The atmospheric potential of biogenic volatile organic compoundsfrom needles of white pine (Pinus strobus) in Northern Michigan
The key role that biogenic volatile organic compounds(BVOC) play in atmospheric chemistry requires a detailedunderstanding of how BVOC concentrations will beaffected by environmental change. Large-scale screening ofBVOC emissions from whole forest ecosystems is difficultwith enclosure methods. Leaf composition of BVOC, as asurrogate for direct emissions, can more easily reflect thedistribution of BVOC compounds in a forest. In this study,BVOC composition in needles of 92 white pine trees (Pinusstrobus), which are becoming a large part of Midwest forests,are tracked for three summers at the University of MichiganBiological Station (UMBS). a-Pinene, the dominant terpenein all samples, accounts for 30–50%of all terpenes on a molebasis. The most abundant sesquiterpenoid was a C15 alcoholidentified as germacrene D-4-ol. The relationship betweenlimonene and total other monoterpenes shows two distincttrends in the population of these forests. About 14%(n=13)of the trees showed high levels of limonene (up to 36% ofthe total BVOC) in the same trees every year. Assumingthat needle concentrations scale with emission rate, we estimatethat hydroxyl radical reactivity due to reaction withmonoterpenes from white pine increases approximately 6%at UMBS when these elevated concentrations are included.We suggest that chemotypic variation within forests has thepotential to affect atmospheric chemistry and that large-scalescreening of BVOC can be used to study the importance ofBVOC variation.