by John Burnett

When the guns finally fell silent in Central America, it was possible to appreciate a whole new dimension of this land bridge between continents. Though it represents less than half of one percent of the world's total land area, it contains an estimated seven percent of the planet's biodiversity.

Four years ago, the seven Central American presidents signed an agreement called the Alliance for Sustainable Development. Among other things, the Alianza, as it's called, recognizes that Central America is not composed of seven separate tropical ecosystems, belonging to seven sovereign republics. Rather, it is a single ecological system whose mammals, migratory birds and germ plasm do not recognize political boundaries.

In what everyone agrees is a remarkably ambitious idea, these countries have agreed in principle to create a single Meso-American Biological Corridor: a network of national and trans-border nature preserves to be interspersed with environmentally benign plantations.

Planners, biologists and lawyers working on the corridor are quick to clarify that they do not envision an unbroken passageway of forest through which a panther could conceivably travel from Guatemala's Peten to Panama's Darien Gap.

"I understand the concept of a biological corridor, but we get lots of opposition when we declare protected areas," says Rodolfo Cardona, director of Guatemala's National Council of Protected Areas. "People think they're under glass and can't be used anymore. It's impossible to create more protected areas. So we're thinking about other ideasmore an ecological corridor that includes humans."

Costa Rica has proved to the rest of Latin America that ecotourism can be hugely profitable. In recent years, tourism has become Costa Rica's biggest industry, surpassing bananas, coffee and timber.

"Those ecological treasures exist across the region, indeed even greater in other areas than in Costa Rica," says Stacy Rhodes, director of regional programs for the U.S. Agency for International Development, based in Guatemala City. "And I think the Central Americans know their economic future is also dependent on the future of the natural resource base."

Central Americans are experimenting with two other types of sustainable development that might fit into this "ecological" corridor: shade-grown coffee plantations and tree plantations.

Conservationists are looking seriously at a type of shade-tolerant coffee as a bird-friendly alternative to coffee that requires full sun.

"In El Salvador, for instance, it wasn't possible to talk about protected areas because El Salvador has only has one percent of its territory covered by forest," says environmental lawyer Marco Gonzalez. "But then we discovered shade coffee plantations contained more than 400 species of birds. In a way, the shade coffee acts as a biological corridor."

In the second example, some government biologists see tree plantations as another - albeit imperfect - way to protect biodiversity in the tropics. Commercially valuable trees provide wildlife habitat until they're cut in 10-15 years, and a new forest is planted.

"This was completely pastureland. Now it's fully covered by about eight species of trees. It has excellent forest coverage. And therefore, we're attracting more and more small mammals and deer and birds to come back to this area," says Costa Rican forester Ricardo Villalobos, surveying a plantation of softwoods used to make popsicle sticks, located about 60 miles east of San Jose.

In spite of its misleading name, the Meso-American Biological Corridor has been gaining notoriety not as a two-thousand-mile-long nature preserve, but as a matrix into which other environmental projects can fit. These ideas include managing forests to preserving indigenous land rights to strengthening national environmental laws.

The U.S. and European governments, private foundations and international development banks have committed some $600 million. The World Bank is the single largest donor, with $160 million.

But already skeptics abound.

"I think the idea is good, but I'm not sure it will work," says Guatemalan activist Magali Rey Rosa - a veteran of many environmental battles. "Our most important protected areas are not protected at all. Now if we're not protecting those important areas, how are we going to connect them?"

And would they want to connect the preserves even if they were truly protected? Some biologists question the whole premise of biological corridors because so little science exists that explains what actually happens inside them. "They are only an idea now," said one prominent ecologist, "an act of faith." Some scientists believe if corridor money is being spent to protect wildlife, it could be better used to add acreage to existing wilderness refuges. But others think that as the environmental movement runs short of ideas, corridors do more good than harm.

"Sometimes they make biological sense, sometimes they don't. They generally make good conservation sense," says Amos Bien, director of the Costa Rican Association of Private Nature Preserves.

"I think the Meso-American biological corridor is probably never going to be completed in its entirety," Bien says. "But I think insofar as parts of it can be made, any single piece that can be added is better than not having it all."

It would be easy to succumb to cynicism. Environmental victories are hard enough to win in the United States, much less in a region saddled with endemic poverty, weak government institutions, and a private sector used to getting it's way.

But one participant pointed out that what's important about the Alliance for Sustainable Development is "the process" that has begun with the presidents' signatures.

"You take conservation for granted in the United States. You invented national parks, you're at the top rung of the ladder," says attorney Marco Gonzalez. "Central America is on the bottom rung. We have a long way to climb. But now we've started."