Sampling season affects conclusions on soil arthropod community structure responses to metal pollution in Mediterranean urban soils

This study aimed to assess if the period of sampling affected conclusions on the responses of arthropod community structure to metal pollution in urban soils in the Mediterranean area. Higher temperature and lower precipitation were detected in autumn than in spring. In both samplings, the most abundant taxa were Acarina and Collembola, although their relative abundances were differently affected by seasonality and metal contamination. The relative abundance of Acarina was higher in autumn and positively related with soil total Cu, whereas Collembola abundance was higher in spring and correlated with water-extractable Cu. Arthropod community was heavily affected by seasonal variations in climatic conditions in high and low polluted soils, showing for the same soil different responses dependent on the sampling season. Sampling time therefore is a fundamental factor when assessing the effects of metal pollution on soil arthropod communities.