AVERAGE WOOD PRODUCTION IN THE UNITED 



STATES. 



On pages 304-5 of the Forestry Quarterly for August, the 

 reviewer of Forest Service Circular 166, "The Timber Supply of 

 the United States," after quoting some of the statistics given in 

 the Circular, continues : 



"The author also attempts to prognosticate future supplies. It would 

 have been interesting to know how he came to the assumption that the 

 annual growth 'does not exceed twelve cubic feet per acre, a total of less 

 that seven billion cubic feet.' He properly makes the assumption that 

 three conditions exist ; namely, mature forest ; partially cut and burned 

 forest; and severely culled forest, 'on which there is not sufficient young 

 growth to produce another crop of much value.' He estimates these con- 

 ditions — of course, also mere guesses — to be represented by 200, 250 and 

 100 million acres, respectively. But, instead of using these figures in a cal- 

 culation, he jumps to the above conclusion as to new growth. Of course, to 

 arrive at such or any conclusion in this regard, some more assumptions are 

 necessary. The matter is of such a speculative character, that, unless the 

 full basis for it is stated, it becomes worse than useless, and, used as an 

 argument as if it were true, dangerous. We believe it untrue." 



Then follows a discussion leading apparently to the conclusion 

 that the average increment per year for all our forest area during 

 the next 60 years might be about 8 or 9 cubic feet per acre, an 

 estimate which tallies closely with that given on page 51 of 

 "Economics of Forestry," and which upon the assumptions given, 

 is very reasonable, although the author says, it is probably far 

 too high. I wish, however, to call the reviewer's attention to the 

 fact that the conclusion reached in the circular — that the annual 

 growth for all our forest area does not exceed 12 cubic feet per 

 acre — is not a mere jump as he implies, but is the result of a 

 carefully worked out calculation in which the different classes of 

 forest land in each region were considered. Circular 166 is but 

 a brief popular statement of the best facts and estimates which 

 our present knowledge enables us to give concerning our forest 

 resources. It states only conclusions. Space, and its non-technical 

 character, forbade filling the circular with the details of forest 

 calculations. The data upon the growth and yield given in 

 the Circular are based upon the very excellent paper entitled 

 "Rate of Forest Growth," prepared by Mr. E. A. Ziegler for the 

 National Conservation Commission, and published in Vol. II of 



