Environmental studies UG course Unit 1.pptx

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1. Course title: Environmental Studies Semester-II Credits-2 B.Sc. (Hons) – M. Sc. Environmental Sciences

2. Unit-I The Multidisciplinary Nature of Environmental Studies, Definition, Scope and importance of Environmental Studies. Biotic and abiotic components of environment, need for environmental awareness Concept of Ecosystem, concept of an ecosystem, structure and function of an ecosystem, producers, consumers and decomposers, energy flow in the ecosystem, ecological succession, food chains, food webs and ecological pyramids Planet Earth as an ecosystem: Lithosphere, Hydrosphere, Atmosphere, Biosphere, Biodiversity and its conservation.

3. The Multidisciplinary Nature of Environmental Studies Introduction to environment: The word environment is derived from the French word ‘ environner ’ which means to ‘ encircle or surround ’. Thus, our environment can be defined as “ the Social, Cultural and Physical conditions that surround, affect and influence the survival, growth and development of people, animals and plants ” This broad definition includes the natural world and the technological environment as well as the cultural and social contexts that shape human lives. It includes all factors (living and nonliving) that affect an individual organism or population at any point in the life cycle; set of circumstances surrounding a particular occurrence and all the things that surrounds us.

4. The Multidisciplinary Nature of Environmental Studies SEGMENTS OF ENVIRONMENT Environment consists of four segments. 1. Atmosphere- Blanket of gases surrounding the earth. 2. Hydrosphere- Various water bodies present on the earth. 3. Lithosphere- Contains various types of soils and rocks on the earth. 4. Biosphere- Composed of all living organisms and their interactions with the environment.

5. The Multidisciplinary Nature of Environmental Studies The Environment studies is a multi-disciplinary science because it comprises various branches of studies like chemistry, physics, medical science, life science, agriculture, public health, sanitary engineering etc. It is the science of physical phenomena in the environment. It studies about the sources, reactions, transport, effect and fate of physical and biological species in the air, water, soil and the effect of from human activity upon these. As the environment is complex and actually made up of many different environments like natural, constructed and cultural environments, environmental studies is inter-disciplinary in nature including the study of biology, geology, politics, policy studies, law, religion engineering, chemistry and economics to understand the humanity’s effects on the natural world. This subject educates the students to appreciate the complexity of environmental issues and citizens and experts in many fields. By studying environmental science, students may develop a breadth of the interdisciplinary and methodological knowledge in the environmental fields that enables them to facilitate the definition and solution of environmental problems.

6. Definitions Odum, E. P. (1971) "Environmental studies is the interdisciplinary academic field that studies human interaction with the environment in order to understand and mitigate human impact on the natural world.“ Miller, G. T. (1999) "Environmental science is an interdisciplinary study that examines the interactions between humans and nature, including aspects of biology, chemistry, physics, geology, and social sciences.“ UNESCO (1975) "Environmental studies refer to the systematic study of human interaction with their surroundings, including the natural, social, and built environments, aimed at developing sustainable solutions to environmental problems.“ Rajan, S. R. (1985) "Environmental studies encompass the study of the environment’s physical, chemical, biological, and social components, emphasizing conservation, pollution control, and sustainable development."

7. Definitions Carson, R. (1962) "Environmental studies involve understanding the interdependence of living organisms and their surroundings, including the effects of human activity on natural ecosystems.“ Park, C. (2001) "Environmental studies is the systematic study of natural and human environments with a focus on the conservation of biodiversity, management of resources, and sustainability of human activities.“ Enger & Smith (2004) "Environmental science is the field that investigates the relationships between human populations, resource use, pollution, and ecosystem health, focusing on solutions to contemporary environmental challenges."

8. Scope of Environmental Studies Environmental studies as a subject has a wide scope. It includes a large number of areas and aspects, which may be summarized as follows: Natural resources - their conservation and management Ecology and Biodiversity Environmental pollution and control Human population and environment Social issues in relation to development and environment

9. Scope of Environmental Studies These are the basic aspects of environmental studies which have a direct relevance to every section of society. Several career options have emerged in these fields that are broadly categorized as: Research and development in environment : Skilled environmental scientists have an important role to play in examining various environmental problems in a scientific manner and carry out R&D activities for developing cleaner technologies and promoting sustainable development. Green advocacy : With increasing emphasis on implementing various Acts and Laws related to environment, need for environmental lawyers has emerged, who should be able to plead the cases related to water, air, forest, wildlife, pollution and control etc.

10. Scope of Environmental Studies (iii) Green marketing : While ensuring the quality of products with ISO mark, now there is an increasing emphasis on marketing goods that are environment friendly. Such products have ecomark or ISO 14000 certification. Environmental auditors and environmental managers would be in great demand in the coming years. (iv) Green media : Environmental awareness can be spread amongst masses through mass media like television, radio, newspaper, magazine, hoardings, advertisements etc., for which environmentally educated persons are required. (v) Environmental consultancy : Many non-government organizations, industries and government bodies are engaging environmental consultants for systematically studying and tackling environment related problems.

