Experimental trampling of vegetation. I. Relationship between trampling intensity and vegetation response.
Experimental trampling, to simulate recreational use, was conducted in 18 vegetation types (including coniferous and deciduous forests. dwarf scrub, meadows and grasslands) in five separate mountain regions in the United States. Each type was trampled 0-500 times. Response to trampling was assessed by determining vegetation cover 2 weeks after trampling and 1 year after trampling. Response varied significantly with trampling intensity and vegetational type. Trampling intensity and vegetational type explained more of the variation in vegetation cover 2 weeks after trampling that they did 1 year after trampling. For most vegetation types, the relationship between vegetation cover after trampling and trampling intensity was best approximated by a second order polynomial of the form Y = A - BX + CX2. The relationship was linear in a few vegetation types. The curvilinearity of the relationship between trampling intensity and surviving vegetation cover decreased with increases in resistance, tolerance and species diversity of the vegetation type.