Dragonfly (Odonata) distribution patterns in urban and forest landscapes, and recommendations for riparian management

Odonata species are particularly sensitive to human disturbances. Their diversity relative to four landscape types (plantation forest, parkland, residential area, industrial area) along a small river (the Dorpspruit) that runs through Pietermaritzburg, South Africa, is described. Individual species-environment relations were investigated using the multivariate analysis package CANOCO. Four biotope types were identified and characterised. The analysis also illustrated the extent to which the urban, suburban and forestry environments affected the Odonata species. Multispecies assemblages were good environmental indicators. Individual indicator species included Chlorolestes tessellatus and Crocothemis erythraea. Chlorolestes tessellatus is a good indicator of the minimal width (>30m) of the indigenous strip of riparian vegetation between the stream edge and commercial plantations. This study suggests that there should be a riparian strip between the water's edge and plantation trees of at least 20 m (prefarably 30 m). This finding is integrated with earlier ones to arrive at a general conservation management recommendation, at least for dragonflies, for rivers in South Africa.