Environment part 1.pdf

 Contents Student Notes: UNIT - 1...............................................................................................................................

 Contents Student Notes: UNIT - 1.......................................................................................................................................... 5 CHAPTER - 1 - UNDERSTANDING ECOLOGY.................................................................................... 5 1. Understanding Ecology.............................................................................................................. 5 1.1. Concept of Ecology and Environment................................................................................. 5 1.2. Levels of Organisation of Ecology....................................................................................... 5 1.3. Functions of an Ecosysytem................................................................................................ 8 1.4. Energy Flow in an Ecosystem.............................................................................................. 8 1.5. Food Chain........................................................................................................................ 10 1.5.1. Definition................................................................................................................... 10 1.5.2. Types of Food Chain................................................................................................... 10 1.6. Food Web.......................................................................................................................... 10 1.7. Ecological Pyramid............................................................................................................ 11 1.7.1. Definition................................................................................................................... 11 1.7.2. Types of Ecological Pyramids..................................................................................... 11 1.8. Ecological Productivity...................................................................................................... 14 1.8.1. Definition................................................................................................................... 14 1.9. Biological Interaction........................................................................................................ 14 1.9.1. Types of Biotic Interactions in a Food Web................................................................ 15 1.10. Ecological Succession...................................................................................................... 16 1.10.1. Types of Succession.................................................................................................. 16 1.11. Biogeochemical Cycles.................................................................................................... 17 1.11.1. Carbon Cycle............................................................................................................ 18 1.11.2. Nitrogen Cycle.......................................................................................................... 18 1.12. Ecosystem Services......................................................................................................... 21 1.13. UPSC Previous Years Question........................................................................................ 23 1.14. Vision IAS Previous Years Questions............................................................................... 24 CHAPTER - 2 - TYPES OF ECOSYSTEM........................................................................................... 27 2. Types of Ecosystem.................................................................................................................. 27 2.1. Introduction...................................................................................................................... 27 m 2.2. Types of Ecosystem........................................................................................................... 27 co 2.3. Terrestrial Ecosystems....................................................................................................... 27 l. ai gm 2.4. Forest Vegetation in India................................................................................................. 30 @ 2.4.1. Tropical Evergreen Forests......................................................................................... 30 27 2.4.2. Tropical Deciduous Forests........................................................................................ 31 gn ha 2.4.3. Moist Deciduous Forests............................................................................................ 31 si 2.4.4. Dry Deciduous Forests............................................................................................... 31 2.4.5. The Thorn Forests and Scrubs.................................................................................... 31 2.4.6. Montane Forests........................................................................................................ 31 2.4.7. Mangrove Forests...................................................................................................... 32 2.5. State of Forest Report....................................................................................................... 33 2.6. Conservation and Management of Forest........................................................................ 34 2.6.1. National Forest Policy, 1988....................................................................................... 34 2.6.2. Social Forestry............................................................................................................ 37 2.6.3. National Afforestation Programe............................................................................... 38 2.6.4. Green India Mission (GIM)......................................................................................... 38 2.6.5. Compensatory Afforestation...................................................................................... 39 2.6.6. Other Acts for Forest Conservation............................................................................ 40 2.7. Aquatic Ecosystems........................................................................................................... 42 2.7.1. Factors Limiting the Productivity of Aquatic Habitats................................................ 42 2.8. Estuarine Ecosystem......................................................................................................... 43 2.8.1. Importance of Estuaries............................................................................................. 44 DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 1 www.visionias.in # 8468022022 ©Vision IAS  2.8.2. Estuarine Vegetation.................................................................................................. 44 Student Notes: 2.8.3. India Estuarine Ecosystem.......................................................................................... 45 2.8.4. Issues of Indian Estuarine Ecosystem......................................................................... 45 2.9. Vision IAS Previous Year Questions................................................................................... 45 CHAPTER - 3 - UNDERSTANDING ECOLOGY.................................................................................. 52 3. Wetlands.................................................................................................................................. 52 3.1. Introduction...................................................................................................................... 52 3.2. Types of Wetlands............................................................................................................. 52 3.3. Distinction Between Lake and Wetland............................................................................ 53 3.4. Importance of Wetlands................................................................................................... 54 3.5. Reasons for depletion....................................................................................................... 54 3.6. Mitigation.......................................................................................................................... 55 3.7. Measure to Protect Wetland............................................................................................. 55 3.7.1. Global Conservation Efforts....................................................................................... 