Tropical rainforest landscapes are threatened by the industrial agricultural expansion, which leads to forest fragmentation and habitat loss. The remaining wildlife is found in low quality and fragmented habitats, leaving numerous species at risk of extinction. Some species even modify their feeding behaviors to survive by relying on crops as their main sources of food. Industrial oil palm cultivation is the main driver of biodiversity loss in Southeast Asian. It is a major concern for monoculture oil palm plantations characterized by low-quality, simplified, and species-poor habitats. Lots of studies on the impacts of oil palm agriculture have been carried out on birds, amphibians, reptiles, and rodents, yet little attention has been given to primate species, especially monkeys that are often found utilizing these plantations.
Previous studies have indicated that industrial oil palm plantations support lower levels of biodiversity than the smallholding and native forest. However, biodiversity conservation on oil palm production landscapes can be improved if major oil palm producers are ready to transform the way they grow and manage their crops. Consumer pressure could encourage major oil palm producers to change their farming practices, but this pressure must have a broader reach than is currently the case.
In our study, we examined the effects of industrial oil palm expansion on long-tailed macaque, M. fascicularis, populations. We contrasted differences in group size between industrial oil palm plantation and smallholdings, logged forest, and unlogged forest.
The long-tailed macaque (LTM) is a species commonly known as an ecological generalist that is geographically widespread, characterized by an omnivorous diet, and is able to thrive in human-modified landscapes. This macaque species inhabits in a wide range of habitat types from undisturbed forests to highly human-disturbed areas such as urban and agricultural landscapes. LTM is also a well-known pest animal that raids crops on farmlands and harasses public visitors in recreational as well as housing areas.
How serious are the impacts brought on by industrial oil palm expansion on biodiversity, particularly the population of the common species such as the long-tailed macaque? Limited studies on LTM in Malaysia have led to the current study that examines the effects of industrial oil palm expansion on LTM population. Population surveys on LTM were conducted at (1) an industrial oil palm plantation (1690 ha) in Johor state, (2) an oil palm smallholding (7810 ha), and (3) a logged forest (1176 ha) in Selangor state, Malaysia. Farmers operated oil palm smallholding through either monoculture or polyculture with oil palm trees integrated with cash crops such as coconut, banana, tapioca, and other fruit trees. We also compared the data to a baseline population survey of unlogged forests from a previous study at the Krau Wildlife Reserve, Pahang.
A key result from this study was less LTM found at the industrial oil palm plantation than that at the smallholding. This study also found more LTM in the unlogged and logged forests compared to the industrial oil palm plantation, but, surprisingly, in the smallholding, the number of LTM surpassed the unlogged forest. A possible explanation for the results is a lower habitat quality of industrial oil palm plantation with homogeneous vegetation type and lower food availability. Monoculture practice resulted in homogeneous vegetation, primarily Elaeis guineensis, also limiting the choice of sleeping sites for LTM. Anthropogenic intervention (e.g. growers have set up traps or used firecrackers to prevent crop raiding by LTM) might also contribute to the low number of LTM in the industrial oil palm plantation. LTMs are thriving in the logged forest as it can provide food resources such as human waste found in the surrounding local residential areas. In contrast, the thriving LTM populations in the smallholdings are attributed to a number of factors, including the diversity and density of trees and the presence of native flora in the understory.
In conclusion, LTMs are more abundant in diverse, heterogeneous, and resource-rich habitats such as oil palm smallholding, logged forests, and unlogged forests. The detrimental impacts brought by industrial oil palm plantation are more severe than oil palm smallholding as it even affecting the common macaque species. Hence, smallholding production systems in which palm oil is mixed with other crops should be considered by retailers and consumers who are keen to promote sustainable palm oil production. Industrial oil palm plantation should be minimized, as it causes adverse impacts on biodiversity including the common species, the long-tailed macaque. Major plantation companies should be required to make their existing production landscapes more compatible with biodiversity conservation. Agroforestry practices can be applied in industrial oil palm plantations to minimize wildlife-human conflicts by providing areas planted with fruit trees for LTMs.
These findings are described in the article entitled The effect of oil palm agricultural expansion on group size of long-tailed macaques (Macaca fascicularis) in Peninsular Malaysia, recently published in the journal Mammalian Biology.
Reference:
- Tee, S. L., Solihhin, A., Juffiry, S. A., Putra, T. R., Lechner, A. M., & Azhar, B. (2019). The effect of oil palm agricultural expansion on group size of long-tailed macaques (Macaca fascicularis) in Peninsular Malaysia. Mammalian Biology, 94, 48-53.