Data for manuscript: Landscape-level oilseed rape cover shapes seasonal patterns of wild bee abundance in conservation areas

Flowering oilseed rape (OSR) is known to attract pollinators, however, knowledge about its effects on pollinator populations in adjacent semi-natural habitats over the season remains vague. We therefore asked how OSR cover affects bee abundance in high-value semi-natural habitats throughout the season, and how habitat area, quality, and bee life-history traits modulate these effects. To answer this, we sampled bees in 40 semi-natural calcareous grasslands in Germany. Bees (Hymenoptera: Apiformes) were sampled using sweep-netting in two sampling rounds during OSR flowering (May) and after OSR flowering (June) in 2022. We used variable transect walks with no fixed direction to sample bees. Transect length was 750 m and transect width was 2 m resulting in 1500 m² transect area regardless of sampling site area. Transect time was 45 minutes. Wild bee species were classified as endangered or not endangered according to the Red List of Bavaria and were categorized in different traits. To estimate the effects of OSR cover in the surrounding landscape on bee abundance in calcareous grasslands, we calculated the percentage OSR cover within a 2 km radius of the calcareous grasslands. Additional local and landscape variables which are expected to affect bee abundance were used as control variables in the analyses. The effects of landscape OSR cover on bee abundance during and after OSR flowering were estimated using generalized linear models (GLM). The data sets include the name and coordinates of the sampling sites, the response variable bee abundance (distinguishing between the timing of OSR flowering and bee traits) and the predictor variables OSR cover (2022/2021), habitat area, mean field size, nesting sites, flower cover, flower richness and annual mean temperature. The attached R code (.rmd) allows the results of the study to be reproduced.