55 3.7.2. Conservation Efforts by India..................................................................................... 56 3.8. UPSC Previous Years Questions......................................................................................... 58 3.9. Vision IAS Previous Year Test Series Questions................................................................. 59 CHAPTER - 4 - MANGROVES......................................................................................................... 67 4. Mangroves............................................................................................................................... 67 4.1. Introduction...................................................................................................................... 67 4.2. Characteristics of Mangrove Vegetation........................................................................... 67 4.3. Mangroves in India............................................................................................................ 68 4.4. Importance of Mangroves................................................................................................. 69 4.5. Threats to Mangroves....................................................................................................... 69 4.6. Conservation of Mangroves.............................................................................................. 70 4.7. UPSC Previous Years Questions......................................................................................... 70 CHAPTER - 5 - CORALS................................................................................................................. 71 5. Corals....................................................................................................................................... 71 5.1. Coral Reef.......................................................................................................................... 71 5.2. Coral Reef Relief Features................................................................................................. 71 5.2.1. Fringing Reefs (Shore Reefs)...................................................................................... 72 m co 5.2.2. Barrier Reefs............................................................................................................... 72 l. ai 5.2.3. Atolls.......................................................................................................................... 72 gm 5.3. Development of Major Coral Reef Types.......................................................................... 73 @ 27 5.4. Importance of Corals......................................................................................................... 73 gn 5.5. Coral Bleaching................................................................................................................. 73 ha si 5.5.1. Natural Causes of Coral Bleaching............................................................................. 74 5.5.2 Anthropogenic Cause of Coral Bleaching.................................................................... 75 5.6. Impact of Coral Bleaching................................................................................................. 76 5.7. Global Initiatives............................................................................................................... 76 5.7.1. International Coral Reefs Initiative (ICRI)................................................................... 76 5.7.2. Global Coral Reef monitoring network...................................................................... 76 5.7.3. International Coral Reef Action Network (ICRAN)...................................................... 76 5.7.4. Coral Triangle Initiative.............................................................................................. 76 5.8. Conservation of Coral Reefs in India................................................................................. 77 5.9. Steps to be taken.............................................................................................................. 78 5.10. UPSC Previous Years Questions....................................................................................... 79 5.11. Vision IAS Previous Years Test Series Questions.............................................................. 80 UNIT - 2........................................................................................................................................ 87 CHAPTER - 6 - BIODIVERSITY........................................................................................................ 87 6. Biodiversity.............................................................................................................................. 87 6.1. Introduction...................................................................................................................... 87 6.2. Levels of biodiversity......................................................................................................... 87 DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 2 www.visionias.in # 8468022022 ©Vision IAS  6.3. Measurement of Biodiversity............................................................................................ 88 Student Notes: 6.3.1. Patterns of Biodiversity.............................................................................................. 89 6.4. The Biogeographic Zones of India and their Biodiversity.................................................. 90 6.4.1. Trans Himalayan Zone................................................................................................ 90 6.4.2. The Himalayas............................................................................................................ 90 6.4.3. The Desert.................................................................................................................. 91 6.4.4. The Semi-Arid............................................................................................................. 91 6.4.5. The Western Ghats..................................................................................................... 91 6.4.6. The Deccan Peninsula................................................................................................ 92 6.4.7. The Gangetic Plain..................................................................................................... 92 6.4.8. North-East India......................................................................................................... 92 6.4.9. The Islands................................................................................................................. 93 6.4.10. The Coasts................................................................................................................ 93 6.5. Biodiversity Hotspots........................................................................................................ 94 6.5.1. Biodiversity Hotspots in India.................................................................................... 95 6.5.2. India- A Mega-Biodiversity Country........................................................................... 97 6.6. UPSC Previous Year Questions.......................................................................................... 97 6.7. Vision IAS Previous Year Questions................................................................................... 99 CHAPTER - 7 - CONSERVATION OF BIODIVERSITY...................................................................... 100 7. Conservation of Biodiversity.................................................................................................. 100 7.1. Causes of Biodiversity loss.............................................................................................. 100 7.2. IUCN Red List of Endangered Species............................................................................. 103 7.3. Illegal Wildlife Trade........................................................................................................ 105 7.4. Human- Animal Conflict.................................................................................................. 106 7.5. Conservation Strategies.................................................................................................. 108 7.5.1. In-Situ conservation methods.................................................................................. 108 7.5.2. Ex-Situ conservation Strategies................................................................................ 109 7.6. UPSC Previous Year Questions........................................................................................ 