|dc.description.abstract||Trees adapt to local climates, however growing concern surrounding climate
change has generated predictions suggesting mass extinction or redistribution of taxa
across the landscape. A lack of redistribution will result in species inhabiting suboptimal
conditions for growth and survival. Current reforestation efforts are to
understand how species will respond to different climates. Seed representing twenty-one
white birch (Betula papyrifera Marsh.) populations were collected, grown and planted in
a common garden study. Populations were observed for height, root collar diameter
(RCD) and survival percentage. There was a significant effect of population on each
growth variable. Survival had a positive correlation with height and RCD growth (May
to September) (Pearson’s r = 0.828 and 0.660 respectively). Summer temperature had a
strong relationship to each measured trait (r2 = 0.326 to 0.682 respectively).
The second set of observations was bud flush, bud cessation and leaf yellowing.
Bud flush observations began in early May and categorized bud development into six
stages from dormant to fully flush. Bud cessation commenced in the first week of
September every four days until bud set requirements were met. Leaf yellowing was
observed simultaneously with bud cessation until 50% leaf yellowing was achieved.
These traits represent phenological responses to temperature and photoperiod. There was
a significant effect of population on each variable. Bud flush had a strong negative
relationship with height growth, RCD growth and survival (r = -0.735, -0.693 and -0.539
respectively). Bud set influenced season length (Julian days), which had a positive
correlation to height growth, RCD growth and survival (r = 0.568, 0.407 and 0.537
respectively). Leaf yellowing also showed a positive correlation to height growth and
survival (r = 0.443 and .590 respectively).
Principal component analysis was utilized to summarize the 21 white birch
populations in regards to their growth and phenological responses to the common garden
study. Principal component analysis produced two components, which represented
24.2% and 16.61% of the variation respectively. No definitive titles were given to each
principal component. Temperature was a main predictor of growth and phonological
responses during the study. Summer and winter temperatures, along with growing
degree days (a function of temperature), were influential in predicting both growth and