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| Titel |
Process-based estimates of terrestrial ecosystem isoprene emissions: incorporating the effects of a direct CO2-isoprene interaction |
| VerfasserIn |
A. Arneth, Ü. Niinemets, S. Pressley, J. Bäck, P. Hari, T. Karl, S. Noe, I. C. Prentice, D. Serça, T. Hickler, A. Wolf, B. Smith |
| 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 ; 7, no. 1 ; Nr. 7, no. 1 (2007-01-10), S.31-53 |
| Datensatznummer |
250004343
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| Publikation (Nr.) |
 copernicus.org/acp-7-31-2007.pdf |
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| Zusammenfassung |
In recent years evidence has emerged that the amount of isoprene emitted
from a leaf is affected by the CO2 growth environment. Many – though not
all – laboratory experiments indicate that emissions increase significantly
at below-ambient CO2 concentrations and decrease when concentrations
are raised to above-ambient. A small number of process-based leaf isoprene
emission models can reproduce this CO2 stimulation and inhibition.
These models are briefly reviewed, and their performance in standard
conditions compared with each other and to an empirical algorithm. One of
the models was judged particularly useful for incorporation into a dynamic
vegetation model framework, LPJ-GUESS, yielding a tool that allows the
interactive effects of climate and increasing CO2 concentration on
vegetation distribution, productivity, and leaf and ecosystem isoprene
emissions to be explored. The coupled vegetation dynamics-isoprene model is
described and used here in a mode particularly suited for the ecosystem
scale, but it can be employed at the global level as well.
Annual and/or daily isoprene emissions simulated by the model were evaluated
against flux measurements (or model estimates that had previously been
evaluated with flux data) from a wide range of environments, and agreement
between modelled and simulated values was generally good. By using a dynamic
vegetation model, effects of canopy composition, disturbance history, or
trends in CO2 concentration can be assessed. We show here for five
model test sites that the suggested CO2-inhibition of leaf-isoprene
metabolism can be large enough to offset increases in emissions due to
CO2-stimulation of vegetation productivity and leaf area growth. When
effects of climate change are considered atop the effects of atmospheric
composition the interactions between the relevant processes will become even
more complex. The CO2-isoprene inhibition may have the potential to
significantly dampen the expected steep increase of ecosystem isoprene
emission in a future, warmer atmosphere with higher CO2 levels; this
effect raises important questions for projections of future atmospheric
chemistry, and its connection to the terrestrial vegetation and carbon
cycle. |
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