11. Importance of Environmental Studies The importance of environmental studies is that, the current trend of environmental degradation can be reversed if people of educated communities are organized, empowered and experts are involved in sustainable development. Environmental factors greatly influence every organism and their activities. At present a great number of environmental issues, have grown in size and complexity day by day, threatening the survival of mankind on earth. These issues are studied besides giving effective suggestions in the environment studies. The environment studies enlighten us, about the importance of protection and conservation of our natural resources, indiscriminate release of pollution into the environment etc.

12. Importance of Environmental Studies Environment studies have become significant for the following reasons: 1. Environment Issues being of International Importance: It has been well recognized that environment issues like global warming, ozone depletion, acid rain, marine pollution and loss of biodiversity are not merely national issues but are global issues and hence must be tackled with international efforts and cooperation. 2. Problems Cropped in The Wake of Development: Development, in its wake gave birth to Urbanization, Industrial Growth, Transportation Systems, Agriculture and Housing etc. However, it has become phased out in the developed world. The North, to cleanse their own environment has, fact fully, managed to move ‘dirty’ factories to South. When the West developed, it did so perhaps in ignorance of the environmental impact of its activities. Evidently such a path is neither practicable nor desirable, even if developing world follows that. 3. Explosively Increase in Pollution: World census reflects that one in every seven persons in this plant lives in India. Evidently with 16 per cent of the world's population and only 2.4 per cent of its land area, there is a heavy pressure on the natural resources including land. Agricultural experts have recognized soils health problems like deficiency of micronutrients and organic matter, soil salinity and damage of soil structure.

13. Importance of Environmental Studies 4. Need for An Alternative Solution : It is essential, specially for developing countries to find alternative paths to an alternative goal. We need a goal as under: A goal, which ultimately is the true goal of development an environmentally sound and sustainable development. A goal common to all citizens of our earth. 5. Need To Save Humanity From Extinction : It is incumbent upon us to save the humanity from extinction. Consequences to our activities cause destructing the environment and depleting the biosphere, in the name of development. 6. Need For Wise Planning of Development : Our survival and sustenance depend. Resources withdraw, processing and use of the product have all to be synchronized with the ecological cycles in any plan of development. Our actions should be planned ecologically for the sustenance of the environment and development.

14. Biotic and Abiotic Components of Environment The environment is made up of two main components: biotic (living) and abiotic (non-living) factors. These components interact with each other to sustain life and ecosystems. 1. Biotic Components Biotic components refer to all living organisms in an ecosystem. They can be classified into three main groups: Producers (Autotrophs) : Organisms like plants, algae, and some bacteria that produce their own food through photosynthesis or chemosynthesis. Consumers (Heterotrophs) : Organisms that depend on other organisms for food, including herbivores, carnivores, omnivores, and decomposers. Decomposers (Saprotrophs) : Bacteria and fungi that break down dead organic matter, recycling nutrients into the ecosystem.

15. Biotic and Abiotic Components of Environment 2. Abiotic Components Abiotic components are the non-living physical and chemical factors that influence an ecosystem. They include: Climate : Temperature, humidity, precipitation, and wind. Soil : Provides minerals and nutrients essential for plant growth. Water : A crucial component for all life forms. Air : Oxygen, carbon dioxide, and nitrogen are vital for respiration and photosynthesis. Sunlight : The primary energy source driving photosynthesis.

16. Need for Environmental Awareness 1. Growing Population : A population of over thousands of millions is growing at 2.11 per cent every year. Over 17 million people are added each year. It puts considerable pressure on its natural resources and reduces the gains of development. Hence, the greatest challenge before us is to limit the population growth. Although population control does automatically lead to development, yet the development leads to a decrease in population growth rates. 2. Poverty : India has often been described a rich land with poor people. The poverty and environmental degradation are mixed with one another. The vast majority of our people are directly dependent on the nature resources of the country for their basic needs of food, fuel shelter and fodder. About 40% of our people are still below the poverty line. 3. Environment degradation has adversely affected the poor who depend upon the resources of their immediate surroundings. Thus, the challenge of poverty and the challenge of environment degradation are two facets of the same challenge. 4. Agricultural Growth : The people must be made familiar with the methods to sustain and increase agricultural growth without damaging the environment. High yielding varieties have caused soil salinity and damage to physical structure of soil.

