PINE TREES OF ROCKY MOUNTAIN REGION. 41 
coast form is rather heavy, being about 36} pounds, while wood of 
the Rocky Mountain form weighs about 254 pounds per cubic foot. 
Tangentially (“bastard”) cut boards have a distinctly pebbled 
appearance when planed. 
In the Rocky Mountain region the wood of this tree is becoming 
more and more valuable for commercial purposes, which include 
construction lumber, much used locally, and railway ties. It is also 
used for corral poles, house logs, and fuel. In the Pacific region it 
is used principally for these latter purposes. 
OCCURRENCE AND HABITS. 
In the Rockies Pinus contorta occurs on high plateaus and benches 
in the vicinity of streams, mountain meadows, and lakes, on broad 
ridges, and on long gentle slopes and bottoms of stream-watered 
basins at elevations between 7,000 and 11,500 (Map No. 13). North 
and east slopes are more favorable than west slopes, while south 
slopes, except in sheltered coves, are least favorable for the growth 
of this pine. It avoids limestone, but is adapted to dry gravelly 
soils, seeming to prefer sandy moist ones of gentle slopes, depres- 
sions, and plateaus, where the largest growth occurs. Stunted forms 
erow persistently, however, in crevices of solid rock. It forms ex- 
tensive pure forests, particularly about meadows; on higher, rocky, 
rough ground it is sometimes associated with Engelmann spruce, 
aspen, Douglas fir, and alpine fir. 
The lodgepole pine is very intolerant of shade, especially when 
young, but is able to maintain itself for a long time (from 20 to 50 or 
| more years, or for a longer period) in very dense stands, after which, 
| if wholly relieved from overhead shade, it recovers and grows rapidly. 
It grows best, however, in full enjoyment of light. Even-aged, 
dense stands with full top light, such as commonly follow complete 
destruction of the preceding growth by fire, may thrive for 50 or 60 , 
| years with little natural thinning out. But the prompt natural 
_ thinning out of overtopped trees at earlier stages in uneven-aged 
| stands is proof that this pine is unable to endure longer continued 
| shade. 
_ This species is usually a prolific annual seeder, bearing large num- 
| bers of cones. The seed has a high rate of germination and persistent 
| vitality. Fertile seeds are often borne by trees only from 6 to 10 
_ years of age when growing in the open. In crowded stands cones 
| are borne by trees from 15 to 20 years old. The small light seed is 
| widely disseminated by wind, sometimes being carried 200 yards 
_ from the mother trees. Squirrels and birds destroy great numbers of 
_ the seeds, but the effect on reproduction appears to be inappreciable. 
| Extension by natural seeding on unburned areas is ordinarily slow, 
