JS6-4:

The development of soil microbial community during vegetation recovery and pedogenesis on the new volcanic deposits of Miyake-jima

The plant-microbe-soil interaction plays an important role in the reconstruction of terrestrial ecosystem after geological disasters such as volcanic eruption. It is little known, however, how the soil microbial community develops in response to vegetation recovery on the new volcanic deposits. To explore this issue, we continually investigated the microbial community of the volcanic deposits derived from the eruption of Miyake-jima in 2000, on which the vegetation gradually recovered from the damage. According the investigation from 2009 to 2014, we found that: 1) In the volcanic deposits, the relative abundance of Oxalobacteraceae in Betaproteobacteria and Xanthomonadaceae in Gammaproteobacteria gradually increased with the vegetation recovery from barren land to grassland, while the proportion of Rhizobiales in Alphaproteobacteria increased in further development of woodland; 2) In the rhizosphere of pioneer plant Miscanthas condensatus, the proportion of Bradyrhizobium, Rhizobium, Granulicella, and Arthrobacter significantly increased from the initial colonizing stage to the later dominating stage, but that of Bulkholderia significantly decreased; 3) In the primary soil horizons on the volcanic deposits, the bacterial and archaeal 16S rRNA gene densities in the new soil layers (A and B layers) and litter layer (O layer) were significantly higher than those in the volcanic deposit layer (C layer). These findings suggest that the microbial community dramatically changes during the vegetation recovery on the newly exposed volcanic deposits. This process is characterized as follows: 1) several microbial groups correlate positively or negatively with plant species, 2) beneficial bacteria and pathogenic bacteria in the rhizosphere positively and negatively correlate with the pioneer plant colonization, respectively, and 3) microbial biomass positively correlate with the pedogenesis on the volcanic deposits.

keywords:ecosystem recovery,soil microbial community,pedogenesis,volcanic deposits,vegetation,pioneer plant