The role of laccase in stabilization of soil organic matter by iron in various plant-dominated peatlands: degradation or sequestration?
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The association of organic matter with iron (Fe-OM associations) is recognized as an important stabilization mechanism for soil organic matter. Our objective was to assess the factors regulating stabilization of soil organic matter by iron in various plant-dominated peatlands, and the role of laccase in the formation of Fe-OM associations.
We investigated Fe-bound OC content and related physicochemical and biochemical parameters in four plots with different successional vegetation, and a set of simulations was conducted to investigate the association of Fe and peat-derived dissolved organic carbon catalysed by laccase.
Our results indicate Fe-bound OC content varies regularly with the succession gradients, and a significant positive relationship between laccase activities and Fe-bound OC content was found (R = 0.77, P < 0.05). Although laccase degradation of recalcitrant polyphenolics is related with the CO2 release from peat soils (R = 0.697; P < 0.05), the simulation results confirmed laccase can significantly promote the formation of Fe-OM association.
We propose that laccase plays a unique multifunctional role in the peatland carbon cycle. That is, while laccase degrades refractory organic matter such as lignin, it may enhance carbon sequestration by promoting the formation of Fe-OM association, which is particularly effective in acidic peat environments containing abundant iron and laccase-producing fungi.
KeywordsPeatland Carbon cycle Soil organic matter Fe-OM associations Laccase Stabilization
This work was supported by the National Natural Science Foundation of China (NSFC 41472316), the Hebei Provincial Department of Finance (2121299) and the Fundamental Research Funds for the Central University (CUG170104). We also thank the anonymous reviewers for their valuable suggestions.
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