110 7.7. Vision IAS Previous Year Questions................................................................................. 111 CHAPTER - 8 - PROTECTED AREAS NETWORK............................................................................ 114 8. Protected Areas Network....................................................................................................... 114 m co 8.1. Protected Areas of India................................................................................................. 114 l. ai 8.2. Wildlife Sanctuaries........................................................................................................ 114 gm 8.3. National Parks................................................................................................................. 115 @ 27 8.4. Marine Protected Areas.................................................................................................. 115 gn 8.5. Community Reserves & Conservation Reserves............................................................. 116 ha si 8.6. Regulations/Laws relating to Protected Areas (PAs)....................................................... 116 8.7. Other Areas of Importance for Conservation.................................................................. 116 8.7.1. Eco-Sensitive Zones.................................................................................................. 116 8.7.2. Coastal Regulation Zones (CRZ)................................................................................ 117 8.7.3. Sacred Groves in India.............................................................................................. 120 8.8. Biosphere Reserves......................................................................................................... 121 8.8.1. Core Areas................................................................................................................ 122 8.8.2. Buffer Zones............................................................................................................. 122 8.8.3. Transition Area......................................................................................................... 122 8.8.4. Criteria for Designation of BR in India...................................................................... 122 8.8.5. Man and Biosphere (MAB) Program........................................................................ 123 8.8.6. World Network of Biosphere Reserves (WNBR)...................................................... 123 8.9. Biodiversity Heritage Sites.............................................................................................. 124 8.9.1. The criteria for identification of BHS........................................................................ 125 8.10. World Heritage Sites (WHS).......................................................................................... 126 8.10.1. Criteria for World Heritage Sites............................................................................ 126 8.11. Important Bird Areas (IBAs).......................................................................................... 127 DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 3 www.visionias.in # 8468022022 ©Vision IAS  8.12. UPSC Previous Year Questions...................................................................................... 127 Student Notes: 8.13. Vision IAS Previous Year Question................................................................................ 129 CHAPTER - 9 - POLICY AND INSTITUTIONAL MEASURES............................................................ 131 9. Policy and Constitutional Measures....................................................................................... 131 9.1. Policy Framework in India............................................................................................... 131 9.2. Legislative Framework in India........................................................................................ 133 9.2.1. Key Legislation in Detail........................................................................................... 135 9.3. Institutions...................................................................................................................... 140 9.3.1. National Green Tribunal (NGT)................................................................................. 140 9.3.2. Institutional structure under the Biodiversity Act, 2002.......................................... 141 9.3.3. Wildlife Crime and Control Bureau (WCCB)............................................................. 143 9.3.4. Botanical Survey of India.......................................................................................... 143 9.3.5. Zoological Survey of India (ZSI)................................................................................ 143 9.3.6. Central Zoo Authority (CZA)..................................................................................... 144 9.4. Global Efforts for Biodiversity Conservation................................................................... 145 9.4.1. Linkage between SDGs and Biodiversity.................................................................. 145 9.4.2. Convention on Biodiversity (CBD)............................................................................ 145 9.4.3. Sixth Annual Report to the CBD............................................................................... 147 9.5. UPSC Previous Year Questions........................................................................................ 147 CHAPTER - 10 - SPECIES SPECIFIC MEASURES............................................................................ 149 10. Species Specific Conservation Initiatives............................................................................. 149 10.1. Introduction.................................................................................................................. 149 10.2. Tiger.............................................................................................................................. 150 10.2.1. Conservation Efforts in India.................................................................................. 150 10.2.2. Global Efforts......................................................................................................... 154 10.3. Elephant........................................................................................................................ 155 10.3.1. Conservation Efforts in India.................................................................................. 155 10.3.2 Global Efforts.......................................................................................................... 157 10.4. Snow Leopard............................................................................................................... 157 10.4.1. Conservation Efforts in India.................................................................................. 158 10.4.2. Global Efforts......................................................................................................... 159 m co 10.5. Asiatic Lion.................................................................................................................... 159 l. ai 10.5.1. Asiatic Lion Conservation Project........................................................................... 159 gm 10.6. One-horned Rhino........................................................................................................ 159 @ 27 10.6.1. Conservation Efforts in India.................................................................................. 160 gn 10.7. Indian Ganges Dolphin.................................................................................................. 161 ha si 10.7.1. Conservation Efforts in India.................................................................................. 161 10.8. Dugong.......................................................................................................................... 162 10.8.1. National Conservation Plan.................................................................................... 162 10.9. Vultures......................................................................................................................... 163 10.9.1. Efforts in India........................................................................................................ 164 10.9.2. Global Efforts......................................................................................................... 165 10.10. Great Indian Bustard................................................................................................... 