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Summary: The mechanisms underlying microbial community dynamics and co‐occurrence patterns along ecological succession are crucial for understanding ecosystem recovery but remain largely unexplored. Here, we investigated community dynamics and taxa co‐occurrence patterns in bacterial and fungal communities across a well‐established chronosequence of post‐mining lands spanning 54 years of recovery. Bacterial community structures became increasingly phylogenetically clustered with soil age at early successional stages and varied less at later successional stages. The dynamics of bacterial community phylogenetic structures were determined by the changes in the soil vegetation cover along succession. The dynamics of fungal community phylogenetic structures did not significantly correlate with soil age, soil properties or vegetation cover, and were mainly attributed to stochastic processes. Along succession, the common decrease in the bacterial co‐occurrence complexity and in the average pairwise phylogenetic distances between co‐occurring bacteria implied a decrease in potential bacterial cooperation. The increased complexity of fungal co‐occurrence along succession was independent of phylogenetic relatedness between co‐occurring fungi. This study provides new sights into ecological mechanisms underlying bacterial and fungal community succession. [ABSTRACT FROM AUTHOR]

Microbial interconnections in soil are pivotal to ecosystem services and restoration. However, little is known about how soil microbial interconnections respond to slash-and-burn agriculture and to the subsequent ecosystem restoration after the practice. Here, we used amplicon sequencing and co-occurrence network analyses to explore the interconnections within soil bacterial and fungal communities in response to slash-and-burn practice and a spontaneous restoration (spanning ca. 60 years) of tropical forests after the practice, in Papua New Guinea. We found significantly higher complexity and greater variations in fungal networks than in those of bacteria, despite no significant changes observed in bacterial or fungal networks across successional stages. Within most successional stages, bacterial core co-occurrences (co-occurrences consistently present across all sub-networks in a stage) were more frequent than those of fungi, indicating higher stability of interconnections between bacteria along succession. The stable interconnections occurred frequently between bacterial taxa (i.e. Sporosarcina , Acidimicrobiale and Bacillaceae) and between ectomycorrhizal fungi (Boletaceae and Russula ochroleuca), implying important ecological roles of these taxa in the ecosystem restoration. Collectively, our results provide new insight into microbial interconnections in response to slash-and-burn agriculture and the subsequent ecosystem restoration, thus promoting a better understanding of microbial roles in ecosystem services and restoration. [ABSTRACT FROM AUTHOR]

Here, we investigated the patterns of microbial nitrogen cycling communities along a chronosequence of soil development in a salt marsh. The focus was on the abundance and structure of genes involved in N fixation ( nifH), bacterial and archaeal ammonium oxidation ( amoA; AOB and AOA), and the abundances of genes involved in denitrification ( nirS, nirK, nosZ). Potential nitrification and denitrification activities were also measured, and increases in nitrification were found in soils towards the end of succession, whereas denitrification became maximal in soils at the intermediate stages. The nifH, nirK and nirS gene markers revealed increases in the sizes of the respective functional groups towards the intermediate stage (35 years), remaining either constant (for nifH) or slightly declining towards the latest stage of succession (for nirK and nirS). Moreover, whereas the AOB abundance peaked in soils at the intermediate stage, that of AOA increased linearly along the chronosequence. The abundance of nosZ was roughly constant, with no significant regression. The drivers of changes in abundance and structure were identified using path analysis; whereas the ammonia oxidizers (AOA and AOB) showed patterns that followed mainly N availability, those of the nitrogen fixers followed plant diversity and soil structure. The patterns of denitrifiers were group-dependent, following the patterns of plant diversity ( nirK and nirS) and belowground shifts ( nosZ). The variation observed for the microbial groups associated with the same function highlights their differential contribution at different stages of soil development, revealing an interplay of changes in terms of niche complementarity and adaptation to the local environment. [ABSTRACT FROM AUTHOR]