Genetic variation among paper birch (Betula papyrifera MARSH.) populationsin germination, frost hardiness, gas exchange and growth

Patterns of genetic variation in paper birch (Betula papyrifera MARSH.) wer e evaluated at the population level. A sample of 18 populations from the so uth interior, central interior and north coast of British Columbia were exa mined in a number of traits related to germination (germination capacity, g ermination speed, peak value and germination value), fall and winter frost hardiness, gas exchange (transpiration rate, stomatal conductance, net phot osynthesis, instantaneous water use efficiency and mesophyll conductance) a nd biomass accumulation after the first and the second growing season. Anal ysis of variance or covariance revealed significant differences among the p opulations in all studied attributes except for stomatal conductance and he ight after the second growing season. Proportion of total variance attribut ed to population effect was up to 92% for germination parameters, 63% for f all frost hardiness, 22% for winter frost hardiness, 63% for biomass after the first growing season, 20% for biomass after the second growing season, and 5% for gas exchange variables. Germination speed and capacity were posi tively correlated and were higher in populations from colder climates. Cent ral interior populations had the highest level of fall frost hardiness and were the most uniform with respect to that trait. There were large variatio ns in fall frost hardiness within north coastal and south interior populati ons. Revealed patterns of variations have implications for paper birch gene tic resources management and conservation.