Palm oil plantations have an overall negative impact on biodiversity, according to research released this week. The study, published in Nature Communications, found palm oil plantations are home to fewer insect species than even intensive rubber tree plantations.

A forests expert at James Cook University, Bill Laurance, said of the research: “The big message is that oil palm is bad for biodiversity, in every sense of the word — even when compared to damaged rainforests that are regenerating after earlier logging or clearing.”

The study, conducted in Sumatra – an Indonesian island famous for its tiger and orangutan populations – found that palm oil plantations contain half the number of insect species that natural forests do.

Worldwide, palm oil is one of the most rapidly expanding crops, with the total area of land devoted to palm oil production tripling in the last 25 years. This expansion has been blamed for the rapid deforestation seen in both Indonesia and Malaysia in recent years.

In Sumatra, roughly 25% of palm oil plantations have been directly converted from forest. Still, Indonesia – one of the world’s leading palm oil producers — plans to double palm oil production by 2020.

The environmental and social consequences of palm oil production have been hotly debated over the past decade, particularly due to the industry’s impact on orangutans.

Losing predators

A decline in predatory insects — which help keep other species under control — was particularly worrying.

Laurance explained:

“This is analogous to the kinds of changes we see in larger animals, such as birds and mammals. The specialists and bigger predators tend to be highly vulnerable, and they’re often replaced by generalist omnivores in disturbed environments.

"For example, you lose tigers and specialised understory birds and gain ‘trash’ species—such as generalist rats—that can live almost anywhere.”

Ecosystem damage

Insects are important in ecosystems because they help recycle nutrients, and are a food source for other species.

The new research shows a clear link between the reduced numbers of species in palm oil plantations, and lower energy transfer and ecosystem function in these regions.

This is bad news for other species that live in the region, such as the orang-utan: if the environment is producing less energy, it will be harder to survive.

Head of the Conservation Biology department at the University of Göttingen, Germany, and one of the paper’s authors, Ulrich Brose, said there could be several reasons for the loss of insects.

“Two potential explanations are the pesticides or insecticides applied at higher levels in oil palm plantations or differences in energy (litter or nutrients) input.”

He said their data couldn’t yet disentangle these causes, however the research team at the University of Göttingen were working towards an answer.