Periglacial substrates vacated by retreating glaciers represent extreme environments characterized by intense radiation, severe nutrient limitations and rapid diurnal temperature oscillations that challenge organismal establishment and survival. As such, periglacial habitats serve as models with simple communities that enable study of mechanisms that drive early community assembly. Here, we synthesize results of a series of studies at the Lyman Glacier forefront in the North Cascade Mountains of Washington State with a goal of contrasting bacteria, fungi and plants as they interact over time. Visual surveys and data acquisition enabled characterization of plant communities, whereas microbial community analyses combined a variety of high throughput sequencing and phylogenetic community analyses.
Although microbial inocula are drawn from regional pools and accumulate over time, the combined data provided little support for their increasing richness over time since deglaciation, in contrast to dynamics often reported for plant communities. We conclude that organismal guilds follow distinct trajectories, so universal generalizations are likely to prove difficult. Clear conclusions are further complicated by landscape heterogeneity that leads to patchiness and community mosaics, each potentially facing distinct controls that dictate community dynamics. While an understanding of organismal dynamics and trajectories is fundamental to elucidate patterns of community assembly, knowledge of soil microbial activities and the ecosystem services they provide in early successional environments is mandatory for deeper appreciation of the dynamics of these communities.