Road slopes in temperate Andean-Patagonian forests: an opportunity for alien plant invasion?

Abstract

Roads create favorable habitats for the introduction and dispersal of alien plants, favoring biological invasions. Environmental conditions affect the pattern of invasion, altering their distribution along the different type of forests. The aim was to evaluate the impact of roads on plant community composition and invasive alien spread across different Andean-Patagonian forest types: Austrocedrus chilensis (ciprés), Nothofagus dombeyi (coihue), and Nothofagus pumilio (lenga). We compared species richness, diversity, cover, and the degree of invasion by alien species between road cut slopes (RS) and adjacent reference areas (RA) within each forest type, as well as among road cut slopes across the different forest types. We found that the richness, diversity, and cover of invasive species and the degree of invasion in the RS decreased with the type of forests. In ciprés and coihue forests, the richness and diversity of invasive species in the RS were higher than in the RA, but not in lenga. In the RS of the three forests, native species cover was lower than in the RA. The composition of alien and native species was different in both habitat types. We conclude that road slopes present an opportunity for the invasion of alien plants into natural areas of Patagonian forests. The presence, diversity, and richness of invasive alien species vary among the road slopes depending on the forest type, in accordance with the elevational gradient. Early detection of the invasion is relevant to devise control and management actions in response to climate change.