Abstract
Ecosystem fluxes of isoprene emissions were measured during the majority of the 2011 growing season at the University of Missouri's Baskett Wildlife Research and Education Area in central Missouri, USA (38.7° N, 92.2° W). This broadleaf deciduous forest is typical of forests common in the Ozarks region of the central United States. The goal of the isoprene flux measurements was to test our understanding of the controls on isoprene emission from the hourly to the seasonal timescale using a state-of-the-art emission model, MEGAN (Model of Emissions of Gases and Aerosols from Nature). Isoprene emission rates from the forest were very high with a maximum of 53.3 mg m−2 h−1 (217 nmol m−2 s−1), which to our knowledge exceeds all other reports of canopy-scale isoprene emission. The fluxes showed a clear dependence on the previous temperature and light regimes, which was successfully captured by the existing algorithms in MEGAN. During a period of drought, MEGAN was unable to reproduce the time-dependent response of isoprene emission to water stress. Overall, the performance of MEGAN was robust and could explain 90% of the observed variance in the measured fluxes, but the response of isoprene emission to drought stress is a major source of uncertainty.
Highlights
Atmospheric volatile organic compounds (VOCs) can be from anthropogenic or biogenic sources, and the total VOCs emissions are dominated by biogenic compounds in global scale (Guenther et al, 1995)
The isoprene emission fluxes estimated by MEGAN showed significant diurnal variation with the mean value of 2.4 mg mÀ2 hÀ1 in daytime and the maxima at noon (Fig. 3)
This study indicates that the local constrained MEGAN tends to predict the isoprene emission from the Dinghushan forest reasonably well, with a mean bias of 47.5% and correlation coefficient of 0.7, during fall 2008
Summary
Atmospheric volatile organic compounds (VOCs) can be from anthropogenic or biogenic sources, and the total VOCs emissions are dominated by biogenic compounds in global scale (Guenther et al, 1995). Ozone and secondary organic aerosol) (Carslaw et al, 2000; Carlton et al, 2009) whose impacts may be involved in feedback mechanisms in the Earth's radiation balance (Fuentes and Wang, 1999). It is needed to characterize the emission sources of isoprene and quantify the emission flux reasonably (Fuentes and Wang, 1999). Many studies tried to characterize the sources of isoprene emission and understand emission mechanisms. Foliage temperature and intercepted photosynthetically active radiation (PAR) are reported to exert the greatest environmental influence on isoprene emission (Fuentes et al, 2000).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
