ESTABLISHING FELT-LEAF WILLOW FROM SEED TO RESTORE ALASKAN, USA, FLOODPLAINS

During 1991 and 1992 we conducted field experiments to determine the factors limiting the establishment and survival of felt-leaf willow (Salix alaxensis) seedlings on dry abandoned placer mine tailings along Birch Creek in interior Alaska. Study plots were used to test two variables, supplemental soil, and water. Willow establishment was highest on watered and topsoiled plots with very few seedlings established in unwatered plots. Seedling densities of up to 100 M-2 occurred for plots watered daily with 5 cm of topsoil. Seedling survival through 1992, however, was highest in plots that did not receive topsoil and lowest in plots with 5 cm topsoil. Seedling shoot and root weights were nearly 2 x and 3 x, respectively, greater on plots with no topsoil than plots with 5 cm topsoil. In addition, seedling shoot lengths were similar for both plot types, while root lengths were more than twice as long in the mineral soil plots as a 5 cm topsoil plot. Felt-leaf willow seedlings are readily established on placer tailings well above the water table by removing the limiting factor of summer drought. Addition of native organic-rich soils enhances establishment, but reduces survival. Willow seedling establishment is recommended for restoration sites where the water table is less than 1 to 2 m from the soil surface. We estimate that seedlings will root to the water table in approximately 5-yr.