Shades of Green: Earth's Forests -- Food & Medicine

A farmers' market selling a variety of edible tropical fruits. Photo courtesy Naomi Woods.

A high proportion of forest species, especially rainforest species, could be useful to humans, either for medicinal properties or food crops. This is yet one more reason to be concerned about the loss of biodiversity: since as many as one in six rainforest species could be directly "useful" to humans, what possibilities are we losing with each species that becomes extinct?

Almost half of today's main food crops were originally discovered in the rainforest. Plants that originated, or still live in the forests provide us with fruits, nuts, and grains -- bananas, oranges, pineapples, avocados, mangoes, papayas, tea, sugar, rice, maize, cashews, peanuts, cloves, vanilla, cinnamon. Coffee. Chocolate. Even our common domestic chicken originated in Indian forests.

Imagine how different our diets would be if any of these food plants had become extinct before it was even discovered. The diverse forest gene-pool holds immense potential. New crops are cultivated from forest species, and genetic material from wild plants can be used to improve harvests from existing crops.

A truck delivers large quantities of citrus fruits. Photo courtesy Naomi Woods.

This point is well illustrated by the following case of the discovery of a new maize species. A blight that attacked commercial American corn crops destroyed nearly half of the harvest; soon after, a new species of maize was discovered in the Mexican forest. It was resistant to the blight, as well as other diseases, and could survive in places previously thought unsuitable for maize. If its genes were transferred into domestic corn plants, it could raise the world's maize production by significantly. But this new species was not discovered until almost too late. This plant lived only in several hectares of mountain forest, which was rapidly being cleared. It was literally only days from extinction when it was found.

Forest plants not only provide us with food, they are also a major source of medicinal drugs. Almost a quarter of drugs prescribed in the United States contain compounds from or based on those found in tropical forest plants. The rosy periwinkle of Madagascar was a little-known species until it was discovered to contain alkaloids that can help cure people of Hodgkin's disease.

A Pacific yew tree, source of the drug Taxol. Photo by Maya Walters.

Over millions of years, plants, animals, even microorganisms have evolved chemicals to suit their particular needs. It is not surprising that some of these compounds could also be useful to us. A substance from the saliva of the Central and South American vampire bat may be able to help prevent heart attacks. The Pacific yew tree contains a compound called Taxol that fights cancer.

Forests are often cleared to make way for large fields of a single food crop. Photo credit Corel Photo Clipart CD.

Twenty species of plants provide 90% of the world's food, and just three of these plants supply more than half -- wheat, maize, and rice. These three plants are mostly suited to cooler climates, while much of the world's population inhabits the tropics.
There are about 30,000 plants that are edible or partially edible, but only 7,000 have ever been collected or grown as food crops.

The winged bean of New Guinea has the potential to become an important food crop. The entire plant is edible -- the leaves, the seedpods, the seeds than can be cooked or ground into flour or even used to make a coffee-like beverage, and the tubers that have more protein than potatoes. The wing bean also raises soil fertility, and it can grow over four meters in just a few weeks.

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