for it could be strange tasting, unfamiliar, indigestible or even poisonous. Thus the exotic plants with no natural checks or enemies spread all through the forest, overwhelming the local vegetation. The reduction in quantity of the natural vegetation means a reduction in the food available for the forest animals, and this upsetting of the balance starts a chain reaction where the vegetation and animals both suffer, and the total quality of the forest is greatly diminished. 1. The eupatorium is an escapee from South America. It is a man high bushy shrub which first appeared in our forests around the 1960s. Being without enemies it began to spread rapidly. Apart from all the issues that are associated with the spread of exotic plants as mentioned above, eupatorium has another alarming characteristic; it is prone to catch fire during the dry months. The eupatorium is such a disaster to our forests in every way that unless we interfere we might find that our fine forests have become eupatorium deserts. 2. Another exotic problem but of a different kind is the eucalyptus which is native of Australia. Since it is very fast growing and therefore useful for producing, quick timber, especially for pulp and paper making, it was planted extensively in India, especially in the south. It only grows where it is planted but its great drawback is that its roots draw up a tremendous amount of moisture from the ground, so that a large stand of eucalyptus trees can reduce the water table of an entire area. It gives little food or shelter to any native bird or animal, and except for one or two special varieties, the native vegetation does not grow in its shade. In other words, the eucalyptus does not integrate with the local flora or fauna and a eucalyptus plantation remains a sterile commercial plantation. It never becomes a part of a forest and so it must not be mixed up with the forest proper and should rather be treated as a crop. For Private Circulation Only 34  The Kolar district of Karnataka is one of the leaders in Social Forestry with World Bank Aid, but all its 11 taluks suffer from drought. It is because the tree used for plantation here was Eucalyptus which later came to be known to lower the water table because of its high transpiration rate. This case speaks for the amount of damage we do to our own region by our lack of understanding of the infinite aspects of nature. Activities with least interference to natural processes or replicating what existed naturally in an area(planting indigenous trees) is the best option keeping in view that only Uses of Forests 1. Commercial uses like timber, firewood, pulpwood, food items, gum, resins, non-edible oils, rubber, fibers, lac, bamboo canes, fodder, medicine, drugs etc. 2. Ecological services include production of oxygen, reduction of global warming by absorbing CO2, habitat for wild animals, regulation of hydrological cycle by absorbing water into soil and recharging springs, soil conservation, improving air quality. 3. Proximity to forest area has uses like, reduction in heat due to transpiration from the large mass of leaves in a forest. Thus they help to moderate climate. The reduction in the number of forests and trees near towns like Ranchi and Pune have made the towns more scorching, forests near farmlands break the force of wind, provides stillness and so protects the agricultural land from losing the fertile top soil, pest population is also controlled as the forest provides the natural enemies for the pests Causes of deforestation 1. Increasing population and livestock resulting in increased requirement of timber, fuel wood, land for grazing, for farms, for habitation etc 2. Industrialization, paper industries, plywood industries based on forest produce, clearing areas for setting up industries without considerations or assessments, all cause gradual decline of forests. For example the finest areas of the great sal belt of north India (Bihar) were sacrificed to build the industrial township of Rourkela, Durgapur and Bhilai. This case depicts how decisions favouring short term benefits leads to long- term loss. As with the forest gone the climate of the locality became unbearably hot and Bihar became a prey to alternating floods and drought, even the local populace was found to be unable to adapt to work in factories removed from their usual way of living on forest produce. 3. Activities like mining and quarrying are also responsible for large scale deforestation. 4. Big dams and river valley projects are also responsible for the destruction vast areas of forests 5. Other factors in the past have been shifting cultivation, allotting forest land to refugees to accommodate the waves of refugees over the last 25 years from Tibet, Burma, Sri Lanka, East Africa and Pakistan Hazards of Deforestation 1. Soil Erosion, increase of floods, heavy siltation of dams due to soil lost from deforested hills 2. Depletion of resources like timber , firewood etc For Private Circulation Only 35  3. Changes in the microclimate 4. Destruction of wildlife as the forest habitat is lost and depletion of biodiversity in terms of both flora and fauna. 5. Desertification of formerly fertile lands, leading to loss of precious land 6. Destruction of the scenic beauty of the environment Forest Conservation measures In 1953 Indian government drew up a National Forest Policy whose main directive was that 33% of the land surface must remain under forest, but less than 50 years later, we find that the area of forest has been reduced to about 11% of the land surface The central and State Government has launched several afforestation programmes throughout the country as a part of the forest conservation policy. 1. The Social Forestry Programme was launched in 1976 which seeks to use public as well as waste land to grow firewood, fodder and small timber to meet the daily requirements of the rural people 2. Another afforestation measure is the Urban Forestry Programme. Have you noticed the trees in your city? What sort are the trees throughout the length of the roadsides, are they impressive looking (ornamental), shady or fruit trees? Urban forestry programme involves planting of trees for aesthetic purposes in urban areas, fruit trees and flower trees are also planted along roadsides and also in the private compounds. Ornamental trees are planted in vacant land and parks in the urban areas. These plants reduce air pollution and also increase the scenic beauty of the area. 3. Agroforestry Programme encourages the use of a single block of land for farming, forestry and animal husbandry. The forest area enriches and protects the agricultural area and the crops. The grass in the shade of trees especially during the hot months is more nutritious for cattle and grazing to a limited extent also does no major harm to a forest. What can the common people do to help with forest conservation? There are several movements started by people, for example the Chipko Movement in Tehri Garhwal area of UP was initiated by Shree Sundar Lal Bahuguna in1973 in which women hugged the trees and successfully checked felling of trees by contractors. The public agitation against the construction of a hydroelectric project in Silent Valley saved a kind of forest now rare in India, evolved over thousands of years, from being lost under water and this happened as a result of public awareness towards the comparative need and importance of preservation of nature with respect to short term benefits of hydroelectric projects. Government drives cannot succeed without the support of local populace. As far as Social forestry is concerned a lesson can be learnt from Gujarat state, where every small piece of open land is used to plant trees for fruit, fuel, wood and shade. People have to cooperate in supporting and protecting the saplings. Self-Assessment Question 1. Though Bangalore has a larger number of trees as compared to other Indian cities, why according to you is it that the bird life is not so rich? How do you think it impacts the agriculture? For Private Circulation Only 36 3.3.2 Water Resources Water resources are sources of water that are useful or potentially useful to humans. Uses of water include agricultural, industrial, constructions, household, recreational and environmental activities. Virtually all of these human uses require fresh water. 97% of water on the Earth is salt water, and only 3% is fresh water of which slightly over two thirds is frozen in glaciers and polar ice caps. The remaining unfrozen freshwater is mainly found as groundwater, with only a small fraction present above ground or in the air. Fresh water is a renewable resource, yet the world's supply of clean, fresh water is steadily decreasing. Water demand already exceeds supply in many parts of the world and as the world population continues to rise, so too does the water demand. With the growth of human population, there is an increasing need for larger amounts of water to fulfill a variety of basic needs. Today, in many areas, this requirement cannot be met. The over-utilization of water occurs at various levels.Most people use more water than they really need. Most of us waste water during a bath