EVS Full Note PDF

UNIT 1 INTRODUCTION TO ENVIRONMENTAL STUDIES Environment The word ‗environment‘ is derived from the old French word ‗environer‘ – which means to ‗surround, enclose, and encircle‘. Environment refers to an aggregate of conditions or surroundings in which living beings such as humans, animals,...

UNIT 1 INTRODUCTION TO ENVIRONMENTAL STUDIES Environment The word ‗environment‘ is derived from the old French word ‗environer‘ – which means to ‗surround, enclose, and encircle‘. Environment refers to an aggregate of conditions or surroundings in which living beings such as humans, animals, and plants live or survive and non-living things exist. All living beings including man and their environment are mutually reactive, affecting each other in a number of ways. It is generally equated with nature wherein physical components of the planet earth such as earth, air, water, etc. support and affect life in the biosphere. The term 'environment' is widely used and has a broad range of definitions, meanings and interpretations. What does the term 'environment' mean? In popular usage, for some people, the term 'environment' means, simply, 'nature': in other words, the natural landscape together with all of its non-human features, characteristics and processes. To those people, the environment is often closely related to notions of wilderness and of pristine landscapes that have not been influenced - or, at least, that have been imperceptibly influenced - by human activities. However, for other people, the term 'environment' includes human elements to some extent. In scientific manner environment means interaction of biotic and Abiotic factors present in surrounding. Biotic factors describes a living component of an ecosystem; for example organisms, such as plants and animals. Abiotic factors refer to all the non-living components like physical conditions (temperature, pH, humidity, salinity, sunlight, etc.) and chemical agents (different gases and mineral nutrients present in the air, water, soil, etc.) in an environment. Environmental components The four major components of environment include lithosphere, hydrosphere, atmosphere and biosphere, corresponding to rocks, water, air and life respectively. Lithosphere is the outermost layer of earth called crust, which is made of different minerals. Its depth can reach up to 100 kilometers and is found on both land (terrestrial crust) and oceans (oceanic crust). The main component of lithosphere is earth‘s tectonic plates. Lithosphere refers to the rigid and outermost shell on Earth. The composition of it is the crust and the portion of the upper mantle. We can distinguish the crust and upper and mantle on the basis of chemistry and mineralogy. In other words, it includes the crust and the uppermost mantle that constitutes the hard and rigid outer layer of our planet Earth. The uppermost part of the lithosphere which chemically reacts to the atmosphere, hydrosphere, and biosphere through the soil- forming process is known as the pedosphere. The crust of the earth is not a homogenous substance. In other words, it has got different layers of rocks which include sedimentary rocks on the top, then there are granitic and metamorphic rocks in the middle and finally, at the bottom, there are basaltic rocks. 5 Hydrosphere comprises of all forms of water bodies on earth including oceans, seas, rivers, lakes, ponds, streams etc. It covers 70% of earth‘s surface. 97.5% of water found on Earth is in the oceans in the form of salt water. Only 2.5 % of water on Earth is freshwater. Out of this, 30.8% is available as groundwater and 68.9% is in frozen forms as in glaciers. Amount of 0.3% is available in rivers, reservoirs and lakes and is easily accessible to man. Atmosphere is gaseous layer enveloping the Earth. The atmosphere with oxygen in abundance is unique to Earth and sustains life. It mainly comprises 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, and traces of hydrogen, helium, and noble gases. The amount of water vapor present is variable. Earth‘s atmosphere has five major and several secondary layers. From lowest to highest, the major layers are the troposphere, stratosphere, mesosphere, thermosphere and exosphere. Troposphere- Earth‘s troposphere extends from Earth‘s surface to, on average, about 12 kilometers (7.5 miles) in height, with its height lower at Earth‘s poles and higher at the equator. Yet this very shallow layer is tasked with holding all the air plants need for photosynthesis and animals need to breathe, and also contains about 99 percent of all water vapor and aerosols (minute solid or liquid particles suspended in the atmosphere). In the troposphere, temperatures typically go down the higher you go, since most of the heat found in the troposphere is generated by the transfer of energy from Earth‘s surface. The troposphere is the densest atmospheric layer, compressed by the weight of the rest of the atmosphere above it. Most of Earth‘s weather happens here, and almost all clouds that are generated by weather are found here, with the exception of cumulonimbus thunder clouds, whose tops can rise into the lowest parts of the neighboring stratosphere. Most aviation takes place here, including in the transition region between the troposphere and the stratosphere. 6 Stratosphere- Located between approximately 12 and 50 kilometers (7.5 and 31 miles) above Earth‘s surface, the stratosphere is perhaps best known as home to Earth‘s ozone layer, which protects us from the Sun‘s harmful ultraviolet radiation. Because of that UV radiation, the higher up you go into the stratosphere, the warmer temperatures become. The stratosphere is nearly cloud- and weather-free, but polar stratospheric clouds are sometimes present in its lowest, coldest altitudes. It‘s also the highest part of the atmosphere that jet planes can reach. Mesosphere- Located between about 50 and 80 kilometers (31 and 50 miles) above Earth‘s surface, the mesosphere gets progressively colder with altitude. In fact, the top of this layer is the coldest place found within the Earth system, with an average temperature of about minus 85 degrees Celsius (minus 120 degrees Fahrenheit). The very scarce water vapor present at the top of the mesosphere forms noctilucent clouds, the highest clouds in Earth‘s atmosphere, which can be seen by the naked eye under certain conditions and at certain times of day. Most meteors burn up in this atmospheric layer. Sounding rockets and rocket-powered aircraft can reach the mesosphere. Thermosphere- Located between about 80 and 700 kilometers (50 and 440 miles) above Earth‘s surface is the thermosphere, whose lowest part contains the ionosphere. In this layer, temperatures increase with altitude due to the very low density of molecules found here. It is both cloud- and water vapor-free. The aurora borealis and aurora australis are sometimes seen here. The International Space Station orbits in the thermosphere. Exosphere- Located between about 700 and 10,000 kilometers (440 and 6,200 miles) above Earth‘s surface, the exosphere is the highest layer of Earth‘s atmosphere and, at its top, merges with the solar wind. Molecules found here are of extremely low density, so this layer doesn‘t behave like a gas, and particles here escape into space. While there‘s no weather at all in the exosphere, the aurora borealis and aurora australis are sometimes seen in its lowest part. Most Earth satellites orbit in the exosphere. 7 Biosphere refers to all the regions on Earth where life exists. The ecosystems that support life could be in soil, air, water or land. The term Biosphere was coined by Geologist Edward Suess who used this term for place on Earth where life can be found. Biosphere refers to the sum total of all living matter, the biomass or biota. It extends from the polar ice caps to the equator, with each region harboring some life form suitable to the conditions there. Types of Environment The classification of the environment broadly divides it into two categories – Natural and Manmade environment. Natural Environment Natural environment is the terrestrial environment that is a creation of complex natural and environmental conditions. Although it arose independently of humankind, it is the complement of direct interaction between nature and human society. Natural environment revolves around the subjects of climatology, geology, biogeography, etc. They are direct aspects of how human society conceptualizes the geography of the Earth. Natural environment is also called a geographical environment as it interacts with nature. The earth surface, rivers, mountains, deserts, land, water, oceans, volcanoes, etc. Man-made or artificial Environment Man cannot directly live in the geographical environment, so he creates some of his environmental conditions to adjust to it. This is a man-made or human-made 8 environment, a human creation. A man-made environment is also called a social environment. Multidisciplinary nature of environmental studies Scope and importance Environmental Study is a vast subject to be studied upon. It has all the aspects of various subjects such as anthropology, science, social science, statistics, economics, computers, geology, health, and sociology. It illustrates the multi-sectoral and multi- dimensional study in various fields. It also educates us about the Physical, Social, Cultural, and Biological aspects. It brings our natural environment and human impacts altogether. It is a multidisciplinary approach that deals with every issue that affects an organism. It covers the impacts of environmental science and social aspects of the environment as well. Scope of environmental studies The scope of Multidisciplinary Nature of Environmental Studies consists of various aspects such as biological, cultural, social, and physical. It is also related to other subjects such as science, geography, economics, statistics, health, technology, population, and ecology. Biological aspects – This is one of the most essential aspects of environmental studies. It is the solution of an organism, or a population, or a community to changes in its environment. Human beings, plants, animals, microorganisms, birds, insets are all included in the biological aspects. Cultural aspects – The environment gives knowledge about different customs, laws, dresses, values, and religious beliefs. They all are included under cultural aspects. Environmental studies help us in understanding these diverse aspects. Physical aspects – The environment which is shaped by human activities are considered as physical aspects, for example, bridges, roads, buildings, industries, etc. Apart from them, natural resources such as land, air, water, minerals, vegetation, landforms like hills, oceans, mountains, forests, etc. Social aspects – It illustrates the standard of living, tastes, preferences, educational status, and etiquettes of individuals living in society. Environmental Studies give acquaintance about people who have linguistic, cultural, and educational differences in societies. Importance of environmental studies Environmental Studies is essential as it helps us to understand our surrounding environment and natural phenomena. Numerous points provide us the importance of the Multidisciplinary nature of Environmental Studies. They are: 1. It helps in gaining knowledge about the current environmental issues. It provides us with the necessary skills to obtain solutions for various environmental issues such as pollution, global warming, and climate change. 9 2. It helps in maintaining the ecological balance through fundamental knowledge of environmental systems and processes. 3. It provides us information about the changes in the environment due to anthropogenic factors. It also provides us the skills for analyzing different environmental systems and changes in the environment because of human activities. 4. It aims to preserve and protect biodiversity. It makes us familiar with the various species of flora and fauna. It provides us with different ways to preserve and protect them. 5. It provides us the consciousness about our duties towards the environment. It additionally educates us about the various environmental issues which need to be resolved at a faster pace. Environmental issues such as conservation of energy, toxic emissions, water conservation, proper disposal of wastes, rising global temperature, and many more are also explained to us by environmental studies. 