17. Need for Environmental Awareness 5. Need to Increase Ground water : It is essential of rationalizing the use of groundwater. Factors like community wastes, industrial effluents, chemical fertilizers and pesticides have polluted our surface water and affected quality of the groundwater. It is essential to restore the water quality of our rivers and other water bodies. Suitable strategies for conservation of water, provision of safe drinking water and keeping water bodies clean should be developed. 6. Development and Forests : Forests serve catchments for the rivers. With increasing demand of water, plan to harness the mighty river through large irrigation projects were made. Certainly, these would submerge forests; displace local people, damage flora and fauna. As such, the dams on the river Narmada, Bhagirathi and elsewhere have become areas of political and scientific debate. Forests in India have been shrinking for several centuries owing to pressures of agriculture and other uses. Vast areas that were once green, stand today as waste lands. These areas are to be brought back under vegetative cover. The tribal communities inhabiting forests, respects the trees, birds and animals give them sustenance. We must recognize the role of these people in restoring and conserving forests. The modern knowledge and skills of the forest department should be integrated with the traditional knowledge and experience of the local communities. The strategies for the joint management of forests should be evolved in a well-planned way. Degradation of Land : At present out of the total 329 mha of land, only 266 mha possess any potential for production. Of this, 143 mha is agricultural land nearly and 85 suffers from varying degrees of soil degradation. Of the remaining 123 mha , 40 are completely unproductive. The remaining 83 mha is classified as forest land, of which over half is denuded to various degrees. Nearly 406 million head of livestock have to be supported on 13 mha , or less than 4 per cent of the land classified as pasture land, most of which is overgrazed. Thus, out of 226 mha , about 175 mha or 66 per cent is degraded to varying degrees. Water and wind erosion causes further degradation of almost 150 mha This degradation is to be avoided.

18. Need for Environmental Awareness 8. Evil Consequences of Urbanization : Nearly 27% of Indians live in urban areas. Urbanization and industrialization has given birth to a great number of environmental problems. Over 30 percent of urban Indians live in slums. Out of India’s 3,245 towns and cities, only 21 have partial or full sewerage and treatment facilities. Hence, coping with rapid urbanization is a major challenge. 9. Air and water Pollution : Majority of our industrial plants are using outdated and pollution causing technologies and makeshift facilities devoid of any provision of treating their wastes. A great number of cities and industrial areas have been identified as the worst in terms of air and water pollution. Acts are enforced in the country, but their implement is not so easy. The reason is their implementation needs great resources, technical expertise, political and social will. Again the people are to be made aware of these rules. Their support is indispensable to implement these rules.

19. Concept of ecosystem The  ecosystem  term was first coined by an ecologist Arthur Tansley in 1935. The ecosystem is a balance or equilibrium between living and non-living factors of the ecosystem where they tend to interact with each other. All living things, including plants, animals, and microorganisms, depend on non-living substances to survive and maintain the equilibrium of the natural environment. This relationship between the living and nonliving elements is studied by the study of ecosystems. In this article, we will discuss ecosystem structure, function, and types of ecosystems. In the word “ecosystem”, “eco” means environment, and “system,” refers to connected processes or elements.  Ecosystems are made up of both biotic (or alive) and abiotic (or nonliving) components.  It is a biological community where living and non-living components of the planet interact with each other. Ecosystem varies in the size and number of organisms they consist of. When the ecosystem is land-based it is called a terrestrial ecosystem and when it is water-based it is called an aquatic ecosystem.

20. Structure of Ecosystem The structure of an ecosystem is made of two main components: biotic and abiotic components. The biotic component interacts with the abiotic components to maintain the flow of energy. The energy is distributed in the environment. The ecosystem includes 2 main components for a working ecosystem: Biotic Component Abiotic Component

21. Components of an Ecosystem

22. Functions of Ecosystem The functions of the ecosystem are as follows: It regulates the essential ecological processes, supports life systems and renders stability. It is also responsible for the cycling of nutrients between biotic and abiotic components. It maintains a balance among the various trophic levels in the ecosystem. It cycles the minerals through the biosphere. The abiotic components help in the synthesis of organic components that involve the exchange of energy. So, the functional units of an ecosystem or functional components that work together in an ecosystem are: Productivity –  It refers to the rate of biomass production. Energy flow –  It is the sequential process through which energy flows from one trophic level to another. The energy captured from the sun flows from producers to consumers and then to decomposers and finally back to the environment. Decomposition –  It is the process of breakdown of dead organic material. The top-soil is the major site for decomposition. Nutrient cycling –  In an ecosystem nutrients are consumed and recycled back in various forms for the utilisation by various organisms.

23. Biotic Components Biotic components refer to all living components in an ecosystem. Based on nutrition, biotic components can be categorised into autotrophs, heterotrophs and saprotrophs (or decomposers). Producers include all autotrophs such as plants. They are called autotrophs as they can produce food through the process of photosynthesis. Consequently, all other organisms higher up on the food chain rely on producers for food. Consumers or heterotrophs are organisms that depend on other organisms for food. Consumers are further classified into primary consumers, secondary consumers and tertiary consumers. Primary consumers are always herbivores as they rely on producers for food. Secondary consumers depend on primary consumers for energy. They can either be carnivores or omnivores. Tertiary consumers are organisms that depend on secondary consumers for food. Tertiary consumers can also be carnivores or omnivores. Quaternary consumers are present in some food chains. These organisms' prey on tertiary consumers for energy. Furthermore, they are usually at the top of a food chain as they have no natural predators. Decomposers include saprophytes such as fungi and bacteria. They directly thrive on the dead and decaying organic matter. Decomposers are essential for the ecosystem as they help in recycling nutrients to be reused by plants.

