Positive correlation between soil bacterial metabolic and plant species diversity and bacterial and fungal diversity in a vegetation succession on Karst

The hypothesis that positive links exist among plant taxonomic diversity, belowground microbial taxonomic and metabolic diversities was tested for four secondary vegetation successional stages (tussock (T), shrub (S), secondary forest (SF) and primary forest (PF)) in Huanjiang county, SW China. Soil bacterial communities were characterized by DNA fingerprinting and metabolic profiling. Along the succession, Shannon diversity indices followed the order SF>PF>S>T for plant taxonomic diversity, T>SF>PF>S for bacterial operational taxonomic diversity, SF>T>S>PF for fungal operational taxonomic diversity, and SF>PF>S>T for bacterial metabolic diversity. Significant positive correlations were found between bacterial and fungal taxonomic diversities. However, there was no significant correlation between soil microbial taxonomic diversity and bacterial metabolic diversity. Two-way ANOVA revealed that vegetation and season, as well as their interaction, had significant effects on soil microbial (fungal and bacterial) taxonomic diversities, but that there were no seasonal effects on metabolic diversity. However, PCA and MANOVA revealed highly significant differences among the bacterial community-level physiological profiles, reflecting the successional sequence. The findings from this survey support the notion that there are strong interactions between aboveground and belowground communities and suggest that bacterial metabolic and plant taxonomic diversities, but not microbial taxonomic and metabolic diversities, can be correlated.