The aim of this study was to determine whether the growth rhythm and height growth differ between various larch provenances grown in greenhouse conditions. We also investigated whether the geographic and climatic conditions at the origin of the provenance could explain the possible differences between the provenances. The study material consisted of 16 Russian Siberian (Larix sibirica Ledeb.) and Dahurian larch (Larix gmelinii Rupr.) provenances and four seed sources from Finland as comparison lots. The growth rhythm differences were clearest between the southern and northern provenances; the southern provenances grew for a longer period and the proportion of late summer height growth was larger. Autumn colouration also developed later in these provenances. In the Russian larch material the provenances with a longer growing period had greater height growth. In the whole material the relationship was not so linear due to the deviating behaviour of the comparison material. Several of the Russian larch provenances were taller than the Finnish comparison seed lots, although the difference was not statistically significant. However, the growth of these provenances must be followed for a much longer period in field trials before any conclusions can be drawn about their usability in practical forestry.

The aim of this study was to analyse differences in the survival and height growth of, as well as damages to Siberian (Larix sibirica Ledeb.) and Dahurian (Larix gmelinii Rupr.) larch provenances over four growing seasons in field trials established in 2006 in southern (Punkaharju) and northern Finland (Kivalo). In this context, the study also investigated if the geographical and climatic conditions of the origin of the provenance could explain the differences between the provenances. The study material consisted of 20 Russian Siberian and Dahurian larch provenances and five seed sources from Finland (4) and Russia (1) as comparison lots. It was found that the Finnish seed sources of Siberian larch survived well in both the Kivalo and Punkaharju trials. Five northern latitude Russian provenances, of which one was Dahurian and the remainder were Siberian larches, had the highest survival in Kivalo. However, the differences observed in survival between provenances were only significant (p < 0.05) in Kivalo. Regardless of the trial, the differences, however, in height growth were significant and large between provenances. The southern Dahurian larches had a superior height growth in Punkaharju. The northern Dahurian larch provenance from Magadan (59°50´N, 150°40´E) had the largest height growth in Kivalo, among some northern Siberian larches. Damages were diverse, though Dahurian larches had less mammal damage than the Siberian larches. In general, the differences between provenances were not significant. Latitude and altitude best explained the differences between provenances, but also mean temperature, temperature sum and continentality index affected them (p < 0.05).

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The aim of this study was to analyse the growth rhythm, height growth and survival of seedlings of 20 Russian larch (Larix Mill.) provenances and five comparison entries in sowing year in greenhouse conditions and in field conditions in southern (Punkaharju 61°49′N, 29°19′E) and northern (Kivalo 66°19′N, 26°38′E) Finland after third and fourth growing seasons. Geographic and climatic conditions of the origins were used to explain the differences between the provenances. In the sowing year in greenhouse, latitude explained 74% of the length of the growing period. In the field in Punkaharju, the northern Siberian larches (Larix sibirica Ledeb.) had the earliest bud burst and the Dahurian larch (Larix gmelinii Rupr.) provenances slightly earlier onset of height growth. The temperature sum and latitude of the provenances explained the differences in shoot elongation. After four growing seasons in the field northern provenances had the best survival and height growth in Kivalo. Survival did not differ significantly between provenances in Punkaharju field experiment. The southern Dahurian larches had a superior height growth in Punkaharju and they had least mammal damages. In Punkaharju, the growth cessation was affected by photoperiod and possibly by declining temperatures in autumn. Provenances from cold northern climates developed their terminal buds first. They also formed autumn colouring and shed their needles earlier than more southern provenances. Dahurian larches showed potential in height growth and ability to utilize the length of the growing season effectively in Punkaharju. They also seemed to have, on average, smaller amount of mammal damages. Despite this, the currently used Siberian larch of Raivola origin is still the safest choice for larch forestry in whole Finland in terms of adaptation to climate. Further studies are needed still on the potential offered by different species and provenances (and their hybrids) to generalize the findings of this work.

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