78 BULLETIN 1105, U. S. DEPARTMENT OT AGRICULTURE. 



percentage of survival is not clear. Possibly there are differences 

 in quality of site which have not. been taken into account. Although 

 it is too early to predict the final outcome, it is worth while to point 

 out what seems to be the general bearing of developments up to 

 the present time. 



The scattered seed-tree method has already outstripped the group 

 selection method in both survival and development of seedlings, 

 and present indications are that it will maintain or even increase 

 this lead. The shelterwood method has a wide margin over the 

 other two methods in point of numbers, but it is distinctly below 

 them with respect to the size and vigor of seedlings now on the 

 ground. Future examinations will probably continue to show most 

 seedlings per acre on the shelterwood area, but they will be smaller 

 and less uniformly distributed than on the other two areas. It is 

 by no means certain that, all things considered, the shelterwood 

 method will not stand at the bottom of the scale two or three years 

 hence. 



In deciding which method of cutting should be practiced, the 

 requirements for natural reproduction must be harmonized with 

 existing natural and economic conditions, in so far as the latter are 

 incapable of modification. In the first place, the western yellow 

 pine forests in the Southwest are made up of several age-classes. 

 It is doubtful whether it will ever be practical or desirable to 

 change this arrangement, or at least we can not look toward such 

 a change within the next 50 years. When a stand is logged, there 

 are usually two or more distinct age classes which are either too 

 small to be merchantable or are growing so rapidly that it would 

 be poor business to cut them. Such trees, excluding undesirable 

 individuals, should be left, even though they may be detrimental 

 to reproduction in their immediate vicinity. Another circumstance 

 which must be taken into account is the expense of logging. It is 

 obvious that cuttings, however desirable silviculturally, can not be 

 executed unless the amount of material removed is sufficient to war- 

 rant the cost of transportation systems and other more or less fixed » 

 investments. With these conditions in mind, we are in a position 

 to decide which of the three methods of cutting, the group selec- 

 tion, the scattered seed-tree, or the shelterwood method, is best 

 adapted to attain the aims of forest management. 



The shelterwood method has little to commend it under the con- 

 ditions which must be met in present-day practice. In order to 

 realize the benefits of the plentiful seed supply and shelter to young 

 seedlings, which are the primary advantages of the method, the 

 mature trees should be removed within three years after the appear- 

 ance of the main seedling crop. This can rarely be done on account 

 of logging conditions. If the mature trees are not removed at the 



