Temporal shifts in the explanatory power and relative importance of litter traits in regulating litter decomposition

Background: Litter traits critically affect litter decomposition from local to global scales. However, our under-standing of the temporal dynamics of litter trait-decomposition linkages, especially their dependence on plant functional type remains limited.Methods: We decomposed the leaf litter of 203 tree species that belong to two different functional types (decid-uous and evergreen) for 2 years in a subtropical forest in China. The Weibull residence model was used to describe the different stages of litter decomposition by calculating the time to 10%, 25% and 50% mass loss (Weibull t1/10, t1/4, and t1/2 respectively) and litter mean residence time (Weibull MRT). The resulting model parameters were used to explore the control of litter traits (e.g., N, P, condensed tannins and tensile strength) over leaf litter decomposition across different decomposition stages.Results: The litter traits we measured had lower explanatory power for the early stages (Weibull t1/10 and t1/4) than for the later stages (Weibull t1/2and MRT) of decomposition. The relative importance of different types of litter traits in influencing decomposition changed dramatically during decomposition, with physical traits exerting predominant control for the stages of Weibull t1/10 and MRT and nutrient-related traits for the stages of Weibull t1/4, and t1/2. Moreover, we found that litter decomposition of the early three stages (Weibull t1/10, t1/4, and t1/2) of the two functional types was controlled by different types of litter traits; that is, the litter decom-position rates of deciduous species were predominately controlled by nutrient-related traits, while the litter decomposition rates of evergreen species were mainly controlled by carbon-related traits. Conclusions: This study suggests that litter trait-decomposition linkages vary with decomposition stages and are strongly mediated by plant functional type, highlighting the necessity to consider their temporal dynamics and plant functional types for improving predictions of litter decomposition.

Automated summary

This study reveals the variation of litter traits and their dependence on plant functional type during litter decomposition. The results show that litter traits play different roles in different stages of decomposition, with physical traits being more important in the early stages and nutrient-related traits being more important in the later stages. Furthermore, litter decomposition rates of deciduous and evergreen species are controlled by different types of litter traits.