Hiker, horse and llama trampling effects on native vegetation in Montana, USA

Intensity of trampling disturbance varies with type of recreation traffic. The purpose of this study was to assess the relative impact of hiker, horse and llama traffic on vegetation and groundcover conditions. Hiker, horse and llama traffic were applied at two trampling intensities (25 and 150 passes at one time) to two previously undisturbed forested vegetation types (one with an understory dominated by erect forbs, the other dominated by low shrubs). Trampling effects were assessed immediately after traffic application and 1 year later. For most impact parameters, intensity of trampling impact varied with type of user. For all parameters that varied with type of user: (1) horse traffic caused the most disturbance; and (2) hiker and llama impacts could not be differentiated statistically. The forb-dominated vegetation type was highly vulnerable to vegetation impact but recovered rapidly. The shrub-dominated type was more resistant but lacked resilience. Higher trampling intensities caused more disturbance but the relationship between trampling intensity and disturbance intensity was non-linear.1998 Academic Press