First large-scale map of oil palm plantations reveals big environmental toll
Rhett A. Butler, mongabay.comMarch 07, 2011

Distribution of closed canopy oil palm plantations and tropical peatlands in the lowlands of Peninsular Malaysia, Borneo and Sumatra. Click image to enlarge.
The research, published in the journal, Proceedings of the National Academy of Sciences (PNAS), finds that closed canopy oil palm plantations covered 8.3 million ha in 2010, including 2 million ha in Peninsular Malaysia, 2.4 million ha in Borneo, and 3.9 million ha in Sumatra. The analysis is conservative: it only accounts for mature plantations—those established in 2002 or earlier—that are over 200 ha. But while the map excludes smaller and/or immature plantations (thought to cover at least another 3 million ha in Malaysia and Indonesia), the work represents an important development in determining the extent of oil palm expansion in Southeast Asia.
"The same tool can be used in other regions, such as Africa or Latin America, experiencing oil palm development."
Projecting environmental impacts
Importantly, the tool can be used to extrapolate the environmental impact of oil palm expansion. The authors did just this with two areas that are of major concern to environmentalists: biodiversity and carbon emissions.
Koh and colleagues applied a species-area model to the map to estimate biodiversity loss from land use change.
![]() The government of Sarawak recently announced it intends to convert more than 1 million ha of forest and peatlands for oil palm. Much of the area targeted for conversion is Native Customary Rights (NCR) land. |
Other studies have shown oil palm plantations house substantially fewer species — up to 80 percent less — than natural forests.
Koh and colleagues also estimated the climate impact of oil palm expansion.
Comparing the map with known peat forests, they found that at least 880,000 hectares of carbon-dense swamps had been converted to plantations by the early 2000s, contributing to the loss of more than 140 million metric tons of above-ground carbon stocks and resulting in annual carbon emissions of at least 4.6 million tons from peat oxidation.
"Our estimates of carbon emissions were based on a very recent review (PNAS 107:19655) of the carbon balance between intact peatswamp forests and oil-palm plantations in Southeast Asia, which takes account of aboveground biomass carbon, belowground peat oxidation, as well as forfeited carbon sequestration services due to lost forests," Koh told mongabay.com via email. "Therefore we used the latest estimates of these emissions variables that are also specific to our study region."
Restoration of these lands could boost local biodiversity but conversion to oil palm would exacerbate greenhouse gas emissions. Thus Koh and colleagues conclude with a call to prioritize conservation and reforestation efforts in regions that retain the bulk of remaining peatswamp forests in Southeast Asia: Central Kalimantan, Riau, and West Kalimantan. These three Indonesian provinces account for nearly three quarters of remaining peatswamp forests in Peninsular Malaysia, Borneo, and Sumatra.
CITATION: Lian Pin Koh, Jukka Miettinen, Soo Chin Liew, and Jaboury Ghazoul. Remotely sensed evidence of tropical peatland conversion to oil palm. PNAS Early Edition for the week of March 7, 2011. www.pnas.org/cgi/doi/10.1073/pnas.1018776108
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