Biodiversity and Conservation

2.1 Core concepts

• Linkage with earlier chapter: NCERT opens by linking back to weathering and the depth of weathering mantle (Fig. 5.2 in Ch. 5), pointing out that the weathering mantle is the basis for the diversity of vegetation and hence biodiversity, and that the underlying drivers of weathering variations and resultant biodiversity are the inputs of solar energy and water — areas rich in these inputs host the widest spectrum of biodiversity (NCERT §Introduction, p. 115).
• What is biodiversity? Biodiversity is the number and variety of organisms found within a specified geographic region; it refers to the variability among living organisms on the earth, including variability within and between species and between ecosystems. The term combines Bio (life) and diversity (variety). It is our "living wealth" — the result of hundreds of millions of years of evolutionary history (NCERT §Introduction, p. 115).
• Evolutionary timeline (Box, p. 115). Biodiversity as we have today is the result of 2.5–3.5 billion years of evolution. Before the advent of humans, Earth supported more biodiversity than in any other period; since the emergence of humans, biodiversity has been in rapid decline due to overuse. The number of species globally is estimated at between 2 million and 100 million, with 10 million being the best estimate. New species are regularly discovered, most yet to be classified — about 40% of fresh water fishes from South America are still unclassified. Tropical forests are very rich in bio-diversity.
• Average species half-life. The average half-life of a species is estimated at between one and four million years, and 99 per cent of all species that have ever lived on Earth are today extinct (NCERT p. 115).
• Biodiversity is richer in the tropics. Biodiversity is not evenly distributed; it is consistently richer in the tropics. As one approaches the polar regions, one finds larger and larger populations of fewer and fewer species — the classic latitudinal diversity gradient (NCERT p. 115).
• Three levels of biodiversity: (i) Genetic diversity — variation of genes within species; (ii) Species diversity — variety of species in a defined area, measured through richness, abundance and types; (iii) Ecosystem diversity — broad differences between ecosystem types and the diversity of habitats and ecological processes within them (NCERT pp. 115–116).
• Genetic diversity. Genes are the basic building blocks of various life forms. Groups of individual organisms having certain similarities in physical characteristics are called species. Human beings genetically belong to the homo sapiens group and differ considerably in height, colour, physical appearance, etc., due to genetic diversity. Genetic diversity is essential for a healthy breeding of population (NCERT p. 115).
• Species diversity. Variety of species — number in a defined area, measured through richness, abundance and types; some areas are richer than others; areas rich in species diversity are called hotspots of diversity (NCERT p. 116, Fig. 14.5).
• Ecosystem diversity. Broad differences between ecosystem types and the diversity of habitats and ecological processes; "boundaries" of communities and ecosystems are not rigidly defined, so demarcation is difficult and complex (NCERT p. 116).
• Ecological role of biodiversity. Species perform functions in an ecosystem — capturing and storing energy, producing and decomposing organic materials, cycling water and nutrients, fixing atmospheric gases, and helping regulate climate. A more diverse ecosystem has better chances for species to survive adversities and is more productive; an ecosystem with high biodiversity has a greater chance of adapting to environmental change — "the more the variety of species in an ecosystem, the more stable the ecosystem is likely to be" (NCERT p. 116).
• Economic role of biodiversity. Important economic commodities supplied by biodiversity include food crops, livestock, forests, fish and medicinal resources. Crop diversity (agro-biodiversity) is one important economic aspect. Biodiversity is a reservoir of resources for food, pharmaceuticals and cosmetic products. The concept of biological resources is also a source of conflict over rules of division and appropriation of natural resources (NCERT p. 116).
• Scientific role of biodiversity. Each species gives clues as to how life evolved and continues to evolve; biodiversity helps in understanding how life functions and the role of each species in sustaining ecosystems (NCERT pp. 116–117).
• Ethical role. It is our ethical responsibility to consider that each species along with us has an intrinsic right to exist — it is morally wrong to voluntarily cause the extinction of any species; the level of biodiversity is a good indicator of the state of our relationships with other living species; the concept of biodiversity is an integral part of many human cultures (NCERT p. 117).
