Data from: Carbon versus nitrogen release from root and leaf litter are modulated by litter position and plant functional type

Litters of leaves and roots of different qualities occur naturally above- and belowground, respectively, where they decompose in contrasting abiotic and biotic environments. Therefore, ecosystem carbon (C) and nitrogen (N) dynamics can be strongly affected by the combination of litter position and quality. However, it is poorly understood how C versus N turnover of litters depends on the interplay among plant functional type (PFT), organs, traits, and litter position. In a semi-arid inland dune, soil surface and buried leaf litters and buried fine roots of 25 species across three PFTs (herbs, legume shrubs, and non-legume shrubs) were incubated for 3, 6, 9, 12, 18, and 24 months to investigate litter decomposition and C and N dynamics. Morphological and chemical (nutrient and NMR carbon) traits of initial litters of leaves and fine roots were determined. The litter decomposition rates (k values) of surface leaves and buried fine roots did not differ, but buried fine roots and buried leaf litter decomposed faster than surface leaf litter. Ratios of k values of surface leaves to buried leaves decreased with the leaf C:N ratio. Herbs and legume shrubs decomposed faster than non-legume shrubs for buried fine roots, but not for leaves. At given C loss, buried fine roots had higher N loss than leaf litters; legume shrubs with relatively higher N or lower C:N ratio had higher N loss than non-legume shrubs. Stronger positive relationships between C and N losses were shown in leaves and legume shrubs than in fine roots and non-legume shrubs, respectively. Synthesis: The generality of faster N release of legume litters at a given C release highlights the importance of legumes in N cycling in semi-arid ecosystems where N is the limiting factor. The dynamics and coordination of C versus N release as a function of litter quality are modulated by litter position and PFT. These findings have important implications for the development of process-based models on C and N cycles in the context of ongoing global change potentially altering the functional composition of plant communities and the relative quantities and qualities of aboveground versus belowground litter.Funding provided by: Strategic Priority Research Program of the Chinese Academy of Sciences*Crossref Funder Registry ID: Award Number: XDA23080302Funding provided by: National Key Research and Development Program of ChinaCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100012166Award Number: 2018YFE018280