An examination of regional, provenance, and family variation in cold hardiness of Pinusmonticola

Seedlings from 29 seed lots of western white pine (Pinusmonticola Dougl. ex D. Don) from the British Columbia coast and interior ranges were tested for frost hardiness. Detached needles were exposed to a series of freezing temperatures, and relative hardiness was calculated based on visual scoring of injury. Seasonal progress in hardening was tested in seedlings maintained at the University of British Columbia (coastal) nursery. In addition, the same seed lots grown at a coastal and an interior field plantation were tested once during the hardening process. There was a significant (p = 0.04) regional difference between the coast and interior sources. The coastal region showed approximately 20% more damage than the interior region. Whereas provenances within a region did not differ in cold hardiness, families within a provenance did vary in this respect. The results suggest that the role of phenotypic plasticity in cold hardiness of P. monticola is reduced relative to other traits. It is recommended that s...