Conclusion
- Overall white spruce samples exhibited a very similar growth pattern which all tree ring widths sharply decreased in year 1999 and 2002; it's very likely caused by low precipitation in summer time (1999) and low temperature and drought(2002);
- However, populations from various origins showed significantly tree ring widths differences; individuals from local Alberta and Ontario have much higher growth performance comparing with others;
- White spruce samples from various provenances have population-specific interactions with climatic factors (precipitation and temperature), which can be applied to estimate the growth condition of certain white spruce population under certain climatic conditions;
- variances of drought tolerant indices among regions are mild.
- The limitation of this study: the sample size is not large enough to eliminate noise.