SCIENCE

Borneo’s Mammals Face a Deadly Mix of Logging and Climate Change

But adding small amounts of land to already protected areas could help save the island’s biodiversity

January 22, 2015

Western Tarsier — The western tarsier, a rare primate species, has lost large amounts of its Borneo habitat to logging. More of that habitat is likely to disappear because of climate change. Frans Lanting/Corbis

Borneo’s mammals are threatened by a one-two punch of logging and climate change, but only a small amount of additional land needs to be protected to safeguard many of the species at risk, scientists report today in Current Biology.

The island of Borneo is home to a stunning array of biodiversity. There are thousands of plants, animals and other species packed into a space a little larger than Texas. Many species—such as the Bornean clouded leopard, the proboscis monkey and several kinds of tree shrews and squirrels—are found nowhere else in the world.

But logging has destroyed large swaths of Bornean forest, often lowland forests that are rich in diversity but that are easier and cheaper for companies to access, remove trees and convert the land to other uses, such as oil palm plantations. Climate change is another threat: shifting temperatures and rainfall will render some habitats unsuitable for the animals that live there. To find out how the two threats would interact, Matthew Struebig of the University of Kent and his colleagues combined a model of deforestation with climate projections. Then the team added expert evaluations of what would constitute suitable habitat for 81 of Borneo’s carnivores, primates and bats.

Climate alone threatens to eliminate 30 percent or more of the habitat for 11 to 36 percent of those species, the researchers found. Adding in deforestation doubled the number of threatened mammals. At least 15 species of carnivores, 8 primates and 21 bats could be at risk of going extinct by 2080.

“We were somewhat surprised with the potentially severe impacts that climate change could have, especially relative to those of deforestation, which are already quite substantial,” says Struebig.

The Sunda clouded leopard is “forest dependent,” notes Struebig. “A reduction of suitable habitat across lowland areas is predicted in our modeling,” but adding more protected areas in higher elevations could mitigate this loss, he says. Sebastian Kennerknecht/Minden Pictures/Corbis

Proboscis monkeys—named for their prominent noses—can be found only on Borneo. They are classified as endangered because more than half of the population has been lost in the last few decades due to habitat loss and hunting. Barbara Walton/epa/Corbis

Crab-eating (or long-tailed) macaques, a type of monkey, are one of many species of primates found on Borneo. Fiona Rogers/Corbis

The Sepilok Orangutan Rehabilitation Centre in Sabah cares for young orangutans orphaned by logging and poaching. Paul Shedlowich/Corbis

The number of bearded pigs in Borneo had declined because of habitat destruction, but the animals are still common. Anup Shah/Corbis

Borneo pygmy elephants are one of the world’s rarest elephant species. As their habitat has been destroyed and degraded, there has been increased conflict between the elephants and humans. Juan Carlos Munoz/Nature Picture Library/Corbis

The greater nectar bat (Eonycteris major), which is found only in Borneo and the Philippines. The new study provides “a mixed outlook” for the species, says Struebig. But conserving small amounts of additional land “would safeguard the species against the effects of environmental change.” Matthew Struebig, Durrell Institute of Conservation and Ecology, University of Kent

Climate changes most affected the lowland rainforests in the model, but suitable habitat for many species shifted upslope. That may end up benefiting animals that can migrate quickly enough, because there has been a tendency in Borneo to preserve mid- to high-elevation lands. That pattern has sometimes been criticized, Struebig says, because lowland regions typically host more species. But the new work suggests that those less-than-ideal protected areas could become more important in the coming years. Adding just a bit more protected land in targeted upland spots could help many species in the long run, the researchers found.

Some lowland species, though, such as the otter civet and large flying fox, would need other types assistance to survive the threats. “These species tend to be at greatest densities in lowland habitat, particularly wetlands. As such they demonstrate the need for continued conservation efforts in peatland areas as well as those climate-safe areas we advocate in the article,” Struebig says.

Conserving additional land in Borneo will require cooperating with the forestry, plantation and oil extraction industries, as these businesses manage large amounts of the island’s forests. “There are already signs that some companies are taking on conservation advice and trying to manage their estates in a sustainable way. However, up until now there has been little effort to target these activities to high-priority areas and specific companies in an objective and transparent way,” says Struebig. “This is what we offer.”

And conservation doesn’t necessarily mean making land completely off limits to these companies. Better land management, planning of roads and felling trees in a targeted way can help to reduce industry’s impact on forest wildlife. Reducing the amount of forest converted to oil palm plantations can also help.

"The public can play their part in these efforts,” Struebig notes, “by insisting that their timber products come from environmentally certified sources, which require these management techniques to be implemented.”