Keppler et al. (2006, Nature 439, 187–191) showed that plants produce methane (CH₄) in aerobic environments, leading Lowe (2006, Nature 439, 148–149) to postulate that in countries such as New Zealand, where grazed pastures have replaced forests, the forests could have produced as much CH₄ as the ruminants currently grazing these areas. Estimating CH₄ emissions from up to 85 million ruminants in New Zealand is challenging and, for completeness, the capacity of forest and pastoral soils to oxidise CH₄ should be included. On average, the CH₄ emission rate of grazing ruminants is estimated to be 9.6 ± 2.6 g m^–2 year^–1 (±standard deviation), six times the corresponding estimate for an indigenous forest canopy (1.6 ± 1.1 g m^–2 year^–1). The forest’s soil is estimated to oxidise 0.9 ± 0.2 g m^–2 year^–1 more CH₄ than representative soils beneath grazed pasture. Taking into account plant and animal sources and the soil’s oxidative capacity, the net CH₄ emission rates of forest and grazed ecosystems are 0.6 ± 1.1 and 9.8 ± 2.6 g m^–2 year^–1, respectively.