The board-foot drain from commercial forest 

 areas, including both high-grade and low-grade 

 material, expressed in the terms of the international 

 one-fourth-inch log rule (which closely approxi- 

 mates green lumber tally), exceeded the total incre- 

 ment from such areas by 66 percent, or 88 million 

 board feet (table 16). This drain, however, re- 

 moved mainly high-grade timber of certain species, 

 whereas it is estimated that approximately half the 

 increment was either in low-grade material or in 

 species not utilized by the existing forest industries. 

 It is apparent, therefore, that the drain from com- 

 mercial areas of material of the grade and species 

 used by forest industries was much more (approxi- 

 mately 3)^ times as great) than the increment of the 

 same grade and species on commercial areas. 



Table 16. — Comparison oj board-joot increment ' with drain in 

 1934 {International \-inch rule) 



Item 



Commercial 

 area 



Total forest 

 area 





Million board 

 feet 



4. 635. 4 



133.3 



221.6 



4, 547. 1 



88. 3 



Million board 

 feet 



10,091.4 

 210.2 

 321 



1934 increment 



1934 drain 



Net growing stock, January 1935 . 



9, 980. 6 



Net decrease 



110 8 









1 In calculating the increment, appropriate allowance was made for 

 the growth on the volume in trees cut during the year. 



Table 17. — Comparison of cubic-Joot increment ' {excluding bark) 

 with dram in 7934 



Item 



Volume in good 

 trees 



Volume 



in 

 sound 

 culls 3 



Volume 



in 

 rotten 

 culls < 



Total 



Stem 

 wood 2 



Top 

 wood 



volume 



Net growing stock, January 

 1934 



Million 

 cubic 

 feet 



2, 359. 96 

 44.83 

 51.74 



2, 353. 05 

 -P. 91 



Million 



cubic 



feet 



994. 39 



18.89 



29, 00 



983. 68 

 -10.71 



Million 



cubic 



feet 



334. 45 



6.36 



7.10 



333. 71 



-.74 



Million 



cubic 



feet 



59.12 



1.12 



.95 



59.29 



+.17 



Million 



cubic 



feet 



3 747 92 



1934 increment .. 



71 '^0 



1934 drain 



Net growing stock, January 



1935 



Net change 



89.39 



3, 729. 73 

 -18.19 



1 In calculating the increment appropriate allowance was made for tlie 

 growth on the volume in trees cut during the year. 



2 Includes the cubic contents of the stems of good trees of sawlog size, 

 but does not include the top wood; also includes the main stem of good 

 trees under sawlog size to a variable top, never under 4 inches and seldom 

 over 8. 



3 Includes both stem wood and top wood in sawlog- and under sawlog- 

 size trees. 



* Includes sound volume in rotten cull trees, both sawlog size and 

 under sawlog size; also includes both sound stem wood and top wood. 



For the total forest area, comparison of the board- 

 foot increment and drain shows that drain exceedep 

 increment by 53 percent. When this percentage is 

 compared with the 66 percent for the commercial 

 area, it is evident that commercial forest areas were 

 being depleted at a more rapid rate than the forest 

 as a whole. On the basis of data in table 16 and 

 the statements in the preceding paragraph, it is 

 estimated that the volume of timber of the class 

 actually being cut from commercial areas was 

 depleted approximately 155 million board feet in 

 1934. Since this figure is greater than the 111 

 million board-foot depletion of the total forest 

 area by approximately 44 million board feet, the 

 latter figure represents the accretion in timber of a 

 class not then being utilized by the forest industries. 

 Thus, although the total saw-timber volume of the 

 forest was actually being reduced, the growing 

 stock in material that could not be practically util- 

 ized by the present forest industries was being 

 built up. 



It should be emphasized again that the board- 

 foot increment is net after an allowance for a sub- 

 stantial loss through natural mortality. If it were 

 practicable through improved management to sal- 

 vage as much as 75 percent of this mortality loss, 

 even without any increase in growth rates, the 

 board-foot increment would balance appro.ximately 

 the 1934 board-foot drain for the total forest. 



COMMERCIAL TOTAL FOREST 

 AREAS AREA 



TOTAL FOREST 

 AREA 



Figure 10. — Comparison of increment and drain during 7934 



33 



