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Rapid leaf development drives the seasonal pattern of volatile organic compound (VOC) fluxes in a 'coppiced' bioenergy poplar plantation

Journal Contribution - Journal Article

Leaves of fast-growing, woody bioenergy crops often emit volatile organic compounds (VOC). Some reactive VOC (especially isoprene) play a key role in climate forcing and may negatively affect local air quality. We monitored the seasonal exchange of VOC using the eddy covariance technique in a coppiced' poplar plantation. The complex interactions of VOC fluxes with climatic and physiological variables were also explored by using an artificial neural network (Self Organizing Map). Isoprene and methanol were the most abundant VOC emitted by the plantation. Rapid development of the canopy (and thus of the leaf area index, LAI) was associated with high methanol emissions and high rates of gross primary production (GPP) since the beginning of the growing season, while the onset of isoprene emission was delayed. The highest emissions of isoprene, and of isoprene photo-oxidation products (Methyl Vinyl Ketone and Methacrolein, i(ox)), occurred on the hottest and sunniest days, when GPP and evapotranspiration were highest, and formaldehyde was significantly deposited. Canopy senescence enhanced the exchange of oxygenated VOC. The accuracy of methanol and isoprene emission simulations with the Model of Emissions of Gases and Aerosols from Nature increased by applying a function to modify their basal emission factors, accounting for seasonality of GPP or LAI. center dot Some reactive volatile organic compounds (VOC) (especially isoprene) emitted in the atmosphere from leaves of widespread fast-growing woody bioenergy crops play a key role in climate forcing and local air quality. center dot Eddy covariance VOC emission and deposition fluxes were monitored in a coppiced' poplar plantation during an entire growing season, and their complex interactions with climatic and physiological variables also including canopy structural traits were explored by using the Self-organizing Map. center dot Rapid development of a canopy (and thus of leaf area index, LAI) was associated with high methanol emissions and high rates of gross primary production (GPP) since the beginning of the growing season, while the onset of isoprene emission was delayed. center dot The highest emissions of isoprene, and of isoprene photooxidation products (methyl vinyl ketone and methacrolein, iox) occurred on the hottest and sunniest days, when also GPP and evapotranspiration were highest and formaldehyde was significantly deposited. center dot The accuracy of methanol and isoprene emission simulations with the MEGAN model increased by applying a function to modify their basal emission factors, accounting for seasonality of GPP or LAI.
Journal: Plant, Cell & Environment
ISSN: 0140-7791
Volume: 39
Pages: 539 - 555
Publication year:2016
Keywords:Plant sciences