110 NATURAL REGENERATION 



"At 15 years there is a second thinning (made with an axe), this coupled with a 

 pruning of the remaining trees up to the maximum height the face wUl reach, that is to 

 say up to 6.6 to 9.8 feet above the ground. At 20 years there is a third thinning, pre- 

 ceded by the tapping of the trees destined to be felled. There is no reason to try to 

 maintain the vigor of these trees; the essential is to realize as quickly as possible all the 

 resin which they can yield; they are . . . tapped to death at 25 years, and at 30 

 years there is a fourth and a fifth thinning, always preceded by tapping to death. After 

 the fifth thinning is cut out the stand becomes very open; it is hardly complete. This 

 condition is, however, favorable to the growth of maritime pine, since the crown, when 

 well thinned or in full sunhght, produces more rapidly the substances necessary for the 

 formation of wood and resin. The pine trees which remain are now called pins de place 

 and are tapped alive, that is to say they are worked with a moderate number of faces so 

 as to obtain a reasonable amount of resin without compromising the vitality of the tree. 

 This tapping will be continued, moreover, during the entire hfe of the tree (with 1 or 2 

 years of respite). In addition the thinnings (every 5 years) are continued in the stand 

 until the time comes for regeneration by clear cutting; it should be imderstood that each 

 thinning is preceded by the tapping to death of the trees marked for feUing." 



In Scotch pine it is often dangerous to wait until trees are large enough 

 to yield mine props; it is better to start thinnings earher, say at 18 or 

 20 years, as purely cultural operations. After once starting they should 

 be made every 7 to 8 years [163]. In mixed stands [182], such as beech 

 and fir, the thinnings should favor the fir against the beech, since the 

 latter is essentially adapted to an understory rather than to the major 

 stand [182]. In even-aged stands it is the French practice to choose 

 the trees which should form the future stand and then favor them in 

 the thinnings. The mere removal of suppressed or intermediate trees is 

 not countenanced, since the French beheve very firmly in thinning the 

 upper story [200]. The chief aim in making thinnings in the coppice 

 of a coppice-under-standards stand 8 to 10 years before the coppice is 

 cut is to increase the diameter growth of the most vigorous trees which 

 will make the best standards for the upper story during the succeeding 

 rotations [245]. 



Another operation, in reahty a thinning or loosening (depressage) 

 in seedhng stands, is very necessary in crowded maritime pine regenera- 

 tion, and often in dense clumps of Scotch pine reproduction, to prevent 

 damage by fungus through overcrowding. Jolyet -^ says of it : 



the cost of logging. Huff el says in the preface to Vol. II of Economie Forestiere: 

 "Exaggerated thinnings are fatal to the health and finally to the very existence of forests. 

 By breaking the cover and uncovering the soil, they diminish or destroy its productive- 

 ness. The humus disappears; the soil dries out, packs and hardens. The forest is 

 invaded by weeds, heather, and grass; the valuable species are gradually ehminated. 

 If made too suddenly thinnings cause windfall. Too heavy thinnings are imeconomic 

 since they increase the volume of branches and sapwood, yield short tapering boles. 

 . . . They also decrease the quality of wood. . . ." 



27 Influence des Eclaircies dans les Peuplements reguUers de Sapin. E. Cuif, 

 1905. 



