the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Carbon isotope discrimination during litter decomposition can be explained by selective use of substrate with differing δ13C
Abstract. Temporal dynamics of C isotopic composition (δ13C) of CO2 and leaf litter was monitored during a litter decomposition experiment using Arbutus unedo L., as a slow decomposing model substrate. This allowed us (1) to quantify isotopic discrimination variation during litter decomposition, and (2) to test whether selective substrate use or kinetic fractionation could explain the observed isotopic discrimination. Total cumulative CO2-C loss (CL) comprised 27% of initial litter C. Temporal evolution of CL was simulated following a three-C-pool model. Isotopic composition of respired CO2 (δRL) was higher with respect to that of the bulk litter. The isotopic discrimination Δ(L/R) varied from −2‰ to 0‰ and it is mostly attributed to the variations of δRL. A three-pool model, with the three pools differing in their δ13C, described well the dynamic of Δ(L/R), in the intermediate stage of the process. This suggests that the observed isotopic discrimination between respired CO2 and bulk litter is in good agreement with the hypothesis of successive consumption of C compounds differing in δ13C during decomposition. However, to explain also 13C-CO2 dynamics at the beginning and end of the incubation the model had to be modified, with discrimination factors ranging from −1‰ to −4.6‰ attributed to the labile and the recalcitrance pool, respectively. We propose that this discrimination is also the result of further selective use of specific substrates within the two pools, likely being both the labile and recalcitrant pool of composite nature. In fact, the 2‰ 13C enrichment of the α-cellulose observed by the end of the experiment, and potentially attributable to kinetic fractionation, could not explain the measured Δ(L/R) dynamics.
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RC C22: 'Review of Carbon isotope discrimination ...by J. Ngao and M. F. Cotrufo', Anonymous Referee #1, 24 Jan 2011
- AC C181: 'Responses to anonymous referee #1', Jerome Ngao, 08 Mar 2011
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RC C55: 'Reveiw comment', Anonymous Referee #2, 04 Feb 2011
- AC C185: 'Responses to anonymous referee #2', Jerome Ngao, 08 Mar 2011
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RC C22: 'Review of Carbon isotope discrimination ...by J. Ngao and M. F. Cotrufo', Anonymous Referee #1, 24 Jan 2011
- AC C181: 'Responses to anonymous referee #1', Jerome Ngao, 08 Mar 2011
-
RC C55: 'Reveiw comment', Anonymous Referee #2, 04 Feb 2011
- AC C185: 'Responses to anonymous referee #2', Jerome Ngao, 08 Mar 2011
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Cited
10 citations as recorded by crossref.
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- Effects of environmental variation on stable isotope abundances during typical seasonal floodplain dry season litter decomposition G. Zhang et al. 10.1016/j.scitotenv.2018.02.298
- Environmental Effects on Carbon Isotope Discrimination from Assimilation to Respiration in a Coniferous and Broad-Leaved Mixed Forest of Northeast China H. Diao et al. 10.3390/f11111156
- Turnover and isotopic fractionation of carbon from maize leaves as influenced by clay type and content in constructed soil media W. Yang et al. 10.1007/s00374-015-1085-1
- Early-stage changes in natural 13C and 15N abundance and nutrient dynamics during different litter decomposition M. Gautam et al. 10.1007/s10265-016-0798-z
- Stable isotope variation during fungal colonisation of leaf detritus in aquatic environments M. Costantini et al. 10.1016/j.funeco.2014.05.008
- Aggregate size and glucose level affect priming sources: A three-source-partitioning study J. Tian et al. 10.1016/j.soilbio.2016.03.013