AEEA (VOLUME) ALLOTMENT BY PERIODS 239 



enriched poor stands and in some cases has resulted in an excessive 

 growing stock. But the excess of the timber capital is in accordance 

 with the government policy of conservation. From the viewpoint of 

 good silviculture, Schaeffer has formulated a rule for selection fir-spruce 

 stands of always cutting at least two-thirds the actual increment each 

 year. Otherwise the stand cannot be maintained in good condition 

 because if less than two-thirds the increment is removed it means that 

 some diseased or decrepit trees must be held over a cutting cycle. Such 

 a rule has wide application to similar stands in the United States when 

 a wave of forest saving shall finally lead us away from the current forest 

 destruction. To practice too intensive economy in a stand means an 

 increase in defective timber. 



Area (Volume) Allotment by Periods. — This method, called by French 

 writers the ^ "combined method," is as follows when applied to an 

 (see i page 232) even aged high forest : The method is applied throughout 

 France to the rich oak-beech high forests which are so noteworthy in 

 the so-called Parisian zone of the Plains (see p. 30) where the regenera- 

 tion is by the shelterwood system over a regeneration period of 20 to 

 30 years. Formerly great stress was laid on the necessity for an orderly 

 sequence of fellings. Lately the tendency is to break away from any 

 preconceived order of felling and instead to base the order and sequence 

 of fellings on the conditions actually existing in the various compart- 

 ments.'* But protection against dangerous winds and the maintenance 

 of protection belts of old timber is always sought after. In the spruce- 

 fir forests great difficulty has been experienced in regularizing fellings 

 (see p. 75). 



"After having fixed the length of the rotation, it is divided into equal periods, which 

 should be long enough to permit the regeneration of a complete forest canton (during 

 a period) ." 



The period adopted is usually 20 to 30 years and rarely 40 years. 

 The next step is to determine what compartments are to be cut during 

 each period. 



^ See Huflfel, Vol. Ill, "M6thode combinte.'' To give an accurate picture of how 

 the French apply this method, the text has been followed as closely as possible. 



" Where the shelterwood system was applied to fir-spruce stands it had been cus- 

 tomary to divide the forests into four fixed periodic blocks corresponding to four periods, 

 equal to one-fourth the rotation. This led, according to Huffel, to "excessive cutting 

 of large timber on half the area (blocks I, IV, and sometimes III), absolutely deplor- 

 able felling of average-sized timber on most of the forest (blocks I, IV, and often II), 

 and during (the operations) the maintenance of overmature timber in the second 

 periodic block no less deplorable. ... In the first period the revenue was too 

 much, in the second about correct, in the third a deficiency, and in the fourth very 

 deficient. . . . The "pr6comtages" invented in the last case to correct this de- 

 ficiency rendered the yield calculation incoherent and illogical, without remedying the 

 evil very much." 



