TROPICAL FOREST NETWORK: Biodiversity


Plant-based medicines

APPRECIATING THE BENEFITS OF PLANT BIODIVERSITY



By John Tuxill

From "State of the World, 1999." Copyright í 1999, Worldwatch Institute. Publication is available from Worldwatch Institute, 1776 Massachusetts Avenue, N.W., Washington, D.C. 20036. http://www.worldwatch.org


Corn in Colombia

OF MEDICINES AND MATERIAL GOODS

In a doctor's office in Germany, a man diagnosed with hypertension is prescribed reserpine, a drug from the Asian snakeroot plant. In a small town in India, a woman complaining of stomach pains visits an ayurvedic healer, and receives a soothing and effective herbal tea as part of her treatment. In a California suburb, a headache sufferer unseals a bottle of aspirin, a compound originally isolated from European willow trees and meadow herbs.

People everywhere rely on plants for staying healthy and extending the quality and length of their lives. One quarter of the prescription drugs marketed in North America and Europe contain active ingredients derived from plants. Plant-based drugs are part of standard medical procedures for treating heart conditions, childhood leukemia, lymphatic cancer, glaucoma, and many other serious illnesses. Worldwide, the over-the-counter value of these drugs is estimated at more than $40 billion annually. Major pharmaceutical companies and institutions such as the U.S. National Cancer Institute implement plant screening programs as a primary means of identifying new drugs.


Rainforest herbal medicines in Ghana

The World Health Organization estimates that 3.5 billion people in developing countries rely on plant-based medicine for their primary health care. Ayurvedic and other traditional healers in South Asia use at least 1,800 different plant species in treatments and are regularly consulted by some 800 million people. In China, where medicinal plant use goes back at least four millennia, healers employ more than 5,000 plant species. At least 89 plant-derived commercial drugs used in industrial countries were originally discovered by folk healers, many of whom are women. Traditional medicine is particularly important for poor and rural residents, who typically are not well served by formal health care systems. Recent evidence suggests that when economic woes and structural adjustment programs restrict governments' abilities to provide health care, urban and even middle-class residents of developing countries also turn to more affordable traditional medicinal experts.

Traditional herbal therapies are growing rapidly in popularity in industrial countries as well. FAO estimates that between 4,000 and 6,000 species of medicinal plants are traded internationally, with China accounting for about 30 percent of all such exports. In 1992, the booming U.S. retail market for herbal medicines reached nearly $1.5 billion, and the European market is even larger.




Despite their demonstrable value, medicinal plants are declining in many areas. Human alteration of forests and other habitats all too often eliminates sites rich in wild medicinal plants. This creates an immediate problem for folk healers when they can no longer find the plants they need for performing certain cures -- a problem commonly lamented by indigenous herbalists in eastern Panama, among others. Moreover, strong consumer demand and inadequate oversight of harvesting levels and practices mean that wild-gathered medicinal plants are commonly overexploited.

In Cameroon, for example, the bark of the African cherry is highly esteemed by traditional healers, but most of the country's harvest is exported to Western Europe, where African cherry is a principal treatment for prostate disorders. In recent years Cameroon has been the leading supplier of African cherry bark to international markets, but clearance of the tree's montane forest habitat, combined with the inability of the government forestry department to manage the harvest, has led to widespread, wanton destruction of cherry stands.

In addition to the immediate losses, every dismantling of a unique habitat represents a loss of future drugs and medicines, particularly in species-rich habitats like tropical forests. Fewer than 1 percent of all plant species have been screened by chemists to see what bioactive compounds they may contain. The nearly 50 drugs already derived from tropical rainforest plants are estimated to represent only 12 percent of the medically useful compounds waiting to be discovered in rainforests.


Medicinal plants in Kenya

Most tragically of all, many rural societies are rapidly losing their cultural knowledge about medicinal plants. In communities undergoing accelerated westernization, fewer young people are interested in learning about traditional healing plants and how to use them. From Samoa to Suriname, most herbalists and healers are elderly, and few have apprentices studying to take their place. Ironically, as this decline has accelerated, there has been a resurgent interest in ethnobotany -- the study of how people classify, conceptualize, and use plants -- and other fields of study related to traditional medicinal plant use. Professional ethnobotanists surveying medicinal plants used by different cultures are racing against time to document traditional knowledge before it vanishes with its last elderly practitioners.

