FOREST LAND AND TIMBER 



141 



sented as evidence of past trends in the Nation's 

 timber supply: 



Volume Volume 



estimate estimate 



Year (billion bd.-ft.) Year (billion bd.-ft.) 



1895' 2,300 1930' 1,668 



1902 2 2,000 1938 8 1,764 



19053 1,970 19459 1,621 



1908 < 2,500 1945'" 1,601 



1909 5 2,826 1953 1,968 



19206 2,215 



' Fernow, B. E. Facts and Figures Regarding Our Forest 

 Resources Briefly Stated. U. S. Dept. Agr., Div. Forestry 

 Cir. 11, 8 pp. 1896. 



. Economics of Forestry. 520 pp. 1902. New 



York. 



3 Defebaugh, J. E. History of the Lumber Industry of 

 America. 2 v. 1906-07. Chicago. 



* Kellogg, R. S. The Timber Supply of the United States. 

 U. S. Dept. Agr. Forest Serv. Cir. 166, 24 pp., illus. 1909. 



5 U. S. Dept. Commerce and Labor, Bur. Corps. Sum- 

 mary of Report of the Commissioner of Corporations on the 

 Lumber Industry. Pt. I, Standing Timber. 38 pp., illus. 

 1911. 



6 U. S. Forest Serv. Timber Depletion, Lumber Prices, 

 Lumber Exports, and Concentration of Timber Ownership. 

 Ed. 2. Rpt. on Sen. Res. 311, 66th Cong., 2d Sess. 73 pp., 

 illus. (Capper Rpt.) 1920. 



' . A National Plan for American Forestry. Sen. 



Doc. 12, 73rd Cong., 1st Sess. 2 v., 1,677 pp., illus. (Cope- 

 land Rpt.) 1933. 



* Cong. U. S., Joint Committee on Forestry. Forest 

 Lands of the United States. Sen. Doc. 32. 77th Cong., 

 1st Sess. 44 pp., illus. (Joint Congressional Committee 

 Rpt.) 1941. 



9 Woods, J. B. Report of the Forest Resource Appraisal. 

 Amer. Forests 52: 413-28. 1946. 



'" U. S. Dept. Agr. Forest Serv. Forests and National 

 Prosperity. Misc. Pub. 668, 99 pp., illus. 1948. (Re- 

 appraisal Rpt.) 



While trends may seem apparent, all of the 

 published estimates of sawtimber volume actually 

 lack direct comparabilit3\ However, since 1928, 

 when a national forest survey was authorized by 

 Congress, the measurement of timber volume by 

 board-foot and cubic-foot units has been extended 

 to many forest regions. Each subsequent na- 

 tional estimate has been based more and more 

 upon this forest survey. 



The reasons for lack of comparability are many 

 and complex. Briefly, though, they may be sum- 

 marized as follows: As efforts have progressed to 

 measure accm-ately the timber supply, utilization 

 standards have changed, so that the sawtimber 

 and growing stock volumes based on these stand- 

 ards have changed too. For sawtimber trees, the 

 earlier studies used higher diameter limits than 

 the more recent studies. Likewise, the percent of 

 defect permitted in merchantable timber is higher 

 now than formerly, and some species once con- 

 sidered as noncommercial are now included in the 

 commercial group. These and other changes in 

 utilization standards have a most significant bear- 



ing on the comparability of periodic timber volume 

 estimates. 



Another factor has been the changing definition 

 as to what constitutes forest land. Consequently, 

 at times, estimates of the commercial forest area 

 have increased, and at other times they have de- 

 creased, thus changing the estimate of the supply 

 of merchantable timber. Changes in land use as 

 the result of land clearing or abandonment are 

 involved too in determining timber volume. 



Improvement in timber inventory procedures 

 has also been a factor. Use of more accurate base 

 maps, of aerial photographs, and of scientific 

 sampling methods revealed inadequacies of older 

 estimates and the danger of comparing them. 



Finally, the progress of the national Forest 

 Survey since 1930 has been a major factor in re- 

 fining the successive estimates. As each periodic 

 appraisal was made in 1938, 1945, and 1953, the 

 forest area covered by the national survey project 

 has increased. Thus, the published reports 

 inevitably lack comparability. 



Data Adjusted for Comparability 



Taking into account, to the extent possible, the 

 factors noted above, the 1945 data in published 

 reports were adjusted to bring the estimates into 

 accord with 1953 standards. The method of ad- 

 justment varied between States, depending upon 

 the Forest Survey and other data available. The 

 adjustments were admittedly crude for the 30 per- 

 cent of the commercial forest area where Forest 

 Survey data were weakest. Elsewhere it is be- 

 lieved that the Forest Survey provided a reason- 

 ably good basis for adjusting or reconstructing the 

 1945 estimate through providing for major area 

 changes, lowering the diameter limit for sawtim- 

 ber, interpolating between original survey and 

 resurvey data where possible, projecting back- 

 ward 1953 data using growth rates and estimated 

 annual cut, and using what other data subsequent- 

 ly became available. 



Apparent Overall Changes Show 

 No Discernible Trends 



The comparison of adjusted figures for 1945 

 with the 1953 estimates suggest the possibility 

 that the total growing stock volume has increased 

 about 2 percent in the eight-year period, whereas 

 the volume of sawtimber has declined about 2 

 percent (table 87). However, it would be inap- 

 propriate to draw any definite conclusions from 



