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GOVERNMENT REGULATION AND WORKING PLANS 



which could easily be corrected, tends to make the growth per cent 

 appear too high. (3) The method as originally designed requires fre- 

 quent and accurate stocktaking and therefore is expensive and tedious. 

 (4) The accuracy of the growth calculations depends on accurate 

 inventories which might easily be in error by 5 to 10 per cent. There- 

 fore if both the (a) first and (6) second inventories were (a) 10 per 

 cent too much and (6) 10 per cent too little an error of 20 per cent 

 would result in the yield. (5) Too much is left to the opinion and judg- 

 ment of the forester. (6) Huff el advances another objection with which 

 the writer is not wholly in sympathy, namely, that it is dangerous to 

 examine too minutely the growth of trees of different sizes and ages 

 because the stand should be regarded as a whole. The tendency to-day 

 in the opinion of the writer is to use more judgment in treating selection 

 stands and if possible to get rid of tree classes which show they are 

 declining in vigor or annual growth. On the other hand the method 

 would not work well with abnormal stands. 



Illustration. — Suppose a selection fir forest of 1,000 acres were 

 divided into ten equal cutting areas, and that every 10 years, beginning 

 in 1910, all trees over 12 inches in diameter were calipered and estimated 

 by 2-inch diameter classes. Gurnaud would first calculate the growth 

 for each cutting area as follows: 



To arrive at the true growth a deduction must be made for the 140 



trees which grew into the merchantable size class: 140, 11-inch trees X 100 



board feet, or 14,000 feet board measure; true growth for 10 years, 



56,000 feet board measure; true growth for 1 year, 5,600 board feet. 



5,600 



980,000 



= .57-|- per cent or better if the mean of the two inventories 

 5,600 



were to be taken 1,000,000 -|- 980,000 = .56 -f per cent. The stand 



2 

 per acre would be 10,000 feet and the growth per acre per year 56 

 board feet. When it comes to an analysis of the stand separately for 

 each size class the process is somewhat more complicated; those inter- 

 ested in a further study of the method should study La M^thode du 



