| Summary: | Visible frost damage to forest trees in Sweden seldom occurs in winter but is frequent in late spring, summer and early autumn. Frosts are frequent in all seasons in various parts of Sweden, even in the southernmost part (lat. 56°, N) and temperatures may be as low as -10°C even around mid-summer. Ice crystal formation within the tissues, which in most seedlings takes place at around -2°C, causes injury, not the sub-zero temperatures themselves. The apical meristem, the elongated zone, and the needles of seedlings of (L.) H. Karst. in a growing phase were damaged at about -3°C and those of L. at about -6°C. Other species of the genus were tested and most were found to be damaged at about -6°C, with some variations. species tested were damaged at about -3°C to -4°C.Picea abiesPinus sylvestrisPinusPiceaPinus contortaP. sylvestrisPicea abiesPicea mariana
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