Thursday, July 18, 2013

[Conservation / Herpetology • 2013] Effects of Oil-Palm Plantations on Diversity of Tropical Anurans | Threatened Frogs palmed off as Forests Disappear

Limnonectes malesianus

Agriculturally altered vegetation, especially oil-palm plantations, is rapidly increasing in Southeast Asia. Low species diversity is associated with this commodity, but data on anuran diversity in oil-palm plantations are lacking. We investigated how anuran biological diversity differs between forest and oil-palm plantation, and whether observed differences in biological diversity of these areas is linked to specific environmental factors. We hypothesized that biological diversity is lower in plantations and that plantations support a larger proportion of disturbance-tolerant species than forest. We compared species richness, abundance, and community composition between plantation and forest areas and between site types within plantation and forest (forest stream vs. plantation stream, forest riparian vs. plantation riparian, forest terrestrial vs. plantation terrestrial). Not all measures of biological diversity differed between oil-palm plantations and secondary forest sites. Anuran community composition, however, differed greatly between forest and plantation, and communities of anurans in plantations contained species that prosper in disturbed areas. Although plantations supported large numbers of breeding anurans, we concluded the community consisted of common species that were of little conservation concern (commonly found species include Fejervarya limnocharis, Microhyla heymonsi, and Hylarana erythrea). We believe that with a number of management interventions, oil-palm plantations can provide habitat for species that dwell in secondary forests.

Keywords: agriculture; Asia; indicators; inventory and monitoring; protected areas

Duttaphrynus melanostictus                  Microhyla heymonsi 

Threatened Frogs palmed off as Forests Disappear

Oil palm plantations in Malaysia are causing threatened forest frogs to disappear, paving the way for common species to move in on their turf, scientists have revealed.

The study, carried out by the Zoological Society of London (ZSL) describes how forests converted to palm oil plantations are causing threatened forest dwelling frogs to vanish, resulting in an overall loss of habitat that is important for the conservation of threatened frog species in the region.

Scientists travelled to Peninsular Malaysia where they spent two years studying communities of frog species in four oil palm plantations and two areas of adjacent forest. The paper is published in the journal Conservation Biology.

Aisyah Faruk, PhD student at ZSL's Institute of Zoology says: "The impact we observed is different from that observed previously for mammals and birds. Instead of reducing the number of species, oil palm affects amphibian communities by replacing habitat suitable for threatened species with habitat used by amphibian species that are not important for conservation. This more subtle effect is still equally devastating for the conservation of biodiversity in Malaysia."

Amphibians are the most threatened vertebrates in the world, with over 40% at risk of extinction. The peat swamp frog (Limnonectes malesianus) is just one of the declining species threatened due to deforestation. It inhabits shallow, gentle streams, swampy areas, and very flat forests, laying eggs in sandy streambeds. Scientists only found this species in forest areas, and if palm oil plantations continue to take over, the peat swamp frog, along with its forest home, could be a thing of the past.

ZSL's Dr. Trent Garner, a co-author on the paper, says: "Existing practices in managing oil palm are not accommodating the highly threatened forest frog species in Malaysia which urgently need saving."

The planting of oil palm plantations leads to the loss of natural forests and peat lands and plays havoc with ecosystems and biodiversity. ZSL, together with collaborators from Queen Mary University of London, Universiti Kebangsaan Malaysia and University of Malaya, continues to work closely with Malaysian palm oil producers in determining if simple modifications to agricultural practices may bring some of the forest species back into areas planted with oil palm and allow them to survive and reproduce in plantations.

AISYAH FARUK, DAICUS BELABUT, NORHAYATI AHMAD, ROBERT J. KNELL and TRENTON W. J. GARNER. 2013. Effects of Oil-Palm Plantations on Diversity of Tropical Anurans. Conservation Biology. 27 (3):  615–624. DOI: