The “no net loss” federal wetland policy holds that total wetland acreage and/or wetland quality should not decrease as a result of economic development, but should be maintained or increased through wetland mitigation and restoration activities. Carbon cycling and sequestration are important ecosystem functions in estuarine wetlands, but there has been very limited research on carbon dynamics in estuarine wetlands in the Pacific Northwest. We compared soil carbon dynamics in restored, disturbed (by diking or draining), and reference wetlands in both freshwater and saline conditions (6 sites total) in Coos Bay, Oregon. We measured seasonal in situ fluxes of methane and carbon dioxide, soil and carbon sequestration rates and pools, and microbial decomposition dynamics. Microbial decomposition dynamics were measured in the upper 30 cm of the soil by the production of methane and carbon dioxide, microbial catabolic profiles, and extracellular enzyme activity under anaerobic and aerobic conditions. We employed geochronology techniques to estimate soil and carbon sequestration rates and pools in reference sites.
Results/Conclusions
Our preliminary results indicate that restored wetlands generally perform more similarly, in microbial function, to reference sites than disturbed sites. Microbial catabolic profiles indicate similar utilization of carbon substrates between restored and reference sites, with disturbed sites performing significantly different. However, enzyme activity in restored sites displayed only a partial return of microbial function to reference levels. These results suggest that goal of maintaining or improving ecological functions in restored wetlands may be attained over time, but at present do not meet “no net loss” requirements.