Biodiversity And Its Conservation

Class 12 | Biology — Zoology | Chapter 11

Class 12 Unit 11 Biology

Biodiversity and its Conservation

Nilgiris Thar is an endangered species in the IUCN red list of threatened species due to hunting and poaching.

Chapter Outline

• 11.1 Biodiversity
• 11.2 Importance of biodiversity – Global and India
• 11.3 Biogeographical regions of India
• 11.4 Threats to biodiversity
• 11.5 Causes of Biodiversity Loss
• 11.6 IUCN
• 11.7 Biodiversity and its conservation

Learning Objectives

• Acquire knowledge about concept, level and patterns of biodiversity.
• Appreciate the magnitude of India's biodiversity.
• Understand biogeographical regions and resources of India.
• Gain insight into the threats to biodiversity.
• Understand the reasons/causes and effects of extinction.

A wide variety of living organisms including plants, animals and micro-organisms with whom we share this planet earth makes the world a beautiful place to live in. Living organisms exist almost everywhere from mountain peaks to the ocean depths; from deserts to the rainforests. They vary in their habit and behaviour, shape, size and colour. The remarkable diversity of living organisms forms an inseparable and significant part of our planet, however, the ever increasing human population is posing serious threats to bio-diversity. In this chapter, we shall discuss biodiversity – concepts, levels, magnitude and patterns, importance of biodiversity, biogeographical regions of India, threats to biodiversity, causes of biodiversity loss, extinction, and biodiversity conservation.

11.1 Biodiversity

The 1992 UN Earth Summit defined Biodiversity as the variability among living organisms from all sources, including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part. This includes diversity within species, between species and ecosystems of a region. It reflects the number of different organisms and their relative frequencies in an ecological system and constitutes the most important functional component of a natural ecosystem. It helps to maintain ecological processes, create soil, recycle nutrients, influence climate, degrade waste and control diseases. It provides an index of health of an ecosystem. The survival of human race depends on the existence and wellbeing of all life forms (plants and animals) in the biosphere.

11.1.1 Concept of Biodiversity

The term biodiversity was introduced by Walter Rosen (1986). Biodiversity is the assemblage of different life forms. Each species is adapted to live in its specific environments. The changes in climatic conditions are reflected in the distribution and pattern of biodiversity on our planet. The number of species per unit area declines as we move from tropics towards the poles. The Tundra and Taiga of northern Canada, Alaska, northern Europe and Russia possess less than 12 species of trees. The temperate forests of the United states have 20-35 species of trees, while the tropical forests of Panama have over 110 species of trees in a relatively small area.

11.1.2 Levels of Biodiversity

Edward Wilson popularized the term 'Biodiversity' to describe diversity at all levels of biological organization from populations to biomes. There are three levels of biodiversity – Genetic diversity, Species diversity and Community or Ecosystem diversity (Figure 11.1).

Genetic Diversity

Genetic diversity refers to the differences in genetic make-up (number and types of genes) between distinct species and to the genetic variation within a single species; also covers genetic variation between distinct populations of the same species. Genetic diversity can be measured using a variety of molecular techniques. India has more than 50,000 genetic variants of Paddy and 1000 variants of Mango. Variation of genes of a species increases with diversity in size and habitat. It results in the formation of different races, varieties and subspecies. Rouwolfia vomitaria, a medicinal plant growing in different ranges of the Himalayas shows differences in the potency and concentration of the active ingredient reserpine due to genetic diversity. Genetic diversity helps in developing adaptations to changing environmental conditions.

Species Diversity

Species diversity refers to the variety in number and richness of the species in any habitat. The number of species per unit area at a specific time is called species richness, which denotes the measure of species diversity. The Western Ghats have greater amphibian species diversity than the Eastern Ghats. The more the number of species in an area the more is the species richness (Figure 11.1a).

The three indices of diversity are - Alpha, Beta and Gamma diversity.

1. Alpha diversity: It is measured by counting the number of taxa (usually species) within a particular area, community or ecosystem.
2. Beta diversity: It is species diversity between two adjacent ecosystems and is obtained by comparing the number of species unique to each of the ecosystem.
3. Gamma diversity: It refers to the diversity of the habitats over the total landscape or geographical area.

Community or Ecosystem Diversity

Community or Ecosystem diversity is the variety of habitats, biotic communities, and ecological processes in the biosphere. It is the diversity at ecosystem level due to diversity of niches, trophic levels and ecological processes like nutrient cycles, food webs, energy flow and several biotic interactions. India with its alpine meadows, rain forests, mangroves, coral reefs, grass lands and deserts has one of the greatest ecosystem diversity on earth.

11.1.3 Magnitude of Biodiversity

Biodiversity is often quantified as the number of species in a region at a given time. The current estimate of different species on earth is around 8 - 9 million. However, we really don't know the exact magnitude of our natural wealth. This is called the 'The Taxonomic impediment'. So far about 1.5 million species of microorganisms, animals and plants have been described. Each year about 10 to 15 thousand new species are identified and published worldwide, of which 75 percentage are invertebrates. The number of undescribed species is undoubtedly much higher.

India is very rich in terms of biological diversity due to its unique bio-geographical location, diversified climatic conditions and enormous eco-diversity and geo-diversity. According to world biogeographic classification, India represents two of the major realms (The Palearctic and Indo-Malayan) and three biomes (Tropical humid forests, Tropical Dry (or) Deciduous forests and Warm Deserts (or) Semi deserts). With only about 2.4 percentage of the world's total land surface, India is known to have over 8 percentage of the species of animals that the world holds and this percentage accounts for about 92,000 known species.

India is the seventh largest country in the world in terms of area. India has a variety of ecosystems, biomes with its varied habitats like, hills, valleys, plateaus, sea shores, mangroves, estuaries, glaciers, grasslands and river basins. It also reflects different kinds of climates, precipitation, temperature distribution, river flow and soil. India is one of the 17 mega biodiversity countries of the world and has ten biogeographic zones with characteristic habitat and biota.

Quote

"The world is currently undergoing a very rapid loss of biodiversity comparable with the great mass extinction events that have previously occurred only five or six times in the earth's history." - World Wildlife Fund

11.1.4 Patterns of Biodiversity Distribution

The distribution of plants and animals is not uniform around the world. Organisms require different sets of conditions for their optimum metabolism and growth. Within this optimal range (habitat) a large number and type of organisms are likely to occur, grow and multiply. The habitat conditions are determined by their latitudes and altitudes.

Latitudinal and Altitudinal Gradients

Temperature, precipitation, distance from the equator (latitudinal gradient), altitude from sea level (altitudinal gradient) are some of the factors that determine biodiversity distribution patterns. The most important pattern of biodiversity is latitudinal gradient in diversity. This means that there is an increasing diversity from the poles to equator. Diversity increases as one moves towards the temperate zones and reaches the maximum at the tropics. Thus, tropics harbour more biodiversity than temperate or polar regions, especially between the latitudes of 23.5° North and 23.5° South (Tropic of Cancer to the Tropic of Capricorn).

Harsh conditions exist in temperate areas during the cold seasons while very harsh conditions prevail for most of the year in polar regions. Columbia located near the equator (0°) has nearly 1400 species of birds while New York at 41° North has 105 species and Greenland at 71° North has 56 species. India, with much of its land area in the tropical latitudes, is home for more than 1200 species of birds. Thus it is evident that the latitude increases the species diversity. Decrease in species diversity occurs as one ascends a high mountain due to drop in temperature (temperature decreases at 6.5°C per Kilometer above mean sea level).

