The Dragonfly Association Index (Insecta: Odonata)a Tool for the Type-Specific Assessment of Lowland Rivers

Species traits of 57 Odonata species occurring in the Austrian bioregion Eastern Ridges and Lowlands (ecoregion Hungarian Lowlands; Illies, ) were defined by factor loadings of 12 habitat parameters: stream sections crenon, rhithron and potamon; flow velocity; standing water; temporary water; size of water body; open water; open banks; submerged macrophytes; reed; and riparian trees. On the basis of the species-specific configurations of these habitat parameters, cluster analysis revealed seven dragonfly associations with different habitat needs: association of open waters, association of sparsely vegetated banks, association of reed and riparian trees, association of reed and submerged macrophytes, association of temporary waters, rhithron association and potamon association. Correlations between the associations' habitat requirements and the habitat parameters of the seven (near-)natural river types, which are present in this bioregion were performed to define river type-specific association compositions. From these results, a dragonfly association index was created to assess the ecological status of these rivers within the five-tiered system of the European Union Water Framework Directive, emphasizing hydro-morphological aspects by comparing the type-specific reference situation with the actual status quo of dragonfly colonization. The method was applied at different rivers, particularly for the purpose of evaluating restoration measures. Copyright (c) 2014 John Wiley & Sons, Ltd.