6. Various more issues such as the depletion of natural resources, growing human population, rising numbers of natural calamities, for instance, earthquakes, tsunamis, floods, drought, are all serious concerns that need to be taken seriously. EVS makes us understand the harmful and drastic effects of these issues on the environment, and humans as well. 7. By studying Environmental Studies, people can explore and connect with their natural and surrounding environment. It helps people in developing their insights for understanding human processes, natural phenomena, and various changes in the environment. Concept of sustainability and sustainable development Environment and economy are interdependent and need each other. Hence, development that ignores its repercussions on the environment will destroy the environment that sustains life forms. What is needed is sustainable development: development that will allow all future generations to have a potential average quality of life that is at least as high as that which is being enjoyed by the current generation. The concept of sustainable development was emphasized by the United Nations Conference on Environment and Development (UNCED), which defined it as: ‗Development that meets the need of the present generation without compromising the ability of the future generation to meet their own needs‘. Read the definition again. You will notice that the term ‗need‘ and the phrase ‗future generations‘ in the definition are the catch phrases. The use of the concept ‗needs‘ in the definition is linked to distribution of resources. The seminal report—Our Common Future—that gave the above definition explained sustainable development as ‗meeting the basic needs of all and extending to all the opportunity to satisfy their aspirations for a better life‘. Meeting the needs of all requires redistributing resources and is hence a moral issue. Edward Barbier defined sustainable development as one which is directly concerned with increasing the material standard of living of the poor at the grass root level — this can be quantitatively 10 measured in terms of increased income, real income, educational services, health care, sanitation, water supply etc. In more specific terms, sustainable development aims at decreasing the absolute poverty of the poor by providing lasting and secure livelihoods that minimise resource depletion, environmental degradation, cultural disruption and social instability. Sustainable development is, in this sense, a development that meets the basic needs of all, particularly the poor majority, for employment, food, energy, water, housing, and ensures growth of agriculture, manufacturing, power and services to meet these needs Strategies for sustainable development 1. Use of Non-conventional Sources of Energy India, as you know, is hugely dependent on thermal and hydro power plants to meet its power needs. Both of these have adverse environmental impacts. Thermal power plants emit large quantities of carbon dioxide which is a green house gas. It also produces fly ash which, if not used properly, can cause pollution of water bodies, land and other components of the environment. Hydroelectric projects inundate forests and interfere with the natural flow of water in catchment areas and the river basins. Wind power and solar rays are good examples of conventional. In recent years, some efforts are being taken to tap these energy resources. Collect the details of one such unit set up in your area if any, and discuss in the class. 2. LPG, Gobar Gas in Rural Areas Households in rural areas generally use wood, dung cake or other biomass as fuel. This practice has several adverse implications like deforestation, reduction in green cover, wastage of cattle dung and air pollution. To rectify the situation, subsidised LPG is being provided. In addition, gobar gas plants are being provided through easy loans and subsidy. As far as liquefied petroleum gas (LPG) is concerned, it is a clean fuel — it reduces household pollution to a large extent. Also, energy wastage is minimised. For the gobar gas plant to function, cattle dung is fed to the plant and gas is produced which is used as fuel while the slurry which is left over is a very good organic fertiliser and soil conditioner. 3.CNG in Urban Areas: In Delhi, the use of Compressed Natural Gas (CNG) as fuel in public transport system has significantly lowered air pollution and the air has become cleaner. In the last few years many other Indian cities also began to use CNG. 4. Wind Power In areas where speed of wind is usually high, wind mills can provide electricity without any adverse impact on the environment. Wind turbines move with the wind and electricity is generated. No doubt, the initial cost is high. But the benefits are such that the high cost gets easily absorbed. 5. Solar Power through Photovoltaic Cells India is naturally endowed with a large quantity of solar energy in the form of sunlight. We use it in different ways. For example, we dry our clothes, grains, other 11 agricultural products as well as various items made for daily use. We also use sunlight to warm ourselves in winter. Plants use solar energy to perform photosynthesis. Now, with the help of photovoltaic cells, solar energy can be converted into electricity. These cells use special kind of materials to capture solar energy and then convert the energy into electricity. 6. Bio composting In our quest to increase agricultural production during the last five decades or so, we almost totally neglected the use of compost and completely switched over to chemical fertilizers. The result is that large tracts of productive land have been adversely affected, water bodies including ground water system have suffered due to chemical contamination and demand for irrigation has been going up year after year. Farmers, in large numbers all over the country, have again started using compost made from organic wastes of different types. In certain parts of the country, cattle are maintained only because they produce dung which is an important fertiliser and soil conditioner. Earthworms can convert organic matter into compost faster than the normal composting process. This process is now being widely used. Indirectly, the civic authorities are benefited too as they have to dispose reduced quantity of waste. Conclusion- Economic development, which aimed at increasing the production of goods and services to meet the needs of a rising population, puts greater pressure on the environment. In the initial stages of development, the demand for environmental resources was less than that of supply. Now the world is faced with increased demand for environmental resources but their supply is limited due to overuse and misuse. Sustainable development aims at promoting the kind of development that minimises environmental problems and meets the needs of the present generation without compromising the ability of the future generation to meet their own needs. 12  UNIT 2 ECOSYSTEM Ecosystem, the complex of living organisms, their physical environment, and all their interrelationships in a particular unit of space. An ecosystem can be visualized as a functional unit of nature, where living organisms interact among themselves and also with the surrounding physical environment. Ecosystem varies greatly in size from a small pond to a large forest or a sea. Many ecologists regard the entire biosphere as a global ecosystem, as a composite of all local ecosystems on Earth. Classification of Ecosystem Aquatic Ecosystem An ecosystem which is located in a body of water is known as an aquatic ecosystem. The nature and characteristics of the communities of living or biotic organisms and non-living or abiotic factors which interact with and interrelate to one another are determined by the aquatic surroundings of their environment they are dependent upon. Aquatic ecosystem can be broadly classified into Marine Ecosystem and Freshwater Ecosystem. Marine Ecosystem These ecosystems are the biggest of all ecosystems as all oceans and their parts are included in them. They contain salt marshes, intertidal zones, estuaries, lagoons, mangroves, coral reefs, the deep sea, and the sea floor. Marine ecosystem has a unique flora and fauna, and supports a vast kingdom of species. These ecosystems are essential for the overall health of both marine and terrestrial environments. Salt marshes, sea grass meadows, and mangrove forests are among the most productive ecosystem. Coral reef provides food and shelter to the highest number of marine inhabitants in the world. Marine ecosystem has a large biodiversity. 13 Freshwater Ecosystem Freshwater ecosystem includes lakes, rivers, streams, and ponds. Lakes are large bodies of freshwater surrounded by land. Plants and algae are important to freshwater ecosystem because they provide oxygen through photosynthesis and food for animals in this ecosystem. Estuaries house plant life with the unique adaptation of being able to survive in fresh and salty environments. Mangroves and pickle weed are examples of estuarine plants. Many animals live in freshwater ecosystem. Freshwater ecosystem is very important for people as they provide them water for drinking, energy and transportation, recreation, etc. Terrestrial Ecosystem Terrestrial ecosystems are those ecosystems that exist on land. Water may be present in a terrestrial ecosystem but these ecosystems are primarily situated on land. These ecosystems are of different types such as forest ecosystem, desert ecosystem, grassland and mountain ecosystems. Terrestrial ecosystems are distinguished from aquatic ecosystems by the lower availability of water and the consequent importance of water as a limiting factor. These are characterized by greater temperature fluctuations on both diurnal and seasonal basis, than in aquatic ecosystems in similar climates. Availability of light is greater in terrestrial ecosystems than in aquatic ecosystems because the atmosphere is more transparent on land than in water. Differences in temperature and light in terrestrial ecosystems reflect a completely different flora and fauna. Structure of ecosystem The structure of an ecosystem is basically a description of the organisms and physical features of environment including the amount and distribution of nutrients in a particular habitat. It also provides information regarding the range of climatic conditions prevailing in the area. From the structure point of view, all ecosystems consist of the following basic components: 1. Biotic components 2. Abiotic components 1. Biotic Components: The biotic components include all living organisms present in the environmental system. The Biotic components of an ecosystem can be described under the following three heads: 1. Producers (Autotrophic components), 2. Consumers, and 3. Decomposers or reducers and transformers 14 Producers (Autotrophic elements): The producers are the autotrophic elements—chiefly green plants. They use radiant energy of sun in photosynthetic process whereby carbon dioxide is assimilated and the light energy is converted into chemical energy. The chemical energy is actually locked up in the energy rich carbon compounds. Oxygen is evolved as by-product in the photosynthesis. This is used in respiration by all living things. Algae and other hydrophytes of a pond, grasses of the field, and trees of the forests are examples of producers. Chemosynthetic bacteria and carotenoid bearing purple bacteria that also assimilate CO2 with the energy of sunlight but only in the presence of organic compounds also belong to this category. Consumers: Those living members of ecosystem which consume the food synthesized by producers are called consumers. Under this category are included all kinds of animals that are found in an ecosystem. There are different classes or categories of consumers, such as: (a) Consumers of the first order or primary consumers, (b) Consumers of the second order or secondary consumers, (c) Consumers of the third order or tertiary consumers, and (d) Parasites, scavengers and saprobes. (a) Primary consumers: These are purely herbivorous animals that are dependent for their food on producers or green plants. Insects, rodents, rabbit, deer, cow, buffalo, goat are some of the common herbivores in the terrestrial ecosystem, and small crustaceans, molluscs, etc. in the aquatic habitat. (b) Secondary consumers: These are carnivores and omnivores. Carnivores are flesh eating animals and the omnivores are the animals that are adapted to consume herbivores as well as plants as their food. Examples of secondary consumers are sparrow, crow, fox, wolves, dogs, cats, snakes, etc. (c) Tertiary consumers: These are the top carnivores which prey upon other carnivores, omnivores and herbivores. Lions, tigers, hawk, vulture, etc. are considered as tertiary or top consumers. (d) Besides different classes of consumers, the parasites, scavengers and saprobes are also included in the consumers. The parasitic plants and animals utilize the living tissues of different plants and animals. The scavengers and saprobes utilize dead remains of animals and plants as their food. Decomposers and transformers: Decomposers and transformers are the living components of the ecosystem and they are fungi and bacteria. Decomposers attack the dead remains of producers and consumers and degrade the complex organic substances into simpler compounds. 