The status and role of ants in oil palm landscapes: knowledge gaps and directions for future research

Ants play crucial roles in terrestrial ecosystems, especially in the tropics where they are abundant and speciose. Growing global demand for oil palm has resulted in extensive deforestation and modifcation of ecosystems. Due to their high abundance, tolerance of some species to change, and the various ecological functions they support, ants represent an important group to study in oil palm landscapes. However, comprehensive research on ants in oil palm systems is severely lacking. Here, we summarise the focus and scope of existing research on this topic and identify future research priorities. We reviewed 74 publications – 80% of which were conducted in Southeast Asia, primarily in Malaysia and Indonesia, and 87% in industrial plantations. This contrasts with the rapidly increasing palm oil production in Africa and the Americas and the importance of smallholder systems globally. We also observed a lack of studies comparing oil palm with other vegetable oil crops, few tests of the efects of alternative oil palm management practices, and – apart from predation – a poor understanding of the role of ants in supporting ecosystem functioning in oil palm landscapes. Studies consistently show that oil palm plantations have lower ant diversity and diferent community compositions compared with forests – including signifcantly more non-native species; yet ants within oil palm landscapes can still be abundant and functionally important. Comparisons with other crops revealed more variable results, but with oil palm supporting higher ant diversity than annual crops like soybean or maize. Our fndings demonstrate that conservation of ant diversity relies on preserving forest habitats for disturbance-intolerant species but indicates that many ant species can survive in oil palm environments, potentially supporting ecosystem processes and yield. To assess whether current fndings are consistent across diferent ecological contexts and to maximise the ant species and functions that can be supported in plantation systems globally, future research should focus on regions other than Southeast Asia, smallholder plantations, and on a wider variety of oil palm management practices and their impacts on ant communities. The importance of ants in oil palm systems should also be highlighted specifcally in best management practice advice given by certifcation bodies, such as the Roundtable on Sustainable Palm Oil, with guidelines being updated as new data emerges.