Reasons for the Richness of Biodiversity in the Tropics

• Warm tropical regions between the tropic of Cancer and Capricorn on either side of equator possess congenial habitats for living organisms.
• Environmental conditions of the tropics are favourable not only for speciation but also for supporting both variety and number of organisms.
• The temperatures vary between 25°C to 35°C, a range in which most metabolic activities of living organisms occur with ease and efficiency.
• The average rainfall is often more than 200 mm per year.
• Climate, seasons, temperature, humidity, photoperiods are more or less stable and encourage both variety and numbers.
• Rich resource and nutrient availability.

Mean Sea Level (MSL)

Mean Sea Level (MSL) is an average level of the surface of one or more of Earth's oceans (or seas) from which heights such as elevations may be measured. As we travel by train we notice names of stations on big yellow signboards on which is usually written how much elevated that place is compared to MSL. For example, Erode junction is about 171 meters above MSL.

Species-Area Relationships

German Naturalist and Geographer Alexander von Humboldt explored the wilderness of south American jungles and found that within a region the species richness increased with increasing area but upto a certain limit. The relationship between species richness and area for a wide variety of taxa (angiosperm plants, birds, bats, freshwater fishes) turned out to be the rectangular hyperbola. On a logarithmic scale, the relationship is a straight line described by the equation:

log S = log C + Z log A

where:

• S = Species richness
• A = Area
• Z = Slope of the line (regression coefficient)
• C = Y-intercept

Regression coefficient Z generally has a value of 0.1 to 0.2 regardless of taxonomic group or region. However, in case of the species-area relationship in very large areas like entire continents, the slope of the line appears to be much steeper (Z-value in the range of 0.6 to 1.2). For example, in case of the fruit eating (frugivorous) birds and mammals in the tropical forests of different continents, the slope is found to be a steeper line of 1.15 (Figure 11.2).

11.2 Importance of Biodiversity – Global and India

Biodiversity is the variety of life on earth. That is, it is the number of different species of flora and fauna including microorganisms. These organisms can inhabit different ecosystems with varying conditions like the Rainforests, Coral reefs, Grasslands, Deserts, Tundra and the Polar ice caps. This variety (Biodiversity) is essential for the wellbeing of our planet and sustenance of life as a whole.

Rivet Popper Hypothesis

Ecologist Paul Ehrlich proposed the 'Rivet Popper Hypothesis' for better understanding the loss of each species in the ecosystem. He compared each species of an ecosystem with rivets in the body of an aeroplane. Thousands of rivets (species) join all the parts of an aeroplane (ecosystem). If every passenger travelling in the aeroplane starts taking rivets home (loss of species), initially it may not affect flight safety (proper functioning of the ecosystem). However, the plane becomes dangerously weak over a period of time, when more and more rivets are removed. Moreover, which rivet is removed is also important. When the key rivets (removal of key stone species) on the wings of the aeroplane are removed, undoubtedly it poses a serious threat to the flight safety. Thus we understand the role of every species for the harmonial function of an ecosystem.

Importance of Biodiversity

The importance of biodiversity can be viewed and measured as:

• a) Ecosystem services
• b) Biological resources
• c) Social benefits of biodiversity

The organization and functioning of ecosystems world over is effected and dependent on biodiversity and its richness. The major functional attributes are:

• Continuity of nutrient cycles or biogeochemical cycles (N₂, C, H₂O, P, S cycles)
• Soil formation, conditioning or maintenance of soil health (fertility) by soil microbial diversity along with the different trophic members increases ecosystem productivity and provides food resources
• Act as water traps, filters, water flow regulators and water purifiers (forest cover and vegetation)
• Climate stability (forests are essential for rainfall, temperature regulation, CO₂ absorption, which in turn regulate the density and type of vegetation)
• Forest resource management and sustainable development
• Maintaining balance between biotic components
• Cleaning up of pollutants – microbes are the biggest degraders of molecules including many anthropogenic ones which are present in effluents, sewage, garbage and agro-chemicals
• Ecological stability – the varieties and richness of species contribute to ecological stability and survival of species

Biodiverse regions are reservoirs of biological resources like food resources, gene pool, genetic resource, medicinal resources, bio-prospecting to provide unique aesthetic value and hot spots for Ecotourism. Along with forest resources and wildlife it has commercial significance, and acts as an indicator of the health of the ecosystem. Endemism is a crucial indicator of richness.

11.3 Biogeographical Regions of India

As per the international 'biome' type of classification based upon climate, fauna and flora and the soil conditions, India can be divided into ten different biogeographic zones (Figure 11.3 and Table 11.1).

Table 11.1 Biogeographical Zones of India

S.No.	Biogeographical Zone	Biotic Provinces	Area %	Biota
1	Trans Himalaya	Comprises mountain areas of Ladakh (J&K), North Sikkim and Lahaul and Spiti of H.P	5.6%	Alpine steppe vegetation, richest wild sheep and goat community in the world (renowned for its quality wool), Chiru, black rocked crane, etc.
2	Himalayas	The entire mountain chain running from western to north eastern India	6.4%	Alpine forest, orchids, rhododendrons, wild sheep, mountain goats, shrew, snow leopard, panda etc.
3	Indian Desert	The extremely arid area west of the Aravalli hill range comprising of the sand desert of Rajasthan (Thar) and the salt desert of Gujarat (Kutch)	6.6%	Thorn forests, deciduous forest, wild ass (endemic), Indian bustard, camel, foxes, snakes etc.
4	Semi-arid zones	The zones in between the desert and the Deccan plateau including the Aravalli hill range	16.6%	Thorn and deciduous forest, mangroves, Nilghai, black buck, four horned antelopes, sambar, chital, spotted deer, Asiatic lion, tiger, leopard, jackal etc.
5	Western Ghats	Mountain ranges from Sat Pena in South Gujarat to the southern most tip of Kerala	4%	Evergreen to dry deciduous forests, Nilgiri langur, Indian elephant, Nilgiri tahr (state animal of Tamil Nadu), the grizzled squirrel and lion tailed macaque (endemic)
6	Deccan Peninsula	A large area comprising of raised land bound by the Sathpura range on the north, Western Ghats on the west and Eastern Ghats on the east	42%	Deciduous forest, thorn forests and pockets of semi ever green forests, chital, sambar, sloth bear, barking deer, Nilghai, elephant, black buck etc.
7	Gangetic Plains	One of most fertile region of India which extends from eastern Rajasthan through Uttar Pradesh, Bihar and West Bengal	10.8%	Mangrove forest, dry deciduous forest, rhinoceros, elephant, buffalo, tiger, crocodile, swamp deer, hog deer etc.
8	North-East India	The plains and non Himalayan hill ranges of north eastern India. This region represents the transition zone between the Indian, Indo-Malayan and Indo-Chinese bio geographical regions. It is the meeting point of the Himalayan mountains and peninsular India	5.2%	Biogeographical Gateway for much of India's fauna and flora and also biodiversity hot spot. Semi ever green forest, monsoon forests, swamps and grassland, Indian rhinoceros, golden langur, leopard etc.
9	Coastal Region	The coastline from Gujarat to Sunderbans with sandy beaches, mud flats, coral reefs, and mangroves	2.5%	Mangroves, sponges, corals, crabs, turtles, tunas, ornamental fishes etc.
10	Andaman and Nicobar Islands	Andaman and Nicobar Islands in the Bay of Bengal	0.3%	Evergreen forest, a wide diversity of corals, Narcondam hornbills, giant robber crab, turtle, wild boar, water monitor, south Andaman krait etc.

