SEED-GERMINATION, SEEDLING DEMOGRAPHY, AND GROWTH OF SALIX SETCHELLIANA ON GLACIAL RIVER GRAVEL BARS IN ALASKA

This study examines the recruitment from seed of Salix setchelliana Ba ll, a prostrate clonal willow, which grows in the gravel-bar habitat o f glacial rivers in Denali National Park, Alaska. Seeds of this specie s did not exhibit any dormancy. Under laboratory conditions, seeds moi stened immediately after collection showed 100% germination, and perce nt germination decreased with an increase in the length of dry storage . Since summer precipitation is generally frequent in this region, thi s is probably not a factor limiting recruitment. Most seedlings observ ed in the field were located on gravel bars with greater plant cover, as opposed to those with sparse plant cover. The survivorship of seedl ings over their first winter averaged 11%; in comparison, yearly survi vorship in years 1-6 averaged 69%. The most likely cause of mortality was insufficient carbohydrate accumulation. Seedling leaf area differe d between years and locations. An inverse relationship was found betwe en leaf area and age-class for seedlings of younger age-classes.