Evolution of the Soil Bacterial Community Structure during the Development of Pinus massoniana Plantations in Subtropical China

Soil bacterial communities can form links between forest trees and soils, but the effect of stand age on the soil bacterial communities and diversity is still unclear. The technique of IlluminaMiSeq high-throughput sequencing was used to detect abundance and diversity of the 16S rRNA gene of bacteria to evaluate the evolution of the soil bacterial communities and diversity changes over time (13, 25, 38 and 58 years old) of Pinus massoniana Lamb. plantations in subtropical China. The results showed that the succession of P. massoniana plantations significantly influenced the structure and diversity of the bacterial communities. The Shannon and Simpson diversity indexes of soil bacteria were the highest in 25 year-old P. massoniana plantations, whereas the diversity index reached the lowest value in the 38-year-old P. massoniana plantations. The Chao1 and Ace indexes were the highest in 58 year old P. massoniana plantations. At the phylum level, 35 phyla were obtained in all treatments, among which Acidobacteria (32.82%), Proteobacteria (29.75%), Actinobacteria (11.07%) and Chloroflexi (10.52%) were the predominant phyla. The dominant genera were Acidothermus, Candidatus_Solibacter, Variibacter, Bradyrhizobium and Acidibacter (relative abundance larger than 2%). Hierarchical clustering and principal component analysis (PCA) revealed that stand age significantly affected the soil microbial community structure and as a result, the soil microbial community structures in the 13- and 25 year old plantations differed sharply from those in the 38- and 58 year old plantations. The soil bacterial communities, both in terms of structure and diversity, were significantly correlated with soil pH, total nitrogen, and ammonium nitrogen (P < 0.01). In conclusion, stand age greatly altered the diversity and structure of the bacterial communities, and soil pH and ammonium nitrogen were the potential environmental factors associated with the bacterial community variations. (C) 2019 Friends Science Publishers