FOREST RESOURCES OF THE NORTH-LOUISIANA DELTA 



Timber Increment 



•^ 



CURRENT net increment, as considered in 

 this report, is the difference between the net 

 \olume of Uve good trees standing in the unit 

 January 1, 1934, and the corresponding vohime 

 that, according to Forest Survey estiiTiates, would 

 have been standing on January 1, 1935, if there had 

 been no volume removed in cutting during the year. 

 It is the increase over and above the volume lost 

 through natural mortality. The board-foot loss 

 through natural mortality is equal to approximately 

 four-fifths of the net board-foot increment and the 



4^ 



corresponding cubic-foot loss is equal to approxi- 

 mately 85 percent of the net cubic-foot increment. 



Board-Foot Increment 



Board-foot increment comprises two elements 



(1) the growth on trees already of .sawlog size and 



(2) the total board-foot volume of trees coming into 

 sawlog size during the year. This increment is ex- 

 pressed in net woods scale, that is, the gross scale of 

 usable sawlogs. It is based on good trees only, and 



Table 10. 



— Total woods net 



annual inct 



ement (Scri 



hner log scale) ' classified according 



to forest condition 





Forest condition 



Increment ' in trees 

 remaining under 

 sawlog size 



Increment 

 growing 

 size 



in trees 

 nto sawlog 



Increment in trees of 

 sawlog size 



Total increment 



Com- 

 mercial 

 area ^ 



Noncom- 

 mercial 

 area 



Com- 

 mercial 

 area s 



Noncom- 

 mercial 

 area 



Com- 

 mercial 

 area ^ 



Noncom- 

 mercial 

 area 



Com- 

 mercial 

 area ' 



Noncom- 

 mercial 

 area 



All areas 



Old growtli: 



Uncut . ^ __ 



Cords 

 12, 280 

 -40 



f 'nrds 

 4,460 

 9,400 



M hoard feet 

 4,100 

 2, 050 



M board feet 

 8,810 

 12, 070 



Mboardfced 

 7,490 

 10. 680 



if board feet 



2,020 



590 



Mboardfeet 



11, ,590 



12, 730 



M board feet 

 10, 830 

 12, 660 



i[ board feet 

 22, 420 



Partly cut 



25, 390 









Total . 



12, 240 



13, 860 



6,150 



20, 880 



18, 170 



2,610 



24, 320 



23, 490 



47, 810 









Second growth: 

 Sawlog size 



-48, 200 



1,240 

 21,170 



9,260 



30, 920 

 25,810 



98, 880 



870 

 -2,930 



108, 140 



31, 790 

 22,880 



139, 930 



t'nder sawloe size 



22.880 













Total 



-48, 260 



22,410 



9,260 



56, 730 



98, 880 



-2,060 



108, 140 



54, 670 



162, 810 













4,580 





110 





140 





250 



250 













\11 conditions 



< -36,020 



40, 850 



15,410 



77, 720 



117,050 



fiSO 



132,460 



78,410 



210,870 







1 Increment figures are based on the assumption that no cutting takes place. 



■ This volume increment includes the annual growth on trees 5 inches and larger in diameter, but under sawlog size, plus the volume (in cords) of trees 

 that during the year move into the 6-inch diameter class. 



3 The annual increment on commercial forest areas includes not only the increment on areas that were commercial forest at the beginning of the year, 

 but also the total timber volume added on commercial forest areas through the movement of areas from the noncommercial to commercial class as a result 

 of 1 year's growth. Negative board-foot increment on noncommercial forest indicates (1 ) that the volumes on areas moving from the noncommercial to the 

 commercial class were greater than the increment on areas remaining in the noncommercial class, and (2) that the mortality in residual stands is heavy. 



< Negative annua! cord-volume increments of trees under sawlog size may mean one of two things (or both) : (1) Either the volume of trees moving from 

 under sawlog size to sawlog size is greater than the increment in cords of the trees that were under sawlog size at the beginning of the year (see footnote 2); 

 or (2) the volume in cords on areas moving from the noncommercial to the commercial class is greater than the increment on areas that remain in the 

 noncommercial class. 



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