328 



Forestry Quarterly. 



AVERAGE ANNUAL PRODUCTION PER ACRE— 1856 to 1904*. 



This increase in the production of oak under the method of 

 thinning from above is also shown strikingly by comparing the 

 total volume of oak per acre in 1887 and in 1903, as follows : 



Average Valume in Feet Board Measure, Per Acre. 



1887 1903 



I. Thinnings from below, 2,788 feet b.m- 9,214 feet b.m. 

 11. Thinnings from above. 3,043 feet b.m. 10,336 feet b.m. 

 III. Untouched. 2,856 feet b.m. 7,055 feet b.m. 



Under such favoring treatment the growth is sufficiently rapid 

 so that the average rotation does not exceed 200 years. How- 

 ever, no attempt is made to adhere to a fixed rotation or to a 

 fixed annual cut; rather everything is made subservient to the 

 silvicultural exigencies of the species involved. 



The growth of an average oak is somewhat as follows : 



Diameter, breast heiglit, inches- Age, years 



3-94 16 



5-91 34 



7-^7 47 



9.84 60 



* Obtained through the courtesy of M. Cuif, Inspecteur des Eaux_ et 

 Forets, attache a la Station de recherches de I'Ecole des Eaux et Forets, 

 Nancy. 



