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| Titel |
Does soil moisture overrule temperature dependence of soil respiration in Mediterranean riparian forests? |
| VerfasserIn |
C. T. Chang, S. Sabate, D. Sperlich, S. Poblador, F. Sabater, C. Gracia |
| 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 ; 11, no. 21 ; Nr. 11, no. 21 (2014-11-13), S.6173-6185 |
| Datensatznummer |
250117674
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| Publikation (Nr.) |
 copernicus.org/bg-11-6173-2014.pdf |
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| Zusammenfassung |
| Soil respiration (SR) is a major component of ecosystems' carbon cycles and
represents the second largest CO2 flux in the
terrestrial biosphere. Soil temperature is considered to be the
primary abiotic control on SR, whereas soil moisture is the secondary control
factor. However, soil moisture can become the dominant control on SR
in very wet or dry conditions. Determining the trigger that
makes soil moisture as the primary control factor of SR will
provide a deeper understanding on how SR changes under the projected
future increase in droughts. Specific objectives of this study were
(1) to investigate the seasonal variations and the relationship
between SR and both soil temperature and moisture in a Mediterranean
riparian forest along a groundwater level gradient; (2) to determine
soil moisture thresholds at which SR is controlled by soil
moisture rather than by temperature; (3) to compare SR responses under
different tree species present in a Mediterranean riparian forest
(Alnus glutinosa, Populus nigra and Fraxinus
excelsior). Results showed that the heterotrophic soil
respiration rate, groundwater level and 30 cm integral soil
moisture (SM30) decreased significantly from the riverside moving uphill and showed a pronounced seasonality. SR rates showed
significant differences between tree species, with higher SR for
P. nigra and lower SR for A. glutinosa. The lower
threshold of soil moisture was 20 and 17% for
heterotrophic and total SR, respectively. Daily mean SR rate was
positively correlated with soil temperature when soil moisture
exceeded the threshold, with Q10 values ranging from 1.19 to
2.14; nevertheless, SR became decoupled from soil temperature when
soil moisture dropped below these thresholds. |
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