384 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



Ill some stands the trees are for tlie most part of the same age, and 

 all mature. This is a common occurrence where, after fires, the burns 

 have been restocked by a stand of relatively even age. The selec- 

 tion system is not applicable to such conditions. In some cases the 

 best procedure is to remove the stand in two or more cuttings. The 

 first cutting is in the nature of a tliinning, which removes about 50 

 or (30 per cent of the stand. So far as possible, the trees left are 

 thrifty individuals which will make substantial growth during the 

 next twenty or thirty years. The design is to return after from ten 

 to thirty years and remove part or all of the remaining' trees. The 

 opening of the stand by the first cutting results in establishing a new 

 crop under the shelter of those left. This is called the shelter-wood 

 system. It has been used very extensively in the National Forests. 

 In the Black Hills, for example, even-aged yellow pine stands have 

 been cut in this way, with a removal of about 60 per cent of the stand 

 in the first cutting. The same method has been applied also in 

 stands of lodgepole pine and other species. 



In some instances, where practically all the trees are mature 

 and the conditions are such that the shelter-wood system is not 

 applicable, all of the stand is cut except a limited number of seed 

 trees, left either as scattered individuals or in scattered groups. 

 This system of clear cutting, with scattered seed trees, has been 

 used on a large scale on the Minnesota National Forest. It has 

 been in operation since 1904. From 5 to 10 per cent of the timber 

 is left to produce seed. The results have varied ; in some parts of the 

 Forest they have been very satisfactory ; in other parts less so. There 

 has been some windfall of seed trees, especially on the earlier cut- 

 tings; on the later ones a more skillful selection of the trees to be 

 left minimized the loss. On portions of the area reproduction is 

 coming in very successfully; on other portions slowly. Such defi- 

 ciencies call for supplemental planting to provide a full stand. The 

 chief obstacle to reproduction is the competition with brush and 

 other vegetation, which has sprung up very abundantly on the 

 clearings. The best results are obtained under this system if the 

 ground is burned over just before or during a seed year, since this 

 facilitates the establishment of a new forest growth in competition 

 with the other vegetation. 



Not uncommonly the danger from windfall is so great that any 

 system of thinnings of the stand is impossible. Under such circum- 

 stances it would not be practicable to leave individual trees or 

 groups of trees for seed distribution. A clear cutting must then 

 be made. If natural reproduction is relied upon, the clearings must 

 be small enough to allow the distribution of seed from the surround- 

 ing stands. A method which has been used is to cut the timber 

 clear in narrow strips. Where the topography is comparatively 

 uniform and logging difficulties do not prevent, strips from 100 to 

 300 feet wide are cut, each separated by a band of timber of approx- 

 imately the same width as the clear strips. This results in the 

 removal of about half of the timber. The design is to return 

 at a later date, after reproduction has occurred on the strips, and 

 remove and reproduce the intervening strips. At the time of the 

 second cutting, from ten to thirty years hence, it will be necessary 

 to resort to artificial reproduction if the danger from windfall is so 

 great that none of the systems of natural reproduction is apphcable. 



