Altitudinal Variation of Oniscidean Communities on Cretan Mountains

Abstract

In the present paper we present a study on the effect of geographical elevation on the communi- ties of terrestrial isopods. We analysed the patterns of species diversity and the phenology ofOnis- cidea species in successive altitudinal zones on the three high mountains of the island of Crete (Greece) using monthly sampling with pitfall traps for one year. The results are compared with similar data from other mountains in Greece. Species richness decreases gradually till the timber- line and very few species are able to survive higher, in the sub-alpine and alpine habitats. The phenology of the species reveals the shortening of the biological year on high altitudes and is re- lated with the altitudinal exploitation range of the species. Some biogeographical problems con- cerning the species assemblages of the mountains are also discussed.