GERMINATION RESPONSES OF NORTHERN RED MAPLE (ACER-RUBRUM) POPULATIONS

Samaras of red maple (Acer rubrum L.) were collected at six locations at the northern edge of its distribution. Two populations from souther n Quebec, in the deciduous forest, and four populations at its norther n limit in the boreal forest were selected. Germination responses of t hese populations were evaluated in growth chambers and in the field. T he effects of cold moist stratification, temperature (20/10 degrees C, 10/1 degrees C) and light intensity (750 mu mol . m(-2). s(-1), 160 m u mol . m(-2). s(-1)) were evaluated in growth chambers. Seeds collect ed at the two most southern sites had 46% to 90% germination without s tratification, while germination without stratification varied between 0% to 41% for the four most northern populations. In the six populati ons tested, the highest germination percentages were obtained at 10/1 degrees C under low light conditions. Cold moist stratification enhanc ed germination of the four most northern populations. We observed in t he field experiment that germination occurred during the summer months for sites located in the deciduous forest, while germination was dela yed until the next spring for the sites located in the boreal forest. The percentages of seedling emergence in the field were similar under shade and nonshade conditions. Overall, our results indicate a marked degree of dormancy in the most northern populations. The heterogeneous germination response of northern red maple populations could be assoc iated with the temperature regime at the collection site.