164 THE PRINCIPLES OF HANDLING WOODLANDS 



particularly valuable in filling gaps, especially after the 

 final cutting. 



The width of the strips varies with conditions, and 

 depends chiefly on the danger from windfall. The greater 

 this danger is, the narrower must be the strips. They 

 usually range in width from 100 to 600 feet. The period 

 of reproduction with a given stand is the same as in the 

 uniform system, namely, from 20 to 30 years, usually the 

 former. If a stand is so long that a series will not be 

 complete within the assigned period of reproduction, 

 two or more cutting series are made in the same man- 

 ner as described on page 133. The result is an approxi- 

 mately even-aged stand, with the trees at the side where 

 cutting began somewhat older than at the other side. 

 The difference in age would be hardly noticeable when 

 the stand reaches maturity. 



Shelterwood Cuttings in Groups 



This is a further modification of the principles of the 

 shelterwood system, by which the cuttings are concen- 

 trated at special points in the stand, and reproduction is 

 secured in groups, instead of in strips. 



The svstem is used in mountain forests where breaks 

 have occurred and groups of advance growth have been 

 established. These groups are used as centers of repro- 

 duction. The cuttings begin about them and progress 

 radially from them. Ultimately, all groups are merged 

 together. 



To illustrate concretely, suppose that in a given ma- 



