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Title: Leaf phenology as one important driver of seasonal changes in isoprene emission in central Amazonia

Isoprene fluxes vary seasonally with changes in environmental factors (e.g., solar radiation and temperature) and biological factors (e.g., leaf phenology). However, our understanding of seasonal patterns of isoprene fluxes and associated mechanistic controls are still limited, especially in Amazonian evergreen forests. Here in this article, we aim to connect intensive, field-based measurements of canopy isoprene flux over a central Amazonian evergreen forest with meteorological observations and with tower-camera leaf phenology to improve understanding of patterns and causes of isoprene flux seasonality. Our results demonstrate that the highest isoprene emissions are observed during the dry and dry-to-wet transition seasons, whereas the lowest emissions were found during the wet-to-dry transition season. Our results also indicate that light and temperature can not totally explain the isoprene flux seasonality. Instead, the camera-derived leaf area index (LAI) of recently mature leaf-age class (e.g. leaf ages of 3–5 months) exhibits the highest correlation with observed isoprene flux seasonality (R 2=0.59, p<0.05). Attempting to better represent leaf phenology in the Model of Emissions of Gases and Aerosols from Nature (MEGAN 2.1), we improved the leaf age algorithm utilizing results from the camera-derived leaf phenology that provided LAI categorized in three different leaf ages. The model results showmore » that the observations of age-dependent isoprene emission capacity, in conjunction with camera-derived leaf age demography, significantly improved simulations in terms of seasonal variations of isoprene fluxes (R 2=0.52, p<0.05). This study highlights the importance of accounting for differences in isoprene emission capacity across canopy leaf age classes and of identifying forest adaptive mechanisms that underlie seasonal variation of isoprene emissions in Amazonia.« less
ORCiD logo [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [2] ; ORCiD logo [6] ;  [1] ;  [1] ;  [1] ;  [7] ; ORCiD logo [4] ;  [8] ;  [9] ; ORCiD logo [10] ;  [11] ;  [12]
  1. National Inst. for Amazonian Research (INPA), Manaus (Brazil). Dept. of Environmental Dynamics
  2. Federal Univ. of West Para (UFOPA) Santarem (Brazil). Inst. of Engineering and Geoscience
  3. 2B Technologies, Inc., Boulder, CO (United States)
  4. Univ. of California, Irvine, CA (United States). Dept. of Earth System Science
  5. National Inst. for Energy and Nuclear Research (IPEN), Sao Paulo (Brazil)
  6. Federal Univ. of Para, Belem, PA (Brazil). Dept. of Meteorology, Geosciences Inst.
  7. State Univ. of Amazonas (UEA), Manaus, AM (Brazil). Meteorology Dept.
  8. Royal Belgian Inst. for Space Aeronomy, Brussels (Belgium)
  9. Univ. Nacional Autonoma de Mexico (UNAM), Mexico City (Mexico). Centro de Ciencias de la Atmosfera
  10. Brookhaven National Lab. (BNL), Upton, NY (United States). Dept. of Environmental and Climate Sciences
  11. Univ. of Arizona, Tucson, AZ (United States). Ecology and Evolutionary Biology Dept.
  12. National Inst. for Spatial Research, Cachoeira Paulista, SP (Brazil)
Publication Date:
Report Number(s):
Journal ID: ISSN 1810-6285
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Biogeosciences Discussions (Online)
Additional Journal Information:
Journal Name: Biogeosciences Discussions (Online); Journal ID: ISSN 1810-6285
European Geosciences Union
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
OSTI Identifier: