The quality of 39 Japanese larch stands, mainly in north-western Poland, was characterized. On the basis of the presented results it can be concluded that properly managed forest stands of Japanese larch can compete in trees quality with stands of native larches. The alien species is more susceptible to a lower stand density and exposure to strong winds. This is no correlation between forest stand quality and growth dynamics.
Japanese larch (Larix kaempferi Sarg.) is one of the most frequent exotic species in Polish woodlands. The basic object of research comprised 60 stands of the studied species, located mainly in the northern and western parts of Poland. The growth results for the studied species, evaluated on the basis of the average height (hg55), were compared with data describing the local climate and the stand location within the botanical and climatic zoning. The results confirm the opinion that the Japanese larch prefers a climate of maritime character and generally shows high degree of flexibility regarding its climatic requirements (very large differences between the growth conditions in the studied area and the country of origin). The dependence between the growth results and precipitation is however lower than expected. The most interesting results include the relatively clear connection between the height of the larch stands and the Degórski’s (1984) ‘floristic’ ‘K’ (continentality) index.
It is commonly known that Japanese larch, Larix kaempferi was first introduced in Europe in Great Britain in 1861. In the presence of European larches, L. decidua it was not long before the first hybrids between these species, called Dunkeld larches (Larix × marschlinsii), emerged there. It was found that there were several hybrid larch trees in Estonia that sprouted before one of their parent species was introduced in Europe. One of the oldest Dunkeld larches growing in Tallinn is about 210 years old. The radial growth of three Dunkeld larches in Estonia (in the cities of Pärnu and Tallinn and in the manor park of Suure-Kambja) and the determination of their age by cumulative growth graphs are discussed, with consideration given to the available knowledge on the introduction of Japanese larch. The conclusion is that there may have existed earlier alternative introduction routes of Japanese larch into northern Europe via Russia.