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.—LHffect of density on yield per acre of lodgepole pine, Deerlodge 
National Forest, Mont. 
: Diameter of av- 
Trees per acre. Yield. Ratio erage tree. 
of ‘ 
board Heian 
Scale timber, | feet,6 2 2Ver 
Sample plot. Age. top diameter, | inches ee 
: inside bark, to—| top di- e ‘ 
Entire | Main | moo) ameter,| (dbh.8) All | Main 
stand. | stand.1 - |__| cubic! 12-)- | trees. | stand.1 
6 8 feet. 
inches. | inches. 
Years.| No. No. Cu. ft. | Bd. ft. | Bd. ft. Feet. | Inches. | Inches. 
[28 Bae ey 8 110 501 293 4,187 | 10,542 3,217 2.52 59 Wee 8.4 
Foz AS a} GY oie 109 701 325 5, 441 8, 682 1, 580 1.60 67 6.5 8.1 
3S ae Se 109 764 338 | 6,286 | 19,440 | 4,387 3.09 71 6.6 8.4 
ee at gee Shes) 108 810 338 7,331 | 20,400 2,456 2.78 72 6.6 8.6 
i ley fry ea a 107 960 250 5,614 | 15, 260 1,190 22 69 Oud 7.9 
(ee ae tae 107 987 303 6,178 | 12,070 1,610 1.95 69 5.9 7.8 
#5 Se Sasa ee 107 1, 249 149 5, 080 24980 iS oe sea . 59 67 5.0 liao 
‘1 See iy ee 104 1,495 124 4, 840 DEASO st eiteek oe shall 57 4.7 hee 
US ect Aa eee 101 1, 564 124 | 4,668 | 2,480 |.-.....- = (33 58 4.6 let 
UL ee SE ee ee 105 1,805 73 4,405 P4600) 5-5-8 5333 57 4.2 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. 
