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Water availability and nutrient limitation are the most important driving forces in hot desert ecosystems, determining vegetation cover and biological activity. In this study the amoeba population was determined in the upper soil layer (0-10 and 10-20 cm) under and between 4 individual Zygophyllum dumosum shrubs. The soil samples were taken from the different layer beneath the shrub and between the shrubs (control) along four seasons. Total number of amoeba was significantly higher in the Z. dumosum root canopy (2935 individual/g soil) in comparison to control samples (625 individual/g soil). Amoebal density was highest at 10-20 cm during the winter, spring and summer. In autumn, during heavy dewfall amoebal density was greatest in the top 10 cm of soil. (C) 2004 Elsevier GmbH. All rights reserved.