252 



Thus, at 35 feet from the ground there were only 91 annual rings as against 97 at the base. This 

 means that the part of the tree above 35 feet had been in existence only ninety-one years, so that it took 

 97-91 — 6 years, for the tree to reach a height of 35 feet. Thus the following table is prepared . — 



Height of section 

 in feet. 



Number of rings. 



Number of years 



taken to reach 

 height of section. 







5 



15 



25 

 35 

 45 



55 



65 



95 



140 



97 

 97 

 95 

 93 

 91 

 88 

 85 

 79 

 53 

 



2 

 4 

 6 

 9 



12 

 18 

 44 

 97 



From this table a curve showing height at different ages is plotted (see Fig. 1, not reproduced, J.H.M.). 

 The very rapid height growth in the first twelve years should be noted as it has an important economic 

 bearing on the regeneration of the forests. A species capable of such rapid growth in early youth is not 

 likely to be suppressed by weeds, and consequently expenditure on early cleanings will probably not be 

 necessary. Compare the figures for E. globulus, in Tasmania, quoted at p. 245. 



A further abstract of Mr. de Beuzeville's researches is found in " The Australian Forestry Journal," 

 for January, 1918". 



' The forest of E. gigantea at Buddong appears to be of comparatively recent origin, and is rapidly 

 establishing itself in the surrounding forest of Eucalyptus coriacea and E. rubida. A noteworthy feature 

 is that trees evidently well past maturity are sound to the heart and absolutely free from disease. 



The specimen selected for analysis was a typical tree of a typical forest of the species. The annual 

 rings were clearly defined through the whole of the cross sections, and varied very little in width. The 

 tree was well grown, with a good crown, and apparently still vigorous. 



A remarkable circumstance was the rapid height growth during the early life of the tree, and this 

 is shown in a series of graphs which accompany the treatise, and disclose the following . — 



Growth in height . — 2J years, 20 feet ; 6 years, 40 feet ; 14 years, 60 feet ; 20 years, 68 feet ; 40 years, 

 '90 feet; 60 years, 110 feet; 80 years, 126 feet; 96 years, 140 feet. 



Growth in diameter . — 2 years, 1 inch; 6 years, 2i inches; 14 years, 6 inches; 20 years, 9 inches; 

 40 years, 18 inches ; 60 years, 2S inches ; 80 years, 36 years ; 96 years, 42 inches. 



Volume of wood: — 20 years, 20 cubic feet; 40 years, 75 cubic feet; 60 years, 180 cubic feet: 80 

 years, 300 cubic feet; 96 years, feet 420 cubic feet. 



Calculation on the results of an examination of the area of the cross section at various ages shows 

 that the tree reaches absolute maturity about the ninetieth year, when it will yield almost 5,000 superficial 

 feet of timber. 



Mr. de Beuzeville states that the bark amounts to 12 per cent, of the volume of the stem, the very 

 low percentage being accounted for by the thin nature of the bark on the upper portion of the trunk. In 

 conclusion, he remarks that his analysis discloses that " the tree does not reach absolute maturity at the 

 early age often attributed to it, but maintains a vigorous growth long after it has reached the dimensions 

 of a millable log. The present minimum felling girth is 7 feet over bark, and is apparently reached in 

 forty to fifty years. The problem is, therefore, whether if will be most advantageous to operate on the 

 species as at present, or whether the cutting age should be deferred until maturity, when greater volume 

 has been attained." 



