Exotic plant species : A study of road verges

In Sweden, there are about 2,000 alien species of which 388 are invasive alien species. Invasive alien species are species that compete and create problems for the native species we have in our nature. One of the major drivers of the introduction of alien species is transport. Transport between different geographical areas increases from year to year, making it easier for new alien species to enter the country. The purpose of this work is to investigate the distribution of alien species along roads of different sizes with different amount of traffic, to be able to get an overview of how the number of cars passing a road affects the spread of alien species and whether it differs among roads. Roads of different sizes were inventoried, in the municipalities of Lekeberg and Laxå, Sweden. Two of the roads were highways, 3 middle sized roads and 3 small sized roads. All species in the sample sites were inventoried, including native species. One-way Anova was used to check if there were any significant differences. The result shows that where most alien species were found, least native species could also be found. Other studies have found linkages between paved roads and invasive species, where it was found that paved roads had more alien species than gravel roads. The result of this study showed that most foreign species could be found along the middle roads and least along the small roads. This could be due to the smaller roads having less traffic intensity, which means that there is less chance of alien species entering these roads by cars. The fact that most species were found on the intermediately sized roads compared to the highways may be due to the higher speed and a higher traffic flow.