Current issue: 55(4)
Under compilation: 55(5)
The objective of the study was to establish the influence of the founding density of a stand and the intensity of intermediate cutting on the quality of pine saw logs stems, primarily on their branchiness. Measurements were carried out in 68 Myrtillus-type and 32 Vaccinium-type Scots pine (Pinus sylvestris L.) stands. The quality of 1,982 sample trees was assessed.
According to the results, the branchless part of the stem is longest in the older age classes of trees. In all age classes the percentage of the branchless part is highest in medium sized stems. The relative height of the crown limit is greatest in small diameter classes and continues as the thickness of the tree increases. The crown is longer in the thicker tree. The grade of the butt log is on average highest in medium sized stems. Knottiness of a log made it unsuitable for a saw log only among the thickest stems. The relative share of the u/s grade decreased as the thickness of the trees increased.
From the point of view of early development of the trees it was concluded that in all age classes the branchless part is the shorter the faster the tree has grown in diameter when it was young. Also, branches of the butt log are the bigger the faster the tree has developed when it was young. The grade of the butt log improves as the thickness of the annual rings diminishes.
To produce good quality sawn timber, the pine stands should be established dense, and the first thinnings should be delayed as much as possible. The best time for the thinning would be when the diameter of the dominant trees at stump height is 12–15 cm and when all the branches have died on the length of the butt log. After the first thinning, comparatively intense intermediate thinning may be applied.
The PDF includes a summary in English.
Healthy, straight, more or less free from branches and slowly tapering stems are good raw material for woodworking industry. The aim of the study was to investigate, from the stand point of forest management, the influence of stand and forest site type on the technical quality of the stems. Sample plots were measured in Norway spruce (Picea abies (L.) H. Karst.) stands in Eastern Finland. Norway spruce growing in a stand with closed crowns developed thin branches and self-pruned, if the stand was dense in the early stages. The decisive time for the stand is, therefore, when it is at seedling stage and young stand. The stems are more branchy if the stand has been planted. The adequate planting density is discussed based on earlier studies. The sufficient density seems to be achieved when the spacing is at maximum two meters. When the stems are branchless up to four meters, thinning of spruce stand does not affect knottiness or stem form. A sparsely stocked, knotty young stand does not produce good-quality timber even if the stand is later dense. Selective thinning from above can be used to improve the quality of the wood.
The PDF includes a summary in German.
Cultivation of ash (Fraxinus exelsior L.), even though it is a native species in Finland, has been hindered by the belief that it cannot produce quality timber in Finland. However, it can be concluded that the quality of ash timber is as good as that of timber imported to the country, if the trees are grown in a fertile site, the crown density is high, and the stand is tended properly. In these conditions, ash wood may have 3 mm ring width or more. Measurements made in ash stands in Turku region and in Åland show that at the best sites ash trees reach a height of 20–22 m in 70–80 years. According to the field tests made by the author, it can be concluded that ash can be successfully grown in Southern Finland in Åland, Turku region, in the coastal areas of Uusimaa and in Karelian isthmus. The species requires a fertile, moist upland forest site. The early growth is best secured by planting the seedlings under a well thinned broadleaved stand, which is then thinned every fifth year. Open lands growing grass should be avoided.
The PDF includes a Finnish and German summary.