Trees grow on money


Rain forests are returning, but it's economic growth, not environmental activism, that's responsible. "By one estimate," The New York Times reported in January, "for every acre of rain forest cut down each year, more than 50 acres of new forest are growing in the tropics on land that was once farmed, logged or ravaged by natural disaster."

What does that have to do with economic growth? In many tropical countries, farmers and their children are abandoning their hardscrabble farms and ranches for the lure of better lives in cities. In addition, agricultural productivity has improved so much that it takes far less land and many fewer farmers to produce food for the world's population. As a consequence, rain forests are rapidly returning to abandoned fields and pastures.

As a 2006 report in the Proceedings of the National Academy of Sciences noted, this development follows the same pattern of reforestation that was seen in industrialized countries in the 20th century. "Without depopulation or impoverishment, increasing numbers of countries are experiencing transitions in forest area and density," concluded the University of Helsinki environmental scientist Pekka Kauppi. "While complacency would be misplaced, our insights provide grounds for optimism about the prospects for returning forests." The researchers found that forests generally begin expanding when per capita income reaches $4,600.