Impacts of experimental trampling by hikers and pack animals on a high-altitude alpine sedge meadow in the Andes

Abstract

Background: Damage to alpine plant communities is likely to occur when hikers and pack animals trample vegetation. Currently, there is limited research that quantifies and compares impacts from these activities. Aims: A manipulative experimental protocol was used to assess damage to alpine meadows by pack animals and hikers in the Aconcagua Provincial Park, Andes, Argentina. Methods: Vegetation height, overall cover, cover of dominant species and species richness were measured immediately after, and 2 weeks after different numbers of passes (0, 25, 100 and 300) by hikers or pack animals in an experiment, using a randomised block design. Results: Pack animals had two to three times the impact of hiking on the meadows, with greater reductions in plant height, the cover of one of the dominant sedges and declines in overall vegetation cover after 300 passes. Impacts of pack animals were also apparent at lower levels of use than for hikers. These differences occurred despite the meadow community having relatively high resistance to trampling due to the traits of one of the dominant sedges (Carex gayana). Conclusions: Pack animals caused more damage than hikers to the alpine meadow, but the scale of the difference in short-term impacts depends on the characteristics of the plant community, the amount of use and the vegetation parameters measured. Use of the meadows by hikers and pack animals should be minimised as these meadows are scarce, and have high conservation values.