The role of wild bees and cavity-nesting wasps as ecological indicators of the last traditionally managed meadows in Eastern Europe

The number of wild bees and cavity-nesting wasps is abundant in agricultural areas and they contribute significantly to ecosystem services. Due to their specialization in nesting sites and  food sources, these groups are sensitive to habitat condition changes and they are therefore important indicators for environmental impact assessments. As semi-natural habitats are steadily declining and often understudied, their significance for research is increasingly recognized. During this research, the role of wild bee species and cavity-nesting Hymenopteran taxa as indicators was examined, along the unique combination of high nature value and traditional land use habitats in Central Europe, Transylvania. Transects and trap nests were used to test the diversity and abundance of wild bees and cavity-nesting Hymenopterans in order to identify possible differences between highly protected and less protected areas. The differences in taxonomic groups between the sites and the potential effects of l..., Study sites
Our research was carried out in Transylvania (Romania) between 2018 and 2019 in areas with traditional cultivation, extensive farming and high nature value. These areas rich in trees and shrubs have a high plant diversity and density. All study areas were located on the border of the counties of Hargita and Kovászna in a hilly-mountainous landscape, where the average altitude is 580m. These areas are mainly used as mowing fields. Mosaic plots rarely exceed one hectare in size and are relatively far from villages. The mosaic plots are mowed at different times of the year, providing a continuous source of food for pollinators throughout the year. The majority of the study sites was located in the Vargyas valley, which is part of the Natura 2000 network. The importance of these high nature value areas has recently increased due to the intensification of agriculture. There were three study areas, which were located within or in close proximity to Natura 2000 sites (Figures 1a an..., , # The role of wild bees and cavity-nesting wasps as ecological indicators of the last traditionally managed meadows in Eastern Europe

[https://doi.org/10.5061/dryad.dr7sqvb76](https://doi.org/10.5061/dryad.dr7sqvb76)

## The dataset consists of the six following .csv-files:

1.    “Species_list_wild_bees”: List of the wild bee species (species and individual numbers) sampled at the study sites during the two study years. The ID-codes of study sites are combinations of capital letters and numbers (e.g. K1, K2, etc.).

2.    “Trap_nests”: List of the nests of different cavity-nesting Hymenopteran taxa (species and individual numbers) found at the study sites during the two study years. The column “Code” consists of the ID-codes of the trap nests, while the column “Reed” lists the ID-numbers of the (occupied) reed stalks (with Hymenopteran nests). The column “Diameter” provides the diameter of the occupied reed stalks in mm. The column “Cells” is the sum of empty and occupied (brood) cel...