The great capricorn beetle Cerambyx cerdo L. in south-western Poland – the current state and perspectives of conservation in one of the recent distribution centres in Central Europe

Abstract

Presence-only models can aid conservation and management of threatened, elusive species. A MaxEnt model has been developed for the great capricorn beetle (Cerambyx cerdo L., 1758) in south-western Poland and the variables identified best explaining the species’ occurrence on a large scale. Once successfully validated, the model was used to (a) illustrate the expected location of the species’ habitats in the region and in existing Natura 2000 sites (SACs) in S-W Poland and (b) assess the efficacy of the regional network of national protected areas (NPAs) versus Natura 2000 (SACs). Overall, information was gathered on 1025 localities of C. cerdo L., 1758 in Lower Silesia. All the records came from the pedunculate oak Quercus robur L., 1753. The occurrence of the great capricorn beetle in the study region is limited mainly to its eastern part, with a marked concentration in the valleys of the rivers Odra, Barycz and Bystrzyca. The kernel density estimation analysis also showed the high concentration of occupied trees in the north-western part of the region, clearly isolated from the above-mentioned main populations. Although a considerable part of the localities in the study region (74.2%) occurred within protected areas (PAs), their contribution to the species’ conservation varied between the PAs groups. Natura 2000 SACs are the most important PAs, covering more than 30% of the predicted area of suitable habitats in the region and more than 45% of optimal habitats. In total, 384 localities of C. cerdo L., 1758 were found within the cities, most of them (n = 356) in the city of Wrocław. Forty three percent (43%) of the urban localities of the species (n = 165) in the study region are protected within the regional network of protected areas (OPAs), while those unprotected are mainly concentrated in the city of Wrocław (n = 207). Wrocław also includes 17.1% of the area of suitable habitats and 29% optimal habitats of the species in the region outside the protected area network. To preserve C. cerdo L., 1758, forest corridors should be created or restored to bridge the otherwise impermeable gaps revealed by the authors’ model and grant protection to the still largely unprotected area of the Lower Silesian territory. The species conservation programme in the region requires the cooperation of various authorities, not only those dealing with nature conservation, but also local governments, state forest management and flood protection authorities.