Canadian Forest Service Publications

Condition du sapin et de l'épinette blanche dans la région du parc des Laurentides en 1979 face à l'épidémie de la tordeuse, et prévisions des pertes. 1980. Blais, J.R. Environnement Canada, Service canadien des forêts, Centre de recherches forestières des Laurentides, Sainte-Foy (Québec). Rapport d'information LAU-X-43. 16 p.

Year: 1980

Available from: Laurentian Forestry Centre

Catalog ID: 14342

Language: French

Series: Information Report (LFC - Québec)

CFS Availability: PDF (request by e-mail)


Thirty-seven study plots were established in 1979 throughout the Laurentian Park region to determine the impact of the current spruce budworm out break on balsam fir and white spruce of merchantable size. Of the 1,850 balsam fir examined, 12% were dead due to severe defoliation during the past four years. Mortality was more frequent among trees of smaller diameter (10 to 14 cm dbh); loss in merchantable volume amounted to 7% of total volume of balsam fir. Degree of defoliation was determined for each tree; 30% of the living balsam fir had lost more than 75% of their foliage. Most of these severely weakened trees will die during the next 2 or 3 years even without further defoliation.

For the past two years budworm populations regressed in the zone above 700 m (approximately 40% of the region), while maintaining at epidemic level at lower altitudes. Percentage of dead trees at higher altitudes was twice that at lower altitudes (17% and 8%). However, the percentage of very defoliated (moribond) trees was only 19% at higher, while it was 38% at lower altitudes. An egg-mass survey conducted in July 1979 indicated that populations will again be high at elevations below 700 m in 1980. This will undoubtedly result in very high losses during the coming two years; trees already dead plus the moribond trees amount to close to 50% of the balsam fir in this zone. The situation is aggravated since the most extensive stands of fir in the region are found in the zone below 700 m.

White spruce is a less common species in this region; of the 801 trees studied none were dead, and none had been subjected to a degree of defoliation that could result in death in the next two years. Should the out break persist, white spruce could be seriously affected in certain localities.

Pre-salvage and salvage operations should he conducted in fir stands in the Laurentian Park as soon as possible, otherwise losses amounting to millions of m3 can be expected.



Date modified: