The hillside pits, 3 by 3 feet and about 6 inches deep in the center, were prepared 

 shortly before the seedlings were planted in early June 1964. The glass fiber mats and 

 polyethylene sheets were held in place by three, or more, 1-foot-long wire pins. Sima- 

 zine pellets were scattered evenly at a rate of 5.67 grams per pit; the cost of herbi- 

 cide per seedling was 3.2 cents. As a followup, live seedling tallies were made each 

 fall through 1968. 



Rainfall at the Zena Creek study area, June to September 1964, was 175 percent of 

 normal (table 4). This exceptionally wet summer undoubtedly had a bearing on seed- 

 ling survival patterns. 



First-year survival was the highest of any comparable plantings at Zena Creek. 

 Aspect differences were significant but treatment differences were not. Survival was 

 greatest on the west aspect (Appendix II). Probably the generous recharging of soil 

 moisture during the summer was a big factor in the relatively high survival when using 

 black polyethylene mulch. This lateral recharging, coupled with the relatively cool 

 summer of 1964, probably reduced the high temperature-moisture deficit impact of the 

 black polyethylene, giving a slightly greater survival level than was found in the 

 1963 tests. 



Black polyethylene improved survival on both aspects (fig. 6) , but was the best 

 treatment on the east aspect. Simazine also improved survival on both aspects; it was 

 best on the west, more moist aspect. By 1968 all treatments on the east aspect ap- 

 peared to be much more effective than those on the west aspect when measured against 

 the no-mulch treatment. In 1968, however, treatments differed significantly (p = 0.01), 

 as reflected by the following tabulation: 



Tveatment East West 



(Fevoent of survival) 



Control (no mulch) 28 61 



Glass fiber mulch 42 60 



Polyethylene mulch 55 66 



Simazine 44 70 



The range in treatment effects increases with time for both aspects, i.e., dif- 

 ferences became more prominent with time (fig. 6). This fact underscores the cumulative 

 effect of less advantageous conditions. The large increase in the range between 1965 

 and 1966 may be attributed to a dearth of rainfall between June and September (table 4). 

 Total precipitation in these months was only 33 percent of normal. 



Seedling heights were recorded in 1968, five growing seasons after planting. As 

 previously mentioned, there were seedlings with damaged terminals on every plot, but 

 one plot that was covered by grass on a warm southeast slope was especially hard hit 

 and about 50 percent of the live seedling terminals were clipped, nipped or cut. On 

 other plots where brush species predominated there were fewer damaged terminals. It 

 seems that either the deer or elk, or both, may congregate in these warm, open areas 

 where the snow is sometimes absent through the winter, or maybe it is shallower and 

 melts earlier in the spring. Only a small amount of damage on the plots of Test 4 was 

 attributed to rabbits and hares. 



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