plus the volume of those reaching 5 inches during 

 the year. Reproduction and clear-cut areas have 

 an insufficient volume of trees 5 inches or larger to 

 justify increment calculations. 



Table 18. — Annual increment percent, 1 

 forest conditions 



species groups and 



BOARD-FOOT INCREMENT (BASED ON INTERNATIONAL 

 J4-LNCH RULE) 





Old growth 



Second growth 



Species group 



Uncut 



Partly 

 cut 



Sawlog 

 size 



Under 



sawlog 



size 



Turpentine pines: 



Round . . 



Turpentined. 



Nonturpentine pine 



Hardwood _. ... 

 Cypress 



Percent 



-1.18 



-6.96 



1.28 



1.97 



.96 



Percent 



-0.95 



-6.01 



1.38 



1.92 



.22 



Percent 

 8.12 

 -.43 

 4.37 

 4.76 

 2. 16 



Percent 

 15.66 



9.52 



7.18 

 .68 







CORDWOOD INCREMENT 



Turpentine pines: 



Round 



Turpentined 



Nonturpentine pine. 



Hardwood 



Cypress 



-1.77 



-2. 18 



4.35 



-7. 58 



-6.94 



-2.28 



.84 



1.40 



3.02 



1.38 



.99 



3.51 



.52 



-.02 



1.74 



8.92 

 -4.07 

 7.21 

 7.05 

 1.74 



1 The increment percents are periodic annual compound interest rates 

 based on a 10-year period computed for good trees only. 



INFLUENCE OF TURPENTINING AND FIRE 

 ON INCREMENT 



In northeastern Florida the natural conditions of 

 soil and climate in general are favorable for tree 

 growth, but there are several factors that have 

 tended to restrict volume increment. Chief of 

 these is an abnormally high mortality rate, es- 

 pecially in the turpentine pines. This must be 

 charged mainly to practices that have prevailed 

 in the past in the production of gum turpentine 

 and rosin and in woods burning. Deep chipping, 

 hanging too many cups on the trees, cupping small 

 trees, inserting tins too deeply, and failure to 

 protect resting or worked-out turpentine trees 

 from fire have not only materially retarded the 

 diameter growth of the individual trees and reduced 

 their volume of merchantable saw timber, but have 

 in addition resulted in an abnormal loss of trees 

 (fig. 9). Wholesale woods burning is most com- 

 mon in longleaf and slash pine types. 



The reduction in rate of growth and the increased 

 rate of mortality of turpentined trees accounts for 

 the negative increment for that species group 

 (table 18). The remaining round old-growth 



Figure 9. — Wind damage in second-growth slash pine stand, Union County, Fla, 



33 



