Photos from the WFIWC Archives:
Control Methods

   

F. P. Keen developed this country's first system of classifying pine trees by their susceptibility to bark beetles. Beetle-caused loss was prevented by silvicultural removal of the relatively small susceptible component. His classification consisted of 16 classes combining age and vigor. Subsequently, Salmon & Bongberg developed the California Risk classification composed of only 4 classes. The class of a tree was determined primarily by visually rating its crown condition. The resultant conflict between these parties and the two classifications was resolved by considering "susceptibility" to be long-term and "Risk" to be short-term. When Bongberg transferred from Berkeley to the new Albuquerque Lab in 1952, M. Furniss assumed the assignment of maintaining risk plots at Blacks Mountain Experimental Forest, Lassen Co., California, and teaching foresters to apply the method. These photos were used in a study of the rate of change of risk of a tree. Above left: Low risk tree exhibiting normal crown characteristics (photo no. 15693 by M. M. Furniss, 1953), and high risk tree (above right) with severely deteriorated crown (photo no. 11441 by C. B. Eaton, 1940) WFIWC archives. (Furniss & Wickman 1998, Fig.5).

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