BCH 101 Environmental Science - Arunodaya University PDF

B.Com (HONOURS) BCH 101 - Environmental Science 1st Semester Arunodaya University - School of Arts, Humanities and Social Science 1 Arunodaya University - School of Arts, Humanities and Social Science 2 Index Unit No. Topic Page No. Unit 1 Introduction to environmental studies 7 Unit 2 Ecosystems 17 Unit 3 Natural Resources: Renewable and Non‐ 39 renewable Resources Unit 4 Biodiversity and Conservation 62 Unit 5 Environmental Pollution 86 Unit 6 Environmental Policies & Practices 110 Unit 7 Human Communities and the Environment 142 Unit 8 Field work 167 Arunodaya University - School of Arts, Humanities and Social Science 3 Syllabus Unit 1: Introduction to environmental studies (2 Lectures) ▪ Multidisciplinary nature of environmental studies; ▪ Scope and importance; Concept of sustainability and sustainable development. Unit 2: Ecosystems (6 Lectures) ▪ 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) Unit 3: Natural Resources: Renewable and Non-‐‐renewable Resources (8 Lectures) ▪ 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 over-exploitation of surface and ground water, floods, droughts, conflicts over water (international & inter- state). ▪ Energy resources : Renewable and non renewable energy sources, use of alternate energy sources, growing energy needs, case studies. Unit 4: Biodiversity and Conservation (8 Lectures) ▪ 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 invasions; Conservation of biodiversity : In- situ and Ex-situ conservation of biodiversity. ▪ Ecosystem and biodiversity services: Ecological, economic, social, ethical, aesthetic and Informational value. Unit 5: Environmental Pollution (8 Lectures) ▪ Environmental pollution : types, causes, effects and controls; Air, water, soil and noise pollution Arunodaya University - School of Arts, Humanities and Social Science 4 ▪ Nuclear hazards and human health risks ▪ Solid waste management : Control measures of urban and industrial waste. ▪ Pollution case studies. Unit 6: Environmental Policies & Practices (7 Lectures) ▪ 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. Unit 7: Human Communities and the Environment (6 Lectures) ▪ 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). Unit 8: Field work (Equal to 5 Lectures) ▪ 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. Suggested Readings: Carson, R. 2002. Silent Spring. Houghton Mifflin Harcourt Gadgil, M., & Guha, R. 1993. This Fissured Land: An Ecological History of India. Univ. of California Press. Gleeson, B. and Low, N. (eds.) 1999. Global Ethics and Environment, London, Routledge. Arunodaya University - School of Arts, Humanities and Social Science 5 Gleick, P. H. 1993. Water in Crisis. Pacific Institute for Studies in Dev., Environment & Security. Stockholm Env. Institute, Oxford Univ. Press. Groom, Martha J., Gary K. Meffe, and Carl Ronald Carroll. Principles of Conservation Biology. Sunderland: Sinauer Associates, 2006. Grumbine, R. Edward, and Pandit, M.K. 2013. Threats from India’s Himalaya dams. Science, 339: 36-- 37. McCully, P. 1996. Rivers no more: the environmental effects of dams (pp. 29--64). Zed Books. McNeill, John R. 2000. Something New Under the Sun: An Environmental History of the Twentieth Century. Odum, E.P., Odum, H.T. & Andrews, J. 1971. Fundamentals of Ecology. Philadelphia: Saunders. Pepper, I.L., Gerba, C.P. & Brusseau, M.L. 2011. Environmental and Pollution Science. Academic Press. Rao, M.N. & Datta, A.K. 1987. Waste Water Treatment. Oxford and IBH Publishing Co. Pvt. Ltd. Raven, P.H., Hassenzahl, D.M. & Berg, L.R. 2012. Environment. 8th edition. John Wiley & Sons. Rosencranz, A., Divan, S., & Noble, M. L. 2001. Environmental law and policy in India. Tripathi 1992. Sengupta, R. 2003. Ecology and economics: An approach to sustainable development. OUP. Singh, J.S., Singh, S.P. and Gupta, S.R. 2014. Ecology, Environmental Science and Conservation. S. Chand Publishing, New Delhi. Sodhi, N.S., Gibson, L. & Raven, P.H. (eds). 2013. Conservation Biology: Voices from the Tropics. John Wiley & Sons. Thapar, V. 1998. Land of the Tiger: A Natural History of the Indian Subcontinent. Warren, C. E. 1971. Biology and Water Pollution Control. WB Saunders. Wilson, E. O. 2006. The Creation: An appeal to save life on earth. New York: Norton. World Commission on Environment and Development. 1987. Our Common Future. Oxford University Press. Arunodaya University - School of Arts, Humanities and Social Science 6 Unit 1: Introduction to environmental studies The importance of environmental science and environmental studies cannot be disputed. The need for sustainable development is a key to the future of mankind. Continuing problems of pollution, loss of forget, solid waste disposal, degradation of environment, issues like economic productivity and national security, Global warming, the depletion of ozone layer and loss of biodiversity have made everyone aware of environmental issues. The United Nations Coference on Environment and Development held in Rio de Janerio in 1992 and world Summit on Sustainable Development at Johannesburg in 2002 have drawn the attention of people around the globe to the deteriorating condition of our environment. It is clear that no citizen of the earth can afford to be ignorant of environment issues. Environmental management has captured the attention of health care managers. Managing environmental hazards has become very important. Human beings have been interested in ecology since the beginning of civilization. Even our ancient scriptures have emphasized about practices and values of environmental conservation. It is now even more critical than ever before for mankind as a whole to have a clear understanding of environmental concerns and to follow sustainable development practices. Multidisciplinary nature of environmental studies Environmental studies cover every aspect that affect a living organism, as it interacts with the surroundings in its quest to live. Environmental studies are integrative, but the core of the subject comprises biological sciences like zoology, botany, microbiology and physiology. Many environmental concerns can be resolved through application of biotechnology and molecular biology, while bioinformatics can serve as a database at molecular level. Environmental studies are therefore multidisciplinary and aims at unravelling the ways in which human beings and nature correlate, sustaining life and man’s unquenchable thirst for development with limited and finite resources. Arunodaya University - School of Arts, Humanities and Social Science 7 Physics, chemistry, biology, anthropology, geology, engineering, archaeology, sociology, economics, statistics, political science, law, anthropology, management, technology and health sciences are all its components. Among these physics, chemistry, geography, geology and atmospheric science help us understand the basic concepts of structural and functional organization, as well as the physical characteristics of our environment. Data simulation and interpretation needs the application of statistics and computer application, while mathematical science is often used in environmental modelling. The technical solutions for pollution management, waste management, green building and green energy can be found with expertise from the fields of engineering and architecture. e achievement of sustainability at all levels is interwoven with and dependant on international cooperation which in turn rests on international relations. Principles of sustainable development determine the drafts and negotiation of international accords and security issues. International cooperation is an indispensable factor in dealing with global environmental issues like climate change, transboundary pollution, trade in hazardous substances, ozone layer depletion, biodiversity loss, etc. Economics enables us to gain a better understanding of the social background needed to achieve growth and development. Keeping all these in mind, management studies will enable us to formulate policies, followed by legislation for their implementation. The study and treatment of environment is very much connected with philosophy, ethics and cultural traditions that help us achieve our goal sustainably. The air that we breathe, the water that sustains our lives, the food that gives us energy, the towns and the cities that we live in, in fact everything around us constitute the environment. It is the sum total of all life support systems. Therefore, it is essentially a multidisciplinary approach that brings about an appreciation of our natural world and human impacts on its integrity. It is an applied science as it seeks practical answers to making human civilization sustainable on the earth’s finite resources. Environment study deals with the analysis of the processes in water, air, land, soil and organisms which leads to pollute or degrade environment. It helps us for establishing standard, Arunodaya University - School of Arts, Humanities and Social Science 8 for safe, clean and healthy natural ecosystem. It also deals with important issues like safe and clean drinking water, hygienic living conditions and clean and fresh air, fertility of land, healthy food and development. Because, the environment is complex and actually made up of many different environments, including natural, constructed and cultural environments, environmental studies is the inter disciplinary examination of how biology, geology, politics policy studies, law, geology, religion engineering, chemistry and economics combine to inform the consideration of humanity’s effects on the natural world. This subject educates the students to appreciate the complexity of environmental issues and citizens and experts in many fields. By studying environmental science, students may develop a breadth of the interdisciplinary and methodological knowledge in the environmental fields that enables them to facilitate the definition and solution of environmental problems. Scope and importance Scope As we look around at the area in which we live, we see that our surroundings were originally a natural landscape such as a forest, a river, a mountain, a desert, or a combination of these elements. Most of us live in landscapes that have been heavily modified by human beings, in villages, towns or cities. But even those of us who live in cities get our food supply from surrounding villages and these, in turn, are dependent on natural landscapes such as forests, grasslands, rivers, seashores, for resources such as water for agriculture, fuelwood, fodder, and fish. Thus our daily lives are linked with our surroundings and inevitably affects them. We use water to drink and for other day-to-day activities. We breathe air, we use resources from which food is made and we depend on the community of living plants and animals which form a web of life, of which we are also a part. Everything around us forms our environment and our lives depend on keeping its vital systems as intact as possible. Our dependence on nature is so great that we cannot continue to live without protecting the earth’s environmental resources. Thus most traditions refer to our environment as ‘Mother Arunodaya University - School of Arts, Humanities and Social Science 9 Nature’ and most traditional societies have learned that respecting nature is vital for their livelihoods. This has led to many cultural practices that helped traditional societies protect and preserve their natural resources. Respect for nature and all living creatures is not new to India. All our traditions are based on these values. Emperor Ashoka’s edict proclaimed that all forms of life are important for our well being in Fourth Century BC. Over the past 200 years, however, modern societies began to believe that easy answers to the question of producing more resources could be provided by means of technological