RISK RATINGS OF LIVING PONDEROSA PINE TREES 



Procedures followed during the establishment of 553 acres of plots resulted in 

 11,946 sawlog-size ponderosa pine overstory trees being risk rated. The gross volume 

 of these trees was 9,276,000 board feet. From this, it was possible to determine the 

 number and volume of pine trees in each of the four ratings. 



Distribution of Risli Rated Trees 



Least abundant were trees rated Risk 1. These trees presumably are the least 

 susceptible, or the most resistant, to attack by Dendroatonus bark beetles. They 

 accounted for about 13 percent of the number and 8 percent of the volume, respectively, 

 of the 11,946 risk rated pine trees (table 3). This paucity of low-risk trees also was 

 discernible in each of the overstory stands of the 35 plots (table 4) . 



Trees rated Risk 2 (moderate) were by far the most abundant. Seventy-two percent 

 of the number and volume of all the risk rated trees were in this category. Risk 2 

 trees, likewise, comprised a comparable proportion of risk rated trees in each of the 

 plot stands (fig. 4) . 



Trees rated Risk 3 were considerably more abundant than those rated Risk 4 but, 

 together, they made up 15 percent of the number and 20 percent of the volume, respec- 

 tively, of the 11,946 risk rated trees (table 3). Risk 3 and Risk 4 trees, collectively, 

 are the "high risk" trees of the risk rating system. They are the trees that sanitation- 

 salvage cuttings are designed to remove from ponderosa pine stands to prevent the buildup 

 in these stands of epidemic populations of bark beetles. 



Table 5. --Distribution by risk ratings of pooled sawlog-size ponderosa pine trees an 



35 plots in western Montana ^ 



Number of . Percent of . Gross volume . Percent of 



Risk ratings • trees . total number • (board feet) . total volume 



1 (Low) 



1,536 (2.8) 



12.9 



787,260 



(1,424) 



8.5 



2 (Moderate) 



8,628 (15.6) 



72.2 



6,640,970 



(12,009) 



71.6 



3 (High) 



1,533 (2.8) 



12.8 



1,583,390 



(2,864) 



17.1 



4 (Very high) 



249 (0.4) 



2.1 



264,740 



(478) 



2.8 



Total 



11,946 (21.6) 



100.0 



9,276,360 



(16,775) 



100.0 



^Figures 



in parentheses represent 



per-acre 



values based on 



a combined 



total of 



553 acres for the 35 plots. 



15 



