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Unit 3 - Notes

CHE110

Unit 3: Biodiversity and Conservation

1. Definition of Biodiversity

Biodiversity (Biological Diversity) refers to the variety and variability among living organisms from all sources, including terrestrial, marine, and other aquatic ecosystems and the ecological complexes of which they are part.

The term was popularized by sociobiologist E.O. Wilson in 1988. It encompasses the totality of genes, species, and ecosystems in a region.

2. Levels of Biological Diversity

Biodiversity is generally studied at three hierarchical levels:

A. Genetic Diversity

  • Definition: The variation of genes within a species.
  • Concept: It deals with the total number of genetic characteristics in the genetic makeup of a species.
  • Examples:
    • Rice: India has more than 50,000 genetically different strains of rice.
    • Mango: Over 1,000 varieties of mango are found in India.
    • Dogs: The distinct physical differences between a Chihuahua and a Great Dane are due to genetic diversity within the same species (Canis lupus familiaris).
  • Significance: Genetic diversity allows species to adapt to changing environments and resist diseases.

B. Species Diversity

  • Definition: The variety of species within a specific habitat or region.
  • Measurement Metrics:
    • Species Richness: The total count of different species in an area.
    • Species Evenness: The relative abundance of the different species (i.e., how evenly the individuals are distributed among the different species).
  • Example: The Western Ghats have a higher amphibian species diversity compared to the Eastern Ghats.

C. Ecosystem Diversity

  • Definition: The variety of ecosystems (habitats, biological communities, and ecological processes) in the biosphere.
  • Concept: It includes differences in habitat types and the diversity of processes (energy flow and nutrient cycling) occurring within them.
  • Examples: Forests, grasslands, deserts, mountains, aquatic ecosystems (wetlands, coral reefs, mangroves).
  • Scale: India exhibits high ecosystem diversity, ranging from the cold deserts of Ladakh to the tropical rainforests of Kerala and the coral reefs of Lakshadweep.

3. Importance of Biodiversity

A. Ecosystem Services (Functional Value)

Biodiversity provides critical services that sustain life on Earth:

  1. Provisioning Services: Direct products obtained from ecosystems (food, fresh water, wood, fiber, genetic resources).
  2. Regulating Services: Benefits obtained from the regulation of ecosystem processes (climate regulation, flood control, disease regulation, water purification).
  3. Supporting Services: Services necessary for the production of all other ecosystem services (soil formation, nutrient cycling, primary production).

B. Ecological Value

  • Interdependence: Species are linked via food webs. The extinction of a keystone species (e.g., bees for pollination, tigers for population control of herbivores) can cause ecosystem collapse.
  • Resilience: High biodiversity makes ecosystems more resilient to disturbances (storms, fires, climate change).

C. Economic Value

  • Direct Use Value:
    • Food: Cereal crops, livestock, fish.
    • Medicine: 25% of all prescription drugs are derived from rainforest plants (e.g., Quinine for malaria from Cinchona tree; Taxol for cancer from Yew tree).
    • Industry: Rubber, timber, oils, tannins, dyes.
  • Productive Use Value: Commercial products harvested for markets.

D. Social and Cultural Value

  • Indigenous communities often live in harmony with nature, depending on local biodiversity for their livelihood and cultural identity.
  • Sacred Groves: Patches of forests protected by local communities due to religious beliefs (e.g., Devrais in Maharashtra, Khasi Hills in Meghalaya).

E. Aesthetic Value

  • Biodiversity contributes to the beauty of the landscape.
  • It supports Ecotourism (bird watching, wildlife safaris), which generates significant revenue and promotes mental well-being.

F. Informational/Option Value

  • Option Value: The potential of biodiversity to provide benefits in the future (e.g., a cure for HIV or cancer may exist in a plant species not yet studied).
  • Scientific Value: Understanding the evolution of life and ecological processes.

4. Biogeographic Zones of India

India is divided into 10 Biogeographic Zones based on geography, climate, and species patterns (Classification by Rodgers & Panwar):

  1. Trans-Himalaya: Cold deserts of Ladakh and Lahaul-Spiti; fauna includes Snow Leopard, Yak.
  2. Himalaya: Northwest, West, Central, and East Himalayas; timberline vegetation; fauna includes Musk Deer, Red Panda.
  3. Desert: Thar desert (Rajasthan) and Kutch; fauna includes Great Indian Bustard, Wild Ass.
  4. Semi-Arid: Transition zone between desert and dense forests; thorny scrub; fauna includes Blackbuck, Gir Lion.
  5. Western Ghats: High rainfall, tropical evergreen forests; high endemism; fauna includes Lion-tailed Macaque, Malabar Giant Squirrel.
  6. Deccan Peninsula: Largest zone (Plateau); deciduous forests; fauna includes Tiger, Sloth Bear.
  7. Gangetic Plain: Fertile alluvial soil; intensive agriculture; fauna includes Gangetic Dolphin, Rhinoceros (in Terai).
  8. Coasts: Mangroves and sandy beaches; fauna includes Dugong, Olive Ridley Turtle.
  9. North-East: Tropical rainforests; biodiversity gateway; fauna includes Hoolock Gibbon, One-horned Rhino.
  10. Islands: Andaman & Nicobar, Lakshadweep; high endemism; fauna includes Narcondam Hornbill, Saltwater Crocodile.

India as a Mega Diversity Nation

  • India is one of the 17 Mega-diverse countries in the world.
  • Land Area: 2.4% of the world’s land area.
  • Species Share: Accounts for 7–8% of the global recorded species.
  • Plant Diversity: Over 45,000 plant species (7% of world total).
  • Animal Diversity: Over 91,000 animal species (6.5% of world total).
  • Endemism: High percentage of species found nowhere else (especially in Western Ghats and Eastern Himalayas).

