Rare prokaryotic sub-communities dominate the complexity of ecological networks and soil multinutrient cycling during long-term secondary succession in China's Loess Plateau

Unraveling the succession of microbial communities is a core ecological research topic. Yet few studies have focused on how long-term secondary succession affects the functional profiles and ecological processes of abundant and rare microbial subcommunities. Here, we used amplicon sequencing and GeoChip analysis to explore the ecological functions of abundant and rare biospheres and their correlation with soil multinutrient cycling. Samples for this study were collected from a well-established secondary succession chronosequence that spans >30 years of dryland ecosystem development on the Loess Plateau of China. Although both abundant and rare subcommunities shifted with succession, the changing of beta-diversity of the microbial communities was primarily driven by species replacement of the rare biosphere. Phylogenetic changes of abundant and rare taxa were associated with their functional traits, which dominated the diversity-related selection along all succession ages. Neutral theory analysis indicated that the assemblage of abundant taxa over all successional ages was regulated by dispersal homogenizing and ecological drift. The null model revealed that homogeneous and variable selection were the dominant assembly processes for rare subcommunities compared with abundant species. pH and nitrogen content were the paramount drivers determining the assembly of microbial communities and functional genes, consistent with the importance of environmental filtering. Furthermore, the rare biosphere had a paramount role in the entire ecological network and was the major driver for most soil processes such as C, N, and S cycling. Nonetheless, a significant portion of soil P cycling was regulated by abundant taxa. Collectively, our study provides insight into the mechanisms underlying microbial community assembly and soil microbedriven functional changes in biogeochemical processes during secondary succession. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

Microbial community succession in dryland ecosystems on the Loess Plateau of China was studied over a 30+ year period. Abundant and rare microbial subcommunities were found to shift during succession, with the rare biosphere driving changes in beta diversity. Phylogenetic changes were associated with functional traits, indicating diversity-related selection. The assembly of abundant taxa was regulated by dispersal homogenizing and ecological drift, while rare subcommunities were affected by homogeneous and variable selection processes. pH and nitrogen content were key drivers of microbial community assembly, with the rare biosphere playing a crucial role in soil processes such as C, N, and S cycling.