Abstract: Employing LI-6400 photosynthesis system (LI-COR,1995,USA),this paper studied the gas exchange,water consumption,and water use efficiency of Populus alba×berolinensis seedlings under different water supply.The results showed that among test environmental factors,soil moisture content was the dominant one affecting seedlings transpiration.The water consumption of the seedlings decreased with increasing drought stress,but the effects of meteorological factors were not obvious when soil moisture content was lower than 50% of field capacity.P.alba×berolinensis seedlings could grow well when soil moisture content was higher than 70% of field capacity.

Key words: 3S techniques, Ecological landscape planning, Principal analysis, Digital elevation model