Abstract: To find out the effect of the availability of soil moisture on the survival percentage and tree growth in young plantations,a study was carried out in three typical sites on the mid-slopes with different aspects,southerly, westerly and northwesterly, in northern Taihang Mountains.It was found that soil moisture available was ranged -0.3--20 bar,trees grew normally under the status of soil moisture ranged-0.3--3 bar.However,trees would be,slightly or moderately,suffering from water stress as the moisture available reduced to-3--10 bar and-10--20 bar. The results also indicated that the moisture capacity and range of moisture available is the least on the site southwards,on contrast,the largest westwards. The content and availability of soil moisture varied seasonally. Species choice should be considered to use those more resistant to drought for planting programmes, and the soil water conditions could be very much improved by site preparation.

Key words: Soil moisture potential, Moisture availability, Water stress