Detailed Notes – 2 -CHAPTER 13 BIODIVERSITY AND CONSERVATION

13.1.3 The importance of Species Diversity to the Ecosystem

• Stability and Species Diversity

  • Stability of a biological community refers to its ability to maintain consistent productivity, resist disturbances, and prevent invasion by alien species.
  • Historically, ecologists believed that communities with higher species richness tended to be more stable.

• David Tilman’s Experiments

  • Tilman’s long-term ecosystem experiments using outdoor plots suggested that plots with more species showed less year-to-year variation in total biomass.
  • Increased diversity contributed to higher productivity in his experiments.

• Understanding Ecosystem Well-being

  • While the exact mechanisms linking species richness to ecosystem well-being are not fully understood, it’s recognized that rich biodiversity is crucial for ecosystem health.
  • Biodiversity is imperative for the survival of the human race on Earth.

• Impact of Species Loss

  • Questions arise about the significance of species loss: Does it matter if a few species become extinct?
  • Analogy: Paul Ehrlich’s “rivet popper hypothesis” likens species in an ecosystem to rivets in an airplane. Each species plays a role in maintaining ecosystem function, and their loss can weaken the ecosystem over time.
  • Loss of key species (like rivets on wings) can have a more severe impact on ecosystem functions and stability.

• Perspective and Conservation

  • Conservation efforts are crucial to prevent further species loss and maintain ecosystem functionality.
  • While it may not be immediately obvious how each species contributes, the interconnectedness and complexity of ecosystems highlight the importance of preserving biodiversity.

13.1.4 Loss of Biodiversity

• Extent of Biodiversity Loss

  • Extinction rate: Species are being lost at an alarming rate due to human activities.
  • Extinction examples: Extinct species include the dodo, quagga, thylacine, and subspecies of tigers.
  • Vulnerability of taxa: Some groups like amphibians are more vulnerable to extinction.

• Current Threats to Biodiversity

  • Extinction threats: Over 15,500 species worldwide are facing the threat of extinction.
  • Percentages: A significant proportion of bird, mammal, amphibian, and gymnosperm species are at risk.

• Comparison with Past Extinctions

  • Historical extinctions: Mass extinctions occurred before humans, but current rates are 100 to 1,000 times faster.
  • Human impact: Human activities are responsible for accelerated extinction rates.

• Causes of Biodiversity Loss (“The Evil Quartet”)

  • Habitat loss and fragmentation: Most critical cause, especially in tropical rainforests.
  • Over-exploitation: Overharvesting of resources leading to species decline.
  • Alien species invasions: Introduction of invasive species causing declines or extinctions of native species.
  • Co-extinctions: Extinction of species leads to associated species’ extinctions (e.g., host-parasite relationships).

• Impact of Biodiversity Loss

  • Decline in ecosystem services: Loss of plant production, reduced resistance to environmental changes like drought, increased variability in ecosystem processes.
  • Fragmentation effects: Disruption of habitats affects populations of mammals, birds, and migratory species.

13.2 BIODIVERSITY CONSERVATION

13.2.1 Why Should We Conserve Biodiversity?

1. Narrowly Utilitarian Reasons

   • Direct economic benefits: Humans derive various economic benefits from nature such as food, firewood, fiber, construction materials, and industrial products (like tannins, lubricants, dyes, resins, and perfumes).
   • Medicinal importance: Over 25% of drugs in the market are derived from plants, and traditional medicines use thousands of plant species. Bioprospecting in biodiverse regions can lead to significant discoveries in medicine and industry.

2. Broadly Utilitarian Reasons

   • Ecosystem services: Biodiversity plays a crucial role in ecosystem services like oxygen production through photosynthesis. For example, the Amazon rainforest alone produces around 20% of Earth’s oxygen.
   • Pollination: Natural pollinators like bees, birds, and bats provide essential pollination services, which are vital for food production.
   • Aesthetic and intangible benefits: Nature provides aesthetic pleasures such as enjoying natural landscapes, observing wildlife, and experiencing the beauty of biodiversity. These intangible benefits contribute to human well-being.

3. Ethical Reasons

   • Intrinsic value: Every species has intrinsic value, irrespective of its economic importance to humans. Each species contributes to the overall balance and functioning of ecosystems.
   • Moral duty: Humans have a moral responsibility to care for the well-being of all species and to preserve biodiversity for future generations.
   • Biological legacy: Conserving biodiversity ensures that we pass on a diverse and healthy natural world to future generations, maintaining the richness and complexity of life on Earth.

13.2.2 How do we conserve Biodiversity? 

1. In Situ Conservation:

   • Biodiversity Hotspots: Identified regions with high species richness and endemism. Protecting these areas can significantly reduce extinctions.
   • Conservation Areas: Establishing biosphere reserves, national parks, and wildlife sanctuaries to protect ecologically unique and biodiverse regions.
   • Traditional Practices: Emphasizing protection through religious and cultural traditions, such as sacred groves, where nature is venerated and given total protection.
   • Legal Protections: Implementing laws and regulations to safeguard natural habitats and species within designated protected areas.

2. Ex Situ Conservation:

   • Zoological Parks and Botanical Gardens: Providing a controlled environment for threatened animals and plants outside their natural habitats.
   • Cryopreservation: Preserving gametes (sperm and eggs) of threatened species in viable conditions for long periods using cryopreservation techniques.
   • In Vitro Fertilization: Fertilizing eggs of threatened species in vitro to maintain genetic diversity and prevent extinction.
   • Tissue Culture: Propagating plants through tissue culture methods to preserve genetic diversity and rare plant species.
   • Seed Banks: Storing seeds of different genetic strains of commercially important plants for long-term conservation and future use.

3. Global Conservation Efforts:

   • Convention on Biological Diversity (CBD): International agreement calling upon nations to take measures for biodiversity conservation and sustainable utilization of its benefits.
   • World Summit Commitments: Pledges made by countries to achieve a significant reduction in the rate of biodiversity loss by promoting conservation efforts globally, regionally, and locally.