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| Titel |
Trends in ecosystem water use efficiency are potentially amplified by
plasticity in plant functional traits |
| VerfasserIn |
Theodoros Mastrotheodoros, Christoforos Pappas, Peter Molnar, Paolo Burlando, Trevor F. Keenan, Pierre Gentine, Simone Fatichi |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250149121
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| Publikation (Nr.) |
 EGU/EGU2017-13443.pdf |
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| Zusammenfassung |
| Increasing atmospheric carbon dioxide concentrations stimulate photosynthesis and reduce
stomatal conductance, modifying plant water use efficiency. We analyzed eddy covariance
flux tower observations from 20 forested ecosystems across the Northern Hemisphere. For
these sites, a previous study showed an increase in inherent water use efficiency (IWUE) five
times greater than expectations. We used an updated dataset and robust uncertainty
quantification to analyze these contemporary trends in IWUE. We found that IWUE increased
in the last 15-20 years by roughly 1.4% yr−1, which is less than previously reported, but still
2.8 times greater than theoretical expectations. Numerical simulations by means of an
ecosystem model based on temporally static plant functional traits (i.e. model parameters) do
not reproduce this increase. We tested the hypothesis that the observed increase in
IWUE could be attributed to changes in plant functional traits, potentially triggered
by environmental changes. Simulation results accounting for trait plasticity (i.e.
by changing model parameters such as specific leaf area and maximum Rubisco
capacity) match the observed trends in IWUE, with an increase in both leaf internal
CO2 concentration and gross ecosystem production (GEP), and with a negligible
trend in evapotranspiration (ET). This supports the hypothesis that changes in plant
functional traits of about 1.0% yr−1 can explain the observed IWUE trends and
are consistent with observed trends of GEP and ET at larger scales. Our results
highlight that at decadal or longer time scales trait plasticity can considerably influence
the water, carbon and energy fluxes with implications for both the monitoring of
temporal changes in plant traits and their representation in Earth system models. |
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