LIFE HISTORY OP 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 

 70 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 dominated 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 steins. 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. 



