Biodiversity And Conservation

Biodiversity

Biodiversity refers to the variety of life on Earth at all its levels, from genes to ecosystems, and the ecological and evolutionary processes that sustain it. It encompasses the diversity within species, between species, and of ecosystems.

Levels of Biodiversity:

• Genetic diversity: Variety of genes within a species. High genetic diversity allows a species to adapt to changing environments. Example: Genetic variations among different human populations, different varieties of rice or mango.
• Species diversity: Variety of species in a given area. Measured by species richness (number of species) and species evenness (relative abundance of individuals of each species).
• Ecological diversity: Variety of ecosystems in a region or on Earth. Example: Deserts, rainforests, grasslands, wetlands, estuaries, alpine meadows. Higher ecological diversity in a region often supports higher species diversity.

How Many Species Are There On Earth And How Many In India?

• According to the International Union for Conservation of Nature (IUCN, 2004), the total number of plant and animal species described so far is slightly more than 1.5 million.
• However, estimates of the total number of species on Earth vary widely. Some estimates range from 3 to 100 million species.
• A more conservative and scientifically sound estimate by Robert May places the global species diversity at about 7 million. This estimate is based on comparing the species-area relationship in tropical and temperate regions and extrapolating the richness of species in temperate regions to tropical regions.
• Among the known species, insects are the most species-rich group, followed by fungi, and then other groups.

Biodiversity in India:

• India is one of the 12 mega-diversity countries of the world.
• India has only 2.4% of the world's land area, but it accounts for 8.1% of the global species diversity.
• Based on Robert May's estimate, if the global species diversity is 7 million, then India's total species diversity might be over 100,000 plant species and over 300,000 animal species yet to be discovered and described.

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Patterns Of Biodiversity

Biodiversity is not uniformly distributed across the globe. It follows certain patterns:

• Latitudinal gradients: Species diversity generally decreases as we move from the equator towards the poles. Tropical regions (near the equator) have much higher species diversity than temperate or polar regions.
  • Reasons for higher diversity in tropics:
    • Tropics have remained undisturbed for millions of years, providing a longer time for species diversification.
    • Tropical environments are less seasonal and more stable, promoting niche specialisation.
    • Higher solar energy availability in tropics contributes to higher productivity, which can support a greater diversity of life.
• Species-Area relationship: The relationship between species richness and the area explored.
  • According to the German naturalist and geographer Alexander von Humboldt, within a region, species richness increases with increasing explored area, but only up to a certain limit.
  • The relationship is described by the equation: $ Log \: S = Log \: C + Z \: Log \: A $
    • S = Species richness
    • A = Area
    • Z = Slope of the line (regression coefficient)
    • C = Y-intercept
  • On a logarithmic scale, the relationship is a straight line: $ Log \: S $ versus $ Log \: A $.
  • The value of Z (slope) is typically between 0.1 and 0.2 for smaller areas (e.g., within a continent).
  • However, for very large areas (e.g., entire continents), the slope is steeper (Z value between 0.6 and 1.2). For frugivorous birds and mammals in tropical forests, Z is about 1.15.

  *(Image shows two graphs: one plotting Species Richness (S) vs Area (A) showing a curve approaching saturation, and another plotting Log S vs Log A showing a straight line with slope Z and Y-intercept Log C)*

The Importance Of Species Diversity To The Ecosystem

Species diversity plays a crucial role in maintaining the stability, productivity, and health of an ecosystem.

• Stability: Ecosystems with higher species diversity are generally more stable. A stable ecosystem shows little variation in productivity from year to year, is resistant to occasional disturbances (natural or man-made), and is resistant to invasion by alien species.
• Productivity: While not always a direct linear relationship, higher species diversity can contribute to higher and more stable productivity in an ecosystem. Different species utilise resources in different ways, leading to more efficient resource use.
• Ecosystem services: Biodiversity underpins many essential ecosystem services (provisioning, regulating, cultural, supporting) that are vital for human well-being. Loss of biodiversity can impair these services.
• Example (David Tilman's long-term ecosystem experiments): Plots with more species showed less year-to-year variation in total biomass and had higher total biomass.

Loss Of Biodiversity

Biodiversity is being lost at an alarming rate due to human activities. This loss is irreversible and has significant consequences for the planet and human society.

Causes of Biodiversity Loss (The 'Evil Quartet'):

• Habitat loss and fragmentation: The most important cause. Destruction of natural habitats (deforestation, urbanisation, pollution) directly leads to the extinction of species adapted to those habitats. Fragmentation of habitats breaks large continuous areas into smaller isolated patches, limiting species movement and genetic exchange, making them more vulnerable.
• Over-exploitation: Excessive harvesting or hunting of species for food, products, or trade can lead to population decline and extinction. Example: Overfishing, poaching of animals for fur, ivory, traditional medicine.
• Alien species invasions: Introduction of non-native (alien) species into a new geographical area. Some alien species can become invasive, outcompeting or predating upon native species, leading to their decline or extinction. Example: Introduction of Nile perch into Lake Victoria led to the extinction of over 200 species of cichlid fish. Introduction of *Parthenium* (carrot grass), *Lantana*, and *Eichhornia* (water hyacinth) in India have caused environmental damage.
• Co-extinctions: When a species becomes extinct, the species that is obligately associated with it (e.g., a parasite or a specific pollinator) also becomes extinct.

