DEPARTMENT OF BOTANICAL RESEARCH. 89 



During the summer of 1919 advantage was taken of several small 

 cuttings that had been made for carrying out a stem analysis of this 

 tree. WTien ages are plotted against diameters a straight-Une curve is 

 secured up to the age of 80 years, beyond which extremely few of the 

 trees survive. An average diameter (inside the bark) of 33 cm. (13.2 

 in.) is attained at the age of 30 years and of 57 cm. (22.8 in.) at the age 

 of 60 years. Some of the most rapidly growing individuals showed a 

 diameter (outside bark) of 58 cm. (23.2 in.) at 28 years and 98 cm. 

 (38.3 in.) at 60 years. 



On the stump of each tree measurements were made of the growth by 

 decades. The increase in diameter is greatest between the ages of 10 

 and 20 years, but the actual wood increment increases up to 80 years, 

 at which age the stump has an average area of 3,155 sq. cm. (489 sq. 

 in.). The greatest observed diameter growth was in a tree 113 cm. 

 (45 in.) in diameter which was felled at the age of 84 years and shov/ed 

 for its second decade an increase of 35 cm. (14 in.) in diameter. 



The Monterey pine is found both on the sandy soil of old stabilized 

 dunes and on a gravelly clay. The stem analyses were made on trees 

 which were nearly equally di\dded between sites with the two types of 

 soil. On plotting ages against diameters there is no discoverable 

 difference of growth-rate on the two soils. 



The elongation of the shoots commences at an early date in the spring 

 and continues at a slightly decreasing rate until September. Vigorous 

 young trees measured at monthly intervals showed on March 30 a 

 growth which proved to be an average of 38 per cent of the total growth 

 in height for the year. In a series of 350 young trees the percentage 

 of 1919 growth to previous height-growth was found to range from 86 

 per cent for seedhngs 10 to 20 inches in height down to 14 per cent for 

 saplings 200 inches in height. In exceptional cases the young seedlings 

 10 to 20 inches in height grew 160 per cent of their previous height in 

 the season of 1919. Particularly favorable conditions sometimes result 

 in a height-growth of as much as 10 feet in one year in trees 12 to 15 

 feet in height, and even greater growth has been reported. 



Unhke other pines, this species commonly forms one or two whorls 

 of branches on the shoots which are not yet one year old. The height- 

 growth of previous years can not, therefore, be determined from the 

 length of the intervals between whorls of branches. 



A comparison of height-growth with diameter-growth for the last 

 4 to 7 years in a number of saplings 12 to 15 feet high showed no 

 definite correlation, either positive or negative, between these phases 

 of growth. Exceptionally active height-growth appears to be con- 

 stantly correlated -with a small growth in diameter. The individual 

 conditions of crown development must be taken into account in a more 

 exact analysis of this correlation. 



