This blog post is also available in Malay here and Indonesian here.
Martina Harianja discusses the latest research into butterfly assemblages detailing how, alongside colleagues, they recorded over 1200 butterflies across 27 different oil palm plantations. Findings suggest that replanting oil palm and choice of mono or polyculture had relatively few effects on butterflies. However, management for specific features in plantations could benefit butterfly assemblages.
Smallholding oil palm plantations
About 40% of oil palm plantations in Malaysia and Indonesia are managed by smallholders. Therefore, identifying management practices that support local biodiversity within smallholdings could substantially improve conservation for wildlife within oil palm systems.
Being one of the major sources of vegetable oil worldwide, oil palm has expanded at the expense of rainforest in many regions of the tropics. Studies have shown that management decisions can have significant effects on local biodiversity within oil palm plantations (Luke et al., 2020), informing the development of more-sustainable palm oil production.
Unlike industrial-scale plantations, how smallholders manage their farms varies widely, even when located in the same area. Such different approaches include differences in management of the plantation understory, crop choice (monoculture vs polyculture), as well as decisions to do with replanting. Decisions taken on all these aspects of management can affect wildlife within and around plantations. This is because natural vegetation and crops can be used as food sources, nests, or refuges by a wide range of species.
Furthermore, replanting influences microclimatic conditions within oil palm plantations, with a more open canopy often reducing the diversity or composition of local wildlife (Luskin & Potts, 2011; Pashkevich et al., 2021). Despite existing ecological studies within smallholding plantations, including those that assess effects on butterflies, no study has yet investigated the effects of overall management decisions on butterfly populations.
Our study
Our study investigated the effects of fundamental management decisions, particularly the decision to replant and whether to replant with monoculture or polyculture oil palm, within smallholding oil palm plantations in Banting, Selangor, Malaysia. We compared the abundance, species richness, and community composition of butterflies between management types (mature monoculture, immature monoculture, immature polyculture plantations).
We found that habitat structure and complexity differed between management decisions (mature monoculture, immature monoculture, immature polyculture), but that many environmental variables overlapped across decision types. For butterfly populations, we found no significant differences in terms of species richness, density, or assemblage composition between management decisions. However, changes in local environmental conditions, such as an increase of understory vegetation coverage, was associated with a higher abundance of butterflies.
In conclusion, although replanting of oil palm and choice to grow this as a mono or polyculture had relatively few effects on butterflies, management at a local scale, such as maintaining understory vegetation could benefit butterfly assemblages within and around plantations.
Read the full article “How do management decisions impact butterfly assemblages in smallholding oil palm plantations in Peninsular Malaysia?” in Journal of Applied Ecology.
