Terrestrial ecosystems play important roles in carbon (C) cycle. The loss of wetlands for croplands results in a release of significant amount of C from soil organic matter (SOM) into atmosphere. Wetland restoration from croplands has potential for C sequestration. However, restored wetlands emit methane (CH4), the second most important greenhouse gas. Emiquon floodplain restoration, the largest in Illinois of USA, was launched in 2007. The overall goal of this study was to study C dynamics in the restored wetland from croplands at Emiquon Preserve using an inventory approach and eddy-flux method. Soil samples were collected along 100-m long transects in 2009 and 2013. In addition, organic C (OC) storage of aboveground plants were sampled and estimated in 2009. In addition, we have estimated SOC storage in two Illinois natural marsh and sedge meadow. The soil organic C (SOC) storages in the two natural wetlands provide good references for C sequestration potential of SOM in restored wetlands. A CHN Elemental Analyzer (PerkinElmer 2440) was used to determine the C concentration of soil and plant samples. Using the eddy covariance technique, we have measured carbon dioxide (CO2) and CH4 flux of the restored wetlands since late 2014.
Results/Conclusions
The inventory measurements indicated that the SOC storage at Emiquon increased from 33.90 Mg /ha in 2009 to 48.03 Mg/ha in 2013. The aboveground biomass OC storage accounted for 3.69 Mg/ha in 2009. The preliminary analysis of the flux data showed this restored wetland is a C sink, although the CH4 flux has offset the C sink. The SOC storage of natural marsh and sedge meadow was 75.2 Mg/ha and 128.6 Mg/ha in 2011, respectively. This suggests that the restored wetland at Emiquon has potential to sequestrate more C in future. In conclusion, the restored wetland from croplands at Emiquon was a C sink and has potential for sequestrating more C over time as well as provides other important ecological services.