The role of topography, stand and habitat features for management and biodiversity of a prominent forest hotspot of the Mediterranean Basin: Saproxylic beetles as possible indicators

The maintenance of biodiversity in forestlands has become one of the major concerns of global forestry. Regarding the situation of Italy, the Mediterranean forests belong to the less studied in Europe. There is an urgent need to individuate reliable indicators that help to assess forest features important for their future management and biodiversity. We focused our study on the largest forest hotspot of Southern Italy, the Sila National Park in Calabria, an upland covered by 130,000 ha of forest dominated by Calabrian black pine (Pinus nigra calabrica). We chose to test saproxylic beetle species as possible indicators of biodiversity and management. The main condition was the use of method and species useful also for forest managers. Data on the occurrence of 75 wood-inhabiting beetle species of body size approx. 1 cm and larger have been collected in 2010–2015 at 96 forest sites by multiple methods finally simplified in standardized visual census. For the suitability of individual species for indication, we used a novel hierarchical approach: starting from a model for the whole community. Target species were selected if they occupied more than 20% of the sites and non-obligate saproxylics were eliminated. These species’ responses were compared with that of the whole community and only concordant species were maintained as possible indicators. Species whose presence marked significantly species-rich habitats have evaluated as biodiversity indicators. Finally, conservation value model was used for validation. Two saproxylics met all the stepwise criteria used: Cucujus cinnaberinus and Clinidium canaliculatum. They provide a simple and useful tool for periodic diversity monitoring in nature reserve networks. Choosing easily identifiable species, rapidly detectable in a visual census as biodiversity indicators may greatly facilitate less expensive forest monitoring also by unspecialized forest managers.