Glacier forefields are the newly exposed landscapes formed by retreating glaciers. As glaciers retreat, their forefields provide a unique opportunity to study the order and timing of biotic colonization, and how this influences the structure of successive ecological communities. In the last century glaciers across most of the cryosphere have receded at an unprecedented pace. Many studies have been published from different parts of the world testing hypotheses about how soil ecosystems are responding to rapid, contemporary deglaciation events. Using the information from these published studies, our objective was to use a meta-analysis approach to test whether there are any common, predictable patterns of community assembly in response to glacial recession. To collect relevant data from published studies we used the Web of Science indexing service and the Google Scholar database using different combinations of search terms. A total of 157 unique articles were found using these search terms. Of these, articles containing soil biotic richness and abundance data from glacial retreat areas that were suitable for informing our hypothesis were included in our analysis.
Results/Conclusions
The results indicated that Actinobacteria and Acidobacteria were consistently abundant along the chronosequence. However, the proportion of Proteobacteria and Bacteriodetes were dominant in soils that had been exposed for less than 90 years and gradually decreased in older soils. Analysis of fungal communities revealed that members of Basidiomycota followed by Ascomycota were predominant throughout the chronosequence. Among nematode trophic groups, bacterial feeders dominated soils from 0 to 80 years since deglaciation but start to decline after 50 years. In contrast, plant-feeding nematodes gradually increased and were dominant in soils that were exposed for more than 80 years since the glacial recession. Predatory nematodes were completely absent in soils that had been deglaciated for more than 5000 years. The results of our analysis reveal replicated patterns of phylogenetic and functional diversity associated with post-glacial-recession community assembly. From these patterns, we infer fundamental processes responsible for shaping them, including strong environmental filters, and biotic properties, such as dispersal kernels and biotic interactions. Thus, our work leverages an understanding of how past and present soil ecosystems are responding to deglaciation to inform predictions of how contemporary soil ecosystems will respond to future environmental changes.