The Valeriana vegetation type lost the most cover 

 when trampled. Relative cover was reduced by more 

 than 50 percent after just 25 passes; 500 passes elimi- 

 nated virtually all the vegetation cover (2 percent rela- 

 tive cover remained). The Phyllodoce type was also 

 quite fragile, although it was significantly more resis- 

 tant than the Valeriana type. Just 25 passes reduced 

 cover significantly. After 500 passes relative cover was 

 only 6 percent. 



The other two types were significantly more resis- 

 tant. In the Carex type, relative cover after 200 passes 

 was not significantly different from the control. On 

 the paths that received 500 and 700 passes, relative 

 cover after trampling was 62 and 43 percent, respec- 

 tively. The Pachistima type lost cover at lower tram- 

 pling intensities than the Carex type, although differ- 

 ences in relative cover were not significant. Relative 

 cover after 75 passes (81 percent) was significantly 

 different from the control; relative cover had declined 

 to 55 percent after 500 passes. 



One year after trampling, disturbance was difficult 

 to detect on all but the most heavily trampled lanes in 

 both the Carex and Valeriana types. Vegetation cover 

 increased substantially, on both of these types, during 

 the year after trampling. The amotmt of recovery was 

 particularly pronounced in the Valeriana type. Rela- 

 tive cover increased from 2 percent shortly after 500 

 passes to 66 percent 1 year later. These two vegeta- 

 tion types, the most different in their initial response 



to trampling, were not significantly different after 

 1 year of recovery. 



The Phyllodoce and Pachistima types had not recov- 

 ered a year after trampling. In each of these types, 

 the 25-pass lane was still significantly different from 

 the control. The relative cover of these two types was 

 not significantly different, but their responses over the 

 year of recovery were very different. Cover on the 

 Phyllodoce type remained relatively unchanged over 

 the year of recovery. Cover increased more than 5 per- 

 cent only on the lane trampled 500 times. In the Pachi- 

 stima type, cover actually declined over the year. Rela- 

 tive cover after 500 passes was 55 percent. During 

 the year after trampling, cover declined to 36 percent. 



Vegetation Height 



Before trampling, ground cover was tallest in the 

 Pachistima type, with a mean vegetation height of 

 25 cm. Ground cover in the Phyllodoce and Valeriana 

 types had mean vegetation heights of 16 and 14 cm, 

 respectively. In the Carex type, mean vegetation 

 height was only 3 cm. Trampling reduced vegetation 

 height in all four types (table 4). Only 25 passes in the 

 Valeriana type reduced the mean height dramatically. 

 In the other three types, mean height was reduced 

 substantially only after high levels of trampling (500 

 passes). Height declined as a result of shortening of 

 stems, flattening of plants, and death of taller plants. 



Table 4 — Mean vegetation height (cm) before and after trampling and after 1 year of recovery for four vegetation types in 

 Washington's Cascade Mountains^ 









Number of passes 











25 



75 



200 



500 



700 



Pachistima myrsinites 















(montane forest) 















Before trampling 



22 (2)1 



23 (3) 



24 (3) 



27 (4) 



28 (2) 





After trampling 



22 (2) 



25 (2) 



20 (5) 



21 (5) 



15(3) 





After 1 year 



28 (2) 



27 (1) 



23 (2) 



26 (3) 



30 (3) 





Carex nigricans 















(alpine turf) 















Before trampling 



3(+) 





3(+) 



3(1) 



3(+) 



3(1) 



After trampling 



3(+) 





3(+) 



3(+) 



2(+) 



2(+) 



After 1 year 



3 (+) 





3(+) 



2(+) 



2(+) 



2(+) 



Phyllodoce empetriformis 















(subalpine heath) 















Before trampling 



17(1) 



15(1) 



16(+) 



16(1) 



17(2) 





After trampling 



17(1) 



15(1) 



15(1) 



16(2) 



12(5) 





After 1 year 



18(1) 



14(1) 



13(1) 



13(1) 



2(1) 





Valeriana sitchensis 















(subalpine forest-meadow) 















Before trampling 



13(2) 



12(1) 



13(2) 



15(1) 



19(5) 





After trampling 



13(2) 



4(1) 



3(+) 



3(1) 



+ (+) 





After 1 year 



13(3) 



10(1) 



9(2) 



8(1) 



8(2) 





^Values in parentheses are 1 standard error. A + indicates mean height or standard error less than 0.5 cm. 



7 