innovations. For example, though growing more food by using fertilizers and pesticides, developing better strains of domestic animals and crops, irrigating farmland through mega-dams and developing industry, led to rapid economic growth, the ill effects of this type of development, led to environmental degradation. The industrial development and intensive agriculture that provides the goods for our increasingly consumer-oriented society use up large amounts of natural resources such as water, minerals, petroleum products, wood, etc. Nonrenewable resources, such as minerals and oil are those which will be exhausted in the future if we continue to extract these without a thought for subsequent generations. Renewable resources, such as timber and water, are those which can be used but can be regenerated by natural processes such as regrowth or rainfall. But these too will be depleted if we continue to use them faster than nature can replace them. For example, if the removal of timber and firewood from a forest is faster than the regrowth and regeneration of trees, it cannot replenish the supply. And a loss of forest cover not only depletes the forest of its resources, such as timber and other non-wood products but affect our water resources because an intact natural forest acts like a sponge which holds water and releases it slowly. Deforestation leads to floods in the monsoon and dry rivers once the rains are over. Such multiple effects on the environment resulting from routine human activities must be appreciated by each one of us if it is to provide us with the resources we need in the long-term. Our natural resources can be compared with money in a bank. If we use it rapidly, the capital will be reduced to zero. On the other hand, if we use only the interest, it can sustain us over the longer term. This is called sustainable utilization or development. Arunodaya University - School of Arts, Humanities and Social Science 10 Importance The environment is not a single subject. It is an integration of several subjects that include both Science and Social Studies. To understand all the different aspects of our environment we need to understand biology, chemistry, physics, geography, resource management, economics and population issues. Thus the scope of environmental studies is extremely wide and covers some aspects of nearly every major discipline. We live in a world in which natural resources are limited. Water, air, soil, minerals, oil, the products we get from forests, grasslands, oceans and from agriculture and livestock, are all a part of our life support systems. Without them, life itself would be impossible. As we keep increasing in numbers and the quantity of resource improving this situation will only happen if each of us begins to take actions in our daily lives that will help preserve our environmental resources. We cannot expect Governments alone to manage the safeguarding of the environment, nor can we expect other people to prevent environmental damage. We need to do it ourselves. It is a responsibility that each of us must take on as one’s own. The productive value of nature: As scientists make new advances in fields such as biotechnology we begin to understand that the world’s species contain an incredible and uncountable number of complex chemicals. These are the raw materials that are used for developing new medicines and industrial products and are a storehouse from which to develop thousands of new products in the future. The flowering plants and insects that form the most species-rich groups of living organisms are thus vital for the future development of man. If we degrade their habitat these species will become extinct. If one sees being sold or used, a product that comes from an illegally killed wild species, if we do not inform the authorities, we become a party to its extinction. Once they are lost, man cannot bring them back. When we permit the destruction of a forest, wetland or other natural area and do not protest about it, future generations are being denied the use of these valuable resources and will blame us for these rash and negligent actions towards the environment. Thus the urgent need to protect all living species is a concept that we need to understand and act upon. While individually, we perhaps cannot directly prevent the extinction of a species, Arunodaya University - School of Arts, Humanities and Social Science 11 creating a strong public opinion to protect the National Parks and Wildlife Sanctuaries in which wild species live is an important aspect of sustainable living. There is a close link between agriculture and the forest, which illustrates its productive value. For crops to be successful, the flowers of fruit trees and vegetables must be pollinated by insects, bats and birds. Their life cycles however frequently require intact forests. Aesthetic/Recreational value of nature: The aesthetic and recreational values that nature possesses enlivens our existence on earth. This is created by developing National Parks and Wildlife Sanctuaries in relatively undisturbed areas. A true wilderness experience has not only recreational value but is an incredible learning experience. It brings about an understanding of the oneness of nature and the fact that we are entirely dependent upon the intricate functioning of ecosystems. The beauty of nature encompasses every aspect of the living and non-living part of our earth. One can appreciate the magnificence of a mountain, the power of the sea, the beauty of a forest, and the vast expanse of the desert. It is these natural vistas and their incredible diversity of plant and animal life that has led to the development of several philosophies of life. It has also inspired artists to develop visual arts and writers and poets to create their works that vitalize our lives. A wilderness experience has exceptional recreational value. This has been described as nature tourism, or wildlife tourism, and is also one aspect of adventure tourism. These recreational facilities not only provide a pleasurable experience but are intended to create a deep respect and love for nature. They are also key tools in educating people about the fragility of the environment and the need for sustainable lifestyles. In an urban setting, green spaces and gardens are vital to the psychological and physical health of city dwellers. It provides not only an aesthetic and visual appeal but the ability to ensure that each individual is able to access a certain amount of peace and tranquillity. Thus urban environmental planners must ensure that these facilities are created in growing urban complexes. Another important conservation education facility in urban settings includes the need to set up well designed and properly managed zoological parks and aquariums. These have Arunodaya University - School of Arts, Humanities and Social Science 12 go great value in sensitizing school students to wildlife. Many young people who frequented zoos as young children grow up to love wildlife and become conservationists. In the absence of access to a Protected Area, a botanical garden or a zoo, one concept that can be developed is to create small nature awareness areas with interpretation facilities at district and taluka levels. These areas can be developed to mimic natural ecosystems even though they could be relatively small in size. Such nature trails are invaluable assets for creating conservation education and awareness. They can be developed in a small woodlot, a patch of grassland, a pond ecosystem, or be situated in an undisturbed river or coastal area. This would bring home to the visitor the importance of protecting our dwindling wilderness areas. The option values of nature: While we utilise several goods and services of nature and enjoy its benefits, we must recognize that every activity that we do in our daily lives has an adverse impact on nature’s integrity. Thus if we use up all our resources, kill off and let species of plants and animals become extinct on earth, pollute our air and water, degrade land, and create enormous quantities of waste, we as a generation will leave nothing for future generations. Our present generation has developed its economies and lifestyles on unsustainable patterns of life. however, nature provides us with various options on how we utilize its goods and services. This is its option value. We can use up goods and services greedily and destroy its integrity and long- term values, or we can use its resources sustainably and reduce our impacts on the environment. The option value allows us to use its resources sustainably and preserve its goods and services for the future. Concept of sustainability and sustainable development Sustainability and sustainable development are extremely topical issues for modern society. The concept of sustainability was brought to the attention of humanity during the 20th century, when the increasing development of some countries originated environmental concerns and stimulated humans to gain a deeper understanding of natural resources, their dynamics and impact of overexploitation. The purpose of this essay is to introduce the concepts of sustainability and sustainable development and review their main implications. I will first describe how the capability of Earth Arunodaya University - School of Arts, Humanities and Social Science 13 and human systems to adapt to - and sustain - societal developments became a global concern. Then, I will provide a definition of sustainable development and I will finally discuss the main concerns for the future. To get a quick start, it may be useful to look at this video. You will get a first perception of what sustainability is, but the video will left you with many open questions, including: "and then? What should I do?". In order to better understand the importance of sustainability and its role for the progress of humanity it is useful to look back at when environmental preservation and restoration became relevant issues for humanity. Sustainability was first defined in ecology as the property of biological systems to remain diverse and productive indefinitely. Diversity is an essential requirement for a system to be flexible and able to adapt, which in turn is a necessary condition to survive to shocks. An example are healthy forests that proved to be able to survive for very long time in good conditions notwithstanding the impact of several environmental changes. Another example is the ocean. The concept of sustainability can be extended to any environmental, political and socio- economical system. Today, there is increasing evidence that environmental systems are strictly connected with human systems like political and economical ones, and therefore there is increasing awareness that sustainability of the whole earth system is linked with a two way interaction with human society. The extension of the concept of sustainability to societal development dates back to 1980s. At that time, it was a common belief that "societal development" - that is strictly related to engineering and economics - and "sustainability" - that is strictly related to environment and natural resources - were antithetic. Therefore, engineering and global economy were identified as the enemies of environmental protection and restoration. Development was identified as the main cause of environmental degradation, increased risk of natural hazards and disparity in the human systems. Political ideas and forces promoting progress and evolution of society were in different ways opposed or criticised by those promoting equality, diversity and environmental care within a democratic and participatory approach. Such a view led to political and scientific Arunodaya University - School of Arts, Humanities and Social Science 14 controversies, some of which are still debated today, which undermine the identification of real problems, priorities