Biodiversity (or biological diversity) has been described as the rich variety of life on Earth. So far, mankind has discovered about 1.75 million living things; estimates of the total number of species on Earth range from 5 million to 100 million species. Biodiversity is critical to every person on this planet. All of nature's plants and animals contribute to maintaining a healthy place for us to live. We depend on them for food, air, water, clothing, building materials, medicines, and natural refuges.
Nature is healthiest and strongest when there is a rich variety of different species, with an abundance of genetic diversity within species. Living organisms interact with one another, and delicate balances between and among organisms are achieved through millions of intricate, natural processes. These balances are easily impaired or destroyed.
Our world's natural biodiversity is in trouble. Planet Earth is undergoing a rapid loss of species, causing ecological crises on a global scale. Scientists around the world are warning us that we are destroying, at an unprecedented rate in human history, the very things that give us life and good health.
Human activities are largely responsible for the rapid loss of species. Examples include clear-cut logging, road building, conversion of natural lands to single-species crops, over-fishing, draining wetlands, burning rainforests and damming watersheds. These types of activities destroy or change natural habitats and populations to the point where local plants and animals cannot cope, populations dwindle, and often species begin to disappear. Losses may be more serious than we know because there are many undiscovered species and many unknown interactions between species. This realization should intensify our concern for the life-giving values we may be destroying.
HOT SPOTS – AN INTRODUCTION
Biodiversity is not distributed uniformly across the globe. Some habitats, particularly tropical forests among terrestrial systems possess a greater number or density of species than others. Thus a 13.7 sq km area of the La Selva Forest Reserve in Costa Rica contains almost 1,500 plant species, more than the total found in 243,500 sq km of Great Britain, while Ecuador harbours more than 1,300 bird species, or almost twice as many as the USA and Canada combined (Myers, 1988). It is widely accepted that the identification and prioritisation of important centres of biodiversity are necessary at both the national and the global scale for conservation action. A number of methods by which such areas could be determined have been suggested.
The most widely accepted approach of suggesting target areas for conservation action is to identify areas with the greatest number of endemic or restricted-range species. An endemic species is one restricted to some given area, which might be a mountain top, a river, a country or continent.
An important study that has attempted to use endemic species to identify areas of global conservation concern was that of Myers (1988, 1990). Focusing on tropical forests, Myers identified 18 regions or ‘hot spots’ that are characterised by high concentration of endemic species and are experiencing unusually rapid rates of habitat modification or loss. Together, these 18 sites contain approximately 49,955 endemic plant species, or 20% of the world’s recorded plant species, in only 746,400 sq km or 0.5% of the earth's land surface.
INDIA—A MEGA BIODIVERSITY COUNTRY
India is one of the 12 mega biodiversity countries of the world. The country is divided into 10 bio-geographic regions : Trans-Himalayan, Himalayan, Indian Desert, Semi-Arid, Western Ghats, Deccan Peninsula, Gangetic Plains, North-East India, Islands and Coasts, and this diversity creates rich biodiversity in the country. The wide variety in physical features and climatic situations have resulted in a diversity of ecological habitats like forests, grasslands, wetlands, coastal and marine ecosystems and desert ecosystems, which harbour and sustain the immense biodiversity. With only 2.4% of the total land area of the world, the known biological diversity of India contributes 8% to the known global biological diversity. Currently available data place India in the tenth position in the world and fourth in Asia in plant diversity. In terms of the number of mammalian species, India ranks tenth in the world; in terms of the endemic species of higher vertebrates, it ranks eleventh. It stands seventh in the world for the number of species contributed to agriculture and animal husbandry.
CONSERVATION OF BIODIVERSITY IN INDIA
Conservation and sustainable use of biological resources based on local knowledge systems and practices is ingrained in Indian ethos and way of life. Initiation of policies and programmes for conservation and sustainable utilisation of biological resources date back to several decades. As a result, India has a strong network of institutions mapping biodiversity and undertaking taxonomic studies. The Botanical Survey of India (established in 1890) and the Zoological Survey of India (established in 1916) are primarily responsible for survey of flora and fauna. The National Institute of Oceanography and several other specialised institutions and universities further strengthen the taxonomic data base. Based on the survey of 70% of the total geographical area of the country, 46,000 species of plants and 81,000 species of animals have been recorded so far. These life forms are actually and potentially important for developments in the fields of food, medicine, textiles, energy, recreation and tourism. The areas not yet surveyed include the inaccessible Himalayan area, Andaman and Nicobar Islands and Exclusive Economic Zone. These areas are expected to be rich repositories of endemic and other species.
तेवरी का सौन्दर्य-बोध / रमेशराज
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