Abstract
Survival and establishment of range plant seedlings is mostly dependent on the amount and distribution of rainfall. Little is known about survival and establishment of range plants native to Saudi Arabia. The aim of the study was to investigate the effect of amount of rainfall (100, 200 and 400 mm) and rainfall distribution (7 and 14 days between two rains) on seedling survival and establishment three populations of Hammada elegans from different areas in Saudi Arabia. Water equivalent to the specified amounts of rainfall was evenly distributed every 7 or 14 days over a period of three months. Seedlings were then left td grow for another two months without irrigation. The results showed that survival and establishment under 400 mm rainfall were significantly higher than the other two rainfall averages (47% and 11% respectively). Survival percentage increased as the period between two rains was extended to 14 days although not significantly. Establishment increased from 3% to 9% with extention of period between two rains. No significant differences were observed among the three populations. These results indicate that successful establishment of H. elegans may be expected in lower lands where rain water is collected from surrounding areas and that seedling establishment may be encouraged as the period between two effective rains is extended.