No abstract

No abstract

Changes in bee fauna, such as the disappearance of certain species or increasing abundance of others, are very important. The common belief that pollinating insects are facing problems also prompts detailed studies of the bee fauna in order to track on-going changes. Assessment of the state of bee communities in particular ecosystems or ecosystem complexes within a landscape, tracing the course of trends in fauna and also predicting their future structures resulting from current changes, are only possible if sampling is carried out at an appropriate frequency, so that representative materials are obtained. The aim of the present study was to determine what sampling intensity during the growing season would enable the collection of representative materials to evaluate species diversity of bees in a study area. Repeated bee sampling at monthly intervals throughout the period of activity of bees resulted in the identification of 73 bee species, corresponding to 51.4 % of the estimated number of bee species in the study area. When samples were obtained twice a month, 93 bee species were captured, accounting for 65.5 % of the estimated number of bee species. When sampling took place nearly four times a month, 108 bee species were captured, making up 76 % of the estimated number of bee species; the materials obtained at this sampling rate may be regarded as representative. The importance of accounting for the phenology of a given animal group during a sampling effort is also emphasised.

Research on wild bees (Apiformes) was conducted in the Lower Oder Valley (NW Poland) at Natura 2000 sites near the border between Poland and Germany. The analysis involved 3 landscape types with xerothermic and sandy grasslands, differing in the proportion of woody vegetation. In total, we collected there 4158 specimens of Apiformes, representing 180 species. We have proved that mid-forest grasslands with a high proportion of thermophilous broad-leaved forests and xerothermic shrub communities are equally attractive to wild bees as open habitats (sandy grasslands, xerothermic grasslands/heaths). We observed varied responses of wild bee species with specific functional characteristics to increasing proportion of woody vegetation. The grasslands surrounded by forests were characterized by the highest number of cleptoparasitic species. In contrast, solitary and social bee species preferred forest-steppe habitats. However, in open habitats, solitary bees were the most abundant. Moreover, open habitats were distinguished by the highest number and abundance of rare species. Active protection of thermophilous grasslands is crucial for biodiversity conservation, also with respect to the natural resources of Apiformes. Preservation of biodiversity in threatened xerothermic and sandy grasslands should be one of the key objectives of nature conservation in European countries. Currently, more and more actions are undertaken to improve their condition and to restore those particularly valuable and threatened habitat types.

No abstract