Each year, thousands of hectares of rainforest and other forest ecosystems such as rubber plantations are converted into oil palm plantations.
Photo: © Rich Carey/shutterstock

Converting rainforest into palm oil plantations

Land-use intensification in the tropics plays an important role in meeting global demand for agricultural commodities but generates high environmental costs. A study by researchers of the German University of Göttingen analysed the carbon costs and benefits of converting rainforests into oil palm plantations, drawing on comprehensive data on the soil and vegetation in central Sumatra, Indonesia.

Each year, thousands of hectares of rainforest and other forest ecosystems are converted into oil palm plantations in order to meet the growing demand for the oil world-wide. Indonesia and Malaysia account for nearly 85 per cent of global palm oil production, and in 2012, Indonesia had the highest deforestation rate in the world.

According to a recent study conducted by a consortium of researchers at Germany’s University of Göttingen, converting rainforest land into oil palm plantations leads to extremely high carbon emissions. One hectare of converted land equates to a loss of 174 tons of carbon, and most of this carbon will find its way into the air as CO2.

This loss estimate is higher than the figure published by the Intergovernmental Panel on Climate Change (IPCC) to quantify the amount of greenhouse gases emitted by oil palm farming; it is also higher than the figure used by sustainable palm oil certification bodies. Furthermore, the study shows that carbon loss in the soil needs to be considered.

Intensive rubber farming, on the other hand, is associated with a loss of 159 tons of carbon and extensive rubber production a loss of 116 tons. This difference between oil palms and rubber plants is largely explained by the shorter plantation rotation time of oil palms. However, oil palm farming is more efficient than intensive and extensive rubber farming in terms of the number of tons of biomass produced annually versus the resulting loss of carbon.

How to reduce the short-term environmental impact of rubber and oil palm cultivations

The study offers practical advice on reducing the short-term environmental impact of both rubber and oil palm cultivation. For one thing, conversion of forests into oil palm plantations should be done only if the wood that is felled can then be used – e.g. for construction purposes – without being burned. In addition, a thicker layer of vegetation should be left on the ground as a natural fertiliser and to reduce surface run-off in converted ecosystems. Finally, the waste from palm oil mills should be returned to the plantations as additional organic fertiliser.

Looking at the long-term effects, Stefan Scheu, leader of the research project and co-author of the study, points to integrated approaches including residue management and planting other tree species with oil palms to improve sustainability. “Residues of palm oil fronds may be used as mulch and organic fertiliser to increase nutrient availability and prevent surface run-off and erosion,” Scheu says and adds that recent results of the project indicate that planting more tree species into oil palm plantations may help to mitigate some of the negative environmental impacts of oil palm monocultures without reducing the yield of oil palm and income of farmers.

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More information:

Reference: Thomas Guillaume et al. “Carbon Costs and Benefits of Indonesian Rainforest Conversion to Plantations”. Nature Communications (2018). doi: 10.1038/s41467-018-04755-y