REPORT OF THE SOCIETY 



21 



the vast amount of debris that Utter the floors of our forests, affording a limitless 

 supply of highly combustible waste material, and finally butt and heart rots 

 are dominant influences in relation to the succession of cover types in unregul- 

 ated forests. Fortunately they are almost altogether restricted to mature 

 or suppressed timber; young trees are practically immune. This fact greatly 

 simplifies the problems of control and gives assurance that they will be largely 

 solved in the administration of anj' good policy of forest management. 



One of the unexpected drawbacks encountered in investigating Irutt and 

 heart rots has been the lack of information on even the identitv of the causal 



Fig. 5. — A common scene in an over-mature forest. Both the red pine and the balsam at the 

 lower right were severely butt-rotted. Not infrequently a large proportion of the affected 

 trees in such areas are brought to the ground by the wind or their own weight. 



organisms. Balsam rots may be cited as an extreme case; though several 

 types occur in living balsam trees, nobody as yet, so far as the literature shows, 

 has definitely established a connection with a specific causal factor in any 

 single case. To help meet this situation investigations were begun two years 

 ago, and are now being carried on with fruitful results. The methods employed 

 include those so successfully used in cultural diagnostic studies of bacteria. 



But there are other fundamental problems of even greater importance 

 calhngfor solution, such, for example, as the rate of progress of heart and butt 



