868 JOURNAL OF FORESTRY 



A Study of the chart brings out the fact that the rainfall in 191 4, 

 while only average in amount, compared to the other years, was ver>' 

 evenly distributed during the period of most rapid height growth. 

 Good soaking rains occurred regularly at intervals of from four to ten 

 days from the middle of April to the middle of July, with smaller 

 showers between in most cases. The two rainy periods in June were 

 probably exceptionally favorable to growth. In each case a heavy rain 

 was preceded by lighter showers, giving the ground a chance to become 

 soaked to a good depth. The rainy period was then followed by a week 

 or so of warm, growing weather, with an abundance of soil moisture 

 available to the roots. 



In contrast to the year 1914, the other seasons show much more pro- 

 longed periods during which no heavy soaking rains occurred. Much 

 more irregularity in the quantities of rain during the different rainy 

 periods is also shown. Some were merely a series of light showers 

 which would not be able to penetrate the soil to any great depth. 

 Others, again, were heavy isolated rains which were concentrated over 

 short periods and preceded or followed by several days of dry weather, 

 leading to maximum loss from run-off and evaporation. The effect 

 upon growth of regularity or irregularity of distribution of rainfall 

 within the limits here shown is, of course, purely a matter of specula- 

 tion, but it is not unreasonable to think that moisture conditions in 1914 

 were at least fully as favorable, if not more so, than in any of the other 

 years. 



In conclusion, it must be admitted that the data here presented are 

 inadequate to definitely establish any clear relationship betW'Cen height 

 growth and climatic factors. Yet there is a consistent, if somewhat 

 circumstantial, series of indications which all lead to the tentative con- 

 clusion that the year 1914, with its relatively high temperatures, its 

 maximum of sunny days, and its sufficient and evenly distributed rain- 

 fall, produced favorable growing conditions which were directly re- 

 flected in the greater height growth shown for that year. Tempera- 

 tures in other years were just as high or higher; there were just as 

 many clear days, and rainfall was just as great and as evenly distrib- 

 uted. Yet in no case were all these favorable factors combined in the 

 same years and months to the extent shown in 1914. 



Taking the evidence of average amount of growth in the different 

 years as a basis, it seems justifiable, therefore, to conclude that rate of 

 height growth of larch seedlings does vary in accordance with varia- 

 tions in weather conditions from year to year, and that the most favor- 

 able conditions for rapid height growth are produced in the North 