and ways forward. While, on the one hand, controversy may favor the confrontation of different opinions and therefore a comprehensive approach to a problem, on the other hand global economy and the environment are very complex systems and therefore their comprehension would benefit by a cooperative approach and a constructive debate. Actually, starting from the understanding that sustainability of contemporary society is strictly connected to societal development, the idea came forward to coin a new term and concept to emphasise that "sustainability" and "development" are not antithetic, bur rather strictly coupled. The 1980 World Conservation Strategy of the International Union for the Conservation of Nature was the first report that included a very brief chapter on a concept called "sustainable development". It focused on global structural changes and was not widely read. Sustainability is closely connected to resilience of the related systems. Resilience was first defined in ecology as the capacity of an ecosystem to absorb disturbance and still retain its basic structure and viability. In the context of sustainability of environment, economic and society, resilience implies the need to manage interactions between human-constructed systems and natural ecosystems in a sustainable way. Resilience-thinking addresses how much systems can withstand the human impact while still delivering, to the current and future generations, their needed services. The concept of sustainable development is subject to criticism, as on the one hand the whole Earth system, even in natural conditions, is not sustainable, as the history of other planets like Mars clearly shows. There is increasing evidence that Mars was once hosting water and maybe some forms of life, but the evolution of the planet caused the loss of water. On the other hand, human actions may help to achieve sustainability, through the management of the natural evolution of the Earth system. The human management of water resources, through the work of engineers, is a clear example where the human intervention may support the conservation of ecosystem and may shape the evolution of the landscape in a more sustainable manner. The concept of sustainability should be linked to the need of making the best possible use of Earth resources, including water, energy and food, with the awareness that future evolution and research innovation may be unpredictable, and the awareness that the processes governing the Arunodaya University - School of Arts, Humanities and Social Science 15 Earth system are affected by intrinsic uncertainty (think, for instance, at the impact that a planetary collision may have). Questions: 1. What is multidisciplinary nature of environmental studies? 2. What is scope and importance of environmental studies? 3. What is the concept of sustainable development? ************ Arunodaya University - School of Arts, Humanities and Social Science 16 Unit 2: Ecosystems What is an ecosystem? An ‘Ecosystem’ is a region with a specific and recognizable landscape form such as forest, grassland, desert, wetland or coastal area. The nature of the ecosystem is based on its geographical features such as hills, mountains, plains, rivers, lakes, coastal areas or islands. It is also controlled by climatic conditions such as the amount of sunlight, the temperature and the rainfall in the region. The geographical, climatic and soil characteristics form its non-living (abiotic) component. These features create conditions that support a community of plants and animals that evolution has produced to live in these specific conditions. The living part of the ecosystem is referred to as its biotic component. Ecosystems are divided into terrestrial or landbased ecosystems, and aquatic ecosystems in water. These form the two major habitat conditions for the Earth’s living organisms. All the living organisms in an area live in communities of plants and animals. They interact with their non-living environment, and with each other at different points in time for a large number of reasons. Life can exist only in a small proportion of the earth’s land, water and its atmosphere. At a global level the thin skin of the earth on the land, the sea and the air, forms the biosphere. At a sub-global level, this is divided into biogeographical realms, geographical realms, eg. Eurasia called the palaeartic realm; South and South-East Asia (of which India forms a major part) is the Oriental realm; North America is the Nearctic realm; South America forms the Neotropical realm; Africa the Ethiopian realm; and Australia the Australian realm. At a national or state level, this forms biogeo- biogeographic regions. graphic regions. There are several distinctive geographical regions in India- the Himalayas, the Gangetic Plains, the Highlands of Central India, the Western and Eastern Ghats, the semi-arid desert in the West, the Deccan Plateau, the Coastal Belts, and the Andaman and Nicobar Islands. These geographically distinctive areas have plants and animals that have been adapted to live in each of these regions. Arunodaya University - School of Arts, Humanities and Social Science 17 At an even more local level, each area has several structurally and functionally identifiable ecosystems systemssuch as different types of forests, grasslands, river catchments, mangrove swamps in deltas, seashores, islands, etc. to give only a few examples. Here too each of these forms a habitat for specific plants and animals. Ecosystems have been formed on land and in the sea by evolution that has created species to live together in a specific region. Thus ecosystems have both non-living and living components that are typical to an area giving it its own special characteristics that are easily observed. Some ecosystems are fairly robust and are less affected by a certain level of human disturbance. Others are highly fragile and are quickly destroyed by human activities. Mountain ecosystems are extremely fragile as degradation of forest cover leads to severe erosion of soil and changes in river courses. Island ecosystems are easily affected by any form of human activity which can lead to the rapid extinction of several of their unique species of plants and animals. Evergreen forests and coral reefs are also examples of species rich fragile ecosystems which must be protected against a variety of human activities that lead to their degradation. River and wetland ecosystems can be seriously affected by pollution and changes in surrounding landuse. Understanding ecosystems Natural ecosystems include the forests, grasslands, deserts, and aquatic ecosystems such as ponds, rivers, lakes, and the sea. Man modified ecosystems include agricultural land and urban or industrial land use patterns. Each ecosystem has a set of common features that can be observed in the field: ‘What does the ecosystem look like?’ One should be able to describe specific features of the different ecosystems in ones own surroundings. Field observations must be made in both urban and natural surroundings. What is its structure? Arunodaya University - School of Arts, Humanities and Social Science 18 Is it a forest, a grassland, a water body, an agricultural area, a grazing area, an urban area, an industrial area, etc.? What you should see are its different characteristics. A forest has layers from the ground to the canopy. A pond has different types of vegetation from the periphery to its center. The vegetation on a mountain changes from its base to its summit. What is the composition of its plant and animal species? List the well-known plants and animals you can see. Document their abundance and numbers in nature: very common, common, uncommon, rare. Wild mammals will not be seen in large numbers, cattle would be common. Some birds are common - which are the most common species? Insect species are very common and most abundant. In fact there are so many that they cannot be easily counted. ‘How does the ecosystem work’? The ecosystem functions through several biogeochemical cycles and energy transfer mechanisms. Observe and document the components of the ecosystem which consists of its non-living or abiotic features such as air, water, climate and soil. Its biotic components, the various plants and animals. Both these aspects of the ecosystem interact with each other through several functional aspects to form Nature’s ecosystems. Plants, herbivores and carnivores can be seen to form food chains. All these chains are joined together to form a ‘web of life’ on which man depends. Each of these use energy that comes from the sun and powers the ecosystem. Ecosystem degradation Ecosystems are the basis of life itself! The natural ecosystems in the wilderness provide a variety of products and are regions in which a number of vital ecological processes are present, without which human civilization would not be able to exist. Ecosystems are however frequently disrupted by human actions which lead to the extinction of species of plants and animals that can live only in the different natural ecosystems. Some Arunodaya University - School of Arts, Humanities and Social Science 19 species if eliminated seriously affect the ecosystem. These are called ‘keystone’ species. Extinction occurs due to changes in land use. Forests are deforested for timber, wetlands are drained to create more agricultural land and semi arid grasslands that are used as pastures are changed into irrigated fields. Pollution from industry and waste from urban settings can also lead to extinction of several species. The reason for the depletion of natural resources is twofold - our rapidly exploding population that needs to sustain itself on resources, and the growth of affluent societies, which consume and waste a very large proportion of resources and energy. Increasing extraction of resources is at the cost of natural ecosystems, leading to a derangement of their important functions. Each of us in our daily lives use a variety of resources. If tracked back to their source, one finds that the resources were originally obtained from nature and natural ecosystems. Our insensitivity to using resources carefully has produced societies that nature can no longer sustain. If one thinks before wasting resources such as water, reusing and recycling paper, using less plastics that are non-degradable, culminatively this can have positive implications on the integrity of our natural resource base and conserve the resources that nature provides. Resource utilisation Most traditional societies used their environment sustainably. Though inequality in resource utilization has existed in every society, the number of individuals that used a large proportion of resources was extremely limited. In recent times the proportion of ‘rich’ people in affluent societies, grew rapidly. Inequality thus became a serious problem. Whereas in the past many resources such as timber and fuel wood from the forest were extracted sustainably, this pattern has drastically changed during the last century. The economically better off sections began to use greater amounts of forest products, while those people who lived in the forest became increasingly poor. Similarly the building of large irrigation projects led to wealth in those areas that had canals, while those who hand to remain dependent on a constant supply of water from the river itself, found it difficult to survive. Structure and function of ecosystem Arunodaya University - School of Arts, Humanities and Social Science 20 Since each ecosystem has a non-living and a living part that are linked to each other, one needs to look around us and observe this closely. This is an important aspect that is a vital part of our lives. The non-living components of an ecosystem are the amount of water, the various inorganic substances and organic compounds, and climatic conditions such as rainfall and