15 The simple organic matters are then attacked by another kind of bacteria, the transformers which change these organic compounds into the inorganic forms that are suitable for reuse by producers or green plants. The decomposers and transformers play very important role in maintaining the dynamic nature of ecosystems. 2. Abiotic Components: Ecological relationships are manifested in physicochemical environment. Abiotic component of ecosystem includes basic inorganic elements and compounds, such as soil, water, oxygen, calcium carbonates, phosphates and a variety of organic compounds (by-products of organic activities or death). It also includes such physical factors and ingredients as moisture, wind currents and solar radiation. Radiant energy of sun is the only significant energy source for any ecosystem. The amount of non-living components, such as carbon, phosphorus, nitrogen, etc. that are present at any given time is known as standing state or standing quantity. Functions of ecosystem 1. Food circulation in the ecosystem Food chain Food chain is a linear sequence of organisms which starts from producer organisms and ends with decomposer species. Food web is a connection of multiple food chains. Food chain follows a single path whereas food web follows multiple paths. From the food chain, we get to know how organisms are connected with each other. Food chain and food web form an integral part of the ecosystem. A food chain shows a single pathway from the producers to the consumers and how the energy flows in this pathway. In the animal kingdom, food travels around different levels. To understand a food chain better, let us take a look at the terrestrial ecosystem. Example for Food chain in Ecosystem The sun is the source of energy, which is the initial energy source. This is used by the producers or plants to create their own food, through photosynthesis and grow. Next in this chain is another organism, which is the consumer that eats this food, taking up that energy. The primary consumers are the organisms that consume the primary producers. In a terrestrial ecosystem, it could be a herbivore like a cow or a goat or it could even be a man. When a goat is consumed by man, he becomes the secondary consumer. Producer—– Primary Consumer —– Secondary or territory consumer 16 Food web A food web consists of all the food chains in a single ecosystem. Each living thing in an ecosystem is part of multiple food chains.... All of the interconnected and overlapping food chains in an ecosystem make up a food web. Trophic Levels. Organisms in food webs are grouped into categories called trophic levels. 17 18 Energy flow in Ecosystem Energy has been defined as the capacity to do work. Energy exists in two forms potential and kinetic. Potential energy is the energy at rest {i.e., stored energy) capable of performing work. Kinetic energy is the energy of motion (free energy). It results in work performance at the expense of potential energy. Conversion of potential energy into kinetic energy involves the imparting of motion. The source of energy required by all living organisms is the chemical energy of their food. The chemical energy is obtained by the conversion of the radiant energy of sun. The radiant energy is in the form of electromagnetic waves which are released from the sun during the transmutation of hydrogen to helium. The chemical energy stored in the food of living organisms is converted into potential energy by the arrangement of the constituent atoms of food in a particular manner. In any ecosystem there should be unidirectional flow of energy. Living organisms can use energy in two forms radiant and fixed energy. Radiant energy is in the form of electromagnetic waves, such as light. Fixed energy is potential chemical energy bound in various organic substances which can be broken down in order to release their energy content. Organisms that can fix radiant energy utilizing inorganic substances to produce organic molecules are called autotrophs. Organisms that cannot obtain energy from abiotic source but depend on energy-rich organic molecules synthesized by autotrophs are called heterotrophs. Those which obtain energy from living organisms are called consumers and those which obtain energy from dead organisms are called decomposers 19 When the light energy falls on the green surfaces of plants, a part of it is transformed into chemical energy which is stored in various organic products in the plants. When the herbivores consume plants as food and convert chemical energy accumulated in plant products into kinetic energy, degradation of energy will occur through its conversion into heat. When herbivores are consumed by carnivores of the first order (secondary consumers) further degradation will occur. Similarly, when primary carnivores are consumed by top carnivores, again energy will be degraded. Trophic level: The producers and consumers in ecosystem can be arranged into several feeding groups, each known as trophic level (feeding level). In any ecosystem, producers represent the first trophic level, herbivores present the second trophic level, primary carnivores represent the third trophic level and top carnivores represent the last level. Ecosystem Productivity Productivity refers to the rate of generation of biomass in an ecosystem, usually expressed in units of mass per volume (unit surface) per unit of time, such as grams per square meter per day (g m−2 d−1). Primary productivity: It is defined as the rate of which radiant energy is stored by the producers, most of which are photosynthetic, and to a much lesser extent the chemosynthetic microorganisms. Secondary productivity It is the rate of energy storage at consumer‘s levels-herbivores, carnivores and decomposers. Consumers tend to utilize already produced food materials in their respiration and also converts the food matter to different tissues by an overall process. Biogeochemical Cycle The natural pathway through which essential elements in living matters undergoes circulation is known as a biogeochemical cycle. The natural elements in the biogeochemical cycles flow from abiotic (non-living) components to biotic (living) components. Biogeochemical, as a term, refers to three aspects in each cycle. Those aspects are biological, geological and chemical. Importance of Biogeochemical Cycle Biogeochemical cycles help in the regulation of natural elements that are necessary for living beings, by channelling through physical and biological phenomenon. It acts as a recycling procedure in nature. Types of Biogeochemical Cycles Water cycle Water cycle relates to the movement through various stages such as – Evaporation Condensation Precipitation 20 Infiltration Run-off Water is indispensable for life‘s existence, and ocean plays a vital role in the cycle. Atmospheric water vapour causes precipitation for which evaporation from water surface is critical. Water cycle also plays a critical role in weather, pressure and temperature in environment. Carbon cycle Carbon moves from atmosphere to living organisms and back again to the atmosphere. Plants are taken as the starting point of carbon cycle. The main stages in carbon cycle are – photosynthesis, respiration, combustion and decomposition. Oxygen cycle Oxygen cycle is the movement of oxygen through atmosphere, biosphere and lithosphere. It is released through the process of photolysis. The main steps of the cycle include photosynthesis and respiration and further repetition. Nitrogen cycle Nitrogen is essential for life form owing to its presence in nucleic acids and proteins. Plants absorb nitrogen through microbial transformations. The main steps involved in the cycle – Nitrogen fixation Nitrogen assimilation Ammonification Nitrification De-nitrification Sulphur cycle Sulphur, which is present mainly as a component of amino acid, may be found in soil as proteins. It is eventually absorbed by plants as sulphates, through a host of microbial transformations. The sulphur proteins convert into hydrogen sulphide (H2S) which is further broken down into sulphur in reaction with oxygen. With bacterial action, it becomes sulphate to be absorbed by plants. Phosphorus cycle Phosphorus mainly passes through hydrosphere, lithosphere and biosphere. It is essential for both animal and plant growth. However, it gradually depletes in soil. In comparison to the carbon cycle, the phosphorus cycle does not pass through the atmosphere. Ecological succession Ecological succession is a sequence of changes that occur in an ecological system over time.‖ The gradual and progressive growth of a species in any given area with respect to its changing surroundings is called ecological succession. It is an anticipated change that beholds the biotic components being an inevitable part of them in the environment. Ecological succession aims at reaching the equilibrium in the ecological system. This is achieved by a community called the climax community. To attain this point of 21 equilibrium constant change (increase or decrease) in the number of species is observed. The area in which the order of communities undergoes a specific change is called sere. Each changing community is therefore called a seral community. All communities around us have undergone ecological succession ever since their existence was identified. Evolution thus is a simultaneously occurring process along with ecological succession. Also, the initiation of life on earth can be considered to be a result of this succession process. Any area where life started from scratch by succession is termed to have been gone under a process called primary succession. If on the other hand, if life begins at a place that has lost all its existing life forms then the process is called secondary succession. Primary succession is a gradual and low process because in this case, life starts from nothing. Secondary succession is a faster process because life has already been supported in these conditions earlier. 1. Primary Succession Primary succession is the succession that begins in lifeless areas such as the regions devoid of soil or barren lands where the soil is unable to sustain life. When the planet was first formed there was no soil on earth. The earth was only made up of rocks. These rocks were broken down by microorganisms and eroded to form soil. This is a process called erosion. The soil then becomes the foundation of plant life. These plants help in the persistence of different animals and progress from primary succession to the climax community. If the primary ecosystem is destroyed, secondary succession takes place. 