Source to Sink of Lignin Phenols in a Subtropical Forest of Southwest China

In biodiverse forest ecosystems, plant diversity has been reported to increase plant-derived lignin accumulation and soil organic carbon (SOC) storage. However, little is known about the fate of lignin and its degradation dynamics from plant to soil. This process is critical for the formation of SOC, especially in natural forest ecosystems with diverse plant species. This study presents the lignin biomarker characteristics of several common plant species and in mixed litter. The study was conducted in 45 plots along a plant species diversity gradient in a subtropical forest located in southwest China. Our results demonstrate that lignin content and its biochemical characteristics in plant leaves vary among species, while different plant species also alter the content of lignin and its monomeric compounds in the litter. Lignin compounds are gradually disintegrated from plant leaf to litter and then to soil, further indicating that plant-derived lignin from plant sources contributes to the formation and accumulation of forest SOC. These findings provide novel information on the linkage between tree species diversity and lignin accumulation while indicating the role of plant-derived lignin on SOC storage. These results may be useful in predicting forest soil C dynamics in Earth system models.