Current issue: 54(4)
Under compilation: 54(5)
The mating system was analysed in the upper and lower crown of two groups of European larch (Larix decidua Mill.) clones divided according to the percentage of full seeds in the upper and lower crown parts. The overall multilocus estimate of outcrossing rate (t) was calculated to be 0.929. The differences of outcrossing rates between crown levels and clonal groups respectively were not statistically significant. The t estimates were greater for the upper crown level and for clones with higher percentage of full seeds in the upper crown level. However, among all observations there was no correlation between outcrossing rates and percentages of full seeds for particular crown levels and groups of clones. Observed similarity of outcrossing among grafts of the same clones may indicate genetic control of self-fertilization rate in individual European larch.
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The daily height growth rate of several larch species and progenies (Larix decidua, Larix sibirica, Larix laricina, Larix leptolepis) grown in a plastic greenhouse and in the open was measured. The growth pattern indoors was completely different compared with the normal outdoor growth pattern. The onset of growth took place in the greenhouse much earlier than outdoors and the phase of increasing growth was much shorter, as was expected. However, the phase of maximum growth was unexpectedly long. This fact suggests that there is great potential for using greenhouse cultivation to change the growth pattern of cultivated plants in order to obtain more complete utilization of the potential growing season.
The PDF includes a summary in Finnish.
About 100 years old larch (Larix sibirica Lebed. And L. decidua Mill.) trees were felled and the basic density samples taken from the stump level were determined. The number of trees was 21 and number of samples 378. The maximum basic density was reached at the age of 40–60 years, as counted from the pith. The basic density decreased as the width of the growth rings increased or the amount of heartwood decreased. The average basic density of the whole disc was 543 kg/m3 in L. sibirica and 497 kg/m3 in L. decidua. The basic densities of bark were 328 kg/m3 and 286 kg/m3, respectively.
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Foreign tree species have been planted in Finland since 1900s, the most famous being Larix sibirica plantations in Raivola in Karelia, which now belongs to Soviet Union. One of the largest larch plantations of Finland today is situated in Tuomarniemi, in Central Finland. Ten larch stands were established in Tuomarniemi between 1912 and 1937 mainly by planting. The stand established in 1937 was sown. The trees represent five larch species: Larix sibirica Ledeb. (5 stands), Larix gmelinii var. kurilensis (2 stands, current name probably Larix gmelinii var. gmelinii), Larix americana Michx. (1 stand, now Larix laricina), Larix decidua Mill. (1 stand) and Larix occidentalis Nutt. (1 stand). The total area of the larch stands is 82.5 ha. This paper reports the studies made in the plantations in 1958.
In Tuomarniemi larch grows well in many types of soil from Vaccinium type sites to fresh mineral soil sites. The age of the stands varies from 19 to 48, height from 12 to 24 metres and annual growth from 5 to 12 m3/ha. Larix sibirca has the best stem form of the species, followed by L. gmelinii var. kuriliensis. Easiest to split is the straight-grained L. gmelinii var. kuriliensis. L. sibirica is almost as easy to process. The wood of L. decidua, on the other hand, is often spiral-grained and tough. The trees are seldom infected with decay fungi.
The PDF includes a summary in German.
Broadcast sowing on snow was relatively new method in the beginning of the 20th century in Finland, and the experiences of regeneration were diverse. The aim of the survey was to study the success rate of regeneration in the oldest and largest areas regenerated with this sowing method in Tuomarniemi district. Scots pine (Pinus sylvestris L.) was the most common tree species, but also Norway spruce (Picea abies (L.) H. Karst.) and European larch (Larix decidua Mill.) were used in broadcast sowing on snow.
According to the study, the success of broadcast sowing on snow was as good as patch sowing and sowing in furrows in the sites typical for Tuomarniemi. The regeneration areas were often drained peatlands or paludified lands. When sowing is done using Norway spruce seeds, site preparation either by broadcast burning or scalping with hoe is recommended. Mixed sowing with pine and spruce seldom succeeded due to the differences in site requirements of the species and growth of seedlings. Sowing of Scots pine succeeded well on the drained peatlands. Sowing should be done some years after draining to let the peat dry and sink. Site preparation is needed in sites growing Polytrichum-moss. Broadcast burned areas larger than 10 hectares seemed to regenerate poorer than sites in average, possibly due to dryness of the sites. Trials with European larch were successful, and the growth of the seedlings acceptable despite the sites being relatively poor for the species.
The PDF includes a summary in German.