165 10.10.1. National Guidelines for Recovery of Bustards, 2013............................................ 166 10.11. UPSC Previous Year Questions.................................................................................... 166 Copyright © by Vision IAS All rights are reserved. No part of this document may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without prior permission of Vision IAS. DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 4 www.visionias.in # 8468022022 ©Vision IAS si ha gn 27 @ gm ai l.co m  Student Notes: UNIT - 1 CHAPTER - 1 - UNDERSTANDING ECOLOGY 1. Understanding Ecology 1.1. Concept of Ecology and Environment Ecology can be defined as a scientific study of the interactions of organism with their physical environment and with each other. The term ecology is derived from the Greek word ‘oikos’ meaning ‘house’, combined with the word ‘logy’ meaning the ‘science of’ or ‘the study of ’. Literally, ecology is the study of the earth as a ‘household’, of plants, human beings, animals and micro-organisms. They all live together as interdependent components. The term ecology was first used by German zoologist Ernst Haeckel in 1869. An ecosystem is defined as a community of life forms in concurrence with non-living components, interacting with each other. The term ecosystem was coined by Arthur Tansley in 1935. Environment is the sum total of all conditions and influences that affect the development and life of all organisms on earth. Thus it can be said as one’s surrounding. Autecology: The study of relationship of individual species with the environment. Synecology: The study of plant communities in relation to their habitats of a given ecosystem. Gaia hypothesis: This refers to a scientific hypothesis which states that the earth is a complex living entity, with the sustenance of life dependent on the self-regulating interactions among organisms and their inorganic surroundings. For instance, climatic conditions depend on the interactions among living organisms like human beings and their non-living atmosphere, all of which regulate each other constantly. m The Gaia hypothesis is named after the mythical Greek goddess Gaia who personifies the co l. earth. ai gm It was first proposed by British scientist James Lovelock in his 1972 paper “Gaia as seen @ through the atmosphere.” 27 gn 1.2. Levels of Organisation of Ecology ha si The seven major ecological levels of organisations are: Organisms- They makes the basic unit of study in ecology. At each level, the biological unit has a specific structure and function. At this level, the form, physiology, behaviour, distribution and adaptations in relation to the environmental conditions are studied. Population- In ecology, a population is a group of individuals of the same species, inhabiting the same area, and functioning as a unit of biotic community. Biological Community- Biological/ Biotic community organisation results from interdependence and interactions amongst population of different species in a habitat. This is an assemblage of populations of plants, animals, bacteria and fungi that live in an area and interact with each other. (You will read about different types of interactions in detail further in this Chapter in topic 1.9 Biotic interactions) Ecosystem- The ecosystems are parts of nature where living organisms interact amongst themselves and with their physical environment. An ecosystem in composed of a biotic community, integrated with its physical environment through the exchange of energy and recycling of the nutrients. DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 5 www.visionias.in # 8468022022 ©Vision IAS  Ecosystems can be recognised as self- regulating and self-sustaining units of landscape, e.g., Student Notes: a pond or a forest. Landscape- A landscape is a unit of land with a natural boundary having a mosaic of patches, which generally represent different ecosystems. Biome- This is a large regional Biotic Potential unit characterized by a major The maximum rate at which a population can increase vegetation type and associated when resources are unlimited and environmental fauna found in a specific conditions are ideal is termed the population's biotic climate zone. The biome potential. includes all associated Each species will have a different biotic potential due to developing and modified variations in: communities occurring within o the species' reproductive span (how long an the same climatic region, e.g., individual is capable of reproducing) forest biomes, grassland and o the frequency of reproduction (how often an savanna biomes, desert biome, individual can reproduce) o "litter size" (how many offspring are born each etc. time) On a global scale, all the earth’s o survival rate (how many offspring survive to terrestrial biomes and aquatic reproductive age) systems constitute the Carrying Capacity biosphere. For a given region, carrying capacity is the maximum number of individuals of a given species that an area's (You will read in detail about resources can sustain indefinitely without significantly biomes in Chapter-2, Types of depleting or degrading those resources. Ecosystem) Biosphere- Biosphere is a part of earth where life can exist. It represents a highly integrated and interacting zone comprising of atmosphere (air), hydrosphere (water) and lithosphere (land). Biome and ecosystem are two different ecological concepts. Although they are closely related to each other, they are different from each other. m Biome Ecosystem co It is a large area of land with distinct climate It is the interaction of abiotic and biotic l. ai and plant and animal species. components between each other in a given area. gm @ It is a large geographical area. It is a small geographical area. 27 It is greatly influenced by climatic factors such It is not much influenced by the climatic factors gn as snow, ice, rainfall, temperature etc. like ice, snowfall, temperature etc. ha si It is a larger category of ecological units. It It is a part of biome made of biotic and abiotic contains multiple ecosystems within it. factors. As a biome is a collection of species it has a An ecosystem has a less diversity of plants and great diversity of plant and animal species. animals species than that of a biome as it is smaller in size. Some common examples of biomes include Some common examples include coral reefs, desert, tundra, grasslands, and tropical rain ponds, Gulf of Mexico etc. forests. Latitude has a great influence on a biome. An ecosystem is not affected by latitude. All the animals of a biome may not interact with All the animals and organisms of an ecosystem each other. interact with each other. DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 6 www.visionias.in # 8468022022 ©Vision IAS  Student Notes: m co l. ai gm @ 27 gn ha si DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 7 www.visionias.in # 8468022022 ©Vision IAS  Student Notes: IMPORTANT TERMS Ecotone: An ecotone is a zone of junction or a transition area between two biomes (diverse ecosystems). Ecotone is the zone where two communities meet and integrate. For e.g. the mangrove forests represent an ecotone between marine and terrestrial ecosystem. Other examples are grassland (between forest and desert), estuary (between fresh water and salt water) and riverbank or marshland (between dry and wet). Ecocline: Ecocline is a zone of gradual but continuous change from one ecosystem to another when there is no sharp boundary between the two in terms of species composition. Ecocline occurs across the environmental gradient (gradual change in abiotic factors such as altitude, temperature (thermocline), salinity (halocline), depth, etc.). Edge Effect – Edge Species Edge effect refers to the changes in population or community structures that occur at the boundary of two habitats (ecotone). Sometimes the number of species and the population density of some of the species in the ecotone is much greater than either community. This is called edge effect. The organisms which occur primarily or most abundantly in this zone are known as edge species. In the terrestrial ecosystems edge effect is especially applicable to birds. For example, the density of birds is greater in the ecotone between the forest and the desert. Ecological Niche Niche refers to the unique functional role and position of a species in its habitat or ecosystem. The functional characteristic of a species in its habitat is referred to as “niche” in that common habitat. In nature, many species occupy the same habitat, but they perform different functions: Habitat niche – where it lives, food niche – what is eats or decomposes & what species it competes with, Reproductive niche – how and when it reproduces, Physical & chemical