24. Energy Flow in Ecosystem The chemical energy of food is the main source of energy required by all living organisms. This energy is transmitted to different trophic levels along the food chain. This energy flow is based on two different laws of thermodynamics: First law of thermodynamics, that states that energy can neither be created nor destroyed, it can only change from one form to another. Second law of thermodynamics, that states that as energy is transferred more and more of it is wasted. The flow of energy in the ecosystem is always in one direction or unidirectional. Even though producers tend to absorb 100% sun’s light energy in their capacity, they only pass on 10% of that energy to the next trophic level and then only 10% of that energy is passed into the next level.

25. Ecological Succession Succession is the order of colonization of species in an ecosystem from a barren or destroyed area of land. Mosses and lichens are the first species that inhabit an area. They make the area suitable for the growth of larger species such as grasses, shrubs and finally trees. Ecological succession is the gradual and natural process of change in the structure and composition of a biological community over time. Types of Ecological Succession These are the following types of ecological succession: Primary Succession Primary succession is the succession that starts in lifeless areas such as the regions devoid of soil or the areas 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. The soil then becomes the foundation of plant life. These plants help in the survival of different animals and progress from primary succession to the climax community. If this primary ecosystem is destroyed, secondary succession takes place.

26. Ecological Succession Secondary Succession Secondary succession occurs when the primary ecosystem gets destroyed. For eg. , a climax community gets destroyed by fire. It gets recolonized after the destruction. 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 arrives.

27. Ecological Succession Stages of Succession Pioneer Stage First organisms (lichens, mosses, bacteria) colonize barren land. These organisms help form soil by breaking down rocks. Intermediate Stage Small plants like grasses and shrubs grow. Animals begin to inhabit the area. More nutrients accumulate in the soil. Climax Community A stable and mature ecosystem develops. Includes large trees, diverse plant species, and complex animal interactions. Can remain unchanged unless disrupted by external forces.

28. Ecological Succession Seral Community “A seral community is an intermediate stage of ecological succession advancing towards the climax community.” A seral community is replaced by the subsequent 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. There are seven different types of seres : Types of Seres Explanation Hydrosere Succession in aquatic habitat. Xerosere Succession in dry habitat. Lithosere Succession on a bare rock surface. Psammosere Succession initiating on sandy areas. Halosere Succession starting in saline soil or water. Senile Succession of microorganism on dead matter. Eosere Development of vegetation in an era.

29. Ecological Succession Factors Affecting Succession Climate (temperature, rainfall) Soil quality Natural disturbances (fires, storms) Human activities (deforestation, pollution) Importance of Ecological Succession Helps ecosystems recover from disturbances. Increases biodiversity over time. Leads to the formation of stable ecosystems.

30. Food Chain The sun is the ultimate source of energy on earth. It provides the energy required for all plant life. The plants utilise this energy for the process of photosynthesis, which is used to synthesise their food. During this biological process, light energy is converted into chemical energy and is passed on through successive trophic levels. The flow of energy from a producer, to a consumer and eventually, to an apex predator or a detritivore is called the food chain. Dead and decaying matter, along with organic debris, is broken down into its constituents by scavengers. The reducers then absorb these constituents. After gaining the energy, the reducers liberate molecules to the environment, which can be utilised again by the producers.

31. Food Web There are unique interactions and relationships which are involved in the transportation of energy. The energy, once produced and captured, is distributed throughout the various living organisms. This transfer of energy is termed as the food web.

32. Ecological Pyramids An ecological pyramid is a graphical representation of the relationship between the different living organisms at different trophic levels. Charles Elton developed the concept of the pyramid of numbers. Later, G.Evylen Hutchinson and Raymond Lindeman developed the idea of the pyramid of energy or productivity. Types of Ecological Pyramid Three types of ecological pyramids exist. They are as follows: Pyramid of Numbers Pyramid of numbers displays the number of individual organisms at each trophic level in an ecosystem. Characteristics: Structure: It shows how many individuals make up each trophic level. Shape Variations: Normal (Upright) Pyramid: More individuals at the bottom (primary producers) than at higher trophic levels. Inverted Pyramid: Some ecosystems, especially those with large, long-lived producers (like trees), may have fewer individuals at the base compared to the next trophic level (e.g., insects or herbivores that feed on them). Example: A forest ecosystem might have one tree that supports many insect herbivores, resulting in an inverted pyramid when counting numbers.

33. Pyramid of Numbers In this type of ecological pyramid, the number of organisms in each trophic level is considered as a level in the pyramid. The pyramid of numbers is usually upright except for some situations like that of the detritus food chain, where many organisms feed on one dead plant or animal.

34. Pyramid of Biomass Pyramid of biomass represents the total mass (or dry weight) of living material (biomass) at each trophic level. Characteristics: Structure: It is measured in units such as grams per square meter (g/m²) and typically shows how biomass is distributed from producers to consumers. Shape Variations: Upright Pyramid: Common in terrestrial ecosystems where the total mass of plants (producers) exceeds that of herbivores and carnivores. Inverted Pyramid: Often seen in some aquatic ecosystems where the biomass of phytoplankton (producers) is less than that of the consumers (zooplankton) because phytoplankton reproduce rapidly.

