Multistate assessment of wetland restoration on CO2 and N2O emissions and soil bacterial communities

• Wetland restoration did not exacerbate CO2 or N2O emissions.
• Soil bacterial communities were correlated with edaphic factors rather than land use.
• Restored wetlands had lower soil C and N, and higher pH compared to natural wetlands.

Over the last 200 years, wetlands have been converted to other land uses leading to the loss of approximately 53% of wetlands in the continental United States. In the late 1980's, policies were instated to mitigate further wetland loss through wetland creation and restoration. Restored wetlands provide important ecosystem services, such as filtration of nutrients and wildlife habitat. However, these benefits could be offset by increased greenhouse gas production. We assessed the impact of wetland conversion to agriculture and restoration on CO2 and N2O emissions and microbial communities in three land use types: wetlands with native vegetation (natural); wetlands converted to agricultural management (converted); and restored wetlands (restored). Soil properties varied among land use types. Most notably, soils from restored and converted sites had the lowest C and N, and higher pH. Multivariate analysis of soil properties showed the pocosin wetlands in North Carolina separating from all other locations, regardless of land use. Soil bacterial communities showed a similar trend with communities from North Carolina soils separating from the others with no significant effect of land use or season. Furthermore, land use did not have a significant effect on CO2 or N2O emissions, although there was significant temporal variation in CO2 emissions. These findings indicate that while wetland conversion and restoration may alter some soil properties, these alterations do not appear to be great enough to override the underlying geographic and edaphic influences on soil bacterial communities. Furthermore, wetland restoration did not lead to increased N2O emission at the dates sampled.