Dendrochronological investigation of Larixlyallii at Larch Valley, Alberta

Tree-ring chronologies have been developed for alpine larch (Larixlyallii Parl.), alpine fir (Abieslasiocarpa (Hook.) Nutt.), and Engelmann spruce (Piceaengelmannii Parry) for a tree-line site at Larch Valley in Banff National Park. The alpine larch and alpine fir chronologies are the first published chronologies developed for these species in the Canadian Cordillera. Alpine larch, a deciduous conifer, has many very narrow and missing rings, making chronology development difficult. These problems were resolved by identifying common marker rings among species growing at the same site. Chronologies for all three species show suppressed growth in the early to mid 1800s followed by a period of higher growth that peaked in the early to mid 20th century and has since declined. The exact timing and nature of response to favourable and unfavourable growth conditions vary with species. Alpine larch exhibits the highest sensitivity, lowest first-order autocorrelation, and greatest common variance, suggesting it has excellent potential as a source of proxy climate data for tree-line sites in this area. Preliminary correlations between Lake Louise climate data and larch ring-width and maximum latewood density chronologies show that there are significant correlations with summer temperature variables. Engelmann spruce and alpine fir growing at the same site show a similar response but are more strongly influenced by precipitation and growing conditions of the previous year.