Guidelines for the monitoring of Morimus asper funereus and Morimus asper asper

Morimus asper is a morphologically variable longhorn beetle that occurs in large parts of southern and central Europe. Although this saproxylic beetle is widespread in old-growth forests or well-structured woodlands, its populations are currently threatened by forest practices, such as the removal of wood (branches and logs). Morimus funereus is considered a valid species by some authors and is included in Annex II of the Habitats Directive. However, a recent molecular study found that all European and Turkish populations should be referred to a single species, M. asper. In this paper, the monitoring methods proposed for M. asper (sensu lato) in the various European countries are reviewed and the research carried out in Italy, which was aimed at developing guidelines for its monitoring, is presented. The experiments conducted, mainly with log piles built from freshly cut wood, investigated, amongst other things, the importance of wood type, diameter of logs and age of wood for the number of individuals observed. Based on these results and on a literature review, a detailed monitoring method for M. asper is proposed here, together with a discussion on its constraints, spatial validity and possible interferences. In order to facilitate the assessment of the conservation status of populations of M. asper and to allow for comparisons between populations and over time, a method for the calculation of a reference value, based on the monitoring method, is also presented.