Distribution of forest dwelling carabids (Coleoptera): spatial scale and the concept of communities

Associations between spatial distribution of ground-beetles (Carabidae) and environmental variables were studied over three hierarchical scales in deciduous forest in central Alberta, Canada We also examined the 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 cover, and occurrence of other carabids were associated with distribution of particular species at the smallest ecological scales within populations However, great differences in population sues of carabid species among five distinct sites several kilometres apart were not correlated with variation in the same environmental variables In central Alberta, abundance and extent of distribution were correlated positively among the 30 carabid species collected, and distributions of the ten species classified as 'core' species were generally aggregated at all spatial scales On the continental scale, there was a significant positive 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 assemblages across different taxa provides a sound empirical approach for understanding community organization