Complete information on Biodiversity at Global, National and Local Levels

Biodiversity is the measure of the variety of earth’s animal, plant and microbial species; of genetic differences within species; and of the ecosystems that support the species. Out of an estimated 30 million species on earth, only one-sixth has been identified and authenticated in the past 200 years. An estimated biodiversity covers 400,000 higher plants. Other species are given in Table 10.1.

Between seven and nine million square kilometres of tropical rain forests, covering large tracts of Central America, the Amazon basin and the Guianas, West Africa and Zaire, South East Asia, New Guinea and the islands of Melanesia are estimated to be there on the face of the earth.

In Central America, two-thirds of the forests have already disappeared. In Columbia, it has been cleared at the rate of a million hectares a year. The tragic story of the rain forests in Brazil is no different. Tropical rain forests are the greatest, most enduring celebrations of life ever to have evolved on this planet. No other environment has so many species of plant and animal life.

Biologically, tropical rain forests are the centres of the world; much of the earth’s contemporary flora and fauna originated in the humid tropics. For millions of years, tropical rain forests have been factories of evolutionary diversity from which plants and animals, capable of adapting to more difficult environments, have gone forth to populate the subtropical and temperate regions.

It is essential to maintain areas of tropical rain forest large enough for this evolution to continue.

(Source: Botanical Survey of India, Kolkata)

The tropical forests are regarded as the richest in biodiversity. Species diversity in tropics is high. The reasons are as follows:

1. Warm temperate and high humidity provide favourable conditions for many species.

2. Tropical communities are more productive because these areas receive more solar energy.

3. Over geographical times the tropics have had a more stable climate. In tropics, therefore, local species continued to live there itself.

4. Among plant rates of out crossing appear to be higher in tropics.

Biodiversity exists on earth in eight broad realms with 193 biogeographical provinces. Each biogeographical province is composed of ecosystems, which are constituted by communities of living species existing in an ecological region.

The developing countries, located in subtropical/ tropical belt are far richer in biodiversity than the industrial countries in the temperate region. The Valvilovian Centres of diversity of crops and domesticated animals are also located in the developing countries.