The Contribution of Fe(III) Reduction to Soil Carbon Mineralization in Montane Meadows Depends on Soil Chemistry, Not Parent Material or Microbial Community.
In: Journal of Geophysical Research. Biogeosciences, Jg. 128 (2023-05-01), Heft 5, S. 1-14
Online
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Zugriff:
The long‐term stability of soil carbon (C) is strongly influenced by organo‐mineral interactions. Iron (Fe)‐oxides can both inhibit microbial decomposition by providing physicochemical protection for organic molecules and enhance rates of C mineralization by serving as a terminal electron acceptor, depending on redox conditions. Restoration of floodplain hydrology in montane meadows has been proposed as a method of sequestering C for climate change mitigation. However, dissimilatory microbial reduction of Fe(III) could lead to C losses under increased reducing conditions. In this study, we explored variations in Fe‐C interactions over a range of redox conditions and in soils derived from two distinct parent materials to elucidate biochemical and microbial controls on soil C cycling in Sierra Nevada montane meadows. Soils derived from basalt showed greater rates of Fe(III)‐reduction at increasing soil moisture levels than granitic soils. Increases in Fe(III) reduction, however, were only associated with elevated rates of C mineralization in one basalt soil. Known Fe(III)‐reducing taxa were present in all samples but neither the relative abundance nor richness of Fe(III)‐reducers corresponded with measured rates of Fe(III) reduction. Under reducing conditions, Fe(III)‐reduction was only coupled to C mineralization in the soil with the greatest amount of Fe‐oxide bound C. However, Fe‐oxide ‐bound C was below theoretical limits for C sorption onto Fe‐oxides and not detectable in all soils. Overall, our results suggest that "what's there" in terms of soil chemistry may be a more important driver of C mineralization coupled to Fe(III) reduction than "who's there" in the microbial community. Plain Language Summary: The ability of soils to sequester and store carbon may depend, in large part, on associations between soil minerals and carbon molecules. Iron is associated with some of the oldest and most persistent soil carbon. However, in saturated soils microbial utilization of iron can lead to the loss of soil carbon. In this study, we explored how microbial utilization of iron under different soil moisture levels impacts rates of soil carbon loss and whether geologic differences in parent material or microbial community composition explain patterns between sites. To test this, we incubated soils from basalt and granitic parent material at different levels of soil moisture and tested rates of iron utilization and carbon decomposition. Differences in parent material impacted microbial utilization of iron but increases in iron utilization were only coupled to soil carbon decomposition in one soil. Iron reducing bacteria were present in all soils, regardless of rates of iron utilization, and differences in microbial community composition did not impact rates of iron utilization or soil carbon decomposition. Overall, our results suggest that site‐specific soil chemistry may impact iron‐carbon interactions more than microbial community composition or parent material. Key Points: Differences in parent material were associated with differences in rates of Fe(III) reduction but not C mineralizationMixotrophic ability of many Fe(III)‐reducers may partially explain the lack of pattern observedSoil chemistry may exert stronger controls over dissimilatory Fe(III)‐reduction than microbial community composition [ABSTRACT FROM AUTHOR]
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The Contribution of Fe(III) Reduction to Soil Carbon Mineralization in Montane Meadows Depends on Soil Chemistry, Not Parent Material or Microbial Community.
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Autor/in / Beteiligte Person: | Reed, Cody C. ; Dunham‐Cheatham, Sarrah M. ; Castle, Sarah C. ; Vuono, David C. ; Sullivan, Benjamin W. |
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Zeitschrift: | Journal of Geophysical Research. Biogeosciences, Jg. 128 (2023-05-01), Heft 5, S. 1-14 |
Veröffentlichung: | 2023 |
Medientyp: | academicJournal |
ISSN: | 2169-8953 (print) |
DOI: | 10.1029/2022JG007325 |
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