Summary

The Biodiversity Conservation Act 1999 emphasizes the conservation of biodiversity rich areas and their sustainable use especially, in the developing countries. And for a country like India which is diverse with all variety of flora and fauna,   conservation of natural wealth becomes a priority in the urban sprawl. The International Convention on Biological Diversity 1992 obliges all parties, including India to prepare an inventory and monitor biodiversity and make all attempts to conserve these resources. This enormous task is not possible only by ground survey and research. The Global Biodiversity Assessment (UNEP, 1995) recommends that such assessment   requires a detailed knowledge of species distribution in particular landscapes.   India's Biological Diversity Act 2002 aims to promote conservation, sustainable use and equitable sharing of benefits of India's biodiversity resources. This article focuses on Western Ghats (Biodiversity hotspot of the country) for its enormous amount of   medicinal wealth. The value of which is more or less to a large extent restricted to experts in the field and to the traditional folks. Spatial database of medicinal plants gives location specific information of the species and the area to be conserved. It is located at http://wgbis.ces.iisc.ernet.in/biodiversity/database/database.htm . This endeavour brings out the enormous amount of medicinal plants available in the study area, their distribution and their value for human life and Indian economy. The database also tries to emphasize on the species that are endangered (due to their over exploitation) and require immediate conservation strategies for their sustenance. The spatial database created for ecologically and biologically rich areas and on important species would surely add to the conservation endeavour to ensure the sustainability of nature's wealth for future.

Introduction

The earth is home to a rich and diverse array of living organisms, whose genetic diversity and relationships with one another and with their physical environment constitutes biodiversity (variability among living organisms from all sources and the ecological complexes of which they are part, which includes within species, between species and of ecosystems). This biodiversity is the natural biological capital of the earth, and its conservation and sustainable management presents important opportunities for all nations, especially India.

Over the centuries, people in India have had a fascination and respect for the natural heritage, traditional plant ethics and tried to conserve it in varied ways possible. The sacred grooves (considering certain flora or biotic elements as divine) is an unique tradition which has been responsible for preserving pockets of biodiversity in various parts of the country (Khan T.I, 2001). India, while following the path of development, has been sensitive to the needs of conservation. India's strategies for conservation and sustainable utilization of biodiversity in the past have comprised of providing special status and protection to biodiversity rich areas by declaring them as national parks, biosphere reserves, ecological fragile and sensitive areas. One such area is the Western Ghats which runs majestically parallel to the west coast of India. Conservation of the rich biological wealth of Western Ghats turns out to be a priority. And, the richness of the Western Ghats is further increased by the exclusive varieties of medicinal plants that the Ghats has to its credit.

Western Ghats

India is endowed with a variety of natural resources. All along the west coast the Western Ghats are sprawling. The entire Western Ghats is known for its biodiversity, richness and endemism of different species.

The Western Ghats is richly credited with varied kind of vegetation and unimaginable topographical features. Biogeographically, the hill chain of the Western Ghats constitutes the Malabar province of the Oriental realm, running parallel to the west coast of India from 8 ° N to 21 ° N latitudes, 73 ° E to 77 ° E longitudes for around 1600 km. Rising up from a relatively narrow strip of coast at its western border, the hills reach up to a height of 2800 m before they merge to the east with the Deccan plateau at an altitude of 500-600 m. The average width of this mountain range is about 100 km. This bioregion is highly species rich and under constant threat due to human pressure, and is considered one of the 18 biodiversity hot spots of the world. With its complex, heterogeneous landscapes and high levels of biodiversity, it forms an ideal ground for the testing and elaboration.

The tropical climate complimented by heavy precipitation from southwest monsoon and favourable edaphic factors create an ideal condition for the luxuriant growth of plant life, which can be seen only in few parts of the world. With its rainfall regime, the western slopes of the Ghats have a natural cover of evergreen forest, which changes to moist and then dry deciduous type as one comes to the eastern slopes. The vegetation reaches its highest development towards the southern tip in Kerala with rich tropical rain forests.

