U.S. Department of Agriculture: Animal and Plant Health Inspection Service


Date of this Version



Published at Univ. of Calif., Davis. 2014. Pp. 419-422.


U.S. Government Work


In parts of the Pacific Northwest, black bears emerge from winter dens with depleted fat reserves and feed on mature conifers by stripping bark and consuming sugar-rich sapwood. Peeling by bears affects commercial conifers through direct loss of the tree or degraded log quality at stand harvest. Bears generally peel trees from 15-30 years old in intensively managed forests until preferred foods such as fruits and berries are available, and a single bear can peel several trees per day. Dying trees have a signature red canopy and are detected in annual aerial forest health surveys; however, trees that scar over peeling are not detected by aerial surveys. Previous studies reported results of damage summaries for northwest Oregon from flights, adjusted for bias; however, they offered no estimates of economic impact. Using landowner survey data, another study estimated an annual timber loss to bears at approximately $11.5 million across part of western Oregon. While informative, these estimates used broad assumptions to derive primary impacts and did not address secondary impacts. We used aerial health surveys, the national land cover database, and the Regional Economic Models Inc. (REMI) PI+ model to estimate the primary and secondary (indirect and induced) impacts of bear peeling in western Oregon. Because the accuracy and precision of aerial estimates (i.e., percentage of dead trees/polygon) was unknown, we calculated 4 scenarios of loss: 1%, 10%, 30%, and 100% loss. Under these scenarios, black bear damage to commercial forests negatively impacted Oregon’s gross domestic product between $0.9-$89 million annually, and resulted in an annual loss of between 11 and 1,012 jobs in the state. We will explain our methodology in this study as well as current efforts to improve the accuracy and precision of damage estimates, and ultimately our understanding of the economic impacts of black bear peeling.

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