Libellen in noordwest-Vlaanderen: status, belang en behoud

The odonatofauna of the north of the province West-Flanders (Belgium) is relatively well-known. This article deals with historical and recent distribution of observed species (31 in total) and aims to determine the most important sites (species diversity, rarity) for dragonflies. Sites were clustered in respect to species composition using TWINSPAN software. Division levels were then displayed in a GIS-environment, so as to get an idea about the usefulness of the current ecodistricts in intrepreting distribution patterns of dragonflies in the region. The Houtland ecodistrict, a region of pleistocene sands, appeared most species diverse, with the Bell Heather Reserve fen (Zevenkerke) displaying the highest species richness in the region (22 species). No less than three Red List species were recorded in this district, the latter probably being extinct: Cordulia aenea, Leucorrhinia dubia and Coenagrion pulchellum. The ecodistrict “dunes” is important for the vulnerable Ischnura pumilio. It is suggested that ecodistricts might be too detailed for interpreting dragonfly distribution. Finally we present ideas for maintaining and managing populations of some delicate species.