The Western Ghats presents a whole range of gradients, both altitudinal as well as latitudinal in climatic factors, such as total annual rainfall, maximum temperatures. This tremendous environmental heterogeneity found across the Ghats, of topography, soils, rainfall, number of dry months per year and temperature, makes for an extremely environmentally heterogeneous biogeographic area, with a tremendous amount of diversity, both plant and animal (Gadgil, 1996b).

Species Diversity: Spatial Distribution

The plant species known to be from the Western Ghats is about 4500 species out of which 35 percent are endemic. Levels of endemism in this area are high – nearly 2000 species of higher plants, 84 species of fishes, 87 species of amphibians, 89 species of reptiles, 15 species of birds and 12 species of mammals are endemic to the Western Ghats (Daniel, 1997). Three major gradients in the distribution of this diversity, especially for flowering plants, have been recognized (Gadgil, 1996b). The first and major one occurs along the north-south direction, species diversity increases as one travels from north to south direction along the Ghats. Southward increase of number of rainy days can be related to this phenomenon. The decrease in rainfall, relates to the decrease in diversity from west to east. The third known gradient is an increase in number of plant species found with the increase in temperature, as one goes from higher elevation hills to lower coastal plains. This heterogeneous condition, which is affluent all along the ranges and regions of the Western Ghats makes it an ideal ground for the luxurious growth of plants with therapeutic value. But since the region is being uncontrollably invaded by urban development and human settlements, life of such valuable medicinal wealth is at stake. And with the patronage of herbal medicines and their products increasing, there is an urgent need to conserve the endemic diversity in the medicinal plants before it is wiped out from nature. Therefore, collection and cultivation of such species and the conservation of their genetic traits by genetic engineering and tissue culture techniques is the present day call for conservationists.

Medicinal Plants

Plants have been used as healers and health rejuvenators since time immemorial. Even now, WHO recognizes that medicinal plants plays an important role in the health care of about 80 percent of World population in developing countries and depend largely on traditional medicines, of which herbal medicines constitutes the most prominent part (Fransworth et al. 1985). The rest of the 20 percent also depend substantially on the plant-based medicines.

Among the rich and varied plants of Indian forests the medicinal plants constitute an important source, the use of which for human and veterinary health care has probably continued, in an unbroken tradition for well over 2 millenium.

Many people have defined medicinal plants in many ways, out of which the accepted definition given by the Agricultural and Natural Resource Development is,

            “ Plants that are recognized by people to have reliable and effective medicinal values, are commonly used in treating and preventing specific ailments and diseases, and play an essential role in health care.”

The number of medicinal plants in India, both indigenous and introduced has been estimated to be between 3,000 to 3,500 species of higher plants. The Glossary of Indian Medicinal Plants has listed around 3,000 plants (Asolkar et al., 1992; Chopra et al., 1956, 1974). Two thousand five hundred plants have been reported to be used in ethno-medicine (Jain, 1991). The number of plants listed in Ayurvedic Materia Nighantu is 560 in Bhav Prakash Nighantu (Kumar 2000). The Ayurvedic Drug Formulary prepared by Department of Indian System of Medicine, lists 387 plants (Sarin, 1996). The Unani system of medicine describes 440 plants (Said, 1969) out of which 360 are common to other systems practiced in the country. The number of plants having confirmed therapeutic properties or yielding a clinically useful chemical compound thus lies around 700 species. The occurrence of these medicinal plants and availability of raw materials from them is as follows:

•  Plants occurring wild in forests, grasslands, aquatic and desert ecosystems, associated with other forms of natural vegetation.

•  Plants growing as weed.

•  Plants cultivated as ornamentals or as cereal, fruit, vegetable, spice, oil seed, essential oil or other cash crop.

•  Plants cultivated as medicinal crop.

In addition, almost 25% of the entire compounds of current prescription drugs were derived originally from plant sources (Balandrin et al, 1985). Of the estimated 25,000 flowering plant species in the world today, only about 10% have been scientifically examined for their medical application, mostly in rudimentary way. Undoubtedly, many more plant-derived medicinal substances await discovery (Akerale et al. 1991). The information on the medical wealth of these examined 10% of plant species is scattered in different sources.