niche – temperature, land shape, land slope, humidity & another requirement. Niche plays an important role in the conservation of organisms. If we have to conserve species in its native habitat, we should have knowledge about the niche requirements of the species. m co l. 1.3. Functions of an Ecosysytem ai gm @ Ecosystems are complex dynamic system, they perform following functions: 27 gn 1. Energy flow through food chain ha 2. Nutrient cycling (biogeochemical cycles) si 3. Ecological succession or ecosystem development 4. Homeostasis (or cybernetic) or feedback control mechanisms Ponds, lakes, meadows, marshlands, grasslands, deserts and forests are examples of natural ecosystem. Many of you have seen an aquarium; a garden or a lawn etc. in your neighborhood. These are man-made ecosystem 1.4. Energy Flow in an Ecosystem The cycle of energy is based on the flow of energy through different trophic levels in an ecosystem. Ecosystem is maintained by the cycling energy and nutrients obtained from different external sources. Sun is the primary source of energy for all ecosystems on Earth. Of the incident solar radiation less than 50 percent of it is photosynthetically active radiation (PAR). PAR, designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 8 www.visionias.in # 8468022022 ©Vision IAS Plants capture only 2-10 per cent of the PAR and this small amount of energy sustains the entire Student Notes: living world. The energy of sunlight fixed in food production by green plants is passed through the ecosystem by food chains and webs from one trophic level to the next. In this way, energy flows through the ecosystem. TROPHIC LEVEL The trophic level of an organism is the position it occupies in a food chain. The trophic level is the number of steps an organism is from start of the chain. A given organism may occupy more than one trophic level simultaneously. One must remember that the trophic level represents a functional level, not a species as such. A given species may occupy more than one trophic level in the same ecosystem at the same time; for example, a sparrow is a primary consumer when it eats seeds, fruits, peas, and a secondary consumer when it eats insects and worms. At the first trophic level, primary producers use solar energy to produce organic material through photosynthesis. The herbivores at the second trophic level use the plants as food which gives them energy. m co A large part of this energy is used up for the metabolic functions of these animals such as l. ai gm breathing, digesting food, supporting growth of tissues, maintaining blood circulation and @ body temperature. 27 The carnivores at the next trophic level feed on the herbivores and derive energy for their gn ha sustenance and growth. If large predators are present, they represent still higher trophic si level and they feed on carnivores to get energy. DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 9 www.visionias.in # 8468022022 ©Vision IAS 1.5. Food Chain Student Notes: 1.5.1. Definition The order of living organisms in a community in which one organism consumes other and is itself consumed by another organism to transfer energy is called a food chain. Food chain is also defined as “a chain of organisms, existing in any natural community, through which energy is transferred”. Every living being irrespective of their size and habitat, from the tiniest algae to giant blue whales, need food to survive. m co l. ai gm @ 27 gn Food chain is structured differently for different species in different ecosystems. Each food chain ha is the vital pathway for energy and nutrients to follow through the ecosystem. si 1.5.2. Types of Food Chain There are two types of food chains: Grazing food chain, beginning with autotrophs. In this, energy and nutrients move from plants to the herbivores consuming them, and to the carnivores or omnivores preying upon the herbivores. Detrital food chain, beginning with dead organic matter. In a detrital food chain, dead organic matter of plants and animals is broken down by decomposers, e.g., bacteria and fungi, and moves to detritivores and then carnivores. 1.6. Food Web The word ‘web’ means network. Food web can be defined as ‘a network of interconnected food chains so as to form a number of feeding relationships amongst different organism of a biotic community. DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 10 www.visionias.in # 8468022022 ©Vision IAS A food chain cannot stand isolated in an Student Notes: ecosystem. The same food resource may be a part of more than one chain. This is possible when the resource is at the lower tropic level. A food web comprises all the food chains in a single ecosystem. It is essential to know that each living thing in an ecosystem is a part of multiple food chains.(As illustrated in the diagram) A single food chain is the single possible path that energy and nutrients may make while passing through the ecosystem. All the interconnected and overlapping food chains in an ecosystem make up a food web. Food webs are significant tools in understanding that plants are the foundation of all ecosystem and food chains, sustaining life by providing nourishment and oxygen needed for survival and reproduction. The food web provides stability to the ecosystem. 10% rule The important point to note is that the amount of energy decreases at successive trophic levels. The number of trophic levels in the grazing food chain is restricted as the transfer of energy follows 10 per cent law – only 10 per cent of the energy is transferred to each trophic level from the lower trophic level. 1.7. Ecological Pyramid 1.7.1. Definition An ecological pyramid is a graphical representation of the relationship between different m organisms in an ecosystem. co l. ai Each of the bars that make up the pyramid represents a different trophic level, and their order, gm @ which is based on who eats whom, represents the flow of energy. 27 gn 1.7.2. Types of Ecological Pyramids ha si Pyramid of Biomass As the name suggests, the Biomass Pyramids show the amount of biomass (living or organic matter present in an organism) present per unit area at each trophic level. It is drawn with the producers at the base and the top carnivores at the top. Pyramid of biomass is generally ascertained by gathering all organisms occupying each trophic level separately and measuring their dry weight. Each trophic level has a certain mass of living material at a particular time called standing crop, which is measured as the mass of living organisms (biomass) or the number in a unit area. Upright Pyramid of Biomass Ecosystems found on land mostly have pyramids of biomass with large base of primary producers with smaller trophic level perched on top, hence the upright pyramid of biomass. DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 11 www.visionias.in # 8468022022 ©Vision IAS  Student Notes: The biomass of autotrophs or producers is at the maximum. The biomass of next trophic level, i.e. primary consumers is less than the producers. Similarly, the other consumers such as secondary and tertiary consumers are comparatively less than its lower level respectively. The top of the pyramid has very less amount of biomass. Inverted Pyramid of Biomass On the other hand, a reverse pyramidal structure is found in most aquatic ecosystems. Here, the pyramid of biomass may assume an inverted pattern. This is because in a water body, the producers are tiny phytoplankton that grow and reproduce rapidly. In this condition, the pyramid of biomass has a small base, with the producer biomass at the base providing support to consumer biomass of large weight. Hence, it assumes an inverted shape. m co l. ai gm @ 27 gn ha si Pyramid of Numbers It is the graphic representation of number of individuals per unit area of various trophic levels. Large number of producers tends to form the base whereas lower number of top predators or carnivores occupies the top. The shape of the pyramid of numbers varies from ecosystem to ecosystem. For example, in an aquatic ecosystem or grassland areas, autotrophs or producers are present in large number per unit area. The producers support a lesser number of herbivores, which in turn supports fewer carnivores. Upright Pyramid of Numbers In upright pyramid of numbers, the number of individuals decreases from the lower level to the higher level. This type of pyramid is usually found in the grassland ecosystem and the DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 12 www.visionias.in # 8468022022 ©Vision IAS  pond ecosystem. The grass in a grassland ecosystem occupies the lowest trophic level Student Notes: because of its abundance. Inverted Pyramid of Numbers Here, the number of individuals increases from the lower level to