Dynamics of frost resistance in various provenances of Abies grandis Lindl.
The frost resistance of one year old needles and shoots of <em>Abies grandis</em> (seven provenances) and <em>Abies alba</em> (one provenance) was determined using Dexter's method since early autumn till late spring (September-May). Material was collected from trees over ten year old, planted in Beskid Sądecki Range near Krynica, 800 m above sea level. In this study it was found, that in early autumn (September) <em>A. grandis</em> develops weaker frost hardiness than <em>Abies alba</em>. In the late autumn and in winter, provenances coming from region II (according to Müller), and especially provenance 12016, are equal in respect to frost hardiness of shoots and needles to <em>Abies alba</em>. Among the provenances from Müller's region I exceptional frost hardiness is displayed by provenance 12005, which is also characterized by fast growth. In spring, <em>Abies alba</em> flushes earlier than <em>A. grandis</em>, which makes it more susceptible to late frosts.