5. Biodiversity Hotspots

A Biodiversity Hotspot is a region with high levels of species richness and high degrees of endemism that is under significant threat.

Criteria (Norman Myers):

  1. Must contain at least 1,500 species of vascular plants (> 0.5% of the world’s total) as endemics.
  2. Must have lost at least 70% of its original habitat.

Hotspots in India:
India hosts 4 out of the 36 global biodiversity hotspots:

  1. The Himalayas: Includes the entire Indian Himalayan region (and parts of Pakistan, Tibet, Nepal, Bhutan, China, Myanmar).
  2. Indo-Burma: Includes entire North-eastern India (except Assam and Andaman group of Islands).
  3. The Western Ghats and Sri Lanka: Includes the entire Western Ghats.
  4. Sundaland: Includes Nicobar group of Islands (and Indonesia, Malaysia).

6. Threats to Biodiversity (The "HIPPO" Acronym)

A. Habitat Loss and Fragmentation (Primary Threat)

  • Causes: Deforestation for agriculture, urbanization, mining, and dam construction.
  • Fragmentation: Large habitats are broken into smaller patches, isolating populations, reducing genetic exchange, and creating "edge effects."

B. Poaching of Wildlife

  • Commercial Poaching: Illegal trade in animal parts (Tiger bones/skin for TCM, Rhino horn, Elephant ivory, Pangolin scales).
  • Subsistence Poaching: Hunting for food (bushmeat).

C. Biological Invasions (Invasive Alien Species)

  • Introduction of non-native species that reproduce rapidly and outcompete native species for resources.
  • Examples:
    • Lantana camara (Plant): Overtakes forest undergrowth, unpalatable to herbivores.
    • Eichhornia crassipes (Water Hyacinth): Clogs water bodies, kills aquatic life.
    • African Catfish: Threatens indigenous fish varieties.

D. Human-Wildlife Conflicts

  • Occurs when human requirements encroach on wildlife habitats.
  • Scenarios:
    • Elephants raiding crops in South/East India.
    • Leopards entering urban areas (Mumbai, Guwahati) preying on dogs/livestock.
  • Consequences: Loss of crops/livestock, human injury/death, and retaliatory killing of animals.

7. Species of Conservation Concern

The IUCN (International Union for Conservation of Nature) Red List categories:

A. Extinct Species (EX)

  • Species about which there is no reasonable doubt that the last individual has died.
  • Examples: Dodo (Mauritius), Passenger Pigeon, Pink-headed Duck (India).

B. Endangered Species (EN)

  • Species facing a very high risk of extinction in the wild in the near future.
  • Examples: Bengal Tiger, Asian Elephant, Asiatic Lion, Blue Whale.

C. Vulnerable Species (VU)

  • Species facing a high risk of extinction in the wild. If threats continue, they will become endangered.
  • Examples: One-horned Rhinoceros, Snow Leopard, Olive Ridley Turtle.

D. Rare Species

  • Species with naturally small populations, either localized within a restricted geographical area or thinly scattered over a more extensive range. They are not necessarily threatened but are at risk.
  • Example: Himalayan Musk Deer, Great Pied Hornbill.

E. EDGE Species (Evolutionarily Distinct and Globally Endangered)

  • Species that have few close relatives on the tree of life (Evolutionarily Distinct) and are facing a high risk of extinction (Globally Endangered).
  • Conservation of these species is crucial to preserving unique evolutionary history.
  • Examples:
    • Purple Frog (Nasikabatrachus sahyadrensis): Found in Western Ghats.
    • Ganges River Dolphin.
    • Chinese Pangolin.

8. Conservation of Biodiversity

A. In-situ Conservation (On-site)

Protecting species within their natural habitats. This allows evolution to continue naturally.

  1. National Parks:
    • Strictly protected areas.
    • No human activity allowed (no grazing, forestry, or private ownership).
    • Examples: Jim Corbett NP (Uttarakhand), Kaziranga NP (Assam).
  2. Wildlife Sanctuaries:
    • Protected areas oriented toward species conservation.
    • Limited human activity allowed (harvesting timber, collecting minor forest products) if it doesn't interfere with wildlife.
    • Examples: Periyar WS (Kerala), Bharatpur Bird Sanctuary (Rajasthan).
  3. Biosphere Reserves:
    • Large areas integrating conservation with sustainable development.
    • Zones:
      • Core Zone: Strictly protected (Legal status of National Park).
      • Buffer Zone: Research and education allowed.
      • Transition Zone: Human settlements and sustainable usage allowed.
    • Examples: Nilgiri Biosphere Reserve, Sundarbans, Nanda Devi.
  4. Sacred Groves:
    • Community-protected forest fragments.

B. Ex-situ Conservation (Off-site)

Protecting species outside their natural habitats (artificial conditions).

  1. Zoological Parks & Aquariums: Breeding of endangered animals (e.g., Captive breeding of Pygmy Hog).
  2. Botanical Gardens: Conservation of rare plant species (e.g., Indian Botanical Garden, Kolkata).
  3. Gene Banks / Seed Banks:
    • Storage of seeds at low temperatures.
    • Svalbard Global Seed Vault (Norway).
  4. Cryopreservation: Storing gametes, embryos, or DNA in liquid nitrogen (-196°C).
  5. Tissue Culture: Propagating plants from cells in a sterile environment (Micro-propagation).