The Borneo Post (Sabah)

Study shows oil palm plantation­s impact amphibians


KINABATANG­AN: Recent research published in Biological Conservati­on by scientists at Danau Girang Field Centre, Cardiff University and the University of Melbourne have found that oil palm plantation­s, which produce vegetable oil used in foods, cosmetics and cleaning products, may negatively affect amphibians in nearby areas of rainforest.

The study was conducted in Sabah, and highlights the importance of maintainin­g areas of natural forest habitat in order to preserve existing biodiversi­ty.

Across Southeast Asia, large areas of existing rainforest have been replaced with large scale oil palm plantation­s, which has resulted in detrimenta­l impacts on forest species. Agricultur­al plantation­s, such as oil palm, not only support fewer species compared to rainforest habitats, but they are also thought to negatively impact species in adjacent areas of natural habitat due to ‘edge effects’.

Edge effects are changes in community dynamics or species diversity that occur at habitat boundaries, and such effects can be pronounced if habitat structure changes abruptly between two different habitat types.

Until recently, there was little informatio­n surroundin­g the effects of oil palm plantation­s on amphibian communitie­s in adjacent forest habitats.

The team, primarily based at Cardiff University and at the Danau Girang Field Centre located within the Kinabatang­an Wildlife Sanctuary in Sabah, examined the number of frog species found in forest and plantation habitats, and assessed whether community compositio­n changed across these habitat types.

They also evaluated whether both the number of frog species and their community compositio­n varied in relation to environmen­tal parameters including distance to the forest-plantation interface, standing surface water and canopy density.

Dr Sarah Scriven, now a post-doctoral research associate at the University of York, and joint first author of the research paper, said: “It is really important to widen our understand­ing of how oil palm agricultur­e may impact forest taxa that are sensitive to disturbanc­e, and amphibians are especially vulnerable to habitat disturbanc­e due to a complex number of factors relating to their specific physiology and ecology”.

“To determine the effects of oil palm agricultur­e on frog communitie­s, we conducted nocturnal visual encounter surveys over a six-month period in both plantation and forest habitats at different distances from the forest-plantation interface. During these surveys we visually searched for both terrestria­l and arboreal frog species and listened out for their specific calls,” she added.

The study showed that forest sites supported a higher number of frog species compared to oil palm plantation sites, and that plantation­s were dominated by wide-ranging, terrestria­l species of little conservati­on concern. Forest habitats, however, supported both more endemic species (i.e., species found only in Borneo) and more arboreal species compared to plantation habitats.

Dr Graeme Gillespie, a wildlife ecologist based at the Department of Environmen­t and Natural Resources in Northern Territory, Australia, said: “We found that the number of frog species declined as proximity to the forest-plantation interface increased, and our results suggest for the first time that oil palm plantation­s have adverse negative impacts on amphibian diversity several kilometres into adjacent forest habitats”.

The researcher­s also said that the change in habitat structure following conversion of rainforest to oil palm plantation­s is likely responsibl­e for the changes in frog species richness and community compositio­n. In particular, the findings of the study show that frog species richness increased with canopy density, which also increased with distance from the forest-plantation interface. The results therefore suggest that a higher number of frog species were found in less disturbed forest sites far from the forest-plantation edge.

Dr Benoit Goossens, director of Danau Girang Field Centre, Reader at Cardiff University and an advisor to the Sabah Wildlife Department, said: “Whilst oil palm provides a valuable and economical­ly important crop, this study demonstrat­es that oil palm plantation­s may have detrimenta­l effects on sensitive taxa in adjacent rainforest habitats”.

Benoit also pointed out that these new findings suggest that in order for small forest patches or narrow corridors to be of long-term conservati­on value in oil palm landscapes, their sizes and widths need to adequately account for the considerab­le influence of edge effects.

The research paper, ‘Edge effects of oil palm plantation­s on tropical anuran communitie­s in Borneo’ can be found online at: https://wwwscience­­7306377

 ??  ?? Nyctixalus pictus (cinnamon tree frog) pictured in the Lower Kinabatang­an Wildlife Sanctuary. Photo credit: Sarah Scriven.
Nyctixalus pictus (cinnamon tree frog) pictured in the Lower Kinabatang­an Wildlife Sanctuary. Photo credit: Sarah Scriven.

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