A NATIONAL PLAN FOE AMERICAN FORESTRY 



905 



earnings, discussion is based on the assumption that this system of 

 selection or partial cuttings will be followed in virtually all private 

 forestry. It is recognized, however, that certain species such as 

 Douglas fir, most of the pines, yellow poplar, white ash, and many 

 oaks will not regenerate except in full or nearly full light. Therefore, 

 the selection system as here contemplated includes "group selection" 

 meaning that when regeneration of light-demanding species becomes 

 necessary openings will be made in the stand, varying according to 

 the species, the locality, the site, and the stand conditions from 

 about one sixty-fourth of an acre to 5 acres in extent. In a few regions 

 such as the Douglas fir region where regeneration comes easily and 

 early growth is rapid, openings may occasionally be as large as 25 

 acres or in exceptional cases even larger. Data on growing-stock 

 conditions in representative types and regions are presented with the 

 understanding that the average acre given represents conditions in 

 stands now on a selective basis or, where the stands are even aged, 

 that the suggestions for treatment contemplate conversion to that 



FIGURE 2. Selection forest. 



basis. The data and suggested treatment can be most readily visual- 

 ized if thought of as applying to a forest area division of 25 to 200 

 acres, usually termed " compartment." The treatment recommended 

 contemplates that every such compartment in a forest property shall 

 at all times be stocked to the best advantage^ with trees of a certain 

 diameter range, for most species from 6 to 40 inches or more, capable 

 of laying on annual growth .of high value. 



The selection system has certain subsidiary advantages. It is 

 safer from fire. Intensive research in various regions, notably the 

 Northeastern, the North Rocky Mountain, and the Pacific coast, 

 have proved that forest litter is inflammable a much larger portion of 

 the time in the open than in the shade. In effect, in the forest the fire 

 season is shorter. Also, larger trees are not so easily damaged by 

 fire and can maintain a considerable rate of growth for the stand 

 even if some smaller trees are occasionally killed by fire. Wind 

 velocities are diminished by the larger trees, and fire is more easily 

 controlled owing to this factor and to the fact that the low crowns of 

 the young trees do not occur over large continuous areas. 



Another advantage is that it is not necessary to cut trees of all 

 sizes simultaneously; cuttings can be regulated according to market 

 demands. The forest well organized on this basis is like a well-ordered 

 warehouse in which the owner can take any goods he desires off the 



