On July 1, 1964, 45 days after planting of seedlings, the soil moisture percent 

 (dry weight) generally exceeded "field capacity" as estimated from 1/3 atmosphere tests 

 in the laboratory (figs. 7 and 8; Appendices IV and V). Moisture contents were well 

 above "field capacity" in the second area (B) and near "field capacity" in the first 

 area (A). Soil moisture was determined at three levels below the surface: 3 to 6 

 inches, 9 to 12 inches, and 15 to 18 inches. In all samples, the hand-weeded plots 

 appeared to show the greatest moisture recharge on September 1. Recharge was consider- 

 ably less (or slower) under both polyethylene and glass fiber mulches. In some cases 

 a recharge was not evident until the measurement of October 1. Such a recharge 

 undoubtedly stemmed from lateral movement of soil water under the mulches. 



Temperature profiles (°F.) at the Boise Basin study area were determined on 

 August 4, 1964. Maximum air temperature recorded at the Weather Bureau Station at Idaho 

 City on this date was 91°; the minimum was 40°. The sun was at its zenith between 12:40 

 and 12:45 p.m., m.s.t. Relative humidities ranged from a high of 84 percent to a low of 

 18 percent. The wind had an average velocity of 10 miles per hour and was out of the 

 west. There were no clouds that day. 



Temperatures were slightly higher on the slopes that were most nearly at right 

 angles to the sun. Highest temperatures occurred at the soil surfaces (100.8° to 

 149.5° F.). Temperatures between the surface and 0.5 foot above the surface were high- 

 est over black polyethylene (149.5° to 96.5° F.). Glass fiber had the lowest maximum 

 surface temperatures. Highest temperatures were reached sooner on the surfaces than 

 above them. 



Live seedling tallies were made on the 1st and 15th of each month from June to 

 October 1964. The first mortality was noted July 15 (table 5). Fall tallies were con- 

 tinued annually until 1968 (Appendix II). The variation in survival of seedlings due 

 to areas was amazingly low (Appendix VI). Treatments differed significantly (p = .95) 

 in 1964 and 1965, but not in the remaining years. The undisturbed treatment had the 

 poorest rate of seedling survival in all years. Through 1965, the other three treat- 

 ments showed some differences as to seedling survival. In 1966, and later, the yearly 

 differences in survival were slight; this apparently was the reason for a lack of 

 significance in the treatments during these years. 



Table S. --Seedling survival (peroent) by treatments , July to 



October 1964^ Test 5 



Treatment 



Date of seedling tally 





7/I5I 



i 8/1 



f 8/15 i 



9/1 



• 9/15 : 



10/1 



Glass fiber mulch 



100 



100 



100 



100 



100 



100 



Polyethylene mulch 



100 



100 



100 



96 



94 



92 



Hand weeded 



100 



100 



96 



92 



90 



86 



Control (no mulch) 



98 



98 



92 



86 



82 



82 



25 seedlings planted in each cell. 



13 



