SEASONAL-CHANGES IN THE DISTRIBUTION AND ABUNDANCE OF ISOPOD SPECIES IN DIFFERENT HABITATS WITHIN THE MEDITERRANEAN REGION OF NORTHERN ISRAEL

Mediterranean isopod distribution and abundance were studied in four h abitats: in pine forest, oak woodland and two grasslands. Eleven speci es were identified. Six of them were particularly abundant: Porcellio ficulneus, and Armadillo sp. (''brown'') were typical of grasslands, S chizidium tiberianum was also most abundant there, although it was fou nd in other habitats as well. Armadillo officinalis proved to be a cha racteristic species of woodlands. Chaetophiloscia spp. (the complex co ntains three species, which co-occur in the same habitat and they can be distinguished by their males only) and Porcellionides pruinosus wer e abundant in all types of habitats studied here. Isopod species diver sity [H(S)] ranged between 1.14 and 2.07 being highest in the climax p lant association of the oak woodland. Decreasing numbers of specimens reflected mainly seasonal changes during spring time due to dry condit ions. The most abundant species were, at the same time, the largest in size or body mass and constituted the bulk of isopod biomass (P. ficu lneus and A. officinalis). The total biomass ranged between 18.3 and 1 86.4 mg/m(2) in the different habitats during the two seasons.