La dynamique récente des combes à neige du golfe de Richmond (Québec nordique): une analyse dendrochronologique

Abstract

Recent trends of variations in snowfall and in the duration of the clearing period of snow patches in Richmond Gulf (northern Quebec) have been studied using dendrochronological analysis of mechanical damage and the age structure of spruce populations. The mechanical damage (branch scars, bending of stems, and apical recovery) suffered by individuals of white spruce and black spruce found around the snow patches indicates the years or periods of overabundant snowfall during the 20th century (ca. 1919, 1930 to 1936, 1953 to 1955, 1958 and 1959, 1962 and 1963, 1968, 1972, 1976 and 1977, 1980 and 1981). Those years or periods also correspond to periods of good growth, as shown by trends of the standardized dendrochronological curve, plotted from data obtained from the oldest trees found nearby. Colonization of forest snow patches by white and black spruce since 1940 shows that overabundant snowfall does not prevent plant establishment. This spruce invasion is linked to early thawing resulting in a longer growth period. Also, a decrease in spruce establishment, an increase in the mortality rate of seedlings and coppice branches, as well as a reduction in the growth of trees after 1970 are linked to climatic cooling as evidenced by late thawing. [Translated by the Journal]