2. Secondary Succession Secondary succession occurs when the primary ecosystem gets wiped out. For e.g., a climax community gets destroyed by fire. It gets recolonized after the devastation. This is known as secondary ecological succession. Small plants emerge first, followed by larger plants. The tall trees block the sunlight and change the structure of the organisms below the canopy. Finally, the climax community comes into action. 3. Cyclic Succession The change in the structure of an ecological system on a cyclic basis is called cyclic succession. There are some plants that stay dormant for most of the year but emerge all at once. This can cause structural variations in the ecosystem. 4. Seral Community ―A seral community is a transitional stage of ecological succession progressing in the direction of the climax community.‖ A seral community is substituted by the succeeding community. It consists of simple food webs and food chains. It exhibits a very low degree of diversity. The individuals are less in number and the nutrients are also less. 22 Causes of Ecological Succession Some important causes may be defined as below: Climatic Causes: these can be rainfall, temperature variations, humidity, gas composition, etc. Biotic Causes: the organisms in a community compete to thrive for existence. Some of them are lost in the process while some new ones are incorporated. External Causes: soil conditions are affected by the process of migration, invasion, and competition amongst various species. Case study of Ecosystem Forest ecosystem A forest ecosystem is a functional unit or a system which comprises of soil, trees, insects, animals, birds, and man as its interacting units. A forest is a large and complex ecosystem and hence has greater species diversity. Also, it is much more stable and resistant to the detrimental changes as compared to the small ecosystems such as wetlands and grasslands. A forest ecosystem, similar to any other ecosystem, also comprises of abiotic and biotic components. Abiotic components refer to inorganic materials like air, water, and soil. Biotic components include producers, consumers, and decomposers. These components interact with each other in an ecosystem and thus, this interaction among them makes it self-sustainable. Structural Features of the Forest Ecosystem The two main structural features of a forest ecosystem are: Species composition: It refers to the identification and enumeration of the plant and animal species of a forest ecosystem. Stratification: It refers to the vertical distribution of different species which occupy different levels in the forest ecosystem. Every organism occupies a place in an ecosystem on the basis of source of nutrition. For example, in a forest ecosystem, trees occupy the top level, shrubs occupy the second and the herbs and grasses occupy the bottom level. Components of a Forest Ecosystem The function of a forest ecosystem are as follows: 1. Productivity The basic requirement for any ecosystem to function and sustain is the constant input of solar energy. Plants are also the producers in a forest ecosystem. There are two types of productivity in a forest ecosystem, primary and secondary. Primary productivity means the rate of capture of solar energy or biomass production per unit area over a period of time by the plants during photosynthesis. It is further divided into Gross Primary Productivity (GPP) and Net Primary Productivity (NPP). GPP of an ecosystem is the rate of capture of solar energy or the total production of biomass. However, plants also use a significant amount of GPP in respiration. Thus, NPP is the amount of biomass left after the utilization by plants or the producers. We can hence say that NPP is the amount which is available for the 23 consumption to herbivores and decomposers. Secondary productivity means the rate of absorption of food energy by the consumers. 2. Decomposition Decomposition is an extremely oxygen-requiring process. In the process of decomposition, decomposers convert the complex organic compounds of detritus into inorganic substances such as carbon dioxide, water and nutrients. Detritus is the remains of the dead plant such as leaves, bark, flowers and also the dead remains of the animals including their faecal matter. The steps involved in the process of decomposition are fragmentation, leaching, catabolism, humification and mineralization. In the process of fragmentation, detritivores break down the detritus into smaller particles. In the process of leaching, water-soluble inorganic nutrients descend down into the soil and settle as unavailable salts. Under the process of catabolism, bacterial and fungal enzymes reduce detritus into simpler inorganic substances. Humification and mineralization processes take place during the decomposition of soil and not detritus. The process of humification leads to the accumulation of humus which undergoes decomposition at a very slow rate. In the process of mineralization, the humus gets further degraded by microbes and inorganic nutrients are released. 3. Energy flow Energy flows in a single direction. Firstly, plants capture solar energy and then, transfer the food to decomposers. Organisms of different trophic levels are connected to each other for food or energy relationship and thus form a food chain. Energy Pyramid is always upright because energy flows from one trophic level to the next trophic level and in this process, some energy is always lost as heat at each step. 4. Nutrient Cycling Nutrient cycling refers to the storage and movement of nutrient elements through the various components of the ecosystem. There are two types of Nutrient cycling, gaseous and sedimentary. For Gaseous cycle (i.e. nitrogen, carbon), atmosphere or hydrosphere is the reservoir whereas for the sedimentary cycle (i.e. phosphorus) Earth‘s crust is the reservoir. Advantage of Forest Ecosystem Forest ecosystem support life on earth. It maintains quality of water and air, the basic essentials of existence of life. Stability in soil is possible by trees, enables the land based plants and animals to live. From their biodiversity grows wealth in the form of food, medicines, essential for human health. It acts as Carbon sinks absorbing Carbon dioxide and keeps global warning at body. Forests influence climate and educe extremes of temperature. They conserve soil and regulate moisture and stream flow. It prevents soil erosion and floods. Forests also supply raw materials to so many industries like pulp-paper, news print, saw milling, matches, and medicinal herbs. It is the source of wood for use in houses construction and fuel wood. Forests help in main export items like teak, paper, paper boards, 24 natural resins, seeds obtained from forests. Forests also source of revenue to the Government in the form of royalty, from leases of forest products. It also provides employment to a large many people. Grass Land Ecosystem Grassland Ecosystem is an area where the vegetation is dominated by grasses and other herbaceous (non-woody) plants. It is also called transitional landscape because grassland ecosystems are dominated by the grass with few or no trees in the area where there is not enough for a forest and too much of a forest. Components of Grassland Ecosystem The components of the Grassland Ecosystem are discussed below: 1. Abiotic Components: These are non-living thing components consist of carbon, hydrogen, sulphur, nitrogen and phosphorous etc. 2. Biotic Components: These are living components and its sub-components are discussed below- (I) Producers: The primary producers of food are the grasses such as Aristida, Cynodon, Digitaria, Desmodium, Setaria etc. If herbs and shrubs are present, they also contribute to the primary production of food. (II) Consumers: The consumers in a grassland ecosystem are of three levels. (a) Primary consumers: These feed directly from the grasses (grazing) and include herbivores such as Cows, Buffaloes, Goats, Rabbits, Mouse etc. and also insects, termites, centipede, millipedes etc. (b) Secondary consumers: These consumers are the carnivorous animals such as snakes, lizard, jackal, foxes, frogs etc. which feed on the primary consumers. (c) Tertiary consumers: Hawk, Eagles and vultures constitute the tertiary consumer in the grassland ecosystem which preys upon the secondary and primary consumer. (III) Decomposers: The organic matter of the grassland is decomposed by the microbes like actinomycetes, fungi (Mucor, Aspergillus, Rhizopus, Penincillium, and Cladosporium), aerobic and anaerobic soil bacteria etc. They release the minerals back into the soil thus making the soil fertile. Functions of the Grassland Ecosystem The primary function of an ecosystem is productivity. The producers fix the solar energy and produce the complex organic matter with the help of minerals. It provides forage for livestock, protection and conservation of soil and water resources, furnishing a habitat for wildlife, both flora and fauna and (contribution to the attractiveness of the landscape. The functional aspects of the Grassland can be studied by two means: 25 1. Food Chain in an ecosystem: There is an important feature of the ecosystem that one level of an organism serves as food for another level of the organism. A series is formed which is known as Food Chain. In an ecosystem, the food chain does not follow the linear pattern, but an organism may feed upon more than one organism in the same food chain or upon organisms of different food chains. Thus interconnected food chain system is formed known as a food web. 2. Nutrient cycle in an ecosystem: For any ecosystem to be successful, it is important that the constituent materials move in a cyclic manner. The producers (green plant) takes up the mineral elements from the soil and air, convert them into organic form and after passing through the different trophic levels, are again returned to the soil and air. Aquatic ecosystem The aquatic ecosystem definition states it is a water-based environment, wherein, living organisms interact with both physical and chemical features of the environment. These living creatures whose food, shelter, reproduction and other essential activities depend in a water-based environment are known as aquatic organisms. Some of the most common aquatic organisms are – nekton, plankton and benthos. Additionally, lakes, oceans, ponds, rivers, swamps, coral reefs, wetlands, etc. are a few popular aquatic ecosystem examples. Marine Water Ecosystem This particular ecosystem is the largest aquatic ecosystem and covers over 70% of the earth‘s total surface. This ecosystem is relatively more concentrated in terms of salinity. Nonetheless, the body of aquatic organisms is well-adjusted to saline water, and they may find it challenging to survive in freshwater. These following categories comprise the marine ecosystem. Ocean Ecosystem Pacific Ocean, Atlantic Ocean, Indian Ocean, Arctic Ocean and the Southern Ocean are the five major oceans on earth. Notably, the Pacific Ocean is the largest and deepest of these five, while Atlantic is the second largest in terms of size. Also, the Southern Ocean harbors the largest population of Krill among them. Other than that, the oceans serve as home to aquatic organisms like – turtles, crustaceans, plankton, corals, shellfish, blue whale, shark, tube worms, reptiles, etc.. Estuaries Typically, it is the meeting point of a sea and rivers, which makes the water slightly more saline when compared to freshwater and more diluted when compared to the marine ecosystem. 