[Objective] To study the drought tolerance of three afforestation trees on the sandy shores of Northern Jiangsu Province.[Methods] Based on the experiment of water stress in pots

the index variation of water physiological characteristics and daily dynamics of photosynthetic characteristics of 2-year-old Zelkova schnideriana

Quercus virginiana and Ligustrum lucidum under water stress were analyzed.[Results] (1) With time and stress intensity increasing

the relative water content in leaves of the three tree species all decreased

and the decreasing range of Zelkova schnideriana was bigger than that of Quercus virginiana and Ligustrum lucidum; water content of the three tree species decreased by 78.8%

61.9% and 65.5% under severe water stress of 58 days

and the relative water contents of Quercus virginiana and Ligustrum lucidum changed a little. (2) Under treatments of CK

60% and 45% water content

the diurnal curves of the photosynthetic rate of the three tree species were "double-peak". Under normal and light water stress

the diurnal curves of the transpiration rate and stomatal conductance of Quercus virginiana were "double-peak"

while the same curves of Zelkova schnideriana and L igustrum lucidum were "single-peak". With increasing stress

the order of Pn

Tr

Gs and WUE of the three tree species was:CK>60% water content>45% water content>30% water content. In the same soil water grades

the daily averages of the four indexes of Zelkova schnideriana were relatively small

followed by Ligustrum lucidum

whereas those of Quercus virginiana were the largest.[Conclusion] The drought tolerance characteristics of Zelkova schnideriana were relatively small

followed by Ligustrum lucidum

whereas those of Quercus virginiana were the largest.