Effect of seed source and nursery culture on paper birch (Betula papyrifera )uprooting resistance and field performance

Little is known about the effect of seed source and nursery culture on the growth and performance of artificially regenerated paper birch planted in the field. In the summer of 2000, trees were vertically uprooted in Prince George, BC using a tripod and winch device to determine if seed source and nursery culture significantly affected the root strength of 5-year-old paper birch. Trees from a seed source in the Skeena region had the greatest uprooting resistance, and the most root biomass, but the least root strength compared to the other three seed sources tested. The Skeena trees may be exhibiting an adaptive strategy which provides maximum root reinforcement across a wide range of environments. Uprooting resistance was similar for the 415D stocktypes grown at Red Rock and Kalamalka nurseries. However, trees grown in 515A styroblock at Kalamalka had the least uprooting resistance and root biomass of all treatments. In addition, the relationship between uprooting resistance and ground line diameter was different between nurseries. The results of this study suggest that regardless of height and diameter leaving the nursery, seed source root resistance and growth continued to be impacted by nursery culture 5 years after planting.