Ingrowth. - -Another important source of volume increment in partially cut stands is con- 

 tained in trees smaller than merchantable size (9.6 inches d.b.h.) at logging that subsequently 

 grow into merchantable size. These trees are not measured in board-foot volume until they 

 reach the 10-inch d.b.h. class. Ingrowth contributed very little volume increase for Engelmann 

 spruce, but comprised nearly half of the gross volume increment for subalpine fir. Ingrowth of 

 Engelmann spruce did not appear until the 21- to 25 -year period after logging, but the ingrowth 

 of subalpine fir became part of the merchantable stand within 6 to 10 years after logging and 

 continued to increase over the period. The subalpine fir, although small, were old and had 

 approached or passed their peak vigor. 



STATUS AND PROGRESS OF NATURAL REPRODUCTION 



The primary objective of regeneration cutting is to establish a new stand by natural re- 

 generation. This entails providing an adequate seed source, an effective seedbed, and other 

 site and climatic conditions favorable to seedling establishment. In discussion of natural regen- 

 eration the area will be referred to in three units, namely: (1) partial cutting, (2) clearcut basin 

 unit, and (3) clearcut slope unit (fig. 1). 



Seed source.- -A seed source may be provided by leaving scattered seed trees, shelter- 

 wood in partial cuttings , or uncut timber margins surrounding clearcut blocks, strips, or 

 patches. In this study a shelterwood remained in the partial cutting. The seed source in the 

 clearcuttings was contained in groups of 15 to 20 seed trees, 1 -chain-wide strips, and two 

 1-acre blocks of seed trees. In 1929, about 5 years after the last cutting, Dejamette® carefully 

 examined the condition of the seed source. He reported very heavy mortality, largely windfall, 

 of mature trees in the strips and seed-tree groups. Of the total number of seed-tree groups 

 left, only 38 percent retained one or more live trees. Out of 30 groups which were identified 

 and examined in detail, about half had one -fourth or fewer of original trees surviving, one -third 

 of the groups had between one -fourth and one -half of the trees surviving, and only one -sixth of 

 them had as many as one -half or more of the original number surviving. Dejarnette also re- 

 ported similar results in the strips. By 1954 it was practically impossible to identify any of the 

 seed-tree groups or the strips. However, enough surviving trees were present to identify the 

 two 1-acre blocks. 



Analysis of the 1954 data shows evidence of seeding in the clearcut units from the sur- 

 rounding uncut timber. The mean number of trees per acre in reproduction 2.6 feet and taller 

 was 369, based upon plots that fell within 10 chains of the timber edge- -as compared with only 

 250 trees per acre beyond 10 chains from the timber edges. The difference of 119 trees was 

 significant at the 5-percent level in "t" tests. Because of the early loss of much of the seed 

 source left within the clearcut areas after logging, it is doubtful whether that source contributed 

 much seed for reproduction. 



Seedbed. - -Differences among seedbeds after 30 years could not be readily distinguished 

 in 1954. Some skidroads and soil bared by upturned roots were still discernible. Skidroads 

 could be identified by the reproduction on them and impressions in the ground. However, most 

 of the areas disturbed by the logging operations had been completely clothed by trees and other 

 vegetation, particularly Menziesia ferruginea, commonly known as buckbrush, which is the 

 predominant shrub now. 



6 Op . cit . 



8 



