In the Beginning ... It was Already the End Janeiro, Claudia; Santos, Rita; Teixeira, João ...
GE Portuguese journal of gastroenterology,
01/2020, Letnik:
27, Številka:
1
Report
The flux (R
s
) and carbon isotopic composition (δ
13
C
Rs
) of soil respired CO
2
was measured every 2 h over the course of three diel cycles in a Mediterranean oak woodland, together with ...measurements of the δ
13
C composition of leaf, root and soil organic matter (δ
13
C
SOM
) and metabolites. Simulations of R
s
and δ
13
C
Rs
were also made using a numerical model parameterised with the SOM data and assuming short-term production rates were driven mainly by temperature. Average values of δ
13
C
Rs
over the study period were within the range of root metabolite and average δ
13
C
SOM
values, but enriched in
13
C relative to the bulk δ
13
C of leaf, litter, and roots and the upper soil organic layers. There was good agreement between model output and observed CO
2
fluxes and the underlying features of δ
13
C
Rs
. Observed diel variations of 0.5 ‰ in δ
13
C
Rs
were predicted by the model in response to temperature-related shifts in production rates along a ∼3 ‰ gradient observed in the profile of δ
13
C
SOM
. However, observed δ
13
C
Rs
varied by over 2 ‰, indicating that both dynamics in soil respiratory metabolism and physical processes can influence short-term variability of δ
13
C
Rs
.
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