Effects of structural and deadwood attributes on the abundance of saproxylic beetles and microhabitats in a silver fir forest, Italy.

We described the forest structural attributes, deadwood characteristics and microhabitats occurrence, evaluating their role on the abundance and distribution of saproxylic beetle fauna. The study was realized in Central Apennines (Italy), in a silver fir stand that has been unmanaged since several decades. A systematic aligned sampling method was realized on 240 ha, examining 50 plots. Data were collected to assess forest structural parameters, microhabitats and deadwood volumes. Saproxylic beetles were sampled using window flight traps and emergence traps; the link between structure-based indicators and saproxylic species was then analyzed. Geostatistical analyses were conducted for highlighting the spatial variability of the parameters investigated and the beetle pattern distributions. With the aim of describing the complex saproxylic ecological network, the species of beetles were classified according to the type of interactions with wood and other insects and to trophic levels. Results showed how the saproxylics are influenced by the deadwood amounts, size and decay, but also by the forest complexity and microhabitats. The results implied the importance of deadwood traits and microhabitat amounts as monitoring tools for preserving biodiversity. New indicators, such as microhabitats, should be implemented in the traditional forest inventory approaches as a measure of nature conservation.