TERRESTRlALECOSYSTEM AND SOME ECOLOGICAL VARIABILITIES

Abstract

Soil fauna investigations began very recent in Egypt according to the importance of these organisms to soil, especially mites, one can summarize its importance in brief as follows: 1- Soil microfauna and especially mites and collembola serve as organic degradators in soil, that leads to soil fertility, the same way as earthworms do. 2- Some soil mites especially oribatids act as intermediate hosts: i.e.: Cestods especially some tapeworms of the genus Monizia are pests for important farm animals such as sheep and cows. 3- Some soil-mite groups act as parasites and predators, and therefore, they are important organisms from a biological point ofview, i.e.: family Cheyletidae, Pachylealapidae .... etc. 4- Studies indicated that some soil mites nourish on special injurious soil fungi and bacteria. 5- Most investigations indicated that soil mites are important factors in nutrient

cycling.

6- Many investigations indicated the importance of soil mites in being used as indicators to soil type, however, soil arthropods in general have the potentional of being excellent indicator species, because of their relatively short life history and limited tolerance to changes in environmental conditions. 7- Some soil arthropodes especially mites and collembolans may be a nuisance to man, especially those species that penetrates homes. Thermites and some ymenopterus species may cause structural damage to buildings,and some dipterous species are important for reasons of public health and preventive medicine. 8- Soil arthropods in general and soil mites in specific, are excellent organisms to s dy genetics, physiology, ecology and evolution. Some arthropod classes such as mites and collembolans show great diversity of species, and numbers is closely integrated ecosystems. Soil Arthropods are readily accessible materials throughout the year to any University classroom.