Changes in oribatid faunal structure associated with land conversion from annual crop into orchard

The main goal of the present study was to test the effect of converting lan d from annual crop to orchard on the ecology of certain soil inhabitants. I n this study samples were collected once every season (summer, autumn, wint er and spring) from two adjacent plots of distinct plant cover (i.e. annual crop and orchard) at Abu Mashour village, Berket El-Saab, Menoufia Governo rate, Egypt. The field had originally been cultivated with annual crops for around fifty years. Ten years ago, a large area of the field was displaced by orchard. The community composition of soil arthropods was determined th roughout the period of study. The obtained results revealed that some speci es were not influenced by plant substitution e.g. Scheloribates laevigatus, Xylobates capucinus and Lamellobates h. aegypticus. Three other species ha d a positive response towards plant substitution e.g. Rhysotritia a. ardua, Lohmannia turcumanica and Striatoppia papillata and some species had a neg ative response e.g. Javacarus kuehnelti, Scheloribates pallidulus and Rostr ozetes foveolatus. In the new situation (orchard), some oribatid mites incr eased their dominance in the community, others exhibited a decrease of domi nance. The oribatid population density in the orchard habitat increased by about 44% in comparison with the annual crop site. Fecundity is not conside red as a useful parameter to study changes in dominance. It is suggested th at Lohmannia turcumanica and Zygoribatula dermatoglypha could be used as a sensitive parameter and useful test species for plant substitution. In conc lusion, the annual crop-orchard substitution has a beneficial effect on soi l inhabitants and oribatid mites respond clearly to plant cover.