Study On Water Consumption Characteristics Of Atraphaxis Bracteata And Hedysarum Scoparium In Mu Us Sandy

In view of the status of water shortage in the arid and semi-arid areas, aimed at suppling a theoretical basis for the vegetation construction, the paper studied transpiration characteristics and the relationship with the main factors of two common shrub species Atraphaxis bracteata and Hedysarum scoparium of the Mu Us sandy,in 2009. The main research results are as follows:Diurnal variation of sap flow fluctuation is basically consistent, it started at 7:00-7:30, at 9:00-11:00 peak appears, Atraphaxis bracteata showed unique "lunch break" phenomenon, but Hedysa-rum scoparium not. Since then, the sap flow keep a high value, after 19:00 it began to decline rapidly, till 20:00 it's drop down to extremely low and remained relatively low flow all night.The accumulation of fluid was increased with the stem diameter increases. In growth season (From May to Oct.), the Atraphaxis bracteata water consumption was 82.63 kg/m2, and Hedysa-rum scoparium was 68.09 kg/m-2. Compared with other species research, the water consumption of Atraphaxis bracteata and Hedysarum scoparium were significantly smaller, so we can give priority to these two plants in sandy afforestation.The main environmental factors which affected the transpiration were solar radiation, air temperature, relative humidity and wind speed, the multiple linear regression equation between the flow rate and the surrounding factors was established as follows:V Atuphaxis bracteata =123.711+0.249Re-1.243X2 (R2=0.756), V Hedysurum scoparium=89.079+0.073Re-0.636RH-8.588Vw(R-=0.732).The vertical distribution of soil moisture content of Atraphaxis bracteata and Hedysarum scoparium plot can be divided into 3 layers:The rapid change layer, active layer, the stable layer; in accordance with the growing season, soil moisture of every plots can be divided into the following stages:May,Sep.,Oct. of water loss stage; June and July were consumption stage and supply stage on August. Because of abundant precipitation in 2009, the surplus of soil moisture of every plots, which Atraphaxis bracteata woodland surplus 12.76mm, Hedysarum scoparium woodland surplus 12.31mm.During the grouth season,form May to October,water consumption amount of Atraphaxis bracteata and Hedysarum scoparium plot was respectly 11.33mm,28.83mm,35.96mm,37.78mm, 30.30mm,26.51mm,and 10.62mm,21.01 mm,23.25 mm,32.73 mm,25.64mm,14.37mm.