Now here’s a whopper of a project: restoring Brazil’s Atlantic forest, which covered 330 million acres when the Portuguese  arrived in 1500 but has since been reduced to 7% of that (or about 20 million acres, most of which is quite fragmented). It is now home to 130 million people, or 70 percent of Brazil’s population.

The Nature Conservancy is known for buying land to preserve it, but it can’t afford to buy up enough land in Brazil’s Atlantic Forest region to increase the current forest to 30 million acres. Instead, TNC intends (1) to create corridors between remaining fragments of the Atlantic Forest, allowing species from different areas to breed and thus diversify their gene pool and (2) reforest the most important areas, along streams and on steep slopes. Doing so will go a long way toward improving water quality in the cities of the Atlantic region (Sao Paulo and Rio de Janeiro), since forests along streams keep heavy rains from washing sediment into the water supply.

Here is the simple but ingenious plan: plant 1 billion trees by 2015, at a cost of about $1 billion. Yes, that’s $1 per tree.

One way to pay for this: charge cities a fee and use the money to pay farmers to plant trees along streams (which, by law, they’re supposed to be doing anyway).

I first read about this project in Nature Conservancy‘s Summer 2008 issue. Here’s a quote that illustrates the complexity of restoring a forest:

Around 70 percent of the saplings [Mario Barbosa] Rosa Filho plants are fast-growing pioneer species, and the other 30 percent are slower-growing species. The pioneers provide shade for the slow growers, which will make up part of the reconstructed forest. The slow growers provide further conditions for a third group of species, to be planted later, that will eventually compose a large part of the finished forest.

Most likely the Atlantic Forest will never be what it was 500 years ago. But with determination, we can restore some of it, preserving the 1,000 species of birds (200 endemic) that live there, and enabling the local inhabitants to continue to live off the forest, as they have for generations.