the higher trophic level. For example, the tree ecosystem. Pyramid of Energy It is a graphical structure representing the flow of energy through each trophic level of a food chain over a fixed part of the natural environment. An energy pyramid represents the amount of energy at each trophic level and loss of energy at each is transferred to another trophic level. m Energy pyramid, sometimes called trophic pyramid or ecological pyramid, is used in co l. quantifying the energy transfer from one organism to another along the food chain. ai gm @ 27 gn ha si Energy decreases as one move through the trophic levels from the bottom to the top of the pyramid. Thus, the energy pyramid is always upward. DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 13 www.visionias.in # 8468022022 ©Vision IAS 1.8. Ecological Productivity Student Notes: 1.8.1. Definition Ecological productivity refers to the primary fixation of solar energy by plants and the subsequent use of that fixed energy by plant-eating herbivores, animal-eating carnivores, and the detritivores that feed upon dead biomass. Ecologists refer to the productivity of green plants as primary productivity. Gross primary productivity is the total amount of energy that is fixed by plants, while net primary productivity is smaller because it is adjusted for energy losses required to support plant respiration. If the net primary productivity of green plants in an ecosystem is positive, then the biomass of vegetation is increasing over time. Gross Primary productivity= Net Primary Productivity + Energy loss due to respiration Gross and net secondary productivities refer to herbivorous animals, while tertiary productivities refer to carnivores. Different productivity of various ecosystems Because of differences in the availabilities of solar radiation, water, and nutrients, the world’s ecosystems differ greatly in their Ecological Productivity. ORDER OF PRODUCTIVITY m co l. ai gm @ 27 gn ha si 1.9. Biological Interaction These are the manner in which species interact with each other. These interactions can be inter- specific (interactions with different species) or intra-specific (interactions between same species). DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 14 www.visionias.in # 8468022022 ©Vision IAS 1.9.1. Types of Biotic Interactions in a Food Web Student Notes: ‘0’ is no effect; ‘–’ is detrimental; ‘+’ is beneficial. Type of Species Effect Comments interaction 1 2 Negative Interactions The bread mould fungi Penicillium produce penicillin an antibiotic substance which One species is inhibited inhibits the growth of a variety of bacteria. Amensalism – 0 while the other species A large tree shades a small plant, retarding the is unaffected. growth of the small plant. The small plant has no effect on the large tree. Predators like leopards, tigers and cheetahs use speed, teeth and claws to hunt and kill One species (predator) their prey. benefits while the Predation + – Predators help in maintaining species second species (prey) is diversity in a community, by reducing the harmed and inhibited. intensity of competition among competing prey species. Parasitism involves parasite living in or on another living species called the host. The parasite gets its nourishment and often shelter from its host. Beneficial to one species Tap worm, roundworm, malarial parasite, (parasite) and harmful Parasitism + – many bacteria, fungi, and viruses are common to the other species parasites of humans. (host). The female mosquito is not considered a parasite, although it needs our blood for reproduction. Why? Because it doesn’t live on the host. m co l. ai Competition occurs when two populations or gm species, both need a vital resource that is in @ short supply. 27 gn Adversely affects both Woodpeckers and squirrels often compete for Competition – – ha species. nesting rights in the same holes and spaces in si trees, while the lions and cheetahs of the African savanna compete for the same antelope and gazelle prey. Positive Associations Suckerfish often attaches to a shark. This helps the suckerfish get protection, a free ride One species (the as well as a meal from the leftover of the commensal) benefits, shark’s meal. The shark does not, however, Commensalism + 0 while the other species get any benefit nor is it adversely affected by (the host) is neither this association. harmed nor inhibited Another example of commensalisms is the relationship between trees and epiphytic plants. Interaction is favourable Sea anemone gets attached to the shell Mutualism + + to both species of hermit crabs for the benefit of transport DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 15 www.visionias.in # 8468022022 ©Vision IAS  and obtaining new food while the anemone Student Notes: provides camouflage and protection utilizing its stinging cells to the hermit crab. Some mutualisms are so intimate that the interacting species can no longer live without each other as they depend totally on each other to survive. Such close associations are called symbiosis (symbiosis is intense mutualism – E.g. coral and zooxanthellae). Neutral Interactions Neither species affects Neutralism 0 0 True neutralism is extremely unlikely. the other 1.10. Ecological Succession Ecological succession is the process by which the structure of biological community evolves over time. 1.10.1. Types of Succession Primary succession –It occurs in essentially lifeless areas—regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. Secondary succession –It occurs in areas where a community that previously existed has been removed; it is typified by smaller-scale disturbances that do not eliminate all life and nutrients from the environment. m co l. ai gm @ 27 gn ha si In ecological terminology, the developmental stages of a community are known seral stages and the final stage as the climax community. The entire series of communities that is characteristic of a given site is called a sere. DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 16 www.visionias.in # 8468022022 ©Vision IAS  Student Notes: Other prominent types of Ecological Succession: Autotrophic Succession Autotrophic Succession is characterised by early and continued dominance of autotrophic organisms like green plants. It begins in a predominantly inorganic environment and the energy flow is maintained indefinitely. Allogeneic Succession In Allogeneic Succession, the replacement of the existing community is caused largely by any other external condition and not by the existing organisms. Autogenic Succession Autogenic Succession refers to that type when the community itself, as a result of its reactions with the environment, modifies its own environment and thus causing its own replacement by new communities. Hydrarch Succession Plant succession starting on relatively shallow water, such as ponds and lakes, and culminating in a mature forest. Xerarch Succession: Plant succession starting on bare ground or rock and culminating in a mature climax forest. The pioneer species, such as lichens and mosses, result in the gradual accumulation of soil m 1.11. Biogeochemical Cycles co l. ai All elements in the earth are recycled time and again. The major elements such as oxygen, gm carbon, nitrogen, phosphorous, and sulphur are essential ingredients that make up organisms. @ 27 gn Biogeochemical cycles refer to the flow of such chemical elements and compounds between ha organisms and the physical environment. Chemicals taken in by organisms are passed through si the food chain and come back to the soil, air, and water through mechanisms such as respiration, excretion, and decomposition. Biogeochemical cycles can be either gaseous (which the reservoir pool is the atmosphere) or sedimentary (reservoir pool is the Earth's crust) Gaseous Biogeochemical Cycles o Carbon Cycle o Nitrogen Cycle o Water Cycle o Oxygen Cycle Sedimentary Biogeochemical Cycle o Phosphorus Cycle o Sulphur Cycle DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 17 www.visionias.in # 8468022022 ©Vision IAS 1.11.1. Carbon Cycle Student Notes: Carbon enters into the living world in the form of carbon dioxide through the process of photosynthesis as carbohydrates. These organic compounds (food) are then passed from the producers to the consumers (herbivores & carnivores). This carbon is finally returned to the surrounding medium by the process of respiration or decomposition of plants and animals by the decomposers. Carbon is also recycled during the burning of fossil fuels. 