INTERPRETATION OF THE CURVE OF THE SEQUOIA. 



161 



older trees were sickly and were cut by accident, that is, the purpose was to cut young 

 trees, not over 100 years of age, but those of group B, having grown slowly, appeared 

 younger than they actually were. Hence their curve is low and has few variations, but 

 it agrees fairly well with that of the younger trees. Both curves have maxima in 1881, 

 1885, 1888, 1900, and 1903, and the maximum of 1907 in the lower curve agrees with a 

 marked increase in growth in the upper curve followed bj^ a maximum the succeeding year. 

 A marked difference in the curves is seen in 1890, where the younger trees much increased 

 then- growth while the older trees remained practically stationary. This seems to mean that 

 the very young and rapidly growing trees of group B were stimulated by the heavy rains of 

 1889 and 1890, while the older trees were unaffected. Apparentlj' the stimulus given to 

 the young trees gave them such vigor that its effects did not disappear for 15 years. 



1880 1890 1900 1910 



Group B =5 Sequoias at 

 Dillonwood. 



Group A - 19 Sequoias at 

 Dillonwood. 



15 



(■Rainfall at Porterville 

 loj 15' 



10 



■0.50 



■0.50 



Mean rainfall of 

 Tulare and Visalia 



Differential growth 

 of 24 Sequoias (groups 

 A and B) at Dillonwood 



Fig. 42. — Rainfall at Portersville Compared with Growth of Sequoias at Dillonwood. 

 (See Table I, pp. 328-329.) 



WTien the curves of growth are compared with the curves of precipitation it appears at 

 once that they do not agree at all closely, nothing like so closely as in the cases cited by 

 Professor Douglass ; yet on closer examination it appears that there is a certain amount of 

 agreement, although this is by no means noticeable. For instance, in 1881, 1890, and 1897 

 the curve for the larger number of trees — that is, group B — and the rainfall curves are both 

 at a maximum. In 1895 the rainfall curve reaches a maximum, which does not appear in the 

 tree curve, apparently because of the very dry year just preceding. In 1901 the rain is 

 again at a maximum, and the tree curve is high, although the maximum growth was attained 

 a year earlier. In 1905 and 1906 a marked disagreement is noticed, for in those years the 

 rainfall was uncommonly heavy, while the trees grew uncommonly slowly. This seems to 

 be due to the fact that the preceding years had been dry and therefore the growth of the 

 trees had been much checked. In 1906 the rain at Portersville and Tulare did not come in 

 great abundance until March, April, and May, during which months over 12 inches fell at 

 Portersville instead of the usual 3.25 inches. Much of this, coming so late, ran quickly off, 

 yet part of it was probably retained, and the way thus prepared for the rapid growth of 

 the trees in 1907. 



12 



