associated and express the potential storage of moisture. Higher storage 

 of moisture should be associated with higher tree vigor and lower beetle 

 risk susceptibility class. Indicators of soil depth and texture can be 

 secured by observing land forms, kinds of materials underlying the soil, 

 observations of deep road cuts, uprooted trees, mapping experience in the 

 general area, and published soil survey reports. Important preliminary 

 qualitative data on soils was quickly collected and first stratification 

 of data was made. For qualitative determination of soil moisture it is 

 expected that pits would eventually be dug in the plots, the soil profile 

 described in detail, and samples taken for laboratory determination of 

 moisture points, and fertility factors. At that time, detailed mapping 

 of soil in the plots would be made in order to check soil uniformity and 

 variation. 



Another facet of the study sought information on the radial growth rates of mature 

 ponderosa pine trees representing different risk ratings. This was done cooperatively 

 with the School of Forestry of the University of Montana. Increraent cores were extracted 

 from 383 risk rated ponderosa pine trees at breast height on four plots. Mean tree 

 ring widths for the last 10 years (1944-1953) were calculated for cores representing 

 each risk rating group and comparisons were made of these means. 



By 1958 it was apparent that objectives of the study could not be attained within 

 10 years because of continuing low levels of pine tree mortality that resulted from 

 the endemic populations of the western pine beetle and the mountain pine beetle that 

 persisted during the period. By agreement with cooperators , the study was continued 

 for a second 10-year period. Hopefully, tree mortality from the two pine beetles would 

 be sufficient at the end of this extended period to realize objectives of the study. 



Extending the study posed a new question. Would the initial risk ratings continue 

 to be valid during the second 10 years of the study? Changes in the initial risk rat- 

 ings of some pine trees had been noted by research personnel throughout the first 10 

 years of the study. To ensure valid ratings during the second 10 years, the pine trees 

 on 17 plots established before 1952 were re-rated in 1964 and 1965. This was done by 

 trained forestry research technicians under the close supervision of the research 

 entomologist in charge of the study. This procedure hopefully afforded continuity as 

 well as a minimum of personal bias in the ratings. 



6 



