Table 14 . --Chi-sguare test across diameter classes for best mortality equation for even- and 



uneven-aged blackjack pine using basal area growth equations for uneven-aged black- 

 jack pine only 



Diameter 



Number of trees 



Actual 



Predicted 



Chi-square 



class 



in class 



mortality 



mortality 



value 



4 



5,790 



126 



83.56 



21.6 



5 



5,635 



47 



70.76 



8.0 



6 



4,681 



28 



44.83 



6.3 



7 



3,549 



22 



25.58 



.5 



8 



2,540 



8 



13.96 



2.5 



9 



1,792 



7 



8.45 



.2 



10 



1 ,261 



6 



5.71 







11 



1 ,011 



6 



4. 30 



.7 



12 



893 



3 



3.62 



. 1 



13 



737 



2 



2.82 



.2 



14 



686 



1 



2.61 



1.0 



15 



666 



6 



2.71 



4.0 



16 



685 



4 



2.75 



.6 



17 



649 



2 



2.63 



.2 



18 



610 



1 



2.49 



.9 



19 



473 







2.05 



2.1 



20 - 21 



908 



6 



4. 15 



.8 



22 - 23 



622 



9 



3.03 



11.8 



24 - 25 



353 



1 



2.04 



.5 



26+ 



261 







2.34 



2.3 



Chi-square statistic = 64.3 



The finished mortality equations are in table 15. Graphs for some of these equations, using 

 representative values of the independent variables, are in figures 1, 2, and 3. Due to the 

 similarity of the two basal area growth equations for blackjack pine, only one of the two 

 mortality equations for uneven-aged blackjack pine and for even- and uneven-aged blackjack 

 pine were plotted. In all of the equations, the mortality rate increases as D and MBA2 

 increases and as BAG and TIME decreases. Caution should be taken when interpreting these 

 graphs. Because of the interrelationships among D, BAG, and MBA2, the actual mortality rate in 

 a stand would not be represented by any single curve shown. 



Conversion from Blackjack Pine to Yellow Pine 



The classification of ponderosa pine as either blackjack pine or yellow pine is based on 

 bark color. Young, vigorous growing trees have dark-colored bark while the mature or over- 

 mature, slow growing trees develop a yellow-colored bark (Harlow and Harrar 1958). As this 

 study has shown, the trees in these two "vigor" classes display different growth and mortality 

 rates and, as a result, an improvement in modeling growth and mortality can be expected if the 

 two vigor classes are treated separately. By treating them separately, however, it then 

 becomes necessary to develop a model predicting the conversion from blackjack pine to yellow 

 pine . 



16 