• Loss of biodiversity — human causes. Growth of human population has increased the rate of consumption of natural resources and accelerated the loss of species and habitats. Tropical regions occupy only about one-fourth of the total area of the world but contain about three-fourths of the world human population; tropical rain forests contain 50 per cent of the species on Earth, so the destruction of natural habitats has been disastrous for the biosphere (NCERT §Loss of Biodiversity, p. 117).
• Natural calamities and pollutants. Earthquakes, floods, volcanic eruptions, forest fires and droughts cause damage to the flora and fauna; pesticides, hydrocarbons and toxic heavy metals destroy weak and sensitive species.
• Exotic species. Species that are not natural inhabitants of a local habitat but are introduced into the system are called exotic species. Many natural biotic communities have suffered extensive damage from such introductions (NCERT p. 117).
• Poaching. In the last few decades animals such as tigers, elephants, rhinoceros, crocodiles, minks and birds have been hunted mercilessly by poachers for their horn, tusks, hides etc., rendering certain organisms endangered (NCERT p. 117).
• IUCN categories of threatened species (p. 117). The International Union of Conservation of Nature and Natural Resources (IUCN) classifies threatened species into three categories:
• (i) Endangered Species — in danger of extinction; published in the Red List of threatened species.
• (ii) Vulnerable Species — likely to be in danger of extinction in the near future if threatening factors continue; survival not assured as population has reduced greatly.
• (iii) Rare Species — very small population in the world; confined to limited areas or thinly scattered over a wider area.
• Conservation of biodiversity. All life forms are closely interlinked; disturbance in one causes imbalance in others. If species of plants and animals become endangered, they cause degradation in the environment, which may threaten human existence itself (NCERT §Conservation, p. 117).
• Earth Summit 1992. The Government of India along with 155 other nations signed the Convention of Biodiversity at the Earth Summit held at Rio de Janeiro, Brazil in June 1992 (NCERT p. 118).
• World Conservation Strategy — six steps for biodiversity conservation (NCERT p. 118):
• (i) Efforts should be made to preserve the species that are endangered.
• (ii) Prevention of extinction requires proper planning and management.
• (iii) Varieties of food crops, forage plants, timber trees, livestock, animals and their wild relatives should be preserved.
• (iv) Each country should identify habitats of wild relatives and ensure their protection.
• (v) Habitats where species feed, breed, rest and nurse their young should be safeguarded.
• (vi) International trade in wild plants and animals should be regulated.
• Wild Life (Protection) Act, 1972. To protect, preserve and propagate the variety of species within natural boundaries, the Government of India passed this Act, under which national parks and sanctuaries were established and biosphere reserves declared (NCERT p. 118).
• Mega diversity centres (p. 118). Countries situated in tropical regions possessing a large number of the world's species diversity are called mega diversity centres. There are 12 such countries: Mexico, Colombia, Ecuador, Peru, Brazil, Democratic Republic of Congo, Madagascar, China, India, Malaysia, Indonesia and Australia.
• Biodiversity hotspots. The IUCN has identified certain areas as biodiversity hotspots. Hotspots are defined according to their vegetation — plants are important because they determine the primary productivity of an ecosystem. Most (but not all) hotspots rely on species-rich ecosystems for food, firewood, cropland and income from timber. In Madagascar, about 85 per cent of the plants and animals are found nowhere else in the world; the islands of Hawaii have many unique plants and animals threatened by introduced species and land development (NCERT p. 118).
• Hotspots mapped in Figure 14.4 (p. 119) include the Eastern Himalaya, Western Ghats (India), Sinharaja Forest (Sri Lanka), Eastern Madagascar, Eastern Arc Mountains (Tanzania), Upper Guinean Forests, Central American Highland Forests, Central American Lowland Forests, Western Ecuador and Colombian Choco, Tropical Andes, Atlantic Forest (Brazil), Peninsular Malaysia, Philippines, Northern Borneo, Sinharaja Forest, Indonesia, Queensland, and Melanesia (New Caledonia).
• Sustainable use through community participation. Conservation with sustainable use is possible only with the involvement and cooperation of local communities and individuals; development of institutional structures at local levels is necessary; the critical problem is "the continuation of the process of conservation" — not merely species or habitat conservation in a one-off way (NCERT p. 118).

2.2 Definitions to memorise

2.3 Diagrams / processes to remember

• Figure 14.1 (p. 116): Grasslands and sholas in Indira Gandhi National Park, Annamalai, Western Ghats — illustrates ecosystem diversity with mixed habitat types in the same landscape.
• Figure 14.2 (p. 117): Red Panda — example of an endangered species in the IUCN Red List; memorise as the flag species for "Endangered".
• Figure 14.3 (p. 118): Humbodtia decurrens Bedd — highly rare endemic tree of the Southern Western Ghats (India); illustrates the concept of rare/endemic species and why specific geographic regions are hotspots.
• Figure 14.4 (p. 119) — Map of some ecological hotspots in the world: Eastern Himalaya, Western Ghats, Sinharaja Forest (Sri Lanka), Eastern Madagascar, Eastern Arc Mountains (Tanzania), Upper Guinean Forests, Central American Lowland/Highland Forests, Western Ecuador and Colombian Choco, Tropical Andes, Atlantic Forest (Brazil), Peninsular Malaysia, Philippines, Northern Borneo, Indonesia, Queensland, Melanesia (New Caledonia).
• Biodiversity distribution gradient (conceptual, p. 115): Biodiversity consistently increases from poles to tropics — standard latitudinal diversity gradient.
• Process flow — Loss → IUCN classification → Conservation: Anthropogenic + natural causes → loss of species → IUCN classifies into Endangered/Vulnerable/Rare → publishes Red List → world conservation strategy (Rio 1992) → national-level Wild Life (Protection) Act 1972 → national parks, sanctuaries, biosphere reserves.

2.5 Key data table (chapter facts at a glance)

2.4 Common confusions / NTA trap points

• Endangered vs. Vulnerable vs. Rare — students often conflate these three IUCN categories. Endangered = in danger NOW; Vulnerable = likely to be endangered if threats continue; Rare = small/scattered population but not immediately threatened. NTA frequently offers all three as options in a single stem.
• Hotspot vs. Mega-diversity centre — a hotspot is a geographic area identified by IUCN based on vegetation/plant diversity and threat level; a mega-diversity centre is a country in the tropics with large species numbers. India is BOTH.
• Number of mega-diversity countries — NCERT gives 12. NTA may offer 10, 12, 14, or 17 as options (17 is a later update not in the NCERT). Stick to 12.
• Wild Life (Protection) Act year — 1972, not 1970 or 1975.
• Earth Summit location — Rio de Janeiro, Brazil, June 1992 — not Stockholm (1972 Stockholm Conference on Human Environment is a different event); NTA regularly tests both years and cities together.
• Hotspots defined by vegetation, not by animals — NCERT explicitly says "plants are important because they determine the primary productivity of an ecosystem".
• 99% of species that ever lived are extinct, not 9% or 90% — a common stem.
• Tropical regions = ~1/4 of land but ~3/4 of human population AND 50% of species in tropical rain forests — three different ratios; CUET swaps them.
• Best estimate of global species count = 10 million (within a 2-100 million range); the range and the point estimate are different.
• Red List is published by IUCN, not by WWF or UN.
• Genetic diversity ≠ species diversity ≠ ecosystem diversity — the strict hierarchy is "within species / between species / between ecosystems".