Long-term litter decomposition controlled by manganese redox cycling
- Soils Division, Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97330,, Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550,
- Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720,
- Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR 97331,
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529,
- Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550,
- Soils Division, Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97330,, Institut für Bodenlandschaftsforschung, Leibnitz-Zentrum für Agrarlandschaftsforschung (ZALF), 15374 Muuncheberg, Germany
Litter decomposition is a keystone ecosystem process impacting nutrient cycling and productivity, soil properties, and the terrestrial carbon (C) balance, but the factors regulating decomposition rate are still poorly understood. Traditional models assume that the rate is controlled by litter quality, relying on parameters such as lignin content as predictors. However, a strong correlation has been observed between the manganese (Mn) content of litter and decomposition rates across a variety of forest ecosystems. Here, we show that long-term litter decomposition in forest ecosystems is tightly coupled to Mn redox cycling. Over 7 years of litter decomposition, microbial transformation of litter was paralleled by variations in Mn oxidation state and concentration. A detailed chemical imaging analysis of the litter revealed that fungi recruit and redistribute unreactive Mn2+ provided by fresh plant litter to produce oxidative Mn3+ species at sites of active decay, with Mn eventually accumulating as insoluble Mn3+/4+ oxides. Formation of reactive Mn3+ species coincided with the generation of aromatic oxidation products, providing direct proof of the previously posited role of Mn3+-based oxidizers in the breakdown of litter. Our results suggest that the litter-decomposing machinery at our coniferous forest site depends on the ability of plants and microbes to supply, accumulate, and regenerate short-lived Mn3+ species in the litter layer. As a result, this observation indicates that biogeochemical constraints on bioavailability, mobility, and reactivity of Mn in the plant–soil system may have a profound impact on litter decomposition rates.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- 10-ERD-021; AC52-07NA27344; AC02-05CH11231
- OSTI ID:
- 1235146
- Alternate ID(s):
- OSTI ID: 1251089; OSTI ID: 1513787
- Report Number(s):
- LLNL-JRNL-671965
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Vol. 112 Journal Issue: 38; ISSN 0027-8424
- Publisher:
- Proceedings of the National Academy of SciencesCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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