When Is a Rainforest Not a Rainforest?


Last Thursday’s New York Times published a fascinating article, “New jungles prompt a debate on rainforest,” where two well-known Smithsonian scientists traded interpretations about the meaning of regeneration of rainforests in Panama.

Not the least of the issues the article raised was the climate around the Smithsonian office watercooler these days, as Drs. Joe Wright and Bill Laurance played out a dynamic that in the natural world would amount to two large horned and horny mammals locking resplendent headgear.

Dr. Wright rightly notes that there’s a lot of regenerating rainforest around the world, so maybe the cup’s half-full and getting fuller.

Dr. Laurance equally rightly notes that there’s lot of rainforest getting ploughed under in places other than Panama, so maybe the cup’s half-empty and getting emptier.

Who’s more right?

I often think about environmental history, and it illuminates this particular argument. One of the times I think about it is during my walks in the Tijuca forest, above the city I’ve lived in for the last three years and loved for much longer, Rio de Janeiro.

Rio is most famous for its beaches — but its true glory is the forest above the beaches, where a network of roads and forest paths wends its way through one of Brazil’s first national parks, Tijuca. The park was formally created in 1937 but is in effect much older, since the whole area was loved by Brazil’s last Emperor, Dom Pedro II, and much of it has been protected since the mid-19th century.

But the astonishing thing, as you wander through the apparently mature rainforest, with its toucans and orchids, is that much of what is now forest was actually a coffee plantation as little as a century ago. Photos show the hills now covered in dense forest covered in equally dense rows of coffee bushes, as orderly and man-made as the forest now seems wild and natural.

Old Emperor Pedro was an early proponent of mixed-use forests. He rented out chunks of the royal forest to coffee growers, and used the money to protect the rest. The coffee bushes were pulled up around the time of the First World War, and the forest grew back. You would need to be an expert botanist now — I’m not — to be able to distinguish the old-growth from the newer forest today.

We think of tropical forests as porcelain-like, fragile and impossible to put back together if broken. Tijuca backs up Dr. Wright’s argument that it’s more accurate to view tropical rainforests as tough and resilient, able to absorb a huge amount of punishment and come back.

But I also think of the last time I visited Lucas do Rio Verde, in Mato Grosso, a thousand miles north of Rio, three years ago. I walked through another forest by the banks of the Rio Verde, the Green River. It’s not there anymore — or rather it is, but underwater. A small dam, not one of the large projects that makes headlines, snuffed it out like a candle. No Tijuca option there. It was the last forest fragment for miles around.

So long as the impact of economies is to fragment forest cover rather than remove it wholesale, there is a chance of regeneration. So there are certainly grounds for optimism for the tropical forests of Central America, the Congo basin and elsewhere, where fragmentation is the rule rather than the exception. But there are places where large-scale conversion rather than fragmentation is the rule, and Mato Grosso is one of them.

I think Laurance overstates his case; he doesn’t recognize that there are gradations of rainforest instead of virgin forest and degraded forest. I also think Laurance should read the extensive literature that shows the intensive interplay between human societies and tropical forests in places like the Amazon, and at least make an effort to understand how historically problematic the notion of a virgin rainforest is.

But in pointing to the scale and sheer destructiveness of threats to the rainforest in a globalizing world, Laurance is more right.


(Image: Tujica forest. Credit: Abrivio under a Creative Commons license.)

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