Transport in xylem sap affects the emissions of acetaldehyde from Scots pine stem

Water-soluble volatile organic compounds may be transported within tree stem dissolved in xylem sap, and transport in xylem sap could affect their emissions both from foliage and stem. One of the water-soluble VOCs is acetaldehyde, the production of which is increased in roots and soil when the amount of water in soil is high and oxygen availability is locally limited. Using acetaldehyde flux measurements from two stem heights of Scots pine, we tested whether the soil moisture affected the emissions of acetaldehyde from the stem and whether the transport of acetaldehyde could be detected in the lag time between a high soil moisture peak and increased acetaldehyde emissions. We detected small lagged correlations between acetaldehyde emissions from stem and soil water potential, the lag time increasing with measurement height. These results suggest that the transport of acetaldehyde in xylem sap does affect acetaldehyde emissions from the stem, and their emission dynamics could potentially be used to understand the transport and emissions of other water-soluble compounds, too.