150 



TIMBER RESOURCES FOR AMERICA'S FUTURE 



Table 91. — Trends in net annual growth jor the 

 United States, 19U-52 



GROWING STOCK 



Species group 



1944, 

 as pub- 

 lished ' 



1944, ad- 

 justed 2 



1952 



Appar- 

 ent 

 change, 

 1944-52 



Eastern hardwoods. 

 Eastern softwoods.. 

 Western species 



Billion 



cu. ft. 



5.89 



3. 94 



2. 06 



Billion 



cu. ft. 



5.89 



3. 78 



2. 79 



Billion 



cu. ft. 



7.08 



4. 39 



2. 74 



Percent 



+ 20 



+ 16 



-2 



Total 



11. 89 



12. 46 



14. 21 



+ 14 



SAWTIMBER 



Eastern hardwoods. 

 Eastern softwoods. 

 Western species 



Total 



Billion 

 bd.-ft. 



12. 08 



13. 17 

 5. 81 



Billion 

 bd.-ft. 

 16.53 

 15. 25 

 11. 57 



Billion 

 bd.-ft. 

 19. 12 

 16.97 

 11. 18 



31. 06 



43. 35 



47. 27 



Percent 



+ 16 



+ 11 



-3 



+ 9 



' U. S. Forest Service. Gaging the Timber Resource of 

 the U. S. Rpt. 1 from a Reappraisal of the Forest Situa- 

 tion, 62 pp., illus. 1946. Published figures of gross growth 

 were converted to net growth for purposes of comparison 

 with adjusted 1944 and 1952 estimates by deducting all 

 mortality from fire, insects, disease, and other natural 

 causes. 



2 Adjusted to bring estimates into accord with 1952 

 standards. 



gain in sawtimber. The greater relative increase 

 in growing stock is especially significant because 

 it reflects the spread and improvement of organ- 

 ized protection from fire. 



With respect to western species, the comparison 

 suggests the possibility that the growth of both 

 growing stock and sawtimber has declined slightly. 

 However, definite conclusions in this regard are 

 not justified because the error of estimate might, 

 in all probability, be such as to nullify the signifi- 

 cance of changes as small as 2 or 3 percent. 



Growth should increase in the West to the extent 

 that the old-growth stands are cut and replaced 

 by more vigorous second growth. However, pre- 

 mature cutting of second growth can offset this 

 increase, and this is apparently happening on 

 small, private ownerships in the Pacific Northwest. 

 A major factor tending to hold down growth in the 

 West in 1952 was the severe outbreak of bark 

 beetles in the Northern Rocky Mountain Region. 



Quality of Present Growth Is 

 Declining 



There is little quantitative information on which 

 to appraise the quality of present growth. Gen- 

 erally speaking, if small sawtimber trees make up 



the greatest share of sawtimber volume, the largest 

 share of the growth will likewise occur on small 

 trees. In the East, for example, about 40 percent 

 of the hardwood sawtimber volume and nearly 70 

 percent of the softwood sawtimber volume is in 

 trees of 15 inches and less. It might logically be 

 assumed, therefore, that from 40 to 70 percent of 

 the sawtimber growth of eastern species is on trees 

 too small to yield high-quality logs. To get high- 

 grade logs, it is necessary to delay cutting the 

 well-formed trees until they are 16 to 18 inches in 

 diameter or larger. 



Log grades which provide a measure of stand 

 quality likewise provide an indication of quality 

 growth. About two-thirds of the hardwood saw- 

 timber volume in the East, for example, is in Grade 

 3 or poorer logs. While most of this volume is in 

 small trees that would gain in quality if left to grow 

 to larger sizes, some of it is in larger trees too poor 

 to put on quality growth. Thus, from a quality 

 standpoint, whatever growth is added to this share 

 of the volume is largely ineffective. 



On the whole, about one-third of the growth of 

 eastern hardwoods is believed to be in high-quality 

 logs. However, in Indiana, Kentucky, and Ohio, 

 it has been found that the percentage of net 

 sawtimber growth in high-quality logs ranges from 

 14 to not more than 20 percent. In the Lake 

 States, between 1936 and 1953, the total volume 

 of hardwood sawtimber in Grade 1 logs declined 

 40 percent. Decreases ranged from 60 to more 

 than 80 percent for such hardwoods as sugar 

 maple, yellow birch, beech, and soft maple, which 

 more than compensated for the increases in other 

 species, notably basswood 6 percent, oak 25 per- 

 cent, and aspen nearly 200 percent. 



There is evidence from successive surveys that 

 less desirable species are tending to displace pre- 

 ferred species in both the East and the West. 

 Growth that is accumulating on inferior growing 

 stock of both desirable and inferior species is of 

 poor quality. Among the oaks, for example, 

 which contribute three-eighths of eastern hard- 

 wood growth, it is estimated that 55 percent of 

 the growth is attributable to the less desirable 

 species. 



Despite progress in technology to overcome poor 

 quality, it still takes good wood, with relatively 

 few exceptions, to make the kinds of wood and 

 wood-fiber products needed in our expanding 

 economy. Although the cut is mainly from the 

 larger and better trees, successively smaller trees 

 are being cut more and more, thus limiting future 

 prospects for good-quality wood. Growth, on the 

 other hand, is more uniformly distributed among 

 trees of all sizes. 



In summation, the quality of timber growth, 

 like the quality of timber, is declining. The trend 

 will need to be reversed if quality is not to become 

 an increasing problem during the next several 

 decades. 



