New techniques help save shrinking tropical forests

Winged beans and "super trees" may help slow the destruction of the world's tropical forests. But without a greater US and international effort, only a few large areas of tropical forest will remain in less than 20 years.

The US stake in wise use of such forests is not widely recognized. But State Department officials point out that the well-being of millions of peasant farmers in South America, Africa, and Asia -- and thus the political stability of their nations -- depends heavily on proper use of these forests.

Yet every year an area of tropical forest the size of the island of Great Britain is destroyed. Every week an area the size of Deleware is cleared. Lowland tropical forests a century ago occupied an area twice the size of Europe. Today about half of that acreage has disappeared.

Peasant slash-and-burn farmers, the main destroyers, get a good crop or two but then the fertility of the thin, fragile soil declines. Often erosion increases and the farmer pushes on to clear more land.

With populations of most tropical nations continuing to climb rapidly, the pressure on remaining forest is mounting.

And as more forests disappear, many plant species native to the areas are disappearing, too -- often before potential uses to the plants can be determined , says Peter H. Raven, director of the Missouri Botanical Garden here.

In a race against the destruction, he and his staff receive some 80,000 plants a year here from around the world. Identified and stored in a large basement room in manila folders, the plants are a record of what exists where.

A small number of researchers in other centers in the United States and abroad are studying practical uses of tropical forest plants. They draw on the kind of data stored at collection centers such as this one to determine what kind of plant they have found and where else it grows.

Dr. Raven, director of the garden, estimates that in Latin America alone there are some 12,000 to 15,000 plants almost totally unknown. Any one of them could have important uses as food, drugs, or fuel, he said in an interview here.

But the total worldwide expenditure by all nations for tropical biology is only about $30 million a year, he says. With so much at stake, wouldn't it be "intelligent" to spend a little more? he asks.

But his and other pleas for more research funding are getting little response in Washington.

There was "a blip of interest" in the topic in the Carter administration, says an aide to Rep. George E. Brown Jr. (D) of California, who is on a subcommittee which recommends funding such projects. "It's very difficult to get someone turned on to [the problem of] deforestation," he aide says.

Congressional hearings last year on tropical forests have produced no legislation or funding. The US foreign aid program is being cut back by President Reagan, though just how will depend on Congress.

But research to date is showing some significant results. For example:

* On once-denuded hillsides in Indonesia, use of fast-growing "super trees" has slowed erosion and added nutrients to the soil, allowing peasant farmers to move on less often to clear new forest land.

* In many other nations with tropical forests, farmers are being introduced to the winged bean, a "soybean of the tropics." Almost every part of the plant, including its roots are edible.

The winged bean's use was once limited almost entirely to small farms in New Guinea's tropical forests. The tall-growing type of leucaene, or "super tree," was found by a University of Hawaii professor in the tropical forests of Central America in the 1960S.

Some varieties of the tree reach a height of more than 20 feet in one year and about 60 feet in seven years. It is being used in the tropics a a source of pulp, paper, firewood, and for reforestation, says Noel Vietmeyer of the National Academy of Sciences.