temperature, which depend on geographical conditions and location which is also related to the amount of sunlight. The living organisms in an ecosystem are inseparable from their habitat. The living component of plant life ranges from extremely small bacteria, which live in air, water and soil, algae which live in fresh and salt water, to the terrestrial plants which range from grasses and herbs that grow after the monsoon every year, to the giant long-lived trees of the forest. The plants convert energy from sunlight into organic matter for their growth. They thus function as producers in the ecosystem. The living component of the animal world ranges from microscopic animals, to small insects and the larger animals such as fish, amphibia, reptiles, birds and mammals. Man is just one of the 1.8 million species of plants and animals that inhabit the earth. Every living organism is in some way dependent on other organisms. Plants are food for herbivorous animals which are in turn food for carnivorous animals. Thus there are different tropic levels in the ecosystem. Some organisms such as fungi live only on dead material and inorganic matter. Plants are the ‘producers’ in producers the ecosystem as they manufacture their food by using energy from the sun. In the forest these form communities of plant life. In the sea these include tiny algal forms to large seaweed. The herbivorous animals herbivorous animals are primary consumers as they live on the producers. In a forest, these are the insects, amphibia, reptiles, birds and mammals. The herbivorous animals include for example hare, deer and elephants that live on plant life. They graze on grass or feed on the foliage from trees. In grasslands, there are herbivores such as the blackbuck that feed on grass. In the semiarid areas, there are species such as the chinkara or Indian gazelle. In the sea, there are small fish that live on algae and other plants. Arunodaya University - School of Arts, Humanities and Social Science 21 The structure of an ecosystem is characterised by the organisation of both biotic and abiotic components. This includes the distribution of energy in our environment. It also includes the climatic conditions prevailing in that particular environment. The structure of an ecosystem can be split into two main components, namely: Biotic Components Biotic components refer to all life in an ecosystem. Based on nutrition, biotic components can be categorised into autotrophs, heterotrophs and saprotrophs (or decomposers). Abiotic Components Abiotic components are the non-living component of an ecosystem. It includes air, water, soil, minerals, sunlight, temperature, nutrients, wind, altitude, turbidity, etc. The biotic and abiotic components are interrelated in an ecosystem. It is an open system where the energy and components can flow throughout the boundaries. Energy flow in an ecosystem: food chains, food webs and ecological succession Every ecosystem has several interrelated mechanisms that affect human life. These are the water cycle, the carbon cycle, the oxygen cycle, the nitrogen cycle and the energy cycle. While every ecosystem is controlled by these cycles, in each ecosystem its abiotic and biotic features are distinct from each other. All the functions of the ecosystem are in some way related to the growth and regeneration of its plant and animal species. These linked processes can be depicted as the various cycles. These processes depend on energy from sunlight. During photosynthesis carbon dioxide is taken up by plants and oxygen is released. Animals depend on this oxygen for their respiration. The water cycle depends on the rainfall, which is necessary for plants and animals to live. The energy cycle recycles nutrients into the soil on which plant life grows. Our own lives are closely linked to the proper functioning of these cycles of life. If human activities go on altering them, humanity cannot survive on our earth. Arunodaya University - School of Arts, Humanities and Social Science 22 The transfer of energy from the source in plants through a series of organisms by eating and being eaten constitutes food chains. At each transfer, a large proportion of energy is lost in the form of heat. These food chains are not isolated sequences, but are interconnected with each other. This interlocking pattern is known as the food web. Each step of the food web is called a trophic level. Hence green plants occupy the first level, herbivores the second level, carnivores the third level and secondary carnivores the fourth level. These trophic levels together form the ecological pyramid. Food Chains The most obvious aspect of nature is that energy must pass from one living organism to another. When herbivorous animals feed on plants, energy is transferred from plants to animals. In an ecosystem, some of the animals feed on other living organisms, while some feed on dead organic matter. The latter form the ‘detritus’ food chain. At each linkage in the chain, a major part of the energy from the food is lost for daily activities. Each chain usually has only four to five such links. However a single species may be linked to a large number of species. The sun is the ultimate source of energy on earth. It provides the energy required for all plant life. The plants utilise this energy for the process of photosynthesis, which is used to synthesise their food. During this biological process, light energy is converted into chemical energy and is passed on through successive levels. The flow of energy from a producer, to a consumer and eventually, to an apex predator or a detritivore is called the food chain. Dead and decaying matter, along with organic debris, is broken down into its constituents by scavengers. The reducers then absorb these constituents. After gaining the energy, the reducers liberate molecules to the environment, which can be utilised again by the producers. The food webs In an ecosystem there are a very large number of interlinked chains. This forms a food web. If the linkages in the chains that make up the web of life are disrupted due to human activities that lead to the loss or extinction of species, the web breaks down. Arunodaya University - School of Arts, Humanities and Social Science 23 Food web is an important ecological concept. Basically, food web represents feeding relationships within a community (Smith and Smith 2009). It also implies the transfer of food energy from its source in plants through herbivores to carnivores (Krebs 2009). Normally, food webs consist of a number of food chains meshed together. Each food chain is a descriptive diagram including a series of arrows, each pointing from one species to another, representing the flow of food energy from one feeding group of organisms to another. Food web is a network of interconnected food chains. It comprises all the food chains within a single ecosystem. It helps in understanding that plants lay the foundation of all the food chains. In a marine environment, phytoplankton forms the primary producer. Ecological succession Ecological succession is a process through which ecosystems tend to change over a period of time. Succession can be related to seasonal environmental changes, which create changes in the community of plants and animals living in the ecosystem. Other successional events may take much longer periods of time extending to several decades. If a forest is cleared, it is initially colonized by a certain group of species of plants and animals, which gradually change through an orderly process of community development. One can predict that an opened up area will gradually be converted into a grassland, a shrubland and finally a woodland and a forest if permitted to do so without human interference. There is a tendency for succession to produce a more or less stable state at the end of the successional stages. Developmental stages in the ecosystem thus consist of a pioneer stage, a series of changes known as serel stages, and finally a climax stage. The successive stages are related to the way in which energy flows through the biological system. The most frequent example of successional changes occur in a pond ecosystem where it fluctuates from a dry terrestrial habitat to the early colonisation stage by small aquatic species after the monsoon, which gradually passes through to a mature aquatic ecosystem, and then reverts back to its dry stage in summer where its aquatic life remains dormant. Case studies of the following ecosystems: a. Forest ecosystem Arunodaya University - School of Arts, Humanities and Social Science 24 Forests are formed by a community of plants which is predominantly structurally defined by its trees, shrubs, climbers and ground cover. Natural vegetation looks vastly different from a group of planted trees, which are in orderly rows. The most ‘natural’ undisturbed forests are located mainly in our National Parks and Wildlife Sanctuaries. The landscapes that make up various types of forests look very different from each other. Their distinctive appearance is a fascinating aspect of nature. Each forest type forms a habitat for a specific community of animals that are adapted to live in it. What is a forest ecosystem? The forest ecosystem has two parts: The non-living or abiotic aspects of the forest: The type of forest depends upon the : abiotic conditions at the site. Forests on mountains and hills differ from those along river valleys. Vegetation is specific to the amount of rainfall and the local temperature which varies according to latitude and altitude. Forests also vary in their plant communities in response to the type of soil. The living or the biotic aspects of the forest: The plants and animals form communities that are specific to each forest type. For instance coniferous trees occur in the Himalayas. Mangrove trees occur in river deltas. Thorn trees grow in arid areas. The snow leopard lives in the Himalayas while the leopard and tiger live in the forests of the rest of India. Wild sheep and goats live high up in the Himalayas. Many of the birds of the Himalayan forests are different from the rest of India. Evergreen forests of the Western Ghats and North East India are most rich in plant and animal species. Forest types in India: Forest types in India: The forest type depends upon the abiotic factors such as climate and soil characteristics of a region. Forests in India can be broadly divided into Coniferous forests and Broadleaved forests. They can also be classified according to the nature of their tree species - evergreen, deciduous, xerophytic or thorn trees, mangroves, etc. They can also be classified according to the most Arunodaya University - School of Arts, Humanities and Social Science 25 abundant species of trees such as Sal or Teak forests. In many cases a forest is named after the first three or four most abundant tree species. Coniferous forests grow in the Himalayan mountain region, where the temperatures are low. These forests have tall stately trees with needle like leaves and downward sloping branches so that the snow can slip off the branches. They have cones instead of seeds and are called gymnosperms. Broadleaved forests have several types, such as evergreen forests, deciduous forests, thorn forests, and mangrove forests. Broadleaved forests have large leaves of various shapes. Evergreen forests grow in the high rainfall areas of the Western Ghats, North Eastern India and the Andaman and Nicobar Islands. These forests grow in areas where the monsoon lasts for several months. Some even get two monsoons, such as in Southern India. Evergreen plants shed a few of their leaves throughout the year. There is no dry leafless phase as in a deciduous forest. An evergreen forest thus looks green throughout the year. The trees overlap with each other to form a continuous canopy. Thus very little light penetrates down to the forest floor. Only a few shade