SPRING PRECIPITATION AND HEIGHT GROWTH 



681 



varying from 15 to 30 inches, and that the strongest laterals were 

 generally within i foot of the surface. 



Depth, 

 feet. 



Character of soil. 



Moisture 



content, 



per cent 



dry weight, 



June 6, '13. 



Wilting* 



coefficient, 



per cent. 



Water- 

 holding* ca- 

 pacity, 

 per cent. 



Clayey loam, mixed with volcanic 

 rock fragments 19.2 



Loamy clay (adobe) mixed with 

 rock fragments and volcanic 

 cinders 21.3 



Adobe clay mixed with rock frag- 

 ments t 19.7 



Adobe clay mixed with rock frag- ' 



ments and volcanic cinders ! 21.0 



Adobe clay mixed with rock frag- 

 ments and volcanic cinders 24.6 



Adobe clay mixed with rock frag- i 



ments and volcanic cinders 24.9 



Adobe clay mixed with rock frag- ' 



ments and volcanic cinders 26.7 



12.7 

 14.8 



63-5 

 72.1 



*From samples on near-by plots. 



It is evident from the precipitation figures for 1913 that the pines 

 in that year depended entirely upon winter precipitation for their 

 height growth. Since the total precipitation in April, May, and June 

 was only 0.25 inch, it may be readily seen that an addition of 2 or 3 

 inches during this period would have resulted in an appreciable in- 

 crease in soil moisture and presumably in height growth. Such was 

 the case in 1914 and in a more marked degree in 1915 and 1917. 



If, as is often the case, the first of April marks the end of the season's 

 storms, a dry period of 3 months prior to the beginning of the summer 

 rains may be expected. Since yellow pine, on account of the low tem- 

 perature, does not begin growth until about the middle of May, a dry 

 period of 6 weeks intervenes between the last storm or the disappear- 

 ance of snow and the beginning of growth. During this period a large 

 portion of the stored moisture supply is dissipated without benefit to the 

 tree. If, on tlie other hand, belated storms continue through April 

 and into May, the stored water supply is not only conserved, but may 

 be actually augmented. A typical example of the first type of spring 

 was in 1916. Despite a winter precipitation of over 16 inches, the 

 highest on record in 9 years, soil moisture conditions, after it became 

 warm enough for growth, were decidedly below normal. This condi- 

 tion was indicated not only by the poor growth of natural reproduction. 



