be divided into three groups: Young stands, varying in age 

 from 20 to 40 years. Middle aged stands, from 40 to 80 years 

 old. Old or mature stands, 80 years old or over. 



YOUNG STANDS, 20 TO 40 YEARS OF AGE. 



In young stands the trees are usually too much crowded 

 for thrifty development. There are too many trees to the acre, 

 and many of the trees of the better species are being choked 

 and suppressed by the quicker growing but less valuable ones. 

 In this case thinnings, or improvement cuttings as they are more 

 properly called, are beneficial to the growth of the trees that are 

 left in the stand. They are advisable, from a financial stand- 

 point, only when the material taken out in the cuttings is large 

 enough to be utilized in some way. In the improvement cutting, 

 all trees that are dead, all that are hopelessly suppressed, and all 

 those of inferior species that are interfering with the develop- 

 ment of the better trees should be removed. The chief purpose 

 of all thinnings of this kind is not to produce merchantable ma- 

 terial, but to improve the growth and development of the re- 

 maining trees. 



By the removal of certain trees, the remainder have a chance 

 to expand their crowns and also have the benefit of all of the 

 available nourishment that is in the soil, and are therefore able 

 to make faster growth than if they were crowded and hampered 

 by their undesirable neighbors. For this reason, thinnings of 

 this sort shorten the time needed to grow the trees to a desired 

 size. They may, therefore, prove to be a good and far sighted 

 policy even in cases where the miaterial removed is not valuable 

 enough to pay for the operation at the present time. 



MIDDLE AGED STANDS, 40 TO 80 YEARS OLD. 



Later on in the life of the stand after the improvement 

 cuttings have been made or the natural law of the survival of the 

 fittest has been allowed to run its slow course, slightly heavier 

 thinnings are made in order to provide additional growing space 

 for the remaining trees. 



In this thinning all dead and down trees, all crooked, sup- 

 pressed, dying or badly injured trees should be removed. This 

 opening up of the stand to more light and growing-space will 

 greatly accelerate the diameter growth of the remaining trees. 



