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

S. Hummel; J.K. Agee

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

Journal article

Open access

Peer reviewed

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

S. Hummel and J.K. Agee

Northwest science., Vol.77(2), pp.159-169

2003

Handle:

https://hdl.handle.net/2376/807

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Rights Statements InC/1.0 , Open Access

Abstract

botanical composition

dead wood

defoliation

fire behaviour

fire effects

forest damage

forest fires

forest pests

forests

insect pests

plant pests

stand characteristics

stand structure

Forest composition and structure on the eastern slope of the Cascade Mountains have been influenced by decades of fire exclusion. Multi-layered canopies and high numbers of shade-tolerant true fir (Abies) trees interact with western spruce budworm (Choristoneura occidentalis) to alter forest structure and to affect potential fire behaviour 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, USA. 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 approximately 40 to 80 tonnes ha-1. Tree mortality was mostly in the smaller (<20 cm) diameter classes. Potential surface fire flame lengths increased significantly from 1.4 m in 1992 to 1.9 m in 2000, but changes in torching potential and independent crown fire behaviour were not significant. Projections using the First Order Fire Effects Model indicate that a wildfire in conditions similar to those in 2000 would not be of stand replacement severity and would leave 148 trees ha-1 and more than 34 m2 ha-1 of basal area.

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Title: Western spruce budworm defoliation effects on forest structure and potential fire behavior
Creators: S. Hummel (Author)
J.K. Agee (Author)
Publication Details: Northwest science., Vol.77(2), pp.159-169
Academic Unit: Northwest Science
Publisher: WSU Press
Identifiers: 99900502313401842
Copyright: In copyright ; openAccess ; http://rightsstatements.org/vocab/InC/1.0/ ; http://purl.org/eprint/accessRights/OpenAccess
Language: English
Resource Type: Journal article