Aerobic environments in combination with substrate additions to soil significantly reshape depth-dependent microbial distribution patterns in Zoige peatlands, China

Climate warming is leading to the water table drawdown in peatlands, and a shift in the structure and productivity of vegetation communities. These events may alter the availability of oxygen and substrate utilized by soil microbes, which may impact the microbial decomposition rate in the different peat layers. We investigated the bacterial and fungal communities in surface (0–25 cm), subsurface (25–75 cm) and deep (> 76 cm) layers, and assessed the response of these communities to aerobic conditions and substrate of varying complexity additions to soils in Zoige peatlands, China. Bacterial and fungal communities varied in different peat layers, with the largest community sizes in the surface layer. The aerobic incubation significantly altered bacterial and fungal community compositions in the subsurface and deep layers. Both bacterial and fungal community size increased by 155% and 53% in the deep layer, respectively. Under aerobic conditions, substrate additions to soils significantly shifted fungal community compositions across all soil layers but not bacteria. Soil substrate increased the fungal community size by 130%–1000% in the subsurface layer without substantially altering bacterial abundance in any of the layers. Our results highlight the importance of vertical stratification in bacterial and fungal communities and the depth-dependent changes that occur under the influence of an aerobic environment and changes in the quality of the substrate. We suggest that fungi may be more sensitive to climate change than bacteria, especially in subsurface layers. Thus, this is an essential factor that needs to be considered when analyzing the role of microbes in peatland carbon dynamics.