26 Biologically, estuaries are considered to be productive as it stimulate primary production and trap plant nutrients. Some examples of estuaries include – tidal marshes, river mouth, and coastal bay. Freshwater Ecosystem This aquatic ecosystem covers less than 1% of the earth‘s surface and is broadly divided into – wetlands, lentic and lotic ecosystems. Swamps and Wetlands These are marshy areas which are often covered in water and harbour a variety of flora and fauna. Wetlands are known to be a home of water lilies, marshes, swamps, Northern Pikes, dragonflies, Green Heron, etc. Lentic Ecosystems It includes standing water bodies like ponds and lakes and is a home to both floating and rooted plants, algae and invertebrates. Salamander, frogs, water snakes and alligators are commonly found in lentic ecosystems. Lotic Ecosystems These aquatic ecosystems are characterised by rapid flowing water moving in one direction. They are a hub of a wide variety of insects like beetles, mayflies and stoneflies, among others. Also, it harbours species like river dolphins, beavers, otters, eel, minnow and trout. Functions of Aquatic Ecosystem Facilitates recycling of nutrients Helps to purify water Recharges groundwater Is a habitat for aquatic flora and flora Mitigates flood Desert Ecosystem Earth is the only planet where life is possible and comprises of an atmosphere, ecosystem and various land formations that are necessary for the survival. Earth is 70% covered by water and remaining part is covered by land. 1/5th of the earth‘s land is covered with deserts. Every continent on this earth has a desert and every desert has its own ecosystem which is known as Desert ecosystem. When we hear the word ‗desert‘ the very first thing that strikes our minds is a big barren, abandoned and dry land without plants covered with sand. A desert can be hot and cold both. Desert is one of the most dried land areas on this planet that receives very little precipitation annually. It is a land with very less rainfall throughout the year measured less than 50 cm a year. Structure and Function: The different components of a desert ecosystem are: (A) Abiotic Component 27 The abiotic component includes the nutrients present in the soil and the aerial environment. The characteristic feature of the abiotic component is lack of or-ganic matter in the soil and scarcity of water. (B) Biotic Component The various biotic components representing three functional groups are: (a) Producer organisms The producers are mainly shrubs or bushes, some grasses and a few trees. Surprisingly, there are many species of plants that survive in the desert. Most of them are succulents, which mean they store water. Others have seeds that lay dormant until a rain awakens them. Regardless, these plants find a way to get water and protect themselves from the heat. (b) Consumers These include animals such as insects and reptiles. Besides them, some rodents, birds and some mammalian vertebrates are also found. Desert mammals, Desert Birds, Desert Reptiles, Desert Insects and Arachnids. (c) Decomposers Due to poor vegetation the amount of dead organic matter is very less. As a result the decomposers are very few. The common decomposers are some bacte-ria and fungi, most of which are thermophile. 28  UNIT 3: NATURAL RESOURCES: RENEWABLE AND NON- RENEWABLE RESOURCES Natural resources are naturally occurring materials that are useful to man or could be useful under conceivable technological, economic or social circumstances or supplies drawn from the earth, supplies such as food, building and clothing materials, fertilizers, metals, water and geothermal power. Based on the availability are two types of natural resources: Renewable: resources that are available in infinite quantity and can be used repeatedly are called renewable resources. Example: Forest, wind, water, etc. Non-Renewable: resources that are limited in abundance due to their non- renewable nature and whose availability may run out in the future are called non- renewable resources. Examples include fossil fuels, minerals, etc. A renewable resource is one that can be used repeatedly and does not run out because it is naturally replaced. Examples of renewable resources include solar, wind, hydro, geothermal, and biomass energy. Energy resources Energy resources are all forms of fuels used in the modern world, either for heating, generation of electrical energy, or for other forms of energy conversion processes. Energy resources can be roughly classified in three categories: renewable, fossil, and nuclear. Fossil energy resources are obtained from dead plant and animal deposits created over the long history of the planet. These resources are vast, but limited, and are not renewable. Until recently fossil fuels have provided for the majority of humanity‘s energy demands. These resources mainly include coal, oil, and natural gas. Energy crises in India The energy crisis is the concern that the world‘s demands on the limited natural resources that are used to power industrial society are diminishing as the demand rises. These natural resources are in limited supply. While they do occur naturally, it can take hundreds of thousands of years to replenish the stores. Governments and concerned individuals are working together to make the use of renewable resources a priority and to lessen the irresponsible use of natural supplies through increased conservation. Causes 1. Overconsumption The energy crisis is a result of many different strains on our natural resources, not just one. There is a strain on fossil fuels such as oil, gas, and coal due to overconsumption – which then, in turn, can put a strain on our water and oxygen resources by causing pollution. 29 2. Overpopulation Another cause of the crisis has been a steady increase in the world‘s population and its demands for fuel and products. No matter what type of food or products you choose to use – from fair trade and organic to those made from petroleum products in a sweatshop – not one of them is made or transported without a significant drain on our energy resources. 3. Poor Infrastructure Aging infrastructure of power generating equipment is yet another reason for energy shortage. Most of the energy-producing firms keep on using outdated equipment that restricts the production of energy. It is the responsibility of utilities to keep on upgrading the infrastructure and set a high standard of performance. 4. Unexplored Renewable Energy Options Renewable energy still remains unused in most of the countries. Most of the energy comes from non-renewable sources like coal. It, therefore, remains the top choice to produce energy. Unless we give renewable energy a serious thought, the problem of energy crisis cannot be solved. Renewable energy sources can reduce our dependence on fossil fuels and also helps to reduce greenhouse gas emissions. 5. Delay in Commissioning of Power Plants In a few countries, there is a significant delay in the commissioning of new power plants that can fill the gap between demand and supply of energy. The result is that old plants come under huge stress to meet the daily demand for power. When supply doesn‘t match demand, it results in load-shedding and breakdown. 6. Wastage of Energy In most parts of the world, people do not realize the importance of conserving energy. It is only limited to books, the internet, newspaper ads, lip service, and seminars. Unless we give it a serious thought, things are not going to change anytime sooner. Land resources- Land degradation The term ―land resources‖ encompasses the physical, biotic, environmental, infrastructural and socio-economic components of a natural land unit, including surface and near-surface freshwater resources important for management. The interaction between the components of land resources is vital for determining the productivity and sustainability of agro-ecosystems. Land use change is a process by which human activities transform the natural landscape, referring to how land has been used, usually emphasizing the functional role of land for economic activities. Land use changes are often nonlinear and might trigger feedbacks to the system, stress living conditions, and threaten people with vulnerability. 30 Land degradation- Land degradation is a process in which the value of the biophysical environment is affected by a combination of human-induced processes acting upon the land. It is viewed as any change or disturbance to the land perceived to be deleterious or undesirable. Natural hazards are excluded as a cause; however human activities can indirectly affect phenomena such as floods and bush fires. Causes of land degradation- 1. Deforestation: Forests play an important role in maintaining fertility of soil by shedding their leaves which contain many nutrients. Forests are also helpful in binding up of soil particles with the help of roots of vegetation. Therefore, cutting о forests will affect the soil adversely. 2. Excessive Use of Fertilizers and Pesticides: Fertilizers are indispensable for increasing food production but their excessive use has occasioned much concern as a possible environmental threat. Excessive use of fertilizers is causing an imbalance in the quantity of certain nutrients in the soil. This imbalance adversely affects the vegetation. 3. Overgrazing: Increase in livestock population results in overexploitation of pastures. Due to this, grass and other types of vegetation are unable to survive and grow in the area, and lack of vegetation cover leads to soil erosion. Millions of people in Africa and Asia raise animals on pastures and rangelands that have low carrying capacity because of poor quality or unreliable rainfall Pastoralists and their rangelands are threatened by overgrazing. 4. Salination: Increase in the concentration of soluble salts in the soil is called salination. India has about six million hectares of saline land. 5. Water-logging: Excessive irrigation and improper drainage facility in the fields cause rise in the ground water level. This ground water mixes with surface water used for irrigation and creates a situation called water-logging. Ground water brings the salts of soil in dissolved state up to the surface where they form a layer or sheet of salt after evaporation. The term salinity is used for such a situation. 6. Desertification: Desertification is a widespread process of land degradation in arid, semi- arid, and dry sub-humid areas resulting from various factors, including climatic variations and human activities. 7. Soil erosion: Accelerated soil erosion by water and wind is the major land degradation process and this is a consequence of changed relationship between environmental factors 31 which occur as a result of human interventions. Adverse changes in physical, chemical or biological characteristics of the soil result in reduced fertility and soil erosion. 8. Wasteland: Wastelands are the lands which are economically unproductive, ecologically unsuitable and subject to environmental deterioration. 9. Landslides: The sudden movement of the soil and the weathered rock material down the slope due to the force of gravity is called a landslide. Lad-slides are common in mountainous regions especially those which are situated along the river banks or near the coastline. Control measures of land degradation 1. Afforestation and proper management of grazing land. 2. Control on mining activities. 3. Sheltering belts are planted for plants. 4. Law and policies 5. Adopt soil conservation method Deforestation Deforestation refers to the decrease in forest areas across the world that are lost for other uses such as agricultural croplands, urbanization, or mining activities. Deforestation causes can either be direct or indirect. Among direct causes are: Natural causes as hurricanes, fires, parasites and floods Human activities as agricultural expansion, cattle breeding, timber extraction, mining, oil extraction, dam construction and infrastructure development. Among indirect causes are: Insufficient political actions and governance failure as inadequate land tenure system, corruption, wrong public administration investments Political and socio-economic causes as population growth, military conflicts and climatic changes 1. Cultivations and livestock farming We should consider, infact, that with regards to the substitution of forest areas with cultivations and livestock farms, the impact is much higher because after the extraction of the most precious trees which are destined for timber commercialization, forests are set on fire causing a great impact on local animals and plants. The most disastrous year for the Amazon forest has been 1991 when over 50,000 fires where registered by aerial views or satellite images. 