Current issue: 55(4)
Under compilation: 55(5)
Silver birch (Betula pendula Roth) is classified in diffuse-porous wood category. In this case structure of wood tissue is quite similar across whole cross-sectional area. The aim of this study was to analyse cross-section variability of moisture content (MC) of growing silver birch wood, significant hardwood species in Polish forests. Investigations were performed on 120 model trees. In the trunk of each model tree, an increment core was collected at breast height. Samples were collected of 30 different trees in four different seasons. The greatest MC was observed during winter, lowest MC in summer. Differences in MC were statistically significant only between winter versus spring, summer, and autumn. Distribution of MC on cross-section was similar in each season. The greatest average value was observed close to pith, then it was decreasing in bark direction. The greatest difference between observed in spring – 19.51% (p < 0.05) and lowest in autumn – 4.66%. Distribution of green density (GD) on cross section was inverse proportional to MC value. Variations in GD and MC are relevant for log transport planning, weight-scaling systems, lumber drying and dynamic assessment of stiffness. Therefore, from an environmental loss perspective, it is important to determine changes in MC and GD across the year.
The seasonal changes of the roots systems of a pine stand on the peatlands have been studied with samples collected during summers 1952-1954 and winter 1955. There are altogether seven sample areas that are located in the district of Korkeakoski.
The amount of roots is at the smallest in the spring, increasing then rapidly and peaking at the end of July. After that the amount of roots decreases again against the winter to the same size than in the spring. Variations seem to be similar in every year and also similar to other studies on mineral soils.
The PDF contains a summary in Finnish.
An investigation into the aerial distribution of Fomes annosus (now Heterbasidion annosum) in Finland was carried out. Prevalence of the fungus in the air was estimated from cultural counts of mycelia produced by diaspores which had fallen onto spruce discs and agar plates. The influence of climate on deposition of diaspores was determined from weather recordings.
For the main study, F. annosus diaspores collected from spruce stands in Helsinki, Anjala and Jokioinen were recorded at weekly or fortnightly intervals throughout 1968. Diaspores fell during the 24-hour periods almost continuously at all three observation sites from April to November, but the deposition was most frequent from late May to the end of October. The amounts of deposition varied greatly with the observation sites, seasons of the year, and time of the day. The fall was heaviest at Anjala and slightest at Jokioinen.
Throughout the season of deposition, more diaspores were trapped on all observation sites at night than during the day. A significant positive correlation was found between the fall of F. annosus diaspores and the air temperature. Diaspores of F. annosus were found in the forest on needles and leaves, and underneath the humus layer in mineral soil. The fall of diaspores decreased as the distance from sporophores increased.
The aerial distribution of two antagonists to F. annosus, viz. Peniophora gigantea and Trichoderma viride, was also studied. It was found that the diaspores of the former fell mainly during the same seasons as those of F. annosus.