SYLVICULTURE 



withdraw every ten years the largest one-seventh of the stems 

 containing about one-quarter of the total volume. 



Of course, high and early revenue is seetu-ed by such practice. 

 On the other hand, the trees removed are those growing at the 

 best, rate of interest. (From the sixtieth year on 90% of annual 

 secretion in a woodlot is supplied by the 407o (in number) of the 

 largest trees). 



The advisability of a Borggreve thinning largely depends on 

 the reproductive power of a, wood thus " maltreated." In the case 

 of Yellow Pine and on poor soil, the reproductive power of a wood 

 seems too small to allow of speedy repletion of the growing stock 

 and of its leaf canopy. Much " food " goes to waste after Borg- 

 greve thinnings. In the case of White Pine and Spruce, the danger 

 from storm and sleet after Borggreve tninnings must be badly 

 dreaded. 



IV. Wagener, at the year twenty-five of a forest, makes u, 

 thinning called " erown-free-cutting," surrounding the crown of 

 each predestined tree with an air space two and one-half feet wide. 

 Dominating trees left should stand seven yards apart after the 

 Wagener thinning. Suppressed trees are not interfered with. Such 

 cuttings are much heavier than Borggreve's. At the year twenty- 

 five the bole of tlie dominators is not fully developed. Underplanting 

 takes places at the same time. The dominators left stand in an 

 orchard-like position and show a very rapid diameter growth. Only 

 one log or so is expected to be obtained from the bole; it is obtained, 

 however, within an extremely short rotation. 



Obviously, for coniferous woods exposed to storm and of poor 

 quality if wide ringed, the Wagener system is out of the question. 

 The Wagener thinnings, unless' they result in a heavy growth of 

 adventitious branches, might be used to advantage for Black Wal- 

 nut, Black Cherry and Oaks. 



V. In mixed forests such species as reach maturity during the 

 pole stage might be removed by way of thinnings; f. i.. Locust and 

 Sassafras from a pole wood of Yellow Poplar; Hickory when reach- 

 ing spoke-bolt size from a mixture with Oaks; Chestnut when reach- 

 ing telephone pole size from a mixture with Oaks, Black Gum and 

 Yellow Poplar. 



^ 

 Paragraph LXIII. Pruning in high forest. 



A. The object at stake might be: 



I. Production of logs free from knots,— especially free from 

 dead knots. Live or sound knots measuring one and one-quarter 



133 



