Abstract:Based on a survey of the major trees grown on oil shale residue in Maoming, Guangdong, three species, (Vatica mangachapoi, Ormosia pinnata, and Khaya senegalensis) were chosen from 35 tree species for further study of their adaptation to such environment. The results showed that the net photosynthetic rates of the 3 species were significantly different, with a ranking of K. senegalensis> O. pinnata > V. inangachapoi. Diurnal variations of net photosynthetic rate in K. senegatensis and O. pinnata were great while that in V. mangachapoi was less. The ranking of their stomatal conductances was K. senegalensis > O. pinnata > V. mangachapoi. The difference in net photosynthetic rate among the three trees was related to the stomatal conductance. Though the net photosynthetic rate in K. senegalensis was higher, its intrinsic water use efficiency was lower than that in O. pinnata due to more water loss. The intrinsic water use efficiency of V. mangachapoi was much higher in the afternoon because of the lower stomatal conductance. The results indicate that K. senegalensis and O. pinnata might be more adaptable to the special environment.