Outburst of senescence-related VOC emissions from a bioenergy poplar plantation.

Leaf senescence is a catabolic process that emits volatile organic compounds (VOCs). In densely planted monocultures these VOC emissions occur in outbursts that might be relevant for the local air quality since these VOCs are typically oxygenated. The VOC emissions of a high-density poplar (Populus) bioenergy plantation were monitored along with meteorological parameters, CO2 and H2O exchanges, canopy greenness, and leaf area index during the second half of the year 2015. The emissions of 25 VOCs peaked at the beginning of September, coinciding with the onset of senescence. Together these VOC emissions amounted to a total of 2.85 mmol m-2, translated into 98.3 mg C m-2. The emission peak was mainly composed of oxygenated VOCs as methanol, acetic acid, and lipoxygenase products that are all typical for catabolic processes. So, the senescence process of the poplar plantation was very well reflected in the peak of VOC emissions.