For the one quarter of humanity who live at or near subsistence levels, plant diversity offers more than just food security and health care -- it also provides a roof over their heads, cooks their food, provides eating utensils, and on average meets about 90 percent of their material needs. Consider palms: temperate zone dwellers may think of palm trees primarily as providing an occasional coconut or the backdrop to an idyllic island vacation, but tropical peoples have a different perspective. The babassu palm from the eastern Amazon Basin has more than 35 different uses -- construction material, oil and fiber source, game attractant, even as an insect repellent. Commercial extraction of babassu products is a part or fulltime economic activity for more than 2 million rural Brazilians.


White sap (latex) from the chicle

Indigenous peoples throughout tropical America have been referred to as "palm cultures." The posts, floors, walls, and beams of their houses are made from the wood of palm trunks, while the roofs are thatched with palm leaves. They use baskets and sacks woven from palm leaves to store household items, including food -- which may itself be palm fruits, palm hearts (the young growing shoot of the plant), or wild game hunted with weapons made from palm stems and leaves. At night, family members will likely drift off to sleep in hammocks woven from palm fibers. When people die, they may be buried in a coffin carved from a palm trunk.

Palms are exceptionally versatile, but they are only part of the spectrum of useful plants in biodiverse environments. In northwest Ecuador, indigenous cultures that practice shifting agriculture use more than 900 plant species to meet their material, medicinal, and food needs; halfway around the world, Dusun and Iban communities in the rainforests of central Borneo use a similar total of plants in their daily lives. People who are more integrated into regional and national economies tend to use fewer plants, but still commonly depend on plant diversity for household uses and to generate cash income. In India, at least 5.7 million people make a living harvesting non-timber forest products, a trade that accounts for nearly half the revenues earned by Indian state forests.


Dani warrior in New Guinea

Those of us who live in manicured suburbs or urban concrete jungles may meet more of our material needs with metals and plastics, but plant diversity still enriches our lives. Artisans who craft musical instruments or furniture, for instance, value the unique acoustic qualities and appearances of the different tropical and temperate hardwoods that they work with -- aspects of biodiversity that ultimately benefit anyone who listens to classical music or purchases handcrafted furniture. Among the nonfood plants traded internationally on commercial levels are at least 200 species of timber trees, 42 plants producing essential oils, 66 species yielding latexes or gums, and 13 species used as dyes and colorants.

As with medicinals, the value that plant resources have for handicraft production, industrial use, or household needs has often not prevented their local or regional decline. One of the most valuable non-timber forest products is rattan, a flexible cane obtained from a number of species of vine-like palms that can grow up to 185 meters long. Asian rattan palms support an international furniture-making industry worth $3.5-6.5 billion annually. Unfortunately, rattan stocks are declining throughout much of tropical Asia because of the loss of native rainforest and over-harvesting. In the past few years, some Asian furniture makers have even begun importing rattan supplies from Nigeria and other central African countries.


Shaman in Brazil

On a global level, declines of wild plants related to industrial crops such as cotton or plantation-grown timber could one day limit our ability to cultivate those commodities by shrinking the gene pools needed for breeding new crops. More locally, declines of materially useful species mean life gets harder and tougher in the short term. When a tree species favored for firewood is over-harvested, women must walk longer to collect their family's fuel supply, make due with an inferior species that does not burn as well, or spend scarce money purchasing fuel from vendors. When a fiber plant collected for sale to handicraft producers becomes scarce, it is harder for collectors to earn an income that could help pay school fees for their children. Whether we are rich or poor, biodiversity enhances the quality of our lives -- and many people already feel its loss.


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CONTENTS

HOME

BIODIVERSITY
Benefits of Biodiversity
Traditional crop varieties and food security
Plant-based medicines
The death of global biodiversity
How to save biodiversity

ECOSYSTEMS
Coral reefs
Forests
Endangered Forests [page 2]
Biodiversity of Wetlands
Arctic Biodiversity

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