Full text of this article is only available in PDF format.

Steen Magnussen (email), René I. Alfaro, Paul Boudewyn

Survival-time analysis of white spruce during spruce budworm defoliation

Magnussen S., Alfaro R. I., Boudewyn P. (2005). Survival-time analysis of white spruce during spruce budworm defoliation. Silva Fennica vol. 39 no. 2 article id 382. https://doi.org/10.14214/sf.382

Abstract

Mortality and defoliation (DF%) in 987 white spruce (Picea glauca (Moench) Voss) trees were followed from 1992 to 2003 during an outbreak of the spruce budworm Choristoneura fumiferana (Clem.) in 15 white-spruce-dominated uneven-aged stands in the Fort Nelson Forest District near Prince George, British Columbia. Four stands were aerially sprayed with Bacillus thuringiensis (Bt). Defoliation and mortality levels were elevated in non-sprayed stands. The relationship between defoliation and survival-times was captured in a Cox proportional hazard model with a defoliation stress index (DSI), diameter (DBH), crown class (CCL), a random stand effect, Bt-treatment, and number of years of exposure to stand-level defoliation (DYEAR) as predictors. The DSI, optimized for discrimination between survivors and non-survivors, is the discounted sum of five lagged DF% values. Survival probabilities were predicted with a maximum error of 0.02. Hazard rates increased by 0.06 for every one point increase in DSI. CCL and random stand effects were highly significant. Bt-treatment effects were fully captured by DSI, CCL, and DYEAR.

Keywords
mortality; hazard rates; defoliation stress index; Cox proportional hazard regression; Choristoneura fumiferana

Author Info
  • Magnussen, Canadian Forest Service, Victoria, BC, Canada. V8Z 1M5 E-mail smagnussen@pfc.forestry.ca (email)
  • Alfaro, Canadian Forest Service, Victoria, BC, Canada. V8Z 1M5 E-mail ria@nn.ca
  • Boudewyn, Canadian Forest Service, Victoria, BC, Canada. V8Z 1M5 E-mail pb@nn.ca

Received 13 August 2004 Accepted 18 March 2005 Published 31 December 2005

Views 4472

Available at https://doi.org/10.14214/sf.382 | Download PDF

Creative Commons License CC BY-SA 4.0

Register
Click this link to register to Silva Fennica.
Log in
If you are a registered user, log in to save your selected articles for later access.
Contents alert
Sign up to receive alerts of new content

Your selected articles
Send to email
Parviainen J., (1985) Growth of young Scots pine, Norway spruce, siber.. Silva Fennica vol. 19 no. 4 article id 5249 (remove) | Edit comment
Huuri O., (1965) The effects of storage in cones on the viability.. Acta Forestalia Fennica vol. 78 no. 5 article id 7158 (remove) | Edit comment
Smolander H., (1984) Measurement of fluctuating irradiance in field s.. Acta Forestalia Fennica vol. 0 no. 187 article id 7634 (remove) | Edit comment
Ruel J. J., Ayres M. P. (1996) Variation in temperature responses among populat.. Silva Fennica vol. 30 no. 2–3 article id 5582 (remove) | Edit comment
Heliövaara K., Väisänen R. et al. (1991) Quantitative biogeography of the bark beetles (C.. Acta Forestalia Fennica vol. 0 no. 219 article id 7606 (remove) | Edit comment
Kangas A., Mehtätalo L. et al. (2007) Modelling percentile based basal area weighted d.. Silva Fennica vol. 41 no. 3 article id 282 (remove) | Edit comment
Calama R., Montero G. (2005) Multilevel linear mixed model for tree diameter .. Silva Fennica vol. 39 no. 1 article id 394 (remove) | Edit comment
Your search results