Chronology of spruce budworm outbreaks near Lake Duparquet, Abitibi region, Quebec

Abstract

The chronology of eastern spruce budworm (Choristoneurafumiferana (Clem.)) outbreaks in the vicinity of Lake Duparquet in the Abitibi region, Quebec, was determined for a period of 200 years using dendroecological methods. Growth patterns of two budworm host species, balsam fir (Abiesbalsamea (L.) Mill.) and white spruce (Piceaglauca (Moench) Voss), were compared with white cedar (Thujaoccidentalis L.), a nonhost species, and with maps of defoliation surveys. The method permitted precise dating of past outbreaks prior to the last two decades, where cartographic information is either imprecise or nonexistent. Growth reductions associated with insect defoliation situate three outbreak periods in this century between 1970 and 1987, between 1930 and 1950, and between 1919 and 1929. A fourth outbreak period may have occurred in the 19th century between 1810 and 1832. The outbreaks in this region were less severe than those that have occurred further south of the insect's northern limit of dispersion. Nevertheless, they did have a major impact on the dynamics of balsam fir populations in the region, as revealed by a massive invasion of fir between 1915 and 1940, and a marked growth release between 1940 and 1950. Dry periods, reflected in the growth curve of cedar, were associated with recorded outbreak periods.

Can we reconstruct deer browsing history and how? Lessons from Gaultheria shallon Pursh

“…We suggest that the repetitive, irregular and partial defoliation by deer also explains the asynchronism observed in stem sections from deer-affected islands, in contrasts to the synchronism observed for sections collected on deer-free islands. Thus identifying, counting and dating abrupt growth changes in salal populations should allow to reconstruct the local history of deer browsing in a way similar to what has been done using adult tree rings [26] to reconstruct the history of insect outbreaks [31,32,42] or scars to reconstruct past caribou activity [33], porcupine expansion [36], beaver occupation [4] or changes in deer population [34,35].…”

“…Indeed, records of annual growth and wood density, age structure and morphological characteristics [13,25,27,43,56] are valuable signatures of past disturbances that have affected woody plants. Growth time series have been successfully used to infer spatial and temporal variations affecting several herbivore populations [31][32][33]36].…”

Predicting balsam fir growth reduction caused by spruce budworm using large-scale historical records of defoliation

“…B.S.P.). A recent historical study based on tree-ring analyses have shown that the frequency of spruce budworm outbreaks has remained quite stable over the last four centuries [9], presumably because of the continuous abundance of balsam fir stands [8,24,25]. Since fir-dominated stands are still abundant and are expected to remain so into the future, sustained management of these forests must consider the impact of future insect defoliation by integrating estimation of wood losses in volume prediction models.…”

Analyse dendroécologique de l'impact de la tordeuse des bourgeons de l'épinette (choristoneura fumiferana) suivant un gradient latitudinal en zone boréale au Québec : /

“…La standardisation permet la comparaison des arbres entre eux malgré leur différence de taille et de provenance (Swetnam et al 1985;Morin et al 1993). Elle permet aussi de diminuer les effets des facteurs autres que les épidémies qui peuvent influencer la croissance des arbres, comme l'âge de l'arbre et la situation géographique de chaque individu, en transformant les mesures de largeur de cernes en valeurs relatives (Fritts 1971(Fritts , 1976Swetnam et al 1985).…”