A dendroecological analysis of eastern larch (Larixlaricina) in subarctic Quebec

Two new dendrochronological series of eastern larch (Larixlaricina (Du Roi) K. Koch) from subarctic Quebec extend from 1710 to 1987 (Whapmagoostui–Kuujjuarapik, eastern Hudson Bay) and from 1596 to 1978 (Rivière aux Feuilles, western Ungava). In both regions, the tree-ring series show similar long-term variations. Generally, conditions were more favorable for growth at the end of the 19th century and during the 20th century than before. A comparison of several larch and white spruce (Piceaglauca (Moench) Voss) tree-ring series from northern Quebec indicates significant shared variance between regions and species. Larch chronologies show two important depressions during the 20th century, between 1905–1908 and 1940–1946, which are more obvious in the two series from the southern forest–tundra than in the series from Ungava. These may be caused by outbreaks of the larch sawfly, Pristiphoraerichsonii (Htg.).