The majority of OP standing biomass is stored as aboveground biomass (AGB) constituting 84% of biomass stocks, with the reminder (16%) stored as belowground biomass (BGB) consequently, efforts here focus primarily on AGB quantification 11, 12, 13. In part, uncertainty is attributed to a scarcity of literature which addresses the rate at which OP on peat accumulates carbon in biomass over time 6, 7, 8, 9, 10. The carbon emissions from the oxidation of soil organic matter following the conversion of peat swamp forest to OP are relatively well known, yet the net carbon emission of peat swamp forest conversion to OP across the life of a plantation remains poorly constrained 3, 4, 5, 6. The rapid expansion of OP in Insular Southeast Asia during the last quarter decade has resulted in the conversion of 3.1 Mha of tropical peatlands 2. Global demand for palm oil has risen such that the land area supporting oil palm (OP, Elaeis guineensis) plantations has increased to ~25 Mha globally making OP the 12 th largest edible crop by land area 1.
Validation of the allometries defined and expansion of non-destructive inventories across alternative plantations and age classes on peat would further strengthen our understanding of peat OP AGB accumulation rates. High inter-palm and inter-block AGB variability was observed in mature classes as a result of variations in palm leaning and mortality. Aboveground biomass stocks on peat accumulated at ~6.39 ± 1.12 Mg ha −1 per year in the first 12 years after planting, increasing to ~7.99 ± 0.95 Mg ha −1 yr −1 when a ‘perfect’ plantation was modelled.
Allometries are used to upscale AGB estimates to the plantation block-level. Peat specific allometric equations for palm (R 2 = 0.92) and frond biomass are developed and contrasted to existing allometries for OP on mineral soils. We quantify the AGB stocks of an OP plantation on drained peat in Malaysia from 3 to 12 years after planting using destructive harvests supported by non-destructive surveys of a further 902 palms. However, estimates of net carbon flux from biomass changes require accurate estimates of the above ground biomass (AGB) accumulation rate of OP on peat. The recent expansion of oil palm (OP, Elaeis guineensis) plantations into tropical forest peatlands has resulted in ecosystem carbon emissions.