Making sure the world hears when a tree falls in the forest

Gliding along the shallow bayou with a jungle of giant petrochemical plants just out of sight, Britain's Prince Philip and a boatload of other international environmental experts watched a graceful parade of osprey, heron, egrets, and cormorants.

The entourage was here in the Armand Bayou Nature Center, just south of Houston, as part of a major effort to spotlight the need to preserves the world's tropical forests.

Of course this 2,100 acre patch of woodlands, open prairies, marshes, and estuaries hardly compares with the tropical forests of South America, Africa, and Asia,which shelter about half the world's surviving species of plants and animals. But director Donald Perkins explains that the very existence of the center demonstrates that ''a healthy, functioning estuarine sanctuary can live next door to a major industrial complex.''

And, he says, plant growth in this nature preserve, which converts carbon dioxide to oxygen, helps to clean Houston's polluted air. Moreover, it captures soil and minerals that might otherwise be washed into the Gulf of Mexico, and uses them to produce an abundance of plant life that supports a rich variety of birds and marine creatures.

The World Wildlife Fund International (WWF) and its president, Prince Philip, want more people to be aware of the importance of such natural areas, and particularly of tropical forests. They hope to put across the message on a global scale that the future well-being of the planet as a whole depends on preserving the ''ultimate recycling system'' of these forests.

WWF experts point to the 7 percent of the earth's land surface still covered by tropical rain forests as a biological ''treasure house.'' The wealth of plant and animal life in these forests, they say, is vital for the agricultural advances which will be needed to feed and clothe the world's escalating population. Maintaining current food sources and developing new ones, plant and animal breeders explain, depends on a constant process of cross-breeding domestic crops with the genetic diversity of wild species.

Another critical role played by tropical forests is in stablizing earth's climactic conditions. As more tropical forests disappear, cloud and rainfall patterns could undergo radical changes adversely affecting weather and growing conditions throughout the world.

Speaking at a Rice University seminar in Houston, Prince Philip said the WWF is sponsoring 53 projects in 14 countries in an effort to control the destructive effects of population pressures and ''overexploitation'' of the natural environment. Thomas E. Lovejoy, a WWF expert working closely with the Brazilian government, told of current efforts to discover how small a rain forest can shrink before its biological resources begin to deteriorate.

The WWF says it is also racing against logging interests in Colombia, where ''3,705 acres of one of the most luxuriant tropical forests in the world'' may go to the highest bidder. Randall Susman, an expert on pygmy chimpanzees in Zaire, told of his battle to protect this rare species' habitat, which he says currently is ''directly in the path of a West German lumber company.''

Not everyone, however, is quite so worried about the current state of the world's tropical forests. Resources for the Future, a Washington, D.C., think tank focusing on natural resource issues, disputes WWF figures on the rate of global deforestation.

Research fellows Roger A. Sedjo and Marion Clawson insist that ''in terms of total forested land, little basis exists for serious concern about the imminent demise of the world's forests.'' But while calling alarm inappropriate, they also caution against neglect. Another fellow at the organization, Winston Harrington, notes that the increasing economic value of tropical forest products has led to some third-world measures to prevent mass deforestation.