1.11.2. Nitrogen Cycle Nitrogen is present in the atmosphere in an elemental form and as such it cannot be utilized by living organisms. This elemental form of nitrogen is converted into combined state with elements such as H, C, O by certain bacteria, so that it can be readily used by the plants. Nitrogen fixing Bacteria- Some bacteria can turn Nitrogen in to ammonia by the process known as NITROGEN FIXATION. Examples-Azotobacter, Achaea etc. Denitrifying Bacteria-These bacteria metabolize nitrogenous compounds using various enzymes turning nitrogen oxides back to nitrogen gas or nitrous oxide. m co l. ai gm @ 27 gn ha si Nitrogen is being continuously expelled into the air by the action of microorganisms such as denitrifying bacteria and finally returned to the cycle through the action of lightening and electrification. DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 18 www.visionias.in # 8468022022 ©Vision IAS  Student Notes: Water Cycle o The evaporation of water from ocean, rivers, lakes, and transpiring plants takes water in the form of vapors to the atmosphere. o This vaporized water subsequently cools and condenses to form cloud and water. This cooled water vapor ultimately returns to the earth as rain and snow, completing the cycle. m co l. ai OXYGEN CYCLE gm o The oxygen cycle is the cycle that helps move oxygen through the three main regions of @ 27 the Earth, the Atmosphere, the Biosphere, and the Lithosphere. The Atmosphere is of gn course the region of gases that lies above the Earth’s surface and it is one of the largest ha reservoirs of free oxygen on earth. si o The Biosphere is the sum of all the Earth’s ecosystems. This also has some free oxygen produced from photosynthesis and other life processes. o The largest reservoir of oxygen is the lithosphere. Most of this oxygen is not on its own or free moving but part of chemical compounds such as silicates and oxides DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 19 www.visionias.in # 8468022022 ©Vision IAS  SULPHUR CYCLE Student Notes: o Sulphur occurs in all living matter as a component of certain amino acids. It is abundant in the soil in proteins and, through a series of microbial transformations, ends up as sulphates usable by plants. o Sulphur-containing proteins are degraded into their constituent amino acids by the action of a variety of soil organisms. The sulphur of the amino acids is converted to hydrogen sulphide (H2S) by another series of soil microbes. In the presence of oxygen, H2S is converted to sulphur and then to sulphate by sulphur bacteria. Eventually the sulphate becomes H2S. PHOSPORUS CYCLE o It is in these rocks where the phosphorus cycle begins. When it rains, phosphates are removed from the rocks (via weathering) and are distributed throughout both soils and water. o Plants take up the phosphate ions from the soil. The phosphates then moves from plants to animals when herbivores eat plants and carnivores eat plants or herbivores. o The phosphates absorbed by animal tissue through consumption eventually returns to the soil through the excretion of urine and faeces, as well as from the final decomposition of plants and animals after death. m o IN AQUATIC ECOSYSTEM- co l. ü The same process occurs within the aquatic ecosystem. Phosphorus is not highly ai gm soluble in water, thus binds tightly to molecules in soil; therefore it mostly reaches @ waters by traveling with runoff soil particles. 27 gn ü Phosphates also enter waterways through fertilizer runoff, sewage seepage, natural ha mineral deposits, and wastes from other industrial processes. si ü These phosphates tend to settle on ocean floors and lake bottoms. As sediments are stirred up, phosphates may re-enter the phosphorus cycle. Water plants take up the waterborne phosphate which then travels up through successive stages of the aquatic food chain. DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 20 www.visionias.in # 8468022022 ©Vision IAS 1.12. Ecosystem Services Student Notes: Ecosystem services are the benefits people obtain from ecosystems. These include provisioning, regulating, and cultural services that directly affect people and supporting services needed to maintain the other services. The Millennium Ecosystem Assessment (MA) was initiated in 2001 by United Nations. The objective of the MA was to assess the consequences of ecosystem change for human well-being, the scientific basis for action needed to enhance the conservation and sustainable use of those systems and their contribution to human well-being. m co l. ai gm @ 27 gn ha si Examples of some plant resources Medicinal herbs: Chamomile, Echinacea, Feverfew, Garlic, Ginseng, Goldenseal, Valerian etc. Fiber Yielding Plants: Himalayan Nettle, Sisal Hemp, Jute, Cotton etc. Natural Capital It includes those elements of the nature that provide valuable goods and services to humans, such as the stock of forests, food, clean air, water, land, minerals, etc. It incorporates a broad perspective on the set of services provided by ecosystems assets. It is essential for economic growth, employment, and, ultimately, prosperity. DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 21 www.visionias.in # 8468022022 ©Vision IAS  Natural Capital Accounting, or environmental-economic accounting Student Notes: It is a tool that can help to gain an understanding of the interaction between the economy and the environment. It can be used to measure the state of ecosystems, flows of ecosystem services as well as changes in stocks and flows of natural resources in relation to economic changes. System of Environmental-Economic Accounting (SEEA) It is a statistical system that brings together economic and environmental information into a common framework to measure the condition of the environment, the contribution of the environment to the economy and the impact of the economy on the environment. Natural Capital Accounting and Valuation of Ecosystem Services The United Nations Statistics Division, UNEP, the Secretariat of the Convention on Biological Diversity, and the European Union have launched this project. The project is funded by the European Union, aims to assist the five participating partner countries, namely Brazil, China, India, Mexico and South Africa, to advance the knowledge agenda on environmental and ecosystem accounting. The project review policy demands, data availability and measurement practices in order to advance and mainstream natural capital accounting and initiate pilot ecosystem accounts in each of the five strategic partner countries. The Economics of Environment and Biodiversity (TEEB) In 2007, G8+5 countries proposed to initiate the process of analyzing the global economic benefit of biological diversity, the costs of the loss of biodiversity and the failure to take protective measures versus the costs of effective conservation. In response to this, a global study was conducted by Germany and the European Commission under Pavan Sukhdev which led to the establishment of TEEB. Based in Geneva, Switzerland, at the International Environment House, the TEEB office is hosted by the UNEP. TEEB is a global initiative focused on “making nature’s values visible”. Its principal objective is to mainstream the values of biodiversity and ecosystem services into decision-making at all levels. In October 2010 it released its report " Mainstreaming the Economics of Nature: A Synthesis of the Approach, Conclusions and Recommendations of TEEB " and launched the Bank of Natural Capital to communicate its findings to the general public. It is guided by three core principles: o Recognizing value in ecosystems can sometimes ensure conservation and sustainable use. e.g. m co the existence of sacred groves in some cultures has helped to protect natural areas and the l. biodiversity they contain. ai gm o Demonstrating value in economic terms is often useful for policy makers and others such as @ business in reaching decisions that consider the full costs and benefits of an ecosystem. E.g. By 27 including the costs and benefits of conserving the ecosystem services provided by wetlands in gn ha controlling floods compared to building flood defences. si o Capturing value involves the introduction of mechanisms that incorporate the values of ecosystems into decisionmaking through incentives and price signals. This can include payments for ecosystem services, reforming environmentally harmful subsidies or introducing tax breaks for conservation. IPBES Global Assessment Report The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) is an independent intergovernmental body established in 2012 with now over 130 member states around the world. The report by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) is the most comprehensive scientific evaluation ever made of the state of our nature, and gives a detailed account of health of the species that inhabit this earth, and the condition of habitats that they live in and depend upon. It is the first intergovernmental Report of its kind and builds on the landmark Millennium Ecosystem Assessment of 2005, introducing innovative ways of evaluating evidence. The Report concluded that the second-fastest mass extinction event in planetary history is underway; the current rate of extinction is 100 to 1000 times greater than historical background rates. Over one million species are at risk of extinction within the next few decades. DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 22 www.visionias.in # 8468022022 ©Vision IAS  The Report highlighted the importance of indigenous community in conservation. It notes, Student Notes: “Nature managed by Indigenous Peoples and Local Communities is under increasing pressure but is generally declining less rapidly than in other lands.” This is significant since “at least” a quarter of the world’s land area is “traditionally owned, managed, used or occupied by indigenous peoples”. 