Beech leaf litter lignin degradation and transformation as influenced by mineral phases

To investigate whether lignin transformations are influenced by mineral phases, an incubation experiment with mixtures of beech leaf litter and Fe oxide, Al hydroxide, or birnessite was conducted. Fe oxide reduced lignin decomposition to 39% of the lignin initially present as compared to 50% in the control, whereas in the Al hydroxide experiment only 11% of the lignin was degraded. Lignin side chain oxidation was enhanced in the presence of Fe oxide and birnessite. The most important properties of the mineral phases, with respect to their influence on lignin transformations, are their effect on microbial availability of organic matter and their ability to oxidize organic compounds.