README for: Dataset for "Traffic intensity and vegetation management affect flower-visiting insects and their response to resources in road verges" Svenja Horstmann Explanation of the information contained in the data file: Dataset_Horstmann_et_al_2024 Rows Each of the 37 rows contains information on one studied road verge habitat. To select road verges, we searched for valuable road verges (‘artrik vägkant’ in Swedish) longer than 200 m and along roads with a speed limit of at least 50 km/h within the environmental and infrastructure data from the national road database (https://nvdb2012.trafikverket.se/). Next, we filtered the selection for road verges surrounded by a maximum of 50 % forest and minimum 30 % arable land within 2 km, and without valuable grassland habitats within 350 m, using data from the National Land Cover Database (Nationella marktäckedata: Naturvårdsverket, 2020) and the TUVA database of meadows and pastures of high nature value (https://etjanst.sjv.se/tuvaut/). We selected 20 valuable road verges at least 2 km apart, along a similar gradient of traffic intensity and half of them mown once and half still twice. We matched each valuable road verge with regular road verge, located between 2 and 20 km away and fitting all traffic and landscape criteria mentioned above. We originally used 10 road verges along a gradient of traffic intensity and in each of the following four categories: Valuable and mowed once, valuable and mowed twice, regular and mowed twice, regular and mowed once. Due to incorrect mowing, we had to exclude three road verges from our analyses and change category for one, resulting in 8 valuable road verges mowed once, 10 valuable road verges mowed twice, 11 regular road verges mowed twice and 8 regular road verges mowed once. Columns SiteID: This is the identifier for each studied road verge. The first number indicates the grouping of sites according to the respective traffic intensity of the adjacent road, and has a value between 0 and 9, with higher values representing higher traffic intensities. N: The latitude of the middle of the 200m long road verge transect in which we inventoried the species data for all studied groups. (WGS 84) E: The longitude of the middle of the 200m long road verge transect in which we inventoried the species data for all studied groups. (WGS 84) RV_Quality: Indicating the road verge quality according to the Swedish Transport Administration (Trafikverket); either ‘valuable’ or ‘regular’. Mowed: The mowing frequency; either 1 or 2. VergeWidthMean: The mean width in meters of the respective road verge, measured from the start of each transect and every 25 m until the end of the transect. TI: The traffic intensity (number of cars per day) of the adjacent roads, derived from the national road database (https://nvdb2012.trafikverket.se/). Flow_Dens: The density of flowering plants in the road verge. We used four non-overlapping segments of each 50 m length within the 200 m long transects in each road verge, covering the whole width of the road verge. Three times between May and July 2021, we assessed every flowering plant within each segment to species or genus level and estimated their abundance in flower units on a scale from 1 to 6 (1: 1-10, 2: 11-50, 3: 51-150, 4: 151-500, 5: 501-1000, 6: > 1001). This was estimated separately for the first 1.5 m of the road verge, and from 1.5 m until the road verge’s far edge. We did this three times in each road verge between May and July 2021. To calculate flower density per transect, we summed the minimum abundance of all species within each flower abundance category (e.g. 1 for category 1: 1-10 flowers, 11 for category 2: 11-50 flowers, etc.) across the whole width and then divided the sum by the mean width of each respective transect. To calculate the flower density per road verge, we summed the flower density of all four respective transects and then used the mean flower density of all three assessment rounds in the analyses. BF_Abun: The sum of the abundance of butterflies and burnet moths (Zygaenidae) during the whole study period. Four times between May and July 2021, we conducted transect walks. Each time, the observer walked for 5 minutes along the 4 50 m transects at a steady pace and caught and identified all individuals within 2.5 m on each side and 5 m in front of them to species level. All transects were located directly alongside the road. For road verges narrower than the planned transect width, the whole road verge was covered. The first three rounds were conducted on the same day as the flowering plant inventory. Butterflies and burnet moths were only surveyed between 10 am and 5 pm, when vegetation was dry, wind was moderate (max. Beaufort 5) and with at least 13 °C if cloud cover was less than 50 %, or at least 17 °C with higher cloud cover. BF_Rich: The mean richness of butterflies and burnet moths (Zygaenidae) of the whole study period (method described above). We only included individuals that we caught and identified to species level (99 % of all butterflies). WB_Abun: The sum of the abundance of all wild bees during the whole study period. Three times between May and July, we conducted transect walks. Four times between May and July 2021, the observer spent 10 minutes walking along each of the 4 50 m long transects of each road verge, catching all individuals within 1.5 m on each side and in front. All three rounds were conducted on the same day as the flowering plant inventory. Wild bees were only surveyed between 10 am and 5 pm, when vegetation was dry, wind was moderate (max. Beaufort 5) and with at least 13 °C if cloud cover was less than 50 %, or at least 17 °C with higher cloud cover. WB_Rich: The mean richness of wild bees of the whole study period (method described above). We only included individuals that we caught and identified to species level (92 % of all wild bees). Vasc_Rich: At each road verge, we surveyed vascular plants in 10 plots of each 1 m2, located across the 200 m long stretch of the road verge, with a fixed distance between all plots. When the narrowest section of the road verge measured less than 2.5 m, we positioned all 10 plots 50 cm from the road surface. In cases where the road verge was wider, we distributed five plots 50 cm from the road and five plots into the centre of the remaining road verge area, alternating between these two positions. We identified vascular plants to species level when possible. We did this once per study site, in July 2021 or 2022. In some occasions, we could only identify the genus but not the species; these were only included in calculating the vascular plant richness of no other species of the same genus occured in the same road verge. BF_Evenness: For the species evenness of butterflies in each road verge, we only included individuals that we caught and identified to species level (99 % of all butterflies). To calculate the Shannon evenness index, we divided the Shannon diversity by the natural logarithm of the species richness. Thus, evenness indicates the relative abundance of species in the community with values between 0 and 1, with higher values representing more even communities. WB_Evenness: For the species evenness of wild bees in each road verge, we only included individuals that we caught and identified to species level (92 % of all butterflies). To calculate the Shannon evenness index, we divided the Shannon diversity by the natural logarithm of the species richness. Thus, evenness indicates the relative abundance of species in the community with values between 0 and 1, with higher values representing more even communities. Columns P-IN: Vascular Plant Species Frequency in each road verge. At each road verge, we surveyed vascular plants presence in 10 plots of each 1 m2. The frequency therefore gives information on the number of plots in which each species occurred per road verge. The plots were located across a 200 m long stretch of the road verge, with a fixed distance between all plots. When the narrowest section of the road verge measured less than 2.5 m, we positioned all 10 plots 50 cm from the road surface. In cases where the road verge was wider, we distributed five plots 50 cm from the road and five plots into the centre of the remaining road verge area, alternating between these two positions. We identified vascular plants to species level when possible. We did this once per study site, in July 2021 or 2022. In some occasions, we could only identify the genus but not the species; in these cases, the individuals are named Genus_sp. Columns IO-JU: Abundance of each species of butterfly and burnet moth observed in our study. In some occassions, we could not catch the individuals and therefore not identify them. These are named "NA_Butterfly", and were used to calculate the overall abundance but not species richness per road verge. Columns JV-MW: Abundance of each species of wild bees observed in our study. In some occassions, we could not catch the individuals and therefore not identify them. These are named "NA_Wildbees", and were used to calculate the overall abundance but not species richness per road verge.