Effects Of The 2015–2016 El Niño Event On Energy And CO2 Fluxes Of A Tropical Rainforest In Central Sulawesi, Indonesia

Abstract

The influence of the very strong 2015–16 El Niño event on local and regional meteorological conditions, as well as on energy and CO2 fluxes in a mountainous primary tropical rainforest was investigated using ERA-Interim reanalysis data as well as meteorological and eddy covariance flux measurements from Central Sulawesi in Indonesia. The El Niño event led to a strong increase of incoming monthly solar radiation and air temperature, simultaneously with the increasing Niño4 index. Monthly precipitation first strongly decreased and then increased reaching a maximum in 3–4 months after El Niño culmination. Ecosystem respiration increased while gross primary production showed only a weak response to the El Niño event resulting in a positive anomaly of net ecosystem CO2 exchange (reduced CO2 uptake). The changes of key meteorological parameters and fluxes caused by the strong El Niño event of 2015–16 differed from the effects of moderate El Niño events observed during the period 2003-2008, where net ecosystem CO2 exchange remained largely unaffected. In contrast to earlier moderate El Niño events, the strong El Niño 2015–16 affected mostly the air temperature resulting in a weakening of the net carbon sink at the rainforest site in Central Sulawesi, Indonesia.

Keywords

• el niño southern oscillation
• niño4
• tropical rainforest
• eddy covariance flux measurements
• energy and co2 fluxes