ELF Communications System Ecological Monitoring Program: Soil Arthropods and Earthworms

Based on analysis of years grouped by pre-ELF and operational periods, density fluctuations of arthropods (Collembola and mites) were, in some taxa, significantly different between sites; in others, differences between year groups were significant within either of the study sites. No consistent patterns were seen at the level of species or higher taxa. In some species, effects of the 1988 drought may have carried over into 1989, the first year of antenna operation. Surface-active Collembola, velvet mites and carabid beetles did not alter their activity patterns following antenna activation (e.g., species predominantly spring-active remained spring-active). Although analyses routinely yielded significant differences with respect to total numbers captured -in Test and Control, numbers alone were found to be unreliable estimators for disturbance, because a variety of potentially important factors other than EM fields were present. Weekly changes in relative numbers captured, however, showed that increases and decreases in activity were synchronous in the study sites. Carabid beetle activity, which is highly seasonal and governed mainly by reproductive processes, was not affected by EM fields.