Abstract: This paper firstly measured in situ N₂O emission from branches and leaves of sun plants (Fraxinus mandshurica,Pinus koraiensis,Alnus hirsuta) and shade tolerant plants (Tilia amurrensis) under different light irradiances in closed chamber. Light irradiance had contrast effects on N₂O emission flux from sun and shade tolerant tree species. In the test sun plants,more N₂O was emitted under weak light than under strong light. The emission rates decreased with increasing irradiances,and even absorption instead of emission of N₂O was detected under strong light. In contrast to sun plants,in the shade tolerant plant T.amurrensis,there was more N₂O emission under strong light than under weak light,and N₂O absorption from environment was detected under weak light.

Key words: Light irradiances, Sun plant, Shade tolerant plant, N₂O emission, vegetation index, MODIS reflectance, Back Propagation neural network, bamboo forest, leaf area index