Abstract ID: 8

Drought impacts on carbon cycling in an Amazonian rainforest:

The Amazon rainforest plays a key role in the global climate system, because each year it absorbs a quantity of the greenhouse gas carbon dioxide (CO2) equivalent to the emissions of the entire European Union. However, some computer climate models predict that an increased frequency and severity of drought events in the Amazon region may cause large areas of the forest to become a net source of CO2 over the next hundred years. We know little about how the Amazon ecosystem will respond to drought, and what the implications could be for the release of CO2 into the atmosphere. Our research aimed to address this gap in our knowledge by quantifying the amount of carbon stored in different components of an Amazonian rain forest, and the pattern of carbon transfer between components. The effects of drought were inferred by comparing a one hectare plot where rainfall had been excluded for four years with a similar, but unmodified, control plot. The results indicate that the forest, at least in this region of the Amazon, is remarkably resilient to drought. While there was a decrease in CO2 uptake by the trees on the droughted plot relative to the control, this was outweighed by a simultaneous decline in CO2 emerging from the forest soil, with the result that the droughted forest was actually estimated to be a net carbon sink during the year of measurement. These results advance our understanding of the interactions between climate and forests, and should improve current estimates of future atmospheric CO2 levels.

Session:  Carbon - The role of seasonality in carbon and water balance.

Presentation Type:  Oral