2. Timber extraction Centuries-old trees are cut down to make timber or cellulose for the furniture or paper industry. Any system employed for wood cutting causes serious damage to the ecosystem, and these damages are amplified by construction of roads required 32 for vehicles and to trasport chopped timber to its destination. For this reason, also many other economically unattractive trees which have an important biological and ecological value are are cut down. 3. Firewood collection This activity is undertaken especially by native populations, which due to recent population growth, must provide energy sources for their survival. This phenomenon adds to large-scale industrial timber exploitation. 4. Road Construction Besides the construction of roads to transport timber, also dam construction and industrial exploitation of mines contribute to massive deforestation. 5. Mining activates 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. 6. Urbanization 7. Industrialization 8. Construction of dams and bridges 9. Human Population growth Construction of Dams Main Purposes of Dams 1. Irrigation The primary and main purpose of constructing a dam is to store water and use it for irrigation. The major irrigation projects, which are dependent on the dam, often help prevent the mitigation of rural people to the cities, while giving them a higher standard of living in their native areas. 2. Hydropower Generation Hydropower is considered the largest renewable energy source of electricity and clean because it does not contribute to global warming, air pollution, acid rain, or ozone depletion. Hydropower generated by the dams is the most plentiful and most efficient renewable energy resource, contributing to 24% of all renewable electric energy produced all over the world. 3. Flood Prevention Flood control is a significant purpose for many of the existing dams and continues as the main purpose for some of the major dams of the world currently under construction. The dams are used to effectively regulate the level of water flowing in the river by temporarily storing the flood volume and releasing it later. Every dam has an integrated water management plan for regulating the storage and discharge of water into the river basin without damage. This plan helps to impound floodwaters and then either release them under control to the river below the dam or store or divert the water for other uses 33 4. Water Supply Dams play an important role in the water supply for domestic and industrial use. Dams store the water and supply it during the shortage of times. 5. Inland Navigation Dams just not only serve as an irrigational lifeline, but also provide inland navigation throughout the heartland of the nation. The advantages of inland navigation, however, when compared with highway and rail are the large load- carrying capacity of each barge, the ability to handle cargo with large-dimensions and fuel savings 6. Recreation Dams provide prime recreational facilities such as boating, skiing, camping, picnic areas, and boat launch facilities are all supported by dams. The large water stored due to the construction of dams facilitates the growth of flora and fauna in the region due to which many recreational activities such as natural history, bird watching, landscape painting, walking, and hiking are on the rise. Water resources Water is a vital elixir for all living beings. Although it is a renewable resource, scarcity of quality water is felt in many parts of the world. We need water to grow food, keep clean, generate electricity, control fire, and last but not the least, we need it to stay alive. World Ocean water covers about 75 percent of the surface of the earth. Therefore, the earth is called the water planet. Ocean water is saline and not fit for human consumption. Fresh water is just about 2.7 percent of the total water. Global warming and perpetuating water pollution have made a considerable part of available freshwater unfit for human consumption. Use of Water Resources Water resources are used for agricultural, industrial, domestic, recreational, and environmental activities. Majority of the uses require fresh water. However, about 97.5 percent of water found on the earth is salt water and only 2.5 percent is fresh water. A little over two-thirds of the available fresh water is frozen in glaciers and polar ice caps. The remaining freshwater is found mainly as groundwater and a negligible portion of it is present on the ground or in the air. Following is a brief account of how water is used in different sectors. Agricultural Use Agriculture accounts for 69 percent of all water consumption basically in agricultural economies like India. Agriculture, therefore, is the largest consumer of the Earth‘s available freshwater. 34 By 2050, the global water demand of agriculture is estimated to increase by a further 19% due to irrigational needs. Expanding irrigation needs are likely to put undue pressure on water storage. It is still inconclusive whether further expansion of irrigation, as well as additional water withdrawals from rivers and groundwater, will be possible in future. Industrial Use Water is the lifeblood of the industry. It is used as a raw material coolant, a solvent, a transport agent, and as a source of energy. Manufacturing industries account for a considerable share in the total industrial water consumption. Besides, paper and allied products, chemicals and primary metals are major industrial users of water. Worldwide, the industry accounts for 19 percent of total consumption. In industrialized countries, however, industries use more than half of the water available for human use. Domestic Use It includes drinking, cleaning, personal hygiene, garden care, cooking, washing of clothes, dishes, vehicles, etc. Since the end of World War II there has been a trend of people moving out of the countryside to the ever-expanding cities. This trend has important implications on our water resources. Government and communities have had to start building large water-supply systems to deliver water to new populations and industries. Of all water consumption in the world, domestic use accounts for about 12 percent. Use for Hydropower Generation Electricity produced from water is hydropower. Hydropower is the leading renewable source of electricity in the world. It accounts for about 16 percent of total electricity generation globally. There are many opportunities for hydropower development throughout the world. Use for Navigation and Recreation Navigable waterways are defined as watercourses that have been or may be used for transport of interstate or foreign commerce. Agricultural and commercial goods are moved on water on a large scale in a number of regions in the world. Water is also used for recreational purposes such as boating, swimming, and sporting activities. These uses affect the quality of water and pollute it. Highest priority should be given to public health and drinking water quality while permitting such activities in reservoirs, lakes, and rivers. Floods & Draughts Floods and droughts are two well-known natural hazards in the world. The former is due to excess in water flow and the latter is due to scarcity of water. The amount of rainfall received by an area varies from one place to another depending on the location of the place. In some places it rains almost throughout the year whereas in other places it might rain for only few days. India records most of its rainfall in the monsoon season. 35 Heavy rains lead to rise in the water level of rivers, seas, and oceans. Water gets accumulated in the coastal areas, which results in floods. Floods bring in extensive damage to crops, domestic animals, property and human life. During floods, many animals get carried away by the force of water and eventually die. On the other hand, droughts set in when a particular region goes without rain for a long period of time. In the meantime, the soil will continuously lose groundwater by the process of evaporation and transpiration. Since this water is not brought back to earth in the form of rains, the soil becomes very dry. The level of water in the ponds and rivers goes down and in some cases water bodies get dried up completely. Ground water becomes scarce and this leads to droughts. In drought conditions, it is very difficult to get food and fodder for the survival. Life gets difficult and many animals perish in such conditions. Frequent floods and droughts are mostly due to climate change and global warming. Various environmental organizations world over are of the view that climate change is a long-term change in weather patterns, either in average weather conditions or in the distribution of extreme weather events Causes of flood Massive Rainfall Drainage systems and the effective infrastructure design aid during heavy rains. They help the drainage of excess water into reservoirs in an easy way. But in cases of heavy rainfall, the systems stop working. Thus flood is caused. Overflowing of the Rivers The people living along the river always have a risk of life from the overflowing of the Rivers. To prevent such a situation, a string of dams are built. However, if these dams are not managed properly, they may cause flooding and huge damage. Collapsed Dams In the event of huge rainfall, the dams built begin to collapse. Thus, causing the flood situation to become even critical for the people living around. Snowmelt At the time of the high melting of snow due to heavy precipitation and other factors, the situation of flooding arises. Adopting sustainable measures for heavy precipitation can help in dealing with the flooding situation. Snowmelt At the time of the high melting of snow due to heavy precipitation and other factors, the situation of flooding arises. Adopting sustainable measures for heavy precipitation can help in dealing with the flooding situation. Deforestation The cutting of trees in a reckless manner i.e. deforestation is also a major cause of man-made flooding. Trees prevent soil erosion and also the loss of crops. The vegetation is also enriched as a result of more and more trees. This also blocks the massive flow of rain, thus preventing flooding. 36 Climate change The climatic changes caused due to human practices also add to the risk of flooding. Human beings cut trees in a large number, thus affecting the process of photosynthesis. Thus increased level of carbon-di-oxide in the atmosphere cause changes in climate posing threats of natural disasters like floods etc. Emission of Greenhouse Gases The burning of fossil fuels, the industrial influences, the pollution all is depleting the level of the ozone layer and increasing the level of greenhouse gases, becoming a major cause of man-made flooding. Energy Resources Our energy resources include petroleum and petroleum products, coal, uranium (nuclear reactions), and geothermal resources. At present, about 90 percent of the energy needs of the United States are supplied by coal, oil, and natural gas. Petroleum is important also in the production of plastics, asphalt, and thousands of related products. Fossil fuels. Fossil fuels are oil, natural gas, and coal. The general term petroleum includes both natural gas and crude oil. Crude oil is a liquid containing hydrocarbons (molecules made from only hydrogen and carbon) that forms in organic‐ or fossil‐rich sediments and rocks. The hydrogen and carbon in the oil comes from the breakdown of the organic material over time. Natural gas is a gas that contains hydrocarbons and that usually occurs with crude oil. Petroleum forms in marine sedimentary rocks that contain abundant organic remains from microscopic organisms such as algae. Continental shelves contain basins that capture thick accumulations of organic debris. This material lithifies into a source rock that is buried by overlying sediments, and the resulting increased pressure and temperature conditions convert the organic material into hydrocarbons. In response to the confining pressure, petroleum moves outward and upward along zones of increased permeability into a reservoir rock. Reservoir rock, such as sandstone or limestone, has the high porosity and permeability necessary to hold large accumulations of petroleum. The