THE ART OF THE SECOND GROWTH 



The sectional area of an acre of forest is the sum total of the 

 sectional areas of the trees standing thereon. It rarely exceeds one- 

 lialf per cent, of the acreage of the ground, or 218 square feet per 

 acre. On the Pacific Coast, more than twice this figure is reached 

 by the Douglas Fir. 



E. Rotation. 



By rotation is understood the number of years which a seedling 

 requires to reach maturity. For a second growth in America, 

 rotations will vary in length from 60 years to 160 years, according 

 "to the species and local conditions. During a rotation a wood lot 

 may pass through the cleaning stages, thinning stages, the stage 

 of preparatory cutting, the seed-cutting stage and the stage of final 

 removal. Out of thousands of specimens borne, but a few dozen 

 -persist to the end of the rotation. 



F. Size classes and age classes. 



I. Pinchot adopts the following seven age classes or size classes 

 of trees in his "Primer: " 



a. Seedlings, up to 3 feet high. 



b. Small saplings, from 3 to 10 feet high. 



c. Large saplings, 10 feet high to 4 inches diameter. 



d. Small poles, from 4 inches to 8 inches diameter. 



e. Large poles, from 8 inches to 12 inches diameter. 



f. Standards, from 12 inches to 24 inches diameter. 



g. Veterans, over 24 inches diameter. 



II. During the sapling stage, the specimens form a thicket; 

 •during the pole stage, they form a polewood; and during the 

 standard and veteran stage, a tree forest. 



III. During the thinning stage (pole stages) of trees in an even- 

 aged wood, the following classes of mess-mates might be distin- 

 guished : 



a. After Schlich, " Dominant," " Dominated," " Suppressed, yet 

 alive," and " Dead." 



b. After Pinchot, " Dominant." " Retarded," and " Overtopped." 



c. The usual classification, adopted by German foresters after 

 Krafft is: 



1. Predominating trees, having crown strikingly well developed. 



2. Dominating trees, with well-developed crowns, forming the 

 main cover overhead. 



3. Condominating trees, with crowns of a fairly normal form, 

 l)ut of somewhat poor vigor, carrying, however, their crowns within 

 the level of the main canopy. 



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