loving plants can grow in the ground layer in areas where some light filters down from the closed canopy. The forest is rich in orchids and ferns. The barks of the trees are covered in moss. The forest abounds in animal life and is most rich in insect life. b. Grassland ecosystem A wide range of landscapes in which the vegetation is mainly formed by grasses and small annual plants are adapted to India’s various climatic conditions. These form a variety of grassland ecosystems with their specific plants and animals. What is a grassland ecosystem? Grasslands cover areas where rainfall is usually low and/or the soil depth and quality is poor. The low rainfall prevents the growth of a large number of trees and shrubs, but is sufficient to support the growth of grass cover during the monsoon. Many of the grasses and other small herbs become dry and the part above the ground dies during the summer months. In the next monsoon the grass cover grows back from the root stock and the seeds of the previous year. Arunodaya University - School of Arts, Humanities and Social Science 26 This change gives grasslands a highly seasonal appearance with periods of increased growth followed by a dormant phase. A variety of grasses, herbs, and several species of insects, birds and mammals have evolved so that they are adapted to these wide-open grass covered areas. These animals are able to live in conditions where food is plentiful after the rains, so that they can store this as fat that they use during the dry period when there is very little to eat. Man began to use these grasslands as pastures to feed his livestock when he began to domesticate animals and became a pastoralist in ancient times. Grassland Types in India: Grasslands form a variety of ecosystems that are located in different climatic conditions ranging from near desert conditions, to patches of shola grasslands that occur on hillslopes alongside the extremely moist evergreen forests in South India. In the Himalayan mountains there are the high cold Himalayan pastures. There are tracts of tall elephant grass in the low-lying Terai belt south of the Himalayan foothills. There are semi-arid grasslands in Western India, parts of Central India, and in the Deccan Plateau. The Himalayan pasture belt Himalayan pasture belt extends upto the snowline. The grasslands at a lower level form patches along with coniferous or broadleaved forests. Himalayan wildlife require both the forest and the grassland ecosystem as important parts of their habitat. The animals migrate up into the high altitude grasslands in summer and move down into the forest in winter when the snow covers the grassland. These Himalayan pastures have a large variety of grasses and herbs. Himalayan hill slopes are covered with thousands of colourful flowering plants. There are also a large number of medicinal plants. The Terai consists of patches of tall grasslands interspersed with a Sal forest ecosystem. The patches of tall elephant grass, which grows to a height of about five meters, are located in the low-lying waterlogged areas. The Sal forest patches cover the elevated regions and the Himalayan foothills. The Terai also includes marshes in low-lying depressions. This ecosystem extends as a belt south of the Himalayan foothills. Arunodaya University - School of Arts, Humanities and Social Science 27 How are grasslands used? Grasslands are the grazing areas of many rural communities. Farmers who keep cattle or goats, as well as shepherds who keep sheep, are highly dependent on grasslands. Domestic animals are grazed in the ‘common’ land of the village. Fodder is collected and stored to feed cattle when there is no grass left for them to graze in summer. Grass is also used to thatch houses and farm sheds. The thorny bushes and branches of the few trees that are seen in grasslands are used as a major source of fuelwood. Overgrazing by huge herds of domestic livestock has degraded many grasslands. Grasslands have diverse species of insects that pollinate crops. There are also predators of these insects such as the small mammals like shrews, reptiles like lizards, birds of prey, and amphibia such as frogs and toads. All these carnivorous animals help to control insect pests in adjoining agricultural lands. What are the threats to grassland ecosystems? In many areas grasslands have been used for centuries by pastoral communities. Overutilization and changes in landuse of the ‘common grazing lands’ of rural communities has lead to their degradation. The grassland cover in the country in terms of permanent pastures now covers only 3.7 percent of land. A major threat to natural grasslands is the conversion of grasslands into irrigated farmlands. In the Deccan, grasslands have been altered to irrigated farms and are now mainly used to grow sugarcane. After continuous irrigation such land becomes saline and useless in a few years. More recently many of these residual grassland tracts have been converted into industrial areas. This provides short-term economic gains but result in long-term economic and ecological losses. Grasslands have a limited ability to support domestic animals and wildlife. Increasing this pressure by increasing the number of domestic animals reduces the ‘naturalness’ of the grassland ecosystem leading to its degradation. Most grassland ecosystems are highly modified by human activities. Cattle, sheep and goat grazing, and lighting repeated fires affects grasslands adversely. Changing the grasslands to Arunodaya University - School of Arts, Humanities and Social Science 28 other forms of landuse such as agriculture, tree plantations and industrialisation forms a serious threat to this highly productive ecosystem. Thus some of the grassland patches which are in a less disturbed state and have retained their special plants and animals need to be urgently protected. Degradation of grasslands due to over grazing by cattle, sheep and goats occurs if more than a critical number of domestic animals are present in the grasslands. When animals overgraze the area, the grasses are converted into flat stubs with very little green matter. Degraded grasslands have fewer grass species as the nutritious species are entirely used up by the large number of domestic animals. They are thus unable to regenerate. When fires are lit in the grasslands in summer, the burnt grass gets a fresh flush of small green shoots which the domestic animals graze on. If this is done too frequently the grasslands begin to deteriorate. Finally grasslands become bare, the soil is solidly compacted by trampling, or is washed away during the monsoon by rain and whipped into dust storms during the hot dry summer. The land is degraded, as there is no grass to hold the soil in place. It becomes a wasteland. c. Desert ecosystem Desert and semi arid lands are highly specialised and sensitive ecosystems that are easily destroyed by human activities. The species of these dry areas can live only in this specialised habitat. What is a desert or a semi-arid ecosystem? Deserts and semi arid areas are located in Western India and the Deccan Plateau. The climate in these vast tracts is extremely dry. There are also cold deserts such as in Ladakh, which are located in the high plateaus of the Himalayas. The most typical desert landscape that is seen in Rajasthan is in the Thar Desert. This has sand dunes. There are also areas covered with sparse grasses and a few shrubs, which grow if it rains. In most areas of the Thar the rainfall is scanty and sporadic. In an area it may rain only once every few years. In the adjoining semi arid tract the vegetation consists of a few shrubs and thorny trees such as kher and babul. Arunodaya University - School of Arts, Humanities and Social Science 29 The Great and Little Rann of Kutch are highly specialised arid ecosystems. In the summers they are similar to a desert landscape. However as these are low-lying areas near the sea, they get converted to salt marshes during the monsoons. During this period they attract an enormous number of aquatic birds such as ducks, geese, cranes, storks, etc. The Great Rann is famous, as it is the only known breeding colony of the Greater and Lesser Flamingos in our country. The Little Rann of Kutch is the only home of the wild ass in India. Desert and semi arid regions have a number of highly specialized insects and reptiles. The rare animals include the Indian wolf, desert cat, desert fox and birds such as the Great Indian Bustard and the Florican. Some of the commoner birds include partridges, quails and sandgrouse. How are desert and semi-arid ecosystems used? Areas of scanty vegetation with semi-arid scrubland have been used for camel, cattle and goat grazing in Rajasthan and Gujarat, and for sheep grazing in the Deccan Plateau. Areas that have a little moisture, such as along the watercourses, have been used for growing crops such as jowar, and bajra. The natural grasses and local varieties of crops have adapted to growing at very low moisture levels. These can be used for genetic engineering and developing arid land crops for the future. What are the threats to desert ecosystems? Several types of development strategies as well as human population growth have begun to affect the natural ecosystem of the desert and semi arid land. Conversion of these lands through Arunodaya University - School of Arts, Humanities and Social Science 30 extensive irrigation systems has changed several of the natural characteristics of this region. The canal water evaporates rapidly bringing the salts to the surface. The region becomes highly unproductive as it becomes saline. Pulling excessive groudwater from tube wells lowers the water table creating an even drier environment. Thus human activities destroy the naturalness of this unique ecosystem. The special species that evolved here over millions of years may soon become extinct. How can desert ecosystems be conserved? Desert ecosystems are extremely sensitive. Their ecological balance that forms a habitat for their plants and animals is easily disturbed. Desert people have traditionally protected their meagre water resources. The Bishnois in Rajasthan are known to have protected their Khejdi trees and the blackbuck antelope for several generations. The tradition began when the ruler of their region ordered his army to cut down trees for his own use. Several Bishnois were said to have been killed while trying to protect their trees. There is an urgent need to protect residual patches of this ecosystem within National Parks and Wildlife Sanctuaries in desert and semi arid areas. The Indira Gandhi Canal in Rajasthan is destroying this important natural arid ecosystem, as it will convert the region into intensive agriculture. In Kutch, areas of the little Rann, which is the only home of the Wild Ass, will be destroyed by the spread of salt works. Development Projects alter the desert and arid landscape. There is a sharp reduction in the habitat available for its specialised species bringing them to the verge of extinction. We need a sustainable form of development that takes the special needs of the desert into account. d. Aquatic ecosystems (ponds, streams, lakes, rivers, oceans, estuaries) The aquatic ecosystems constitute the marine environments of the seas and the fresh water systems in lakes, rivers, ponds and wetlands. These ecosystems provide human beings with a wealth of natural resources. They provide goods that people collect for food such as fish and crustaceans. Natural aquatic systems such as rivers and seas break down chemical and organic Arunodaya University - School of Arts, Humanities and Social Science 31 wastes created by man. However, this function has limitations, as the aquatic ecosystem cannot handle great quantities of waste. Beyond a certain limit, pollution destroys this natural function. If aquatic ecosystems are misused or over utilized, their