Neophyte invasions in European grasslands
Creators: name: Axmanová, Irena
name: Kalusová, Veronika
name: Danihelka, Jiří
name: Dengler, Jürgen
name: Pergl, Jan
name: Pyšek, Petr
name: Večeřa, Martin
name: Attorre, Fabio
name: Biurrun, Idoia
name: Boch, Steffen
name: Conradi, Timo
name: Gavilán, Rosario G.
name: Jiménez-Alfaro, Borja
name: Knollová, Ilona
name: Kuzemko, Anna
name: Lenoir, Jonathan
name: Leostrin, Artem
name: Medvecká, Jana
name: Moeslund, Jesper Erenskjold
name: Obratov-Petkovic, Dragica
name: Svenning, Jens-Christian
name: Tsiripidis, Ioannis
name: Vassilev, Kiril
name: Chytrý, Milan
Publisher: name: Zenodo
Year: 2021
Subjects: alien
continental scale
EUNIS habitat
Europe
European Vegetation Archive (EVA)
grassland
invasion level
invasion success
neophyte
plant invasion
semi-natural vegetation

description: <strong>Maps of neophyte invasions in European grasslands. </strong> Supporting materials to the study: Axmanová, I., <em>et al.</em> (2021) Neophyte invasions in European grasslands. <em>Journal of Vegetation Science</em> 32. The human-related spread of alien plants has serious environmental and socioeconomic impacts; therefore, it is important to know which habitats are most threatened by invasion and why. In this study, we focused on European grasslands, and one of our aims was to assess how invasion levels differ across European regions. We selected 97,411 grassland vegetation plots from the European Vegetation Archive (EVA) and assigned a native or alien status to each of the 8,212 vascular plant species found in these plots. We considered only neophytes (alien species introduced after 1500 AD), which we further divided according to their geographical origin. To track geographical patterns at the level of invasions, we used UTM grid cells of 50 km × 50 km. We mapped only grid cells containing more than 10 plots in order to avoid the interpretation of random patterns. For each grid cell, we calculated: i, Percentage proportion of invaded plots, i.e. what percentage of plots within a given grid cell have at least one neophyte present. We also prepared separate maps for grassland habitat groups and different origin categories of neophytes (maps 001-024). Oromediterranean habitat group had no invaded plots, thus it was not mapped. For comparison, we also prepared a map in which the minimum limit for mapping a grid cell (ten plots) was not applied and all grid cells were mapped (map 025). ii, Mean absolute neophyte richness (number of neophytes in a plot). The values shown in the map were calculated as the mean of all plots recorded in a given grid cell (map 026). iii, Mean relative neophyte richness (number of neophytes in a plot relative to all species in the plot). The values shown in the map were calculated as the mean value across all plots recorded in a given grid cell (map 027). iv, Mean absolute neophyte cover (percentage cover of neophytes). The values shown in the map were calculated as the mean value across all plots recorded in a given grid cell (map 028). v, Mean relative neophyte cover (percentage cover of neophytes relative to the total cover of all species in a plot). The values shown in the map were calculated as the mean across all plots recorded in a given grid cell (map 029). Colour-scale categories were defined using the <em>k</em>-means algorithm, reflecting the distribution of the variables. Grey colour indicates cells with only non-invaded plots. Maps were prepared using the R packages ‘raster’ (Hijmans <em>et al</em>., 2020), ‘rgdal’ (Bivand <em>et al.</em>, 2020), ‘spatialEco’ (Evans <em>et al.</em>, 2020) and ‘berryFunctions’ (Boessenkool, 2020). <br> Cite as: Axmanová, I. <em>et al</em>. (2021) Neophyte invasions in European grasslands. <em>Journal of Vegetation Science</em> 32.