the case of Valeriana. The greater the diversity, the 

 more hkely it is that species will differ in durability. 

 The physiognomic diversity of the Phyllodoce type, pri- 

 marily shrubs and forbs, resulted in a longer-term shift 

 in species composition than for the Valeriana type, 

 which had a diversity of forbs, but almost no shrubs. 



General Appearance 



A final indication of response is the visual evidence 

 of change after trampling. This was evaluated by de- 

 scribing the appearance of the lanes after each level 

 of trampling. Particular attention was given to the 

 amount of trampling that produced an easily discern- 

 ible path, as evidence of previous use often encourages 

 additional use of the path. Concentration of use can 

 lead to accelerated impact. 



Obvious changes occurred most rapidly in the Valer- 

 iana type, which was dominated by forbs. After 75 

 passes, most upright stems had been knocked down 

 and an obvious path was created; most vegetation 

 had been eliminated and all vegetation was flattened 

 after 200 passes; virtually all vegetation was gone af- 

 ter 500 passes. An obvious path developed after 75 

 passes in the Phyllodoce type, which was dominated 

 by dwarf shrubs. However, substantial vegetation sur- 

 vived 200 passes. After 500 passes, many upright stems 

 remained, but they were clearly damaged. A path be- 

 came evident only after 200 passes in the shrubby 

 Pachistima type. On the 500-pass lanes, the vegeta- 

 tion appeared ragged because stems and leaves had 

 been damaged, but many of the shrubs survived. In 

 the Carex type, a path was not obvious before 500 

 passes. Even on the 700-pass lanes, a continuous turf 



remained, although about half of the sedges appeared 

 to have been killed. 



One year after trampling, paths were evident only 

 in the Pachistima and Phyllodoce types, both domi- 

 nated by shrubs. In the Pachistima type, dead shrubs 

 and shrubs with few leaves were evident on the 200- 

 pass lanes, but a path was evident only on the 500- 

 pass lanes. In the Phyllodoce type, dead shrubs and 

 leafless stems were evident even on the 75-pass lanes, 

 and a brown path was evident on the 200-pass lanes. 

 In the other two types, a careful observer could see 

 that vegetation was shorter and that cover had been 

 reduced, but only on the most heavily trampled lanes. 

 A casual observer probably would not have detected 

 any evidence of disturbance. 



Summary Indicators 



Five indicators of vegetation response, both imme- 

 diately after trampling and after 1 year of recovery, 

 are listed in table 6. The Carex turf, dominated by 

 graminoids, was most resistant to all types of change 

 other than reduction in height. Even on the most 

 heavily trampled lanes, changes in this type were 

 minor; recovery was virtually complete after 1 year. 

 The Valeriana type, dominated by lush forbs, was the 

 least resistant to all types of change. Even relatively 

 low levels of trampling substantially reduced cover, 

 reduced vegetation height, eliminated many species, 

 shifted species composition, and created an obvious 

 trail. The Valeriana type was highly resilient, how- 

 ever. After 1 year of recovery, the only evidence of 

 trampling was a moderate reduction in height and 

 cover on the most heavily trampled lanes. 



Table 6 — Summary indicators of resistance and tolerance for four vegetation types in Washington's Cascade Mountains 



Vegetation type 



Pachistima Carex Ptiyllodoce Valeriana 



Resistance indicators^ 



Relative cover (percent) 71 85 39 16 



Relative height (percent) 75 71 89 18 



Species richness (number of passes) 200 500 200 25 



Species composition (number of passes) >500 >700 200 75 



Evident path (number of passes) 200 500 75 75 



Tolerance Indicators^ 



Relative cover (percent) 58 97 41 80 



Relative height (percent) 83 85 59 65 



Species richness (number of passes) >500 >700 >500 >500 



Species composition (number of passes) >500 >700 200 >500 



Evident path (number of passes) 500 >700 200 >500 



^Resistance Indicators refer to immediate responses to trampling. They include mean relative cover and relative height, after tram- 

 pling, for to 500 passes, as well as the minimum number of passes that causes a significant reduction in species richness or floristic 

 similarity, or that results in an evident path. The relative cover and relative height values are the durability indices described in the data 

 analysis section. 



^Tolerance indicators refer to conditions 1 year after trampling. 



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