COMMUNITY STRUCTURE OF ISOPODS (ONISCIDEA) AT DIFFERENT ORCHARDS IN ASSIUT, EGYPT

Terrestrial isopods provide many important services for the ecosystem such as litter decomposition, nutrient mineralization. The present study aimed to make a survey of the distribution of isopods as leaf litter decomposers; in five different orchards during winter and summer and effects of some ecological factors on them. Isopod samples were collected by a tin quadrate sampler (20 X 20 cm.). Some of ecological factors were measured, air and soil temperature, humidity, pH, conductivity, soil water content and organic matter content. In the present study, five isopod species were recorded. Porcellio laevis and Porcellionides pruinosus were eudominant while the other three species were subdominant. P. laevis recorded the highest value of total isopods mean and standard deviation (SD) and that was in site 1. In addition, ANOVA and Duncan comparison showed that total abundance of isopods had no significant difference with the studied seasons but they significantly varied with sites during the whole period of investigation. Species richness and Shannon diversity index recorded their highest values in site 3, then in site 2. The clusters analysis of isopods abundance according to the five studied sites showed that: (a) Leptotrichus naupliensis and Chaetophiloscia hastata were the most similar species in the cluster of isopods abundance. (b) P. laevis was similar to P. pruinosus. Canonical Corresponding Analysis (CCA) of Isopoda and ecological factors revealed that: P. laevi shad positive correlation with air temperature followed by soil water content and soil temperature. Thus, P. laevis and P. pruinosus were the most dominant and abundant species and they both have the ability to live and acclimate with different conditions of the arable fields; of Assiut governorate more than the others. INTRODUCTION