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Impacts of Biodiversity Loss:

• Loss of species, including potentially valuable species (e.g., for medicine, food).
• Disruption of ecosystem functions and services.
• Reduced stability and resilience of ecosystems.
• Increased vulnerability to environmental changes.

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The current rate of species extinction is estimated to be 100-1,000 times higher than the natural background extinction rate, primarily driven by human activities.

Biodiversity Conservation

Biodiversity conservation is the protection, preservation, management, and restoration of natural habitats and ecosystems, and the prevention of species extinction. Given the importance of biodiversity and the rapid rate of its loss, conservation has become a global priority.

Why Should We Conserve Biodiversity?

There are several compelling reasons to conserve biodiversity:

• Narrowly Utilitarian reasons: Direct economic benefits from biodiversity.
  • Food: Crops, livestock, fish, wild foods.
  • Medicines: Many drugs are derived from plants, animals, or microbes (e.g., more than 25% of drugs are derived from plants, over 25,000 species of plants contribute to traditional medicines in India).
  • Industrial products: Fibres, timber, rubber, resins, dyes.
  • Bioprospecting: Exploring molecular, genetic, and species-level diversity for products of economic importance.
• Broadly Utilitarian reasons: Indirect benefits from ecosystem services provided by biodiversity.
  • Oxygen production (by plants during photosynthesis).
  • Pollination of crops.
  • Climate regulation.
  • Water purification.
  • Soil formation and erosion control.
  • Flood and drought mitigation.
  • Aesthetic and recreational benefits (tourism, nature appreciation).
• Ethical reasons: Moral and ethical responsibility to protect other species and the diversity of life. The idea that all species have intrinsic value and the right to exist, regardless of their utility to humans. The responsibility to pass on the planet's biodiversity in good order to future generations.

How Do We Conserve Biodiversity?

Biodiversity conservation strategies involve protecting species and their habitats. There are two main approaches:

1. In situ Conservation (On-site conservation): Protecting entire ecosystems and the biodiversity within them in their natural habitats. This is the most effective approach for conserving the entire spectrum of biodiversity.
   • Biodiversity hotspots: Regions with high levels of species richness (endemism) and high threat of habitat loss. These are priority areas for conservation. Initially 25 hotspots were identified, now 36 globally. In India, there are three biodiversity hotspots: Western Ghats and Sri Lanka, Indo-Burma, and the Himalayas. These hotspots cover less than 2% of Earth's land area but contain very high species diversity.
   • Protected areas: Areas designated for the protection of wildlife and their habitats. Includes:
     • National Parks: Strictly protected, no human activity allowed.
     • Wildlife Sanctuaries: Protection of wildlife, some human activities (e.g., regulated tourism, collection of minor forest products) may be allowed.
     • Biosphere Reserves: Large protected areas with multiple zones (core, buffer, transition) designed for conservation, research, and sustainable human use.
   • Sacred Groves: Patches of forest conserved by local communities based on religious and cultural beliefs. These are found in India and other parts of the world and serve as important refuges for biodiversity. Example: Sacred groves in Meghalaya, Western Ghats, Aravalli Hills of Rajasthan.
2. Ex situ Conservation (Off-site conservation): Conserving biodiversity by protecting species outside their natural habitats, in artificial settings. Used particularly for endangered or threatened species.
   • Zoological Parks (Zoos): Captive breeding of animals.
   • Botanical Gardens: Conservation of plant species.
   • Wildlife Safaris/Parks: Rearing animals in protected areas, sometimes allowing restricted public access.
   • Gene banks/Seed banks: Storing genetic material (seeds, pollen, gametes, DNA) in viable condition for long periods (e.g., cryopreservation - preservation at very low temperatures).
   • In vitro fertilisation and tissue culture techniques: Used for propagating endangered species.

*(Image shows illustrations or symbols representing different conservation methods under in situ (e.g., forest with protected animals) and ex situ (e.g., zoo, botanical garden, seed bank))*

International Efforts for Conservation:

• The Earth Summit (Rio de Janeiro, 1992): Convention on Biological Diversity (CBD) was signed, calling for conservation of biodiversity, sustainable use of its components, and fair and equitable sharing of benefits from the utilisation of genetic resources.
• The World Summit on Sustainable Development (Johannesburg, 2002): Pledged to achieve a significant reduction in the current rate of biodiversity loss at the global, regional, and national levels by 2010. (Though the 2010 target was not met, it raised awareness).

Conservation of biodiversity is a complex task requiring global cooperation, national policies, local community involvement, and individual actions to reduce the pressure on natural ecosystems and prevent further species loss.