Provenance variability in establishment of native downy birch in a 14-year trial in southwest Iceland

Abstract

Afforestation in southwest Iceland is hindered by eroded, infertile soils and salt deposition from strong oceanic winds. A trial plot of 25 provenances of native downy birch collected throughout Iceland was established in 1998 near Keflavik International Airport to identify the best adapted stock. Seedlings were fertilized in the early years; in 2003 lupine was transplanted into the plot. In 2012, the 25 provenances differed significantly in growth and survival. Both seedling height and survival correlated with latitude of provenance origin, but not with longitude, elevation, or distance from the Keflavik plot. Southern provenances performed better than other regions, with Thórsmörk best in both growth and survival. Local provenances were poorer in performance than many other southern provenances. For afforestation with downy birch, it is recommended that high-performing provenances be planted with initial artificial fertilization, accompanied by simultaneous seeding of lupine.