The relative importance of litter nutrients, C-related, and physical traits in controlling litter decomposition vary substantially between deciduous and evergreen species

Abstract

Litter decomposition plays important roles in maintaining ecosystem function and controlling carbon (C) and nutrient cycle in terrestrial ecosystems. Thus, understanding its fundamental controlling factors is of great value to improve the accuracy of biologically driven global carbon (C) cycle of prediction models. In this study, we conducted a field decomposition experiment with 205 tree species litters and quantified the relative importance of litter nutrients, C-related and physical traits in controlling litter decomposition in different plant functional groups. The results showed that across all species, litter nutrients (65.1%) explained more variation in litter decomposition than physical (17.5%) and C-related traits (17.4%). Litter nutrients had lower explanation for deciduous species (47.0%) than for evergreen species (77.9%), while C-related and physical traits had higher explanation for deciduous litters (20.5% and 32.5%) than for evergreen species (13.5% and 8.6%), suggesting that the importance of these three categorized litter traits in controlling litter decomposability was plant functional type dependent. Nitrogen, tannins and water saturation capacity were the best predictors of litter decomposition among nutrients, C-related and physical traits, respectively, irrespective of plant functional types. In sum, our findings highlight the differences in the roles of initial litter nutrients, C-related and physical traits in regulating litter decomposition and suggest that litter trait-decomposition relationships vary substantially between deciduous and evergreen species, necessitating their explicit consideration in Earth’s C cycle models to improve the accuracy of predicting litter decomposition.