Ecologische verschillen tussen de Venwitsnuitlibel (Leucorrhinia dubia) en de Noordse witsnuitlibel (Leucorrhinia rubicunda)

Koops, R.-J., D. Schut & D. Groenendijk, 2006. Ecological differences between Leucorrhinia dubia and L. rubicunda. Brachytron 8(2): 3-11. The population trend of Leucorrhinia dubia is negative, whereas the abundance rate of Leucorrhinia rubicunda showed a slight increase during the same period. However, in general both species share the same type of habitat and therefore it was questioned what the reason might be for this difference in abundance rates. The aim of this study was to assess the ecological differences between these two dragonfly species. In total 24 mostly acidic soft water shallow lakes were sampled on Leucorrhinia larvae. Two or more transects were placed in different parts of the pools. From each transect different measurements were taken, like pH, conductivity, water depth, detritus layer and vegetation composition. The results suggest that L. dubia has a smaller pH-range in comparison to L. rubicunda. Both Leucorrhinia species prefer heathland above forest in the direct surrounding of a shallow lake. The vegetation surveys show that both dragonfly species are strongly correlated with the presence of peat moss (Sphagnum sp.). The results also indicates that L. rubicunda has a wider ecological niche than L. dubia. The habitats of both species are acid or slightly acidic, oligo to mesotrophic moorland pools with Sphagnum vegetation; however, L. rubicunda range includes a lower pH. Therefore it may be more resistant to acidification.