Dec. i 5 ,1925 Yield Capacities of Yellow Pine Type in California 1135 
the western forest regions, but is probably higher than the yield in 
most of the subdivisions of the western yellow pine region. A rotation 
of about 120 years is indicated. However desirable shorter rotations 
may be, it does not appear that they can be realized and at the same 
time obtain the largest possible annual growth. 
In the technique of the study several departures have been made 
from conventional practice. Of these perhaps the most important 
are (1) the use of dominant mature heights in the virgin forest as 
indices of site, (2) measurement of only a few heights on each plot, and 
construction of height-diameter curves for each as a basis for volume 
computations; (3) determination of ages by means, of the increment 
borer; (4) employment of a log rule giving the actual merchantable 
contents of logs; and (5) adoption of standards of utilization not now 
in effect, but to be anticipated as effective when stands now young 
are utilized. 
