This study assesses the value of restoring forested wetlands via the U.S. government's Wetlands Reserve Program (WRP) in the Mississippi Alluvial Valley by quantifying and monetizing ecosystem services. The three focal services are greenhouse gas (GHG) mitigation, nitrogen mitigation, and waterfowl recreation. Site-and region-level measurements of these ecosystem services are combined with process models to quantify their production on agricultural land, which serves as the baseline, and on restored wetlands. We adjust and transform these measures into per-hectare, valuation-ready units and monetize them with prices from emerging ecosystem markets and the environmental economics literature. By valuing three of the many ecosystem services produced, we generate lower bound estimates for the total ecosystem value of the wetlands restoration. Social welfare value is found to be between $1435 and $1486/ha/year, with GHG mitigation valued in the range of $171 to $222, nitrogen mitigation at $1248, and waterfowl recreation at $16. Limited to existing markets, the estimate for annual market value is merely $70/ha, but when fully accounting for potential markets, this estimate rises to $1035/ha. The estimated social value surpasses the public expenditure or social cost of wetlands restoration in only 1 year, indicating that the return on public investment is very attractive for the WRP. Moreover, the potential market value is substantially greater than landowner opportunity costs, showing that payments to private landowners to restore wetlands could also be profitable for individual landowners.

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Delineating wetlands from nonwetlands in seasonally inundated ecosystems is often difficult and requires data on soil functions and attributes. Techniques (including equipment design, construction, and installation) for assessing wetland soil attributes have been developed that allow direct field measurements of soil O2 content, oxidation‐reduction potential, water‐table depth, and presence of ferrous iron. Soil O2 content is measured from diffusion chambers with a specially fitted polarographic probe. Redox potential is measured with permanently installed platinum electrodes and a voltmeter. Determination of water‐table depth may require piezometers in addition to unlined observation wells. The presence of ferrous iron can be detected with α, α,‐dipyridyl and indicates anaerobic conditions, although interpretation and extrapolation of results must be carefully made. These parameters are particularly diagnostic and results of field studies reveal their dynamic nature and utility in wetland delineation efforts.

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This study was conducted at three locations in a bottomland hardwood forest with a distinct elevation and hydrological gradient: ridge (high, dry), transition, and swamp (low, wet). At each location, concentrations of soil greenhouse gases (N 2 O, CH 4 , and CO 2 ), their fluxes to the atmosphere, and soil redox potential (Eh) were measured bimonthly, while the water table was monitored every day. Results show that soil Eh was significantly (Po0.001) correlated with water table: a negative correlation at the ridge and transition locations, but a positive correlation at the permanently flooded swamp location. Both soil gas profile analysis and surface gas flux measurements indicated that the ridge and transition locations could be a sink of atmospheric CH 4 , especially in warm seasons, but generally functioned as a minor source of CH 4 in cool seasons. The swamp location was a major source of CH 4 , and the emission rate was higher in the warm seasons (mean 28 and median 23 mg m À2 h À1 ) than in the cool seasons (both mean and median 13 mg m À2 h À1 ). Average CO 2 emission rate was 251, 380 and 52 mg m À2 h À1 for the ridge, transition and swamp location, respectively. At each location, higher CO 2 emission rates were also found in the warm seasons. The lowest CO 2 emission rate was found at the swamp location, where soil C content was the highest, due to less microbial biomass, less CO 2 production in such an anaerobic environment, and greater difficulty of CO 2 diffusion to the atmosphere. Cumulative global warming potential emission from these three greenhouse gases was in an order of swamp4transition4ridge location. The ratio CO 2 /CH 4 production in soil is a critical factor for evaluating the overall benefit of soil C sequestration, which can be greatly offset by CH 4 production and emission.