This thesis presents the first climate reconstructions for the Canadian Cordillera using ring-width data from alpine larch ( Larix lyallii Parl.). This is also the first assessment of differences in tree-ring/climate relationships in this area that can be attributed to a climate data source. Nineteen sites and six regional chronologies were developed from living trees and subfossil wood. All chronologies had high mean sensitivity (0.22–0.33), low first order autocorrelation (0.22–0.59) and strong common variance (PC1 explains 48–67% of common variance). Mean chronology age is 650 years and the longest dates from 799–1993. Chronologies for sites along or west of the Continental Divide had strong, positive correlations with June temperatures from western stations, but the eastern chronologies had higher positive correlations with June–October averaged temperatures from prairie stations. Prairie winter precipitation had significant negative correlations with the southern and mid-network chronologies. The strongest tree-ring/climate relationships were not between the closest tree site/climate station pairs but between those separated by several hundred kilometers. Multiple regression was used to reconstruct summer temperatures (1597–1990) for Revelstoke, Castlegar, Cranbrook, southeastern B.C., Lake Louise, Calgary, Pincher Creek and Carway. Five significant principal components of 16 chronologies acted as predictors. The models explained 29–48% of the variance in the instrumental records. In most models, the early to mid 20th century was the warmest period in the past 400 years whereas the mid-1800s were the coldest years. The Carway reconstruction was different: the coldest period was the early 1600s and the 1790s were the warmest. Multiple regression also reconstructed June precipitation at Rogers Pass, B.C. and October to January precipitation at Claresholm, Alberta. The 1930s were the driest period in both models. At Rogers Pass, June precipitation was highest during the 1750s. Late fall and winter precipitation was highest during the 1790s at Claresholm.
展开▼
