Of Sumatran tigers and wild boars

Logging of pristine primary forests to make way for palm oil plantations is threatening the survival of the Sumatran tiger while supporting hordes of wild boars, according to studies conducted by Dr Matthew Luskin of NTU’s Asian School of the Environment and his collaborators.

In one study, an international team led by Dr Luskin found that tiger population density doubled in Sumatran forests over the last 15 years, thanks to effective anti-poaching programmes. Using data from hundreds of motion-activated cameras spread across remote forests, they estimated the tiger population in Sumatra to be about 618. The threat of extinction, however, increased due to deforestation of 17% of their habitat between 2000 and 2012. This has left robust breeding populations in only two of Sumatra’s major national parks.

Another study links the expansion of palm oil plantations to the rise of wild boar populations that thrive on oil palm fruit and damage nearby forests. Using data collected over 24 years, Dr Luskin and a team from the US Smithsonian Tropical Research Institute and the University of California, Berkeley, found that wild boar populations grew 100-fold coinciding with nearby oil palm fruit production. The boars then caused the destruction and decline of the smallest forest trees by more than 60% over that time period.

“For years, we saw that plants and small trees on the forest floor were disappearing, but we didn’t understand why,” says Dr Luskin. “We now know pregnant wild boars have been clearing the forest vegetation to build birthing nests.”

The studies “Sumatran tiger survival threatened by deforestation despite increasing densities in parks” and “Cross-boundary subsidy cascades from oil palm degrade distant tropical forests” were published in Nature Communications (2017), DOI: 10.1038/s41467-017-01656-4 and DOI: 10.1038/s41467-017-01920-7, respectively.

This article appeared first in NTU’s research & innovation magazine Pushing Frontiers (issue #13, June 2018).