Environmental Studies (VAC00006) Class Notes - Brainware University - PDF

Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 Study Material (Environmental Studies and VAC00006) ________________________________________________________________________________________ Table of Contents Module-II: Ecosystems and Biodiversity, Conservation [7H] ⮚ Ecosystems Definition and concept of Ecosystem. Structure of ecosystem (biotic and abiotic components); Functions of Ecosystem: Physical (energy flow), Biological (food chains, food web, ecological succession), and Biogeochemical (nutrient cycling) processes. Concepts of productivity, ecological pyramids and homeostasis. Types of Ecosystems: Forest, Grassland, Desert, Aquatic (ponds, rivers, oceans); importance and threats with relevant examples from India ⮚ Biodiversity, Conservation Definition of Biodiversity; Levels of biological diversity: genetic, species and ecosystem diversity. India as a mega-biodiversity nation; Biogeographic zones of India; Biodiversity hotspots; Endemic and endangered species of India; IUCN Red list criteria and categories Threats to biodiversity: Habitat loss, degradation, and fragmentation; Poaching of wildlife; Man-wildlife conflicts; Biological invasion with emphasis on Indian biodiversity. Biodiversity conservation strategies: in-situ and ex-situ methods of conservation; National Parks, Wildlife Sanctuaries, and Biosphere reserves; Keystone, Flagship, Umbrella, and Indicator species. Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 ECOSYSTEM CONCEPT OF ECOSYSTEM The term ecosystem was proposed by A.G. Tansley in 1935, who defined it as ‘the system resulting from the integration of all the living and non-living factors of the environment’. Thus, ecosystem consider not only the organism but also the whole complex of physical factors forming the environment. ‘Eco’ implies the ‘environment’ and ‘system’ implies an interacting and interdependent complex. Different types of ecosystems of nature, constituting the giant ecosystem-the biosphere. It categorized as and Man-made Ecosystem. 1. Natural Ecosystem: These operate by themselves under natural conditions without any major interference by man. Based upon the particular kind of habitat, these are further divided as: (i) Terrestrial ecosystem (forest, grassland, desert etc.) (ii) Aquatic ecosystem (water-fresh and marine). Fresh water is divided as Lotic (running water as spring, stream, rivers etc.) and lentic (standing water as lake, pond, etc.). Marine, which include deep bodies as an ocean or shallow ones as a sea or estuary. 2. Man-made ecosystem: These are maintained artificially by humans where, by addition of energy and planned manipulations, natural balance is disturbed regularly. For example, croplands like maize, wheat, rice-field etc. where man tries to control the biotic community as well as the physio-chemical environment, are artificial ecosystems. Ecosystem Structure and Function: The ecosystem is the structural and functional unit of ecology where the living organisms interact with each other and the surrounding environment. In other words, an ecosystem is a chain of interaction between organisms and their environment. The term “Ecosystem” was first coined by A.G. Tansley, an English botanist, in 1935. Read on to explore the structure, components, types and functions of the ecosystem in the ecosystem notes provided below. Types of Ecosystem: An ecosystem can be as small as an oasis in a desert, or as big as an ocean, spanning thousands of miles. There are two types of ecosystem: Terrestrial Ecosystem Aquatic Ecosystem Terrestrial Ecosystems: Terrestrial ecosystems are exclusively land-based ecosystems. There are different types of terrestrial ecosystems distributed around various geological zones. They are as follows: 1. Forest Ecosystems Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 2. Grassland Ecosystems 3. Tundra Ecosystems 4. Desert Ecosystem Forest Ecosystem: A forest ecosystem consists of several plants, animals and microorganisms that live in coordination with the abiotic factors of the environment. Forests help in maintaining the temperature of the earth and are the major carbon sink. Grassland Ecosystem: In a grassland ecosystem, the vegetation is dominated by grasses and herbs. Temperate grasslands, savanna grasslands are some of the examples of grassland ecosystems. Tundra Ecosystem: Tundra ecosystems are devoid of trees and are found in cold climates or where rainfall is scarce. These are covered with snow for most of the year. The ecosystem in the Arctic or mountain tops is tundra type. Desert Ecosystem: Deserts are found throughout the world. These are regions with very little rainfall. The days are hot and the nights are cold. Aquatic Ecosystem: Aquatic ecosystems are ecosystems present in a body of water. These can be further divided into two types, namely: 1. Freshwater Ecosystem 2. Marine Ecosystem Freshwater Ecosystem: The freshwater ecosystem is an aquatic ecosystem that includes lakes, ponds, rivers, streams and wetlands. These have no salt content in contrast with the marine ecosystem. Marine Ecosystem: The marine ecosystem includes seas and oceans. These have a more substantial salt content and greater biodiversity in comparison to the freshwater ecosystem. Structure of the Ecosystem: The structure of an ecosystem is characterized by the organization of both biotic and abiotic components. This includes the distribution of energy in our environment. It also includes the climatic conditions prevailing in that particular environment. The structure of an ecosystem can be split into two main components, namely: Ecosystem Abiotic Factors Biotic Factors Producer Consumer Decomposer Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 Sunlight, Autotrophs Primary Secondary Tertiary Micro- Nutrient and (Herbivores) (Pri. Carnivore) (Sec. Organisms Minerals, carnivores) Climate etc. Biotic Components Abiotic Components The biotic and abiotic components are interrelated in an ecosystem. It is an open system where the energy and components can flow throughout the boundaries Abiotic Components Abiotic components are the non-living component of an ecosystem. It includes air, water, soil minerals, sunlight, temperature, nutrients, wind, altitude, turbidity, etc. Functions of Ecosystem: The functions of the ecosystem are as follows: 1. It regulates the essential ecological processes, supports life systems and renders stability. 2. It is also responsible for the cycling of nutrients between biotic and abiotic components. 3. It maintains a balance among the various trophic levels in the ecosystem. 4. It cycles the minerals through the biosphere. 5. The abiotic components help in the synthesis of organic components that involves the exchange of energy. Food Chain A food chain is a linear network of links in a food web starting from producer organisms (such as grass or trees which use radiation from the Sun to make their food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), detrivores (like earthworms or woodlice), or decomposer species (such as fungi or bacteria). A food chain also shows how organisms are related to each other by the food they eat. Each level of a food chain represents a different trophic level. A food chain differs from a food web because the complex network of different animals' feeding relations are aggregated and the chain only follows a direct, linear pathway of one animal at a time. Natural interconnections between food chains make it a food web. The sun is the ultimate source of energy on earth. It provides the energy required for all plant life. The plants utilize this energy for the process of photosynthesis, which is used to synthesize their food. During this biological process, light energy is converted into chemical energy and is passed on through successive levels. The flow of energy from a producer, to a consumer and eventually, to an apex predator or a detrivore is called the food chain. Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 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 utilized again by the producers. A classic example of a food chain in an ecosystem The food chain is an ideal representation of flow of energy in the ecosystem. In the food chain, the plants or producers are consumed by only the primary consumers, primary consumers are fed by only the secondary consumers and soon. The producers that are capable of producing their own food are called autotrophs. Any food chain consists of three main trophic levels, viz., producers, consumers and decomposers. The energy efficiency of each trophic level is very low. Hence, shorter the food chain greater the accessibility of food. The typical food chain in a ground ecosystem proceeds as grass, mouse, snake, hawk (Hawks are birds of prey of the family Accipitridae). Food webs are more complex and are interrelated at different trophic levels. Organisms have more than one choice for food and hence can survive better. Hawks don’t restrict their food to snakes, snakes eat animals other than mice, and mice eat grass as well as grasshoppers, and so on. A more realistic illustration of feeding habits in an ecosystem is called a food web. Charles Elton presented the food web concept in 1927, which he termed as food cycle. Charles Elton described the concept of food web as: The carnivore animals prey on the herbivores. These herbivores obtain the energy from sunlight. The later carnivores may also be preyed upon by other carnivores. Until a reach where an animal has no enemies it forms a terminus on this food cycle. Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 There are chains of animals that are related together by food, and all are dependent on plants in the long run. This is termed as a food chain and all the food chains in a community is known as the food web. A food web is a graphical depiction of feeding connections among species of an ecological community. Food web includes food chains of a particular ecosystem. The food web is an illustration of various techniques of feeding that links the ecosystem. The food web also explains the energy flow through species of a community as a result of their feeding relationships. All the food chains are interconnected and overlapping within an ecosystem and they constitute a food web. In a natural environment or an ecosystem, the relationships between the food chains are interrelated. These relationships are very complex, as one organism may be a part of multiple food chains. Hence, a web-like structure is formed in place of a linear food chain. The web-like structure if formed with the interlinked food chain and such matrix that is interconnected is known as a food web. Food webs are an inseparable part of an ecosystem; these food webs permit an organism to obtain food from more than one type of organism of the lower trophic level. Every living being is responsible and is a part of multiple food chains in the given ecosystem. Ecological pyramids ▪ The trophic levels of different organisms based on their ecological position as producer to final consumer is represented by an ecological pyramid. ▪ The food producer is present at the base of the pyramid and on the top. ▪ Other consumer trophic levels are present in between. ▪ The pyramid includes a number of horizontal bars presenting specific trophic levels. ▪ The length of each bar stands for the total number of individuals or biomass or energy at each trophic level in an ecosystem. ▪ An ecological pyramid is a graphical representation outlined to show the biomass or bio productivity at each trophic level in a given ecosystem. ▪ These are trophic pyramids, energy pyramids, or sometimes food pyramids. ▪ Biomass is the quantity of living or organic matter present in an organism. ▪ Biomass pyramids represent the amount of biomass, and how much of it is present in the organisms at each trophic level. ▪ The productivity pyramids show the production or turnover in biomass. ▪ Ecological pyramids initiate with producers on the bottom such as green plants and proceed through the various trophic levels such as herbivores that feed on Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 plants, then carnivores that feed on herbivores, then carnivores that feed those carnivores, and so on. ▪ The highest level is shown at the top of the chain. ▪ An ecological pyramid of biomass represents the relationship between biomass and trophic level by quantifying the biomass present at each trophic level of an ecological community at a particular time. ▪ It is a graphical representation of biomass present per unit area in different trophic levels. ▪ Flow of energy through the food chain will be in a predictable way, entering at the base of the food chain, by photosynthesis in primary producers, and then moving up the food chain to higher trophic levels. ▪ The transfer of energy from one trophic level to the next is not efficient. ▪ It may also be useful and productive to analyze how the number and biomass of organisms differs across trophic levels. ▪ Both the number and biomass of organisms at each trophic level should be affected by the amount of energy joining that trophic level. ▪ When there is a direct correlation between energy, numbers, and biomass then biomass pyramids and numbers pyramids will be formed. ▪ However, the relationship between energy, biomass, and number can be complex by the growth form and size of organisms and ecological relationships occurring among trophic levels. Types of pyramids: ▪ The ecological pyramids are of three categories: 1. Pyramid of Numbers 2.Pyramid of Biomass 3. Pyramid of Energy or Productivity Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 1. Pyramid of numbers: ▪ Pyramid of numbers represents the population of trophic level as the total number of individuals of different species present at each trophic level. ▪ Pyramids of numbers may be upright and or completely inverted depending upon count of individuals present and so. ▪ The pyramid of numbers does not completely define the trophic structure for an ecosystem as it is very tough to count all the organisms present there. ▪ Pyramid of number- upright: grassland ecosystem ▪ In this pyramid, the number of individuals is decreased from lower level to higher trophic level. ▪ The examples of pyramids of numbers are the Grassland ecosystem and pond ecosystem. ▪ In the grass ecosystem, at base (lowest trophic level) grass is present in plentiful amounts. ▪ The next higher trophic level is primary consumer i.e. herbivore (example – grasshopper). ▪ The number count of grasshoppers is less than that of grass. ▪ The next energy level is primary carnivore (example: rat). The number of rats is less than grasshoppers, because they feed on grasshoppers. ▪ The next higher trophic level is secondary carnivore (example: snakes). They feed on rats. ▪ The next higher trophic level is the top carnivore. (example – Hawk). ▪ As we reach each higher trophic level, the numbers of individual decreases from lower to higher trophic level. ▪ Pyramid of numbers – inverted: tree ecosystem (Detritus food chain) Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 ▪ In this type of pyramid, the number of individuals is increased from lower level to higher trophic level. Example, tree ecosystem. 2. Pyramid of biomass: ▪ Pyramid of biomass represents the total dry weight of organisms. ▪ It is usually determined by collecting all organisms invading each trophic level separately and measuring their dry weight. ▪ This will serve to solve the size difference problem because all kinds of organisms at a trophic level are weighed. ▪ The unit for measurement of biomass is g/m2. ▪ The biomass of a species is expressed in terms of fresh or dry weight. ▪ Measurement of biomass in terms of dry weight is considered more accurate. ▪ Certain mass of living material of each trophic level at a particular time called as standing crop. ▪ The standing crop is measured as the mass of living organisms (biomass) or the number in a unit area. pyramid of biomass: upright ▪ The pyramid of biomass on land contains a large base of primary producers with a lesser trophic level present on top. ▪ The biomass of producer termed as autotrophs is at the maximum trophic level. ▪ The biomass of next trophic level from base, i.e., primary consumers is less than the producers. ▪ The biomass of next higher trophic level, i.e., secondary consumers is less than the primary consumers. ▪ The top, high trophic level consists very less amount of biomass. ▪ On other hand, in many aquatic ecosystems, the pyramid of biomass may be present in an inverted form whereas pyramid of numbers for aquatic ecosystem is upright. ▪ It is because the producers are small phytoplankton that grow and reproduce very rapidly. ▪ Here, the pyramid of biomass has a small base as compared to the consumer biomass at any instant actually exceeding the producer biomass and the pyramid is representing in inverted shape 3. Pyramid of energy: ▪ The pyramid of energy represents the flow of energy from lower trophic level to higher trophic level. ▪ During the flow of energy from one organism to another, there is remarkable loss of energy. ▪ This loss of energy is in the form of heat. ▪ The primary producers like the autotrophs contain more amount of energy available. ▪ The least energy is available in the tertiary consumers. ▪ Thus, shorter food chain has more amount of energy available even at the Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 highest trophic level. ▪ An energy pyramid is regarded most suitable to compare the functional roles of the trophic levels in an ecosystem. ▪ An energy pyramid represents the amount of energy at each trophic level and loss of energy taking place during transfer to another trophic level. ▪ Hence the pyramid is always upward, with a large energy base at the bottom. ▪ Suppose an ecosystem receives 1000 calories of light energy in a given day. ▪ Most of the energy is not absorbed by plants; some amount of energy is reflected back to space. ▪ Green plants utilize only a small portion of that absorbed energy, out of which the plant uses up some for respiration and of the 1000 calories, only 100 calories (10%) are stored as energy rich materials. ▪ Now, suppose an animal eats the plant containing 100 calories of food energy, that animal uses some of it for its own metabolism and stores only 10 calories as food energy. ▪ A lion that eats that animal gets an even smaller amount of energy. ▪ Thus, usable energy decreases while passing from sunlight to producer to herbivore to carnivore. Therefore, the energy pyramid will always be upright. Community Ecology: Community ecology is the study and theory of how populations of organisms interact with each other and react to their non-living surroundings. As a subset of the general study of ecology, this field of specialization explores the organization and functioning of biological communities. Community ecologists protect the environment and save species from extinction by assessing and monitoring environmental conditions such as global warming Community Ecology: Definition One of the earliest formal definitions of community ecology was suggested by Cornell professor Robert Whittaker in 1975. Whittaker characterized community ecology as an assemblage of living organisms that interact and form a community with a unique structure and species composition. Knowing how a community functions is vital to promoting and preserving biodiversity. Community ecology examines how coexisting organisms interact and compete in a particular niche or geographical location such as a woodland, prairie or a lake. Community ecology encompasses all populations of all species that live together in the same area. Community ecologists study ecological interactions and consider such things as how to intervene when a rising deer population is destroying the understory layer of a woodland. Community Ecology Examples Community ecology encompasses many types of ecological interactions that continue to change over time. A forest community includes the plant community, all trees, birds, Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 squirrels, deer, foxes, fungi, fish in a forest stream, insects and all other species living there or migrating seasonally. Similarly, a coral reef community includes a vast number of different species of corals, fish and algae. Abundance and distribution are strong forces that shape the biological community. Community ecology focuses on how interactions between different species affect health, growth, dispersion and abundance of the ecological system. At the community level, species are often interdependent. Several short food chains are common in most biological communities. Food chains often overlap and form food webs of producers and consumers. Community Ecology Theory American, European and British scientists have long held many differing theories on the definition of community ecology, which was first called plant