LIFE HISTORY OF LODGEPOLE PINE IN ROCKY MOUNTAINS. 



29 



partly mature, and partly overmature. In Wyoming and Colorado 

 there is a much larger proportion of mature, and especially over- 

 mature, lodgepole stands, a difference which leads to the conclusion 

 that in the past fire has been less prevalent in Colorado and Wyoming 

 than in Montana. 



YIELD. 



FACTORS INFLUENCING YIELD. 



The yield per acre of any stand varies with its age, density, and 

 the quality of the site on which it grows. Ordinarily the better sites 

 and older stands produce the heaviest yields, provided deterioration 

 has not set in. With lodgepole, however, the yield, particularly in 

 board feet, is determined more by the density of the stand than by 

 either its age or the quality of the site. It is not unusual to find 

 young, properly stocked stands of lodgepole with larger yields than 

 older, overstocked stands on better sites. The effect of density on 

 yield is illustrated in Table 6, which gives the results of measure- 

 ments of 10 sample plots, all of approximately the same age. 



Table 6. — Effect of density on yield per acre of lodgepole pine, Deerlodge 



National Forest, Mont. 





Age. 



Trees per acre. 



Yield. 



Ratio 

 of 



board 



feet, 6 

 inches 

 top di- 

 ameter, 

 to cubic 



feet. 



Height 

 of aver- 

 age 

 tree 

 (dbh. 8 

 in.). 



Diameter of av- 

 erage tree. 



Sample plot. 



Entire 

 stand. 



Main 

 stand. 1 



Total. 



Scale timber, 



top diameter, 



inside bark, to — 



All 

 trees. 



Main 

 stand. 1 





6 



inches. 



8 

 inches. 





Years. 

 110 

 109 

 109 

 108 

 107 

 107 

 107 

 104 

 101 

 105 



No. 



501 



701 



764 



810 



960 



987 



1,249 



1,495 



1,564 



1,805 



No. 

 293 

 325 

 338 

 338 

 250 

 303 

 149 

 124 

 124 

 73 



Cu.ft. 

 4,187 

 5,441 

 6,286 

 7,331 

 5,614 

 6,178 

 5,080 

 4,840 

 4,668 

 4,405 



Bd.ft. 



10, 542 



8,682 



19,440 



20, 400 



15, 260 



12, 070 



2,980 



2,480 



2,480 



1,460 



Bd.ft. 

 3,217 

 1,580 

 4,387 

 2,456 

 1,190 

 1,610 



2.52 



1.60 



3.09 



2.78 



2.72 



1.95 



.59 



.51 



.53 



.33 



Feet. 

 59 

 67 

 71 

 72 

 69 

 69 

 67 

 57 

 58 

 57 



Inches. 

 7.2 

 6.5 

 6.6 

 6.6 

 5.7 

 5.9 

 5.0 

 4.7 

 4.6 

 4.2 



Incites. 

 8.4 



2 



8.1 



3 



8.4 



4 



8.6 



5 



7.9 



6 



7.8 



7 



7.5 



8 



7.3 



9 



7.5 



10 



7.4 







1 Includes all trees 7 inches and over in diameter, breast high. 



The table shows that an increase in the number of trees per acre 

 beyond a certain point results in a marked decrease in the number of 

 trees which will make scale timber, in the average diameter and 

 height, and in the yield, especially in board feet. Much denser 

 stands existed than any of those shown in the table, with corre- 

 spondingly smaller yields. One plot 160 years old, for example, con- 

 tained approximately 3,500 live trees per acre, not more than 4 

 inches in diameter. Such a stand produces only lagging poles. 

 Other stands of the same age are still denser, producing nothing of 

 value. 