1.13. UPSC Previous Years Question Mains 1. What are the consequences of spreading of ‘Dead Zones’ on marine ecosystem? (2018) (10 marks) 2. Define the concept of carrying capacity of an ecosystem as relevant to an environment. Explain how understanding this concept is vital while planning for sustainable development of a region. (2019)(15 marks) Prelims 1. With reference to food chains in ecosystems, consider the following statements : (2013) 1. A food chain illustrates the order in which a chain of organisms feed upon each other. 2. Food chains are found within the populations of a species. 3. A food chain illustrates the numbers of each organism which are eaten by others. Which of the statements given above is / are correct? (a) 1 only (b) 1 and 2 only (c) 1, 2 and 3 (d) None Answer: (a) 2. Which one of the following terms describes not only the physical space occupied by an organism, but also its functional role in the community of organisms? (2013) (a) Ecotone (b) Ecological niche (c) Habitat (d) Home range m Answer: (b) co l. ai gm 3. With reference to the food chains in ecosystems, which of the following kinds of organism @ is / are known as decomposer organism/organisms? (2013) 27 1. Virus gn ha 2. Fungi si 3. Bacteria Select the correct answer using the codes given below. (a) 1 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2 and 3 Answer: (b) 4. Which of the following adds/add carbon dioxide to the carbon cycle on the planet Earth? (2014) 1. Volcanic action 2. Respiration 3. Photosynthesis 4. Decay of organic matter Select the correct answer using the code given below. (a) 1 and 3 only (b) 2 only (c) 1, 2 and 4 only (d) 1, 2, 3 and 4 Answer: (c) DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 23 www.visionias.in # 8468022022 ©Vision IAS 5. Which one of the following is the correct sequence of a food chain? (2014) Student Notes: (a) Diatoms-Crustaceans-Herrings (b) Crustaceans-Diatoms-Herrings (c) Diatoms-Herrings-Crustaceans (d) Crustaceans-Herrings-Diatoms Answer: (a) 6. Consider the following statements (2019) 1. Agricultural soils release nitrogen oxides into environment. 2. Cattle release ammonia into environment. 3. Poultry industry releases reactive nitrogen compounds into the environment. Which of the statements given above is/are correct? (a) 1 and 3 only (b) 2 and 3 only (c) 2 only (d) 1, 2 and 3 Answer: d 1.14. Vision IAS Previous Years Questions 1. Ecosystem services are the direct and indirect contributions of ecosystems to human well-being. In this context, distinguish between supporting, provisioning, regulating and cultural services provided by ecosystems. Approach: Briefly discuss the importance of ecosystem services for human well-being. Differentiate between supporting, provisioning, regulating and cultural services provided by ecosystems. Conclude accordingly. Answer: Ecosystem services are critical for human well-being as they provide indispensable services at the local, regional and global scales, such as food production, water purification, flood protection and climate-change mitigation. According to The Economics of Ecosystems and Biodiversity (TEEB), ecosystem services can be categorized in following four main types: m co Supporting services are the ecosystem services that are necessary for the production l. ai gm of all other ecosystem services. These includes- @ o Habitats for species: Habitats provide everything that an individual plant or 27 animal needs to survive like food, water, and shelter. gn ha o Maintenance of genetic diversity: It distinguishes different breeds or races from si each other thus providing the basis for locally well-adapted cultivars and a gene pool for further developing commercial crops and livestock. Provisioning services are the ecosystem services that describe the material or energy outputs from ecosystems. Water, food, wood and other goods are some of the material benefits people obtain from ecosystems called ´provisioning services´. Many provisioning services are traded in markets. However, in many regions, rural households also directly depend on provisioning services for their livelihoods. They include: o Food: Ecosystem provides conditions for growing foods. o Raw materials: It provides materials for construction and fuel including wood, biofuels and plant oils. o Fresh water: Ecosystem regulates the flow and purification of water. o Medicinal resources: It provides many plants for traditional medicines and provides raw materials for the pharmaceutical industry. Regulating services are defined as the benefits obtained from the regulation of ecosystem processes. Maintaining the quality of air and soil, providing flood and DELHI | JAIPUR | PUNE | HYDERABAD | AHMEDABAD | LUCKNOW | CHANDIGARH | GUWAHATI 24 www.visionias.in # 8468022022 ©Vision IAS  disease control, or pollinating crops are some of the ‘regulating services' provided by Student Notes: ecosystems. These services include: o Climate regulation: Trees provide shade whilst forests influence rainfall and water availability both locally and regionally. o Carbon sequestration: As trees and plants grow, they remove carbon dioxide from the atmosphere and effectively lock it away in their tissues. o Natural hazard regulation: Ecosystems and living organisms create buffers against natural disasters, thereby preventing possible damage. o Water purification and waste management: Ecosystems such as wetlands filter both human and animal waste and act as a natural buffer to the surrounding environment. o Other important services include pollination and pest control. Cultural services include non-material benefits that people obtain from ecosystems. Cultural services are deeply interconnected with each other and often connected to provisioning and regulating services: Small scale fishing is not only about food and income, but also about fishers’ way of life. These are: o Spiritual enrichment: In many parts of the world, natural features such as specific forests, caves, mountains etc. are considered sacred or have a religious meaning. o Intellectual development: Language, knowledge and the natural environment have been intimately related throughout human history. Biodiversity, ecosystems and natural landscapes have been the source of inspiration for much of our art, culture and increasingly for science. o Various kinds of tourism services: These provide considerable economic benefits and are a vital source of income for many countries. In spite of the ecological, cultural and economic importance of these services, ecosystems are still being degraded at an unprecedented scale. It is primarily because the value of ecosystems to human welfare is still being underestimated and not fully recognized. In this context, Natural Capital Accounting is a key concept that recognizes the economic cost of natural capital. m co l. ai gm 2. Explain the concept of biogeochemical cycles and their significance in the functioning @ 27 of ecosystems. What are the challenges that they face because of anthropogenic gn factors? ha si Approach: Introduce the answer by explaining the concept of biogeochemical cycles. Explain its significance in the functioning of the ecosystem. Conclude the answer by enlisting challenges faced by these cycles due to human interventions. Answer: A biogeochemical cycle is one of several natural cycles, in which conserved matter moves through the biotic and abiotic components of an ecosystem. The main chemical elements that are cycled are: carbon (C), hydrogen (H), nitrogen (N), oxygen (O), phosphorous (P) and sulfur (S). Important biogeochemical cycles are : Water Cycle: All of the water that falls on the land does not immediately flow back into the sea. Some of it seeps into the soil and becomes part of the underground reservoir of fresh-water. Some of this underground water finds its way to the surface DELHI | J