SYLVICULTURE 



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

 subdivided among a large number oi messmates. Toward the begin- 

 ning of forestry, sylviculturists were satisfied with thinnings bury- 

 ing the dead and moribund trees. Later on, thinnings were extended 

 into the suppressed classes. The Luropean experiment stations are 

 now deeply engagea 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 experiment stations distinguish between : 

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

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

 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 limitea 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). 



French silvieulturists are advocating, on the other hand, "thin- 

 nings 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 within 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 threat- 

 ening the forest. 



c. Greater difficulty in marking trees to be removed. 

 However, where quality increment is at stake, the French 



method seems highly advisable. 



III. Radically different from the systems of thinnings hereto- 

 fore prevailing are the revolutionary views proffered by Borggreve, 

 the "Bryan" amongst European sylviculturists. 



Borggreve thinnings interfere or remove only the predominators 

 and dominators— the biggest poles-closest to the best log size. 

 Such thinnings begin only at the year sixty of a woodlot; they 



132 



