CHAP, x.] Stimulation of Increment 227 



good individual crowns. By this means, in place of having 

 a pure forest formed, according to Weise's Yield-Tables \ on 

 soil of average quality at eighty years of age by 317 stems 

 per acre (having a mean average girth of 29 inches at breast- 

 height, which would only be attained by about 40% or 127 

 stems, with a form factor of 0-45 and a current annual 

 increment of only 44 cubic ft. per acre), it can hardly be 

 doubted that a smaller number of trees with enhanced incre- 

 ment and the finer dimensions of stem effected by the com- 

 paratively rapid thickening of the bole at the top end must 

 yield more favourable financial returns on the capital invested 

 in timber production. Reliable comparative data are, how- 

 ever, unfortunately not yet available to illustrate this point. 



Larch. In regard to general treatment by partial clearance 

 with a view to the speedy production of large-girthed timber, 

 the Larch has much in common with the Oak ; but the under- 

 planting may sometimes take place more advantageously with 

 the Silver Fir than the Beech. So far as experience goes, this 

 method of treatment is well adapted to the cultivation of the 

 Larch on good, deep soil ; and it is most satisfactory when the 

 partial clearance and underplanting takes place as early as the 

 twenty-fifth to thirtieth year. When the previous tending of 

 the plantations has been good, and the thinnings have been 

 regularly made, the main partial clearance can be heavier than 

 in the case of the Oak, so that subsequent clearances are often 

 almost unnecessary. On good soil from sixty to seventy trees 

 per acre may remain to form the final yield of the standard 

 crop ; and wherever soil and situation are at all suitable for the 

 growth of Larch, sixty- or seventy-year-old crops can often yield 

 an increment of 3 to 4 % up to that age, when they should 

 already show very good marketable dimensions. 



As the Beech is not in favour or demand as a timber-tree of 

 large dimensions, this method is only apt to find any practical 



' l Yield-Tables for the Scotch Pine, translated by W. Schlich, Ph.D., 

 1888, pp. 18, 19. 



Q 2 



