CHAP, ix.] Tending of Woods 187 



tinguished sylviculturist of Thuringia, who was for many years 

 the Principal of the Forest School at Eisenach, wrote as 

 follows * : 



' Granted that the thinnings begin at the proper time in the case of 

 the Beech about the twenty-fifth to thirty-fifth year, the Spruce about the 

 twentieth to thirtieth year, and the Scots Pine about the fifteenth to 

 twenty-fifth year that they are regularly conducted, that the yield 

 therefrom is not reduced by any peculiar local circumstances (such as 

 right of collection of windfall, or interruption of density in canopy due to 

 snow accumulations, &c.), it may be expected that on the average the 

 proportion which the intermediate yield from thinnings bears to the final 

 yield of the mature crop will be : 



In Beech Woods, with a rotation of 



80 years, from 12-20 per cent. 



100 i4- 2 5 

 120 16-30 



The lower percentage is obtainable from poor soils, the higher from 

 the better classes of soil. 



In Spruce Woods, with a rotation of 



60 years, from 15-17 per cent. 



80 20-22 



ioo 23-26 

 The higher percentages are obtainable from the inferior classes of soil. 



In Scots Pine Woods, with a rotation of 



60 years, from 1 8-24 per cent. 

 80 22-28 

 ioo about 25 

 The higher percentages are obtainable from the inferior classes of soil.' 



For pure Spruce forests on the Harz Mountains, Theodor 



Hartig found the following total number of stems per acre 2 : 



At 20 years of age, 9,2653 of which 49 



40 1,249 42 



60 603 32 



80 388 21 



>, ioo 282 ii 



I2 238 4 



1 Die Bctriebs- und Ertragsregelung der Forste, 1879, p. 300. 



2 Gayer, Waldbau, 3rd edit. 1889, p. 15. 



3 This only refers to natural reproduction and sowing ; it would of course 

 be much less in the case of plantations. But compare with the above the 

 remarks made on page 57. 



might be advantage- 

 ously removed by 

 thinning. 



