The effects of palm oil production on tigers and other mammals in Sumatra, Indonesia
The Zoological Society of London (ZSL) has been studying the impacts of oil palm plantations on wild mammals in Sumatra, Indonesia since 2001, focusing on the ecology of medium to large terrestrial mammals, particularly the tiger (Panthera tigris sumatrae). Sumatra contains a range of possible wildlife habitats ranging from primary rain forest through degraded forests and scrub to commercial crops such as oil palm. We have examined the habitat matrix on and around oil palm plantations, which consists not only of oil palm crop but also of degraded forests and scrub areas, both on plantation land and in the surrounding landscape.
The results show that the oil palm crop itself contains very low mammal diversity. Of over 40 species identified in the immediate area, less than a third were ever detected within the oil palm crop. Landscape-level surveys showed that all species detected, with the exception of wild boar (Sus scrofa), preferred the degraded forest and scrub areas to the oil palm crop itself. Tigers were studied on the plantation margins using radio tracking technology, camera trapping and pug-mark transects, but were never detected within the oil palm crop. The same technology showed tapirs (Tapirus indicus) and sun bears (Helarctos malayanus) following a similar pattern, but occasionally crossed oil palm through riverine scrub corridors.
However, scrub and degraded forest habitats on and around plantation-owned land retained good mammal diversity, particularly terrestrial species. Twenty-eight species of high conservation value were detected in the immediate vicinity of the plantation (18 IUCN red listed and 25 protected by Indonesian law). Tigers (IUCN: Critically endangered) initially survived well on the plantation margins, probably benefiting from high densities of wild pig, which thrive in and around oil palm plantations.
During the study period, populations of all species found outside the oil palm crop decreased. Tigers had disappeared by 2004. The primary reason was large sale clearing and settling of unplanted habitats by local communities which the plantation was powerless to prevent, despite having set the area aside for wildlife conservation purposes. These settlements also created an increase in illegal hunting, further impacting wildlife numbers.
These results show that the continued expansion of the palm oil industry is likely having a devastating effect through habitat loss on a wide range of mammal species, not only through forest clearance but even when clearing degraded habitats. In addition, oil palm plantations represent significant barriers for wide ranging or dispersing species such as tigers and elephants, further endangering core populations. Further impacts are created by the opening of access to unplanted habitats.
However, the results also show that existing oil palm plantations do have a role to play in mammal conservation, through management of unplanted land set aside for conservation, and/or through establishment of connectivity corridors for core populations – provided that such areas can be kept clear of human settlement.
Finally, the results show that government support is essential in mitigating the environmental impact of oil palm at both the landscape and plantation levels; ensuring that plantation site selection avoids key wildlife areas, encouraging oil palm companies to maintain wildlife habitats around the planted areas on their land and supporting conservation activities that are carried out on site, particularly in terms of law enforcement to prevent settlement and hunting.
Zoological Society of London (2007 - in print) Wildlife conservation and oil palm. Conservation Report
Zoological Society of London (2005) Rapid Survey of the PT Asiatic Persada/PT Asialog oil palm/forest matrix.
Maddox, T.M., Priatna, D., Gemita, E. and Salampessy, A. (2004) Pigs, Palms, People and Tigers: Survival of the Sumatran Tiger in a Commercial Landscape. Jambi Tiger Project Report 2002 – 2004.
posted on 2007-02-23 04:59 UTC by Dr. Tom Maddox, Zoological Society of London