Soil available nitrogen and phosphorus affected by functional bacterial community composition and diversity as ecological restoration progressed

Available nitrogen (N) and phosphorus (P) are the most common elements limiting the success of ecosystem restoration. Soil microbial communities, harbouring the alkaline metalloprotease (apr) gene and alkaline phosphatase activity gene (phoD), play a crucial role in regulating and maintaining soil available N and P. However, the dynamics ofapr- andphoD-harbouring bacteria and their contributions to regulating soil available N and P balances remain largely unexplored as ecological restoration proceeded. In this study, we investigated the community dynamics ofapr- andphoD-harbouring bacteria during the plant growing season in association with the long-term passive (40 years) and active (35 years) restoration of degraded ecosystems. The results showed that soil available N steadily increased while available P typically decreased as ecosystem restoration proceeded. The passive and active restoration efforts resulted in a higher available N balance than available P balance. Passive and active restoration significantly enhanced the abundances, diversities of OTUs, and beta diversities ofapr- andphoD-harbouring bacteria. Notably, the alpha diversity ofapr-harbouring bacteria did not keep pace with that ofphoD-harbouring bacteria with increased site age. Our results indicated that the distinct beta diversities of theapr- andphoD-harbouring bacteria were the predominant cause of the variation in the available N and P balance. Our findings provide a foundation for a better understanding of the distinct responses ofapr- andphoD-harbouring bacteria to ecological restoration and how they ultimately regulate the available N and P balance in the developing soils of degraded ecosystems.