Asymmetric effects between tree and understorey litters on mixed litter decomposition in temperate Quercus variabilis forest

Litter decomposition is a critical process of biogeochemical cycles of ecosystem. While growing evidences have shown the decomposition rates of litter mixture are different from those of single-species litters, the mutual effects between different functional type species in the mixture remain inconclusive. A field litterbag experiment was conducted to determine the mutual effects of three functional type plants [tree (Quercus variabilis), shrub (Lindera glauca), and herb (Lygodium japonicum)] during the decomposition in a temperate oak forest. After 400 days of in situ incubation, the mass loss rate of each species-specific in the mixture was greater than that decomposed as monoculture, showing the greatest mass loss in the three-species litter mixture. In addition, the decomposition constant for each species was stimulated while mixed with other species. The presence of L. glauca leaf litter significantly elevated total N (15.0%) and C loss (8.92%) of Q. variabilis leaf litter, and the existence of Q. variabilis leaf litter also led to enhanced total N (10.4%) and C (9.1%) release of L. glauca leaf litter. The addition of L. japonicum in the mixed litters showed substantially positive effects on total N (16.5% and 10.8%) and C (10.6% and 14.2%) release of both L. glauca and Q. variabilis litters. In contrast, neither Q. variabilis nor L. glauca litter exhibited effects on the total N and C loss of L. japonicum litter. Our results indicate that the mutual effects between different functional types on nutrient release were asymmetric in the mixed litters. The role of species specific in the mixture should be highlighted while evaluated the nonadditive effects in the leaf litter mixing experiments. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

The mutual effects between different functional type plants in mixed litters during decomposition were found to have asymmetric impacts on nutrient release. The presence of one species in the mixture influenced the nutrient release of other species, highlighting the importance of species-specific effects in leaf litter mixing experiments.