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| Titel |
Environmental and plant control on ecosystem respiration in a beech forest in Central Italy |
| VerfasserIn |
Gabriele Guidolotti, Giorgio Matteucci, Ana Rey, Paolo De Angelis |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250051498
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| Zusammenfassung |
| The net amount of carbon that is absorbed by or emitted from a forest ecosystem (NEE) is the
result of the difference between gross primary production (GPP) and total ecosystem
respiration (TER). Most of the variability on NEE among different ecosystems has been
attributed to the variability of the TER rates. With the objective of analysing the response of
TER to environmental “drivers”, we compared the seasonal dynamics of NEE with the major
components of TER: soil (RS), stem (RW) and leaf (RL) CO2 effluxes. The NEE was
measured by the eddy-covariance technique, whereas the TER components by dynamic
chambers.
Over the one year study period the temporal variability of TER was mostly explained by
changes in RS(63%), according to the variation in soil temperature and soil water content. Rw
rates of the dominant trees were systematically higher than rates of the co-dominant ones,
except for the measurements carried out after leaf fall: autumn and winter. The temporal
variation of Rw was strongly related to air temperature, showing an exponential
increase of CO2 emission with increasing temperature. The temperature sensitivity
(Q10) of Rw was not significantly different between the two categories of trees
(dominant and co-dominant), while the basal respiration rate was higher in the dominant
trees.
Under common temperature RL expressed on a leaf area basis differed significantly
between the upper and the lower part of the canopy. Among all the leaf parameters analysed,
total non-structural carbohydrates (TNC) were found to be a good predictor of leaf
respiration, explaining 76% of the daily variability of RL.
A comparison of different approaches to scale-up the measured component of TER was
also done. Our results show the relative importance of the environmental factors on TER
variability, demonstrating a relative increase in plant respiration when water was limiting soil
processes. |
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