Management tradeoff between endangered species and biodiversity conservation: The case of Carabus olympiae (Coleoptera: Carabidae) and carabid diversity in north-western Italian Alps

Abstract

The worldwide loss of biodiversity is of great concern, and this has lead to strong policy frameworks to promote the maintenance of biodiversity through protecting species and habitats in many countries. Often however, rare species with legal protection provide a conservation focus, and therefore may dictate management policy. Co-occurring species, especially those without formal protected status, may contribute significantly to overall biodiversity, but may nonetheless receive limited attention. In such cases, conflicts may arise between the needs of individual species and those of wider biodiversity. We examine such a conflict in alpine ground beetles of the Sessera Valley (NW Italian Alps). This area is the type locality of the endangered species Carabus olympiae Sella, 1855, an endemic species known only from two restricted sites in the Alps. In order to assess priorities for C. olympiae conservation we used habitat suitability modeling, and identified potential indicator species that could serve as an indicator of the occurrence of the target species. In order to assess priorities for ground beetle diversity conservation we described the local ground beetle community by calculating abundance, species richness, average taxonomic distinctness (Δ+), taxonomic distinctness (Δ*) and functional diversity (FD). The best management option for the conservation of ground beetle diversity was found to be maintenance of unforested habitats, in particular pastures, which showed the highest values for all the parameters considered. Forested habitats (artificial plantation and beech forest) had the lowest ground beetle diversity. However, the preferred habitat for C. olympiae was beech forest, especially at medium altitudes (800–1400m) and with sloping terrain. Moreover, C. olympiae presence could be indirectly assessed by the co-occurrence of four indicator species: Tanythrix senilis, Carabus depressuss, Cychrus italicus and Pterostichus appenninus. Our main conclusion is that the most promising landscape-scale approach to preserve both the relict steno-endemic species C. olympiae and the high local syntopic ground beetle diversity is to maintain traditional pastoral activities along with the preservation of the unmanaged beech forests.