Abstract: Carbon (C) quality of non-leaf litter is closely related to decomposition rate and plays a vital role in terrestrial ecosystem C sequestration. However, to date, the global patterns and influencing factors of non-leaf litter C quality remain unclear. Here, using meta-analysis method, we quantified the characteristics and driving factors of the initial C quality of non-leaf litter (bark, branch, flower, fruit, root, stem, and wood) with 996 observations collected from 279 independent publications, including the concentrations of total C, lignin, cellulose, and hemicellulose. Results showed that (1) only total C and cellulose concentrations significantly varied among different types of non-leaf litter; (2) C quality is higher (i.e., lower concentration) in bark, branch, root, stem and wood litter from angiosperms than gymnosperms, from herbaceous than woody plants, from broadleaved than coniferous trees, and from arbuscular mycorrhizal (AM) than ectomycorrhizal (ECM) plants (except for hemicellulose concentration); and (3) the impacts of different geographic features on C quality of non-leaf litter differed among different litter types, while soil properties generally exhibited strong impacts. Overall, our results clearly show the global patterns of C quality and associated influencing factors for different types of non-leaf litter, which would be helpful for a better understanding of role of non-leaf litter in terrestrial ecosystem C cycling and for the improvement of C cycling models.

Key words: total carbon, lignocellulose, plant functional type, geographical feature, climate, soil properties, decomposition