FRENCH FIR MANAGEMENT IN THE VOSGES 547 



CARE OF STANDS NOT NORMALLY CONSTITUTED 



If the forest is not normally stocked, we must reduce or increase the 

 figure of the yield, so as to arrive at a normal type within a longer or 

 shorter time, and one will recruit the principal yield in the diameter 

 classes with excess numbers (or z'ice versa), having always as a main 

 guide the normal stem spacing. The most practical method of taking 

 in at a glance the diameter classes of trees that are in excess or deficit 

 is to draw on one sheet with black ink the number of trees existing and 

 with red ink that of the trees that should be there. This can be done 

 for all compartments and for the whole forest on cross-section paper 

 and should be consulted in marking. It can happen — in fact, often hap- 

 pens — that the inventory of a compartment shows the poverty of some 

 diameter classes and consequently the necessity of only cutting dead 

 or dying trees in this class. If, on the other hand, the trees of these 

 diameters, instead of being evenly distributed, are missed on any one 

 point, they should be cut according to the spacing formula. 



SUSTAINED YIELD MARKING ROTATION 



In general, private owners do not search after a regular annual sus- 

 tained yield. . . . If in doubt whether to cut one tree or another, a 

 glance at the two curves, one in red ink representing the normal condi- 

 tion, the other in black ink showing the actual stand, will suffice. 



After the felling is marked, it can be plotted, and it will generally be 

 a surprise to see that the wood of all diameter classes has been removed 

 in about the proportion desired. If the figure of the yield is approxi- 

 mately attained, one can stop there; but if a good deal remains, one 

 will pass to the next compartment until the fixed amount has been ob- 

 tained. In this case the yield will be sustained as to volume and one 

 will sacrifice the prescription of running over the forest in a given time. 



If, on the other hand, it is desired to make a rule of returning peri- 

 odically over the same area at intervals fixed in advance, it will be 

 necessary to sacrifice the sustained yield. One will then determine the 

 length of the cutting cycle and establish such a regulation of cutting 

 that the entire forest may be "run over" during this cycle. In this 

 regulation . . . one may indicate the probable amount to take out 

 in each compartment. 



Cutting Cycles. — The cutting cycle in theory should be very short, 

 five or six years, so as to be able to approximately recruit the amount 

 of the cut without o])t'ning up the stand too much without producing 



