930 
Journal of Agricultural Research, 
Vol. XXXI, No. 10 
last-named species becomes more abundant with an increase in ele¬ 
vation, taking the place of hemlock and Douglas fir, these species 
dropping out. Noble fir and Douglas fir form the dominant crown 
classes, hemlock occurring mainly as an understory. In point of 
numbers, hemlock forms about 60 per cent of the stand, noble fir 
and Douglas fir about 20 per cent each; according to volume, how¬ 
ever, noble fir forms 46 per cent, Douglas fir 24 per cent, and hem¬ 
lock about 30 per cent. The crown canopy varies from 0.8 to 0.9 
in point of density for the upper story, which, coupled with the canopy 
of the suppressed hemlock, casts a rather dense shade. This is 
probably the main reason for the almost total lack of underbrush, 
except where the crown has been opened owing to windfall or death 
of the dominant trees. 
Q II- ------------- 
O 20 -40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 
AGE IN YEARS 
Fig 1.—Diameter-growth curves for noble fir, Douglas fir, and western hemlock 
THE TREE AND ITS MANAGEMENT 
Noble fir in this locality forms a tall, straight, cylindrical bole with 
a comparatively small and open crown. The trunk prunes itself 
readily of side branches, indicating the rather intolerant nature of 
the tree; the length of the crown being only about one-third to one- 
fourth of the total height. Trees were found up to 6 feet in diameter 
at breast height, attaining a maximum height of about 215 feet. 
The average tree, however, has a diameter of a little more than 4 
feet, and an average height of close to 200 feet. 