The Western Ghats is very rich in its medicinal wealth. The forests and hills of this region   is a treasure house of about 700 medicinal plants. Out of which some are used for traditional and folk medicinal practices. Many are exploited commercially for their active enzymes and their commercial value.

Medicinal plant species of Western Ghats represent a variety of life form ranging from lichen, algae, herbs, shrubs, climber and trees, which are annuals to perennials. Moreover these species are distributed from canopy to understorey and are characterized seasonally. The auto-ecology and syn-ecology of medicinal plant species is complex and their proper understanding requires a sound knowledge of the ecology, taxonomy and ethno-botany for these species. Western Ghats with its species diversity is a treasure house of different kinds medicinal plants.

The limited knowledge on the varied use of the medicinal plants, their availability and extent of distribution weakens the ways to utilize these resources efficiently. Therefore, it is required to bring the information in various sources into one roof.

Importance of medicinal plants

From the trade data available, it is clear that the global market for medicinal plants has always been very large. To give an example of the extent of trade volumes even at that time, according to one report commissioned by the World Wide Fund for Nature, the total import in 1980 of “vegetable materials used in pharmacy” by the European Economic Community was 80,738 tons (Lewington 1992). India was the largest supplier by far, with 10.055 tons of plants and 14 tons of vegetable alkaloid and their derivatives. It is also true that due to the rising international demand, many important medicinal plant species are becoming scarce and some are facing the prospect of extinction. Therefore it is important to conserve the extensively traded medicinal plants in its natural environment or cultivating it in favorable environments.

Out of the large variety of species available in the Western Ghats, about 50 species hold a very high value in the folk and herbal health forms for the treatment of different forms of ailments. The most common plants like the Mimosa pudica, Hibiscus angulosus, Leucas aspera, Phyllanthus neruri, Calotropis gigantea, Tridax procumbens, Parthenium hysterophorus (which is considered to be a noxoious weed) are all found to have cure for many major ailments like jaundice, asthma, piles, bronchial and blood disorders.

Plants like Anona squamosa, Buchanania lanzan, Semecarpus anacardium, Dioscorea bulbifera and Aphanamixis polystachya are recommended for various forms of tumor. Plant parts of Pepper (fruit) and Cinnamom (bark) when mixed together make up a very strong formula for curing Migraine. Frequent doses of medicinal plant extracts of Rhincanthus nasuta, Momordica dioica, Cinnamomum zeylanicum, Ophiorhizza mungos relieves cancer patients. The spread of knowledge on the natural wealth is more important for a country like India, at a time when the synthetic drugs are stealing the economy rates

  Most of the medicinal plants are found to occupy forest types like deciduous forests, evergreen forests and they are found in fallow lands and wayside. It can be noted that the plants that were very common in the area when they were first studied have got into the IUCN Red List over the years. Rauvolfia serpentina, Saraca asoca, Gymnema sylvestre, Gloriosa superba, Strycnos nux-vomica are included in the list which are very rich in their medicinal strength but are in the verge of extinction. The Western Ghats also hosts many medicinal plants that are endemic to the area. Appropriate conservation strategies have to be implemented immediately to protect the fragile habitats of many such medicinal plants. The information on few of the endemic species is gathered and a region specific list is given below.

Endemic Species

The medicinal plant species of   Western Ghats which are categorized by the IUCN is listed below.

IUCN categorized species

The conservation of these species in specific and a search for natural alternatives to these would pave way for excavating the hidden medicinal wealth in many other widely available plants in the region.

Western Ghats was and will remain an area where the therapeutics of nature can be excavated. So efforts have to be taken to bring to limelight the use of nature's doctors, methods to conserve them and to sustain their existence for the future generations.

*Address for Correspondence

Energy & Wetlands Research Group,
Center for Ecological Sciences,
Indian Institute of Science,
Bangalore - 560 012.