THE ART OF THE SECOND GROWTH 



the timber quality of the trees left; and quantity thinnings meant 

 to result in the maximum production of wood fibre per acre per 

 annum. 



If left alone, a dense thicket grows but slowly, the food being 

 subdivided among a large number of messmates. Toward the 

 beginning of forestry, sylviculturists were satisfied with "burying 

 the dead and moribund poles." Later on, thinnings were extended 

 into the suppressed classes. The European experiment stations 

 are now deeply engaged in working out the " best " method of 

 thinning. Obviously, no method can be best for all sorts of species 

 and for all sorts of local conditions. 



I. The German and Austrian experiment stations distinguish 

 between : 



Grade 1. Light thinnings, removing the dead or dying. 



Grade 2. Moderate thinnings, removing the dead, dying and 

 suppressed. 



Grade 3. Heavy thinnings, removing also the condominating 

 trees, or such of them which are not absolutely essential for the 

 maintenance of the main leaf canopy overhead. 



Grade 4. Very strong thinnings, placing a limited number of 

 dominating and predominating trees in a free position. 



Results so far published allot the maximum volume production 

 (exclusive of branches) per acre to Grade 3. All these four grades 

 might be characterized as " thinnings from below " (Eclaircies par 

 le bas). 



II. The French sylviculturists are advocating, on the other 

 hand, "thinnings from above" (Eclaircies par le haut). 



The Frenchmen, as a matter of principle, leave alone the sup- 

 pressed lower stems, protecting by them the quality of the soil 

 as well as the clearness of boles Avithin the predestined class. In 

 addition, they relieve the tension, friction and struggle for food 

 amongst the dominators by culling out the worst developed domina- 

 tors, or a percentage of those dominators which stand too close 

 together, and which have, consequently, one-sided crowns. 



The objection to the French method lies in the following points: 



a. Material without increment is left on the ground. 



b. Weaklings and dying trees left increase the dangers threaten- 

 ing the forest. 



c. Greater difficulty in marking trees to be removed. 

 However, where quality increment is at stake, the French 



method seems highly advisable. 



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