- Having “islands” of trees peppered across oil palm plantations can boost the biodiversity of the landscape while maintaining crop yields, a new study shows.
- Researchers found that biodiversity and ecosystem functioning improved within five years of planting these tree islands, with larger patches providing greater benefits for species such as birds and bats.
- Though these islands can boost biodiversity, the study authors underline that they are no replacement for protecting natural forests.
- “It is very important for conservation to maintain natural forest and avoid deforestation as the top priority,” said first author Delphine Clara Zemp.
Planting clusters of native trees in oil palm plantations can boost biodiversity without sacrificing yields, according to a new study.
Researchers say the findings from an experimental project on the Indonesian island of Sumatra, published in the journal Nature, could be implemented by the industry to provide refuge for a range of species.
“By planting these tree islands, we can see that diversity of multiple groups, from soil bacteria to birds and bats, increase,” Delphine Clara Zemp, first author on the paper and the head of the Conservation Biology Lab at the University of Neuchâtel in Switzerland, told Mongabay in an interview.
“Having tree islands in the matrix of oil palm, which is a harsh environment, could potentially facilitate the movement of species in this landscape.”
The international team, led by researchers at the University of Göttingen in Germany, also noted that tree islands improved ecosystem functioning, impacting water regulation, nutrient cycling and pollination. “We found that there are also significant enhancements in our tree islands compared to conventional palm plantations,” Zemp said, adding that in terms of the size of the tree islands, the results showed that larger patches are better for biodiversity.
Though oil palm trees were thinned to allow space for other trees within the plantations, this didn’t result in a drop-off in yield. That’s because palms surrounding the islands actually increased their yields, Zemp said, largely compensating for any losses.
“After just five years of restoration, the results obtained are impressive,” Benoît Goossens, director of the Danau Girang Field Centre in Malaysia, who was not involved in the study, told Mongabay in an email. “The findings are highly significant because it shows that any forest fragment, any patch of trees, in an oil palm landscape has its ecological importance and can act as steppingstones for many species that use the landscape.”
Besides supporting biodiversity, the tree islands “could also potentially benefit from the ecosystem services that directly result from the better functioning of the ecosystem,” Zemp said.
Though these islands can boost biodiversity, the study authors underline that they are no replacement for protecting natural forests. Higher numbers of species were found within the islands, but these were generalist species and those less sensitive to human disturbance. “It is very important for conservation to maintain natural forest and avoid deforestation as the top priority,” Zemp said.
Goossens agreed that it’s important not to send the “wrong message” that clearing forests is acceptable as long as fragments are kept or regrown within plantations.
“The biodiversity you regain by restoring those patches will not reach the level of biodiversity you had in a natural forest,” he said. But he also said the palm oil industry should learn from the study and implement tree islands within existing plantations: “I would even encourage the industry to keep/restore as many patches as possible, of different sizes.”
Banner image: A green crested lizard in Borneo. Though the study findings offer a route to boost biodiversity and provide refuges in palm plantations, the researchers stress that protection of natural forest is paramount. “Our results demonstrate that enrichening oil-palm dominated landscapes with tree islands is a promising ecological restoration strategy, yet should not replace the protection of remaining forests,” they write. Image by Erik via Flickr (CC BY-NC-SA 2.0).
Zemp, D. C., Guerrero-Ramirez, N., Brambach, F., Darras, K., Grass, I., Potapov, A., … Kreft, H. (2023). Tree islands enhance biodiversity and functioning in oil palm landscapes. Nature, 618(7964), 316-321. doi:10.1038/s41586-023-06086-5