Bird and beetle assemblages in relict beech forests of central Italy: a multi-taxa approach to assess the importance of dead wood in biodiversity conservation

摘要

The awareness of the importance of deadwood in forest ecosystems has increased in recent decades. Today, dead wood is recognized as a key factor affecting diversity of forest communities. Hole-nesting birds and saproxylic organisms represent an active part of the animal community through the recycle of decaying wood into the forest soils. Three relict beech forests of central Italy were surveyed for both saproxylic beetles and hole-nesting birds, using two different types of interception traps for the former group and point count method for the latter. The variables of dead wood quality were recorded from ten plots, particularly the decaying class and typology of all the wood debris with a diameter >= 5 cm. In order to correlate richness and abundance of beetles and birds in a symmetric way, we used co-inertia analysis (CoIA). To correlate in a predictive way the dead wood attributes (dead wood typology and class decay) with birds and beetles assemblages we used partial redundancy analysis (RDA). Our results showed a significant relationship between saproxylic beetle and hole-nesting bird communities. Three dead wood variables (the volume of standing dead trees, stumps and large branches on the ground) appeared to be good predictors of saproxylic beetle richness while the volume of standing dead tree and of dead trees on the ground were the same for hole-nesting birds. These results suggest specific recommendations useful for forest management and planning.