DOI: 10.1111/gcb.12908
论文题名: Lignin decomposition is sustained under fluctuating redox conditions in humid tropical forest soils
作者: Hall S.J. ; Silver W.L. ; Timokhin V.I. ; Hammel K.E.
刊名: Global Change Biology
ISSN: 13541013
出版年: 2015
卷: 21, 期: 7 起始页码: 2818
结束页码: 2828
语种: 英语
英文关键词: Humid tropical forest
; Iron oxidation
; Iron reduction
; Lignin
; Oxygen
; Redox
; Soil moisture
; Soil organic matter
; Terrestrial carbon cycle
Scopus关键词: carbon cycle
; decomposition
; forest soil
; humid tropics
; iron
; lignin
; oxidation
; oxygen
; redox conditions
; reduction
; soil moisture
; soil organic matter
; tropical forest
英文摘要: Lignin mineralization represents a critical flux in the terrestrial carbon (C) cycle, yet little is known about mechanisms and environmental factors controlling lignin breakdown in mineral soils. Hypoxia is thought to suppress lignin decomposition, yet potential effects of oxygen (O2 ) variability in surface soils have not been explored. Here, we tested the impact of redox fluctuations on lignin breakdown in humid tropical forest soils during ten-week laboratory incubations. We used synthetic lignins labeled with 13C in either of two positions (aromatic methoxyl or propyl side chain Cβ ) to provide highly sensitive and specific measures of lignin mineralization seldom employed in soils. Four-day redox fluctuations increased the percent contribution of methoxyl C to soil respiration relative to static aerobic conditions, and cumulative methoxyl-C mineralization was statistically equivalent under static aerobic and fluctuating redox conditions despite lower soil respiration in the latter treatment. Contributions of the less labile lignin Cβ to soil respiration were equivalent in the static aerobic and fluctuating redox treatments during periods of O2 exposure, and tended to decline during periods of O2 limitation, resulting in lower cumulative Cβ mineralization in the fluctuating treatment relative to the static aerobic treatment. However, cumulative mineralization of both the Cβ - and methoxyl-labeled lignins nearly doubled in the fluctuating treatment relative to the static aerobic treatment when total lignin mineralization was normalized to total O2 exposure. Oxygen fluctuations are thought to be suboptimal for canonical lignin-degrading microorganisms. However, O2 fluctuations drove substantial Fe reduction and oxidation, and reactive oxygen species generated during abiotic Fe oxidation might explain the elevated contribution of lignin to C mineralization. Iron redox cycling provides a potential mechanism for lignin depletion in soil organic matter. Couplings between soil moisture, redox fluctuations, and lignin breakdown provide a potential link between climate variability and the biochemical composition of soil organic matter. Copyright © 2015 John Wiley & Sons Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/61672
Appears in Collections: 影响、适应和脆弱性
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作者单位: Department of Environmental Science, Policy and Management, University of California, BerkeleyCA, United States; Department of Biochemistry, Wisconsin Energy Institute, University of Wisconsin, MadisonWI, United States; US Forest Products Laboratory, Madison, WI, United States; Department of Bacteriology, University of Wisconsin, MadisonWI, United States
Recommended Citation:
Hall S.J.,Silver W.L.,Timokhin V.I.,et al. Lignin decomposition is sustained under fluctuating redox conditions in humid tropical forest soils[J]. Global Change Biology,2015-01-01,21(7)