What is the Impact of Oil Palm on Arthropods (and what can be done to mitigate it)?
Oil palm in West Africa
When we think about oil palm cultivation, Southeast Asia often comes to mind. The industry’s rapid expansion there has been well-researched, particularly its effects on biodiversity and the environment. But oil palm cultivation is now rapidly expanding West Africa, where it grows naturally and has been traditionally harvested for centuries. Unlike the industrial-scale plantations that are common in Southeast Asia, many West African farmers cultivate oil palm alongside subsistence crops like cassava, rice, and banana in what’s known locally as ‘country palm’ farms. These small-scale farms stand in stark contrast to the industrial plantations which are now increasing across the region, where foreign companies are clearing rainforests to establish oil palm monocultures using intensive agricultural techniques.
While research on oil palm’s ecological impact in Southeast Asia is extensive, much less is known about its effects in West Africa. That’s why, as part of the Sustainable Oil Palm in West Africa (SOPWA) Project, we set out to study the biodiversity of ground-dwelling arthropods (insects, spiders, and similar creatures) across three different systems in Liberia: natural rainforest, traditional country palm farms, and industrial oil palm plantations.
Traditional and industrial oil palm farming impacts arthropod biodiversity in Liberia
Our findings were fascinating. While the total number of arthropods didn’t vary significantly across our study systems, the composition of these communities did. We saw shifts in the abundance of spiders (Araneae), springtails (Collembola), earwigs (Dermaptera), and flies (Diptera). We conducted species-level analyses on spiders, owing to their key roles as predators within tropical agricultural systems. Our spider results indicated that country palm supported the greatest number of spider individuals and species, and that all systems supported distinct spider assemblages.
Why is this important for oil palm cultivation?
Biodiversity isn’t just important for conservation – it directly affects agriculture. Spiders, for instance, prey on insect pests like slug moth caterpillars and bagworms, which can significantly damage oil palm yields. Maintaining high abundances of spiders within industrial oil palm plantations may lead to increased predation of pests, and potentially higher crop yields. Springtails and earwigs play a key role in decomposition and are prey for other arthropods, whilst flies are pollinators and decomposers. Therefore, the differences in arthropod biodiversity that we found across our study systems are not only important for conservation but also oil palm yields, owing to the vital ecosystem functions that many arthropod species provide.
How can we protect arthropods in oil palm systems?
To conserve arthropods in West African oil palm plantations, a few management strategies can be considered:
- Maintain forest fragments near plantations:Preserving patches of natural forest within or around oil palm farms can provide refuge for beneficial species, enhancing biodiversity and ecosystem services (e.g., pest control, pollination).
- Reduce herbicide use:Allowing understory vegetation to grow can create habitat complexity, supporting a wider range of arthropods.
- Diversify plantations:Integrating polyculture systems or tree islands within oil palm farms can improve species richness by increasing vegetation diversity.
While these approaches have been studied in Southeast Asia, their effectiveness in West Africa is still uncertain. More research is needed to determine how best to balance crop yields with conservation in this unique context. Identifying such strategies is a key component to ensuring the long-term sustainability of the West African oil palm industry.
More information:
https://www.sciencedirect.com/science/article/pii/S0048969724019934
https://www.sciencedirect.com/science/article/pii/S0167880925001586