Climate and growth rate as related to an outbreak of silver fir beetles.

Abstract

In 1947, an outbreak of silver fir beetles, Pseudohylesinus grandis Sw. and P. granulatus (Lec.), was discovered in northwestern Washington. The epidemic flourished for the next six years, killing some 525 million board-feet of Pacific silver fir, Abies amabilis (Dougl.) Forbes. Prior to 1947, the silver fir beetles were considered to be of little economic importance because they had been observed to attack only slash, windthrows, and suppressed or otherwise weakened trees. While the recent destructive outbreak was in progress, it was reasoned that some factor or factors might have weakened the trees sufficiently so that these relatively non-aggressive beetles could kill them. Climate was suspected as a factor in weakening the trees. A study was undertaken, therefore, to determine whether a relationship existed between tree growth and weather patterns before and during the beetle outbreak.

Citation

Thomas, Gerard M. 1957. Climate and growth rate as related to an outbreak of silver fir beetles. PNW Old Series Research Notes No. 150, p. 1-4