ability to provide resources suffers in the long term. Over-fishing leads to a fall in the fish catch. River courses that are changed by dams to provide electricity affect thousands of people who do not get a continuous supply of water downstream for their daily use. When wetlands are drained, their connected rivers tend to cause floods. These are all examples of unsustainable changes in the use of natural resources and nature’s ecosystems that are dependent on hydrological regimes. Water is an important factor in all our ecosystems. Several ecosystems exist in freshwater and marine salt water. There is very little fresh water on earth, which is a key resource for people all over the world. What is an aquatic ecosystem? In aquatic ecosystems, plants and animals live in water. These species are adapted to live in different types of aquatic habitats. The special abiotic features are its physical aspects such as the quality of the water, which includes its clarity, salinity, oxygen content and rate of flow. Aquatic ecosystems may be classified as being stagnant stagnant stagnant ecosystems, or running water running water running water ecosystems. The mud gravel or rocks that form the bed of the aquatic ecosystem alter its characteristics and influence its plant and animal species composition. The aquatic ecosystems are classified into freshwater freshwater, freshwater brackish brackish and marine ecosystems, which are based on the salinity levels. Arunodaya University - School of Arts, Humanities and Social Science 32 The fresh water ecosystems that have running water are streams and rivers. Ponds, tanks and lakes are ecosystems where water does not flow. Wetlands are special ecosystems in which the water level fluctuates dramatically in different seasons. They have expanses of shallow water with aquatic vegetation, which forms an ideal habitat for fish, crustacea and water birds. Marine ecosystems are highly saline, while brackish areas have less saline water such as in river deltas. Coral reefs are very rich in species and are found in only a few shallow tropical seas. The richest coral reefs in India are around the Andaman and Nicobar islands and in the gulf of Kutch. Brackish water ecosystems in river deltas are covered by mangrove forests and are among the world’s most productive ecosystems in terms of biomass production. The largest mangrove swamps are in the Sunderbans in the delta of the Ganges. The Pond ecosystem The pond is the simplest aquatic ecosystem to observe. There are differences in a pond that is temporary and has water only in the monsoon, and a larger tank or lake that is an aquatic ecosystem throughout the year. Most ponds become dry after the rains are over and are covered by terrestrial plants for the rest of the year. When a pond begins to fill during the rains, its life forms such as the algae and microscopic animals, aquatic insects, snails, and worms come out of the floor of the pond where they have remained dormant in the dry phase. Gradually more complex animals such as crabs frogs and fish return to the pond. The vegetation in the water consists of floating weeds and rooted vegetation on the periphery which grow on the muddy floor under water and emerge out of the surface of the water. As the pond fills in the monsoon a large number of food chains are formed. Algae is eaten by microscopic animals, which are in turn eaten by small fish on which larger carnivorous fish depend. These are in turn eaten by birds such as kingfishers, herons and birds of prey. Aquatic insects, worms and snails feed on the waste material excreted by animals and the dead or decaying plant and animal matter. They act on the detritus, which is broken down into nutrients which aquatic plants can absorb, thus completing the nutrient cycle in the pond. The temporary Arunodaya University - School of Arts, Humanities and Social Science 33 ponds begin to dry after the rains and the surrounding grasses and terrestrial plants spread into the moist mud that is exposed. Animals such as frogs, snails and worms remain dormant in the mud, awaiting the next monsoon. Lake ecosystem A lake ecosystem functions like a giant permanent pond. A large amount of its plant material is the algae, which derives energy from the sun. This is transferred to the microscopic animals, which feed on the algae. There are fish that are herbivorous and are dependent on algae and aquatic weeds. The small animals such as snails are used as food by small carnivorous fish, which in turn are eaten by larger carnivorous fish. Some specialised fish, such as catfish, feed on the detritus on the muddy bed of the lake. Energy cycles through the lake ecosystem from the sunlight that penetrates the water surface to the plants. From plants energy is transferred to herbivorous animals and carnivores. Animals excrete waste products, which settle on the bottom of the lake. This is broken down by small animals that live in the mud in the floor of the lake. This acts as the nutrient material that is used by aquatic plants for their growth. During this process plants use Carbon from CO2 for their growth and in the process release Oxygen. This Oxygen is then used by aquatic animals, which filter water through their respiratory system. Stream and River ecosystems Streams and rivers are flowing water ecosystems in which all the living forms are specially adapted to different rates of flow. Some plants and animals such as snails and other burrowing animals can withstand the rapid flow of the hill streams. Other species of plants and animals such as water beetles and skaters can live only in slower moving water. Some species of fish, such as Mahseer, go upstream from rivers to hill streams for breeding. They need crystal clear water to be able to breed. They lay eggs only in clear water so that their young can grow successfully. Arunodaya University - School of Arts, Humanities and Social Science 34 As deforestation occurs in the hills the water in the streams that once flowed throughout the year become seasonal. This leads to flash floods in the rains and a shortage of water once the streams dry up after the monsoon. The community of flora and fauna of streams and rivers depends on the clarity, flow and oxygen content as well as the nature of their beds. The stream or river can have a sandy, rocky or muddy bed, each type having its own species of plants and animals. Marine ecosystems The Indian Ocean, the Arabian Sea and the Bay of Bengal constitute the marine ecosystems around peninsular India. In the coastal area the sea is shallow while further away, it is deep. Both these are different ecosystems. The producers in this ecosystem vary from microscopic algae to large seaweeds. There are millions of zooplankton and a large variety of invertebrates on which live fish, turtles and marine mammals. The shallow areas near Kutch and around the Andaman and Nicobar Islands are some of the most incredible coral reefs in the world. Coral reefs are only second to tropical evergreen forests in their richness of species. Fish, crustacea, starfish, jellyfish and the polyps that deposit the coral are a few of the thousands of species that form this incredible world under the shallow sea. Deforestation of adjacent mangroves leads to silt being carried out to sea where it is deposited on the coral which then dies. There are many different types of coastal ecosystems which are highly dependent on the tide. The marine ecosystem is used by coastal fisherfolk for fishing which forms their livelihood. In the past, fishing was done at a sustainable level. The marine ecosystem continued to maintain its abundant supply of fish over many generations. Now with intensive fishing by using giant nets and mechanised boats, fish catch in the Indian Ocean has dropped significantly. Seashore ecosystems Arunodaya University - School of Arts, Humanities and Social Science 35 Beaches can be sandy, rocky, shell covered or muddy. On each of these different types, there are several specific species which have evolved to occupy a separate niche. There are different crustacea such as crabs that make holes in the sand. Various shore birds feed on their prey by probing into the sand or mud on the sea shore. Several different species of fish are caught by fishermen. In many areas the fish catch has decreased during the last decade or two. How are aquatic ecosystems used? Man uses aquatic ecosystems for the clean freshwater on which his life is completely dependent. We need clean water to drink and for other domestic uses. Water is essential for agriculture. Fisherfolk use the aquatic ecosystems to earn a livelihood. People catch fish and crabs. They also collect edible plants. This is used locally as food or for sale in the market. Over fishing leads to a serious decline in the catch and a long-term loss of income for fisherfolk. Marshes and wetlands are of great economic importance for people who live on their fish, crustacea, reeds, grasses and other produce. Modern man impounds water in dams to be able to store it throughout the year. Agriculture and industry are highly dependent on large quantities of water. However this leads to problems for tribal people who have lived there before the dams were built as they are displaced to build large dams. These dams make rich people richer in the farmland and supports people in large urban centres that use enormous quantities of water. The poor tribal folk become even poorer as the natural resources they depend on are taken away as their lands are submerged under the water of the dam. Dams are built across rivers to generate electricity. A large proportion of this energy is used by urban people, by agriculturists in irrigated farmlands and in enormous quantities for industry. Large dams have serious ill effects on natural river ecosystems. While water from dams used for irrigation has lead to economic prosperity in some areas, in semiarid areas that are artificially irrigated the high level of evaporation leads to severe salinisation as salts are brought up into Arunodaya University - School of Arts, Humanities and Social Science 36 the surface layers of the soil. This makes such lands gradually more and more saline and unproductive. What are the threats to aquatic ecosystems? Water pollution occurs from sewage and poorly managed solid waste in urban areas when it enters the aquatic ecosystem of lakes and rivers. Sewage leads to a process called eutrophication, which destroys life in the water as the oxygen content is severely reduced. Fish and crustacea cannot breathe and are killed. A foul odour is produced. Gradually the natural flora and fauna of the aquatic ecosystem is destroyed. In rural areas the excessive use of fertilisers causes an increase in nutrients, which leads to eutrophication. Pesticides used in adjacent fields pollute water and kills off its aquatic animals. Chemical pollution from industry kills a large number of life forms in adjacent aquatic ecosystems. Contamination by heavy metals and other toxic chemicals affects the health of people who live near these areas as they depend on this water. CASE STUDY Threats to wetlands in Assam Almost 40% of all wetlands in Assam are under threat. A survey conducted by the Assam Remote Sensing Application Center (ARSAC), Guwahati, and the Space Research Center, Ahemadabad, has revealed that 1367 out of 3513 wetlands in Assam are under severe threat due to invasion of aquatic weeds and several developmental activities. The wetlands of Assam form the greatest potential source of income for the State in terms of fisheries and tourism. Though the wetlands of Assam have the capacity of producing 5,000 tones of fish per hectare per year, around 20,000 tones of fish have to be imported to meet local demands. This is primarily due to poor wetland management. Questions: 1. Define structure and function of ecosystem? 