الفهرس 
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Abstract
Soils of the world are usually abound with active individuals representing a multitude of microbial and invertebrate taxa. Now- adays, humans are aware of the existence of such cryptic life forms. These soil biota are organized both structurallY and functionally into specific microcommunities. Such organized microcommunities are modified by human activities with the degree of modification being dependent on the nature, intensity, and longevity of human disturbances. In disturbed soils, as well as undisturbed ones, the types and numbers of soil organisms and their specific functions reflect the pedogenic status, vegetative successional patterns, and environmental perturbations of given sites (Dindal, 1990) . Most of the soil ecological studies revealed that the invaluable role played by the soil organisms - bacteria, actinomyceies. fungi, algae, protozoans and invertebrates - includes the dynamic decom- position of organic matter and production of humus, cycling of nutrients and energy, elemental fixation, soil metabolism, and production of complex compounds that cause soil aggregates (HAgvar. 1988 and Pokarzhevskij et al .. 1989). Hill (1985) stated that all soil animals have beneficial effects on soil structure and fertility . Many soil microorganisms are functionally related in a symbiotic way to plants and animals forming the essential bases of the hetero- trophic microcommunities that dominate the soil ecosystems (Hudson, 1965; Stotzky. 1972; Dindal. 1985 and Stevenson & Dindal. 1987).