188 



TIMBER RESOURCES FOR AMERICA'S FUTURE 



heart rots 



other diseases 



DISEASES 



20 30 



PERCENT OF TOTAL 



40 50 



includes Coastal Alaska 



Figure 71 



Diseases had their greatest influence on growth 

 loss, largely because of heart rots. Hence in the 

 growth-loss category alone forest diseases ac- 

 counted for 57 percent of the estimated growth 

 loss in sawtimber from all causes. Because of 

 this high growth loss plus the mortality they 

 caused, diseases accounted for 19,889 million 

 board-feet of growth impact. 



Still other causes of loss also loom large in the 

 total effects from destructive agencies, mostly as 

 a result of weather factors, particularly wind, and 

 animal damage. These additional causes of loss 

 made up 18 percent of the total growth impact in 

 terms of sawtimber. 



The greatest total losses to sawtimber were in 

 the South, but the North, despite its smaller 

 forest acreage, suffered nearly as much damage. 

 The West was not far behind the North (table 114). 



Three regions, the Southeast, the Pacific North- 

 west, and the Lake States, together made up 47 

 percent of the total national sawtimber loss 

 (table 115). Disease and fire were primarily 

 responsible in the Southeast, animals and disease 

 in the Lake States, and insects and wind in the 

 Pacific Northwest. 



In general, fire had its greatest impact in the 

 South, particularly the Southeast and West Gulf, 

 and in the Central States, and its least impact in 

 the West. Disease impact was greatest in the 

 Southeast and most of the Nortli, but also ran 

 high in most other regions. Insects were worst in 

 the West, particularly the Pacific Northwest, 

 California, and the Northern Rocky Mountain 

 Regions. Animal damage was highest in the Lake 

 and Central States and parts of the South and 

 West, and wind was very damaging in the Pacific 



