Can you rescue a rainforest? The answer ...( ITHACA N.Y. -- Half a century after ...)

ITHACA, N.Y. -- Half a century after most of Costa Rica's rainforests were cut down, researchers from the Boyce Thompson Institute took on a project that many thought was impossible - restoring a tropical rainforest ecosystem.

When the researchers planted worn-out cattle fields in Costa Rica with a sampling of local trees, native species began to move in and flourish, raising the hope that destroyed rainforests can one day be replaced.

Carl Leopold and his partners in the Tropical Forestry Initiative began planting trees on worn-out pasture land in Costa Rica in 1992. For 50 years the soil was compacted under countless hooves, and its nutrients washed away. When it rained, Leopold says, red soil appeared to bleed from the hillsides.

The group chose local rainforest trees, collecting seeds from native trees in the community. "You can't buy seeds," Leopold says. "So we passed the word around among the neighbors." When a farmer would notice a tree producing seeds, Leopold and his wife would ride out on horses to find the tree before hungry monkeys beat them to it.

The group planted mixtures of local species, trimming away the pasture grasses until the trees could take care of themselves. This was the opposite of what commercial companies have done for decades, planting entire fields of a single type of tree to harvest for wood or paper pulp.

The trees the group planted were fast-growing, sun-loving species. After just five years those first trees formed a canopy of leaves, shading out the grasses underneath.

"One of the really amazing things is that our fast-growing tree species are averaging two meters of growth per year," Leopold says. How could soil so long removed from a fertile rainforest support that much growth?

Leopold says that may be because of mycorrhizae, microscopic fungi that form a symbiosis with tree roots. Research at Cornell and BTI shows that without them, many plants can't grow as w
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