In Sumatra, Indonesia, an international team of researchers has found an innovative way to restore native trees in oil palm plantations. Their method? Create small islands of trees within the plantation. In just six years, some of the local trees have grown to over 15 metres in height. Clara Zemp, Professor of Conservation Biology at the University of Neuchâtel, co-authored a study describing these results, published in the journal Science.
A challenge for tropical forests
The tropical forests of Southeast Asia, rich in biodiversity, are under serious threat from the expansion of oil palm plantations, encouraged by the growing global demand for palm oil. Faced with this situation, it is crucial to find strategies to restore these ecosystems. Since 2013, an initiative called EFForTS-BEE, led by the University of Göttingen in Germany, has been launched to meet this challenge. This project also brings together several Indonesian universities, including those of Bogor and Jambi.
A key role for tree islands
The study shows that the 52 tree islands created in the plantation encourage the germination of replanted seeds, while attracting local species carried by wind or birds. These islands are also home to trees endemic to the Sundaland region, which includes the Malay Peninsula and Borneo. On the other hand, exotic species (not native to the region) are still very much in the minority in these restored areas.
Decisive local factors
According to Clara Zemp, the diversity of trees in these patches depends little on the proximity of surrounding forests or the presence of isolated trees in the landscape. Instead, local factors such as soil quality and patch size play a central role, even for species specific to tropical forests.
Still a long way to go
Despite these encouraging results, the biodiversity of restored areas remains well below that of intact forests. This underlines the importance of preserving the last remaining patches of natural forest, which are of irreplaceable ecological value.
