DISTRIBUTION OF FOREST DWELLING CARABIDS (COLEOPTERA) - SPATIAL SCALEAND THE CONCEPT OF COMMUNITIES

Associations between spatial distribution of ground-beetles (Carabidae ) and environmental variables were studied over three hierarchical sca les in deciduous forest in central Alberta, Canada. We also examined t he relationship between species abundance and distribution on several scales ranging from the local scale of our study to that of the North American temperate deciduous forest. Understorey plant cover, tree cov er, and occurrence of other carabids were associated with distribution of particular species at the smallest ecological scales within popula tions. However, great differences in population sizes of carabid speci es among five distinct sites several kilometres apart were not correla ted with variation in the same environmental variables. In central Alb erta, abundance and extent of distribution were correlated positively among the 30 carabid species collected, and distributions of the ten s pecies classified as 'core' species were generally aggregated at all s patial scales. On the continental scale, there was a significant posit ive correlation between abundance and distribution for the 114 species of the entire data set, and the six species meeting the criteria of ' core' taxa on this scale, were also 'core' elements in central Alberta . Further analysis of covariance of core elements of species assemblag es across different taxa provides a sound empirical approach for under standing community organization.