Weather and tree growth associated with white fir mortality caused by fir engraver and roundheaded fir borer

Abstract

White fir (Abides concolor [Cord. & Glend.] Lindl.) stands in Western North America periodically suffer extensive tree mortality caused by outbreaks of the fir engraver bark beetle (Scolytus ventralis Lec.). The cambial zone of the boles infested by S. ventralis is also colonized by the roundheaded fir borer (Tetropium abietis Fall)(Struble 1957). Only a few of these outbreaks have been related to underlying environmental factors, such as drought or host tree defoliation (Stevens 1971, Wickman 1963). The dearth of long-term, quantitative estimates of the population levels of these insects and the associated fir mortality has hampered better understanding of factors influencing these outbreaks.

Citation

Ferrell, George T.; Hall, Ralph C. 1975. Weather and tree growth associated with white fir mortality caused by fir engraver and roundheaded fir borer. Res. Pap. PSW-109. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 18 p