A systematic map of within-plantation oil palm management practices reveals a rapidly growing but patchy evidence base

Although oil palm expansion has had severe environmental impacts, oil palm also has the highest yield per hectare of any vegetable oil crop. Compared to many other crops, it has the potential to support high complexity habitats, with minimal chemical input, and relatively high levels of biodiversity and ecosystem functioning. However, there has been little synthesis of available research on oil palm management strategies to support delivery of more sustainable cultivation. In this paper, we provide a systematic map compiling all available evidence assessing within-plantation oil palm management practices at the cultivation stage, with a focus on practices that affect biodiversity and environmental processes. Using approaches adapted from systematic review protocols, we catalogued oil palm management publications to provide details of geographic location, year, interventions tested (i.e. agricultural practices), targeted outcomes of interventions, co-occurrences between different interventions and outcomes (including multiple outcomes), and study design. Most studies were conducted in Southeast Asia, with fewer studies conducted in South America or Africa. Twenty-six interventions were observed in the literature, across six categories: soil, understory, within-crop, landscape-level, replanting, and mixed/multiple interventions. The most common interventions tested were landscape-scale interventions, such as maintaining forest fragments/buffer zones, whereas interventions involved in replanting were the least researched. Eight outcomes were considered: soil fertility, soil erosion, water quality and availability, pest control, replanting, maintenance of biodiversity and areas of high conservation value, and reducing air pollution and greenhouse gas emissions. Studies researching biodiversity were the most common, whereas comparatively few studies considered replanting and reducing emissions. Most primary studies were observational, with experimental studies being rarer, especially in biodiversity research. We match our findings to the Roundtable on Sustainable Palm Oil’s environmental sustainability criteria to illustrate how policy-makers and producers may use our map to access evidence supporting cultivation-stage oil palm sustainability management. This study provides valuable information to inform best management practices and direction for necessary future research.