35. Pyramid of Energy Pyramid of energy illustrates the amount of energy that is present at each trophic level, generally measured in kilojoules per square meter per year (kJ/m²/yr). Characteristics: Structure: Energy is measured as it flows through trophic levels, typically showing that only about 10% of the energy is transferred from one trophic level to the next (the 10% rule ). Shape: Always an upright pyramid because energy decreases as it moves up trophic levels due to energy lost as heat (metabolic processes, respiration) and waste. Example: Primary producers capture solar energy; herbivores consume a fraction of that energy; carnivores obtain even less energy from herbivores, and so on.

36. Key Concepts and Applications Trophic Efficiency and the 10% Rule: Trophic Efficiency: The proportion of energy transferred from one trophic level to the next. 10% Rule: Typically, only about 10% of the energy from one trophic level is available to the next level due to losses from respiration, heat, and waste. This rule explains why energy pyramids are always upright, with a dramatic reduction of energy as one moves upward. Implications for Ecosystem Management: Biodiversity: Understanding the distribution of biomass and energy can help in assessing ecosystem health and resilience. Conservation: Recognizing the energy limitations at higher trophic levels can inform strategies for protecting top predators and maintaining balance in food webs. Resource Management: Helps in planning sustainable harvesting practices and managing natural resources effectively.

37. Examples in Real-World Ecosystems Terrestrial Ecosystem (Forest): Pyramid of Numbers: May be inverted if a few trees support many insects. Pyramid of Biomass: Generally upright because the mass of trees is high relative to herbivores. Pyramid of Energy: Upright, with significant energy loss between trophic levels due to respiration and other metabolic processes. Aquatic Ecosystem (Ocean/Planktonic System): Pyramid of Numbers: Can be huge at the base with numerous small phytoplankton. Pyramid of Biomass: May be inverted because phytoplankton biomass at any given moment is low even though their production is high. Pyramid of Energy: Remains upright as energy is lost at each trophic transfer.

38. Planet Earth as an ecosystem Concept of a Global Ecosystem: Planet Earth can be viewed as a single, enormous ecosystem where every component, from microscopic bacteria to vast oceans, plays a role. The Gaia Hypothesis (proposed by James Lovelock and Lynn Margulis) suggests that Earth behaves as a self-regulating system where biotic and abiotic components interact to maintain conditions suitable for life. Major Components of Earth’s Ecosystem: Biosphere: All living organisms. Lithosphere: Earth's rocky outer layer. Hydrosphere: All water bodies. Atmosphere: The layers of gases surrounding Earth.

39. Lithosphere Lithosphere Definition: The lithosphere is the rigid, outermost layer of the Earth. It comprises the crust and the uppermost portion of the mantle. The term “ litho ” means rock, indicating its primary composition of solid rock. Extent and Thickness: Varies in thickness: approximately 5–10 km beneath the oceans and up to 200 km beneath continents. It forms a brittle layer that is broken into tectonic plates. Structural Composition A. Crust - Types of Crust: a) Continental Crust: Thicker (averaging ~35 km but can reach 70 km in some areas), Composed primarily of less dense, granitic rocks and Older and more complex in structure. b) Oceanic Crust: Thinner (averaging ~5–10 km), Composed mainly of dense, basaltic rocks and generally younger due to constant renewal at mid-ocean ridges. B. Upper Mantle - Role in the Lithosphere: Provides structural support and is partially solid and partially plastic and Plays a key role in heat transfer and tectonic processes. Interaction with Crust: The boundary between the crust and upper mantle is called the Mohorovičić discontinuity (Moho).

40. Hydrosphere Definition: The hydrosphere encompasses all water found on, under, and over the surface of Earth, it includes both liquid and frozen forms of water (and water vapor when considering its role in global processes). Scope and Importance: Covers approximately 71% of Earth's surface, Integral to life processes, climate regulation, and many geological processes and acts as a medium for biochemical reactions and nutrient transport. Major Components of the Hydrosphere A. Oceans : the largest component, comprising about 97% of Earth's water, serve as a major heat reservoir and play a critical role in regulating global climate. Features: Saline water (saltwater), divided into various basins and interconnected through currents and tides. B. Freshwater : Surface Fresh-water: Lakes and Rivers: Lakes are inland bodies of standing water; rivers are flowing channels and critical for drinking water, agriculture, and ecosystems. Groundwater: Water stored beneath the Earth’s surface in aquifers, supplies wells and springs; vital for irrigation and drinking water. C. Ice and Snow : Glaciers and Ice Caps: Large masses of ice found in polar regions and high-altitude mountains, Seasonal Snow and Sea Ice: Play an essential role in reflecting solar radiation (albedo effect) and influencing climate. D. Water Vapor : Atmospheric Water: Although part of the hydrosphere, water vapor exists in the atmosphere and key for weather formation, precipitation, and energy exchange.

