(A) Trifolium parryi 



■| QQ After trampling 



C 



o 

 o 



a> 



Q. 



E 



.2 1 

 o 



80- 



60 — 



40 — 



20 — 



X 



X 



00 



25 75 200 500 



(C) Vaccinium scoparium 



After trampling 



U. 80- 



60— 



40- 



20 - 



25 75 200 500 



After 1 year 



X 



25 75 200 500 



After 1 year 



(B) Kobresia myosuroides 



After trampling 



75 200 500 700 



(D) Geranium richardsonii 



After trampling 



25 75 200 500 25 75 200 500 



Number of Passes 



Figure 14 — Floristic similarity, comparing composition before and after disturbance, in four 

 vegetation types in Colorado's Rocky Mountains. Vertical bars represent 1 standard error 

 above the mean. 



After 1 year 

 I 



75 200 500 700 



After 1 year 



25 75 200 500 



Summary Indicators 



The Trifolium type, dominated by matted and creep- 

 ing forbs, along with short, tufted graminoids, was 

 most able to tolerate trampUng. It resisted all five of 

 the changes examined (table 12). Even the 500-pass 

 lanes returned to the original conditions within 1 year. 

 The Kobresia type was even more resistant to cover 

 loss, but it lost more species and was flattened more 

 than Trifolium. More important, it was less resilient 

 than Trifolium. On the more heavily trampled lanes, 



cover, height, and richness remained depressed 1 year 

 after trampling. 



The other extreme, in terms of initial response, was 

 the Geranium type, dominated by erect forbs. Even 

 relatively low levels of trampling reduced cover sub- 

 stantially, reduced vegetation height, eliminated many 

 species, shifted species composition, and created an 

 obvious trail. One year after trampling, recovery in 

 this type was second only to Trifolium. 



The response of the Vaccinium type, dominated by 

 dwarf shrubs, was unique. It experienced moderate 



22 



