Cryptogams signify key transition of bacteria and fungi in Arctic sand dune succession

Abstract

O_LIPrimary succession models focus on aboveground vascular plants. However, the prevalence of mosses and lichens, i.e. cryptogams, suggests they play a role in soil successions. Here, we explore whether effects of cryptogams on belowground microbes can facilitate progressive shifts in sand dune succession. C_LIO_LIWe linked aboveground vegetation, belowground bacterial and fungal community, and soil chemistry in six successional stages in Arctic inland sand dunes: bare sand, grass, moss, lichen, ericoid heath and mountain birch forest. C_LIO_LICompared to the bare sand and grass stages, microbial biomass and the proportion of fungi increased in the moss stage, and later stage microbial groups appeared despite the absence of their host plants. The microbial communities of the lichen stage resembled the communities in the vascular plant stages. Bacterial community correlated better with soil chemistry than with vegetation, whereas the correlation of fungi with vegetation increased with vascular vegetation. C_LIO_LIDistinct bacterial and fungal patterns of biomass, richness, and plant-microbe interaction showed that the aboveground vegetation change structured the bacterial and fungal community differently. The nonalignment of aboveground vs. belowground changes suggests that cryptogams can drive succession towards vascular plant dominance through microbially mediated facilitation in eroded Arctic soil. C_LI