Methane flux in Peltandra virginica (Araceae) wetlands: comparison of field data with a mathematical model

We present a mathematical model of the diffusive flux of methane through Peltandra virginica. Data on the diurnal changes in both the petiolar [CH 4 ] gradient and the values of the radial bulk exchange coefficient, E r , are entirely consistent with this model and the assertion that changes in stomatal conductance regulate the rate of methane efflux in P. virginica. The differences between the values of E r calculated for daytime and nighttime conditions are ‐40% for the submerged condition and ‐54% for the emergent condition. The axial diffusivity of CH 4 through the petiole of P. virginica is estimated in vitro to be 0.771 cm 2 min ‐1 . Using our model, we estimate the equilibrium rate of methane efflux under daytime (97 ng CH 4 min 1 petiole ‐1 ) and nighttime (65 ng CH 4 min ‐1 petiole ‐1 ) emergent conditions. Numerical solutions of the model equations in the time domain offer a way of providing a dynamic model of the gas exchange responses of P. virginica to changing environmental conditions.