sociology. In the 20th century, opinions differed as to whether ecological niches were self-organized organismic communities or random assemblages of species that thrived because of their particular traits. By the 21st century, theories broadened to include such ideas as the metacommunity theory that focuses on community structures and the evolutionary theory that incorporates principles of evolutionary biology into community ecology. Currently held community ecology theory is based on the supposition that ecological communities are the result of different types of assembly processes. Assembly processes involve adaptation, speciation in evolutionary biology, competition, colonization, altitude, limate, habitat disturbances and ecological drift The theory of community ecology expands upon niche theory, which has to do with an organism having a specific place and role in an ecosystem. Indicators of Ecological Health Species richness refers to the richness, or number, of species found. For example, an annual bird count might yield a species richness of 63 different species of birds spotted in a nature center. One pileated woodpecker is counted the same as 50 chickadees in determining species richness of the area. Species richness does not factor in the total number of individuals found within each species. The number and type of species present in a community gradually increases toward the equator. Species richness decreases towards the polar region. Fewer plant and animal species are adapted to cold biomes. Species diversity looks at overall biodiversity. Species diversity measures species richness as well as the relative number of species present. High species diversity characterizes stable ecological communities. Sudden or significant changes in a community such as an influx of predators can disrupt the predator-prey ecological balance and reduce species diversity. Community Ecology Structure Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 Community ecologists study the interaction between structure and organisms. Structure describes characteristics of ecological niches, species richness and species composition. Species interact with each other and with their environment in many different ways, such as competing for finite resources or working together to trap game. Population dynamics play a pivotal role in communities. The energy pyramid shows how energy is made and transferred by organisms that comprise the food chain. Heterotrophic producers of usable food energy from the sun form the broad base of the pyramid. Primary consumers such as herbivores cannot make food to fuel their cells and must eat producers to live. Secondary consumers are carnivores that eat primary consumers. Tertiary consumers devour secondary consumers, but the apex predator at the top of the pyramid has no natural enemies. A food chain represents the flow of food energy in a community. For instance, phytoplankton are eaten by fish that may be caught and cooked by a human. Only 10 percent of the energy consumed is transferred at each trophic level, which is why the energy pyramid is not inverted. Decomposers play a role by breaking down dead organisms to release nutrients back into the environment. Types of Interspecific Interactions In biology, interspecific interactions refer to the ways in which species interact in their community. The effect of such interactions on different species may be positive, negative or neutral for one or both. Many types of interactions occur in an ecological community and influence population dynamics These are a few examples of those types of interactions: Mutualism: both species benefit from interaction, such as bacteria in the gut that speed digestion (+/+). Commensalism: one species benefits without affecting the other, such as a spider spinning a web on a plant (+/0). Parasitism: one species benefits, but the other is harmed, such as pathogenic microbes (+/-). Predation: one species preys on the other for survival (+/-). Competition: two species fight over limited resources (-/-). Species and Structure Interactions Even small changes in nature can have big effects on community ecology. For instance, structure is influenced by factors such as slight temperature changes, disturbances to habitat, pollution, weather events and species interaction. Relative abundance of food is a stabilizing factor in communities. Normally, there is a check- balance system of food and consumption. Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 Types of Species in Community Ecology Foundation species, like coral in a coral reef community, play a pivotal role in community ecology and shaping structure. Coral reefs are commonly called “rainforests of the sea” because they provide food, shelter, breeding areas and protection for up to 25 percent of all marine life, according to the Smithsonian Museum of Natural History. Threats to coral reefs include climate change, pollution, overfishing and invasive species. Flagship species Flagship species are the species that are on the verge of extinction. They are therefore used as an ambassador to draw society’s attention towards the need to conserve them. The Bengal Tiger, Asian Elephant, African Elephant, and Giant Panda are a few flagship species used by the World Wildlife Fund. Umbrella species Umbrella species are species that are selected as representatives of their ecosystem when conservation plans are being made. By protecting these organisms, other species that are a part of their ecosystem will also benefit under the same conservation "umbrella." An umbrella species is usually chosen to make ecosystem management strategies easier in areas where there are a large number of species of concern or where the true biodiversity of an ecosystem isn’t known. Keystone species like wolves profoundly affect community structure relative to the abundance of the other species. If removed, the loss of key predators dramatically changes the entire community. Predators keep other populations in check that would otherwise overgraze and threaten plant species resulting in a loss of food and habitat. Overpopulation can also lead to starvation and disease. Indicator species indicator species is an organism whose presence, absence or abundance reflects a specific environmental condition. Indicator species can signal a change in the biological condition of a particular ecosystem, and thus may be used as a proxy to diagnose the health of an ecosystem. For example, plants or lichens sensitive to heavy metals or acids in precipitation may be indicators of air pollution. Indicator species can also reflect a unique set of environmental qualities or characteristics found in a specific place, such as a unique microclimate. Invasive species are invaders that are not native to the habitat and disrupt the community. Many types of invasive species like the Zebra Mussel, destroy native species. Invasive species grow rapidly and reduce biodiversity, which weakens the overall animal and plant community within that niche Ecology Succession Ecological succession is a series of changes over time to community structure that affect community dynamics and encourage the assemblance of plants and animals. Primary succession starts with the introduction of organisms and species, usually on newly exposed rock. Pioneer species like lichens on rock come first. Secondary succession happens when orderly recolonization occurs in an area that was previously inhabited before a disruption. For instance, after a wildfire decimates an area, bacteria modify the soil, plants sprout from roots and seeds, bushes and shrubs establish, followed by tree seedlings. Vegetation provides a Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 vertical and horizontal structure that attracts birds and animals to the biological community. What is Ecological Succession? Ecological succession is the steady and gradual change in a species of a given area with respect to the changing environment. It is a predictable change and is an inevitable process of nature as all the biotic components have to keep up with the changes in the environment. The ultimate aim of this process is to reach equilibrium in the ecosystem. The community that achieves this aim is called a climax community. In an attempt to reach this equilibrium, some species increase in number while some other decrease. In an area, the sequence of communities that undergo changes is called sere. Thus, each community that changes is called a seral stage or seral community. All the communities that we observe today around us have undergone succession over a period of time since their existence. Thus, we can say that evolution is a process that has taken place simultaneously along with that of ecological succession. Also, the initiation of life on earth can be considered to be a result of this succession process. If we consider an area where life starts from scratch by the process of succession, it is known as primary succession. However, if life starts at a place after the area has lost all the life forms existing there, the process is called secondary succession. It is obvious that primary succession is a rather slow process as life has to start from nothing whereas secondary succession is faster because it starts at a place which had already supported life before. Moreover, the first species that comes into existence during primary succession is known as pioneer species. 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. 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. Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 Cyclic Succession This is only the change in the structure of an ecosystem on a cyclic basis. Some plants remain dormant for the rest of the year and emerge all at once. This drastically changes the structure of an ecosystem 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 series: Types of Series Explanation Hydrosphere Succession in aquatic habitat. Xerophsere Succession in dry habitat. Lithospherere 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. Examples of Ecological Succession Following are the important examples of ecological succession: Acadia National Park This national park suffered a huge wildfire. Restoration of the forest was left to nature. In the initial years, only small plants grew on the burnt soil. After several years, the forest showed diversity in tree species. However, the trees before the fire were mostly evergreen, while the trees that grew after the fire were deciduous in nature. Ecological Succession of Coral Reefs Small coral polyps colonize the rocks. These polyps grow and divide to form coral colonies. The shape of the coral reefs attracts small fish and crustaceans that are food for the larger fish. Thus, a fully functional coral reef exists. Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course Semester I Course Name (Course Code) Environmental Studies (VAC00006) Academic Session 2024-25 Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) Types of Ecosystems: ❖ FOREST ECOSYSTEMS Forest occupies roughly 40% of the land. In Indian, the forests occupy roughly 1/10th of the total land area. The different components of a forest ecosystem are as follows: 1. Abiotic component These are the inorganic as well as organic substances present in the soil and atmosphere. In addition to the minerals present in forests we find the dead organic debris i.e. the litter accumulation, chiefly in temperate climate. Moreover, the light conditions are different due to complex stratification in the plant communities. Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) 2. Biotic component: The living organisms present in the food chain occur in the following order: Producers These are mainly trees that show much species diversity and greater degree of stratification especially in tropical moist deciduous forests. The trees are of different kind depending upon the kind of the forest formation developing in that climate. Besides trees, there are also present shrubs and a ground vegetation. In these forests, dominant members of the flora, the producers, are such trees as Tectona grandis, Butea frondose, S. rubusta and Logerstroemia parviflora. In temperate: coniferous forests, shrubs and ground flora are insignificant. In temperate deciduous forests the dominant trees are species of Quercus, Acer, Betula, Thuja, Picea etc., where as in a temperate coniferous forest, the producer trees are species of Abies Picea, Pinus Cedrus, Juniper Rhododendron etc. Consumers: These are as follows: i. Primary consumers are the herbivores that include the animals feeding on tree leaves as ants, flies, beetles, leafhoppers, bugs, and spiders etc. and larger animals grazing on shoots and/or fruits of the producers, the elephants, nilgai, deer, shrews, flying foxes, mongoose etc. ii. Secondary consumers are the carnivores like snakes, birds, lizards, fox etc, feeding on the herbivores. iii. Tertiary consumers are the carnivores like lion, tiger etc. that eat carnivores of secondary consumers’ level. Decomposers These are wide variety of microorganisms including fungi (species of Aspergillus, Coprinus, Polyporus, Ganoderma, Fusarium, Alternaria, etc.), bacteria (spp. Of Bacillus, Clostridium, etc.), and actinomycetes, like species of Streptomyces etc. Rate of decomposition in tropical and subtropical forests is more rapid than that in the temperate ones. ❖ GRASSLAND ECOSYSTEM This is a type of terrestrial ecosystem. Grasslands occupy a comparatively fewer area, roughly 19% of the earth’s surface. The various components of a grassland ecosystem are as follows: 1. Abiotic component These are the nutrients present in soil and the aerial environment. Thus, the elements like C, H, O, N, P, S etc. are supplied by carbon dioxide, water, nitrates, phosphates, and sulphates etc., present in air and soil of the area. Moreover, in addition to the above, some trace elements are also present in soilBiotic component These may be categorized as: A. Producers: They are mainly grasses, as species of Dichanthium, Cynodon, Desmodium, Digitaria, Dactyloctenium, Brachiaria, Setaria, Sporobolus, etc. Besides them a few forbes and shrubs also contribute to primary production. B. Consumers: These occur in the following sequences: Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) 1. Primary consumers are the herbivores feeding on grasses are mainly such grazing animals as cows, buffaloes, deers, sheep, rabbit, mouse etc. Besides them there are also present some insects as Leptocorisa, Dysdercus, Oxyrhachis, Cicincella, Coccinella, some termites and millipedes etc, that feed on the leaves of grasses. 2. Secondary consumers are the carnivores feeding on herbivores. These include the animals like fox, jackals, snakes, frogs, lizards, birds etc. Sometimes the hawks feed on the secondary consumers, thus occupying tertiary consumers level in the food chain. C. Decomposers are the microbes active in the decay of dead organic matter of different forms of higher life are fungi, as species of Mucor, Aspergillus, Penicillium, Clodosporium, Rhizopus, etc., and some bacteria and actinomycetes. They bring about the minerals back to the soil, thus making them available to the producers. ❖ DESERT ECOSYSTEM Deserts occupy about 17% of land, occurring in the regions with an annual rainfall of less than 25 cm. The species composition of such ecosystem is much more varied and typical due to extremes of both, temp. and water factors. 1. Abiotic components: Water availability, climate, temperature, sunlight. 2. Biotic components: The various biotic components are as follows: Producer These are shrubs, especially bushes, some grasses and a few trees. The shrubs have widespread, branched root system with their stems and branches variously modified. Sometimes a few succulents like cacti are also present. Some lower plants like lichens and xerophytic mosses may also be present. Consumers The most common animals are reptiles and insects, able to live under xeric conditions. In additions, to them, there are also found some nocturnal rodents and birds. The ship of desert, camels feed on tender shoots of the plants Decomposers These are very few, as due to poor vegetation the amount of dead organic matter is correspondingly less. They are some fungi and bacteria, most of which are thermophilic. ❖ AQUATIC ECOSYSTEM (OCEANS) Major oceans of the world, Atlantic, Pacific, Indian, Arctic, and Antarctic cover approximately 70% of the earth’s surface. 1. Each ocean indeed represents a very large and stable ecosystem. 2. Marine environments, as compared with fresh water, appear to be more stable in their chemical composition due to being saline, and moreover other such physio-chemical as dissolved oxygen content, light and temperature are also different. 1. Abiotic components: Substrate type, water depth, nutrient levels, temperature, salinity, and Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) flow. 2. Biotic components: The biotic components of an ocean ecosystem are of the following orders: Producers Producers are mainly the phytoplankton, such as diatoms, dinoflagellates and some microscopic algae. Besides them, a number of macroscopic seaweeds, as brown and red algae (members of Phaeophyceae and Rhodophyceae), also contribute significantly to primary production. These organisms show a distinct zonation at different depths of water in the sea. Consumers These all are heterotrophic macroconsumers, being dependent for their nutrition on the primary producers. These are as follows: Primary consumers, the herbivores that feed directly on producers, are chiefly crustaceans, mollusks, fish etc. Secondary consumers are carnivores’ fish, as Herring, Shad, Mackerel etc., feeding on the herbivores. Tertiary consumers are other carnivorous fishes like Cod, Haddock, Halibut etc. that feed on other carnivores of the secondary consumers’ level. Thus, these are the top carnivores in the food chain. Decomposers The microbes active in the decay of dead organic matter of producers and macro consumers are chiefly bacteria, fungi, marine worms, echinoderms, crustaceans BIODIVERSITY The term “biodiversity” refers to the variety of living organisms. Biodiversity brings together the different species and forms of life (animal, plant, and other organisms) and their variability, that is to say, their dynamics of evolution in their ecosystems. It is closely related to the function and stability of communities and ecosystems. Definition: Biodiversity can be defining as “the variety (multiplicity) and variability(changeability) among living organisms and the ecological environment in which they exist”. Or, it can be defined as “the sum total of species richness, i.e., the number of species of plants, animals and microorganisms occurring in a given region, country, continent of the entire globe”. Bio= “life” and diversity = “variety”. Hence, biodiversity = “wide variety of life on the earth”. The term biodiversity was coined by Walter G. Rosen in 1986. To describe biodiversity, the following terms are also often used: Biological diversity or, Diversity of life or, Biological variability. Levels of biological diversity: Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) Biological diversity is usually considered at three different levels- a) Genetic diversity: It refers to the variations among the genetic resources of the organisms. Every individual of a particular species differs from each other in their genetic constitution because the gene determines the uniqueness of each individual and each species. Genetic variations represent the differences in the sequence of bases in nucleotides, which constitutes the genetic code. Genetic variations are due to gene mutations, and in an organism with sexual reproduction, these can spread by crossing-over and recombination. Genetic diversity provides the raw materials for adaptation to changing environment and for natural selection to act upon. If a species has more genetic variability, it can adapt better to the changed environment. The UN held Earth Summit on biodiversity in 1992 [Convention on Biodiversity (CBD), Rio de Janerio] and in 2002 (Johannesburg) to create awareness on conservation of biodiversity for the welfare of mankind. b) Species diversity: Species diversity refers to the variety of different types of species found in a particular area. It is biodiversity at the most basic level. It includes all the species ranging from plants to different microorganisms. No two individuals of the same species are exactly similar. An estimated 1.7 million species have been identified till date. c) Ecosystem diversity: The diversity at the ecological/habitat level is known as “eco-system diversity”. For example, the Western Ghats with rich species diversity will have altogether different structure compared to the Thar desert ecosystem, which has far less number of plant and animal species. Likewise, the marine ecosystem although has many types of fishes, yet it differs from the freshwater