Histoire Recente des Epidemies de la Tordeuse des Bourgeons de l'Epinette au Nord du Lac Saint-Jean (Quebec): Une Analyse Dendrochronologique

1990

6 Abb., 35 Lit. Ang.

Unselbständiges Werk

9716

200088509

The chronology of spruce budworm (Choristoneura fumiferana (Clem.)) outbreaks for the past 200 years has been reconstructed by dendrochronological analysis of balsam fir (Abies balsamea (L.) Mill.) and white spruce (Picea glauca (Moench) Voss) samples from virgin forests, unaffected by insecticide spraying programs and recently protected against fires in the north and northwest of Lac Saint-Jean. Outbrekas began around 1974, 1944, 1909, and possibly, 1832. They are closely linked with those described in the Laurentide wildlife reserve. The frequency, duration and severity of growth rings suppression associated with outbreaks are similar to those registered during outbreaks in the southern forests, except for the 1974 outbreak, which was shorter and less severe. Other outbreaks registered in southern regions, where the proportion of balsam fir is higher, have reached this region where balsam fir populations are marginal. These results underline the importance of these ecological disturbances in the population dynamics of the host trees of the region.