11.4 Threats to Biodiversity

Even though India is one of the 17 identified mega diverse countries of the world, it faces lots of threats to its biodiversity. Apart from natural causes, human activities, both directly and indirectly are today's main reason for habitat loss and biodiversity loss. Fragmentation and degradation due to agricultural practices, extraction (mining, fishing, logging, harvesting) and development (settlements, industrial and associated infrastructures) leads to habitat loss and fragmentation leads to formation of isolated, small and scattered populations and as endangered species.

Some of the other threats include specialised diet, specialized habitat requirement, large size, small population size, limited geographic distribution and high economic or commercial value. Large mammals by virtue of their size require larger areas to obtain the necessities of life - food, cover, mates than do smaller mammals. Individual home range of Lion can be about 100 square Kilometer. Mammals have specialized dietary needs such as carnivores, frugivores and the need to forage over much larger areas than general dietary herbivores and omnivores. Mammals also have low reproductive output other than small rodents.

Do You Know?

The interrelationship and interdependence of all living components in a system can be seen from the example of the fruit bats of Guam (South East Asia). The fruit bats are a delicacy here, and hence their population has dwindled which is not surprising. What is surprising is that local fruit production has got affected as it was identified that the bats served as pollinators. Hence there is a need for conservation of diversity as that could avert such situations.

11.5 Causes of Biodiversity Loss

Major Causes for Biodiversity Decline

• Habitat loss, fragmentation and destruction (affects about 73 percentage of all species)
• Pollution and pollutants (smog, pesticides, herbicides, oil slicks, GHGs)
• Climate change
• Introduction of alien or exotic species
• Over exploitation of resources (poaching, indiscriminate cutting of trees, over fishing, hunting, mining)
• Intensive agriculture and aquacultural practices
• Hybridization between native and nonnative species and loss of native species
• Natural disasters (Tsunami, forest fire, earth quake, volcanoes)
• Industrialization, Urbanization, infrastructure development, Transport – Road and Shipping activity, communication towers, dam construction, unregulated tourism and monoculture are common area of specific threats
• Co-extinction

Habitat Loss

Development of human society is inevitable. Natural habitats are destroyed for the purpose of settlement, agriculture, mining, industries and construction of highways. As a result species are forced to adapt to the changes in the environment or move to other places. If not, they become victim to predation, starvation, disease and eventually die or results in human animal conflict.

Over population, urbanization, industrialization and agricultural advancements require additional land, water and raw materials every year. This is made possible only through fragmentation or destruction of natural habitats by filling wetlands, ploughing grasslands, cutting down trees, forest, desilting rivers, constructing transport ways, caving mountains, extracting ores, changing the course of rivers and filling of seashore.

The most dramatic example of habitat loss comes from the tropical rainforests – 14% of the earth's land surface once covered by these tropical forests, is not more than 6% now. The Amazon rainforest, a vast area, harbouring millions of species, also called "Lungs of the planet" is destroyed and being replaced for agriculture and human settlements. 90% of New Zealand's wetlands have been destroyed and cleared for cultivating soya beans and raising grass for beef cattle. Kodaikanal and Nilgiri hills of Tamil Nadu have been destroyed rapidly for human occupancy. Loss of habitat results in annihilation of plants, microorganisms and forcing out animals from their habitats.

Where are the Sparrows?

Common Sparrows are going extinct because of mindless urbanization. They are losing not just their natural habitats but also the essential human touch they need and thrive upon. The population of sparrows is dwindling due to the use of packed food, insecticides in farming and changing lifestyles, and match box-styled architecture resulting in an inadequate availability of food and shelter for the birds. Unlike pigeons that can make nests on ledges, sparrows need cavities to build their nests.

Habitat Fragmentation

Habitat fragmentation is the process where a large, continuous area of habitat is both, reduced in area and divided into two or more fragments. Fragmentation of habitats like forest land into crop lands, orchard lands, plantations, urban areas, industrial estates, transport and transit systems has resulted in the destruction of complex interactions amongst species (food chain and webs), destruction of species in the cleared regions, annihilation of species restricted to these habitats (endemic) and decreased biodiversity in the habitat fragments. Animals requiring large territories such as mammals and birds are severely affected. The elephant corridors and migratory routes are highly vulnerable. The dwindling of many well-known birds (sparrows) and animals can be attributed to this.

Over Exploitation

We depend on nature for our basic needs such as food and shelter. However, when the need becomes greed, it leads to over exploitation of natural resources. Excessive exploitation of a species, reduces the size of its population to such a level that it becomes vulnerable to extinction. Dodo, passenger pigeon and Steller's sea cow have become extinct in the last 200-300 years due to over exploitation by humans. Overfishing due to population pressure leads to many marine fish populations declining around the world.

Exotic Species Invasion

Exotic species (non-native; alien) are organisms often introduced unintentionally or deliberately for commercial purpose, as biological control agents and other uses. They often become invasive and drive away the local species and is considered as the second major cause for extinction of species. Exotic species have proved harmful to both aquatic and terrestrial ecosystems.

Tilapia fish (Jilabi kendai) (Oreochromis mosambicus) introduced from east coast of South Africa in 1952 for its high productivity into Kerala's inland waters, became invasive, due to which the native species such as Puntius dubius and Labeo kontius face local extinction. The illegal introduction of the African catfish Claries gariepinus for aquaculture purposes is posing a threat to the indigenous cat fishes in our rivers. The introduction of the Nile Perch, a predatory fish into Lake Victoria in East Africa led to the extinction of an ecologically unique assemblage of more than 200 nature species of cichlid fish in the lake.

Global Climate Changes

Industrialization is a major contributor to climate change and a major threat to biodiversity. Energy drives our industries, which is provided by burning of fossil fuels. This increases the emission of CO₂, a GHG, leading to climate change. Due to large scale deforestation, the emitted CO₂ cannot be absorbed fully, and its concentration in the air increases. Climate change increases land and ocean temperature, changes precipitation patterns and raises the sea level. This in turn results in melting of glaciers, water inundation, less predictability of weather patterns, extreme weather conditions, outbreak of diseases, migration of animals and loss of trees in forest. Thus, climate change is an imminent danger to the existing biodiversity (Figure 11.4).

Shifting or Jhum Cultivation (Slash and Burn Agriculture)

In shifting cultivation, plots of natural tree vegetation are burnt away and the cleared patches are farmed for 2 to 3 seasons, after which their fertility reduces to a point where crop production is no longer profitable. The farmer then abandons this patch and cuts down a new patch of forest trees elsewhere for crop production. This system is practiced in north-eastern regions of India. When vast areas are cleared and burnt, it results in loss of forest cover, pollution and discharge of CO₂ which in turn attributes to loss of habitat and climate change which has an impact on the faunal diversity of that region.

Coextinctions

Coextinction of a species is the loss of a species as a consequence of the extinction of another. (Example: orchid bees and forest trees by cross pollination). Extinction of one will automatically cause extinction of the other. Another example for co-extinction is the connection between Calvaria tree and the extinct bird of Mauritius Island, the Dodo. The Calvaria tree is dependent on the Dodo bird for completion of its life cycle. The mutualistic association is that the tough horny endocarp of the seeds of Calvaria tree are made permeable by the actions of the large stones in bird's gizzard and digestive juices thereby facilitating easier germination. The extinction of the Dodo bird led to the imminent danger of the Calvaria tree coextinction.

Intensive Agriculture

Spread of agriculture is sometimes at the cost of wetlands, grasslands and forests. Intensive agriculture is based on a few high yielding varieties. As a result, there is reduction in the genetic diversity. It also increases vulnerability of the crop plants to sudden attack by pathogens and pests. There are only few varieties of traditional paddy strains today due to use of hybrid varieties in Tamil Nadu.

11.5.1 Loss of Biodiversity

Species have been evolving and dying out (extinction) ever since the origin of life. However, species are now becoming extinct at a faster rate. This is destabilizing the ecological stability and the distribution of biological diversity on earth. Human activities greatly contribute to the loss of biodiversity. Natural resources such as land, water and organisms are indiscriminately exploited by human beings.

According to the Convention of Biological Diversity, direct and indirect human activities have a detrimental effect on biodiversity. Direct human activities like change in local land use, species introduction or removal, harvesting, pollution and climate change contribute a greater pressure on loss of biodiversity. Indirect human drivers include demographic, economic, technological, cultural and religious factors.

Even though new species are being discovered, there is little hope for adding new species through speciation into the biodiversity treasure. Monsoon failure, global warming, depletion in ozone layer, landslides in hilly states, pollution are a few indirect effects of human activities which results in the loss of biodiversity. IUCN Red List (2004) documents the extinction of 784 species in the 500 years.

Impact of Biodiversity Loss

It is estimated that the current rate of biodiversity loss is 100 to 1000 times higher than the naturally occurring extinction rate and is still expected to grow in the future. This loss of biodiversity has an immense impact on plant, animal and human life. The negative effects include dramatic influence on the food web. Even reduction in one species can adversely affect the entire food chain which further leads to an overall reduction in biodiversity. Reduced biodiversity leads to immediate danger for food security by reducing ecosystem services.

11.5.2 Hotspots

Hotspots are areas characterized with high concentration of endemic species (the organisms which are exclusively restricted to a given area) experiencing unusual rapid rate of habitat modification loss. Norman Myers defined hot spots as "regions that harbour a great diversity of endemic species and at the same time, have been significantly impacted and altered by human activities."

Criteria for a Hotspot

• A hotspot is a region that supports at least 1500 endemic vascular plant species (0.5 percentage of the global total)
• Has lost more than 70 percentage of its original vegetation

There are 36 biodiversity hotspots in the world. India is home to four biodiversity hotspots (as per ENVIS). They are:

1. Himalaya (the entire Indian Himalayan region)
2. Western Ghats
3. Indo-Burma: includes entire North-eastern India, except Assam and Andaman group of Islands (and Myanmar, Thailand, Vietnam, Laos, Cambodia and Southern China)
4. Sundalands: includes Nicobar group of Islands (and Indonesia, Malaysia, Singapore, Brunei, Philippines)

11.5.3 Endangered Organisms

A species that has been categorized as very likely to become extinct is an Endangered species. Endangered (EN), as categorized by the International Union for Conservation of Nature (IUCN) Red List, is the second most severe conservation status for wild populations in the IUCN scheme after Critically Endangered (CR). In 1998 there were 1102 animal and 1197 plant species in the IUCN Red List. In 2012, the list features 3079 animal and 2655 plant species as endangered (EN) worldwide.

One more species goes extinct...

George the tree snail (Achatinella apexfulva) died on January 1, 2019, at the age of 14. He was the last snail of his species, and is emblematic of the loss of native Hawaiian molluscs.

11.5.4 Extinction

Species is considered extinct when none of its members are alive anywhere in the world. If individuals of a species remain alive only in captivity or other human controlled conditions, the species is said to be extinct in the wild. In both of these situations, the species would be considered globally extinct. A species is considered to be locally extinct when it is no longer found in an area it once inhabited but is still found elsewhere in the wild.

In the 450 million years of life on Earth, there had been 5 mass extinctions, which had eliminated at least 50% of the species of flora and fauna on the globe. The extinction of species is mainly due to drastic environmental changes and population characteristics.

Three Types of Extinctions

1. Natural extinction: It is a slow process of replacement of existing species with better adapted species due to changes in environmental conditions, evolutionary changes, predators and diseases. A small population can get extinct sooner than the large population due to inbreeding depression (less adaptivity and variation).
2. Mass extinction: The earth has experienced quite a few mass extinctions due to environmental catastrophes. A mass extinction occurred about 225 million years ago during the Permian, where 90% of shallow water marine invertebrates disappeared.
3. Anthropogenic extinctions: These are abetted by human activities like hunting, habitat destruction, over exploitation, urbanization and industrialization. Some examples of extinctions are Dodo of Mauritius and Steller's sea cow of Russia. Amphibians seem to be at higher risk of extinction because of habitat destruction. The most serious aspect of the loss of biodiversity is the extinction of species. The unique information contained in its genetic material (DNA) and the niche it possesses are lost forever.

Project Tiger

The Government of India launched the 'Project Tiger' in 1973 to protect our national animal. From 9 tiger reserves since its inception, the Project Tiger coverage has increased to 50 at present. Project Tiger is an ongoing Centrally Sponsored Scheme of the Ministry of Environment and Forests, providing central assistance to the states for tiger conservation in designated tiger reserves. Project Tiger was launched in the Jim Corbett National Park, Uttarakhand in 1973. The project ensures a viable population of Bengal tigers in their natural habitats, protecting them from extinction and preserving areas of biological importance as a natural heritage. The National Tiger Conservation Authority (NTCA) is a statutory body of the Ministry, created under the Wildlife (Protection) Act, 1972. India holds over half the world's tiger population. According to the latest tiger census report released on 20th January 2015 by NTCA, the current tiger population is estimated at 2,212.

11.6 IUCN

The International Union for Conservation of Nature (IUCN) is an organization working in the field of nature conservation and sustainable use of natural resources. It was established in 1948 and located at Gland VD, Switzerland. It is involved in data gathering and analysis, research, field projects and education on conservation, sustainable development and biodiversity.

IUCN mission is to influence, encourage and assist societies throughout the world to conserve nature and to ensure that any use of natural resources is equitable and ecologically sustainable. It influences governments and industries through partnerships by providing information and advice. The organization collects, compiles and publishes the IUCN red list of threatened species and their conservation status in the world. It plays a vital role in the implementation of several international conventions on nature conservation and biodiversity.

Red Data Book

Red Data book or Red list is a catalogue of taxa facing risk of extinction. IUCN – International Union of Conservation of Nature and Natural Resources, which is renamed as WCU – World Conservation Union (Morges Switzerland) maintains the Red Data book. The concept of Red list was mooted in 1963.

Purpose of Red List

• To create awareness on the degree of threat to biodiversity
• Identification and documentation of species at high risk of extinction
• Provide global index on declining biodiversity
• Preparing conservation priorities and help in conservation of action
• Information on international agreements on conservation of biological diversity

Red List Categories of Species

1. Extinct
2. Extinct in wild
3. Critically Endangered
4. Endangered
5. Vulnerable
6. Lower risk
7. Data deficiency
8. Not evaluated

11.7 Biodiversity and its Conservation

"The natural resources of the Earth, including air, water, land, flora and fauna of natural ecosystems must be safeguarded for the benefit of the present and future generations through careful planning and management, as appropriate." – Principle of the Stockholm Declaration, 1972.

The large-scale loss of biodiversity and its global impact makes conservation the need of the hour. Conservation of biodiversity is protection and scientific management of biodiversity so as to maintain it at its optimum level and derive sustainable benefits for the present as well as future generations. It aims to protect species from extinction and their habitats and ecosystems from degradation.

General Strategies in Conservation

• Identify and protect all threatened species
• Identify and conserve in protected areas the wild relatives of all the economically important organisms
• Identify and protect critical habitats for feeding, breeding, nursing, resting of each species
• Air, water and soil should be conserved on priority basis
• Wildlife Protection Act should be implemented

There are two aspects of conservation strategies:

1. In-situ conservation
2. Ex-situ conservation

11.7.1 In-situ Conservation (Conservation in the Natural Habitat)

This is the conservation of genetic resources through their protection within a natural or manmade ecosystem in which they occur. It is conservation and protection of the whole ecosystem and its biodiversity at all levels in order to protect the threatened species. Maximum protection of biodiversity hotspots – regions with very high levels of species richness. Although all the biodiversity hotspots together cover less than 2 percent of the earth land area, the number of species they harbour is extremely high and protection of these hotspots could reduce the ongoing mass extinction.

Protected Areas

These are biogeographical areas where biological diversity along with natural and cultural resources is protected, maintained and managed through legal measures. Protected areas include national parks, wild life sanctuaries, community reserves and biosphere reserves. World Conservation monitoring centre has recognized 37,000 protected areas world-wide. India has about 771 protected areas covering 162099 km² comprising of National Parks (104), Wild Life Sanctuaries (544), biosphere reserves (18) and several sacred groves.

National Parks (NP)

It is a natural habitat that is notified by the state government to be constituted as a National Park due to its ecological, faunal, floral, geomorphological, or zoological association of importance. No human activity is permitted inside the national park except the activities permitted by the Chief Wildlife Warden of the state under the conditions given in Chapter 4, of the Wildlife Protection Act (WPA) 1972.

Table 11.2 National Parks in Tamil Nadu

National Parks in Tamil Nadu	Year of Establishment	District(s)
Guindy National Park	1977	Chennai
Gulf of Mannar Marine National Park	1986	Ramanathapuram and Tuticorin
Indira Gandhi (Annamalai) National Park	1976	Coimbatore
Mudumalai National Park	1940	Nilgiris
Mukurthi National Park	2001	Nilgiris

There are 104 existing national parks in India covering an area of 40,501 km², which is 1.23 percentage of the geographical area of the country (National Wildlife Database, Aug. 2018). National Park is an area which is strictly reserved for the betterment of wildlife and biodiversity and where activities like development, forestry, poaching, hunting, grazing and cultivation are not permitted. They are large areas of scenic and national beauty maintained for scientific, educational and recreational use. They are not used for commercial extraction of resources. Kaziranga National park is a protected area for the One Horned Rhinoceros in Assam.

Wild Life Sanctuaries (WLS)

Any area other than the area comprised with any reserve forest or the territorial waters can be notified by the State Government to constitute as a sanctuary if such area is of adequate ecological, faunal, floral, geomorphological, natural or zoological significance. This is for the purpose of protecting endangered faunal species. Some restricted human activities are allowed inside the Sanctuary area, details of which are given in Chapter IV, of the Wildlife Protection Act (WPA) 1972. Ecotourism is permitted, as long as animal life is undisturbed.

There are 544 existing wildlife sanctuaries in India covering an area of 118918 km², which is 3.62 percentage of the geographical area of the country (National Wildlife Database, 2017). Sanctuaries are tracts of land where wild animals and fauna can take refuge without being hunted or poached. Other activities like collection of forest products, regulated harvesting of timber, private ownership of land are permitted. Periyar wild life sanctuary in Kerala is famous for the Indian Tiger and Asiatic Elephant.

Table 11.3 Wild Life Sanctuaries in Tamil Nadu

Prominent WLS in Tamil Nadu	Year of Establishment	Districts
Vedanthangal Lake Birds Wild Life Sanctuary	1936	Chengalpet
Mudumalai Wild Life Sanctuary	1942	Nilgiris
Point Calimere Wild Life Sanctuary	1967	Nagapattinam
Indira Gandhi (Annamalai) Wild Life Sanctuary	1976	Coimbatore
Mundanthurai Wild Life Sanctuary	1988	Tirunelveli

The Madras Crocodile Bank Trust

The Madras Crocodile Bank Trust and Centre for Herpetology was the brain child of the legendary Romulus Whitaker and a handful of like-minded conservation visionaries, who began work on the facility in 1976. It aimed to save India's dwindling crocodilian population. The mission is to promote the conservation of reptiles and amphibians and their habitats through education, scientific research and capture breeding. The crocodile bank remains a world leader in the field of frontline conservation and the preservation of natural landscapes. The Crocodile Bank currently consists of a large reptile park near Chennai and several field projects located throughout the subcontinent reaching as far as the Nicobar Islands. About half a million people visit the bank every year, making it one of the most popular tourist attractions along the East Coast Road.

Biosphere Reserve (BR)

Biosphere Reserve (BR) is an international designation by UNESCO for representative parts of natural and cultural landscapes extending over large area of terrestrial or coastal or marine ecosystems or a combination thereof. BRs are designated to deal with the conservation of biodiversity, economic and social development and maintenance of associated cultural values. Biosphere Reserves are thus special environments for both people and nature and are living examples of how human beings and nature can co-exist while respecting each other's needs.

The Biosphere Reserve Programme is guided by UNESCO's Man and Biosphere (MAB) programme, as India is a signatory to the landscape approach supported by MAB programme. The scheme called Biosphere Reserve was implemented by the Government of India in 1986. There are 18 Biosphere Reserves in the country. Agasthyamalai (Karnataka - Tamil Nadu - Kerala), Nilgiri (Tamil Nadu - Kerala), Gulf of Mannar (Tamil Nadu) are the BRs notified in Tamil Nadu.

Arignar Anna Zoological Park, Vandalur

Arignar Anna Zoological Park is spread over an area of 602 hectares of Reserve Forest at Vandalur, Chennai. It is one of the largest zoo in South East Asia in terms of area. The Zoological Park exhibits different classes of animals – it has around 2500 wild animals of nearly 180 species which includes Mammals, Birds and Reptiles. 34 years since its establishment, the Zoological Park has emerged as a successful ex-situ conservation centre and a captive breeding centre for many endangered species like Royal Bengal Tiger, Lion Tailed Macaque, Nilgiri Langur, Gray Wolf, etc. The Zoo has many attractive features like Butterfly Park, Children's Park, Walk Through Aviary, Lion & Deer Safari, Forest Museum, Interpretation centre, etc., which attracts more than 21 lakh visitors every year. The Zoo has strengthened its protection by means of installing CCTV Cameras for both visitors and animal management under the name of Zoo e-Eye. 24×7 Animal Live Streaming was introduced for the benefit of the visitors for the first time in the world. Vandalur Zoo Mobile Application was introduced to provide services to the visitors like facility to book tickets, Zoo navigation, Animal information in text and audio format. Digital payments at ticket counters are also available. The Zoo school has been involved in education and outreach programmes. One such successful programme is 'Zoo Ambassador' which is been conducted for school children. In the year 2018, more than 400 students were trained and titled as Zoo Ambassadors. The Zoo also has a Rescue Centre which accommodates rescued wild animals and treats them to come out of stress.

Source: Director, Arignar Anna Zoological Park, Vandalur, Chennai

Sacred Groves

A sacred grove or sacred woods are any grove of trees that are of special religious importance to a particular culture. Sacred groves feature in various cultures throughout the world. The examples of sacred groves are Alagar hills in Tamil Nadu, Khasi and Jaintia hills in Meghalaya and Aravalli hills of Rajasthan.

11.7.2 Ex-Situ Conservation

It is conservation of selected rare plants or animals in places outside their natural homes. It includes offsite collections and gene banks.

Offsite Collections

They are live collections of wild and domesticated species in Botanical gardens, Zoological parks, Wildlife safari parks, Arborata (gardens with trees and shrubs). The organisms are well maintained for captive breeding programmes. As a result, many animals which have become extinct in the world continue to be maintained in Zoological Parks. As the number increases in captive breeding, the individuals are selectively released in the wild. In this way the Indian crocodile and gangetic dolphin have been saved from extinction.

Gene Banks

Gene banks are a type of biorepository which preserve genetic materials. Seeds of different genetic strains of commercially important plants can be stored in long periods in seed banks, gametes of threatened species can be preserved in viable and fertile condition for long periods using cryopreservation techniques. However, it is not economically feasible to conserve all biological wealth and all the ecosystems. The number of species required to be saved from extinction far exceeds the conservation efforts.

Table 11.4 Difference between In-situ and Ex-situ Conservation

In-situ Conservation	Ex-situ Conservation
It is the on-site conservation or the conservation of genetic resources in natural populations of plant or animal species.	This is a conservation strategy which involves placing of threatened animals and plants in special care locations for their protection.
It is the process of protecting an endangered plant or animal species in its natural habitat, either by protecting or restoring the habitat itself, or by defending the species from predators.	It helps in recovering populations or preventing their extinction under simulated conditions that closely resemble their natural habitats.
National Parks, Biosphere Reserve, Wild Life Sanctuaries form in-situ conservation strategies.	Zoological parks and Botanical gardens are common ex-situ conservation programs.

Summary

Summary

Biodiversity is the variety of all life on Earth, encompassing genetic, species and ecosystem diversity. Today's biodiversity is the fruit of billions of years of evolution, shaped by natural processes and, increasingly, by the influence of humans. To date, about two million species have been identified on Earth. Biodiversity supplies a large number of goods and services that sustain human life, including the provision of food, fuel and building materials; purification of air and water; stabilization and moderation of the earth's climate; moderation of floods, droughts, temperature extremes and wind forces; generation and renewal of soil health; maintenance of genetic resources as inputs to crop varieties and livestock breeds, medicines, and other products; and cultural, recreational and aesthetic benefits.

Over the past few hundred years, biodiversity has faced major challenges, including a growing demand for biological resources caused by population growth and increased consumption. This increased exploitation of biological resources has resulted in the loss of species at levels currently estimated to be 100 times faster than the natural rate of loss prior to significant human intervention. Though many species were lost and new ones formed, it is likely we will lose all this natural wealth in less than two centuries, if the present rate of biodiversity losses persist.

The biodiversity and its conservation is the important global issue of international concern. Recognition of this problem has made scientists and policy makers to work and develop mechanisms to document, conserve and sustainably use biodiversity. The younger generation should be made to realize the critical state of biodiversity today and volunteer to protect and conserve it, so as to enable the future generations get to enjoy the benefits of Nature.

Evaluation

Exercise MCQ Questions

1. Which of the following region has maximum biodiversity?

a) Taiga b) Tropical forest c) Temperate rain forest d) Mangroves

2. Conservation of biodiversity within their natural habitat is:

a) Insitu conservation b) Exsitu conservation c) In vivo conservation d) In vitro conservation

3. Which one of the following is not coming under insitu conservation?

a) Sanctuaries b) Natural parks c) Zoological park d) Biosphere reserve

4. Which of the following is considered a hotspot of biodiversity in India?

a) Western Ghats b) Indo-Gangetic plain c) Eastern Himalayas d) A and C

5. The organization which published the red list of species is:

a) WWF b) IUCN c) ZSI d) UNEP

6. Who introduced the term biodiversity?

a) Edward Wilson b) Walter Rosen c) Norman Myers d) Alice Norman

7. Which of the following forests is known as the lungs of the planet earth?

a) Tundra forest b) Rain forest of north east India c) Taiga forest d) Amazon rain forest

8. Which one of the following are at high risk of extinction due to habitat destruction?

a) Mammals b) Birds c) Amphibians d) Echinoderms

9. Assertion: The Environmental conditions of the tropics are favourable for speciation and diversity of organisms.
Reason: The climate, seasons, temperature, humidity and photoperiod are more or less stable and congenial.

a) Both Assertion and Reason are true and Reason explains Assertion correctly. b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion. c) Assertion is true, but Reason is false. d) Both Assertion and Reason are false. Exercise 10. Define the following

a. Species richness

b. Endemism

Exercise 11. How many hotspots are there in India? Name them. Exercise 12. What are the three levels of biodiversity? Exercise 13. Name the active chemical found in the medicinal plant Rauwolfia vomitoria. What type of diversity does it belong to? Exercise 14. "Amazon forest is considered to be the lungs of the planet" – Justify this statement. Exercise 15. What is 'Red data book'? Mention its purposes. Exercise 16. Compare and Contrast the insitu and exsitu conservation. Exercise 17. What are called endangered species? Exercise 18. Why do we find a decrease in biodiversity distribution, if we move from the tropics towards the poles? Exercise 19. What are the factors that drive habitat loss? Exercise 20. Alien species invasion is a threat to endemic species – substantiate this statement. Exercise 21. Mention the major threats to biodiversity caused by human activities. Explain. Exercise 22. What is mass extinction? Will you encounter one such extinction in the near future? Enumerate the steps to be taken to prevent it. Exercise 23. In north eastern states, the jhum cultivation is a major threat to biodiversity – substantiate the statement. Exercise 24. List out the various causes for biodiversity losses. Exercise 25. How can we contribute to promote biodiversity conservation? Exercise 26. Write a note on the following

i) Protected areas

ii) Wild life sanctuaries

ICT Corner: Biodiversity and its Conservation

Let us go out for a virtual exhibition, to know about 30 endangered animals.

Procedure

• Step 1: Type the URL or scan the QR code to open the activity page. Click "Explore the exhibition" to start the exhibition.
• Step 2: Find the species name below the figure (Ex: Helmeted Hornbill). Find a grey dot right next to the name. Click the same to know about its extinction.
• Step 3: Click "<" on the left top of this page to play a video about the same species. Click "x" to run to the homepage.
• Step 4: On the left "top first" option to load all the species. Middle square in a circle is for slide show of all the species.
• Step 5: On the right of the page, find ^ and down button to move on from one to the next.

URL: http://www.species-in-pieces.com/

Pictures are indicative only. Allow flash player.

Book-back Exercises — Questions & Answers

Answers generated strictly from the Samacheer Kalvi textbook content. Attempt each question first, then click "Show Answer" to check.

I. Choose the Correct Answer

1. Which of the following region has maximum biodiversity?

a) Taiga b) Tropical forest c) Temperate rain forest d) Mangroves

Answer: b) Tropical forest

Explanation: Tropics harbour more biodiversity than temperate or polar regions. Environmental conditions of the tropics are favourable not only for speciation but also for supporting both variety and number of organisms.

2. Conservation of biodiversity within their natural habitat is

a) Insitu conservation b) Exsitu conservation c) In vivo conservation d) In vitro conservation

Answer: a) Insitu conservation

Explanation: In-situ conservation is the conservation of genetic resources through their protection within a natural or manmade ecosystem in which they occur.

3. Which one of the following is not coming under insitu conservation?

a) Sanctuaries b) Natural parks c) Zoological park d) Biosphere reserve

Answer: c) Zoological park

Explanation: National Parks, Biosphere Reserves and Wild Life Sanctuaries form in-situ conservation strategies, whereas Zoological parks are common ex-situ conservation programmes.

4. Which of the following is considered a hotspot of biodiversity in India?

a) Western ghats b) Indo-gangetic plain c) Eastern Himalayas d) A and C

Answer: d) A and C

Explanation: India is home to four biodiversity hotspots: Himalaya (entire Indian Himalayan region), Western Ghats, Indo-Burma and Sundalands. Both Western Ghats and the Himalaya (which includes Eastern Himalayas) are hotspots.

5. The organization which published the red list of species is

a) WWF b) IUCN c) ZSI d) UNEP

Answer: b) IUCN

Explanation: The IUCN (International Union for Conservation of Nature) collects, compiles and publishes the IUCN red list of threatened species and their conservation status in the world.

6. Who introduced the term biodiversity?

a) Edward Wilson b) Walter Rosen c) Norman Myers d) Alice Norman

Answer: b) Walter Rosen

Explanation: The term biodiversity was introduced by Walter Rosen (1986). Edward Wilson later popularized the term to describe diversity at all levels of biological organization.

7. Which of the following forests is known as the lungs of the planet earth?

a) Tundra forest b) Rain forest of north east India c) Taiga forest d) Amazon rain forest

Answer: d) Amazon rain forest

Explanation: The Amazon rainforest, a vast area harbouring millions of species, is also called "Lungs of the planet."

8. Which one of the following are at high risk of extinction due to habitat destruction?

a) Mammals b) Birds c) Amphibians d) Echinoderms

Answer: c) Amphibians

Explanation: Amphibians seem to be at higher risk of extinction because of habitat destruction, as stated in the chapter.

9. Assertion: The Environmental conditions of the tropics are favourable for speciation and diversity of organisms.
Reason: The climate, seasons, temperature, humidity and photoperiod are more or less stable and congenial.

a) Both Assertion and Reason are true and Reason explains Assertion correctly. b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion. c) Assertion is true, but Reason is false. d) Both Assertion and Reason are false.

Answer: a) Both Assertion and Reason are true and Reason explains Assertion correctly.

Explanation: The chapter states that environmental conditions of the tropics are favourable for speciation and supporting both variety and number of organisms, and that climate, seasons, temperature, humidity and photoperiods are more or less stable and encourage both variety and numbers.

II. Answer Briefly

10. Define the following: a. Species richness   b. Endemism

Answer:

a. Species richness: The number of species per unit area at a specific time is called species richness, which denotes the measure of species diversity. The more the number of species in an area the more is the species richness.

b. Endemism: Endemic species are organisms which are exclusively restricted to a given area. Endemism is a crucial indicator of richness and is characteristic of biodiversity hotspots, which are areas with high concentration of endemic species experiencing unusual rapid rate of habitat modification and loss.

11. How many hotspots are there in India? Name them.

Answer: India is home to four biodiversity hotspots (as per ENVIS). They are: (a) Himalaya – the entire Indian Himalayan region, (b) Western Ghats, (c) Indo-Burma – includes entire North-eastern India except Assam and Andaman group of Islands, and (d) Sundalands – includes Nicobar group of Islands.

12. What are the three levels of biodiversity?

Answer: The three levels of biodiversity are: (1) Genetic diversity – differences in genetic make-up between and within species; (2) Species diversity – variety in number and richness of species in any habitat; and (3) Community or Ecosystem diversity – the variety of habitats, biotic communities and ecological processes in the biosphere.

13. Name the active chemical found in the medicinal plant Rauwolfia vomitoria. What type of diversity does it belong to?

Answer: The active chemical found in Rauwolfia vomitaria is reserpine. Rauwolfia vomitaria growing in different ranges of the Himalayas shows differences in the potency and concentration of reserpine due to genetic diversity.

14. "Amazon forest is considered to be the lungs of the planet" – Justify this statement.

Answer: The Amazon rainforest is a vast area harbouring millions of species and is called the "Lungs of the planet." Forests are essential for rainfall, temperature regulation and CO₂ absorption, which regulate climate. However, the Amazon is being destroyed and replaced by agriculture and human settlements, reducing its ability to absorb CO₂ and regulate the atmosphere.

15. What is 'Red Data Book'? Mention its purposes.

Answer: Red Data Book or Red List is a catalogue of taxa facing risk of extinction, maintained by IUCN (renamed as WCU – World Conservation Union). The concept was mooted in 1963. Its purposes are: (1) To create awareness on the degree of threat to biodiversity; (2) Identification and documentation of species at high risk of extinction; (3) Provide global index on declining biodiversity; (4) Preparing conservation priorities and helping in conservation action; and (5) Information on international agreements on conservation of biological diversity.

16. Compare and Contrast the insitu and exsitu conservation.

Answer:

In-situ Conservation: It is the on-site conservation or the conservation of genetic resources in natural populations of plant or animal species. It is the process of protecting an endangered plant or animal species in its natural habitat, either by protecting or restoring the habitat itself. National Parks, Biosphere Reserves and Wild Life Sanctuaries are in-situ conservation strategies.

Ex-situ Conservation: This is a conservation strategy which involves placing of threatened animals and plants in special care locations for their protection. It helps in recovering populations or preventing their extinction under simulated conditions that closely resemble their natural habitats. Zoological parks and Botanical gardens are common ex-situ conservation programmes.

17. What are called endangered species?

Answer: A species that has been categorized as very likely to become extinct is an Endangered species. Endangered (EN), as categorized by the IUCN Red List, is the second most severe conservation status for wild populations in the IUCN scheme after Critically Endangered (CR). In 2012, the IUCN Red List features 3079 animal and 2655 plant species as endangered worldwide.

18. Why do we find a decrease in biodiversity distribution, if we move from the tropics towards the poles?

Answer: There is an increasing diversity from the poles towards the equator (latitudinal gradient). Harsh conditions exist in temperate areas during cold seasons while very harsh conditions prevail for most of the year in polar regions. The tropics have stable climate, seasons, temperature, humidity and photoperiods that encourage both variety and numbers, whereas these conditions become unfavourable as we move towards the poles, reducing species diversity.

19. What are the factors that drive habitat loss?

Answer: The factors that drive habitat loss include: over population, urbanization, industrialization and agricultural advancements requiring additional land, water and raw materials. This is achieved through filling wetlands, ploughing grasslands, cutting down trees/forests, desilting rivers, constructing transport ways, caving mountains, extracting ores, changing the course of rivers and filling of seashore. Development for settlement, agriculture, mining, industries and construction of highways also drive habitat loss.

20. Alien species invasion is a threat to endemic species – substantiate this statement.

Answer: Exotic (alien/non-native) species are organisms often introduced unintentionally or deliberately. They often become invasive and drive away local species, and are considered the second major cause of extinction. For example, Tilapia fish (Oreochromis mosambicus) introduced into Kerala's inland waters became invasive, causing native species like Puntius dubius and Labeo kontius to face local extinction. The introduction of Nile Perch into Lake Victoria led to the extinction of more than 200 native cichlid fish species.

