FIELD TECHNIQUES 



At each plot, 17 treatment lanes, each 1 ft (0.3 m) wide 

 and about 16 ft (5 m) long, were delineated. Each set of 

 two treatment lanes was separated by a 1.6- by 16-ft 

 (0.5- by 5-m) buffer strip to permit sampling without dis- 

 turbance of the treatment lanes. Where the land sloped, 

 the lanes were oriented parallel to the contours. 



One of the treatment lanes was a control; it was never 

 trampled. The other treatments consisted of four sets of 

 four lanes trampled at the following frequencies through- 

 out the 8-week season: once (IX). three times (3X), eight 

 times (once per week— 8X), and 16 times (twice per 

 week— 16X). The numbers of passes administered each 

 time to the IX and 3X lanes were 5, 25, 100, and 300. 

 The 8X and 16X lanes received 5, 25, 75, and 100 passes 

 each time (fig. 9). One pass is a one-way walk along the 

 lane. The total number of passes per season is trampling 

 frequency (1, 3, 8, or 16) times the number of passes. 

 For example, total passes on the four 8X lanes were 40 

 (8X5), 200 (8X25), 600 (8X75), and 800 (8X100). In each 



plot, then, one lane received 0, 5, 15, 25, 40, 75, 80, 100, 

 200, 400, 600, 800, 900, 1,200, and 1,600 total passes per 

 season and two lanes received 300 passes— one in a sin- 

 gle treatment and one in three treatments of 100 passes. 

 The treatment assigned to each lane was randomized. 

 All treatments were replicated in a second plot in each 

 habitat type with the exception of the ABLA/CLUN and 

 ABLA/CLUN-VACA types. 



Initial measurements were taken on each lane in mid- 

 June 1981. Measurements were taken in four 0.66- by 

 1.64-ft (2- by 5-dm) subplots, systematically placed— in 

 the center of each lane— 3.3, 6.5, 9.8, and 13.1 ft (1, 2, 3, 

 and 4 m) from one end of the lanes. In each subplot the 

 cover of total vegetation, exposed mineral soil, each vas- 

 cular plant species, and mosses and lichens, each as a 

 group, was estimated to the nearest percent if under 10 

 percent or in 10-percent coverage classes between 10 and 

 100 percent. 



Trampling commenced the last week of June and con- 

 tinued for 8 weeks until late August. The IX treatment 

 occurred in late July. The 3X treatments occurred at 



9.1 M 



"7^ 



5 M 



BUFFER STRIPS, 0.5 M WIDE 

 — TREATMENT LANES, 0.3 M WIDE 



16 TREATMENTS, PLUS A CONTROL, WERE RANDOMLY ASSIGNED TO LANES 



ONCE/8 WEEKS (IX) 



5 PASSES 

 25 

 100 

 300 



THREE TIMES/8 WEEKS (3X) 



5 PASSES 

 25 

 100 

 300 



ONCE/WEEK (8X) 



5 PASSES 

 25 

 75 

 100 



TWICE/WEEK (16X) 



5 PASSES 

 25 

 75 

 100 



Figure 9.— Layout of the experimental plot and treatments. 



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