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| Titel |
Speed of Carbon Cycling in Grassland Ecosystems by Destructive and Non-destructive Techniques |
| VerfasserIn |
O. Gavrichkova, I. Inglima, C. Lubritto, F. Cotrufo, D. Papale, R. Valentini |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250022116
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| Zusammenfassung |
| The allocation of recently assimilated C to below- vs. aboveground plant components and the
time this C remains inside the ecosystem are the key uncertainties in global terrestrial C
models. Recent studies reported the time lag between the photosynthetic C uptake and its
following respiration through the rooting systems in the magnitude from minutes to
days. Studies in situ are still not numerous, covering few plant functional types and
ecosystems. The methodology is not unique, destructive and non-destructive techniques
with different shortcomings are involved and it is not clear if obtained results are
comparable.
In situ pulse labeling of plants in 13CO2atmosphere was performed in a Mediterranean
grassland site (Amplero, Italy), aiming to advance the understanding of allocation patterns
and speed of cycling of recently assimilated C in such types of ecosystem. Raw isotopic
values of respired 13CO2, mean residence time and mean age of this C in aboveground and
belowground compartments were estimated. Time lag between photosynthesis and
root-derived respiration was obtained also by destructive mesh exclusion technique,
performing bimonthly measurements of soil respiration and its components and relating this
data to the changes in gross primary production (GPP) from eddy covariance station installed
in the study site.
Two distinct pools of C were recognized: a fast turning over pool, which integrates the
assimilates of the current day and fuels mainly aboveground respiration, and slower turning
over pool which integrates C with higher mean residence time and fuels mainly belowground
respiration. The peak in aboveground respiration happened between 2 and 4 hours after the
pulse labeling. Root-derived respiration of recently assimilated 13CO2 peaked between 16-24
hours after the label introduction. The last value goes in accord with the time lag of 20 hours
obtained by destructive mesh exclusion method. The fact that such type of partitioning
technique is widely used in environmental studies, and is often coupled with eddy covariance
measurements makes it promising for the estimation of the speed of C cycling within
and between ecosystems, however up to now it was rarely used for this purposes. |
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