Abstract: Based on the measurements of the diurnal and monthly transpiration rate, the characteristics of transpiration of Caragana korshinskii Kom and Sophara viciifolia Hance and the relationship between transpiration and environmental factors and soil water were studied. The following conclusions can be drawn: the curves of the diurnal variations of transpiration rate in Sophara viciifolia Hance and Caragana korshinskii Kom show one-peak type mainly, their highest transpiration rate occurred in period of 10: 00~14: 00;The transpiration rate of Sophara viciifolia Hance and Caragana korshinskii Kom decreases gradually from June to September, there is no big difference with the average value of monthly transpiration among the different age's Sophara viciifolia Hance, but the transpiration rate of Sophara viciifolia Hance is higher than Caragana korshinskii Kom from June to September;the curves of diurnal variation of transpiration rate in Sophara viciifolia Hance has a positive correlation with PAR and air temperature and has a negative correlation with air humidity;the seasonal changes of transpiration rate has a close relation with the content of soil water. As a result, we should know the plant's water-consumption and the ability of soil' s water supply in the process of vegetation reconstruction in the hilly and gully loess area to ensure the vegetation restoration.

Key words: Sophara viciifolia Hance, Caragana korshinskii Kom, transpiration, environmental factors