Growth and development of the introduced Picea L. (Karst.) species in the taiga zone (Karelia).
The study was conducted in the Botanical Garden of Petrozavodsk State University (South Karelia, the middle taiga subzone) from April to October during 1988-2016. The following representatives of the genus Picea were investigated: four introduced species (Picea glauca (Moench) Voss [syn. P. canadensis Britt.], P. pungens Engelm. f. viridis Regel., P. obovata Ledeb., and P. mariana Britt.) and one native species (P. abies (L.) Karst.). The growth of P. abies shoots starts 1-4 weeks earlier and ends 1-3 weeks later compared to the introduced species. The earliest culmination of shoot growth is observed in P. glauca and P. obovata and the latest in P. abies. The longest shoots are formed by P. abies. The growth dynamics of shoots differs considerably between the introduced species and the native species. The dates of the beginning and the culmination of the shoot growth in the studied species are to a certain extent affected by the temperature of the air. P. abies needles begin to grow 1-2 weeks earlier than the needles of the introduced species. The earliest culmination of needle growth is observed in P. obovata and P. glauca and the latest in P. pungens. P. abies and P. pungens show the largest needle length increment, while in the other species, it is 2-4 times smaller. The longest needles are formed in P. pungens and P. abies. There is a noticeable difference in needle growth dynamics between the introduced species and the native species. The dates on which needles begin to grow are largely determined by the temperature of the air. The temperature of the air and solar radiation produce a substantial effect on the time of occurrence of most phenophases in the studied Picea species. P. pungens and P. glauca were found to be the most promising spruce species for residential landscaping and creation of artificial plant communities in Karelia.