TIMBER SUPPLY OUTLOOK 



Leonard I. Barrett 

 S. Blair Hutchison 



INTRODUCTION 



Major objectives of forest policy in the United 

 States are to currently grow sufficient timber to 

 meet national requirements and to build up timber 

 resources so that expected rising demands can be 

 sustained. Only by reaching these objectives can 

 the timber capital or inventory remain in condi- 

 tion to supply requirements permanently. 



Preceding sections of this report have presented 

 the current situation with respect to inventory, 

 growth and utilization of timber supplies, protec- 

 tion, planting, productivity of recently cut lands, 

 ownership, and the relation of domestic to foreign 

 resources. Projected timber demands or require- 

 ments for the years 1975 and 2000 have also been 

 estimated. This section presents projections of 

 timber supply and, for the first time in this report, 

 compares projections of both supply and potential 

 demand. The comparisons constitute, in broad 

 perspective, the outlook for the timber situation 

 during the rest of this century. 



The outlook period, extending to 2000, is longer 

 than periods commonly used in projecting needs 

 and supplies of most resources. The reason is 

 that standing timber is a long-term crop and sup- 

 plies cannot be readily adjusted annually. Many 

 of the most fundamental actions affecting supplies 

 have no practical effect for several decades. For 

 example, the improvements in some aspects of 

 inventory and growth since 1945, shown in the 

 sections Forest Land and Timber and Growth and 

 Utilization, are more the result of forestry efforts 

 made 30 to 40 years ago than of those made after 

 1945. Thus, the outlook period used in projecting 

 timber supplies must be long enough to include the 

 effects of actions requiring several decades for 

 concrete results. 



Two broad methods for long-range projections 

 of net growth and inventory were considered 

 during planning stages. One method involved 

 calculation for selected future years of the positive 

 or negative effects on net growth and inventory 

 that could be expected from each type of action 

 or effort affecting supplies, and the subtraction 



from, or addition to, the 1952 base of each effect. 

 Thus, the separate effects of expected trends in 

 protection, planting, improved silvicultural prac- 

 tices, timber cut, and other factors would be 

 determined individually by a "bookkeeping" 

 procediu-e. 



The "bookkeepmg" procedure was cumber- 

 some, and limitations in knowledge prohibited its 

 use for some important species groups in some 

 regions. Since it could not be adopted as a 

 standard method, formulae were finally chosen as 

 the more suitable approach. Formulae were 

 used to measure the changing growth and inven- 

 tory for future periods by projecting values for 

 the factors affecting change. These factors were 

 timber removal, gross growth (net growth plus 

 mortality), and mortality and ingrowth (the net 

 volume of trees that reach minimum measured 

 size in a given period). 



Gross growth, mortality, ingrowth, and timber 

 removal are factors of known quantity for 1952, 

 but they will be changed in subsequent years by 

 continuing forestry efforts. In application, these 

 factors were adjusted to account for changes in 

 the intensity of forestry expected from continua- 

 tion of recent trends. Projected net growth and 

 inventory thus include the effects of these trends. 



The "formula" approach has the following ad- 

 vantages: (1) Current gross gi-owth, mortality, 

 and ingrowth were known from results of initial 

 coverage by the Forest Survey and from other 

 sources; (2) changes in these factors were known 

 for areas where the Forest Survey had completed 

 the initial survey and one resurvey; and (3) the 

 effects of some forestry measures on these factors 

 were available from repeated measurements on 

 permanent sample plots in some parts of the 

 country. Therefore, the best information avail- 

 able was adaptable for direct use in formulae or 

 provided a suitable basis from which estimated 

 values could be made. A more detailed explana- 

 tion of procedures is given in the appendix under 

 Adequacy of Data. 



Even when the best basic data available are 

 used, statistics resulting from projections are not 



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