41. The Water Cycle (Hydrologic Cycle) Major Processes Evaporation: Water from oceans, lakes, and other bodies turns into water vapor due to heat from the sun. Transpiration: Water released into the atmosphere by plants. Condensation: Water vapor cools and forms clouds. Precipitation: Water falls back to Earth as rain, snow, sleet, or hail. Infiltration and Percolation: Water soaks into the soil and recharges groundwater aquifers. Runoff: Excess water flows over land, returning to oceans and lakes. Importance of the Water Cycle : a) Climate Regulation: Distributes heat and moisture around the globe, b) Nutrient Transport: Moves dissolved minerals and nutrients essential for life and c) Ecosystem Sustainability: Supports diverse habitats and maintains ecological balance.

42. Atmosphere The atmosphere is a layer of gases surrounding the Earth, held in place by gravity. It plays a critical role in supporting life by regulating temperature, enabling weather and climate, and providing essential gases. Importance of the Atmosphere : a) Maintains Earth's temperature through the greenhouse effect, b) Shields the planet from harmful solar radiation, c) Facilitates weather patterns, climate, and the water cycle, d) Provides oxygen for respiration and carbon dioxide for photosynthesis. Layers of the Atmosphere : The Earth's atmosphere is divided into distinct layers based on temperature and composition. Troposphere (0–12 km) The lowest layer where most weather phenomena occur, temperature decreases with altitude, contains about 75% of the atmosphere’s mass. Significance: Supports all life and is critical for climate and weather and Greenhouse gases trap heat, maintaining a livable temperature.

43. Atmosphere B) Stratosphere (12–50 km) Characteristics: a) contains the ozone layer, which absorbs harmful ultraviolet (UV) radiation, b) temperature increases with altitude due to ozone absorption of solar radiation, c) very stable, making it ideal for commercial air travel. Significance: Protects living organisms from UV radiation and supports the global circulation of air masses. C) Mesosphere (50–85 km) Characteristics: a) coldest atmospheric layer, b) temperature decreases with altitude, c) Burns up most meteors due to friction. Significance: Protects Earth from meteorite impacts. D) Thermosphere (85–600 km) Characteristics: a) extremely high temperatures due to solar radiation absorption, b) contains the ionosphere, where solar radiation ionizes gases, enabling radio communication. Significance: Hosts auroras (Northern and Southern Lights) and supports satellite and space station orbits. E) Exosphere (600 km and beyond) Characteristics: a) the outermost layer where atmosphere merges with space, b) contains sparse molecules drifting into space. Significance: Transition zone between Earth's atmosphere and outer space.

44. Composition of Atmosphere Gas Percentage (%) Role Nitrogen (N₂) 78% Essential for plant growth (nitrogen cycle). Oxygen (O₂) 21% Required for respiration and combustion. Argon (Ar) ~0.93% Inert gas with minimal impact. Carbon Dioxide (CO₂) ~0.04% Key in the greenhouse effect and photosynthesis. Water Vapor (H₂O) Varies (0-4%) Influences weather, climate, and precipitation. Ozone (O₃) Trace amounts Absorbs harmful UV radiation in the ozone layer.

45. Biosphere The biosphere is the region where life exists along with the air and the land. It is the combination of all types of ecosystems on Earth which integrates all the biological communities and their interactions or relationships with the environment. The living communities include animals, bacteria, plants, fungi, and human beings. It is derived from the Greek word “bios” and “ sphaira ” which means “Life” and “Earth’s shape” respectively. The term was coined by Eduard Suess, an English Austrian scientist, in his book titled “The Face of Earth” in which he discussed the relationships between living things and how the Earth supports them. The biosphere encompasses everything from the deepest tree roots to the shadowy depths of the ocean, dense rainforests, and lofty mountaintops. It is also called the ecosphere. It can be found up to 12500 meters above sea level and at least 8000 meters deep in the ocean. Aside from natural biosphere, manmade ones have also been created, such as Biosphere 2, which is perhaps the biggest closed ecosystem ever made by humans.

46. The biosphere, or “zone of life,” an energy-diverting layer that uses the matter of Earth to create living substance, was created by this development of life in the thin outer layer of the geosphere.

47. Biodiversity and its conservation Biological diversity or biodiversity refers to the different life forms and habitats found in a defined area. UNEP (1992) defines it “as the variety and variability of all animals, plants and micro-organisms and the ecological complexes of which they are a part”. The convention on Biological Diversity defines biodiversity as “The variability among living organisms from all sources including, interalia terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part; this includes diversity within species, between species and of ecosystems”. Biodiversity: It is defined as the totality of genes, species and ecosystems of a given region. The term biodiversity was coined by W.G. Rosen (1985). Norman Myers introduced the concept of biodiversity. The term biodiversity was popularised by Edward Wilson.

