396 R 1\ Patton: 



It will be noted that the curves for local tr<ies indicate a "very 

 rapid growth from the coniniencement. Professor Masson has 

 kindly pointed out that the curve for Mountain Ash is a mass 

 action curve, and that this particular curve gives a remarkable 

 set of constants. The question of growth curves cannot be dis- 

 cussed here, but suffice it to say that the Eucalypt appears to be 

 anomalous. In general it may be said that the growth curve 

 contains a point of inflexion — the gradient is at first increasing 

 and subsequently decreasing. It is interesting to notice that 

 Blackwood, an associate of Mountain Asli, has the same type ol 

 graph. Pinus insignis has a similar graph. Blackwood has been 

 reputed a slow growing tree, but there is no evidence of this. It 

 will be seen that good cabinet timber could be grown in 40 years. 

 This rapid increase of diameter materially affects the management 

 of the forest. It has ceen frequently stated in the press that we 

 can regrow our forests in 40 years, but a detailed study of the 

 forest fails to reveal any evidence of this. It is said that Moun- 

 tain Ash will grow a butt of from 30 inches in 40 years. Indi- 

 viduals may do this, but we are concerned with the average over a 

 wide area. 



If we apply Schneider's fornmla p = 4:00/(1.71, where p = rate per 

 cent, at which wood is being produced, g? = diameter and 7i=num- 

 ber of rings in the last inch, we find that in Mountain Ash at the 

 ^Oth year, p=l.^%. Under skilful management it is more than 

 probable that this rate could be considerably increased. The fuller 

 the crown kept on the tree, the more timber formed. A study of 

 the big timber shows that the rate of increase is below 1 %, and it 

 is more than likely that in the virgin forest increase is compen- 

 sated by decay. The fixation of a diameter limit for felling with- 

 out reference to rate of growth has no justification. 



Height. — The heights were taken either with an Abney level and 

 tape, or measured along the ground as the trees were felled. 

 While it was a simple matter to get a curve for diameter growth, 

 it was not an easy matter to get a curve for height. If we had 

 patches of trees of known age the matter would have been simple. 

 The objection to the Schlich method for obtaining a height curve 

 has already been pointed out. The method adopted here was to 

 establish a relation between diameter and height and, to plot 

 these results, diameter against height. This was done for a large 

 number of trees growing in close canopied high forest, but only 

 normal trees were measured. 



