544 



JOURNAL Olf FORESTRY 



The two series of tests having given approximately the same results, 

 the ratio 15 has been adopted. With this average ratio of 15, one can 

 keep the young stands sufficiently dense, the young trees grow suffi- 

 ciently in the bole, while the mature trees have a sufficient area to de- 

 velop their crowns, important in respect to their individual rate of 

 growth. This ratio gives the criterion for good cultural operations; 

 not to have the young trees too dense, . . . but dense enough to 

 prune the bole ; thus two trees 20 cm. in diameter must be spaced 20 

 cm. X 15, or 3 meters ; 2 trees 40 cm., 40 cm. X 15. or 6 meters ; a tree 



25 cm. and a tree 45 cm ^^ ^ ^^ X 15 = 5-25 meters.^ It is now 



easy to determine the surface occupied by the tree of each diameter 

 class and to deduct the number which must be removed per hectare. 

 The results obtained are figured in the table which follows, as well as 

 the volumes, basal areas, and price. This table gives the normal con- 

 dition after the felling : 



Table 2. — Normal Condition at the Beginning of the Cutting Cycle 



* M. Algan (E. & F., XXXV, 1896, p. 162) gives as a result of his experiments: 

 D = iod + i'«. where D is the distance between the two trees; d the d. b. h. of 

 these trees. This formula gives the same results as our S for trees 20 cm. in 

 diameter but less for larger trees and more for smaller trees. 



D. B. H. D = iod4-i D==i5d 



15 cm. 1,600 trees with 216 cu. m., 1,976 trees with 207 cu. m., worth 



'worth 1,944 frs- 2,403 frs. 



60 cm 204 trees with 735 cu. m., in trees with 400 cu. m., worth 



worth 13,230 frs. 7,200 frs. 