48. Importance of Biodiversity All the organisms are important links in the food chains operating in different habitats. If any of the links is removed then the whole ecosystem faces the consequences. It acts as a source of gene pool or gene bank for various breeding programs. For example, one of the rice species resistant to the rice pest Nilaparvata lugens (Brown planthopper) was discovered from the wildlife gene pool and cultivated. This way serious damage due to this pest was prevented. Drugs have been developed from the raw materials obtained from plants and other organisms. Biodiversity is of great ecological, economic and aesthetic value

49. Levels of Biodiversity Genetic diversity Species diversity Ecological or Ecosystem diversity Genetic Diversity Greater the genetic diversity among organisms of a species, more sustenance it has against environmental perturbations. The genetically uniform populations are highly prone to diseases and harsh environment. The genetic variation shown by Rauwolfia vomitoria (poison devil’s-pepper) is in terms of potency and concentration of the chemical reserpine. There are more than 50,000 genetically different strains of rice and 1000 varieties of mango in India.

50. Levels of Biodiversity Species Diversity The two important measures of species diversity are: species richness and species evenness. Species Richness : It refers to the number of different species per unit area in an ecological community. Here neither abundance nor distribution of species is taken into account. For example, if an area has birds, amphibians, herbivores, insects, small carnivores, reptiles and plants of various types then it is species rich. Species Evenness: It is the relative abundance with which each species is represented in an area. This aspect focuses on how many members of different species are present in an area. For example, if in an area number of wolves, foxes and wild dogs is 1000, 90 and 700 respectively then the area is uneven in species richness. But if the same species are in 1000,950 and 970 respectively then it is relatively even in species richness. The number and variety of individuals determine the level of diversity in an ecosystem. The Western Ghats have a greater diversity of amphibian species than the Eastern Ghats. Approximately 181 amphibian species are recorded in the Western Ghats.

51. Levels of Biodiversity Ecological Diversity: Ecological diversity is related to species diversity and genetic diversity. India has greater ecosystem diversity than a Scandinavian country like Norway; India has several ecosystems or biomes like rain forests, deserts, wetlands, mangroves, coral reefs, estuaries and alpine meadows. GLOBAL BIODIVERSITY According to IUCN (2004), the total number of plant and animal species described is over 1.5 million. y The species inventories for taxonomic groups in temperate countries or regions are more complete than those in tropical countries or regions. Robert May, has put the global species diversity at about seven million by his conservative and scientific estimate. Till now, from all the recorded species more than 70% are animals and of this 70% are insects. y Plants account for about 22% which include algae, fungi, bryophytes, gymnosperms and angiosperms.

52. Biodiversity in India India is one of the 12 mega biodiverse countries of the world. The 12 mega biodiverse countries are - United States of America, Mexico, Colombia, Ecuador, Peru, Venezuela, Brazil, Democratic Republic of Congo, South Africa, Madagascar, India, Malaysia, Indonesia, Philippines, Papua New Guinea, China, and Australia. India has only 2.4% of the land area of the world but it has 8.1% of the global species biodiversity. y There are about 4500 species of plants and 90,000 – 1,00,000 species of animals. Many species are yet to be discovered and named. Only 22% of the total species have been recorded so far according to Robert May’s global estimate. India probably has more than 1,00,000 plants and 3,00,000 animals' species at to be discovered and described. PATTERNS OF BIODIVERSITY : Biodiversity in the world varies with change in altitude and latitude. Favourable environmental conditions favour speciation and thus makes it possible for a larger number of species to exist, i.e., biodiversity is more in such areas than in others.

53. Loss of Biodiversity IUCN Red List (2004) documents the extinction of 784 species in the last 500 year that includes 359 invertebrates, 338 vertebrates and 87 plants. Some of the animals that have become extinct in recent times are given below: ○ Steller’s sea cow (Russia) ○ Dodo (Mauritius) ○ Thylacine (Australia) ○ Quagga (Africa). 27 species have become extinct in the last twenty years alone. Amphibians are more vulnerable to extinction. At present the percentage of threat of extinction among organisms is given below: ○ 31% of gymnosperms ○ 32% of amphibians ○ 12% of bird species ○ 23% of mammals There have been five episodes of mass extinction since the origin of life, but current rate of extinction is 100–1000 times faster due to human activities. Loss of biodiversity in a region can lead to the following: ○ Decrease in plant production. ○ Lowered resistance to environmental perturbation. ○ Increased variability in ecosystem processes like water use, pest or disease cycles, plant productivity, etc.

