Stronger linkage of diversity-carbon decomposition for rare rather than abundant bacteria in woodland soils

Soil microbial diversity is important for maintaining ecosystem functions. However, the linkage between microbial diversity, especially rare and abundant bacterial diversity, and carbon decomposition remains largely unknown. In this study, we assessed the establishment and maintenance of rare and abundant bacterial alpha-diversities at the taxonomic and phylogenetic levels and their linkages with soil carbon decomposition separately in four Chinese woodlands. Compared to abundant bacteria, rare bacteria showed higher community diversity, tighter phylogenetic clustering, wider environmental breadth, stronger phylogenetic signals, and higher functional redundancy. The assembly of the abundant bacterial subcommunity was governed by stochastic (59.2%) and deterministic (41.8%) processes, whereas the assembly of the rare bacterial subcommunity was mainly dominated by deterministic processes (85.8%). Furthermore, total phosphorus, soil pH, and ammonium nitrogen balanced stochastic and deterministic processes in both rare and abundant bacterial subcommunities. Our results reveal that rare bacteria displayed stronger environmental adaptability and environmental constraint. Importantly, the alpha-diversities of rare taxa, rather than abundant taxa, were significantly related to carbon decomposition. This study provides a holistic understanding of biogeographic patterns of abundant and rare bacteria and their alpha-diversities in relation to carbon decomposition, thus helping us better predict and regulate carbon dynamics under the background of global climate change.

Automated summary

Soil microbial diversity, especially rare and abundant bacterial diversity, plays a crucial role in maintaining ecosystem functions, but its linkage with carbon decomposition is poorly understood. This study investigated the establishment and maintenance of rare and abundant bacterial diversity and their relationship with soil carbon decomposition in four Chinese woodlands. The results showed that rare bacteria had higher community diversity, stronger phylogenetic signals, and higher functional redundancy compared to abundant bacteria. The assembly of the bacterial subcommunities was governed by both stochastic and deterministic processes, with the rare bacterial subcommunity mainly dominated by deterministic processes. Furthermore, the alpha-diversities of rare taxa, rather than abundant taxa, were significantly related to carbon decomposition.