52 THE PRINCIPLES OF HANDLING WOODLANDS 



be grouped together in the oldest age-class as trees which 

 have ceased productive growth and ought to be cut. 

 Thus, in northern Idaho this age-class might comprise all 

 the trees over about 150 years of age. It is evident that 

 under these conditions the oldest age-class would far 

 exceed in number of trees any other age-class, and might 

 occupy in the aggregate 50 per cent, or more of the area. 

 The rest of the area would be occupied by trees belong- 

 ing, in more or less varying proportion, to the age-classes 

 below 150 years. In handling a virgin forest this unde- 

 sirable representation of the age-classes cannot be helped. 

 The mature trees should be cut and used, even if their 

 removal disturbs the arrangement of ages. In the sub- 

 sequent treatment of the forest, however, the gradual 

 establishment of the proper proportion between the age- 

 classes is kept in view. 



Very commonly in this country it is necessary to 

 make cuttings before complete working plans have been 

 developed, and it is not possible to determine what 

 system of management will* be best to use in the long 

 run. The first cuttings are therefore made conservatively 

 on the selection system. In some cases without question 

 the second cuttings will be comparatively heavy and will 

 practically be shelter-wood cuttings, which transform the 

 stand in a comparatively short time into an even-aged 

 form. If, on the other hand, at the second cutting it 

 seems desirable to continue the selection system, cuttings 

 are made with a view to bringing about a proper repre- 

 sentation of different ages. 



