REVIEWS 367 



rather than by site and density and then assumes that the growth 

 shown, may be used as an indication of the growth under different 

 site and density conditions. A table showing differences in growth 

 under different site and density conditions would be of far greater 

 service than one showing differences in growth in different locali- 

 ties. The comparison is not of scientific value, because the marked 

 differences in locality may be due to site or density. 



An interesting point in regard to the culmination of the height and 

 diameter growth is brought out in the following paragraph (page 27) : 



"It appears from the diameter-growth table that the maximum 

 current diameter growth occurs between 80 and 100 years, which is 

 also the period of maximum height growth. The maximum average 

 annual growth for this 20-year period is 0.37 inch. The rate of 

 growth in diameter decreases less rapidly, however, than the rate of 

 height growth, the current annual exceeding the mean annual 

 growth up to about the hundred and forty-fifth year. Usually 

 the height growth of a tree species culminates before the diameter 

 growth. Whether the sustained rate of height growth apparent in 

 this species is attributable to the fact that the trees measured grew 

 in virgin forest, where their light requirements were not satisfied 

 during youth, or whether this is an inherent peculiarity, has not yet 

 been fully determined, and cannot be until older, more normal 

 second-growth stands are available for study." 



Another striking feature of sugar pine is the great age to which 

 it sustains its volume growth (page 27) : 



"The current annual volume growth remains above the mean annual 

 growth for over 400 years, over 300 years after the height and 

 diameter growth have culminated. At 100 years of age the annual 

 rate of volume growth is 2 cubic feet. It then increases steadily up 

 to an annual rate of 5I/2 cubic feet at 3.50 years. The rate of volume 

 growth remains practically constant from that age up to 460 years'. 

 No information to indicate its behavior at a greater age has been 

 collected." 



Tables showing yield and increment on one quality of soil (II) 

 for all species together are given for the two types in which sugar 

 pine occurs (page 29). The method of constructing these tables is 

 not explained, and no figures are given to show the approximate 

 percentages of the different species in the mixture. From these 

 tables the yield in the fir-sugar pine type apparently culminates at 

 340 to 350 years. This extreme age for culmination of yield is 



