Peter Ashton knows nearly everything about a thick patch of rainforest that runs along the ragged mountaintops of southern Sri Lanka, just off the coast of southern India. The Charles Bullard Professor of Forestry can name most of the Sinharaja forest's 400 tree species and many of the hundreds of species that pollinate them.

He needs to know just as much about the people living on its fringe, though, to really understand everything about the forest. Ashton's goal is to create a model for preserving tropical forests from development while improving opportunities for the people who live nearby.

For his work, the environmental arm of the United Nations, UNESCO, recently awarded its quadrennial Sultan Quaboos Prize for environmental preservation to a group that includes Ashton; his son Mark Ashton, a silviculturist at Yale; and tropical ecologists Savitri and Nimal Gunatilleke from the University of Peradeniya in Sri Lanka.

"The tropical forest is immensely important for the people. They use it for food, medicine, and firewood. However, the moment the forest enters the market, harvesting becomes exploitative. And new technologies such as shotguns and chain saws make it easier to harvest," said Ashton.

"Our work is all dedicated to understanding how the forest works so it can be managed more efficiently."

Governments cannot declare a forest completely off limits or the locals won't have a place to gather food and firewood, said Ashton. However, if the law does not protect the forest, it will not survive. People can cut down the forest for quick cash, which might temporarily improve their lives, since they have neither electricity, running water, nor medical care. Unfortunately, once the forest had disappeared, they would be worse off than before.

In Sri Lanka and several other countries, Ashton and his partners are working together through the Harvard Institute for International Development (HIID), and the Smithsonian's new Center for Tropical Forest Science, which they created, to untangle the biological and sociological issues surrounding the increasingly rare islands of undeveloped rainforests.

The 3-by-14-mile section of Sri Lankan rainforest and the people living on its edge have largely escaped development so far because the main method of travel is by foot on slippery mud paths. Due to its isolation and a history of climatic stability, the forest has become a reservoir for biodiversity, harboring more than 830 species of plants -- 70 percent of which are unique to southwest Sri Lanka. For its singularity, UNESCO pronounced Sinharaja a World Heritage Site, a designation which puts it on par with the Great Pyramids of Egypt, said Ashton.

Part of Ashton's research within this venerable forest focuses on creating a deep understanding of the biological web connecting everything from insects to trees to people. "We can then use the application of basic ecology towards solving other problems," said Ashton.

Mapping the location of every tree with a stem larger than a pencil in a 60 acre plot was one project they started in 1993. The researchers use that information to measure the interactions between the different species as well as the processes of growth and death in the whole forest.

At the same time, Ashton and his colleagues have been publishing on everything from the growth and flowering to the genetics of many species of dipterocarps, tropical trees that look like 200-foot-tall broccoli. Fertilizer experiments demonstrated that while nutrition accounted for some of the distribution of trees, moisture and light played a role as well.

While the results of the research might seem obvious to most backyard gardeners, knowing just how much fertilizer and what kinds of slopes it takes to make these trees thrive helps governments to more precisely manage the forest. They will use the information to decide what to conserve and how to replant degraded areas.

Locals, banned from cutting down the trees within the preserve, climb thin vine ladders to the tops of kithul palm trees to gather fruit and to tap sap from its flowers. They grind the dried fruit into flour and convert the sap into a variety of products from a sweet, frothy alcoholic drink called toddy to chunks of boiled sugar called jaggery molded in coconut shells.

Ruben Lubowski '92, now a Ph.D. student studying political economy and government at the Graduate School of Arts and Sciences, spent 20 months after graduation living at the forest edge, climbing trees, drinking toddy, and eating curry every meal. He also survived being constantly bitten by leeches, a meeting with a five-foot Cobra, and bouts of intestinal parasites.

He worked on the socioeconomic component of Ashton's project with Ricardo Godoy, formerly a lecturer at the HIID, trying to pin a monetary value on everything the forest provides for the people living nearby. This includes not only food and wood, but also its value as a watershed, a preserve for biodiversity, a tourist destination, and even as a religious site.

Funded by the Boston-based Conservation Food and Health Foundation and the HIID, Lubowski, found that in even in the wealthier villages, where people work at tea and rice plantations, they still depend on the forest for timber, food, and medicine.

"Basically the forest has an important economic value and it doesn't diminish with development," said Lubowski.

The solution to managing the forest is to take everything about the villagers' lives into account, he said. "If we try to get people not to use forest products, then we have to provide an alternative."

Overall, the goal is to figure out the absolute value of the forest and to use that as a guide to a conservation plan.

"From our research we hope to provide rigorous policy-relevant data to governments," said Ashton.

Already, the Sri Lankan Forest Service, which is also recognized in the prize, is using Ashton's data in planning what to do with the forest. One recent project of Ashton's son Mark has been to set aside a buffer zone around the forest, sowing useful plants between imported Caribbean pine trees. They hope that the locals will be able to harvest what they need from the buffer zone, preserving the pristine core of the rainforest.