Distinct effects of volcanic cone types on soil microbiomes: Evidence from cinder cone and spatter cone

Volcanic cones, as essential components of the terrestrial ecosystem, provide an excellent model for studying the soil formation process, fertility and structure. However, there have not been any studies comparing soil microbial differences between cinder cones and spatter cones. To complement this lack of knowledge, we characterized the compositions of soil microbiomes between cinder cone and spatter cone sites using Illumina MiSeq high-throughput sequencing. Compared with spatter cone sites, cinder cone sites had higher microbial richness and greater abundance of arbuscular mycorrhizal (AM) fungi, which were found to work as keystone taxa. The co-occurrence network showed more complex interspecies relationships in spatter cone than in cinder cone; however, there was a larger proportion of positive correlations in cinder cone than in spatter cone. The functional composition profiles indicated that carbohydrate metabolism and amino acid metabolism were significantly enhanced in spatter cone and that there was a strong positive correlation between the two. Soil fungal communities were likely to be more resilient and resistant to Wulanhada volcanic activity than bacterial communities, which may have been due to the effects of the larger number of keystone taxa in soil fungal communities. Structural equation modeling (SEM) demonstrated that aboveground biomass and soil moisture exerted a significant impact on soil microbial communities and that alpha diversity was the biggest positive contributor of microbial multifunctionality. Our findings indicate the prospect of exploring the characteristics of the soil microbial communities in volcanoes of different types.