RISK RATINGS OF BEETLE KILLED PONDEROSA PINE TREES 



Approximately three of every four of the 132 ponderosa pine trees killed by 

 Dendroatonus bark beetles on the plots since the start of the study were either Risk 3 

 (high risk) or Risk 4 (very high risk) trees (see table 10). The proportion of the high 

 risk trees (Risk 3 and Risk 4 together) among the total number of beetle-killed pine 

 trees varied from plot to plot. In 20 of the 22 plots, however, high risk beetle-killed 

 trees exceeded low risk beetle-killed trees (Risk 1 and Risk 2 together) both in their 

 number and board-foot volume (table 11). 



From the pooled data in table 10, it is evident that Risk 2 trees were almost as 

 numerous as Risk 4 trees among all the trees killed by pine beetles on the plots. The 

 38 Risk 2 trees, however, came from a substrate that was 39 times larger than that from 

 which the 40 Risk 4 trees came (table 3) . This suggests that Risk 4 trees would be 

 killed by pine beetles sooner than an equal number of Risk 2 trees. 



Table 10 .- -Distribution by risk ratings of ponderosa pine trees 

 killed by bark beetles from 1948 through 2968 on 22 

 plots not subjected to sanitation- salvage cuttings 



Risk ratings 



Trees 



Volume 



Number 



Percent 



Board feet 



Percent 



1 (Low) 



2 (Moderate) 



3 (High) 



4 (Very high) 



1 



38 

 53 

 40 



0.8 

 28.8 

 40.1 

 30. 3 



24,520 

 43,800 

 34,820 



220 



0.2 

 23.7 

 42.4 

 33.7 



Total 



132 



100.0 



103,360 100.0 



