*WINNER* The relation of microbial biomass carbon with denitrification and nutrient retention in restored floodplain wetlands

Abstract

Restoration activities have been implemented in the lower Mississippi River basin through the Wetlands Reserve Program (WRP) to enhance essential functions by restoring wetlands. Soil can be a zone of significant nutrient retention in wetlands by providing an environment for microbial development and nutrient processing. The objective of this study was to assess soil microbe-based ecosystem function in three restored riparian wetlands in Western Kentucky, focusing on the relationship between microbial biomass and nutrient removal. We hypothesized that nutrient retention, and specifically denitrification is directly related to microbial biomass carbon (MBC). At each easement, thirty sediment cores were collected and used to measure a suite of soil processes and properties, including soil nitrogen (N) and phosphorus (P) uptake rates, denitrification potential, soil moisture, and MBC. MBC was significantly higher in undisturbed older habitat, followed by remnant forest, and lowest in the shallow water areas. Denitrification potential, and N and P uptake were strongly correlated with MBC and soil moisture. Our results suggest that increasing total soil microorganism biomass is an indicator for monitoring improvements in ecological functions in restored wetlands, with potentially important long-term consequences for denitrification and nutrient retention.