Improved method for comparing abundance data for soil zoological field studies

Soil bulk density varies among sites as well as microhabitats, and in diffe rent years at the same site. Bulk density is a highly variable parameter th at introduces undefined but significant errors to abundance field data of s oil microfauna when given in individuals per g soil dry mass (sdm). Such da ta are not comparable among sites, microhabitats and years and they are uns uitable for comparative ecological field studies. Soil corer sampling techn ique, defined as soil surface square units (e.g. 1 cm(2)), is recommended t o overcome the methodological imprecision of estimating abundance of soil m icrofauna from field studies in ind.g sdm. This removes consideration of va riable soil bulk density and enables us to establish abundance values direc tly in ind.cm(-2) without any recalculations. Resultant data are comparable both spatially and temporally. Abundance data as individuals per m(2) is a commonly used unit for soil meso-, macro- and megafauna. (C) 2000 Editions scientifiques et medicales Elsevier SAS.