Periodical Literature 549 



dominant of the polewood stage ; the fact of a considerable incre- 

 ment increase in younger and middle classes due to severe open- 

 ing up ; most favorable density at time of planting not less than 

 4,000 plants (for spruce, which lacks in spreading habit, 60 per 

 cent of this number is ample). The pine is a species with especial 

 crowding habit and a rapid grower in its youth, hence a relatively 

 dense position in the first stage is the surest method of securing 

 a sufficient number of satisfactory shafts ; but the axe must begin 

 early, in 20 to 35 years, to select the final harvest crop, open up 

 the groups, and free the trees of the future to secure well formed 

 crowns; that is to say, early thinning in the dominant is indi- 

 cated which with age changes quite naturally into the form of a 

 severe thinning in the subdominant which should begin in the 

 35th year. The selection of the eventual harvest crop is easy 

 if there is a sufficient number to choose from. In the final har- 

 vest stand the pine will then have, say, 120 trees, while the spruce 

 which started with 60 per cent of the number of pines will show 

 200. While at the beginning the spreading habit was the deter- 

 minant of numbers, at the end the light requirements of the 

 species rule. 



The author doubts the correctness of Schwappach's negative 

 result of the difference in the degree of thinning on the produc- 

 tion ; the result of the measurements being vitiated by the lack 

 of stands that had been properly treated at the start. If only 

 stands so treated are selected from Schwappach's material a con- 

 siderable absolute increment in younger and middle classes is 

 noted. 



The author then cites at length Kunze's celebrated thinning 

 areas, worked for 50 years (see F. Q., XII, p. 273), to support 

 this expectation most convincingly. This stand showed that light, 

 moderate and severe thinning in pine produced timberwood at 

 70 years of 6,150, 6,265 and 7,000 cubic feet respectively. 



Among other interesting results, this example shows also that 

 the length of the crown varies with these three degrees of thin- 

 ning, the severe thinning producing the longest crowns ; never- 

 theless, since this thinning also produces the greatest height, the 

 clear length is after all longer: the severe thinning does not 

 produce shorter or less clear material. 