54. CAUSES FOR LOSS OF BIODIVERSITY

55. Mass extinction Mass extinction in ecology refers to an extinction of species at a faster rate in short geological period of time. At present sixth mass extinction is going on which is referred to as the Anthropocene extinction. In the past five extinctions have occurred: Ordovician- silurian Extinction (440 million years ago)-small marine animals got extinct. Devonian Extinction (365 million years ago)- Extinction of tropical marine species. Permian- triassic Extinction (250 million years ago)- Largest mass extinction that wiped out numerous species including vertebrates. Triassic- jurassic Extinction (210 million years ago)- Numerous species of vertebrates died paving the way for the dinosaurs to flourish. Cretaceous-tertiary Extinction or K-T extinction (65 million years ago)- Non-avian dinosaurs, other animals and many plants got extinct. *(K is used to depict Cretaceous period)

56. REASONS FOR CONSERVING BIODIVERSITY The reasons for conserving biodiversity can be grouped into three categories: ○ Narrowly utilitarian ○ Broadly utilitarian ○ Ethical Narrowly Utilitarian Reasons These are obvious reasons which focus on present day needs. Human beings derive a number of economic benefits like food, fibre , firewood, industrial products (resigns, gums, dyes, tannin, etc.) and medicinal products. More than 25% of the drugs are derived from plants and about 25000 species of plants are used by native people as traditional medicine. Broadly Utilitarian Reasons: Biodiversity plays a major role in providing various ecosystem services, which cannot be given a price-tag and these focus on well-being of our planet for future generations, they are: Production of oxygen. ○ Pollination of flower, without which fruits or seeds are not produced ○ Aesthetic pleasure like bird watching, watching spring flower, walking through the thick forest, waking up to bulbul’s song, etc. Ethical Reasons Every species has an intrinsic value, even if it is not of any economic value to us. We have a moral duty to care for their well-being and pass on the biological legacy in a proper form to our future generations.

57. Conservation of Biodiversity In Situ Strategies In situ conservation means ‘on-site conservation’. Here, the plant or animal species are protected in their natural habitat. This is carried on by two methods: ○ By protecting or cleaning up the habitat itself. ○ By defending the species from predators. Biosphere Reserves Protected area for wildlife. It has 3 zones: ○ Core zone – No human activity is permitted in this zone. ○ Buffer zone – Limited human activity is allowed in this zone. ○ Manipulation zone – A large number of human activities are allowed in this zone.

58. REASONS FOR CONSERVING BIODIVERSITY Objectives of Biosphere Reserve To conserve the diversity and integrity of biotic communities. To provide areas for ecological and environmental research. To provide facilities for educational training. Number of Biosphere Reserves There are currently 714 biosphere reserves in 129 countries. In India there are 14 biosphere reserves.

59. BIODIVERSITY HOTSPOTS Extremely rich in species with high degree of endemism. Biodiversity hotspots have been identified for maximum protection to the endemic and endangered species. At present biodiversity hotspots cover more than 15.7% area on the earth. Criteria for an Area to be Labelled as ‘Hotspot’ It must contain 1,500 species of vascular plants or > 0.5 percent of the world’s total as endemics. It has lost one third or 75% of its primary vegetation.

60. Conservation of Biodiversity Number of ‘Hotspots’: There are 34 hotspots on the globe. Three are in India- ○ Western Ghats ○ Indo-Burma Region ○ Himalayan region NATIONAL PARKS AND WILDLIFE SANCTUARIES India has (according to September 2002 list) 90 National Parks and 448 Wildlife Sanctuaries. Jim Corbett National Park: ○ It is the first to be established in India, in the Nainital district of Uttarakhand. ○ It was established in the year 1936 and here Project Tiger was launched in 1973. ○ It spans over 520 square kilometres and comprises of hills, marshy areas, riverine belts, grasslands and large lake.

61. Conservation of Biodiversity Scared Forests: These are the undisturbed forests without any human intervention and have a special religious importance to a particular culture. y The area is usually dedicated to a local deity. In India these sacred groves were brought under the Wildlife protection Act, in 2002 Such forests include a number of rare, endangered and endemic species. Sacred Groves in India: Khasi and Jaintia hills in Meghalaya. Western Ghat regions of Karnataka and Maharashtra. Aravalli Hills of Rajasthan. Sarguja , Chanda and Bastar areas of Madhya Pradesh.

62. Conservation of Biodiversity EX SITU CONSERVATION y Botanical gardens, zoological parks and arboretum are the conventional methods of ex situ conservation. y Cryopreservation is a method of conservation by storage of live cells, tissues and other biological sample at ultra low temperatures for a very long period; gametes of threatened species can be preserved in viable and fertile condition for long periods using this technique. y Plants are propagated using tissue culture method (micropropagation). Seeds of many different genetic strains of commercially important plants are kept viable for long periods in seed banks. India has today 122 botanical gardens and 275 zoos (zoos, deer parks, aquaria and safari parks).

63. Conservation of Biodiversity

64. Conservation of Biodiversity ENDEMISM When a native species is found in a particular geographical area, this state is called endemism. Endemic species are not found naturally in any other geographical area. CONVENTIONS ON BIODIVERSITY The Earth Summit: This is the historic convention on Biological Diversity held in Rio de Janeiro in 1992. It called upon all the nations to take appropriate measures for: ○ Conservation of biodiversity and ○ sustainable utilisation of the benefits from biodiversity. The World Summit on Sustainable Development This was held in 2002, in Johannesburg, South Africa. y 190 countries signed their commitment to achieve a significant reduction in the current rate of biodiversity loss at global, regional and local levels by 2010.