Trade-offs in soil carbon protection mechanisms under aerobic and anaerobic conditions
© 2020 John Wiley & Sons Ltd.
| Veröffentlicht in: | Global change biology. - 1999. - 26(2020), 6 vom: 01. Juni, Seite 3726-3737 |
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| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2020
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| Zugriff auf das übergeordnete Werk: | Global change biology |
| Schlagworte: | Journal Article 13C NMR C3/C4 plant DOC anaerobic anoxic carbon stable isotope iron reduction litter decomposition mineral-associated carbon mehr... |
| Zusammenfassung: | © 2020 John Wiley & Sons Ltd. Oxygen (O2 ) limitation is generally understood to suppress oil carbon (C) decomposition and is a key mechanism impacting terrestrial C stocks under global change. Yet, O2 limitation may differentially impact kinetic or thermodynamic versus physicochemical C protection mechanisms, challenging our understanding of how soil C may respond to climate-mediated changes in O2 dynamics. Although O2 limitation may suppress decomposition of new litter C inputs, release of physicochemically protected C due to iron (Fe) reduction could potentially sustain soil C losses. To test this trade-off, we incubated two disparate upland soils that experience periodic O2 limitation-a tropical rainforest Oxisol and a temperate cropland Mollisol-with added litter under either aerobic (control) or anaerobic conditions for 1 year. Anoxia suppressed total C loss by 27% in the Oxisol and by 41% in the Mollisol relative to the control, mainly due to the decrease in litter-C decomposition. However, anoxia sustained or even increased decomposition of native soil-C (11.0% vs. 12.4% in the control for the Oxisol and 12.5% vs. 5.3% in the control for the Mollisol, in terms of initial soil C mass), and it stimulated losses of metal- or mineral-associated C. Solid-state 13 C nuclear magnetic resonance spectroscopy demonstrated that anaerobic conditions decreased protein-derived C but increased lignin- and carbohydrate-C relative to the control. Our results indicate a trade-off between physicochemical and kinetic/thermodynamic C protection mechanisms under anaerobic conditions, whereby decreased decomposition of litter C was compensated by more extensive loss of mineral-associated soil C in both soils. This challenges the common assumption that anoxia inherently protects soil C and illustrates the vulnerability of mineral-associated C under anaerobic events characteristic of a warmer and wetter future climate |
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| Beschreibung: | Date Completed 15.09.2020 Date Revised 15.09.2020 published: Print-Electronic Citation Status MEDLINE |
| ISSN: | 1365-2486 |
| DOI: | 10.1111/gcb.15100 |