Table 5. --Mean maximim recorded temperatures (°F.) at muldh surface 

 and beneath mulch ^ 8/5/62 and 8/7/63 



Mulch 



East (11 



to 12 a.m.) 



■ West (2 to 



3 p.m.) 



• Mulch 

 '• surface 



: Soil 

 : beneath 

 : mulch 



• Mulch : 

 : surface : 



Soil 

 beneath 

 mulch 







- - Degrees 



Fahrenheit- - 





Glass fiber 



141.8 



123.7 



133.8 



115.8 



Polyethylene 



149.7 



131.2 



141.6 



128.4 



None (soil surface) 



147.8 





142.0 





Animals interfered with the mulch materials, but no mulches were completely re- 

 moved. Deer, elk, and squirrels were the presumed culprits. In other tests, no mulch/ 

 terminal damage relationship was evident. This leads one to believe that there is a 

 low probability for such a bias in this test. I can only guess at the animal/vegeta- 

 tive cover/damage relationship. 



Seedling heights were measured in 1967 at the end of five growing seasons after 

 planting. Some of the seedlings had damaged terminals and were excluded from the 

 analysis. Twenty-eight of the 31 damaged seedlings were on one plot which had grass 

 cover but little brush. Other plots had predominantly brush cover. The number of un- 

 damaged seedlings and average heights for each treatment, both east and west aspects 

 combined, were: 



Treatment Seedlings Height 



(Number) (Feet) 



Glass fiber mulch 107 0.93 



Polyethylene mulch 67 1.10 



Control (no mulch) 52 .86 



Test 4: PitSj Synthetic Mulches, and Simazine 

 on Two Aspects:, 1964 



A second test of the glass fiber and polyethylene mulches was made at Zena Creek 

 in 1964. It was believed that relative effects of the mulches, the weather and, per- 

 haps, the interactions, could be gaged by using something other than a mechanical mulch 

 to eliminate competing vegetation. The pre-emergence herbicide simazine was selected 

 to provide this weed-free condition; it was assumed that simazine would not directly 

 affect seedling growth. Thus, the four treatments were: (1) black polyethylene mulch; 

 (2) glass fiber blanket mulch; (3) simazine herbicide application; and (4) control (no 

 treatment other than the pit) . 



East and west aspects were again compared by using four replications on each aspect 

 Average soil depths on the eight plots ranged from 21 to 31 inches to bedrock. Two 

 hundred seedlings were planted in each of the eight plots, 50 seedlings per treatment 

 (total of 1,600 seedlings). 



"t" tests of mean heights showed no significant differences. 



9 



