Different ecological patterns of abundant and rare microbial communities across wetlands formation and succession after land-use change.

Abundant and rare microorganisms play distinct yet critical ecological and evolutionary roles, and understanding their characteristics and responses to environmental change is essential for improving ecological prediction and informing ecosystem management. Here, we investigated the community patterns of abundant and rare bacterial and fungal taxa along a land-use gradient from farmland to naturally successional wetlands and an artificially managed wetland in coal-mining subsidence areas. Results showed that during wetland formation and succession, rare subcommunities exhibited higher community stability, whereas abundant subcommunities displayed broader niche breadth. A significant positive correlation between α-diversity and community stability was observed only in rare subcommunities. Specifically, community stability was positively correlated with rare bacterial α-diversity but negatively correlated with rare fungal α-diversity. Species replacement contributed more strongly to β-diversity in rare subcommunities, while richness differences played a greater role in shaping β-diversity of abundant subcommunities. Co-occurrence network analysis revealed that abundant subcommunities occupied more central positions in microbial networks, characterized by higher centralization and connectance. Dissolved organic carbon and pH were identified as the most important environmental factors driving the variations in abundant and rare subcommunities, respectively. In addition, the potential microbial multifunctionality of rare subcommunities increased during wetland succession, whereas that of abundant subcommunities decreased; artificial management significantly reduced the potential microbial multifunctionality of both abundant and rare subcommunities. Notably, only in abundant subcommunities, α-diversity showed positive association with potential microbial multifunctionality. Overall, our findings demonstrate the complementary ecological roles of abundant and rare microbial subcommunities in regulating community responsiveness, stability, and potential microbial multifunctionality. These results highlight the importance of considering abundant and rare microbial subcommunities separately when developing management strategies during the succession of newly formed wetlands.