2. What are the main types of freshwater ecosystems? Arunodaya University - School of Arts, Humanities and Social Science 37 3. How is a food web related to energy flow within an ecosystem? 4. How can desert ecosystems be conserved? ********** Arunodaya University - School of Arts, Humanities and Social Science 38 Unit 3: Natural Resources: Renewable and Non-renewable Resources Land resources and land use change Landforms such as hills, valleys, plains, river basins and wetlands include different resource generating areas that the people living in them depend on. Many traditional farming societies had ways of preserving areas from which they used resources. Eg. In the ‘sacred groves’ of the Western Ghats, requests to the spirit of the Grove for permission to cut a tree, or extract a resource, were accompanied by simple rituals. The outcome of a chance fall on one side or the other of a stone balanced on a rock gave or withheld permission. The request could not be repeated for a specified period. If land is utilized carefully it can be considered a renewable resource. The roots of trees and grasses bind the soil. If forests are depleted, or grasslands overgrazed, the land becomes unproductive and wasteland is formed. Intensive irrigation leads to water logging and salination, on which crops cannot grow. Land is also converted into a non- renewable resource when highly toxic industrial and nuclear wastes are dumped on it. Land on earth is as finite as any of our other natural resources. While mankind has learnt to adapt his lifestyle to various ecosystems world over, he cannot live comfortably for instance on polar ice caps, on under the sea, or in space in the foreseeable future. Arunodaya University - School of Arts, Humanities and Social Science 39 Man needs land for building homes, cultivating food, maintaining pastures for domestic animals, developing industries to provide goods, and supporting the industry by creating towns and cities. Equally importantly, man needs to protect wilderness area in forests, grasslands, wetlands, mountains, coasts, etc. to protect our vitally valuable biodiversity. Thus a rational use of land needs careful planning. One can develop most of these different types of land uses almost anywhere, but Protected Areas (National Park’s and Wildlife Sanctuaries) can only be situated where some of the natural ecosystems are still undisturbed. These Protected Areas are important aspects of good landuse planning. Land degradation Farmland is under threat due to more and more intense utilisation. Every year, between 5 to 7 million hectares of land worldwide is added to the existing degraded farmland. When soil is used more intensively by farming, it is eroded more rapidly by wind and rain. Over irrigating farmland leads to salinisation, as evaporation of water brings the salts to the surface of the soil on which crops cannot grow. Over irrigation also creates water logging of the topsoil so that crop roots are affected and the crop deteriorates. The use of more and more chemical fertilizers poisons the soil so that eventually the land becomes unproductive. As urban centers grow and industrial expansion occurs, the agricultural land and forests shrink. This is a serious loss and has long term ill effects on human civilisation. Land degradation is one of the world’s most pressing environmental problems and it will worsen without rapid remedial action. Globally, about 25 percent of the total land area has been degraded. When land is degraded, soil carbon and nitrous oxide is released into the atmosphere, making land degradation one of the most important contributors to climate change. Scientists recently warned that 24 billion tons of fertile soil was being lost per year, largely due to unsustainable agriculture practices. If this trend continues, 95 percent of the Earth’s land areas could become degraded by 2050. Globally, 3.2 billion people are affected by land degradation, especially rural communities, smallholder farmers, and the very poor. The world population is projected to increase by about Arunodaya University - School of Arts, Humanities and Social Science 40 35 percent to 9.7 billion in 2050, with rising demands for agricultural products including food, feed, fiber, and fuel. However, pressure on the global land resource is increasing due to other factors as well, such as agricultural production systems made less resilient by the loss of biodiversity, and natural factors such as climate variability and extreme weather events. Climate change exacerbates variations in yields and income from agriculture, threatening the resilience of agro-ecosystems and stability of food production systems. Land degradation has accelerated during the 20th and 21st centuries due to increasing and combined pressures of agricultural and livestock production (over-cultivation, overgrazing, forest conversion), urbanization, deforestation and extreme weather events such as droughts and coastal surges, which salinate land. Land degradation results from a complex chain of causes making the clear distinction between direct and indirect drivers difficult. In the context of climate change, an additional complex aspect is brought by the reciprocal effects that both processes have on each other (i.e. climate change influencing land degradation and vice versa). In this chapter, we use the terms ‘processes’ and ‘drivers’ with the following meanings: Processes of land degradation are those direct mechanisms by which land is degraded and are similar to the notion of ‘direct drivers’ in the Millennium Ecosystem Assessment framework (Millennium Ecosystem Assessment, 2005). Drivers of land degradation are those indirect conditions which may drive processes of land degradation and are similar to the notion of ‘indirect drivers’ in the Millennium Ecosystem Assessment framework. Examples of indirect drivers of land degradation are changes in land tenure or cash crop prices, which can trigger land-use or management shifts that affect land degradation. An exact demarcation between processes and drivers is not possible. Drought and fires are described as drivers of land degradation in the next section but they can also be a process: for example, if repeated fires deplete seed sources, they can affect regeneration and succession of forest ecosystems. The responses to land degradation follow the Arunodaya University - School of Arts, Humanities and Social Science 41 logic of the LDN concept: avoiding, reducing and reversing land degradation (Orr et al. 2017; Cowie et al. 2018). In research on land degradation, climate and climate variability are often intrinsic factors. The role of climate change, however, is less articulated. Depending on what conceptual framework is used, climate change is understood either as a process or a driver of land degradation, and sometimes both. Processes of land degradation A large array of interactive physical, chemical, biological and human processes lead to what we define in this report as land degradation (Johnson and Lewis 2007). The biological productivity, ecological integrity (which encompasses both functional and structural attributes of ecosystems) or the human value (which includes any benefit that people get from the land) of a given territory can deteriorate as the result of processes triggered at scales that range from a single furrow (e.g., water erosion under cultivation) to the landscape level (e.g., salinisation through raising groundwater levels under irrigation). While pressures leading to land degradation are often exerted on specific components of the land systems (i.e., soils, water, biota), once degradation processes start, other components become affected through cascading and interactive effects. For example, different pressures and degradation processes can have convergent effects, as can be the case of overgrazing leading to wind erosion, landscape drainage resulting in wetland drying, and warming causing more frequent burning; all of which can independently lead to reductions of the soil organic matter (SOM) pools as a second-order process. Still, the reduction of organic matter pools is also a first-order process triggered directly by the effects of rising temperatures (Crowther et al. 2016) as well as other climate changes such as precipitation shifts (Viscarra Rossel et al. 2014). Beyond this complexity, a practical assessment of the major land degradation processes helps to reveal and categorise the multiple pathways in which climate change exerts a degradation pressure. Soil erosion and desertification The characteristics of natural ecosystems such as forests and grasslands depend on the type of soil. Soils of various types support a wide variety of crops. The misuse of an ecosystem leads to Arunodaya University - School of Arts, Humanities and Social Science 42 loss of valuable soil through erosion by the monsoon rains and, to a smaller extent, by wind. The roots of the trees in the forest hold the soil. Deforestation thus leads to rapid soil erosion. Soil is washed into streams and is transported into rivers and finally lost to the sea. The process is more evident in areas where deforestation has led to erosion on steep hill slopes as in the Himalayas and in the Western Ghats. These areas are called ‘ecologically sensitive areas’ or ESAs. To prevent the loss of millions of tons of valuable soil every year, it is essential to preserve what remains of our natural forest cover. It is equally important to reforest denuded areas. The linkage between the existence of forests and the presence of soil is greater than the forest’s physical soil binding function alone. The soil is enriched by the leaflitter of the forest. This detritus is broken down by soil micro-organisms, fungi, worms and insects, which help to recycle nutrients in the system. Further losses of our soil wealth will impoverish our country and reduce its capacity to grow enough food in future. The effects of soil erosion go beyond the loss of fertile land. It has led to increased pollution and sedimentation in streams and rivers, clogging these waterways and causing declines in fish and other species. And degraded lands are also often less able to hold onto water, which can worsen flooding. Sustainable land use can help to reduce the impacts of agriculture and livestock, preventing soil degradation and erosion and the loss of valuable land to desertification. The most effective way of minimizing erosion is to guarantee a permanent surface cover on the soil surface, such as trees, pasture, or meadow. However, compared to original forest soils, soils in pasture fields and croplands have less capacity to hold up and are more susceptible to erosion. These soils also have less capacity to absorb water, which makes flooding (and its economic, social, and environmental impacts) more common. Factors affecting soil erosion Climate The amount and intensity of precipitation is the main climatic factor governing soil erosion by water. The relationship is particularly strong if heavy rainfall occurs at times when, or in locations where, the soil's surface is not well protected by vegetation. This might be during periods when agricultural activities leave the soil bare, or in semi-arid regions where vegetation Arunodaya University - School of Arts, Humanities and Social Science 43 is naturally sparse. Wind erosion requires strong winds, particularly during times of drought when vegetation is sparse and soil is dry (and so is more erodible). Other climatic factors such as average temperature and temperature range may also affect erosion, via their effects on vegetation and soil properties. In general, given similar vegetation and ecosystems, areas with more precipitation (especially high-intensity rainfall), more wind, or more storms are expected to have more erosion. Soil structure and composition The composition, moisture, and compaction of soil are all major factors in determining