Figure 10. — Subalpine fir and 

 Douglas- fir seedlings 

 grow in stand openings 

 created by mountain pine 

 beetle infestations. 

 Moody Meadows area, 

 Targhee National Forest. 



When a portion of the stand dies it causes changes in light, temperature, moisture 

 accumulation, and soil moisture, among others, and thereby creates a new niche in the 

 environment. This ecological niche is soon filled by the growth of newly established 

 seedlings--chiefly more tolerant species--or the accelerated growth of existing trees 

 or other vegetation. The Dell Creek data are a good example of a stand in which the 

 displacement of lodgepole pine has progressed to aji advanced stage. During the period 

 of depletion the stand exists in varying degrees of mixtures of dead trees, green 

 residuals, and succeeding species. 



Stand structure in the Dell Creek stand, before stand depletion and accelerated 

 understory growth changed it, probably compared well with the present stand structure 

 in the younger Pilgrim Mountain stand (figure 6). Subalpine fir ranging from 6.7 to 

 18.7 inches in the present Dell Creek stand had a mean d.b.h. of 3.4 inches and a range 

 of 1.6 to 7,3 inches in the stand 80 years ago. The subalpine fir contained in the 

 present Pilgrim Mountain stand averages 3.8 inches d.b.h. and represertts a range of 1 

 to 21 inches in diameter. We have been unable to reconstruct the depleted lodgepole 

 pine stand in the Dell Creek area, but considering the volume of material on the ground 

 it appears to have been a well stocked stand. If we assume the same rate of lodgepole 

 pine depletion and subalpine fir understory growth on Pilgrim Mountain as occurred in 

 Dell Creek, it is conceivable that the Pilgrim Mountain stand could arrive at nearly 

 the same condition in about 80 years. 



Regeneration 



It is likely that many beetle-decimated lodgepole pine stands containing residual 

 seed trees with serotinous cones have burned over in the past and reseeded promptly 

 to establish new lodgepole pine stands. For example, the Sleeping Child Fire, touched 

 off by a lightning strike in 1961, burned in excess of 25,000 acres of lodgepole pine 

 and associated stands on the Bitterroot National Forest.^ This fire burned lodgepole 

 pine stands that had sustained heavy damage by a mountain pine beetle infestation from 

 1928 to 1932 when a large proportion of the dominant and codominant trees was destroyed. 

 Following the fire, a large part of the burn (over 15,000 acres) restocked naturally 



'^Office report, Northern Region, U.S. Forest Service, 

 mountain Forest and Range Experiment Station, Ogden, Utah. 



Report on file at Inter - 



15 



