Soil CO2 emissions and net primary production of an oil palm plantation established on tropical peat

The C dynamics of a young (7 years old) smallholder oil palm plantation on peat soil in South Kalimantan (Indonesia) was investigated by directly assessing soil carbon dioxide (CO2) emissions and C sequestration as net primary production (NPP) over a period of 19 months, from September 2018 to March 2020. Soil CO2 efflux was measured monthly using a closed chamber system in ‘near (1m)’ and ‘far (3m)’ positions relative to tree bases, in order to measure total soil respiration (SR) and peat decomposition (PD), respectively. Simultaneously, litter (frond) decomposition (LD) was measured using a litter bag method. NPP was calculated as the sum of above-ground and below-ground biomass production. The C fluxes via SR, PD and LD were estimated to be 23.1 ± 6.13, 15.4 ± 4.37 (mean ± SD) and 0.38 Mg ha-1 yr-1, respectively. NPP (as C) was estimated to be 1090 g m-2 yr-1. NPP was low, mostly due to immaturity of the plantation. Heterotrophic respiration (HR) (= PD + LD) was 15.8 Mg ha-1 yr 1, resulting in the plantation acting as a net C source of 4.9 Mg ha-1 yr-1 (= NPP - HR).