Recently, Eva Pfannerstill and her team wanted to find out how Amazonian plants react to ecological stresses, such as heat and drought. They wondered if they release more VOCs in such a situation. To do that, they compared data from November 2012 and 2015. 2012 was a pretty “normal” year without any significant temperature or precipitation anomaly. 2015, on the other hand, was influenced by a particularly strong El Nino. It brought extremely hot temperatures and severe drought to the region. However, the scientists were surprised to find that overall emissions were pretty much the same in the two years. But they did discover a different distribution over the day. In the El Nino year, the plants emitted most VOCs during the sunset hour. In the “normal” year the peak was at noon. They attribute this unexpected discovery to more turbulent winds associated with the high temperatures. These transport the VOCs higher, above the forest canopy to the instrument.
The study was published in Frontiers in Forest and Global Change, Issue 18 under the title “Total OH Reactivity Changes Over the Amazon Rainforest During an El Niño Event” by Pfannerstill et al. and is available Open Access.