GROWTH IN VOLUME. 37 



more slender trees, a factor of 0.45 being about the average for centenarians— tbat means the 

 volume of a Imndiedj ear-old tree is forty-five one-Iiundredths of a cylinder of tlie diameter, 

 measured at breast height and the height of the tree. 



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

 codominaut and oi)])ressed trees this ratio is a different one from that of dominant trees, as we have 

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

 the former being more cylindrical than the latter. This will api)eai- from a comi)arison of the 

 taper of trees as recorded in Table II of the Appendix, in which small diameters with comjiara- 

 tively long shafts indicate the codominant and suppressed trees. Those with short lengths and 

 large diameters are trees grown in open stand. 



From Table II, Appendix, we al.so see that the taper varies within wide limits from less than 1 

 inch to 5 inches for every IG feet, although in the majority of cases it lies between 2 and 3 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 upper pcn-tions, which are outside of the intiuence of the 

 root swelling. 



In young trees which make three log lengths of 10 feet, it will be safe to allow 1.^ 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 faiily 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 5 and even 7 to 8 inches must be made for the first log and 3 to 

 4 inches for the two top logs, while the middle ))ortious 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, whicli 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 14 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 li cubic feet is attained. After the one hundred and twenty-fifth 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 average 

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



While the current annual accretion after the fiftieth year is rajjidly increasing, the average 

 annual accretion, affected by the earlier stages of t^low growth, increases naturally more slowly. 

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

 for dominant jjine, 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 progress 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 Appendix show, by figures and graphically, the i)rogress of 

 diameter, height, and volume accretion for dominant, codonunant, and ()i)pressed trees throughout 

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



