Data from: Conservation of pollinators in traditional agricultural landscapes – new challenges in Transylvania (Romania) posed by EU accession and recommendations for future research

Farmland biodiversity is strongly declining in most of Western Europe, but still survives in traditional low intensity agricultural landscapes in Central and Eastern Europe. Accession to the EU however intensifies agriculture, which leads to the vanishing of traditional farming. Our aim was to describe the pollinator assemblages of the last remnants of these landscapes, thus set the baseline of sustainable farming for pollination, and to highlight potential measures of conservation. In these traditional farmlands in the Transylvanian Basin, Romania (EU accession in 2007), we studied the major pollinator groups—wild bees, hoverflies and butterflies. Landscape scale effects of semi-natural habitats, land cover diversity, the effects of heterogeneity and woody vegetation cover and on-site flower resources were tested on pollinator communities in traditionally managed arable fields and grasslands. Our results showed: (i) semi-natural habitats at the landscape scale have a positive effect on most pollinators, especially in the case of low heterogeneity of the direct vicinity of the studied sites; (ii) both arable fields and grasslands hold abundant flower resources, thus both land use types are important in sustaining pollinator communities; (iii) thus, pollinator conservation can rely even on arable fields under traditional management regime. This has an indirect message that the tiny flower margins around large intensive fields in west Europe can be insufficient conservation measures to restore pollinator communities at the landscape scale, as this is still far the baseline of necessary flower resources. This hypothesis needs further study, which includes more traditional landscapes providing baseline, and exploration of other factors behind the lower than baseline level biodiversity values of fields under agri-environmental schemes (AES). Sampling data of wild bees and hoverflies in TransylvaniaMetadata of the dataset used by the following paper accepted in Plos One in March 2016 (Ref. No: PONE-D-15-36138R1). These pollinator data were sampled by transect walk method in Transylvanian arable fields and grasslands in 2012, in a case study financed by the "Lendület" program of the Hungarian Academy of Sciences. Guideline for abbreviations used in the name of variables is provided in the file.PONE-D-15-36138_datarepository.xlsxSpecies list of wild beesSpecies list of wild bees with their abundance (number of individuals) in arable fields and grasslands, lecty category and conservation interest in the studied arable fields and grasslands in Transylvania, Romania. IUCN European Red bee list categories are presented at geographical Europe scale (EN – Endangered; VU – Vulnerable; NT – Near Threatened; LC – Least Concern; DD – Data Deficient).PONE-D-15-36138R1_S2_Table.docxSpecies list of hoverfliesSpecies list of hoverflies with their abundance (number of individuals) in the studied arable fields and semi-natural grasslands in Transylvania, Romania.PONE-D-15-36138R1_S3_Table.docxGoogle Earth map of the studied arable fields and grasslandsSites were assigned in the vicinity of 19 villages in the Transylvanian Basin, Romania. Sites are named by the first three letters of the closest village, A (arable) or P (grassland) indicates the land use type, plus H (heterogeneity) and W (woody vegetation cover) values in a 3 value range. Heterogeneity was defined as the standard deviation of the 2.5m panchromatic Spot picture, stratified in quantiles: H1 – belonging to lower third (low heterogeneity), H2 – middle third, H3 – upper third. Woody vegetation cover represented the proportion of woody vegetation (shrubs and trees) in a 1 ha circle based on classified 10m SPOT 5 data: W1: 0 to 5 % woody vegetation cover; W2: 5 to 15 % of woody vegetation; W3: 15 to 50 % of woody vegetation (1 – low, 2 – middle, 3 – high).PONE-D-15-36138R1_S1_Figure.kml