Chapter 13 Solutions — Biodiversity and Conservation

Biodiversity, as described by Edward Wilson, encompasses diversity at all levels of biological organisation. The three most important components are:

1. Genetic diversity: Diversity within a species at the genetic level. For example, India has more than 50,000 genetically different strains of rice and 1,000 varieties of mango. The medicinal plant Rauwolfia vomitoria shows variation in the potency and concentration of the active chemical reserpine across different Himalayan ranges.

2. Species diversity: Diversity at the species level — the variety of species in a region. For example, the Western Ghats have greater amphibian species diversity than the Eastern Ghats.

3. Ecological (ecosystem) diversity: Diversity at the ecosystem level. India, with its deserts, rain forests, mangroves, coral reefs, wetlands, estuaries and alpine meadows, has far greater ecosystem diversity than a Scandinavian country like Norway.

Estimating the total number of species on Earth is a major challenge because a vast number of species are yet to be discovered and described. Ecologists use the following approach:

Species inventories are far more complete for temperate regions than for tropical regions. Biologists take an exhaustively studied group of insects (or another taxonomic group) and compare the ratio of temperate species to tropical species for that group. They then extrapolate this temperate-to-tropical ratio to other groups of animals and plants to arrive at a gross estimate of total species on Earth.

Using this statistical extrapolation, Robert May placed the global species diversity at about 7 million, though some extreme estimates range from 20 to 50 million. Currently, about 1.5 million species have been formally described (per IUCN 2004).

The estimates are uncertain because: (a) tropical regions are under-explored, (b) microbial/prokaryotic species are difficult to identify using conventional taxonomic methods, and (c) many species face extinction before they can be discovered and named.

Sacred groves are tracts of forest set aside by local communities for religious and cultural reasons. All the trees and wildlife within these tracts are venerated and given total protection by the community — no cutting, hunting, or disturbance is permitted.

In India, sacred groves are found in:

— Khasi and Jaintia Hills in Meghalaya

— Aravalli Hills of Rajasthan

— Western Ghats regions of Karnataka and Maharashtra

— Sarguja, Chanda and Bastar areas of Madhya Pradesh

Role in conservation:

Sacred groves serve as important refuges for rare and threatened plant and animal species. In Meghalaya, for example, the sacred groves are the last refuges for a large number of rare and threatened plants that may have disappeared from the surrounding degraded landscape. They help preserve local biodiversity, protect watersheds and forest patches, and often conserve species not found anywhere else in the vicinity. They represent an indigenous, community-based in situ conservation strategy that has existed for centuries.