Tropical Peat Forests in Trouble

Dave Mosher Science Now 29 Apr 11;

Southeast Asia boasts nearly 250,000 square kilometers of peat swamp forests, which host creatures such as orangutans and the world's smallest fish, and store vast quantities of carbon. But these peat swamps are in trouble, according to a new study of deforestation in the region. If people continue to chop, drain, and burn at current rates, researchers report, by 2030 no native swamps will remain and billions of metric tons of carbon will be lofted into the atmosphere.

Almost all peatland in Southeast Asia is found in peninsular Malaysia and an archipelago of islands that includes Borneo and Sumatra. Rain trickles down mountains and through forests there, ultimately ending up in low-laying lands that can't quickly drain. Plant matter can't fully decay and turns into a peaty, acidic stew, trapping carbon and forming a unique environment for wildlife. Although Southeast Asian swamps comprise between 6% and 7% of global peatland, they store roughly 64 billion metric tons of carbon—about nine times the global emissions from fossil fuel combustion in 2006.

Globalization eventually reached Southeast Asia in the 1980s, driving farmers to fell peat forest trees for cash and replace the swamps with palm oil plantations. Earth-monitoring satellites have visually documented such destruction for decades, but researchers had never precisely quantified the loss for the region over a long period of time. Sorting out which pixels in the images belonged to swamps, palm oil plantations, urban areas, and the like is also difficult work that's impossible without well-tuned algorithms. So for 5 years, lead author and ecologist Jukka Miettinen and his colleagues at the National University of Singapore studied maps and developed methods to codify the images. They also incorporated infrared images to gauge the effect of human-set fires in the region.

The results, published online 15 April in Frontiers in Ecology and the Environment, show that peatland forest dropped from 77% of original coverage to 36% between 1990 and 2010. At current rates, no forest will remain in 2 decades. "Even though I have been working in this region for nearly ten years and was well aware of the deforestation taking place in Southeast Asian peatlands, I must say that I was still surprised to see how little peat swamp forest is left," Miettinen writes in an e-mail.

As unique habitat for animals is gobbled up locally—6000 plants and dozens of birds, fish, and mammals live only there—the rest of the planet is bound to feel the effects. Once people drain peat swamps for plantations or urban development, plant material begins to decompose, release carbon dioxide, and fuel planet-wide climate change.

"Nearly all peatlands in Sumatra and Borneo are now sources of carbon emission," says hydrologist Aljosja Hooijer of the National University of Singapore, who works with Miettinen but wasn't involved in the study. Ecologist Sue Page of the University of Leicester in the United Kingdom says that Southeast Asia emits as much as 363 million metric tons of carbon each year through peatland destruction. "That's the same amount of carbon stored in the entirety of England's peatland," Page said. "These new maps really show the extremely rapid rate of deforestation. We knew it was bad, but the scale of destruction here is shocking and frightening."

With an average of 2700 square kilometers of Southeast Asian peat swamp vanishing every year, the situation is dire. One peatland researcher who works in the region, but wished to remain anonymous (for fear of losing his job), said the Indonesian government at all levels is not doing anything constructive to curb the problem. "There is a lot of talk, to please international donors, but no action. It even seems that in some areas that forest clearing has accelerated, to make sure it's done before conservation laws are enforced," the source said. "It is all about political will."