petroleum migrates into a trap (either structural or stratigraphic) in the reservoir rock. Structural traps include faults between permeable and impermeable rocks, thrust faults, and folds such as anticlines. For example, petroleum will collect in a porous limestone reef below the contact with an overlying, impermeable unit such as shale, forming a pocket. A salt dome results when a bed of rock salt is under pressure; the salt extends upward plastically through a sedimentary sequence, disrupting the sediments and creating open spaces that trap petroleum. Stratigraphic traps are naturally occurring changes 37 in a sedimentary sequence that trap migrating oil and gas, such as a porous reef structure in a limestone unit. A sandstone unit surrounded by shale is another stratigraphic trap. The occurrence of oil pools in a number of traps in one area is called an oil field. Crude oil and gas are recovered from oil fields through a series of drilled wells. The petroleum may rise to the surface through the well as a result of its high confining pressure, or it may need to be pumped. Also, water or steam can be pumped into the oil pool from the surface to increase the pressure on the oil and its viscosity. The oil is shipped to a refinery and separated into natural gas, gasoline, kerosene, other oils, and asphalt. A huge variety of petrochemicals produced from petroleum are used in nearly every manufactured product we depend on today, including plastics and synthetic rubber. As the more easily discovered oil fields are pumped dry, oil companies have moved offshore to undertake risky and high‐cost exploration drilling along continental shelves across the world. With only about 5 percent of the world's population, the United States annually consumes over a quarter of the world's total oil production. At present, the United States has only a twenty‐five‐year supply of oil remaining and imports nearly half of the oil it uses. Similarly, natural gas reserves in the United States are expected to be depleted within thirty‐five years. Future sources for natural gas will include gas trapped in coal beds. Oil sands (tar sands) are sandstone deposits that have been cemented with tar or asphalt (blackish, solidified residues from petroleum). Famous deposits include those of the La Brea Tar Pits in Los Angeles, California, and the Athabasca Oil Sand in Alberta, Canada. Oil sands are strip‐mined and processed. Venezuela also has large reserves of oil sand. Heavy crude is a dense, viscous petroleum that flows so slowly it is usually left behind in an oil field. Efforts are continuing to extract this material, including pumping in steam or other solvents to make the crude less viscous. Oil shales are organic‐rich shale formations from which oil can be extracted. The shale formed from muds on the bottom of large shallow lakes. Oil shales tend to be low‐grade and difficult and costly to mine. New technologies are being used to explore ways to extract the oil from the rock in place, including heating the rock with microwaves to separate the oil. The United States has large oil shale resources in Montana, Utah, Colorado, and Wyoming, but at present they are not feasible to mine. Oil shales will ultimately be exploited when the cost of finding new oil fields gets too high. 38 Coal is a dark‐colored sedimentary rock that contains a high percentage of organic plant material. Coal is representative of warm, lush, swampy environments and usually contains abundant plant fossils. Different kinds of coal result from different degrees of compaction and depth of burial. Peat is unlithified organic material that is solid enough to be cut into blocks and burned for fuel. Burial and increasing pressure and temperature convert peat into a soft, brown coal called lignite. Continued pressure results in subbituminous coal and bituminous coal, which are soft, black, banded, and sooty. Metamorphism converts these varieties of coal into anthracite, a hard, black, shiny form of coal that is dust free. Coal beds, or seams, range in thickness from a few centimeters to nearly 30 meters. Coal is mined using underground, open‐pit, and strip‐mine methods. The United States has an impressive coal resource of nearly four trillion tons and consumes or exports about a billion tons a year. Most of the coal in the United States is produced in Kentucky, West Virginia, and Pennsylvania. Coal once provided nearly all of the United States' energy needs. That figure has dropped to less than 25 percent because of the abundance of petroleum, oil, and natural gas and the negative environmental effects of burning coal. Coal is an important ingredient in manufacturing steel. Oil and gas can also be produced from coal. New, cleaner ways of using coal are being researched as the country's petroleum reserves are being depleted. Uranium and geothermal sources. Uranium is used to generate nuclear power. It is found in the minerals pitchblende and carnotite, which are mined from sandstone deposits in the western United States and Canada. Lower‐grade uranium also occurs in organic black shales and phosphate deposits. Nuclear generators are used to produce electricity. Nuclear power supplies about 8 percent of the United States' energy needs. Geothermal sources can also generate electricity but represent less than 1 percent of the energy consumption in the United States. More geothermal power may be used in the future, especially if deeper heat sources across the nation can be located and exploited. 39  UNIT 4: BIODIVERSITY AND CONSERVATION The term biodiversity (from ―biological diversity‖) refers to the variety of life on Earth at all its levels, from genes to ecosystems, and can encompass the evolutionary, ecological, and cultural processes that sustain life. Biodiversity includes not only species we consider rare, threatened, or endangered but also every living thing—from humans to organisms we know little about, such as microbes, fungi, and invertebrates. At the Center for Biodiversity and Conservation, we include humans and human cultural diversity as a part of biodiversity. We use the term ―biocultural‖ to describe the dynamic, continually evolving and interconnected nature of people and place, and the notion that social and biological dimensions are interrelated. This concept recognizes that human use, knowledge, and beliefs influence, and in turn are influenced, by the ecological systems of which human communities are a part. This relationship makes all of biodiversity, including the species, land and seascapes, and the cultural links to the places where we live—be right where we are or in distant lands—important to our wellbeing as they all play a role in maintaining a diverse and healthy planet. Levels of Biodiversity Biodiversity is wide-ranging and is normally divided into three types or levels: 1. Genetic Diversity 2. Species Diversity 3. Ecological Diversity 1. Genetic Diversity All species on Earth are somewhat related through genetic connections. And the more closer a species is related to another, the more genetic information the two species will share. These species will also look more similar. The closest relations of an organism are members of its own species. Members of a species share genes. Genes are the bits of biochemical information that partly determine how an organism looks, behaves, and lives. Moreover, members of a species share intricate mating behaviors. These behaviors help them to identify each other as potential partners. Virtually every species in an environment has a similar and closely related species in a neighboring environment 2. Species Diversity A wide variety of species exists in an environment. And that‘s what is referred to as species diversity. Species are the standard measure of biological diversity in light of the fact that they are the basic units of biological classification. The number of various species in a given ecosystem or environment is described as Species Richness. The total number of species in the world is about 10 million. However, only 1.75 million species have been named scientifically to date. 40 3. Ecological Diversity Ecological or ecosystem diversity is the variety of ecosystems in an area. It involves the complex network of various species present in the ecosystems and the dynamic interactions between them. An ecosystem is made up of organisms from several different species living together in an environment and their connections through the flow of nutrients, energy, and matter. Importance of Biodiversity Biodiversity is important to humans for many reasons. Biodiversity is also considered by many to have intrinsic value—that is, each species has a value and a right to exist, whether or not it is known to have value to humans. 1. Economic—biodiversity provides humans with raw materials for consumption and production. Many livelihoods, such as those of farmers, fishers and timber workers, are dependent on biodiversity. 2. Ecological life support—biodiversity provides functioning ecosystems that supply oxygen, clean air and water, pollination of plants, pest control, wastewater treatment and many ecosystem services. 3. Recreation—many recreational pursuits rely on our unique biodiversity, such as bird watching, hiking, camping and fishing. Our tourism industry also depends on biodiversity. 4. Cultural—the culture is closely connected to biodiversity through the expression of identity, through spirituality and through aesthetic appreciation. Indigenous culture has strong connections and obligations to biodiversity arising from spiritual beliefs about animals and plants. 5. Scientific—biodiversity represents a wealth of systematic ecological data that help us to understand the natural world and its origins. Some of the important biodiversity supplies to humankind are: Food crops, livestock, forestry, and fish Medication Wild plant species have been used for medicinal purposes since before the beginning of recorded history. For example, quinine (Used to treat malaria) comes from the bark of the Amazonian tree Cinchona tree; digitalis from the Foxglove plant (chronic heart trouble), and morphine from the Poppy plant (pain relief). Industry fibers for clothing, wood for shelter and warmth. Biodiversity may be a source of energy (such as biomass). Other industrial products are oils, lubricants, perfumes, fragrances, dyes, paper, waxes, rubber, latexes, resins, poisons and cork can all be derived from various plant species. Supplies from animal origin are wool, silk, fur, leather, lubricants, waxes. Animals may also be used as a mode of transportation. Tourism & recreation biodiversity is a source of economical wealth for many areas, such as many parks and forests, where wild nature and animals are a source of 41 beauty and joy for many people. Ecotourism in particular, is a growing outdoor recreational activity Biogeographic zones of India India is a megadiverse country. With only 2.4 per cent of the total land area of the world, the known biological diversity of India contributes 8 per cent to the known global biological diversity. In terms of Biogeography, India has been divided into 10 biogeographic zones as shown in the below table: India has been divided into ten recognizable biogeographic zones as follow Trans-Himalayan Region It constitutes 5.6 per cent of the total geographical area, includes the high altitude, cold and arid mountain areas of Ladakh, Jammu & Kashmir, North Sikkim, Lahaul and Spiti areas of Himachal Pradesh. This zone has sparse alpine steppe vegetation that harbours several endemic species and is a favourable habitat for the biggest populations of wild sheep and goat in the world and other rare fauna that includes Snow Leopard and the migratory Blacknecked Crane (Grus nigricollis). The cold dry desert of this zone represents an extremely fragile ecosystem. Himalayan Zone It constitutes 6.4 per cent of the total geographical area includes some of the highest peaks in the world. The Himalayan zone makes India one of the richest areas in terms of habitats and species. The alpine and sub-alpine forests, grassy meadows and moist mixed deciduous forests provide diverse habitat for endangered species