Abstract:The CH4 and N2O fluxes from soil surface of different land use in a hilly area of South China were examined from 2004-03-30 to 2005-07-27. CH4 and N2O fluxes were measured with closed static chamber and a modified gas chromatograph (HP5890Ⅱ) in situ in two different land-use types: plantation mainly composed of Pinus massoniana and orchard of Dimocarpus longan, respectively. There were two sets of plots at both sites respectively: ones were covered with litters on the surface soil and the others without litters. The annual average CH4 fluxes from plot with litters were -3.41±0.3 kg CH4 hm-2a-1 in the pine plantation and -3.24±0.44 kg CH4 hm-2a-1 in the orchard; annual average N2O fluxes were 4.57±0.50 kg N2O-N hm-2a-1 and 11.99±0.67 kg N2O-N hm-2a-1, respectively. The annual average CH4 fluxes from plot without litters were -2.98±0.44 kg CH4 hm-2a-1 in the pine plantation and -1.93±0.53 kg CH4 hm-2a-1 in the orchard; annual average N2O fluxes were 3.12±0.28 kg N2O-N hm-2a-1 and 9.42±0.56 kg N2O-N hm-2a-1, respectively. N2O fluxes from soil surface were closely related to the types of land use. They were significantly higher from orchard than those from pine plantation (P<0.01). CH4 absorptions were higher in dry season (October~March) and lower in rainy season (April~September). N2O fluxes were higher in rainy season and lower in dry season. The results indicated that CH4 and N2O fluxes from soil surface were affected by soil water content more than temperature. CH4 absorptions were affected little by litter removal. The litter decomposition accounted for 31.71％ and 21.40％ of the total N2O emissions from the pine plantation and from orchard soil surface, respectively. The result also indicated that there was a dominant driving effect of precipitation on the N2O flux from soil surface in rainy season.
