Fine-scale habitat selection by two specialist woodpeckers occurring in beech and oak dominated forest in Southern Belgium
Published: Volume 57(2), December 2010. Pages 339-362.
We studied the identification of key habitat parameters for two specialist woodpecker species (middle spotted woodpecker Dendrocopos medius and lesser spotted woodpecker D. minor) associated with mature broadleaved forests ecosystems in Europe, and the modelling of their specific requirements with a view to assist forest managers. The study was conducted in four beech and oak-dominated forests (Haut-Fays, Halma, Gembes and Croix-Scaille) located in the Ardennes Region of Southern Belgium. The study sites covered a total area of ca. 20 km2. A census of woodpecker occurrence (presence absence) was implemented from 2000 to 2003 within 255 1-ha plots. Habitat variables describing stand age, tree density, snag density, stand composition and vertical vegetation structure were also sampled at the same plots to develop both logistic and autologistic regression models describing habitat use. Middle spotted woodpecker (MSW) uses the oak-rich locations (mean basal area of 15.6 km2/ha), with selection of areas with the largest, oldest oak trees (mean circumference > 150 cm), and with a high diversity of tree species in the overstory. Similarly, the lesser spotted woodpecker (LSW) was detected in areas presenting the highest percentage cover of oak trees but with a selection of younger stands, with a high density of snags and dead wood (mean of 9 m3/ha). The integration of an autocorrelation term improved model performance for the LSW but not for MSW. Our results highlight the importance of a high disponibility of oak trees for these two sympatric species. The climax forest in northwest Europe is beech so that public and private owners must develop appropriate forest management plans to prevent the conversion of oak to beech forests. In particular, forest managers can promote an active oak regeneration management to obtain a balanced representation of age classes. They must also aim to maintain/increase the volume of dead wood resources by reserving all trees produced by storms or any other cause of natural mortality.