158 Forestry Quarterly 



(age, condition) Vv^ill modify the growth and change this from a 

 normal to an abnormal growth. This change may be and usually 

 is in two directions: a change in volume, and a change in quality 

 (age, size, etc.)- 



If the rotation, for instance, is 100 years and the growing 

 stock, instead of being made up evenly of all age classes, is changed 

 to one in which older timber (80 to 100 years) predominates, 

 the growth in volume will be less than normal; if the 30-60 year 

 old stands predominate it may be larger than normal. But if 

 30-60 year old stands predominate it is evident that the cut must 

 get along v/ith smaller material, etc., and the quality suffer. 



Normal growth, and after all it is growth that is wanted in 

 growing a timber crop, depends on the normal growing stock, and 

 any serious reduction or modification changes the normal growth 

 to an abnormal and therefore less desirable one. 



But while these conditions are quite a,pparent and easily under- 

 stood in the case of a forest made up of even-aged stands, they 

 are much less evident or apparent in the case of the selection 

 forest of all-aged or many-aged stands. In the textbooks, too, 

 this form of forest is not treated fully, and for obvious reasons. 

 With less than 2 per cent of the State forests in selection forest, 

 the importance in Germany of this form is certainl}'' small. But 

 in our large mountain forests and millions of acres of other wild 

 woods, the selection method is likely to have importance for a 

 long time to come. For this reason a few words here may be 

 justified. 



Generally, the condition of age classes, the growing stock in 

 volmne and character, the relations of growth and cut are apt 

 to be misunderstood, and if the following looks like the ^^ery ABC, 

 it is certainly not so to the majority of beginners. 



To understand a selection forest it is again necessary to assume 

 a model, a perfectly regulated forest, such as might be developed 

 by a century of careful cutting. It is also necessary to assume 

 that the site is uniform, that we deal Vvdth a single species, and 

 finally that the silviculture is good, i. e., that the period of return 

 is not too long and that the cut is made w4th an eye to good 

 reproduction and gro^^'i:h. The reproduction, say in good South 

 Michigan hardwoods, would come in easily during the first five 

 years and all later comers v;ould fail for lack of light and room. 



