44 Forest Club Annual 



stated, the occurrence of a vegetative period in the tree is the 

 response to a summation of seasonal factors, and it would be a 

 poor observer indeed that notes definitely the result without paus- 

 ing to speculate on the causes. The best thing that can happen 

 to a student of forestry would be to get out among the trees, to 

 wonder why and how, and then look about him for the answer. 



The results to be obtained from phenological records are 

 many. They are of interest to plant physiologists as they are 

 useful in the study of the life functions. The data worked up 

 into tree calendars should be useful in schools and colleges. In 

 forestry such information has a direct economic value in seed 

 collection and a less direct value in silvicultural considerations. 



In working up phenological data a very convenient form is 

 that of a chart showing the time at which the functions of the 

 different species occur. Data for one year can be used to show 

 not only the date of the occurrence of the flowering, leafing, and 

 fruiting, but its duration. Where records extending over several 

 seasons are available the chart can be made to show the annual 

 variation in the occurrence of each function. For such a chart 

 it would be necessary to decide whether, for instance with flower- 

 ing, the date of first appearance of flowers or the date of general 

 flowering would be the most desirable. Then the length of the 

 area occupied by any color on the chart would record the seasonal 

 variation in that time. 



The following scheme* (Plate I) is offered as a suggestion 

 for a graphic way of compiling this data. It can be varied to suit 

 the data available and the results to be presented. 



*A chart of this kind has been prepared for 72 of the common species of 

 the United Sfates and will appear in an early issue of the Monthly Weather 

 Review. 