ecosystem of rivers and lakes in terms of its characteristics. So such variations at ecosystem level are termed as ecosystem diversity. Ecosystem diversity can be measured by three types: Alpha diversity: It refers to diversity within a particular area, community or ecosystem, and is measured by counting the number of species within the ecosystem. Beta diversity: It refers to species diversity between ecosystems and is measured by comparing the number of species that are unique to each of the ecosystems. Gamma diversity: It is a measure of overall diversity for different ecosystems within a region Biogeographical zones of India: India is one of the 12th Mega diverse regions of the world. (Mexico, Columbia, Madagascar, Ecuador, Cameroon, Peru, Brazil, Jairo, China, Malaysia, Indonesia and India). India can be conveniently divided into 10 major regions based on geography, climate and pattern of vegetation seen and the communities of mammals, birds, reptiles, amphibians, insects and other invertebrates that live in them. Each of these regions contains a variety of ecosystems such as forests, grasslands, lakes, rivers, wetlands, mountains and hills which have specific plants and animal species. Each zone individually calls a biogeographical zone. These zones are- Trans-Himalayan Region: Constituting 5.6 percent of the country’s geographical area, this zone includes high altitude cold and arid mountain areas, including cold areas of Ladakh, Jammu & Kashmir, North Sikkim, Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) Lahaul and Spiti areas of Himachal Pradesh. This zone has sparse alpine steppe vegetation that harbors several endemic species like Ibex, Snow leopard, Black necked crane, marbled cat, Marmots. It supports some of the biggest populations of wild sheep and goats in the world. Himalayan Region: It constitutes 6.4 per cent of the total geographical area and includes some of the highest peaks in the world. The Himalayan zone makes India one of the richest areas in terms of habitats and species. The alpine and sub-alpine grassy meadows and moist mixed deciduous forests occupy lowest elevations, they are replaced by chir pine (Pinus roxburgii) and then by banj oak (Quercus leucotrichophora) at around 2000m elevations, provide diverse habitat for endangered species of bovid such as Bharal (Pseudois nayaur), Ibex (Capra ibex), Markhor (Capra falconeri), Himalayan Tahr (Hemitragus jemlabicus), and Takin (Budoreas taxicolor). Other rare and endangered species restricted to this zone include Hangul (Cervus eldi eldi) and Musk Deer (Moschus moschiferus). More than 300 million population of the Indo- Gangetic plain are dependent on the Himalayan waters. 3). The Indian Desert: Indian Desert Zone, biogeographically, it is the eastward extension of the Sahara- Arabian desert system which spread through Iran, Afghanistan and Baluchistan to the Thar area on the Indo- Pakistan border. This arid zone falls west of the Aravalli hill range and comprisesboth the salt and sand deserts of northwestern India constituting 6.6 per cent of the total geographical area, includes the Thar and the Kutch deserts and has large expanses of grassland that supports several endangered species of mammals such as Wolf (Canis lupus), Caracal (Felis caracal), Desert Cat (Felis libyca), Chinkara (Gazella bennettii) and birds of conservation interest viz., Houbara Bustard (Chamydotis undulate) and the Great Indian Bustard (Ardeotis nigriceps).The plant species are Acacia nilotica, Prosopis cineraria, Salvadora oleoides and Tecomella spp. Prosopis juliflora and other species are becoming increasingly widespread. 4). The Semi-Arid Region: This zone covers 16.6 percent of the country. Although overall semi- arid, this zone also has several lakes and marshlands. The grasses and palatable shrub layer of this zone support the highest wildlife biomass. Many plant taxa have African affinity: Acacia, Anogeissues, Balanites, Capparis, Grewia. Anogeissues pendula forest community occurs only in this zone, on gentler slopes of the Aravalli and associated hill ranges. The endangered Asiatic Lion (Panthera leo persica) is also found in this zone, in the Gir forests of Gujarat. The largest herbivores are Blackbuck, Chowsingha, Nilgai, and Gazelle. The cervid species of Sambar (Cervus unicolor) and Chital (Axis axis) are restricted to the better wooded hills and moister valley areas respectively. One part of this zone surrounds desert zone of western Gujrat and Rajasthan (Punjab, Haryana, Delhi, Rajasthan and Gujrat) and the other part consists of the rain- shadow areas behind the Western Ghats (Maharashtra, Andhra Pradesh, Karnataka and Tamil Nadu). 5). Western Ghats: Western Ghats is a mountain range running along the western coast of peninsular India, from Tapti River in the north to Kanyakumari in the south (Figure 1). The moist evergreen forests are most extensive in the Western Ghats. Constituting 4 percent of the country’s geographical area, this zone supports tropical evergreen forests that are home to approximately 15,000 species of higher plants, of which around Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) 4,000 (approx. 27 percent) are endemic. The rainfall is heavy; possibly more than 2,000mm in most areas but can exceed 5,000mm in some areas. Forests have been replaced by tea, coffee, cocoa, rubber, cardamom, chincona and other plantations. There are several endemic faunal species as well, such as the Nilgiri Langur (Presbytis johnii) and the Lion-tailed Macaque (Macaca 9 silenus), Grizzled Giant Squirrel (Ratufa macroura), Malabar Civet (Viverricula megaspila), Nilgiri Tahr (Hemitragus bylocrius). The Malabar grey hornbill is a good indicator of healthy and mature deciduous forest along the Western Ghats. The Travancore Tortoise (Indotestudo forstem) and Cane turtle (Heosemys silvatica) are two endangered taxa restricted to a small area in central Western Ghats. 6). The Deccan Peninsula: This is the largest zone covering as much as 42 percent of the country. The Deccan highlands constitute the principle catchment for a number of South India’s main river systems (Narmada, Tapti, Mahanadi, and Godavari). Sal (Shorea robusta) and Teak (Tectona grandis), the precious timber species. It supports some of the finest forests in India with abundant populations of deer and antelope species such as Chital (Axis axis), Sambar (Cervus unicolor) Barking deer (Muntiacus muntjak) and Gaur (Antilope cervicapra) and Four-horned Antelope (Tetracerus quadricornis). There are small populations of Asian Elephants (Elephas maximus) and Wild Water Buffaloes (Bubalus arnee) as well. Gharhial is restricted to some rivers. 7). The Gangetic plain: This is one of largest zones in India, stretching from Yamuna river eastwards across Uttar Pradesh, Bihar, West Bengal and coastal plains of Orissa. This represents one of the main fertile areas. This flat alluvial zone is topographically fairly homogenous and constitutes 10.8 percent of the country’s geographical area. This zone supports many large and charismatic mammals such as One-horned Rhinoceros (Rhinoceros unicornis), Asian Elephant and Wild Water Buffalo. Other characteristic fauna includes Swamp Deer (Cervus duvauceli), Hog Deer (Axis porcinus) and Hispid Hare (Carprolagus hispidus). Sal (Shorea robusta) forest represents potential vegetation along the Himalaya and mixed dry deciduous forests in plains. Western areas hold relict populations of Rhino, Elephant, Buffalo, Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) Swamp deer, etc. Gharials and Dolphins with several freshwater fishes are found in this area. 8). The North-East Region: This region constitutes 5.2 per cent of the total geographical area. The region represents the transition zone between Indian, Indo-Malayan and indo-Chinese biogeographical regions as well as being a meeting point of the Himalayan Mountains and Peninsular India. This zone is the richest in biological diversity at the community level, at the species level and in endemics. About 50 per cent of the total number of species of India occurs in this zone which also includes a portion of Arunachal Pradesh. In India, apart from the Western Ghats, Northeast India is one of the 25 biodiversity ‘hotspots’ in the world (Myers et. al., 2000). This area has perhaps the most ancient species of living angiosperms and apart from this the rich concentration of primitive flowering plants, several others like orchids, bamboos, ferns, musaceae and cucurbitaceae exhibit maximum diversity here. It is only in north-east that the full richness of the large herbivore fauna typical of alluvial grassland can still be found which include Rhinoceros, Buffalo, Elephant, Swamp deer, Hog deer, Pygmy hog and Hispid hare. 9). Coastal Region: This region constitutes 2.5 per cent of the total geographical area with sandy beaches, mangroves, mud flats, coral reefs and marine angiosperms pastures making them the wealth and health zone of India. The coastline of India stretches from Gujarat to Cape Comorin in the east and includes two major vegetation type mangrove forests and beach forests. The most characteristic tree species of beach forests are Australian pine tree (Casuarina equisetifolia), Cashew tree (Anacardium occidentale) Indian doomba oiltree (Calophyllum inophyllum). A total of 25 islets constitute the Lakshadweep which are of coral origin and have a typical reef lagoon system, rich in biodiversity. The densely populated Lakshadweep islands virtually have no natural vegetation. mangrove forests are found along the deltas, estuaries and backwaters and chiefly comprise the genera of true mangrove Rhizophora, Sonneratia, Heretiera, Xylocarpus. Some animals in this area are Dugong, Humpback Dolphins, Salt water crocodiles, and several variety of turtles are also find here. 10). Island: This region constitutes of 0.3 per cent of the total geographical area. The Andaman and Nicobar groups of island in the Bay of Bengal with 348 islands show an interesting biogeography. These islands are the centers of high endemism and contain some of India’s finest evergreen forests and support a wide diversity of corals. These islands support roughly 2200 species of higher plants. There are about 210 endemic species of which 75 are trees. The dense vegetation of the islands can be broadly classified as littoral and inland types. The littoral forests composed of trees like Andaman bulletwood/Sea Mahua (Manilkara), Indian doomba oiltree (Calophyllum inophyllum), Sea- almond/Indian-almond (Terminalia catappa) fish-poison tree/sea-poison tree (Barringtonia asiastica) and mangroves like red mangrove/Asiatic- mangrove (Rhizophora mucronata), Garjan (R. apiculata), grey or white mangrove (Avicennia marina). The inland vegetation includes the evergreen and deciduous forests with a number of economically important timber species East Indian Mahogany (Pterocarpus dalbergioides), frywood (Albizzia lebbeck) and few others. The Andaman Pig, Nicober Macaue, Nicober tree Shrew, Nicober Megapode, Nacrobium, Hornbill Andaman Wood Pigeon, Nicober Parakeet and also a large proportion of amphibians, reptiles are endemic in this area. Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) Bio-diversity Hotspot: The notion of Biodiversity Hotspot was put forward by Dr. Norman Myers in 1988 to relate “the biologically richest and most endangered eco-regions of the world”. The criteria for designated an area as a hot-spot when- − It contains at least 0.5% or 1500 species of floras endemic species and − Contains 70% of the primary vegetation has to have lost. There are 34 such biodiversity hotspot in global level. Biodiversity Hotspots in India: There are four Hotspots regions in India namely Himalaya, Indo-Burma, Sundalands and Western Ghats and Sri Lanka. Out of them, Himalaya and Western Ghats are mostly located within India’s territory. In the Indo- Burma Biodiversity hotspot, India shares only a small part in north East India. A). The Indo-Burma This Hotspot includes the Asian countries of Combodia, Vietnam, Laos, Thailand, Myanmar and Bhutan, far-off eastern India and extreme southern part of China. Indo-Burma is one of the most defenseless areas due to high rate of resource exploitation and loss of habitat. Out of 13,500 plant species found here over 50% are endemic. Six mammalian Species Large-antlered Muntjac (Muntiacus vuquangenesis), Grey- shanked douc, Annamite striped rabbit, Leaf Deer, are found here. It is the habitat for restricted number of monkeys, langurs, and gibbons. Freshwater Turtles found here are endemic. Practically 1,300 bird species including the endangered white-eared night heron, the leaf muntjac and the Orange necked partridge. B). Western Ghats Western Ghats and Sri Lanka collectively known as Sayadri hills embrace to the mountainous forest in the south-western part of India as well as Srilankan Island. The hotspot which extended nearly 1,82,500 km2 once is currently 12,445 km2 or 6.8% owing to the exceeding high population pressure. The series of hills on the Western part of Indian peninsula and comprises moist deciduous forests and rainforests. This region is typically similar to the Malayan region and also bear faunal similarities with Madagascar. The Purple frog and the Lizard genus Nessia are similar to the Madagascan genus Acontius sp. This is the home for Indian Tigers, Asian Elephants, Civet cat and the endangered Lion Tailed Macaque (Macaca silenus). Almost 77% of amphibians and 62% of reptiles are Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) endemic here. Over 2500 genera representing 6000 vascular plants are found here. More than 3000 plants are endemic. Spices such as Cardamom, and Black pepper are native to this region. The species density is high in the Agasthyamalai Hills, where more than 450 bird species, roughly 140 mammalian species, 260 reptiles, and 175 amphibians are found here. C). Eastern Himalayas T/he region covering Bhutan, northeastern India, and Southern, central, and eastern Nepal. Around 163 threatened species including 45 mammalians, 50 aves, 17 reptilians, 12 amphibians, 3 invertebrates and 36 plant species are found here. One-horned Rhinoceros, Wild Asian Water Buffalo, and the Relict Dragonfly are amongst the animals found here. Himalayan Newt (Tylototriton verrucosus) is the only endemic salamander of India. Himalayan Quail, Cheer Pheasant, Western tragopan are not only endangered but also endemic. Himalayan Vulture and white bellied heron found here are also endangered. 300 species of mammals live here of which 12 are endemic. Important mammals are, Golden Langur, Himalayan Thar, Pygmy Hog, Langur, Asiatic wild dog or Dhol, Sloth Bears, Gaurs, Sambar Deer, Snow Leopard, Black Bear, Blue Sheep, the gangetic Dolphin, Swamp Deer, Namadhapa Flying Squirrel are found here. Several of those species fall in critically endangered category. D). Sundaland The Nicober group of Island is a part of this hotspot. The nicobers are separated from the andamans by about 160 kms. and often experience heavy tidal flow. The region has a volcanoic origin with the coral reef contributing towards rising the island. The landmass to the north is Myanmar while the closest landmass to the south of Sumatra. Nicober tree Shrew, Nicober Pigeon, Nicober palm, several species of Turtles are the important species. India as a ‘Mega diverse’ Nation: ‘Mega diverse’ countries refer to the countries containing 70% of its biodiversity as well as a significant percentage of endemic species. Globally India (60 N to 380 N & 690 to 970 N) stands out as one out of 17 mega diverse countries. The diverse physical features and climatic situations have formed ecological habitats like forests, grasslands, wetlands, coastal and marine ecosystems and desert ecosystems, which harbour and sustain immense biodiversity. Biogeographically, India is situated at the tri-junction of Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) three realms - Afro-tropical, Indo-Malayan and Paleo-Arctic realms, and therefore, has characteristic elements from each of them. This assemblage of three distinct realms makes the country rich and unique in biological diversity. According to Miller Meier, ‘India is remarkable in both species richness and endemism although is ranks 10th position’. Table of Recorded Plant species of India Table of Recorded Animal Species of India India occupies about 2.4% of the Earth’s land area and 11% of plants and 7.43% of the world’s animals. Over 46,000 species of plants have been describe so far, of which 130 species of ancient plants, 1,232 species of pteridohytes, 15,000 species of angiosperms, or flowering plants, 65 species of gymnosperms, 40 species of insectivorous plants, 70 types of saprophytes, 14,500 types of fungi, 2.850 species of mosses, about 990 types of algae, 2,075 species of lichen, 1,082 species of orchids Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) and over 850 species of bacteria and virus are found as reported by the BSI. The ZSI has described over 81,000 species of animals. India is the home for 350 diverse Mammalia (ranked eight highest in the world), 1,200 avian species, 453 types of reptilian species (ranked fifth in the world), and 50,000 recognized species of insects, together with 13,000 butterflies and moths. It is acknowledged to be the native soil of 167 major plant species of mueslis, pulses, millets, fruits, oilseeds, condiments, vegetables, fiber crops and 114 varieties of domestic animals. Out of the 150 botanical sites considered to be important from the stand point of conservation, five places are in India. They are Agastyamalai Hills, Silent Valley, New Amrambalam Reserve, Periyar National Park, and the Eastern and Western Himalayas. On the other hand, endemism in the Indian Reptiles and Amphibians are high. Approximately 187 reptiles and 110 amphibian species are endemic and occur in India. Threats to biodiversity: The most obvious manifestation of biodiversity loss is the extinction of species. This is a natural phenomenon: species have been going extinct since life began. Indeed, it is estimated that many more species have gone extinct than exist at present. From the conservative estimate that the Earth is home to 10 million species in all, it is estimated that between 0.2 and 0.6 percent of species are being lost every year. This rate is at least 10,000 times greater than the ‘background’ or natural rate of species extinction, as estimated using the fossil record. As per CBD, 2010, there are five major threats to Biodiversity-Habitat Change, Over Exploitation, Invasive Species, Pollution and Climate Change. The main causes of biodiversity loss are considered under the following headings: Habitat Loss and Habitat Fragmentation: Habitat means the place or type of site where an organism or population naturally occurs. When a natural habitat, such as a forest or wetland, is altered so dramatically that it no longer supports the species it originally sustained. Plant and animal populations are destroyed or displaced, leading to a loss of biodiversity. It is called habitat loss or habitat destruction. Habitat destruction is different from habitat degradation. According to IUCN, a decline in species- specific habitat quality that leads to reduced survival and/or reproductive success in a population is called habitat degradation. Habitat fragmentation is the ‘breaking apart’ of continuous habitat into distinct pieces. Loss of habitat, habitat degradation, and habitat fragmentation represents significant causes of known extinction and leads to reduce genetic viability and ultimately cause for genetic erosion. The loss of habitats is the primary reason for the loss of biodiversity. When people cut down trees, fill a wetland, plough grassland or burn a forest, the natural habitat of a species is changed or destroyed. These changes can kill or force out many plants, animals and microorganisms as well as disrupt complex interactions among the species. Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) Introduction of invasive species An invasive species (also called introduced, exotic, non-native) can be any kind of living organism that is not native to an ecosystem and which has a tendency to damage the ecosystem. Common characteristics of invasive species include rapid reproduction and growth, high dispersal ability, phenotypic plasticity (ability to adapt physiologically to new conditions) and ability to survive on various food types and in a wide range of environmental conditions and have potential to cause extinction to native species and ecosystem. Invasive species are capable of causing extinctions of native plants and animals by competing with them for limited resources and altering habitats. Thus, leading to loss of biodiversity. The sudden introduction of invasive species to a given ecosystem (especially on islands and in freshwater habitats) causes disastrous consequences for native species. Such introductions are usually the result of human activities. The accidental introduction of an Atlantic comb jellyfish species to the Black Sea is a well-known example. These invaders have out-competed native fauna, and now comprise some 95 percent of the Black Sea’s total biomass. In the US, meanwhile, the introduction of exotic species has been implicated in close to 70 percent of the past century’s freshwater fish extinctions. Overexploitation The term overexploitation refers to the human activities connected with excessive capturing and harvesting (hunting, fishing, farming) of organisms. According to IUCN, it is an exploitation of (removal of individuals or biomass from) a natural population at a rate greater than the population is able to match with its own recruitment, thus tending to drive the population towards extinction. Overexploitation of a particular species reduces the size of its population to an extent that it becomes vulnerable to extinction. The decline of the Earth’s largest terrestrial animal, the African elephant, is a classic example of the impact of overhunting. Largely because of the trade in ivory, elephant populations have been declining in most of Africa. Pollution Pollution from toxic chemicals undoubtly proves to be a threat for the survival species and sustenance of ecosystem. Pollution alters the physiochemical properties and degrades the quality of land, water and air. Species with a small range of tolerance is often threatened to extinction. Climate Change The distribution of species is largely governed by climatic and seasonal changes. Distribution of vegetation is depending on climate, which in turn governs the distribution of animals. Changes in temperature, solar radiation, wildfire, rainfall, flood, drought, storms, snowfall, melting glaciers, and variable stream flow: all are the limiting conditions to the distribution of plants and animals. Species populations may be lost if they are not capable of adapting to new conditions or relocating Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) to new habitats. In the past 30 years the coral reefs in Caribbean region have shrunken by 80%. Earning from diving based tourism was nearly 20% of the total tourism earnings earlier but have presently declined so as to incur a loss. Fishery sector has also been severely affected(UNEP,2008) Hunting and Poaching Both legal and illegal hunting is a major threat. Wildlife is continuously being hunted and poached for food, fashion, profit and make beliefs. The multibillion dollar illegal trade in protected species operates as one of the most profitable illicit markets in the world today. Indian Pangolin (Manis Crassicaudata) or Thick Tailed Pangolin is the most hunted animal in India and world's most trafficked wild mammal. The highly endangered Indian Pangolin is about to become extinct, almost a 100,000 Pangolins are captured every year in India for illegal trade Over 11,000 tortoises and freshwater turtles have entered illegal wildlife trade in India every year since 2009. According to TRAFFIC, more than 1 lakh freshwater turtles and tortoises were poached illegally between 2009 to 2019. Major wildlife crime in India includes poaching of tigers, rhinos and the sale of Star tortoises. Tigers are an endangered species, poached for their skin and bones to cater to an illegal market. Their body parts are used in Asian medicines and tiger claws are used in jewelry. Tiger whiskers are considered a dreadful poison in Malaysia and a powerful aphrodisiac in Indonesia. Apart from tigers, India is also witnessing a rise in wildlife crime against Rhinoceros. Driven by a soaring demand for their horn, hundreds of rhinos are being killed, illegally. According to a report by TRAFFIC and the International Union for the Conservation of Nature (IUCN), sophisticated poachers are using veterinary drugs, poison, cross bows and high caliber weapons to kill rhinos. The Indian rhino could once be found from Pakistan, all the way through India, Nepal, Bangladesh, Bhutan and Myanmar. However, the current population of this species is dwindling and today only about 2500 survive in India and Nepal. Human-Wildlife conflict Human-wildlife conflict is defined by the World Wide Fund for Nature (WWF) as “any interaction between humans and wildlife that results in negative impacts of human social, economic or cultural life, on the conservation of wildlife populations, or on the environment.” The main causes of human wildlife conflict were human settlement, agricultural expansion, illegal Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) grass collection, over grazing by livestock and deforestation in national park. Some examples of Human-Wildlife conflicts in India Areas of Major Species Types of Conflict Conflict Tiger (Panthera Cattle lifting, Injuries or death to humans/ man- A. All India tigris) eating B. Sundarbans Lion (Panthera leo) Habitual livestock depredation, Injuries or death to Gir Forest, Gujarat humans Elephant (Elephas Crop raiding, Injuries or death to humans A. All wild elephant maximus) bearing areas Reptiles Injuries or death to humans, Man eating (Salt water A. All India or Estuarine Crocodiles) B. Sunderbans Asiatic Black Bear Livestock depredation (Brown Bears), Injuries or A. Ladakh (Ursus thibetanus) death to humans (Sloth Bears) B. Central India Birds / Bats Crop raiding, Bird hits to aircraft All India Solutions to reduce Human-Wildlife conflicts: 1. Awareness programs in affected regions to encourage the following: Moving about in groups, preferably with an adult present. Avoiding or reducing movements away from human settlements at certain times of the day. Making noises (such as coughing) when approaching areas of dense vegetation. Avoiding hunting or consuming the prey species of big mammal species. 2. “Encounter Training” programs to teach people how to react in encounters with leopards (e.g., pointers on eye contact, posture, etc.) 3. Reforestation activities in the Garhwal hills to enhance the natural prey base. To be effective, this must be done in conjunction with finding alternative sources of energy. 4. Alternative sources of energy, thus reducing biotic pressure on surrounding forests, and, indirectly, reducing the number of human-leopard encounters. 5. Compensation for injuries/losses to both humans and livestock. Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) 6. Relocation of agricultural activities out of wildlife areas. 7. Consolidation of human settlement patterns that are near wildlife areas. 8. Creation of secure key areas of habitat, such as routes or corridors, that will permit wildlife to move freely; e.g. Gokwe North, Zimbabwe 9. Securing separate water points for wildlife. The distribution of wildlife populations can be manipulated by changing the location of water points and providing salt licks at strategic sites. 10. Repositioning the boundaries of protected areas. 11. Changing cropping regimes, e.g. growing crops not palatable to elephants; diversify into other types of crops; using intercropping layouts for crops; changing timing of harvests. 12. Education programs that teach people about the leopard, its habits and its needs. Human-wildlife coexistence It is as complex and context-specific as conflict. At the most basic level, the goal of coexistence requires that at some level and in some form, humans must choose to share landscapes and natural resources with wildlife in sustainable ways. If human-wildlife conflict is about conflicts between stakeholders over wildlife, then achieving coexistence ideally requires agreement or at least cooperation between stakeholders over how to manage a situation. The concept of coexistence is emerging into mainstream conservation science with a rich diversity of developing ideas and may best be mobilized as a flexible concept to ensure that diverse research disciplines collaborate on the maturation of this concept. Conservation of biodiversity: “Biodiversity conservation refers to the protection, upliftment, and management of biodiversity in order to derive sustainable benefits for present and future generations.” Objectives: Conservation of biological diversity leads to conservation of essential ecological diversity to preserve the continuity of food chains. The genetic diversity of plants and animals is preserved. It ensures the sustainable utilization of life support systems on earth. It provides a vast knowledge of potential use to the scientific community. A reservoir of wild animals and plants is preserved, thus enabling them to be introduced, if need be, in the surrounding areas Biological diversity provides immediate benefits to the society such as recreation and tourism. Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) Biodiversity conservation serves as an insurance policy for the future. How do we conserve Biodiversity? There are two basic strategies of biodiversity conservation, in situ and ex situ (off site). In-situ Conservation Ex-situ Conservation In Situ Conservation In Situ Conservation refers to the preservation and protection of the species in their natural habitat. It means the conservation of genetic resources in natural populations of plant or animal species. In situ conservation involves the management of biodiversity in the same area where it is found. In situ, biodiversity conservation has many advantages It preserves species as well as their natural habitat. It ensures protection to a large number of populations. It is economic and a convenient method of conservation It doesn’t require species to adjust to a new habitat. Different methods of In-situ conservation include biosphere reserves, national parks, wildlife sanctuaries, biodiversity hotspots, gene sanctuary, and sacred groves. It is defined as the conservation of species within their natural habitat, where the natural ecosystem is protected and maintained. In-situ conservation possesses numerous advantages. Some of the important advantages of in-situ conservation are as follows: It is a cost-effective and convenient way of biodiversity conservation. Various living organisms can be conserved at the same time. They can evolve better and can easily get adapted to various environmental conditions. In-situ conservation occurs in places like national parks, wildlife sanctuaries, and biosphere reserves Biosphere Reserves According to UNESCO the Biosphere Reserve define as the “learning places for sustainable development” The biosphere reserve are unique entities for both public and the natural world and are living examples of coexistences between mankind and nature although respecting each other’s needs. Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) It serves as the undisturbed natural areas for scientific research and study. Criteria to be a Biosphere reserve: A site that must contain an effectively protected and minimally disturbed core area of value of nature conservation. The core area should be typical of a bio-geographical unit and large enough to sustain viable populations representing all trophic levels in the ecosystem. The management authority to ensure the involvement/cooperation of local communities to bring variety of knowledge and experiences to link biodiversity conservation and socio- economic development while managing and containing the conflicts. Areas potential for preservation of traditional tribal or rural modes of living for harmonious use of environment. Zones of Biosphere Reserve There are three types of biosphere reserve zonation: Core Zone Buffer Zone Transition Zone Core Zone This is a legally protected area where human intervention is strictly prohibited. It is the innermost undisturbed ecosystem. The information from these areas helps to assess the sustainability of activities, or maintenance of environmental quality in the surrounding areas. Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) Buffer Zone The area surrounding the core zone is the buffer zone. Here only the research and education activities are permitted to humans. These activities should not obstruct the conservation objectives of the core area. This area also includes activities that help to manage natural vegetation, agricultural land, fisheries, or forests to enhance the quality of production. This zone might also include recreation and tourism facilities. Human activities are less intensive in this zone as compared to the transition zone. Transitional Zone It is the outermost area of a biosphere reserve where human activities like cropping, recreation, forestry, and settlements are permitted with the cooperation of reserve management and local people. Through these activities, the degraded area is resumed to its natural form. The local communities, scientists, conservation agencies, cultural groups, and other stakeholders work in this zone to use the area in a sustainable way for the welfare of humans living there. Example- Sundarban, Nanda Devi, Nilgiri Biosphere researve, and Manas in India. National Parks These are limited reserves maintained by the government for the conservation of wildlife as well as the environment. Human activities are prohibited in national parks and they are solely dedicated to the protection of natural fauna of the area. They mostly occupy an area of 100-500 square km. There are a total of 104 national parks in India, right now. The national parks may even be within a biosphere reserve. These are small reserves that are protected and maintained by the government. Its boundaries are well protected, where human activities such as grazing, forestry, habitat, and cultivation are restricted A Sanctuary can be upgraded to a national park. The area is protected by statutory law. Example- Kanha National Park (M.P.), Gir National Park(Gujarat), Kaziranga National Park(Assam), and so on. Importance of Biosphere Reserves The importance of biosphere reserves is mentioned below: Conservation Biosphere reserves conserve the species, ecosystems, genetic diversities, and landscapes without affecting the inhabitants. Development Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) It ensures sustainable developments including economic, cultural, social and economic developments. Restoration The biosphere reserves restore any damage caused to the ecosystems and habitats. Education and Research These areas provide a lot of information on how to restore, conserve, and develop the ecosystem. The researches provide ways to recreate landscapes that have been affected by human activities. Land Use Planning All the landowners, public institutions, farmers, scientists, industry, and conservation groups found in these areas can work together to look for comprehensive land management. Healthy Ecosystems They help in maintaining healthy ecosystems by preventing soil erosion, protecting water springs, and maintaining the decomposers to maintain the soil quality Wildlife Sanctuaries Wildlife Sanctuaries are protected areas meant only for the conservation of wild animals. Killing, Poaching and Hunting is prohibited but local people can gather forest resources. A few human activities such as cultivation, wood collection, and other forest product collection are allowed here, but they must not interfere with the conservation of the animals. Tourist visits are also allowed in these areas. There are a total of 551 wildlife sanctuaries in India. These are the places where only wild animals can be found. Certain human activities like timber harvesting, cultivation, collection of woods, and other forest products are permitted unless they interfere with the conservation project. The ownership of a sanctuary could rest in the control either of a government or in any private organization or person. Example- Pulicat (A.P.) Abohar Wildlife Sanctuary, Mudumalai Wildlife Sanctuary, etc. Biodiversity Hotspots A biodiversity hotspot are the areas of conservation where there is strictly a minimum of 1500 species of vascular plants and a habitat that has lost its 70% cover. These are protected areas for various purposes where the wildlife, inhabitant lifestyle, and domesticated plants and animals are conserved. Tourist and research activities are allowed. Example- The Himalayas, The Western Ghats, The North East, and The Nicobar Islands. Gene Sanctuary Gene sanctuary is a conservation area reserved only for plants. India has its only gene sanctuary set up in Garo Hills of Meghalaya for the conservation of wild species of Citrus. Plans to open more such Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) sanctuaries are underway. Sacred Groves Sacred Groves are conserved areas for wildlife protected by communities due to religious beliefs. It is mostly a part of the forest where its wildlife is given complete protection. Ex-Situ Conservation: As per CBD, ex-situ conservation may be referred to as “the conservation of components of biological diversity outside their natural habitats”. It consists of entire flora or faunal collection, such as- Botanical Gardens Zoological Gardens and parks Wildlife research facilities Seed (germplasm banks) Pollen/Semen/Ovum bank Gene and gene plasm assemblage of wild and domesticated taxa Zoological Gardens and Central Zoo Authority (CZA): “Zoo means a stationary or mobile establishments, where confined animals are kept for exhibition to the public and extend to rescue centers but does not embrace an organization of a licensed dealer in captive animals” Over the years zoos have got transformed into centers for wildlife conservation and education. If properly manage, it serves a useful role in the preservation of wild animals. Example: Alipore Zoological Gardens, Nandankanan Zoo etc. Botanical gardens: Botanic gardens are institutions holding documented collections of living plants for the purpose of scientific research, conservation, display and education. In 2018, BGCI updated the criteria that define a botanic garden to have a greater emphasis on conserving rare and threatened plants, compliance with international policies and sustainability and ethical initiatives. Example: Acharya Jagadish Chandra Bose Indian Botanic Garden, Howrah, Botanical Garden of Forest Research Institute, Dehradun, National Botanic Gardens, Lucknow Several techniques also followed in ex-situ conservation- Captive breeding: It is the process of breeding animals outside the natural habitats of those organisms in restricted human controlled conditions. Example: Breeding programme for the Bengal tigers of India was initialized in 1880 at Alipore Zoological Gardens of Calcutta. Breeding programme for the Asiatic Lion form Gir forest to Kuno wildlife Sanctuary, M.P. and also to emphasized the planned Lion Safari in Uttar Pradesh. Department Chemistry Brainware University, Kolkata Programme Name and Semester: Undergraduate course (Semester I) Course Name (Course Code): Environmental Studies (VAC00006) Cryopreservation: Cryopreservation or cryoconservation is a technique where cells or whole tissue that are vulnerable to damage caused by chemical reactivity or time are preserved by cooling to sub- zero temperatures, preferably at -196⁰C in liquid nitrogen. Gene Banks: A collection of seeds, plants, or animals, maintained as a repository of genetic material, typically to preserve genetic diversity. It is important because- Safeguard the biodiversity. Present resources for reproduction. Offer food solution in the period of calamity. Food security for coming generation Examples: The Svalbard Global Seed Vault on the Norwegian island of Spitsbergen is most famous for the seed bank facilities. In India ICAR,GoI also established a number of gene banks for embryos, vegetables seeds and gametes at, National Bureau of Plant Genetic Resources (NBPGR), National Bureau of Animal Genetic Resources (NBAGR), National Bureau of Fish Genetic Resources(NBGFR) etc. Red Data Book: Red data book is the document established by IUCN for documenting the rare and endangered species of plants, animals, fungi and also a few local species that exist within a state or country. Extinctions are a normal part of evolution: they occur naturally and periodically over time. There’s a natural background rate to the timing and frequency of extinctions: 10% of species are lost every million years; 30% every 10 million years; and 65% every 100 million years. Mass Extinction: Mass extinctions are defined as periods with much higher extinction rates than normal. They are defined by both magnitude and rate. Magnitude is the percentage of species that are lost. Rate is how quickly this happens. These metrics are inevitably linked, but we need both to qualify as a mass extinction. International Union for Conservation of Nature (IUCN) is an international organization (NGO) working in the field of nature conservation and sustainable use of natural resources. It is involved in data gathering and analysis, research, field projects, advocacy, lobbying and education. The organization is best known for compiling and publishing the IUCN Red List, which assesses the conservation status of species worldwide.

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