DISEASE CONTROL AND FOREST MANAGEMENT ' 



By F. H. MilIvUn 

 Assistant to the State forester of Texas 



Heretofore in the practice of forestry, both in this country and 

 abroad, the probabiHties concerning the condition of the stand in the 

 future have been given little or no weight in the calculation of the 

 allowed annual or periodic cut in the managed forest, but much devia- 

 tion from the prescriptions of the working plans has been made neces- 

 sary in many cases on account of various more or less severe catastro- 

 phes, due to several causes, which have exposed the stands to danger 

 of loss. This discrepancy between plans and execution has evidently 

 been due to a lack of data concerning the components of the total loss 

 factor, which should be considered in the calculations. Some of these 

 components, such as windfall, will always present a variable degree of 

 uncertainty, and all of them require detailed and careful observation 

 over long periods to determine with any degree of accuracy their rela- 

 tive importance. Meinecke (1915) brings out the difficulties encoun- 

 tered and possibilities revealed in his development of a study of decay 

 in its relation to one species of timber tree. His conclusions apparently 

 constitute the first attempt ever made to modify the calculations for 

 regulation in a definite way with regard to any one loss factor. This 

 work deals exclusively with the liability of young merchantable and 

 mature trees to loss through decay, but suggests other factors of loss 

 which deserve consideration, such as fire, snow-break, lightning, wind- 

 fall, insect injury, disease, etc. These factors vary in their suscepti- 

 bility to definite determination. Some efifort is generally made to con- 

 sider carefully the factors of snow-break and windfall in the determi- 

 nation of and marking for the silvicultural method for the forest. 

 Lightning and frost damage cannot be eliminated, but are found usually 

 in more or less definite zones or areas, and the species managed for or 

 favored on those areas should be selected with due consideration for 

 their resistance to those causes of injury. The fire danger may be ap- 

 proached from the same direction where fire-resistant species can be 

 utilized, but by far the most important field of action in this connection 

 is that of protection from fire, such as is already widely attempted with 



^ Prepared in co-operation with Professors Rankin and Recknagel. Reviewed 

 by Doctor Meinecke. 

 974 



