Materials and methods
Site, soil and natural vegetation
The data have been collected from plantings done by the Forest Depart- ment. The sites, selected for the Study, represent typical alkali soil of the semi-arid zone having a mean annual rainfall of 700 mm. About 70% of the rains fall during two months (July and August) and the summer is long. The temperature varies from 4°C in winter to 45°C in summer. The soil is clay-loam and silt which swells when wet and cracks when dry (Fig. 3