Abiotic correlates of microbial community structure and nitrogen cycling functions vary within wetlands

AbstractWe investigated patterns in denitrifier and NH3-oxidizer community structure and function along environmental gradients in midwestern USA wetlands. Denitrifier and NH3-oxidizer functional groups have contrasting sensitivities to O2 levels and other soil factors. Thus, variable environmental tolerance among and within functional groups can result in a range of microbial responses to the same environmental gradient. We compared microbial structure–function relationships in 2 restored wetlands in Illinois and 2 natural wetlands in Michigan. At each site, we established 4 transects perpendicular to the shore and placed 4 plots along each transect. We analyzed denitrifier and NH3-oxidizer community structure (assessed by molecular analysis of functional genes nosZ and amoA) and potential denitrification and nitrification activities (function) across the soil hydrologic gradient. Soil moisture and physicochemical measurements, including organic-matter content, pH, inorganic N levels, and texture, varied...