El Niño–Southern Oscillation (ENSO) event reduces CO<sub>2</sub> uptake of an Indonesian oil palm plantation

Abstract

Abstract. The El Niño–Southern Oscillation (ENSO) in 2015 was one of the strongest observed in almost 20 years and set the stage for a severe drought and the emergence of widespread fires and related smoke emission over large parts of Southeast Asia. In the tropical lowlands of Sumatra, which were heavily affected by the drought and haze, large areas of tropical rainforest have been converted into oil palm (Elaeis guineensis Jacq.) plantations during the past decades. In this study, we investigate the impact of drought and smoke haze on the net ecosystem CO2 exchange, evapotranspiration, yield and surface energy budget in a commercial oil palm plantation in Jambi province (Sumatra, Indonesia) by using micrometeorological measurements, the eddy covariance method, yield data and a multiple linear regression model (MLRM). With the MLRM we identify the contribution of meteorological and environmental parameters to the net ecosystem CO2 exchange. During the initial part of the drought, when incoming shortwave radiation was elevated, net CO2 uptake increased by 50 % despite a decrease in upper-layer soil moisture by 35 %, an increase in air temperature by 10 % and a tripling of atmospheric vapour pressure deficit. Emerging smoke haze decreased incoming solar radiation by 35 % compared to non-drought conditions and diffuse radiation almost became the sole shortwave radiation flux for 2 months, resulting in a strong decrease in net CO2 uptake by 86 %. Haze conditions resulted in a complete pause of oil palm net carbon accumulation for about 1.5 months and contributed to a decline in oil palm yield by 35 %. With respect to a projected pronounced drying trend over the western Pacific during a future El Niño, our model showed that an increase in drought may stimulate net CO2 uptake, while more severe smoke haze, in combination with drought, can lead to pronounced losses in productivity and net CO2 uptake, highlighting the importance of fire prevention.

Measured greenhouse gas budgets challenge emission savings from palm-oil biodiesel

“…Due to the large variability of the fluxes, we did not find significant differences with mineral soils in the temporal datasets (P = 0.098 and 0.735 for N 2 O and CH 4 , respectively), but the differences in means were significant (P < 0.001; Mann-Whitney U test; Supplementary Table 3). We observed generally low GHG emissions during dry seasons (e.g., July to October 2015, when intense drought occurred due to a strong El Nino event 28,40,41 ; Supplementary Fig. 2), and pulses of soil N 2 O emission following fertilization.…”

“…the 12-year-old plantation was a C source with considerable interannual variability (52-240 gC m −2 yr −1 ), possibly caused by the strong El Nino year during our measurement period 28,40,41 . The 1-year-old plantation, not having produced fruits yet, had no C exported via harvest, and NEP thus equalled NEE.…”

Short‐ and long‐term carbon emissions from oil palm plantations converted from logged tropical peat swamp forest

“…This dip in activity appears to have recovered at some point during our missing data period between then and September 2019. Stiegler et al (2019) showed that drought conditions resulting from an El Nino‐Southern Oscillation (ENSO) event in 2015 led to reduced CO 2 uptake into their study site at an Indonesian oil palm plantation. This might suggest that another ENSO event in the region, recorded between September 2018 and June 2019 (https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/el-nino-la-nina), could be linked to our indication of a drop‐off in photosynthetic activity.…”

Implication of land use change to biogeophysical and biogeochemical processes in Jambi, Indonesia: Analysed using CLM5

“…Sensible heat fluxes will dominant rather than latent heat fluxes. Smoke absorbed and scattered solar radiation lead to decrease in incoming solar radiation (Stiegler et al 2019). Decreasing downward solar radiation along with drought and heat stress triggered partial stomata closure that reduced evapotranspiration and latent heat fluxes (Stiegler et al 2019).…”