CONICET | Buscador de Institutos y Recursos Humanos

The introduction of alien species represents one of the greatest threats to biodiversity worldwide.Highway construction increases the dispersal and invasion of exotic plant species.This study examined the assembly process of the plant communities to determine whetherthe roadsides of the Patagonian steppe represent a reservoir and dispersal source of invasiveexotic species. We analyzed the composition of exotic and native species and functionalgroups present in the established vegetation and seed banks of roadsides andreference areas nearby. The type of dispersal of exotic and native species at the roadsideswas also evaluated. Total cover and that of exotic and native species was lower at the roadsidesthan in the reference areas; however, at the roadsides the cover and seed abundanceof exotic species was higher than that of native species. In the roadsides vegetation, nativeshrubs such as Acaena splendens predominated, along with exotic perennial herbs andgrasses which were mainly represented by Rumex acetosella. In the seed bank the predominantspecies were exotic perennial herbs, also represented by R. acetosella, annual exoticspecies such as Epilobium brachycarpum and Verbascum thapsus, and annual native speciessuch as Heliotropium paronychioides. No exotic shrubs were found either at the roadsidesor in the reference areas. The species at the roadsides did not present a dominanttype of dispersal. The abundance of exotic species at the roadsides, both in the abovegroundvegetation and the seed bank, may be due to the stressful environment and thecharacteristics of the species themselves, such as the ability to form seed banks. This workrevealed that the roadsides of the Patagonian steppe constitute reservoirs of invasive exoticspecies, highlighting the importance of identifying them and controlling their spread, with aview to generating ecosystem management programs.

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