16S and ITS amplicon sequencing analysis on samples collected in 2023 from the InsubrePolar site near Toolik Field Station in Alaska
SEASONAL AND SPATIAL DYNAMICS OF ARCTIC TUNDRA MICROBIOMES: ABIOTIC DRIVERS AND IMPLICATIONS FOR METHANE CYCLING
Arctic tundra plays a central role in the global carbon cycle. Specifically, different types of Arctic tundra can act either as a source or as a sink of CH₄. Microbial communities colonizing the Arctic active layer and permafrost in different tundra ecosystems are supposed to contribute to CH₄ fluxes through their metabolic activities. Herein, we investigated the structure of prokaryotic (bacterial and archaeal) and fungal communities across three tundra sites (dry heath, moist acidic tussock, and wet sedge) in Arctic Alaska. We studied the spatial and seasonal variations of local microbial communities by sampling multiple soil horizons at the beginning (July) and at the end (September) of the Arctic growing season. Our results indicated that prokaryotic and fungal communities exhibited a significant diversity among sites and soil horizons. In addition, prokaryotic communities’ structure varied during the Arctic growing season both in the active layer and in the permafrost layer, although this variation was site-specific. In contrast, fungal community structure remained stable across the growing season. The main drivers of the observed microbial diversity were abiotic factors such as soil grain size, soil organic matter (SOM), and water content. These factors were proven to influence the taxonomic distribution of aerobic methanotrophs and anaerobic methanogens, which in turn depended on the whole microbial communities aerobically and anaerobically degrading SOM. Overall, our findings indicated that site-specific soil properties and microbial communities’ structure impact on CH₄ fluxes in Arctic tundra, underscoring the need to jointly consider microbial-mediated processes and key regulators of permafrost carbon feedback when predicting Arctic greenhouse gas fluxes in response to climate change.