_ LIFE HISTORY OF LODGEPOLE PINE IN ROCKY MOUNTAINS. 7 
increased growth after being released from suppression. For its 
best development lodgepole requires considerable light from above. 
With full sunlight as standard, no vigorous seedlings were found in 
Colorado in light values of from 0.08 to 0.05. Since the light values 
in mature forests range from 0.12 to 0.05, with an average of 0.08 
or 0.07, it is obvious that satisfactory reproduction can not be ex- 
pected in such stands.1. Seedlings often start under the partial shade 
of moderately open stands, particularly in restricted groups in small 
openings, but their growth and development is slower than in the 
open. Full sunlight will result in the best development at all ages, 
provided sufficient soil moisture is available. In the order of their 
tolerance the species of the lodgepole region may be grouped as fol- 
lows: Alpine fir, Englemann spruce, Douglas fir, white bark pine, 
lodgepole pine, yellow pine, limber pine, juniper. 
Although not as tolerant as most of its associates, lodgepole is 
truly remarkable for its ability to live for long periods in a badly- 
suppressed condition in the shade of larger trees of the same species. 
It is this characteristic which makes dense reproduction undesirable. 
The extremely dense stands which follow fire will remain dense in- 
_ definitely to the practically complete stagnation of growth. Some 
stands over 50 years old have more than 50,000 live trees per acre 
from 8 to 10 feet high. On Buffalo Creek on the Deerlodge National 
Forest, Mont., in a 70-year-old stand on a north slope, a count on 1 
square rod in a fairly typical situation showed a density at a rate of 
101,000 live trees per acre, together with 79,000 dead ones. (PI. I 
fig. 2.) The “trees,” which could be pulled up like so many weeds, 
had an average diameter of about three-tenths inch at 1 inch above 
ground and a height of about 4 feet. The largest tree was 8 feet 
high and 1.5 inches in diameter. The wonderful persistence of the 
individual is shown by the loss of only 45 per cent in numbers after 
10 years of crowding. This behavior of lodgepole, which is evident 
in Colorado and Wyoming, as well as in Montana, contrasts strongly 
with that of yellow pine, an area of which near Missoula, Mont., 
showed only 1,300 live trees per acre after 30 years in a stand which 
had originally numbered 3,500 trees per acre. Of the surviving trees, 
moreover, 310 completely Josnueunea the rest. 
In overdense stands of lodgepole the side branches are killed by 
shading for the better part of the distance up the bole. In moder- 
ately dense stands, however, natural pruning of the side branches is 
not extensive enough to result in the production of clean stems. It 
has been estimated that reproduction at the rate of about 8,000 seed- 
lings per acre is necessary to secure a high degree of natural pruning. 
In a stand of 1,500 to 2,000 seedlings per acre, well distributed, the 
lower side branches will remain small and die at an early age. Many 
1 Forest Service Bulletin 79, History of Lodgepole Burn Forests, and Forest Service 
Bulletin 92, Light in Relation to Tree Growth. é 
