October 3, 2011 | A team that includes NCAR scientists Anne
Boynard and Alex Guenther has found that the rate at which plant
canopies emit isoprene, a volatile organic compound, is
influenced by circadian rhythms. The discovery has the potential
to lead to more accurate predictions of ground-level ozone,
which is harmful to human health. For the study, the researchers
made measurements of isoprene in Malaysia above both tropical
rain forest and oil palm plantations. They observed for the
first time ever a circadian (24-hour) rhythm operating in
concert across the entire tree canopy, especially in the palm
plantation. The finding changes how scientists estimate isoprene
emissions from plants, as both the palm plantations and rain
forest emit less isoprene than shown by computer models of
emissions. This has implications for ground-level ozone, which
forms when volatile organic compounds such as isoprene react
with nitrogen oxides from automobiles and industry. The
researchers incorporated the circadian pattern