Roadside diversity in relation to age and surrounding source habitat: evidence for long time lags in valuable green infrastructure Alistair G. Auffret and Evelina Lindgren Data description This dataset contains three csv files, one including the raw species-level data, and two representing the analysed summary information at the site (road verge) and plot scale. SpeciesData.csv - Site = Site (road verge) identifier, 1-36 - Plot = 1m2 plot within each site, 1-10 - Species = Species name (nomenclature: https://www.dyntaxa.se/) - Species_Spec = Is the species a Swedish grassland specialist according to Krauss et al. (2010; https://dx.doi.org/10.1111%2Fj.1461-0248.2010.01457.x)? 0=No, 1=Yes. - Species_Cons = Is the species a Natura2000 grassland species (https://www.naturvardsverket.se/upload/stod-i-miljoarbetet/vagledning/natura-2000/naturtyper/typiskaarter.zip)? 0=No, 1=Yes. - Species_Inv = Is the species invasive to Sweden (https://www.artdatabanken.se/globalassets/ew/subw/artd/2.-var-verksamhet/publikationer/29.-artdatabankens-risklista/rapport_klassifisering_av_frammande_arter2.pdf)? 0=No, 1=Yes. - Site_SNG = Amount of semi-natural grassland in 500 m surrounding the road segment. 1= >15%, 0= <5% - Site_Age = Age of road segment. 1= Historical (present on maps from 1900), 0=Modern (absent from maps from 1900, present on map from 1950s with the exception of Road_3, present on aerial photograph from 1975). - Site_X = X-coordinate of road segment's geographical centroid. SWEREF99TM, EPSG: 3006. - Site_Y = Y-coordinate of road segment's geographical centroid. SWEREF99TM, EPSG: 3006. SiteSummary.csv - Site = Site identifier, 1-36 - Site_SNG = Amount of semi-natural grassland in 500 m surrounding the road segment. 1= >15%, 0= <5% - Site_Age = Age of road segment. 1= Historical (present on maps from 1900), 2=Modern (absent from maps from 1900, present since 1950s). - Site_X = X-coordinate of road segment's geographical centroid. SWEREF99TM, EPSG: 3006. - Site_Y = Y-coordinate of road segment's geographical centroid. SWEREF99TM, EPSG: 3006. - Site_AtlasSquare = Name of 5*5km atlas grid square in which the road segment's centroid resides. - Site_HistOpen = Fraction cover of open land in 500m buffer zone around the road verge from the 1950s, according to Auffret et al. (2017; https://doi.org/10.1111/2041-210X.12788). - Site_pcnm = the first axis of a principal coordinates of neighbour matrix for each site, to control for spatial autocorrelation. - Site_Rich = The number of species recorded in the site. - Site_Spec = The number of grassland specialists recorded in the site. - Site_Cons = The number of grassland conservation species recorded in the site. - Atlas_FracRich = The fraction of the number of species in the plant atlas grid square in which the road segment's centroid resides, that was recorded in the site. - Atlas_FracSpec = The fraction of the grassland specialists in the plant atlas grid square that was recorded in the site. PlotSummary.csv - Site = Site identifier, 1-36 - Plot = 1m2 plot within each site, 1-10 - Site_SNG = Amount of semi-natural grassland in 500 m surrounding the road segment. 1= >15%, 0= <5% - Site_Age = Age of road segment. 1= Historical (present on maps from 1900), 2=Modern (absent from maps from 1900, present since 1950s). - Site_X = X-coordinate of road segment's geographical centroid. SWEREF99TM, EPSG: 3006. - Site_Y = Y-coordinate of road segment's geographical centroid. SWEREF99TM, EPSG: 3006. - Site_pcnm = the first axis of a principal coordinates of neighbour matrix for each site, to control for spatial autocorrelation. - Plot_Rich = The number of species recorded in the site. - Plot_Spec = The number of grassland specialists recorded in the plot. - Plot_Cons = The number of grassland conservation species recorded in the plot.