A comparison of the spatial variability of denitrification and related soil properties in restored and natural depression wetlands in Indiana, USA

Abstract

We characterized and compared the variability and spatial patterns of denitrification and soil properties in two natural and two restored depressional wetlands in northern Indiana, USA. Soil properties included soil moisture content, bulk density, plant-available N (NO3-N, NH4-N), soil organic carbon (C), total nitrogen (N), and C:N ratio. Restored wetlands had greater denitrification and higher spatial variability than natural wetlands. Further, restored wetlands had greater bulk density and C:N ratios. In contrast, natural wetlands had greater soil moisture, plant-available N, organic C, and total N. Similar to denitrification, soil moisture, bulk density, NO3-N, total N, and C:N ratios had greater variance in restored wetlands than in natural wetlands. Denitrification and several soil properties exhibited positive global spatial autocorrelation, though trends differed between the individual wetlands for soil properties. Variogram analysis suggested little spatial structure in variables at the chosen observational scale. Denitrification hot spots were detected in natural and restored wetlands, though these hot spots did not correspond to hot spots of any of the other soil variables. Overall, spatial patterns of denitrification and soil properties differed between natural and restored wetlands and should be considered when assessing effectiveness of restored wetlands at providing ecosystem services, such as N removal and C storage.