Drought stress and tree size determine stem CO2 efflux in a tropical forest

What is it about?

Woody stems make up a large proportion of the biomass in tropical rainforests. However the CO2 emitted from tree stems, especially during climate anomalies such as drought events, is poorly studied. We measure the CO2 emitted from tree stems at the worlds longest running tropical forest drought experiment. Using these data we are able to demonstrate that droughted trees release 27% more CO2 than non-droughted trees during the wet season. This process is however driven by elevated CO2 release from tree in smaller diameter classes. Our findings indicate that under future climate change scenarios of elevated drought increases in CO2 released from stems may augment carbon losses, weakening or potentially reversing the tropical forest carbon sink.

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