Vegetation and dragonfly fauna — characteristics and examples of biocenological field studies

Abstract

Until now very few biocenological studies have been carried out on dragonflies. This paper describes the various functions of vegetation for Odonata, especially in habitat selection.

It is shown that the two endangered species, Orthetrum coerulescens and Ceriagrion tenellum, due to their dependence on specific abiotic factors, strongly prefer particular plant communities. In selecting suitable breeding habitats, vegetation probably serves as a releasing signal (‘proximate factor’). In contrast, the two species hardly show any clear preference for any of the parameters of the community structure. For the example of C. tenellum the highly selective choice of plant stands and communities is presented in detail. Its ecoscheme may be described as consisting of three main parts, with the vegetation playing a decisive role.

Methodological questions are also discussed. In many dragonfly species the breeding habitats can be described by the plant communities, as well as additional parameters. In conclusion, a step by step procedure for biocenological studies on dragnoflies is proposed.