from these trees excludes woods cull, that is, those 

 rotten, crooked, and crotched stem sections which 

 ordinarily are left in the woods. It does, however, 

 include such cull as shake, sweep, and rot that is 

 ordinarily taken to the sawmill. 



On the basis of the net woods scale, the total 1934 

 increment was nearly 211 million board feet, 

 Scribner rule (table 10). Of this total, 93 million 

 board feet or approximately 44 percent is accounted 

 for by the volume of small trees becoming of sawlog 

 size during the year. A substantial part of the 

 remainder grew on trees that were in the 14- to 

 1 8-inch diameter classes at the beginning of the 

 year. Nearly 66 percent of the total increment was 

 on the second-growth sawlog-size areas, while only 

 10 percent was on the old-growth uncut area. 

 Nearly 63 percent, or 132}^ million board feet, 

 occurred on commercial forest areas. This includes 

 the total volume on areas which entered the com- 

 mercial classification during the year as a result of 

 increases in volume and improvement in quality 

 of the trees. 



Table 11 shows the average annual increment per 

 acre in 1934 on commercial and noncommercial 

 areas in the various forest conditions. The weight- 

 ed average increment expressed in net woods scale 

 for all types and conditions in the entire forest area 

 was 78.6 board feet per acre; the average annual 

 increment for the overcup oak-bitter pecan type, 

 where growth conditions are generally the least 

 favorable, amounted to only 42.5 board feet per acre. 



The board-foot increment per acre is substan- 

 tially greater in the second-growth sawlog-size con- 

 dition than in any other forest condition. In 

 second-growth, sawlog-size stands the annual in- 

 crement per acre on commercial areas is half again 

 as large as that on noncommercial areas. By con- 

 trast, in old-growth uncut stands the annual incre- 

 ment per acre on commercial areas is about one- 

 third of that on noncommercial areas. This large 

 difference between old-growth and second-growth 

 stands is chiefly due to the preponderance of over- 

 ripe, decadent timber in the former, whereas the 

 difference in the rate of growth on commercial and 

 noncommercial areas of similar condition is largely 

 clue to differences in stocking. 



Table 11. — Woods net annual increment'^ per acre classifier/ 

 according to forest condition and general type group 



Forest condition 



Commercial area: 



O'ld growth, uncut 



Old growth, partly 

 cut 



Second growth, saw- 

 log size 



Noncommercial area: 



Old growth, uncut 



Old growth, partly 

 cut 



Second growth, saw- 

 log size 



Second growth, under 

 sawlog size 



Clear-cut and repro- 

 duction 



.^.11 conditions 



Mixed hard- 

 wood 2 



Overcup 



oak-bitter 



pecan 



.\11 t 



Board 

 feet 

 17,2 



Cubic 

 feet 

 7.5 



Board 



feet 

 20, 1 



Cubic 

 feet 

 6, 6 



B'md 

 feet 

 17,9 



4.4 



6.5 



5,4 



3,0 



4,6 



2:36. 9 



39.9 



130, 6 



20, 



233, 7 



47.5 



13.0 



50,3 



9,5 



49,9 



51.0 



11.5 



29,5 



0,4 



42,0 



153.1 



26.7 



69,8 



18, 



140. 5 



61.1 



26,2 



52, 



9,9 



.59,9 



2,2 



2,0 



'-1. 1 







1.7 

 78,6 



94.3 



20.7 



12, 5 



,S, 7 



Cubi 



feet 



(. 3 



5. 9 

 39, 3 

 10, 



8.9 

 25.5 

 24 



1,(1 

 17, 1 



1 The increments per acre represent the difference between the average 

 volume per acre in the given forest type and condition at the beginning 

 and end of the growing season. Natural mortality is accounted for, but 

 not cutting. Board-foot volumes are Scribner log scale. Cubic-foot 

 increment represents the growth of sound stem wood, excluding bark; in 

 good trees at least 5 inches In diameter, plus the total volume of small 

 trees growing up to and exceeding this diameter during the year. 



'' Includes all types mentioned in table 5 except overcup oak-bitter 

 pecan. 



'' Negative increments occur where the volume lost to the stam 1 through 

 natural mortality is greater than the annual increment. 



Cordwooa Increment 



In addition to the saw-timber increment, there 

 are approximately 419,000 cords of annual incre- 

 ment in material suitable for cordwood only. The 

 composition of this total cordwood increment is as 

 follows, the last three items being approximations 



only: 



Cords 



.Stem wood of good trees under sawlog size 5, 000 



Top wood of good trees of sawlog size 300, 000 



Stems and tops of sound cull trees 97, 000 



Sound portion of stems and tops of rotten cull 



trees 17, 000 



Total 419,000 



The cordwood increment of good trees under 

 sawlog size is surprisingly small because of the 

 large proportion of them which move into sawlog 

 size. 



25 



