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

Abstract

Microorganisms play a crucial role in litter decomposition in terrestrial ecosystems. The leaf and fine root litters of Robinia pseudoacacia Linn., Quercus acutissima Carr., Pinus tabulaeformis Carr. and Pinus densiflora Sieb. were analysed using the nylon litter bag method and Illumina MiSeq high-throughput sequencing for the amplification of bacterial 16S rRNA V4–V5. We assessed the effects of leaf and root litter species on the bacterial community after one year’s decomposition. The results showed that (1) the remaining mass of fine root litter was smaller than that of the leaf litter for R. pseudoacacia and Q. acutissima, while the opposite result was found for P. tabulaeformis and P. densiflora. (2) The bacterial community structure in leaf litter was most highly correlated with the initial N content and N:P, while that 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, whereas the relative abundances of Firmicutes and Chloroflexi were only affected by litter tissues. 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 tissues (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’s correlation analysis showed that the relative abundances of the dominant phyla and genera were affected by the initial litter properties, especially for Bacteroides, Acidobacteria, Burkholderia and Sphingomonas. These findings indicate that litter tissues and their interactions with species are more important than the species in shaping the bacterial diversity and community composition, which was affected by the initial chemical properties of the litter.