Secondary successional forests undergo tightly-coupled changes in soil microbial community structure and soil organic matter

Soil microbes link aboveground and belowground ecosystem processes by modulating nutrient retention, recycling, and availability to plants. The diversity and abundance of soil microbes are influenced by biotic and edaphic factors such as plant communities and soil chemistry. Despite this general understanding, relatively few details are known about how soil microbial community structure responds to changing plant communities and soil chemistry associated with secondary forest succession. To address these gaps, we used 16S rRNA gene sequencing to investigate how diversity, composition and abundance of soil prokaryotic communities differed among five successional stages at two soil depths in a temperate forest, and then related these differences with soil properties. Oligotrophic prokaryotic taxa were more common in earlier successional stages, and community diversity declined at later forest successional stages. Prokaryotic diversity was consistently higher in topsoil than subsoil. Prokaryotic community composition varied with respect to soil organic matter (SOM) properties. The relative abundances of specific carbon (C) functional groups (e.g., aliphatic C groups, aromatic C groups and polysaccharides) revealed by mid-IR spectroscopy were strongly related with prokaryotic community composition. Overall, this study revealed that changes in soil prokaryotic community structure (diversity, composition and taxa abundance) paralleled changes in plant communities and soil chemistry associated with forest succession, and that these changes can be inferred through changes in SOM properties.