Model comparisons of methane oxidation across a management gradient: Wetlands, rice production systems, and landfill

Through model experiments we quantitatively examined fractional methane oxi dation and net methane emissions using three model systems which encompass a management gradient from pristine (wetlands) to managed (rice production) to highly engineered (landfills). Fractional methane oxidation is rarely d etermined in situ; thus our goal was to cross-compare modeling results and major drivers to field and laboratory data for this important parameter in both pristine and managed systems. In the models, management factors are ty pically introduced as combinations of theoretical relationships, empirical functions, or scaling factors which drive net emissions through forcing of water table variations, availability of degradable organic carbon substrate s, input and cycling of major nutrients, variability in plant communities, physical properties for gaseous transport, and indigenous capacity of soils for methane oxidation. The net methane emission and fractional oxidation v ary by orders of magnitude within and among the three model systems, yet ea ch model was quite consistent in its predictive ability. This study lays th e groundwork for a more unified, modular approach to modeling methane emiss ions from soil sources where both natural (climatic and ecological) and ant hropogenic factors are important drivers.