Visitors off the trail: Impacts on the dominant plant, bryophyte and lichen species in alpine heath vegetation in sub-arctic Sweden

Abstract Alpine ecosystems are under increasing pressure due to tourism and recreational activities. When leaving designated trails as is frequently observed, visitors can cause unintentional damage to vegetation. This study investigated the effect of human trampling on the dominant species of vascular plants, bryophytes and lichens along an infrequently used hiking trail in an alpine ecosystem in sub-arctic Sweden. The hypothesis tested was that proximity to the trail (as an effect of more people leaving the trail for a short distance compared to a longer distance) causes a decrease in species with low resistance to trampling. With a greater decrease in taller forbs and shrubs than in graminoids and prostrate plants, a greater decrease in lichen than in bryophyte species, and a change in vegetation composition. The results showed that proximity to the trail did not cause a decrease in the majority of dominant species, with none of the eight most dominant vascular plants showing any significant effects of proximity to the trail. One bryophyte species (Dicranum elongatum) among the six most commonly found decreased with proximity to the trail. Three lichen species (Cladonia arbuscula, Cladonia uncinalis, Ochrolechia frigida) among the eight most common species decreased with proximity to the trail. There was no evidence that taller species decreased with proximity to the trail, although the deciduous shrub Betula nana showed a tendency for a decrease. Proximity to the trail caused a greater decrease in lichen species than in bryophyte species. Multivariate analyses showed that distance from trail and transect direction had significant effects on overall vegetation composition. The level of low-intensity trampling recorded indicates that current numbers of hikers at the site can be sustained for longer periods with minimum impact on vascular plant species, but to get a more general understanding of the impact of low-intensity trampling data from additional sites are needed.