Leaf and Root Litter Species Identity Influences Bacterial Community Composition in Short-Term Litter Decomposition

Abstract Background: Microorganisms play a crucial role in litter decomposition in terrestrial ecosystems. However, it remains unclear, which effects of leaf litter and root species on bacterial community composition and diversity after one year's decomposition. Methods: The leaf and fine roots litters of Robinia pseudoacacia , Quercus acutissima , Pinus tabulaeformis and Pinus densiflora , which are the dominant afforestation species in Mount Tai, were analysed using the Nylon litterbag method and Illumina Miseq high-throughput sequencing for the amplification of bacterial 16S rRNA V4-V5. We measured the remaining litter mass and the bacterial community composition and assessed the effects of leaf and root litter species on the bacterial community after one-year decomposition periods.Results: (1) The remaining masses of leaf and fine roots litters of the four plant species were significantly influenced by organ type and species. The remaining mass of fine root litter was smaller than that of leaf litter for broad-leaved species, and the opposite result was found for coniferous species. (2) The observed species Chao1 and phylogenetic diversity values were significantly lower for leaf litters than for fine root litter. The community richness index was positively correlated with the C content, C:N and lignin content and negatively correlated with N:P, N content and P content. The bacterial community structure differed significantly among leaf and root litter decomposition for the four species ( p <0.05). The bacterial community structure in leaf litter was most highly correlated with the initial N content and N:P. The bacterial community structure in fine roots was most highly correlated with the lignin content. (3) The bacterial phyla Bacteroidetes , Acidobacteria and Gemmatimonadetes were significantly affected by litter and species type, and the relative abundances of Firmicutes and Chloroflexi were only affected by litter type. The relative abundances of Acidobacteria , Firmicutes and Chloroflexi in fine root litter were higher than those in leaf litter, while the opposite result was found for Bacteroidetes . The bacterial genera Burkholderia-Paraburkholderia , Sphingomonas and Mucilaginibacter were affected by litter type ( p <0.05). The relative abundance of Burkholderia-Paraburkholderia in fine root litter was higher than that in leaf litter, while the opposite result was found for Bradyrhizobium , Sphingomonas and Mucilaginibacter . Pearson correlation analysis showed that the average relative abundance of the dominant phyla and genera was affected by the initial litter properties, especially for Bacteroides , Acidobacteria , Burkholderia , and Sphingomonas . Conclusions: Litter type, interaction between litter type and species were important than species in shaping the bacterial diversity and community composition in decomposing litter. And this were affected by initial chemical properties of the litter.