ENVIRONMENTAL CONDITIONS 

 DURING THE STUDY PERIOD 



Weather Factors 



No weather records were kept on the planting site during the study period. Instead, 

 the precipitation and temperature records from the Avery Ranger Station (6 miles north 

 and 2,500 ft. lower in elevation) were used to provide a year-by-year comparison of 

 general conditions similar to those at the planting area (€ig. 1) . 



Weather during the 1966 and 1967 fall plantings was similar, and characterized by 

 relatively sparse precipitation, some rather long dry spells, and high temperatures. 

 By comparison, the 1968 fall plantijig weather was very moist and temperatures were low. 

 Precipitation during the 1967 and 1968 spring planting seasons was fairly abundant and 

 well distributed. Although abundant, precipitation during the 1969 spring planting 

 season was less uniformly distributed; a 20-day dry spell was recorded from June 1 to 20. 

 Summer weather during the 3-year period was highly variable. The summer of 1967 featured 

 one of the longest and hottest dry spells on record, climaxed by the disastrous Sundance 

 and Trapper Creek forest fires in northern Idaho. The relatively moist summer of 1968 

 had only one drought, a 23-day period during which less than one-fourth inch of rain 

 fell. The summer drought of 1969 was as severe as that in 1967, but lacked the high 

 temperatures common in 1967. - 



Soil Moisture 



At no time, was the soil moisture in the 4- to 8-inch zone below the wilting point 

 (21 percent) when trees were planted (table 1) . Soil moisture content on the moist 

 sites was always 10-40 percent higher than on the dry sites. In general, there was a 

 steady increase in moisture percentage throughout the fall planting season. 



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