REGULATION OP CUT 231 



be temporary where it is clearly recognized that the rotation adopted 

 is a temporary expedient (see p. 191). 



The Normal Forest. — The normal forest with its normal distribution 

 of age classes, normal increment, and normal growing stock is not used 

 by the French Government in its regulation. Where the normal forest 

 is used in working plans it is the empirically normal stand based on 

 selected average local stand tables which show the volume in cubic 

 meters and the number of trees by age classes. Schaeffer, in his de- 

 velopment of working plans for selection fir stands in Savoie and Haute- 

 Savoie, used this empirical normal stand as a basis of comparison, 

 especially for marking the fellings prescribed by the working plan (see 

 p. 256). 



Regulation of Cut. — The regulation of the cut comprises two dis- 

 tinct operations: (1) The final fellings, regulated by area or volume or 

 both, which naturally constitute the chief return. These are regulated 

 by the working plan in general terms while much depends on the progress 

 of regulation and accidents: "A more complete regulation is necessary 

 for administration; year by year there must be prescribed the place, 

 the kind, and the quantity of the felhngs to make." (2) Intermediate 

 fellings or thinnings, which are not regulated by volume but by area. 

 This form of regulation is also applied to the cork-oak bark collections 

 and to the resin crops from maritime pine. 



The essential regulation of French public forests may be classified as 

 follows : '1 



example, in a slow growing forest, like Risoul, the rotation is 180 years, while in La 

 Grande C6te, where the growth is much better, the rotation is reduced 30 years to 150 

 years. In the forest of La Joux, notwithstanding the rapid growth, the rotation is 150 

 years, because in this State forest very large wood was desired (Bois de Marines). 

 The low returns from long technical rotations may be somewhat increased by the 

 higher prices secured from large-sized timber. 



'1 Masson's method, like Von Mantel's, which consists in dividing the total growing 

 stock of the forest by half the length of the rotation, is well known. In applying this 

 method there is realized each year a fraction of the stand represented by 2/R. This per 

 cent of realization is not a function of the rotation. It will be 2 per cent for a rotation 

 of 100 years, 1.43 per cent for 140 years, 1.12 per cent for 180 years, and 1 per cent for 

 200 years. It is necessary to have a normal stand or the cut is too high for an im- 

 poverished forest and too low for a rich, well-stocked forest. In order to obviate this 

 error Schaeffer worked out a correction figure based on a knowledge of the stand per acre. 

 (No. 3, 1905, B. de S. F. de F. — C. et B.) 



The Masson formula was used extensively in the Vosges in the middle of the last 

 century and gave fairly accurate results, simply because the fir rotation was usually 

 140 years, and by the formula the yield was thus 1.4 per cent which happened to agree 

 exactly with the average site of the Baden yield tables for silver fir. This method is 

 no longer in use (see Appendix K (2)), because the fundamental assumptions, on 

 which the formula is based, are in error. 