III. Answer in Detail

21. Mention the major threats to biodiversity caused by human activities. Explain.

Answer: The major threats to biodiversity caused by human activities include:

1. Habitat Loss and Fragmentation: Natural habitats are destroyed for settlement, agriculture, mining, industries and highways. Fragmentation of habitats results in the destruction of complex species interactions and annihilation of endemic species. Affects about 73% of all species.

2. Over Exploitation: Excessive exploitation of species reduces population to levels vulnerable to extinction. Dodo, passenger pigeon and Steller's sea cow became extinct due to over exploitation. Overfishing leads to many marine fish populations declining.

3. Exotic Species Invasion: Alien species introduced unintentionally or deliberately become invasive, driving away local species. This is the second major cause of extinction (e.g., Tilapia in Kerala, Nile Perch in Lake Victoria).

4. Global Climate Change: Burning of fossil fuels increases CO₂ emissions, causing climate change. This increases land and ocean temperature, changes precipitation patterns, raises sea level, and results in melting of glaciers and loss of biodiversity.

5. Pollution: Smog, pesticides, herbicides, oil slicks and greenhouse gases degrade habitats and harm species directly.

6. Intensive Agriculture: Based on a few high-yielding varieties, it reduces genetic diversity and increases vulnerability of crop plants to sudden attack by pathogens and pests.

22. What is mass extinction? Will you encounter one such extinction in the near future? Enumerate the steps to be taken to prevent it.

Answer: Mass Extinction: The earth has experienced quite a few mass extinctions due to environmental catastrophes. A mass extinction occurred about 225 million years ago during the Permian, where 90% of shallow water marine invertebrates disappeared. In the 450 million years of life on Earth, there had been 5 mass extinctions, which had eliminated at least 50% of the species of flora and fauna on the globe. The current rate of biodiversity loss is 100 to 1000 times higher than the naturally occurring extinction rate.

Yes, we may encounter such extinction in the near future if current trends persist. The WWF states that "The world is currently undergoing a very rapid loss of biodiversity comparable with the great mass extinction events."

Steps to prevent it: (1) Identify and protect all threatened species; (2) Identify and conserve protected areas and wild relatives of economically important organisms; (3) Protect critical habitats for feeding, breeding, nursing and resting; (4) Conserve air, water and soil on priority basis; (5) Implement the Wildlife Protection Act strictly; (6) Establish national parks, biosphere reserves and wildlife sanctuaries (in-situ conservation); (7) Maintain ex-situ conservation through zoological parks, botanical gardens and gene banks; (8) Reduce habitat destruction, over exploitation and pollution; (9) Control introduction of alien/exotic species.

23. In north eastern states, the jhum cultivation is a major threat to biodiversity – substantiate the statement.

Answer: Jhum cultivation (Slash and burn agriculture) is practiced in north-eastern regions of India. In shifting cultivation, plots of natural tree vegetation are burnt away and the cleared patches are farmed for 2 to 3 seasons, after which their fertility reduces to a point where crop production is no longer profitable. The farmer then abandons this patch and cuts down a new patch of forest elsewhere for crop production. When vast areas are cleared and burnt, it results in loss of forest cover and pollution. The discharge of CO₂ contributes to climate change, which in turn causes loss of habitat. This has a severe impact on the faunal diversity of the region. The north-eastern region also represents a biodiversity hotspot and a biogeographical gateway for much of India's fauna and flora, making jhum cultivation particularly damaging to the rich biodiversity of that area.

24. List out the various causes for biodiversity losses.

Answer: The major causes for biodiversity decline are:

1. Habitat loss, fragmentation and destruction (affects about 73% of all species)

2. Pollution and pollutants (smog, pesticides, herbicides, oil slicks, GHGs)

3. Climate change

4. Introduction of alien or exotic species

5. Over exploitation of resources (poaching, indiscriminate cutting of trees, over fishing, hunting, mining)

6. Intensive agriculture and aquacultural practices

7. Hybridization between native and non-native species and loss of native species

8. Natural disasters (Tsunami, forest fire, earthquake, volcanoes)

9. Industrialization, Urbanization, infrastructure development, Transport – Road and Shipping activity, communication towers, dam construction, unregulated tourism and monoculture

10. Co-extinction (loss of one species leading to extinction of another)

25. How can we contribute to promote biodiversity conservation?

Answer: We can contribute to biodiversity conservation through the following general strategies mentioned in the chapter: (1) Identify and protect all threatened species; (2) Identify and conserve in protected areas the wild relatives of all economically important organisms; (3) Identify and protect critical habitats for feeding, breeding, nursing and resting of each species; (4) Ensure air, water and soil are conserved on a priority basis; (5) Support the implementation of the Wildlife Protection Act; (6) Support in-situ conservation through national parks, wildlife sanctuaries and biosphere reserves; (7) Support ex-situ conservation through botanical gardens, zoological parks, wildlife safari parks and gene banks; (8) Spread awareness about the importance of biodiversity and the threats it faces so that communities and the younger generation volunteer to protect and conserve it for future generations.

26. Write a note on i) Protected areas   ii) Wild life sanctuaries

Answer:

i) Protected Areas: Protected areas are biogeographical areas where biological diversity along with natural and cultural resources is protected, maintained and managed through legal measures. They include national parks, wildlife sanctuaries, community reserves and biosphere reserves. World Conservation Monitoring Centre has recognized 37,000 protected areas worldwide. India has about 771 protected areas covering 162,099 km², comprising 104 National Parks, 544 Wildlife Sanctuaries, 18 Biosphere Reserves and several sacred groves. National parks are strictly reserved for betterment of wildlife and biodiversity where development, forestry, poaching, hunting, grazing and cultivation are not permitted. Biosphere Reserves are international designations by UNESCO for representative parts of natural and cultural landscapes. Sacred groves are groves of trees of special religious importance to particular cultures.

ii) Wild Life Sanctuaries: Any area other than reserve forest or territorial waters can be notified by the State Government to constitute as a sanctuary if it is of adequate ecological, faunal, floral, geomorphological, natural or zoological significance. They are meant for protecting endangered faunal species. Some restricted human activities are allowed inside sanctuary areas as per Chapter IV of the Wildlife Protection Act (WPA) 1972. Ecotourism is permitted as long as animal life is undisturbed. Other activities like collection of forest products, regulated harvesting of timber and private ownership of land are permitted. There are 544 existing wildlife sanctuaries in India covering an area of 118,918 km², which is 3.62% of the geographical area of the country. Periyar Wildlife Sanctuary in Kerala is famous for the Indian Tiger and Asiatic Elephant.

📝 Summary

1. Biodiversity, defined by the 1992 UN Earth Summit, refers to the variability among living organisms from all sources — terrestrial, marine, and aquatic — and includes diversity within species, between species, and across ecosystems; the term itself was introduced by Walter Rosen in 1986.
2. There are three levels of biodiversity — Genetic diversity, Species diversity, and Community or Ecosystem diversity — with genetic diversity covering variation within and between species, as seen in India's more than 50,000 genetic variants of Paddy and 1,000 variants of Mango.
3. The number of species per unit area declines as we move from the tropics towards the poles, with tropical forests of Panama having over 110 tree species, temperate forests of the United States having 20–35 species, and Tundra/Taiga regions possessing fewer than 12 species of trees.
4. Biodiversity plays essential roles in maintaining ecological processes such as soil creation, nutrient recycling, climate influence, waste degradation, and disease control, and serves as an index of ecosystem health upon which human survival depends.
5. Biodiversity faces serious threats from the ever-increasing human population, including hunting and poaching, which have driven species like the Nilgiris Thar to the IUCN Red List of threatened and endangered species.