18 Transactions. 



to nearly an inch in diameter. The rate of growth continued very high 

 for the next group of twenty-five rings, 4-62 in. of radius being built up, 

 and was considerably above the average in the following one. During the 

 seventy-five years covered by these three groups the tree increased its 

 diameter by 2 ft. 6 in. 



After the 425th year of the age of the tree, or fifty-one years before 

 the present time (1913), a remarkably sudden slackening in the rate of 

 growth took place, only fin. of woody tissue being formed during the 

 next twenty-five years, although 3 - 12in. had been produced during the 

 previous twenty-five. The rate did not nearly recover itself before the 

 tree was cut down, the increase of woody tissue during the last twenty- 

 six years occupying only 1-18 in. I was able to prove, however, that 

 the slackening in growth was mainly a local peculiarity, confined to one 

 portion of the circumference of the stem, for by planing to the right 

 and left of the track along which the measurements had been made the 

 crowded rings were seen to gradually open out until they occupied a greater 

 diameter. 



My main object in drawing attention to the peculiarities of the 11 ft. 

 tree is to show how dangerous it is to estimate the age of any tree from 

 counting the annual rings of part of a section only. If, for instance, the 

 rings in the present example were known for only the 5 in. nearest the 

 centre, or the 5 in. nearest the circumference, then for those portions 

 the rate of fifteen rings per inch could be established, and, calculating on 

 that basis alone, the age of the tree would be 990 years. On the other hand, 

 if a portion in the centre had been selected — say, from the 225th to the 300th 

 rings — then the average number of rings per inch would not exceed five, and 

 the age of the tree would work out at 330 years only. On an actual count 

 of the whole of the rings, the age of the tree was ascertained to be 476 years, 

 the percentage of the annual rings to each inch of the radius being 7-2. 



One point of some importance still remains to be mentioned. At 

 page 144 of the " Forest Flora " Mr. Kirk says, " It is uncertain whether the 

 kauri forms only a single cylinder of wood during each year or more : the 

 balance of evidence is in favour of the latter view." Kirk nowhere states 

 the nature of this evidence ; nor does he act upon the belief in his calcula- 

 tions as to the probable age of the tree, all of which are based on the assump- 

 tion that only one cylinder is produced in each year. Obviously, the rings 

 of growth would be of little value for determining the age of the tree if there 

 was any uncertainty as to their being of yearly production. Fortunately, 

 however, this uncertainty has been removed by direct evidence. In the 

 year 1865 several young kauri-trees and certain New Zealand taxads were 

 planted in the Auckland Domain. In 1905 it became necessary to remove 

 some of them, and at my suggestion Mr. James Stewart obtained cross- 

 sections of the trunks. In all cases the number of concentric rings of growth 

 agreed with the number of years since the trees were planted. Mr. Stewart's, 

 results, which are embodied in a paper printed in our Transactions (vol. 38, 

 p. 374) may be taken as proving that the New Zealand gymnosperms do 

 not produce more than a single well-defined cylinder of woody tissue in 

 each year. 



The conclusions that can be drawn from this investigation may be sum- 

 marized as follows : — 



1. That the statements made regarding the age and rate of growth of 

 the kauri have for the most part been greatly overestimated, and par- 

 ticularly so for trees exceeding 5 ft. or 6 ft. in diameter. 



