RATE OF GROWTH 



85 



The longleaf shows for the first five to seven years hardly any development in height, and 

 begins then to grow rapidly and evenly to the fiftieth or seventieth year, and even after that 

 period, though the rate is somewhat diminished, progresses evenly and steadily, giving to the 

 height curve a smooth and persistent character. 



The diameter growth shows the same even and persistent progress from the start, and the 

 volume growth also progresses evenly after the rapid height-growth rate is passed at seventy 

 years. 



The Cuban pine ceases in its maximum rate of height growth at thirty years, starts with its 

 diameter growth at about the rate of the loblolly, but alter the twenty-fifth year leaves the latter 

 behind for the next twenty-five to thirty years, then proceeds at about the same rate, but 

 persisting longer than the loblolly. At the age of fifty years the Cuban pine with 40 cubic feet 

 has made nearly twice the amount of the loblolly and more than four times that of the longleaf j 



1(0 S^c 



100 



t 





























50 













3^ 



£-*•*"**""' 









o 









80 













3^ 



$s^ 





.^»—«<" 



$&4 



nScJ^ 



v^^-^ 







70 















*yt£>** 

















60 































50 































40 































30 































20 J 































10 f/j 































f£S i 



2 



3 



4 



5 



Q 



7 



& 



9 



li 



)0 I 



12 



U 



34 



0& ISO 



1*10-. 1— Diagram showing comparative progress of height growth in average trees. 



but at one hundred years the difference is reduced, being then 115, 90, and 55 cubic feet, respec- 

 tively, for the three species. 



Both loblolly and shortleaf pine reach their maximum growth sooner than the other two 

 species. While these still show a persistently ascending line at one hundred and twenty to one 

 hundred and forty years, the rate of growth in the loblolly shows a decline after the one-hundredth 

 year, and the shortleaf has done its best by the eightieth year. These facts give indications as to 

 the rotation under which these various species may be managed. 



As stated before, the growth of trees, especially in the virgin forest, is quite variable even for 

 the same species and same soil conditions. An average, therefore, like the one presented in the 

 diagrams, however perfect, could apply only when large numbers are considered. Thus there are 

 fast-growing trees of longleaf and slow growing of Cuban or loblolly pine. Yet the diagrams will 

 fairly well represent the average growth, with the possible exception of the Cuban pine, for which 

 the number of measurements was too small to furnish reliable data. 



