Table 5 — Analysis of variance and multiple comparisons for relative height after trampling and after 

 1 year of recovery in Washington's Cascade Mountains 



Source 





After tramplina 







After 1 year 





df 



F 



P 



df 



F 



P 



Number of passes 



3 



19.6 



0.0001 



3 



5.3 



0.002 



Vegetation type 



3 



140.6 



.0001 



3 



2.1 



.10 



Interaction 



8 



.6 



.73 



8 



1.6 



.13 



Significantly different treatments 



Number of passes 25>200,500; 75>500 25>200,500 



Vegetation types^ PH>C,V; PA,C>V none 



^Vegetation types: PH = Phyllodoce, PA = Pachistima, C = Carex, V = Valeriana. 



Calculations of relative vegetation height permit 

 ready comparisons. The immediate response of veg- 

 etation height differed significantly both with the 

 amoiint of trampling and the vegetation type (table 5). 

 The interaction between these two effects was not sta- 

 tistically significant. After the year of recovery, there 

 were no significant differences between vegetation 

 types. The only difference between trampling inten- 

 sities was between the 25-pass lane and the 200- and 

 500-pass lanes. 



In the forb-dominated Valeriana type, relative 

 height was reduced to 29 percent on the 25-pass lane 

 and just 2 percent on the 500-pass lane (fig. 3). In the 

 two shrub-dominated types, Pachistima and Phyllo- 

 doce, only very heavy tramphng reduced height sub- 

 stantially; even on the 500-pass lanes, relative height 

 exceeded 50 percent. The height of the Carex turf was 

 reduced at low trampling levels, but its relative height 

 also exceeded 50 percent on the 500-pass lanes. Dur- 

 ing the year of recovery, however, vegetation on the 



Pachistima myrsinites 



(B) 



Carex nigricans 



O 

 Q. 



20 - 







(C) 

 100 



1 year after trampling 

 After trampling 



100 200 300 400 



Piiyllodoce empetriformis 



500 



700 



200 300 400 



500 



Number of Passes 



Figure 3 — Relative vegetation height after trampling and after 1 year of 

 recovery in four vegetation types in Washington's Cascade Mountains. 

 Vertical bars represent 1 standard error above and below the mean. 



8 



