GROWTH IN VOI.UMK. ' 37 



more slender trees, a factor of 0.45 being about the average for (renteiiarians — that means the 

 volume of a hundred year old tree is forty live one-liundredtlis of a cylinder of the diameter, 

 measured at breast height and the height of the tree. 



This factor varies, of course, according to the ratio between diameter and hoiglit, and since in 

 codominant and oj)i)r('ssed trees this ratio is a dirt'erent one from that of dominant trees, as we have 

 seen, their factor of shape is also different from that for dominant trees, tliat is, tluiir taper differs, 

 the former being more cylindrical than the latter. This will appear from a comparison of the 

 taper of trees as recorded in Table 11 of the. Appendix, in which small diiuiietcrs with comjiiira 

 lively long shafts indicate the codominant and supi)ressed trees. Those witli short lengths and 

 large diameters are trees grown in open stand. 



From Table II, Ai)pendix, we also see that the taper varies within wi<le limits from less than 1 

 inch to 5 inches for every 1<> feet, although in the majority of cases it lies between 2 and ."5 inches. 

 The tops taper, to be sure, much faster than the middle portion; and, again, in older trees espe- 

 cially, the butt logs much faster than the ujiper portions, which are outside of the influence of the 

 root swelling. 



In young trees which make three log lengths of 16 feet, it will be safe to allow Ih inches for 

 the first two logs and 2 inches for the last one as the average taper. In medium sized trees, 

 making four to five log lengths, an allowance of 2 inches on the whole will fairly represent the aver- 

 age taper, or one-eighth of an inch for every foot in length. In old trees which furnish five and six 

 or more logs, an allowance of 4 to r> and even 7 to S inches must be made for the first log and '.i to 

 4 inches for the two top logs, while the middle portions show a more regular and less variable 

 taper of about 2 inches, or one-eighth of an inch per foot. 



GROWTH IN VOLUME. 



During the juvenile stages the volume growth of the White Pine, as of most" trees, is insig- 

 nificant, a dominant tree of twenty years measuring not more than 0.5 cubic foot, which means an 

 average accretion of 0.025 cubic foot per year. For the third decade the amount of wood formed 

 is over three times what it was during the first two decades, and at fifty years the bole of a domi- 

 nant tree may contain from 10 to 11 cubic feet and over, the average annual accretion having 

 come up to one-fourth of a cubic foot, or ten times what it was at twenty years. 



Now, after the rapid height-growth period, with fully developed crowns, a rapid rate of 

 volume growth sets in, increasing with each year, in arithmetical progression, until at sixty to 

 seventy years the current accretion has become 1 cubic foot and over, and at one hundred years 

 as much as 1^ cubic feet is attained. After the one hundred and twenty-flfth year the increase 

 in the rate abates, yet before the second century it has become 2 cubic feet, and remains then 

 practically stationary for another century at least. 



Some of the oldest trees (four hundred and fifty years and over) measured contained 600 to 

 800 cubic feet of wood in the stem alone, the largest, with 855 cubic feet, indicating an avenige 

 annual accretion for this long life of over 1.8 cubic feet. 



While the current annuiil accretion after the fiftieth year is rapidly increasing, the average 

 annual accretion, affected by the earlier .stages of slow growth, increa.ses naturally more slowly. 

 For the first one hundred years the average is about two-thirds to three-fourths of a cubic foot 

 for dominant jiine, making the volume about 70 cubic feet. It increases to 1 cubic foot at one 

 hundred and fifty years and 1:^ cubic feet at two hundred years, and, as shown above, gains 

 gradually until old age. 



The i>rogress in volume growth naturally varies under different soil conditions and with tree 

 classes. In a general way, the oppressed trees and those on poorer sites do not begin the period 

 of rapid volume growth as early as the dominant classes, but just as in the height growth, which 

 is similarly delayed, the rate when once at its maximum persists with great uniformity until 

 about the one hundred and fortieth to one hundred and sixtieth year, when a decrease becomes 

 noticeable. 



The tables and diagrams in the Api)eudix show, by figures and graphically, the ])rogress of 

 diameter, height, and volume accretion for dominant, codominant, and opjiressed trees throughout 

 the range of the species. Comparing the growth from the several localities lepresented, a striking 



