Canadian Forest Service Publications

Historical and spatial characteristics of spruce budworm Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae) outbreaks in northeastern British Columbia. 2002. Burleigh, J.S.; Alfaro, R.I.; Borden, J.H.; Taylor, S. Forest Ecology and Management 168: 301-309.

Year: 2002

Available from: Pacific Forestry Centre

Catalog ID: 20556

Language: English

CFS Availability: Order paper copy (free)

Abstract

The historical pattern of outbreaks of the spruce budworm, Choristoneura fumifenara (Clem.), in white spruce stands in the Fort Nelson Forest District of northeastern British Columbia was reconstructed with the use of dendrochronology. Outbreaks occurred on an average every 26 years, with 5-6 outbreaks in the past century in the northern regions of the district, while southern regions experienced between 0 (the most southern sites) and 4 outbreaks. In the northern regions, outbreaks began about 10 years earlier and the period of defoliation was longer than in the southern regions of the district. The southern limit of the range of the spruce budworm in British Columbia is marked by the predominance of the Montane Boreal White and Black Spruce biogeoclimatic subzone that has cool and wet summers that may not favor budworm development. Therefore, outbreaks that begin in the more suitable northern habitat would move southward only when favorable environmental conditions develop. Along with the high number of outbreaks in the northern regions of the district, there has been no direct control of the budworm, and overmature stands are maintained through suppression of fire and lack of harvesting. Many of these stands are entering a state of general decline with protracted mortality, resulting from a complex of secondary insects and pathogens.

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