The original landscape? (Image: Martin Harvey/Corbis)

WHAT is a vast grassland doing in the middle of the world’s largest rainforest? Conservationists say that fires started by the indigenous Pemón people have destroyed the forests that should naturally blanket the area, and that fires should be banned. Others argue that the savannah has existed for millennia and that the fires conserve this natural landscape. Both could be wrong.

New research shows that human fires did help shape the landscape, but only after a portion had already become savannah. Some think that burning land could even help protect the remaining forest.


The Gran Sabana looks like an anomaly. It’s part of a 68,000 square kilometre island of savannah in the lush rainforests where Venezuela meets Brazil and Guyana (see map). There have been many different theories about how it formed in a region where the climate favours rainforests, and plenty involve fire.

The Pemón set thousands of fires each year. It helps them communicate and hunt, and they believe it has magical healing powers. Such spiritual connotations might explain why some view the Pemón’s fire use as irrational and dangerous, says Iokiñe Rodríguez, at the University of East Anglia, UK.

But was it their fires that first carved the savannah out of the rainforest?

To find out, Valentí Rull at the Institute of Earth Sciences Jaume Almera in Barcelona, Spain, and his colleagues examined ancient pollen in lake sediments, which provide a record of the plants growing in the region stretching back thousands of years. The record shows that about 12,000 years ago – 1000 years before any evidence of people on the Gran Sabana – the landscape was already a mosaic of patches of savannah and forest (Quaternary Science Reviews, doi.org/5pp).

“Savannahs in general predate human activities,” says Colin Hughes at the University of Zurich in Switzerland. Hughes says this is evidence that such grassy regions developed through a set of feedback loops between climate, natural fires and vegetation.

Rull’s team also found that the savannah expanded dramatically after the arrival of humans – and peaks in the quantity of ancient charcoal trapped in the lake sediments suggests human fires may have played a role.

However, fires lit by humans might not shoulder all the blame. A rapid extinction of large grazing animals caused by hunting might have meant uneaten grass building up in the small savannah patches. This would then burn uncontrollably and destroy forests if set alight by, say, a lightning strike.

“This region will become a huge fireball – we won’t have control anymore once our elders die”

So, rather than threatening the forests, human fires might be vital for saving them, says Rodríguez. Experiments on the Gran Sabana show that controlled burning of land is an effective way to create firebreaks that last for several years and can potentially keep destructive wildfires in check. “The trick is actually to have a system where there is a prescribed programme of fires carried out at the correct time of year,” she says.

The message is beginning to affect government policy elsewhere. “In Australia, for instance, the government has acknowledged the need to reincorporate this knowledge into its official fire management practices,” says Rodríguez. “But their tragedy is that many [Indigenous Australians] have been displaced from their traditional lands, so the ancestral knowledge isn’t rooted anymore.”

The Pemón are still tied to their traditional lands. But their way of life is changing. Many now live in large towns, rather than in settlements scattered across the landscape, and the traditional knowledge on fire management is disappearing as elders die.

Rodríguez cites a Pemón woman she interviewed in her research: “We really have to think what will happen when all our elders die. This region will become a huge fireball – we won’t have control anymore.”

This article appeared in print under the headline “Fires shape the Amazon savannah”