Frost hardiness in bark and needles of Norway spruce in southern Sweden

Bark necrosis and resin flows in Norway spruce have increased in southern S weden over the last few decades. Frost damage late in spring has been sugge sted as a possible cause, but other factors besides the climate may have co ntributed to the damage. The nutrient status influences the hardening proce sses and plants with poor nutritional conditions have an increased sensitiv ity to frost. In this study the sensitivity to frost of bark and the hardin ess status of needles of Norway spruce were compared with the nutrient stat us at two sites with different soil fertility. The trees were 30-40 years o ld. The hardiness status of the bark and needles was negatively affected by low concentrations of P and Mg.