Fate of Soil Organic Carbon During Wetland Loss

We carried out a 1.5-year study of the fate of organic carbon during experimental wetland loss using an herbicide at freshwater, brackish and saltwater emergent wetlands. Total carbon stocks in the upper 50 cm of the soil horizon were 15.0 +/- 0.5 kg C/m(2) (222.8 mt CO2e/ac) at the freshwater site, 11.1 +/- 0.9 kg C/m(2) (164.7 mt CO2e/ac) at the brackish site, and 8.5 +/- 1.4 kg C/m(2) (125.7 mt CO2e/ac) at the saltwater site. There were no significant differences detected in decomposition between the treatment and reference plots, which had 39.4 to 41.5 % material remaining by the end of the study at the three sites. The plots treated with herbicide had decreased elevation of -4.24 cm, -1.56 cm and -1.48 cm at the freshwater, brackish and saltwater sites, respectively, which equate to a mass loss of soil organic carbon of 1273 g C/m(2), 389 g C/m(2) and 207 g C/m(2), respectively. Results indicate statistically greater greenhouse gasses were emitted at the brackish and saltwater plots treated with herbicide compared to the reference plots, with up to 4.2 mt CO2e/ac emitted at the brackish site and 3.1 mt CO2e/ac emitted at the saltwater site during the first 1.5 years of the study.