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| Titel |
Extreme events in gross primary production: a characterization across continents |
| VerfasserIn |
J. Zscheischler, M. Reichstein, S. Harmeling, A. Rammig, E. Tomelleri, M. D. Mahecha |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 11 ; Nr. 11, no. 11 (2014-06-04), S.2909-2924 |
| Datensatznummer |
250117444
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| Publikation (Nr.) |
 copernicus.org/bg-11-2909-2014.pdf |
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| Zusammenfassung |
| Climate extremes can affect the functioning of terrestrial ecosystems, for
instance via a reduction of the photosynthetic capacity or alterations of
respiratory processes. Yet the dominant regional and seasonal effects of
hydrometeorological extremes are still not well documented and in the focus
of this paper. Specifically, we quantify and characterize the role of large
spatiotemporal extreme events in gross primary production (GPP) as triggers
of continental anomalies. We also investigate seasonal dynamics of extreme
impacts on continental GPP anomalies. We find that the 50 largest positive
extremes (i.e., statistically unusual increases in carbon uptake rates) and
negative extremes (i.e., statistically unusual decreases in carbon uptake
rates) on each continent can explain most of the continental variation in
GPP, which is in line with previous results obtained at the global scale. We
show that negative extremes are larger than positive ones and demonstrate
that this asymmetry is particularly strong in South America and Europe. Our
analysis indicates that the overall impacts and the spatial extents of GPP
extremes are power-law distributed with exponents that vary little across
continents. Moreover, we show that on all continents and for all data sets
the spatial extents play a more important role for the overall impact of GPP
extremes compared to the durations or maximal GPP. An analysis of possible
causes across continents indicates that most negative extremes in GPP can be
attributed clearly to water scarcity, whereas extreme temperatures play a
secondary role. However, for Europe, South America and Oceania we also
identify fire as an important driver. Our findings are consistent with remote
sensing products. An independent validation against a literature survey on
specific extreme events supports our results to a large extent. |
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