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| Titel |
Biosphere-atmosphere exchange of CO2 in relation to climate: a cross-biome analysis across multiple time scales |
| VerfasserIn |
P. C. Stoy, A. D. Richardson, D. D. Baldocchi, G. G. Katul, J. Stanovick, M. D. Mahecha, M. Reichstein, M. Detto, B. E. Law, G. Wohlfahrt, N. Arriga, J. Campos, J. H. McCaughey, L. Montagnani, Paw U. K. T., S. Sevanto, M. Williams |
| 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 ; 6, no. 10 ; Nr. 6, no. 10 (2009-10-30), S.2297-2312 |
| Datensatznummer |
250004046
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| Publikation (Nr.) |
 copernicus.org/bg-6-2297-2009.pdf |
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| Zusammenfassung |
| The net ecosystem exchange of CO2 (NEE) varies at time scales from seconds
to years and longer via the response of its components, gross ecosystem
productivity (GEP) and ecosystem respiration (RE), to physical and biological
drivers. Quantifying the relationship between flux and climate at multiple
time scales is necessary for a comprehensive understanding of the role of
climate in the terrestrial carbon cycle. Orthonormal wavelet transformation
(OWT) can quantify the strength of the interactions between gappy eddy
covariance flux and micrometeorological measurements at multiple frequencies
while expressing time series variance in few energetic wavelet coefficients,
offering a low-dimensional view of the response of terrestrial carbon flux to
climatic variability. The variability of NEE, GEP and RE, and their
co-variability with dominant climatic drivers, are explored with nearly one
thousand site-years of data from the FLUXNET global dataset consisting of 253
eddy covariance research sites. The NEE and GEP wavelet spectra were similar
among plant functional types (PFT) at weekly and shorter time scales, but
significant divergence appeared among PFT at the biweekly and longer time
scales, at which NEE and GEP were relatively less variable than climate. The
RE spectra rarely differed among PFT across time scales as expected. On
average, RE spectra had greater low frequency (monthly to interannual)
variability than NEE, GEP and climate. CANOAK ecosystem model simulations
demonstrate that "multi-annual" spectral peaks in flux may emerge at low
(4+ years) time scales. Biological responses to climate and other internal
system dynamics, rather than direct ecosystem response to climate, provide
the likely explanation for observed multi-annual variability, but data
records must be lengthened and measurements of ecosystem state must be made,
and made available, to disentangle the mechanisms responsible for low
frequency patterns in ecosystem CO2 exchange. |
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