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| Titel |
Biotic stress accelerates formation of climate-relevant aerosols in boreal forests |
| VerfasserIn |
J. Joutsensaari, P. Yli-Pirilä, H. Korhonen, A. Arola, J. D. Blande, J. Heijari, M. Kivimäenpää, S. Mikkonen, L. Hao, P. Miettinen, P. Lyytikäinen-Saarenmaa, C. L. Faiola, A. Laaksonen, J. K. Holopainen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 21 ; Nr. 15, no. 21 (2015-11-02), S.12139-12157 |
| Datensatznummer |
250120135
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| Publikation (Nr.) |
 copernicus.org/acp-15-12139-2015.pdf |
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| Zusammenfassung |
| Boreal forests are a major source of climate-relevant biogenic secondary
organic aerosols (SOAs) and will be greatly influenced by increasing
temperature. Global warming is predicted to not only increase emissions of reactive
biogenic volatile organic compounds (BVOCs) from vegetation directly but
also induce large-scale insect outbreaks, which significantly increase
emissions of reactive BVOCs. Thus, climate change factors could substantially
accelerate the formation of biogenic SOAs in the troposphere. In this study,
we have combined results from field and laboratory experiments, satellite
observations and global-scale modelling in order to evaluate the effects of
insect herbivory and large-scale outbreaks on SOA formation and the Earth's
climate. Field measurements demonstrated 11-fold and 20-fold increases in
monoterpene and sesquiterpene emissions respectively from damaged trees
during a pine sawfly (Neodiprion sertifer) outbreak in eastern Finland. Laboratory chamber
experiments showed that feeding by pine weevils (Hylobius abietis) increased VOC emissions
from Scots pine and Norway spruce seedlings by 10–50 fold, resulting in
200–1000-fold increases in SOA masses formed via ozonolysis. The influence
of insect damage on aerosol concentrations in boreal forests was studied
with a global chemical transport model GLOMAP and MODIS satellite
observations. Global-scale modelling was performed using a 10-fold increase
in monoterpene emission rates and assuming 10 % of the boreal forest area
was experiencing outbreak. Results showed a clear increase in total
particulate mass (local max. 480 %) and cloud condensation nuclei
concentrations (45 %). Satellite observations indicated a 2-fold
increase in aerosol optical depth over western Canada's pine forests
in August during a bark beetle outbreak. These results suggest that more
frequent insect outbreaks in a warming climate could result in substantial
increase in biogenic SOA formation in the boreal zone and, thus, affect both
aerosol direct and indirect forcing of climate at regional scales. The
effect of insect outbreaks on VOC emissions and SOA formation should be
considered in future climate predictions. |
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