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Pacific Southwest Research Station
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Albany, CA 94710-0011
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General Technical Report
Title: Ten-year risk-rating systems for California red fir and white fir: development and use
Author: Ferrell, George T.
Source: Gen. Tech. Rep. PSW-115. Berkeley, Calif.: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 12 p
Station ID: GTR-PSW-115
Description: Logistic regression equations predicting the probability that a tree will die from natural causes--insects, diseases, intertree competition--within 10 years have been developed for California red fir (Abies magnifica) and white fir (A. concolor). The equations, like those with a 5-year prediction period already developed for these species, are based on analysis of crown and bole characteristics of trees, and are readily programmed into pocket calculators for field use. For user convenience, the equations are formulated into Award-Penalty Point Systems, in which a tree is awarded or penalized points on the basis of ratings of its crown characteristics. The resulting Risk Point Total is related to the percentage of a hypothetical population of identical trees expected to die within 10 years. Three risk classes (low, medium, and high) are defined and depicted for rapid visual estimation of risk in applications where a more precise estimate is not required.
Key Words: Abies concolor, Abies magnifica, California, mortality, risk-rating, bark-boring insects, tree diseases
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Ferrell, George T. 1989. Ten-year risk-rating systems for California red fir and white fir: development and use Gen. Tech. Rep. PSW-115. Berkeley, Calif.: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 12 p.
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