Leaf litter decomposition is the main process of soil nutrient dynamics. Observational and experimental evidences increasingly suggest that arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) tree species have dramatically different litter decomposition rates. However, understanding of the roles of microbes in leaf litter decomposition remains limited, especially in tropical and subtropical forest. Here, we compared the effects of soil microbes in litter decomposition rates between four AM and four ECM trees in a subtropical forest.
In the field, a hyphae isolation experiment was carried on to characterize soil microbes on leaf litter decomposition beneath AM and ECM trees. In the greenhouse, bactericide and fungicide were used to test how bacterias and fungi influence litter decomposition. For both experiments, the original leaf litter chemical properties were measured and final decomposition rates were calculated. Soil microbes isolates were sequenced and the activity of extracellular enzymes was determined after harvesting the litterbags.
Results/Conclusions
We found that leaf litters decayed more rapidly in AM soils than that in ECM soils, and there were significant difference in bacteria and fungi community compositions, and extracellular enzymes between AM and ECM soils. Particularly, the extracellular enzymes activities and saprotrophic fungi abundance were significantly higher in AM soils than that in ECM soils. Furthermore, fungi played a more important role than bacterias in both AM and ECM soils.
Our findings demonstrate that AM trees have higher leaf litter decomposition rates than ECM trees, and saprotrophic fungi determine the leaf litter decomposition. This provides evidence that saprotrophic fungi could be an important contributor to nutrient absorption strategies and nutrient dynamics in the forest.