Soil pH Determining the Assembly Processes of Abundant and Rare Bacterial Communities in Response to Cultivation Modes in Lemon Farmlands

Here, the biogeographic patterns of abundant and rare bacterial taxa in lemon farmlands with different cultivation modes were examined using the dataset obtained from high-throughput sequencing. The abundant sub-communities exhibited a lower richness, a similar abundance proportion, and lower compositional variations than rare taxa. With regard to different cultivation modes, a lower richness but higher beta-diversity distance was observed in abundant bacterial taxa from greenhouse soils compared to other open field farmlands. In addition, some potential indicators, including Proteobacteria, Chloroflexi, and Bacteroidota, were found to be enriched in the abundant sub-communities in greenhouse soils. Moreover, a stronger environmental-related distance-decay of similarity was observed in abundant taxa from greenhouse soils, but in hilly-converted farmlands for rare taxa. The abundant sub-communities were more sensitive to environmental changes and more tightly phylogenetically clustered. In contrast, homogeneous selection dominated the assembly of rare taxa, which was insensitive to dispersal limitations. Soil pH was identified as the key factor to driving the assembly of soil bacterial communities, with a more deterministic and stochastic assembly for abundant and rare taxa, respectively, at the neutral environments.