Contrasting successional trajectory of microbial community convergence between two glacier forelands of the High Arctic

Abstract

Glacier forelands are ideal places to study patterns and processes of ecological succession but microbial succession is relatively poorly understood compared to plant succession. We investigated the successional changes in microbial communities along the chronosequences in forelands of two different glaciers (Austre Lovenbreen: AL and Blomstrandbreen: BS) in Svalbard. Both prokaryotic and eukaryotic microbial communities were analyzed using MiSeq sequencing of group-specific marker genes (e.g. 16S/18S rRNA gene, and ITS region). Ordination analysis revealed that all microbial communities shifted from early to later successional stage following deglaciation in both glacier forelands, suggesting that microbial community compositions were changed in a predictable way along chronosequences. Overall differences in bacterial communities were explained primarily by edaphic factors such as soil pH, whereas fungal communities differed more by vegetation type and coverage. Interestingly, there was a contrasting convergence pattern in microbial communities in both glacier forelands. Microbial communities were converged toward later successional stage in AL, while the opposite trend of community convergence was observed in BS. This result shows that successional age since glacier retreat is not always a single driver of community convergence at later stage of succession, but alternate factors such as geochemistry and geomorphology could also lead to distinct convergence pattern of microbial communities.