Via Tyler Cowen, a new economic study, inspired by new Nobel-winner Elinor Ostrom, shows that local ownership of tropical forests is the best way to preserve them:

In the first study of its kind, Chhatre and Arun Agrawal of the University of Michigan in Ann Arbor compared forest ownership with data on carbon sequestration, which is estimated from the size and number of trees in a forest. Hectare-for-hectare, they found that tropical forest under local management stored more carbon than government-owned forests. There are exceptions, says Chhatre, "but our findings show that we can increase carbon sequestration simply by transferring ownership of forests from governments to communities".

One reason may be that locals protect forests best if they own them, because they have a long-term interest in ensuring the forests' survival. While governments, whatever their intentions, usually license destructive logging, or preside over a free-for-all in which everyone grabs what they can because nobody believes the forest will last (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0905308106).

The authors suggest that locals would also make a better job of managing common pastures, coastal fisheries and water supplies. They argue that their findings contradict a long-standing environmental idea, called the "tragedy of the commons", which says that natural resources left to communal control get trashed. In fact, says Agrawal, "communities are perfectly capable of managing their resources sustainably".

I'd quibble a bit with that last paragraph: This isn't a brand-new idea. It's actually a lesson that many large conservation groups have slowly—and painfully—learned over the years, in a slightly different context. For much of the twentieth century, many mainstream conservationists thought the best way to protect an endangered slice of nature was often to have the government essentially cordon off the area, making it off-limits to human activity (save for tourists or backpackers) and, hence, keeping it pristine.

But, as I described in a recent piece for The National, this brand of conservation frequently had awful effects—not only did it push thousands, if not millions, of local people around the world off their land and into dire poverty (nature was never as pristine or people-free as those early conservationists liked to think), but it was often a futile way of protecting the environment. In more recent years, fortunately, the big global conservation groups have realized that a more cooperative strategy—working alongside locals to manage common pastures, forests, fisheries—is far, far more effective. And, as the study above confirms, that's not just a romantic myth—it actually works.

(Flickr photo credit: evaruth)