of bovids such as Bharal (Pseudois nayaur), Ibex (Capra ibex), Markhor (Capra falconeri), Himalayan Tahr (Hemitragus jemlabicus), and Takin (Budoreas taxicolor). Other rare and 42 endangered species restricted to this zone include Hangul (Cervus eldi eldi) and Musk Deer (Moschus moschiferus). Indian Desert Zone Indian Desert Zone, constituting 6.6 per cent of the total geographical area, includes the Thar and the Kutch deserts and has large expanses of grassland that supports several endangered species of mammals such as Wolf (Canis lupus), Caracal (Felis caracal), Desert Cat (Felis libyca) and birds of conservation interest viz., Houbara Bustard (Chamydotis undulate) and the Great Indian Bustard (Ardeotis nigriceps). Semi Arid Region Semi-arid Region, constituting 16.6 per cent of the total geographical area, is a transition zone between the desert and the dense forests of Western Ghats. Peninsular India has two large regions, which are climatically semi-arid. This semi- arid region also has several artificial and natural lakes and marshy lands. The dominant grass and palatable shrub layer in this zone supports the highest wildlife biomass. The cervid species of Sambar (Cervus unicolor) and Chital (Axis axis) are restricted to the better wooded hills and moister valley areas respectively. The Lion (Leo persica), an endangered carnivore species (restricted to a small area in Gujarat), Caracal (Felis caracal),Jackal (Canis aureus) and Wolf (Canis lupus) are some of the endangered species that are characteristic of this region. Western Ghats Constitutes 4.0 per cent of the total geographical area. It is one of the major tropical evergreen forest regions in India and represents one of the two biodiversity ‗hot spots‘. Western Ghats are home to viable populations of most of the vertebrate species found in peninsular India, besides an endemic faunal element of its own. Significant species endemic to this region include Nilgiri Langur (Presbytis jobni), Lion Tailed Macaque (Macaca silenus), Grizzled Giant Squirrel (Ratufa macroura), Malabar Civet (Viverricula megaspila), Nilgiri Tahr (Hemitragus bylocrius) and Malabar Grey Hornbill (Ocycerous griseus). The Travancore Tortoise (Indotestudo forstem) and Cane turtle (Heosemys silvatica) are two endangered taxa restricted to a small area in central Western Ghats. Deccan Plateau Deccan Plateu is India‘s largest biogeographic region making 42 per cent of the total geographical area. It‘s a semi-arid region that falls in the rain shadow area of the Western Ghats. This bio-geographic zone of peninsular India is by far the most extensive zone, covering India‘s finest forests, particularly in the States of Madhya Pradesh, Maharashtra and Odisha. Majority of the forests are deciduous in nature but there are regions of greater biological diversity in the hill ranges. The zone comprising of deciduous forests, thorn forests and degraded scrubland support diverse wildlife species. Species found in this region are Chital (Axis axis), Sambar (Cervus unicolor), Nilgai (Boselapbus tragocamelus) and Chousingha (Tetracerus quadricornis), Barking deer (Muntiacus muntjak) and Gaur (Antilope cervicapra), Elephant (Elephas maximus) 43 in Bihar-Orissa and Karnataka-Tamil Nadu belts, Wild Buffalo (Bubalus bubalis) in a small area at the junction of Orissa, Madhya Pradesh and Maharashtra and the hard ground Swamp Deer (Cervus duvauceli), now restricted to a single locality in Madhya Pradesh. Gangetic Plain Gangetoc plain constitutes around 10.8 per cent of the total geographical area. The Gangetic plain is topographically homogenous for hundreds of kilometers. The characterstic fauna of this region include Rhino (Rhinoceros unicornis), Elephant (Elephas maximus), Buffalo (Bubalus bubalis), Swamp Deer (Cervus duvauceli), Hog-Deer (Axis porcinus) and Hispid Hare (Carprolagus bispidus). North East Region North East Region constitutes 5.2 per cent of the total geographical area. This region represents the transition zone between the Indian, Indo-Malayan and Indo-Chinese bio-geographical regions as well as being a meeting point of the Himalayan mountains and peninsular India. The North-East is thus the biogeographical ‗gateway‘ for much of India‘s fauna and flora and also a biodiversity hotspot (Eastern Himalaya). Many of the species contributing to this biological diversity are either restricted to the region itself, or to the smaller localized areas of the Khasi Hills. Coastal Region Coastal region constitutes 2.5 per cent of the total geographical area with sandy beaches, mangroves, mud flats, coral reefs and marine angiosperm pastures make them the wealth and health zones of India. The coastline from Gujarat to Sunderbans is estimated to be 5,423 km long. Atotal of 25 islets constitute the Lakshadweep, which are of coral origin, and have a typical reef lagoon system, rich in biodiversity. However, the densely populated Lakshadweep islands virtually have no natural vegetation. Andaman and Nicobar Islands This constitutes 0.3 per cent of the total geographical area are one of the three tropical moist evergreen forests zones in India. The islands house an array of flora and fauna not found elsewhere. These islands are centres of high endemism and contain some of India‘s finest evergreen forests and support a wide diversity of corals. In India, endemic island biodiversity is found only in the Andaman and Nicobar Islands. Some of the endemic fauna of Andaman & Nicobar Islands include Narcondam hornbill, South Andaman krait etc. Biodiversity conservation Conservation is the protection, preservation, management, or restoration of wildlife and natural resources such as forests and water. Through the conservation of biodiversity and the survival of many species and habitats which are threatened due to human activities can be ensured. There is an urgent need, not only to manage and conserve the biotic wealth, but also restore the degraded ecosystems. 44 Humans have been directly or indirectly dependent on biodiversity for sustenance to a Considerable extent. However, increasing population pressure and developmental activities have led to large scale depletion of the natural resources. Conservation is the protection, preservation, management, or restoration of wildlife and natural resources such as forests and water. Through the conservation of biodiversity and the survival of many species and habitats which are threatened due to human activities can be ensured. There is an urgent need, not only to manage and conserve the biotic wealth, but also restore the degraded ecosystems. Types of Conservation: Conservation can broadly be divided into two types: 1. In-situ conservation 2. Ex-situ conservation In-situ Conservation: In-situ conservation is on site conservation or the conservation of genetic resources in natural populations of plant or animal species, such as forest genetic resources in natural populations of tree species. It is the process of protecting an endangered plant or animal species in its natural habitat, either by protecting or cleaning up the habitat itself, or by defending the species from predators. It is applied to conservation of agricultural biodiversity in agro forestry by farmers, especially those using unconventional farming practices. In-situ conservation is being done by declaring area as protected area. 1. National parks A national park is an area which is strictly reserved for the betterment of the wildlife and where activities like forestry, grazing on cultivation are not permitted. In these parks, even private ownership rights are not allowed. 2. Wildlife Sanctuaries: A sanctuary is a protected area which is reserved for the conservation of only animals and human activities like harvesting of timber, collecting minor forest products and private ownership rights are allowed as long as they do not interfere with well-being of animals. Boundaries of sanctuaries are not well defined and controlled biotic interference is permitted, e.g., tourist activity. 3. Biosphere reserve it is a special category of protected areas where human population also forms a part of the system. They are large protected area of usually more than 5000 sq.km. Ex-situ conservation Ex situ conservation is the technique of conservation of all levels of biological diversity outside their natural habitats through different techniques like zoo, captive breeding, aquarium, botanical garden, and gene bank. Ex situ conservation is the conservation of areas outside their natural habitat. Botanical gardens, zoological parks, seed banks, cryopreservation, field gene banks, etc. are examples of it. Both native and domesticated animals are well protected and collected in botanic gardens, zoological parks, wildlife safari parks, arboretums, etc. Most of these have catch breeding programs designed to restore the decreasing 45 number of animals and to help the survival of the species. Gene banks are institutions that stock viable seeds (seed banks), live plants (orchards), tissue culture and frozen germ plasm with all genetic viability. There are two types of biodiversity conservation; Ex Situ conservation and In Situ conservation. In situ conservation is the conservation of living resources by maintaining them in their natural ecosystem in which they occur. Examples; national parks, sanctuaries, natural reserves, reserves of the biosphere, sacred grooves, etc. Wild life Sanctuaries in India 1. Corbett National Park in Uttarakhand. 2. Periyar Wildlife Sanctuary in Kerala. 3. Sundarbans National Park in West Bengal. 4. Kaziranga National Park in Assam. 5. Ranthambore National Park in Rajasthan. 6. Kanha National Park in Madhya Pradesh. 7. Bandipur National Park in Karnataka. 8. Bandhavgarh National Park in Madhya Pradesh 9. Sariska National Park, Rajasthan 10. Govind Wildlife Sanctuary in Uttarakhand 11. Nagarhole National Park, Karnataka 12. Bhadra Wildlife Sanctuary, Karnataka 13. Silent Valley National Park, Kerala 14. Panna National Park, Madhya Pradesh 15.Dudhwa National Park, Uttar Pradesh 16. Gir National Park and Sasan Gir Sanctuary, Gujarat 17. Manas National Park, Assam Threats to Biodiversity 1. Habitat Fragmentation Ecosystem conversion and ecosystem degradation contribute to habitat fragmentation. Habitat loss from exploitation of resources, agricultural conversion, and urbanization is the largest factor contributing to the loss of biodiversity. The consequent fragmentation of habitat results in small isolated patches of land that cannot maintain populations of species into the future. Tweedsmuir Provincial Park, at 974,046 hectares, is British Columbia‘s largest provincial park and is big enough to maintain much of the composition, structure and function of biodiversity within the protected area. However, smaller provincial parks, such as Buccaneer Bay at less than one hectare in size, will not be able to maintain all of its original biodiversity in isolation. Scientists report that the effect of habitat fragmentation on biodiversity may not be fully realized for decades after habitat is degraded. Therefore, habitat connectivity must be considered in current management practices to prevent the devastating effects of fragmentation on biodiversity. 46 2. Exotic Species Introductions Infestation by alien species, such as the Codling Moth, is also a major threat to BC ecosystems. The intentional and inadvertent introductions of a wide variety of species to ecosystems in which they do not belong have resulted in ecosystems that differ radically in structure and function from those originally present. Exotic species are typically introduced into ecosystems without their co-evolved predators and parasites, which enables an alien invader to out-compete native species with similar ecological requirements. In British Columbia, plants such as Knapweed, introduced to arid grasslands, and Purple Loosestrife, introduced to marsh and riparian areas, are rapidly becoming dominant plant species in their respective ecosystems. The interactions between native species are altered or destroyed by these exotic species, and can result in the loss of native biodiversity. 3. Pollution Atmospheric and hydrologic pollution have f