Patterns and determinants of plant‐derived lignin phenols in coastal wetlands: Implications for organic C accumulation

Abstract

1. As a major plant-derived soil organic carbon (SOC) component, lignin phenols are unique biomarkers that reflect biogeochemical characteristics under different vegetation compositions and climatic zones in coastal wetlands. However, the latitudinal patterns of plant-derived lignin phenols to SOC and their link with the stability and controlling mechanisms remain poorly understood.2. A total of 156 soil samples from 39 sites along a 5000 km coastal transect, were taken to explore the effects of biological and environmental controls on the patterns of lignin phenols. Lignin phenols had contents ranging from 1.91 to 83.3 mg g −1 OC, and a positive correlation was detected in grass-dominated salt marsh, but a weakly negative correlation in mangrove. Positive correlations between SOC or lignin content and C/V or S/V (the cinnamyl-or syringyl-tovanillyl) ratios were found, while overall negative correlations between SOC or lignin content and (Ad/Al) V or (Ad/Al) S (the acid-to-aldehyde of vanillyl or syringyl units) ratios were detected, respectively, which confirmed the validity of these lignin biomarker degradation parameters.3. Our findings revealed that plant C inputs and monomer ratios directly influenced the capacity of lignin phenols in soils. Lignin content and stabilization was mainly controlled by soil properties (i.e. pH, EC sand/clay). Mean annual temperature (MAT) influenced the patterns of lignin phenols both directly by increasing decomposition and indirectly by changing the vegetation and soil biogeochemistry (i.e. microbial substrate availability).

Microbial Necromass, Lignin, and Glycoproteins for Determining and Optimizing Blue Carbon Formation

“…Soil lignin phenols were determined through the process of copper oxide (CuO) oxidation and analyzed using an Agilent 7890B gas chromatography, coupled with a 7010B TQ mass spectrometer (Agilent). 22 The total lignin phenol content was calculated by summing the V monomers (vanillin, acetovanillone, and vanillic acid), S monomers (syringaldehyde, acetosyringone, and syringic acid), and C monomers (p-coumaric acid and ferulic acid). The ratios of acid/aldehyde for V phenol ((Ad/ Al) v) and S phenol ((Ad/Al) s) and the ratios of C/V and S/ V phenols to indicate the degree of microbial alteration and oxidation of lignin.…”

“…21 The lignin phenols have been quantified to contribute to 0.19−8.3% of the SOC pools in coastal wetlands. 22 Glycoprotein glomalin, which is generated by AM fungi, is assessed in the soil as glomalinrelated soil protein (GRSP). 23−25 These recalcitrant, hydrophobic, and sticky glycoproteins can enhance the accumulation of organic C in coastal wetlands through facilitating aggregate formation and stabilization.…”

“…It has been established that the contributions of microbial necromass C to the SOC pool range from 24 to 60% in terrestrial ecosystems, , while a few studies verified relatively fewer contributions in coastal wetlands. , Lignin, the second most abundant plant-derived organic compound after cellulose, plays a crucial role in controlling the rate of litter decomposition and contributes to the environmental loadings of carbon . The lignin phenols have been quantified to contribute to 0.19–8.3% of the SOC pools in coastal wetlands . Glycoprotein glomalin, which is generated by AM fungi, is assessed in the soil as glomalin-related soil protein (GRSP). − These recalcitrant, hydrophobic, and sticky glycoproteins can enhance the accumulation of organic C in coastal wetlands through facilitating aggregate formation and stabilization. − While a direct relationship or link may not be apparent among microbial necromass C, lignin phenol, and GRSP, it is still valuable to investigate their relative contributions to SOC accumulation, stability, and interaction in coastal wetlands.…”

Contributions of plant‐ and microbial‐derived residuals to mangrove soil carbon stocks: Implications for blue carbon sequestration

“…As a significant component of plant‐based SOC, lignin phenols serve as unique biomarkers reflecting the biogeochemical properties of various types of vegetation and climatic zones in coastal wetlands (Xia et al., 2023). Recently, researchers have proposed that lignin persists as unused residual energy in stable soil organic matter (SOM), due to the considerable energy expenditure needed for its breakdown (Gunina & Kuzyakov, 2022).…”

“…The combined VSC content is calculated to determine the total lignin content, which is subsequently used to estimate the input of terrigenous plant organic matter into the soil (Yang et al., 2022). The ratios of cinnamyl and vanillyl, and syringyl and vanillyl, signify the degree of lignin phenol decomposition, with lower values indicating more accessible lignin degradation (Xia et al., 2023).…”