the erosivity of rainfall. Sediments containing more clay tend to be more resistant to erosion than those with sand or silt, because the clay helps bind soil particles together. Soil containing high levels of organic materials are often more resistant to erosion, because the organic materials coagulate soil colloids and create a stronger, more stable soil structure. The amount of water present in the soil before the precipitation also plays an important role, because it sets limits on the amount of water that can be absorbed by the soil (and hence prevented from flowing on the surface as erosive runoff). Wet, saturated soils will not be able to absorb as much rain water, leading to higher levels of surface runoff and thus higher erosivity for a given volume of rainfall. Soil compaction also affects the permeability of the soil to water, and hence the amount of water that flows away as runoff. More compacted soils will have a larger amount of surface runoff than less compacted soils. Vegetative cover Vegetation acts as an interface between the atmosphere and the soil. It increases the permeability of the soil to rainwater, thus decreasing runoff. It shelters the soil from winds, which results in decreased wind erosion, as well as advantageous changes in microclimate. The roots of the plants bind the soil together, and interweave with other roots, forming a more solid mass that is less susceptible to both water and wind erosion. The removal of vegetation increases the rate of surface erosion. Topography Arunodaya University - School of Arts, Humanities and Social Science 44 The topography of the land determines the velocity at which surface runoff will flow, which in turn determines the erosivity of the runoff. Longer, steeper slopes (especially those without adequate vegetative cover) are more susceptible to very high rates of erosion during heavy rains than shorter, less steep slopes. Steeper terrain is also more prone to mudslides, landslides, and other forms of gravitational erosion processes. Deforestation: Causes and impacts due to mining Where civilizations have looked after forests by using forest resources cautiously, they have prospered, where forests were destroyed, the people were gradually impoverished. Today logging and mining are serious causes of loss of forests in our country and all over the world. Dams built for hydroelectric power or irrigation have submerged forests and have displaced tribal people whose lives are closely knit to the forest. This has become a serious cause of concern in India. One of India’s serious environmental problems is forest degradation due to timber extraction and our dependence on fuelwood. A large number of poor rural people are still highly dependent on wood to cook their meals and heat their homes. We have not been able to plant enough trees to support the need for timber and fuelwood. The National Forest Policy of 1988 now gives an added importance to JFM. Another resolution in 1990 provided a formal structure for community participation though the formation of Village Forest Committees. Based on these experiences, new JFM guidelines were issued in 2000. This stipulates that at least 25 per cent of the income from the area must go to the community. From the initiation of the program, until 2002, there were 63,618 JFM Committees managing over 140,953 sq. km of forest under JFM in 27 States in India. Mining is one of the main causes of deforestation. The environmental impact of mining includes soil erosion, formation of sinkholes, loss of biodiversity, and contamination of soil, groundwater and surface water by chemicals from mining processes. Mining occurs so as to extract precious metals and gemstones such as Manganese, tantalum, cassiterite, copper, tin, nickel, bauxite (aluminum ore), iron ore, gold, silver, and diamonds which are found in many tropical rainforests. These metal such as gold is then used to make jewellery. Mining is a destructive Arunodaya University - School of Arts, Humanities and Social Science 45 activity that damages the rainforest ecosystem and causes problems for people living nearby and downstream. Mining has a huge impact on those who are exposed to the toxic waste from the tailings. People living there may start to develop skin rashes, headaches, vomiting, diarrhea and other medical conditions. Many people who cannot afford to go to a doctor or live in a village where medication is not accessible, are often not treated for their illnesses and resulting in their death. Forests are cleared to establish the mines and construct roads to transport the materials. While deforestation and chemical pollution from mining can impact the rainforest environment, it can affect aquatic habitats even more. Reduced water flows caused by deforestation can seriously affect local fish populations. Nowadays natural resources are becoming scarce and rainforests have many quantities of raw materials such as plants, timber, gold and iron, all of which are currently being exploited illegally. Dam building on environment When asked to name different causes of deforestation, few people will mention hydroelectric dams as being one of them. Even fewer will include them as a cause of human rights violations. However, dams constitute a major direct and indirect cause of forest loss and most of them have resulted in widespread hu-man rights abuses. This lack of awareness can be explained by the fact that for many years large hydroelectric dams have been portrayed as synonymous with development. Another reason can be that most users of hydro-electricity live far away from the impacted areas and that the sites selected for dam building have been often those inhabited by indigenous peoples, tribal people, ethnic minorities and poor communities having little capacity of being heard by the wider national com-munity. The fact is that more than 40,000 large dams - those that measure more than 15 metres in height - are currently obstructing the world’s rivers, whose reservoirs cover more than 400,000 square kilometers of land. These reservoirs have inundated millions of hectares of forests - particularly in the tropics - many of which were not even logged and trees were left to slowly rot. They have also resulted in deforestation elsewhere, as farmers dis-placed by the dams have had to clear forests in other areas in order to grow their crops and build their homes. Additionally, Arunodaya University - School of Arts, Humanities and Social Science 46 dams imply road building, thus allowing access to previously remote areas by loggers and “developers”, resulting in further deforestation processes. However, the dams’ effects have included much more than forest loss and the major environmental changes have impacted on local people, at both the dam site and in the entire river basin. Not only are the best agricultural soils flooded by the reservoir, but major changes occur in the environment, where the river’s flora and fauna begins to disappear, with strong impacts on people dependent on those resources. At the same time, dams imply a number of health hazards, starting with diseases introduced by the thousands of workers that are brought in to build the dam (including AIDS, syphilis, tuberculosis, measles and others) and ending with diseases related to the reservoir itself (malaria, schistosomiasis, river blindness, etc.). In far too many cases, dam-building has resulted in widespread human rights violations. As most of us would, local peoples have persistently resisted the destruction of their homelands and their forced “resettlement.” As a result, they have had to face different types of repression, ranging from physical and legal threats to mass murders. But resistance, consciousness and solidarity have grown. Local people have in-creasingly been able to organize themselves and to establish local, national and international alliances with other concerned organizations. Major examples are the Narmada Bachao Andolan movement in India, the Bio Bio Action Group in Chile, the Coalition of Concerned NGOs on Bakun in Malaysia, the People Af-fected by Dams movement in Brazil among many others. It has now become possible to stop large hydro dams. They are definitely not a symbol of develop-ment but one of economic and political power resulting in social and environ-mental degradation. Large dams have had serious impacts on the lives, livelihoods, cultures and spiritual existence of indigenous and tribal peoples. They have suffered disproportionately from the negative impacts of dams and often been excluded from sharing the benefits. In India, of the 16 to 18 million Arunodaya University - School of Arts, Humanities and Social Science 47 people displaced by dams, 40 to 50% were tribal people, who account for only 8% of our nation’s one billion people. Conflicts over dams have heightened in the last two decades because of their social and environmental impacts and failure to achieve targets for sticking to their costs as well as achieving promised benefits. Recent examples show how failure to provide a transparent process that includes effective participation of local people has prevented affected people from playing an active role in debating the pros and cons of the project and its alternatives. The loss of traditional, local controls over equitable distribution remains a major source of conflict. Forests, biodiversity and tribal populations Scientists estimate that India should ideally have 33 percent of its land under forests. Today we have only about 12 percent. Thus we need not only to protect existing forests but also to increase our forest cover. People who live in or near forests know the value of forest resources first hand because their lives and livelihoods depend directly on these resources. However, the rest of us also derive great benefits from the forests which we are rarely aware of. The water we use depends on the existence of forests on the watersheds around river valleys. Our homes, furniture and paper are made from wood from the forest. We use many medicines that are based on forest produce. And we depend on the oxygen that plants give out and the removal of carbon dioxide we breathe out from the air. Forests once extended over large tracts of our country. People have used forests in our country for thousands of years. As agriculture spread the forests were left in patches which were controlled mostly by tribal people. They hunted animals and gathered plants and lived entirely on forest resources. Deforestation became a major concern in British times when a large amount of timber was extracted for building their ships. This led the British to develop scientific forestry in India. They however alienated local people by creating Reserved and Protected Forests which curtailed access to the resources. This led to a loss of stake in the conservation of the forests which led to a gradual degradation and fragmentation of forests across the length and breadth of the country. Arunodaya University - School of Arts, Humanities and Social Science 48 Another period of overutilisation and forest degradation occurred in the early period following independence as people felt that now that the British had gone they had a right to using our forests in any way we pleased. The following years saw India’s residual forest wealth dwindle sharply. Timber extraction continued to remain the Forest Department’s main concern up to the 1970s. The fact that forest degradation and deforestation was creating a serious loss of the important functions of the forest began to override its utilisation as a source of revenue from timber. India has the second largest concentration of tribal population, after that of African continent. The total schedule tribe population in India, as per 1991 Census, is about 6.78 crores which constitute about 8.08% of total population of 83.86 c

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