ELF ECOLOGICAL MONITORING IN MICHIGAN .3. EARTHWORM COMMUNITY PARAMETERS DURING PRE-OPERATIONAL YEARS

A previous description of the lumbricid communities of the Test and Co ntrol sites of Project ELF is revised and updated, based on 5 full-sea son years of sampling. These 5 years (1984 - 1988) encompass the pre-o perational period of the U.S. Navy's ELF antenna in Michigan, and resu lting data represent a partial foundation for future conclusions regar ding potential effects of ELF electromagnetic fields. Of a total of ei ght species, seven are now known to be common to both sites, only A. l onga remaining unique to the Test community. Annual fluctuations in sp ecies dominance, diversity and equitability are shown to be appreciabl e. Potential sources of error in the derivation of community indices, due either to sampling technique or to problems in immature identifica tion, are listed. Variations in community structure due to the relativ e contribution of species with different life styles are discussed, us ing vertical distribution, habits and population structure as criteria . Year-to-year variations in these parameters are presented. Analysis of horizontal distribution of species is used as indicator of the homo geneity of each study site.