Some of the rarest European saproxylic beetles are common in the wilderness of Northern Mongolia

Natural landscapes characterized by heavy disturbance regimes were displaced in Europe by managed cultural landscapes over the past centuries. The associated loss of biological legacies, such as dead or dying trees, has exposed numerous saproxylic species to high risks of extinction. In contrast, extensive wilderness forests in Northern Mongolia have been sustained owing to significant cultural differences. Here we used saproxylic beetle abundance data gathered during two sampling campaigns in the Mongolian taiga to address whether (1) the saproxylic beetle fauna of the Mongolian taiga is comparable to that of European boreal forests, (2) fires are a natural disturbance regime, indicated by the occurrence of many pyrophilous species, and (3) species rare in Europe are also rare in the Northern Mongolian wilderness. Of 191 saproxylic beetle species identified, 150 (79 %) were also found in Europe. The high number of pyrophilous beetle species (20) indicated that natural species communities are well adapted to this disturbance regime. The species rarity in Germany was significantly positively correlated with the species rarity in Finland, but the species rarity in these two countries was negatively correlated with that in the Mongolian wilderness. Our results indicated that wilderness areas with natural disturbances provide biological legacies important for rare species. Therefore, exploitation of the unique, remaining natural landscapes of the Palaearctic wilderness areas should be stopped. Moreover, we urge conservationists to expand controlled burning for restoration at relict sites of rare boreal species also outside Fennoscandia.