Soil properties and not plant factors affect both abundant and rare microbial taxa after thinning in a mixed stand of Cunninghamia lanceolata and Sassafras tzumu

Thinning is an effective management step for sustainable forest development,yet less attention is paid to the restoration of soil microbiota after thinning.In this study,both abundant and rare soil microbial communities(i.e.,bacterial,fungal),were evaluated under various thinning treatments in a mixed stand of Cunninghamia lanceolata and Sassafras tzumu using Mi Seq sequencing.Thinning did not significantly change either abundant or rare bacterial and fungal community composition,but affected their alpha diversity.The Shannon–Wiener indexes of rare fungal taxa under medium thinning were significantly lower than in the light thinning(P<0.05 level).Xanthobacteraceae dominated the abundant bacterial taxa,and Saitozyma and Mortierlla the abundant fungal taxa.The most common rare bacterial taxa varied;there was no prevalent rare fungal taxa under different thinnings.In addition,soil available nitrogen,total phosphorus,and p H had significant effects on rare bacterial taxa.Nutrients,especially available phosphorus,but not nitrogen,affected abundant and rare soil fungi.The results indicate that soil properties rather than plant factors affect abundant and rare microbial communities in soils of mixed stands.Thinning,through mediating soil properties,influences both abundant and rare bacterial and fungal communities in the mixed C.lanceolata and S.tzumu stand.

Stochastic community assembly of abundant taxa maintains the relationship of soil biodiversity-multifunctionality under mercury stress

Soil abundant taxa diversity positively related to multifunctionality under Hg stress.•Microbial network complexity of soil abundant taxa supported the strength of SBF.•Stochastic assembly of soil abundant subcommunity supported the strength of SBF.•Stochastic ratio was the most important predictor for the strength of SBF.It is known that soil microbial communities are intricately linked to multiple ecosystem functions and can maintain the relationship between soil biodiversity and multifunctionality(SBF)under environmental stresses.However,the relative contributions and driving forces of abundant and rare taxa within the communities in maintaining soil biodiversity-multifunctionality relationship under pollution stresses are still unclear.Here,we conducted microcosm experiments to estimate the importance of soil abundant and rare taxa in predicting these relationships under heavy metal mercury(Hg)stress in paired paddy and upland fields.The results revealed that the diversity of abundant taxa,rather than rare taxa,was positively related to multifunctionality,with the abundant subcommunity tending to maintain a larger proportion of soil functions including chitin degradation,protein degradation,and phosphorus mineralization.Soil multitrophic network complexity consisting of abundant species showed positive correlations with biodiversity and multifunctionality,and supported the strength of SBF within a network complexity range.Stochastic assembly processes of the abundant subcommunity were positively correlated with the strength of SBF,although stochastic processes decreased the biodiversity and the multifunctionality,respectively.After simultaneously accounting for multiple factors on the strength of SBF,we found that the stochastic community assembly ratio of abundant taxa was the most important predictor for SBF strength under Hg stress.Our results highlight the importance of abundant taxa in supporting soil multifunctionality,and elucidate the linkages between community assembly,network complexity and SBF relationship under environmental stresses.

Response and assembly of abundant and rare taxa in Zaopei under different combination patterns of Daqu and pit mud:from microbial ecology to Baijiu brewing microecosystem

The quality and aroma of strong-flavor Baijiu are mainly dependent on Daqu,pit mud(PM),and the interaction of both.However,little is known about how their combination patterns affect the microbiome and metabolome of Zaopei,especially the metabolic function of rare taxa.Here,an experiment on industrial size was designed to assess the effects of 6 combinations(3 kinds of Daqu×2 kinds of PM)on the composition and assembly of different taxa,as well as the flavor profile.The results showed that Zaopei's microbiota was composed of a few abundant taxa and enormous rare taxa,and rare bacterial and abundant fungal subcommunities were significantly affected by combination patterns.The assembly processes of abundant/rare taxa and bacterial/fungal communities were distinct,and environmental changes mediated the balance between stochastic and deterministic processes in rare bacteria assembly.Furthermore,specific combination patterns improved the flavor quality of Zaopei by enhancing the interspecies interaction,which was closely related to rare taxa,especially rare bacteria.These findings highlighted that rare bacteria might be the keystone in involving community interaction and maintaining metabolic function,which provided a scientific foundation for better understanding and regulating the brewing microbiota from the viewpoint of microbial ecology.