Possibility of avoiding legumes-deriving boost of N 2 O emissions in tropical monoculture tree plantations

Recent reports warned that planting leguminous trees under monocultures elevates nitrous oxide(N2O)emissions through N-rich litter inputs.We hypothesized that planting trees on sandy soil can avoid the legume-derived boost of N2O emissions through limiting water availability for N2O production.Effects of planting legumes on methane(CH4)uptakes were also examined.N2O emissions and CH4uptakes were compared among five tropical tree plantation stands including three leguminous stands(Acacia auriculiformis,Acacia mangium,and Xylia xylocarpa)and two non-leguminous stands(Eucalyptus camaldulensis,and Hope a odorata).Due to lower water contents of the soil,the N2O fluxes in our study site were at the lower end of the tropical rain forests.As we hypothesized,no clear differences in N2O emissions were obs erved between leguminous and non-leguminous stands.CH4uptake rates in the present study were lower than those of other tropical forests.CH4uptakes in leguminous stands did not differ from those in non-leguminous stands.Overall,we demonstrated that planting leguminous trees on sandy soils has a potential to enable us to manage leguminous monoculture tree plantations without boosting N2O emissions or reducing CH4uptakes.