Hierarchical analysis of mite community structures in Irish forests-A study of the relative contribution of location, forest type and microhabitat

In determining the overall γ-diversity within a land use type or when assessing the impact of a land use on biodiversity one has to consider the hierarchically nested nature of the γ-diversity. In this study we used a hierarchical approach to examine the diversity of mites, Oribatei and Mesostigmata, in various forest types in Ireland. The study included sampling at regional, stand, individual tree and microhabitat scales. α- and β-diversity (species richness) was examined at each of these scales and the proportional contribution to the variation accounted for by each level of the hierarchy was quantified. β-Diversity generally accounted for at least 50% of the γ-diversity at all levels of the habitat hierarchy with average values varying from 34% between regions, to 57.5% between forest types within region, to 63% between trees within forest type and 63% between microhabitats within a forest type. Differences between the fauna of microhabitats within a forest type accounted for approximately 30% of the total variation while that of forest types within regions accounted for 10.5%. These results are similar to those reported in several other studies but the study quantifies the variation by examining the relative contributions of α- and β-diversity to species richness. Redundancy Analysis allowed the identification of the proportional contribution of the hierarchical components to the variation in community structure in a manner which has not been used before for these systems.