Western spruce budworm defoliation effects on forest structure and potential fire behavior.

Abstract

Forest composition and structure on the eastern slope of the Cascade Mountains have been influenced by decades of fire exclusion. Multilayered canopies and high numbers of shade-tolerant true fir trees interact with western spruce budworm to alter forest structure and to affect potential fire behavior and effects. We compared measurements taken in 1992 (early budworm outbreak) and 2000 (late budworm outbreak) from 21 permanent plots located in a late successional reserve south of Mt. Adams in Washington. Canopy closure decreased significantly, from a mean of 78% in 1992 to 43% in 2000, but the coarse woody debris load increased significantly during the same period, from about 40 Mg ha-1 to 80 Mg ha-1. Tree mortality was mostly in the smaller (

Citation

Hummel, S.; Agee, J.K. 2003. Western spruce budworm defoliation effects on forest structure and potential fire behavior. Northwest Science. 77(2): 159-169