Comparison of Microbial Community Structures and Functions During the Wet and Dry Seasons

The dataset presents a comprehensive analysis of the microbial community structure and its functional potential in relation to nitrogen transformation processes across the hyporheic zone. The figure integrates taxonomic abundance distributions with a functional heatmap to elucidate how microbial patterns vary with soil depth (0-100 cm) and between the wet (June) and dry-wet transition (September) seasons. The relative abundance histograms at both the Phylum and Genus levels reveal distinct vertical stratification and seasonal shifts in the dominant microbial taxa. At the phylum level, the top 10 phyla (e.g., Proteobacteria, Chloroflexi, Actinobacteria, Nitrospirae, Firmicutes, Actinobacteria, Gemmatimonadetes, Candidate_division_WS3, Planctomycetes, and Bacteroidota) showed significant variations in their proportional abundance along the depth gradient and between seasons, indicating that subsurface hydrology and seasonal water table fluctuations strongly shape the community composition. Similarly, the histogram of the top 15 genera highlights more specific taxonomic responses, with certain genera becoming predominant at specific depths or during a particular season. This spatial and temporal patterning suggests that the hyporheic interface is a dynamic ecotone where microbial communities are finely tuned to changing redox conditions, organic matter availability, and water flux driven by surface water-groundwater interactions. The dataset provides a critical functional perspective by linking specific genera to key nitrogen transformation processes, including nitrification, denitrification, DNRA, nitrogen fixation, and combined nitrification-denitrification. Genera involved in aerobic processes like nitrification were often more abundant or active in shallower layers (e.g., 0-40 cm), where oxygen infiltration from surface water is likely higher. In contrast, taxa implicated in anaerobic processes such as denitrification and DNRA frequently showed increased relative abundance or association in deeper layers (60-100 cm), where anoxic conditions prevail due to longer groundwater residence times. The heatmap illustrates clear seasonal variations in the abundance of genera linked to different N-cycling pathways.