The conservation value of Aculeata communities in sand quarries changes during ecological succession

Sand quarries that are used occasionally and not subjected to rehabilitation are important biodiversity banks in both anthropogenic and semi-natural landscapes. However, their value for biodiversity preservation can change due to dynamic successional processes. We determined the responses of three Aculeata guilds: herbivores (Apiformes), predators (Crabronidae, Sphecidae), and parasitic species (Apiformes, Chrysididae, Crabronidae) to successional transformations in 32 sand quarries, along a successional chronosequence covering 15 years of spontaneous regenera-tion, classified into three stages (early, middle and late succession). Responses to succession differed depending on the trophic guild of the Aculeata. Values of community characteristics for herbivores and parasitic species were the highest in the middle stages of succession, whereas for predators, they did not change. The arrival of new species significantly affected the community structure of all three Aculeata guilds, although dominance structure did not change. However, only for predators, turnover was higher in the later successional stages. This was manifested by a rapid accumulation of new and rare species. In contrast, for parasitic species the species turnover decreased, and in the case of herbivores, it remained constant throughout the successional stages. Predators were also characterized by the highest number of species, present at all successional stages. We emphasize that the various patterns of species turnover can influence the conservation value of sand quarries assessed as numbers of rare and/or threatened species as well as other community characteristics and structure. The collected information will allow a more deliberate selection of protective measures to facilitate the preservation of these valuable habitats.