Methane flux of leaves in a tropical rainforest and a temperate conifer forest

Abstract

We measured methane (CH[4]) fluxes of leaves growing in a tropical rainforest and a temperate conifer forest using the closed static chamber method. Leaf samples were chosen from the canopy and forest floor of a tropical rainforest at Pasoh Forest Reserve, Peninsular Malaysia and a temperate forest at Kiryu Experimental Watershed (KEW), central Japan. At Pasoh, we sampled four species from the canopy (Xanthophyllum stipitatum, Dipterocarpus sublamellatus, Ptychopyxis caput-medusae, Neobalanocarpus heimii) and four species from the forest floor (Alphonsea maingayi, Rinorea anguifera, Macaranga lowii, Neobalanocarpus heimii). The leaves of Elaeis guineensis were also sampled at an oil palm plantation near the forest reserve area. At KEW, we sampled the leaves of Chamaecyparis obtusa, from both the top (18 m) and middle (16 m) of the canopy as well as leaves of Eurya japonica at the forest floor. Incubation experiments revealed that CH[4] was emitted from leaves of the tested species sampled at two sites, although CH[4] fluxes showed variations on a daily basis. These results suggest that tree leaves both at Pasoh and KEW might function as a small CH[4]source, but their contribution to the CH[4] exchange of the total forest ecosystem is very small compared to the soil CH[4] flux