Hiking trails extending from high elevations aid further spread of alien plant species in subalpine and alpine zones

Hiking trails, as anthropogenic linear habitats in highly protected mountain areas, allow the spread of alien plant species. Here, we focused on hiking trails extending away from high-elevation ropeway termini in Japan and assessed whether alien plant species that invaded the termini (i.e., trail heads) have spread along the trails. We recorded alien plant species along hiking trails leading from ropeway termini on seven mountains and analyzed the plant characteristics that influence their occurrence. The number of alien plant species along the trails and the number of records of their occurrence were positively affected by the number of species around the trail heads, and were negatively affected by the elevation of the trail head. A species-level analysis indicated that the number of records of each species’ occurrence on trails was higher with the presence of each species around the trail head, with perennial life-span, and with a smaller seed mass. Our results show that hiking trails leading away from high-elevation ropeway termini can spread alien plant species up to a distance of ca. 700 m into alpine communities. This study provides evidence of the role of hiking trails in the spread of alien plant species into subalpine and alpine zones.