224 A NATIONAL PLAN FOB AMERICAN FORESTRY 



to saw timber and therefore reduce the saw-timber growth. The 

 degree to which cutting is made in accordance with good silvicultural 

 practices also has a distinct bearing upon growth. Such practices 

 would tend to increase total yields and at the same time build up the 

 growing stock in the cordwood and younger age classes. 



The factor of greatest weight and uncertainty is that of drain its 

 value, character, location, etc. Although the estimated current an- 

 nual growth for 1950 given in table 19 is in no sense a prediction of 

 what will actually transpire, an effort has been made to select as- 

 sumptions as to drain which might conceivably be realized, taking into 

 account the effect of the present depression, the bearing of limited 

 usable supplies in the eastern forest regions, and the possibilities for 

 constructive forestry measures. For all the eastern regions the drain 

 for the period from 1930 to 1950 was assumed at an average rate 

 equal to one half the 1925-29 drain. Because of the severe depletion 

 of growing stock which has already taken place in these regions a 

 continuation of the 1925-29 drain seems impossible. The current 

 low ebb of lumber production, which is probably less than half the 

 1925-29 rate, probably will be followed by a period of increased 

 production before the exhaustion of suitable saw-timber supplies 

 forces a protracted restriction in the cut, especially in the Lake- 

 Central-South section. Some students of the situation believe that 

 by 1950 the saw-timber drain in the East is likely to be less than 

 half the 1925-29 rate, but an average of one half for the two decades 

 appears to be a reasonable assumption as a basis for this calculation. 

 On the other hand, because of the large reservoir of old-growth 

 stumpage, there seems to be no reason, with favorable economic con- 

 ditions, why the 1925-29 rate of drain in the West as a whole may 

 not be continued until 1950. 



With these assumptions as to drain, forest conditions which might 

 obtain in 1950 were projected. The stands in each region, as of 1930, 

 were reduced at the assumed average rates of drain for the 20-year 

 period. Growth was allowed on all stands until the theoretical time 

 of cutting. An estimate based on the growth rate and age classes 

 was then made of the area and volume of cordwood stands which 

 would reach saw-timber size by 1950, the theoretical amount which 

 might so mature being reduced by the area which would be cut over 

 as cordwood. In a similar manner, the amount of restocking land 

 which would advance to cordwood size was estimated. With the 

 distribution of growth classes and the corresponding volumes of 

 standing timber in 1950 set up in this way, the theoretical current 

 annual growth at that time was calculated by the same method used 

 for present current growth. 



Of special importance is the comparison, shown in table 19, of 

 current growth as of 1950 with current 1930 growth both for saw 

 timber, and for saw timber and cordwood combined, and also with 

 the assumed reduced drains. For the New England and Middle 

 Atlantic regions together the 1950 growth rates of both saw timber, 

 and saw timber and cordwood combined, would increase, and would 

 exceed the assumed average drains. In the Lake-Central-South sec- 

 tion, ^on the other hand, the growth of saw timber alone would 

 remain about as at present and also at less than one half of the 

 assumed average drain. The combined saw timber and cordwood 

 growth, however, would exceed the present growth and also the as- 



