Roads support the spread of invasive Asclepias syriaca in Austria

Abstract

Summary Asclepias syriaca is an invasive alien plant that has recently spread in Central Europe. The spatiotemporal spread of A. syriaca was reconstructed based on the distribution data for Austria. A. syriaca has increased in abundance and range, especially after the year 2005. At present, the species occurs primarily in eastern Austria (Vienna, Lower Austria), while it was rarely recorded in southern and western Austria. Further spread and range filling is probable. Moreover, the distribution of A. syriaca along roadsides and the role of road type and adjoining land use in facilitating its spread were studied in an area of high presence of the species in Lower Austria in 2018. It was shown that A. syriaca occurred regularly along roadsides and the chance of finding A. syriaca was higher along unpaved roads and along roadsides bordered by forests and grassland. The results indicate that the road network contributes to the spread of A. syriaca in the study area, most likely by providing suitable and well connected habitats. If A. syriaca densities are to be lowered, emphasis should be placed on both a proper roadside management (e.g., mowing regimes) and on the control of the species in the respective adjacent habitat.